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Actuators
Volume 11
Issue 6
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Actuators, Volume 11, Issue 6 (June 2022) – 32 articles

Cover Story (view full-size image): This paper presents a novel cam-based variable stiffness actuator (VSA). It significantly differs from its counterparts in that the external load is distributed on its two motors with a small difference. It is a feasible method to improve VSA’s output power, especially in compact joints, such as rehabilitation devices. The stiffness adjustment involves a spring-balanced crank-slider mechanism with a variable-length base frame. Its tunable node is the common node for force decomposition, synthesis, stiffness adjustment, and position control by setting it as the common groove of two differential variable-pitch cams. The pitch curve synthesis method is put forward to optimize load distribution. The dual motors can work together closely in the same direction against the output load. View this paper
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14 pages, 926 KiB  
Article
Energy-Aware Model Predictive Control of Assembly Lines
by Francesco Liberati, Chiara Maria Francesca Cirino and Andrea Tortorelli
Actuators 2022, 11(6), 172; https://doi.org/10.3390/act11060172 - 20 Jun 2022
Cited by 1 | Viewed by 2429
Abstract
This paper presents a model predictive approach to the energy-aware control of tasks’ execution in an assembly line. The proposed algorithm takes into account both the need for optimizing the assembly line operations (in terms of the minimization of the total cycle time) [...] Read more.
This paper presents a model predictive approach to the energy-aware control of tasks’ execution in an assembly line. The proposed algorithm takes into account both the need for optimizing the assembly line operations (in terms of the minimization of the total cycle time) and that of optimizing the energy consumption deriving from the operations, by exploiting the flexibility added by the presence of a local source of renewable energy (a common scenario of industries that are often equipped, e.g., with photovoltaic plants) and, possibly, also exploiting an energy storage plant. The energy-related objectives we take into account refer to the minimization of the energy bill and the minimization of the peaks in the power injected and absorbed from the grid (which is desirable also from the perspective of the network operator). We propose a mixed-integer linear formulation of the optimization problem, through the use of H-infinite norms, instead of the quadratic ones. Simulation results show the effectiveness of the proposed algorithm in finding a trade-off that allows keeping at a minimum the cycle time, while saving on the energy bill and reducing peak powers. Full article
(This article belongs to the Special Issue Model Predictive Control in Mechatronic, Robotic, and Networked Systems)
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Figure 1
<p>Reference scenario.</p> Full article ">Figure 2
<p>Task dependency graph.</p> Full article ">Figure 3
<p>Energy tariff.</p> Full article ">Figure 4
<p>Photovoltaic power plant output.</p> Full article ">Figure 5
<p>Tasks Planning Simulation 1.</p> Full article ">Figure 6
<p>Power Grid Simulation 1.</p> Full article ">Figure 7
<p>Task Planning Simulation 2.</p> Full article ">Figure 8
<p>Power Grid Simulation 2.</p> Full article ">
16 pages, 4086 KiB  
Article
Electromechanical Performance of Biocompatible Piezoelectric Thin-Films
by S. Ranjan Mishra, Soran Hassani Fard, Taha Sheikh and Kamran Behdinan
Actuators 2022, 11(6), 171; https://doi.org/10.3390/act11060171 - 19 Jun 2022
Cited by 6 | Viewed by 3468
Abstract
The present study analyzed a computational model to evaluate the electromechanical properties of the AlN, BaTiO3, ZnO, PVDF, and KNN-NTK thin-films. With the rise in sustainable energy options for health monitoring devices and smart wearable sensors, developers need a scale to [...] Read more.
The present study analyzed a computational model to evaluate the electromechanical properties of the AlN, BaTiO3, ZnO, PVDF, and KNN-NTK thin-films. With the rise in sustainable energy options for health monitoring devices and smart wearable sensors, developers need a scale to compare the popular biocompatible piezoelectric materials. Cantilever-based energy harvesting technologies are seldom used in sophisticated and efficient biosensors. Such approaches only study transverse sensor loading and are confined to fewer excitation models than real-world applications. The present research analyses transverse vibratory and axial-loading responses to help design such sensors. A thin-film strip (50 × 20 × 0.1 mm) of each sample was examined under volumetric body load stimulation and time-based axial displacement in both the d31 and d33 piezoelectric energy generation modes. By collecting evidence from the literature of the material performance, properties, and performing a validated finite element study to evaluate these performances, the study compared them with lead-based non-biocompatible materials such as PZT and PMN-PT under comparable boundary conditions. Based on the present study, biocompatible materials are swiftly catching up to their predecessors. However, there is still a significant voltage and power output performance disparity that may be difficult to close based on the method of excitation (i.e., transverse, axial, or shear. According to this study, BaTiO3 and PVDF are recommended for cantilever-based energy harvester setups and axially-loaded configurations. Full article
(This article belongs to the Special Issue Multifunctional Active Materials and Structures Based Actuators)
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Figure 1

Figure 1
<p>The thin film piezoelectric model (dimensions and mesh).</p> Full article ">Figure 2
<p>The experimentally obtained voltage versus time for PVDF undergoing axial excitation.</p> Full article ">Figure 3
<p>The transverse vibration response of the thin-film energy harvesters: voltage output.</p> Full article ">Figure 4
<p>The transverse vibration response of thin film energy harvesters: power output.</p> Full article ">Figure 5
<p>The transverse vibration mechanical power input vs. electrical power output.</p> Full article ">Figure 5 Cont.
<p>The transverse vibration mechanical power input vs. electrical power output.</p> Full article ">Figure 6
<p>The axial-loading response of thin-film energy harvesters (<b>left</b>) and the mechanical power input vs. the electrical power output (<b>right</b>).</p> Full article ">Figure 6 Cont.
<p>The axial-loading response of thin-film energy harvesters (<b>left</b>) and the mechanical power input vs. the electrical power output (<b>right</b>).</p> Full article ">Figure A1
<p>The axial-loading: displacement functions.</p> Full article ">
16 pages, 5251 KiB  
Article
Design, Development and Experimental Assessment of a Cost-Effective Bellow Pneumatic Actuator
by Goran Gregov, Tomislav Ploh and Ervin Kamenar
Actuators 2022, 11(6), 170; https://doi.org/10.3390/act11060170 - 19 Jun 2022
Cited by 5 | Viewed by 2927
Abstract
Soft pneumatic actuators offer great advantages compared to rigid ones, particularly due to their compliant nature, which allows them to adapt to uncertainties in the environment. As such, they enable human-safe interactions and are often applied to various applications, such as for example, [...] Read more.
Soft pneumatic actuators offer great advantages compared to rigid ones, particularly due to their compliant nature, which allows them to adapt to uncertainties in the environment. As such, they enable human-safe interactions and are often applied to various applications, such as for example, soft grippers or wearable devices for human motion assistance. The presented research describes the process of design, development and finally control of two cost-effective bellow pneumatic actuators. The properties of the developed devices are experimentally assessed by performing three different types of experiments. In a first instance, the testing of blocking force was performed, followed by experimental assessment of velocity-displacement characteristics, and finally, the dynamical properties for sinusoidally forced motion were examined. It was shown that the actuator can provide over 100 N force and assure a contraction ratio over 40% of its full length, with maximum velocity exceeding 60 mm/s. Experimental responses to a sinusoidally forced motion allowed establishing that no significant change due to the fatigue, creep and relaxation occur in material properties. Finally, the positioning performances of both developed devices were assessed by employing PID and LQR controllers which allowed their precise position control with fast responses and steady-state errors within the 0.2 mm margin. The performed research gives some insights into the future development of the pneumatically driven mechatronics systems used for position control. Full article
(This article belongs to the Section Actuators for Robotics)
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Figure 1
<p>The process of development and experimental assessment of bellow PMAs: (<b>a</b>) 3D model of the design with its main elements; (<b>b</b>) used off-the-shelf bellow and parts developed by using additive manufacturing; (<b>c</b>) assembled devices; (<b>d</b>) device mounted and examined on the test-bench; and (<b>e</b>) experimental assessment of the operating parameters and position control.</p> Full article ">Figure 2
<p>(<b>a</b>) Assembled bellow PMAs; (<b>b</b>) experimentally obtained force vs. displacement curves.</p> Full article ">Figure 3
<p>Experimental setup.</p> Full article ">Figure 4
<p>Deforming of the structure of PMA2 for vacuum values higher than −0.55 bar.</p> Full article ">Figure 5
<p>Results of maximum blocking force: (<b>a</b>) PMA1; (<b>b</b>) PMA2.</p> Full article ">Figure 6
<p>Displacement over time for PMA1 (left column) and PMA2 (right column): (<b>a</b>) without external load; (<b>b</b>) 25 N load; (<b>c</b>) 70 N load.</p> Full article ">Figure 7
<p>Velocity vs. displacement curves for PMA1 (left column) and PMA2 (right column): (<b>a</b>) without external load; (<b>b</b>) 25 N load; (<b>c</b>) 70 N load.</p> Full article ">Figure 8
<p>Experimental results for 10-min long sinusoidally forced excitation: (<b>a</b>) PMA1; (<b>b</b>) PMA2.</p> Full article ">Figure 9
<p>Results of position control for PMA1 (left column) and PMA2 (right column) by employing PID (blue lines) and LQR controller (red lines): (<b>a</b>) 20 mm; (<b>b</b>) 40 mm reference.</p> Full article ">
16 pages, 3749 KiB  
Article
Multiphysical Simulation, Model Order Reduction (ECSW) and Experimental Validation of an Active Magnetic Bearing
by Johannes Maierhofer, Christoph Dietz, Oliver M. Zobel and Daniel J. Rixen
Actuators 2022, 11(6), 169; https://doi.org/10.3390/act11060169 - 17 Jun 2022
Cited by 3 | Viewed by 2075
Abstract
Model order reduction techniques can be used during the operation phase of a product to generate virtual sensor outputs and enable diagnosis and monitoring systems. This contribution shows an approach with the example of an active magnetic bearing. The reduced model is used [...] Read more.
Model order reduction techniques can be used during the operation phase of a product to generate virtual sensor outputs and enable diagnosis and monitoring systems. This contribution shows an approach with the example of an active magnetic bearing. The reduced model is used to calculate a non-measurable physical quantity (here force) and uses a measurable quantity (temperature) to check for plausibility. As a test case, the dynamic force response under the influence of varying eddy currents due to temperature changes is investigated. Using a special test rig with a 6-dof force measurement platform, the effects are shown and the simulation results are validated. Full article
(This article belongs to the Special Issue Selected Papers from the 17th International Symposium on Magnetic Bearings (ISMB17))
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Figure 1
<p>Schematic flywheel energy storage system (FESS) wherein red—stator; green—rotor with inertia; and blue—active magnetic bearing.</p> Full article ">Figure 2
<p>Monitoring scheme for the AMB. The simulation is fed with the measured currents and simulates the magnetic bearing. A comparison of the measured temperature with the simulated temperature gives a hint whether the simulation matches reality and can therefore be trusted.</p> Full article ">Figure 3
<p>Generic material laws for the rotor and stator in comparison to data from the datasheets.</p> Full article ">Figure 4
<p>Nonlinear material law for the electrical conductivity of iron with <math display="inline"><semantics> <mrow> <msub> <mi>σ</mi> <mn>0</mn> </msub> <mo>=</mo> <mn>10</mn> </mrow> </semantics></math>MS/m and <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mrow> <mn>0.0058</mn> </mrow> <mrow> <mn>1</mn> <mo>/</mo> </mrow> </mrow> </semantics></math>K in comparison to [<a href="#B10-actuators-11-00169" class="html-bibr">10</a>].</p> Full article ">Figure 5
<p>Timeintegration strategy with <math display="inline"><semantics> <msub> <mi>t</mi> <mi>i</mi> </msub> </semantics></math> being the magnetodynamic period and <math display="inline"><semantics> <msub> <mi>T</mi> <mi>j</mi> </msub> </semantics></math> denoting the large timestep used for the time integration of the thermodynamic model.</p> Full article ">Figure 6
<p>Two-dimensional model of an active magnetic bearing with finite element mesh.</p> Full article ">Figure 7
<p>Magnetic energy and co-energy for a nonlinear material.</p> Full article ">Figure 8
<p>Exemplary ECSW elements and corresponding weights of the reduced mesh.</p> Full article ">Figure 9
<p>Active magnetic bearing and the experimental setup with a 6-dof force measurement platform and temperature sensors to calibrate the simulation in relation to measured forces and temperatures.</p> Full article ">Figure 10
<p>Calibration of heat transfer coefficients using the measured temperature decays.</p> Full article ">Figure 11
<p>Resulting static magneto-static force obtained by simulation with an effective thickness of the bearing to compensate for leakage and fringing effects (comparison to measured forces).</p> Full article ">Figure 12
<p>Temperature development in the magnetic bearing for an excitation of 400 Hz and <math display="inline"><semantics> <mrow> <msub> <mi>I</mi> <mi>c</mi> </msub> <mo>=</mo> <mn>5</mn> <mrow/> </mrow> </semantics></math> A.</p> Full article ">Figure 13
<p>Measured force values at <math display="inline"><semantics> <mrow> <mi>f</mi> <mo>=</mo> <mn>400</mn> <mrow/> </mrow> </semantics></math> Hz plotted over one period at different time points and temperatures.</p> Full article ">Figure 14
<p>Increase of measured and simulated peak force values over different combinations of temperatures in rotor and stator. The simulation can show the qualitative effect compared to the measured values but less pronounced.</p> Full article ">
56 pages, 5179 KiB  
Review
Biorobotics: An Overview of Recent Innovations in Artificial Muscles
by Matthew Craddock, Emmanuel Augustine, Sam Konerman and Minchul Shin
Actuators 2022, 11(6), 168; https://doi.org/10.3390/act11060168 - 17 Jun 2022
Cited by 13 | Viewed by 7578
Abstract
In this overview of recent developments in the field of biorobotics we cover the developments in materials such as the use of polyester fabric being used as artificial skin and the start of whole new ways to actuate artificial muscles as a whole. [...] Read more.
In this overview of recent developments in the field of biorobotics we cover the developments in materials such as the use of polyester fabric being used as artificial skin and the start of whole new ways to actuate artificial muscles as a whole. In this, we discuss all of the relevant innovations from the fields of nano and microtechnology, as well as in the field of soft robotics to summarize what has been over the last 4 years and what could be improved for artificial muscles in the future. The goal of this paper will be to gain a better understanding of where the current field of biorobotics is at and what its current trends in manufacturing and its techniques are within the last several years. Full article
(This article belongs to the Special Issue Artificial Muscles for Biorobotics: Study, Application and Future Perspectives)
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Figure 1
<p>The counterclockwise ACW and clockwise CW square twist are actuated by a vacuum. The section is an overhead view of what direction the vacuum is actuating on the example piece, whereas the orange section is an isometric view of what happened on the example piece as a result of the vacuum’s actuation (Reprinted with permission from Jiao et al. [<a href="#B12-actuators-11-00168" class="html-bibr">12</a>]. Copyright 2021, CC BY NC ND 4.0 International).</p> Full article ">Figure 2
<p>(<b>a</b>) is an example of the sensor placement along the soft cylindrical body, these sensors are placed at even intervals to align with the <span class="html-italic">x</span> and <span class="html-italic">y</span> axes. The locations of the sensors would be on the opposite side of other sensors in this example, which would have them all around the cylinder. (<b>b</b>) is a schematic of a constant curvature beam on the cylindrical body itself (Reprinted with permission from Liu, M. et al. [<a href="#B25-actuators-11-00168" class="html-bibr">25</a>]. Copyright 2021, CC BY 4.0 International).</p> Full article ">Figure 3
<p>(<b>a</b>) represents a render of the CPLA component undergoing thermal application measuring its specific levels of thermal energy at different points along it. Where there is a higher thermal measurement at a specific point along the CPLA is represented by the lighter color with red being the hottest, at the point seen it has created a bend in this CPLA material. (<b>b</b>) is what the material actually looks like now as a result of the thermal application due to the concentration of Joule heating (Reprinted with permission from Bai, L. et al. [<a href="#B32-actuators-11-00168" class="html-bibr">32</a>]. Copyright 2021, CC BY 4.0 International).</p> Full article ">Figure 4
<p>(<b>a</b>) shows the composition of the hand assembly, which is comprised of a soft layer for the index, thumb, and middle finger. (<b>b</b>) shows the way that the interconnected joints of the finger assembly connect to one another with dovetail anchor plugs and sockets (Reprinted with permission from Zhu, G. et al. [<a href="#B36-actuators-11-00168" class="html-bibr">36</a>]. Copyright 2020, CC BY 4.0 International).</p> Full article ">Figure 5
<p>(<b>a</b>) shows the dimensions as well as a breakdown of this soft layer’s composition. It is comprised of a basic layer, then a spacing layer, followed by the suction layer, and ends with a soft top layer. (<b>b</b>) shows the inflation module in greater detail and with its dimensions, it has a simpler composition of a base and then layers. (<b>c</b>) shows the structure in real time, breaking down where what the suction and inflation modules look like, as well as pointing out the air tubes to allow for the inflation modules’ actuation (Reprinted with permission from Zhu, G. et al. [<a href="#B36-actuators-11-00168" class="html-bibr">36</a>]. Copyright 2020, CC BY 4.0 International).</p> Full article ">Figure 6
<p>This shows the teleoperated bimanual assembly carrying a large assortment of different shapes and sizes to show how well it can grip with its soft layer and cumulative hand strength (Reprinted with permission from Zhu, G. et al. [<a href="#B36-actuators-11-00168" class="html-bibr">36</a>]. Copyright 2020, CC BY 4.0 International).</p> Full article ">Figure 7
<p>Fabrication and characterization of graphene fiber artificial muscles, (<b>a</b>) is the scheme of the graphene fiber fabrication; the arrow indicates the direction of rotation; (<b>b</b>) SEM images of the directly dried graphene fiber, and (<b>c</b>) twisted graphene fiber (Reprinted with permission from Foroughi, J. et al. [<a href="#B55-actuators-11-00168" class="html-bibr">55</a>]. Copyright 2020, CC BY 4.0 International).</p> Full article ">Figure 8
<p>The image on the <b>left</b> is a three-dimensional model of a single-walled carbon nanotube (SWCNT). The image on the <b>right</b> is three SWCNTs concentrically aligned on top of one another, also known as a multi-walled carbon nanotube (MWCNT) (Reprinted with permission from Ganesh, E.N. [<a href="#B64-actuators-11-00168" class="html-bibr">64</a>]. Copyright 2013, CC BY NC ND 4.0 International).</p> Full article ">Figure 9
<p>Fullerene C<sub>60</sub> (Reprinted with permission from Mohan, V.B. et al. [<a href="#B50-actuators-11-00168" class="html-bibr">50</a>]. Copyright 2018, with permission from Elsevier).</p> Full article ">Figure 10
<p>This is a simplified diagram with brief explanations of each of the molecular robot’s components and how each “robot” interacts with one another (Reprinted with permission from Matsuda, K. et al. [<a href="#B85-actuators-11-00168" class="html-bibr">85</a>]. Copyright 2019 American Chemical Society).</p> Full article ">Figure 11
<p>Simple McKibben PAM actuation sequence. (<b>a</b>) has the inner sleeve shown at rest with the sleeve and rubber tube holding an inner air tube to feed the air supply into. (<b>b</b>) shows the sleeve becoming pressurized and showing an expansion of the air and rubber tube as well as the sleeve expanding in the radial direction (Reprinted with permission from Peng, Y. et al. [<a href="#B106-actuators-11-00168" class="html-bibr">106</a>]. Copyright 2019, with permission from Elsevier).</p> Full article ">Figure 12
<p>Origami-inspired vacuum actuator. Found in source [<a href="#B13-actuators-11-00168" class="html-bibr">13</a>]. (<b>a</b>,<b>b</b>) illustrate the origami inspiration for the vacuum actuators. (<b>c</b>,<b>d</b>) show the dimensions of the actuator. (<b>e</b>) shows the special change in design for the bending actuator. (<b>f</b>) illustrates the focal point of the buckling action, the blue arrows point toward the direction of the movement towards the focal point. (<b>g</b>,<b>h</b>) show the working action of the twisting-contracting and twisting-bending actuators, respectively (Reprinted with permission from Jiao, Z., et al. [<a href="#B13-actuators-11-00168" class="html-bibr">13</a>]. Copyright 2019, CC BY 4.0 International).</p> Full article ">Figure 13
<p>Novel winding artificial muscle driven by pneumatic silicone tubes, (<b>a</b>) shows the tubes at rest in a layout comprised of multiple silicone tubes with the wires sat within the grooves of the tubes. (<b>b</b>) shows the pressurized pneumatic assembly actuating causing the tubes to contract closer to one another (Reprinted with permission from Xie, D. et al. [<a href="#B126-actuators-11-00168" class="html-bibr">126</a>]). 2021, CC BY 4.0 International.)</p> Full article ">Figure 14
<p>PAMs with different pressures, where <math display="inline"><semantics> <mrow> <msub> <mi>L</mi> <mn>0</mn> </msub> </mrow> </semantics></math> is the muscle length without being pressurized, <math display="inline"><semantics> <mrow> <msub> <mi>L</mi> <mi>n</mi> </msub> </mrow> </semantics></math> is the muscle length under pressure, and <math display="inline"><semantics> <mrow> <mo>△</mo> <mi>L</mi> </mrow> </semantics></math> is the increase in length (Reprinted with permission from Al-Fahaam, H. et al. [<a href="#B112-actuators-11-00168" class="html-bibr">112</a>]. Copyright (2018), with permission from Elsevier).</p> Full article ">Figure 15
<p>EBPAM pressurized under different amounts of pressure; increasing from top-left to bottom-right (Reprinted with permission from Al-Fahaam, H., et al. [<a href="#B112-actuators-11-00168" class="html-bibr">112</a>]. Copyright (2018), with permission from Elsevier).</p> Full article ">Figure 16
<p>A simple TFAM experiencing thermal actuation (Reprinted with permission from Leng, X., et al. [<a href="#B26-actuators-11-00168" class="html-bibr">26</a>] Copyright 2020, CC BY NC ND 4.0 International).</p> Full article ">Figure 17
<p>Three LCEs actuated by electrothermal film in series, these are controlled electronically by running more thermal energy within each of the three sections, (<b>ii</b>) shows the bottom section 3 deforming from being exposed to the electronic external stimuli. (<b>iii</b>) shows another example of actuation after previously deforming the previous section 3 within (<b>ii</b>), in (<b>iii</b>) section portions 3 and 2 have become bent due to the electronic external stimuli. (<b>iv</b>) shows the last example of all three 3, 2, and 1 becoming subjected to the electronic external stimuli and having them all deform as a result (Reprinted with permission from Liu, H., et al. [<a href="#B139-actuators-11-00168" class="html-bibr">139</a>]. Copyright 2020, American Chemical Society).</p> Full article ">Figure 18
<p>Diagram of pneumatic artificial muscle with components labeled, D is the width of the overall sleeve assembly, L is the overall length of the assembly, θ is the braided angle (Reprinted with permission from Al-Ibadi, A., et al. [<a href="#B145-actuators-11-00168" class="html-bibr">145</a>]. Copyright 2018, CC BY 4.0 International).</p> Full article ">Figure 19
<p>(<b>a</b>) diagram of the fabrication process of a TCA separated into 4 steps: twist insertion, clamping, annealing, and stretching. (<b>b</b>) Images from an optical microscope of the TCA initial and stretched state (Reprinted with permission from Hwang, I., et al. [<a href="#B147-actuators-11-00168" class="html-bibr">147</a>]. Copyright 2022, CC BY 4.0 International).</p> Full article ">Figure 20
<p>Diagram outline the programming and transition phases of a two-way shape memory polymer (Reprinted with permission from Scalet, G. [<a href="#B151-actuators-11-00168" class="html-bibr">151</a>]. Copyright 2020, CC BY 4.0 International).</p> Full article ">Figure 21
<p>Schematic diagram of crystal structure evolution of NiTi SMA tube subjected to stress-induced martensite (SIM) transformation (Reprinted with permission from Jiang, S., et al. [<a href="#B154-actuators-11-00168" class="html-bibr">154</a>]. Copyright 2017, CC BY 4.0 International).</p> Full article ">Figure 22
<p>Brushing method for the stretchable electrode and the fabrication method for a single-layer DEA, (<b>a</b>) shows the first step of laying down the 10 mm square piece of masking sheet that has a hole in the middle of it which is the exposed desired part of the elastomer membrane that will be worked on. (<b>b</b>) shows the pouring of the CNT powder, and (<b>c</b>) shows the use of a brush to prep for spreading the CNT powder across the hole onto the bare elastomer membrane within the hole of the masking sheet. (<b>d</b>) shows the further spreading of the CNT powder across the exposed portion of the elastomer membrane within the masking sheet enough to create a thin layer of CNT across the whole exposed area. (<b>e</b>,<b>f</b>) shows them then pulling off the masking sheet to show the now created concentrated CNT powdered portion now considered an electrode. (<b>g</b>) shows the now formed electrode as result of this concentrated CNT powder on this specific portion of the elastomer membrane (Reprinted with permission from Wiranata, A., et al. [<a href="#B157-actuators-11-00168" class="html-bibr">157</a>]. Copyright 2021, CC BY NC ND 4.0 International).</p> Full article ">Figure 23
<p>All scale bars are 5 mm long. (<b>a</b>) Two masks (gray) were used, one for each rubbing direction indicated by blue arrows and gray lines. (<b>b</b>) In the rubbing overwriting method, the entire surface is rubbed in one direction first and one mask is used for the regions with a perpendicular rubbing direction. (<b>c</b>,<b>d</b>) LCE films prepared with the rubbing overwriting technique using: (<b>c</b>) a mask with the University of Warsaw logo cut out and (<b>d</b>) a mask with 1 mm wide slits cut out. The yellow box shows how the accordion-like actuator was cut from the film. White light photographs were taken between crossed polarizers, with the white cross showing the orientation of the polarizers. (<b>e</b>) Accordion-like deformation in a stripe of LCE film cut perpendicular to the pattern lines, heated from 30 °C to 90 °C. (<b>f</b>) Finite element simulation of the LCE stripe deformation. Temperature values relate to conditions in (<b>e</b>,<b>f</b>) (Reprinted with permission from Rogóż, M., et al. [<a href="#B159-actuators-11-00168" class="html-bibr">159</a>]. Copyright 2021, CC BY 4.0 International).</p> Full article ">Figure 24
<p>Diagram of the fabrication of molecular motors (Reprinted with permission from Thai, M.T. et al. [<a href="#B88-actuators-11-00168" class="html-bibr">88</a>]. Copyright 2019 American Chemical Society).</p> Full article ">
14 pages, 5924 KiB  
Article
A Design of Biomimetic Prosthetic Hand
by Sakura Narumi, Xiansong Huang, Jongho Lee, Hiroyuki Kambara, Yousun Kang and Duk Shin
Actuators 2022, 11(6), 167; https://doi.org/10.3390/act11060167 - 16 Jun 2022
Cited by 9 | Viewed by 5154
Abstract
Many patients with upper limb defects desire myoelectric prosthetic hands, but they are still not used for some reasons. One of the most significant reasons is its external appearance, which has the discomfort caused by the structural difference between a human hand and [...] Read more.
Many patients with upper limb defects desire myoelectric prosthetic hands, but they are still not used for some reasons. One of the most significant reasons is its external appearance, which has the discomfort caused by the structural difference between a human hand and a robotic link. The structure must be based on human anatomy to create a more natural-looking prosthesis. This study designed a biomimetic prosthetic hand with bones, ligaments, tendons, and multiple muscles based on the human musculoskeletal system. We verified the proposed prosthetic hand using the viscoelastic angle sensor to determine whether it works like a human hand. We also compared the finger force of the prosthetic hand with that of a human finger. It could be capable of controlling the angle and the stiffness of the joint by multiple extensor and flexor muscles, like humans. Full article
(This article belongs to the Special Issue Intelligent Robotic and Prosthetic Hands: Design, Control and Application)
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Figure 1
<p>Hand anatomy: (<b>a</b>) joint and phalanges of the hand; (<b>b</b>) adjusted 3D bone model (thumb and index) using Japanese standard female data.</p> Full article ">Figure 2
<p>Finger joints schematic diagram: (<b>a</b>) hinge joint; (<b>b</b>) saddle joint; (<b>c</b>) metacarpal of thumb model with a ball and socket joint part (left: front view, right: oblique downward view).</p> Full article ">Figure 3
<p>Design of ligaments (<b>left</b>: collateral ligament, <b>right</b>: palmar ligament).</p> Full article ">Figure 4
<p>Design of tendons and tunneled tube in bone: (<b>a</b>) 3D model; (<b>b</b>) 3D printed bone.</p> Full article ">Figure 5
<p>Trajectory of tendon sheath designed on the phalange model: (<b>a</b>) For the index, (1), (2) extensor digitorum, (3) flexor digitorum profundus, and (4) interosseous and lumbricals are designed. For the thumb, (5) flexor pollicis longus, (6) adductor pollicis, (7) extensor pollicis longus, and (8) abductor pollicis longus; (<b>b</b>) Prototype of the biomimetic fingers.</p> Full article ">Figure 6
<p>The proposed system for prosthetic hand.</p> Full article ">Figure 7
<p>The custom-made angle sensDor: (<b>a</b>) prototype sensor; (<b>b</b>) gesture recognition of unity.</p> Full article ">Figure 8
<p>Index finger operation with multiple muscles. (<b>a</b>) neutral position; (<b>b</b>) flexion of index (<a href="#app1-actuators-11-00167" class="html-app">Video S1</a>); (<b>c</b>) IP and DIP joints operation (<a href="#app1-actuators-11-00167" class="html-app">Video S2</a>); (<b>d</b>) MP joint only operation (<a href="#app1-actuators-11-00167" class="html-app">Video S3</a>).</p> Full article ">Figure 9
<p>Angle of each joint from liquid metal sensor. Upper panel from human movements. Bottom panel from finger robot. Blue lines show MP joint movements. Red lines represent those of IP joint. Orange lines stand for those of DIP joint. (<b>a</b>) Flexion and extension operation; (<b>b</b>) IP/DIP joint operation; (<b>c</b>) MP joint only operation.</p> Full article ">Figure 10
<p>Thumb operation with multiple muscles. (<b>a</b>) Abduction position of CM; (<b>b</b>) IP/MP flexion with CM abduction (<a href="#app1-actuators-11-00167" class="html-app">Video S6</a>); (<b>c</b>) Adduction position of CM; (<b>d</b>) IP/MP flexion with CM adduction (<a href="#app1-actuators-11-00167" class="html-app">Video S7</a>).</p> Full article ">Figure 11
<p>The index force of human and the prosthetic hand.</p> Full article ">Figure 12
<p>Schematic of the 20-channel control board with serial communication between HOST PC and the board and between the main board and slave board at the controller board.</p> Full article ">
14 pages, 4475 KiB  
Article
Development of a Series Elastic Tendon Actuator (SETA) Based on Gait Analysis for a Knee Assistive Exosuit
by Hee Don Lee, Heejin Park, Dae Han Hong and Tae Hun Kang
Actuators 2022, 11(6), 166; https://doi.org/10.3390/act11060166 - 15 Jun 2022
Cited by 6 | Viewed by 3056
Abstract
An exosuit is a wearable robot that assists the muscular strength of a human that wears it by using multiple wires with similar functions to human muscles. This study focuses on the development of a series elastic tendon actuator (SETA) for the actuation [...] Read more.
An exosuit is a wearable robot that assists the muscular strength of a human that wears it by using multiple wires with similar functions to human muscles. This study focuses on the development of a series elastic tendon actuator (SETA) for the actuation of an exosuit. A gait analysis was performed for walking on stairs to deduce the design requirements of SETA, and the necessary performances were then determined based on these requirements. The SETA is designed to assign compliance to rigid wires using linear springs. The deformation in linear springs generated during tension was measured through an encoder to calculate the human robot interaction (HRI) force. By utilizing the HRI force as feedback of an admittance controller, the SETA was capable of providing wire tensions required by an exosuit. The performance of the SETA was verified through series elastic component (SEC) deformation and force control experiments. The SEC deformation increased from 0 to 3.86 mm when the wire tension increased from 0 to 100 N. This force controller demonstrated a slight vibration owing to the mechanical properties of the springs constituting the SEC during the step input; however, the value gradually converged to 100 N. The developed SETA was applied to an exosuit system for supporting knee strength of the elderly when walking on stairs. Full article
(This article belongs to the Special Issue Actuation Solutions for Wearable Robots)
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<p>Knee assistive exosuit using new type of series elastic tendon actuator (SETA).</p> Full article ">Figure 2
<p>Construction of experimental setup for gait analysis during stair ascent and descent.</p> Full article ">Figure 3
<p>Gait analysis results (mean and standard deviation) of knee joint during stair ascent and descent: (<b>a</b>) knee joint angle; (<b>b</b>) knee joint power; and (<b>c</b>) knee joint moment.</p> Full article ">Figure 4
<p>Design concept of series elastic tendon actuator (SETA).</p> Full article ">Figure 5
<p>System sizing results of series elastic tendon actuator (SETA).</p> Full article ">Figure 6
<p>Mechanism design of series elastic tendon actuator (SETA) module for human power assistance of both knee joints: (<b>a</b>) SETA module mechanism; (<b>b</b>) Series elastic component (SEC) mechanism; and (<b>c</b>) SETA module for exosuit.</p> Full article ">Figure 7
<p>Block diagram of admittance controller for force control in series elastic tendon actuator (SETA).</p> Full article ">Figure 8
<p>Experimental setup for performance evaluation of series elastic tendon actuator (SETA).</p> Full article ">Figure 9
<p>Experimental results of series elastic component (SEC) deformation: (<b>a</b>) SEC deformation with wire tension; and (<b>b</b>) Mean and standard deviation (SD) of deformation error.</p> Full article ">Figure 10
<p>Experimental results of force control when ramp signal is input: (<b>a</b>) control response; and (<b>b</b>) mean and standard deviation (SD) of control error.</p> Full article ">Figure 11
<p>Experimental results of force control when step signal is input: (<b>a</b>) control response; and (<b>b</b>) mean and standard deviation (SD) of control error.</p> Full article ">
17 pages, 4944 KiB  
Article
Performance Analysis of Magnetorheological Damper with Folded Resistance Gaps and Bending Magnetic Circuit
by Leping Liu, Yinan Xu, Feng Zhou, Guoliang Hu and Lifan Yu
Actuators 2022, 11(6), 165; https://doi.org/10.3390/act11060165 - 15 Jun 2022
Cited by 8 | Viewed by 2393
Abstract
The traditional magnetorheological (MR) damper subject to the limited space has shortcomings such as small damping force, narrow dynamic range and low adaptability. In this study, a new MR damper with folded resistance gaps and bending magnetic circuit was proposed for improving the [...] Read more.
The traditional magnetorheological (MR) damper subject to the limited space has shortcomings such as small damping force, narrow dynamic range and low adaptability. In this study, a new MR damper with folded resistance gaps and bending magnetic circuit was proposed for improving the damping performance. The length of the resistance gap was increased by configuring the multi-stage folded annular gap structure, and the magnetic circuit was established to activate the non-flux region. The mathematical model was established for the MR damper to analyze the damper force, magnetic circuit and dynamic performance. Subsequently, the finite element analysis (FEA) methodology was utilized to investigate the changes of magnetic flux densities in the folded resistance gaps. The test rig was setup to explore and verify the dynamic performance of the proposed MR damper under different excitation conditions. The results indicate the maximum damping force is approximately 4346 N at the current of 1.5 A, frequency of 0.25 Hz and amplitude of 7.5 mm. The damping force and dynamic range of the proposed MR damper are enhanced by 55.82% and 62.21% compared to that of the traditional MR damper at the applied current of 1.5 A, respectively, thus highlighting its high vibration control ability. Full article
(This article belongs to the Special Issue Smart Materials in Robotics and Actuators)
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<p>Structural schematic of the MR damper: (<b>a</b>) Traditional MR damper; (<b>b</b>) Proposed MR damper. 1. Magnetic activated region, 2. Non-flux region, 3. Non-magnetic material, 4. Second outer gap, 5. First outer gap, 6. Middle gap, 7. Inner gap.</p> Full article ">Figure 2
<p>Schematic diagram of the MR damper with folded resistance gaps and bending magnetic circuit. 1. Piston rod, 2. End cover, 3. Cylinder, 4. Piston cover, 5. Inner magnetic sleeve, 6. Middle magnetic sleeve, 7. Outer magnetic sleeve. 8, Exciting coil, 9. Non-magnetic ring, 10. Magnetic semicircle, 11. Non-magnetic disk, 12. Magnetic core, 13. End shield.</p> Full article ">Figure 3
<p>Simplified magnetic circuit of the proposed MR damper. 1. Magnetic core, 2. Inner gap, 3. Inner magnetic sleeve, 4. Middle gap, 5. Middle magnetic sleeve, 6. First outer gap, 7. Outer magnetic sleeve, 8. Second outer gap, 9. Non-magnetic ring.</p> Full article ">Figure 4
<p>The performance curves of MR fluids: (<b>a</b>) <span class="html-italic">B</span>-<span class="html-italic">H</span> curve; (<b>b</b>) <span class="html-italic">τ</span>–<span class="html-italic">B</span> curve.</p> Full article ">Figure 5
<p>Axisymmetric model for the FEA: (<b>a</b>) Proposed MR damper; (<b>b</b>) Traditional MR damper.</p> Full article ">Figure 6
<p>Comparison of the magnetic flux lines: (<b>a</b>) Proposed MR damper; (<b>b</b>) Traditional MR damper.</p> Full article ">Figure 7
<p>Contours of the magnetic flux density of the both MR damper: (<b>a</b>) Proposed MR damper; (<b>b</b>) Traditional MR damper.</p> Full article ">Figure 8
<p>The comparison of the magnetic flux density between the proposed MR damper and the traditional MR damper.</p> Full article ">Figure 9
<p>Magnetic flux density of the proposed MR damper at each gap with various current inputs: (<b>a</b>) Inner gap and middle gap; (<b>b</b>) First outer gap and Second outer gap.</p> Full article ">Figure 10
<p>Average magnetic flux density with different applied current inputs.</p> Full article ">Figure 11
<p>Comparison of the damping force of the traditional damper and the proposed damper under different applied currents.</p> Full article ">Figure 12
<p>Proposed MR damper with folded resistance gaps and bending magnetic circuit: (<b>a</b>) Components; (<b>b</b>) Prototype.</p> Full article ">Figure 13
<p>Experimental test rig of MR damper: 1. Vibration excitation platform, 2. proposed MR damper, 3. controlled computer, 4. DC power supply, 5. electro-hydraulic servo controller.</p> Full article ">Figure 14
<p>Damping force under different amplitudes and frequencies: (<b>a</b>) Damping force under different amplitudes; (<b>b</b>) Damping force under different frequencies.</p> Full article ">Figure 15
<p>Damping force under different frequencies with the current of 1 A and the amplitude of 10 mm: (<b>a</b>) Damping force vs. displacement; (<b>b</b>) Damping force vs. velocity.</p> Full article ">Figure 16
<p>Damping force under different applied currents.</p> Full article ">Figure 17
<p>Simulated and experimental damping force under different applied currents.</p> Full article ">Figure 18
<p>Comparison of the damping performance between the proposed and the traditional MR damper: (<b>a</b>) Damping force versus current; (<b>b</b>) Dynamic range versus current.</p> Full article ">
20 pages, 10755 KiB  
Article
Investigation on the Opposing Jet in the Hypersonic Rarefied Flow over a Vehicle Based on the DSMC Method
by Yi Shen, Jun Zhang, Xiao Xu, Jing Liu, Zhaoming Zhang and Yanmei Jiao
Actuators 2022, 11(6), 164; https://doi.org/10.3390/act11060164 - 15 Jun 2022
Cited by 4 | Viewed by 2101
Abstract
In this paper, an opposing jet is applied to the space shuttle arc leading edge and the lifting body cone leading edge in the hypersonic condition of the rarefied flow field. The DSMC numerical algorithm is used to simulate and analyze the underlying [...] Read more.
In this paper, an opposing jet is applied to the space shuttle arc leading edge and the lifting body cone leading edge in the hypersonic condition of the rarefied flow field. The DSMC numerical algorithm is used to simulate and analyze the underlying working physics of the opposing jet. The results provide a reference for designing hypersonic vehicles in near space that reduce drag and protect against heat. Full article
(This article belongs to the Section Aircraft Actuators)
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<p>Schematic diagram of opposing jet structure: (<b>a</b>) Long penetration mode; (<b>b</b>) Short penetration mode.</p> Full article ">Figure 2
<p>Experimental diagram of opposing jet structure: (<b>a</b>) Blunt penetration mode; (<b>b</b>) Long penetration mode; (<b>c</b>) Short penetration mode.</p> Full article ">Figure 3
<p>Schematic diagram of molecular collision.</p> Full article ">Figure 4
<p>Two-dimensional ramp model (β = 35°).</p> Full article ">Figure 5
<p>The contour of two-dimensional ramp model (β = 35°): (<b>a</b>) Density; (<b>b</b>) Temperature; (<b>c</b>) Velocity.</p> Full article ">Figure 5 Cont.
<p>The contour of two-dimensional ramp model (β = 35°): (<b>a</b>) Density; (<b>b</b>) Temperature; (<b>c</b>) Velocity.</p> Full article ">Figure 6
<p>Wall coefficient distribution: (<b>a</b>) Friction coefficient; (<b>b</b>) Pressure coefficient.</p> Full article ">Figure 7
<p>Schematic view of the double ellipsoid structure.</p> Full article ">Figure 8
<p>Double ellipsoid mesh diagram (part).</p> Full article ">Figure 9
<p>Radius of curvature: (<b>a</b>) Upper surface; (<b>b</b>) Lower surface.</p> Full article ">Figure 10
<p>Contours of density distribution and streamline around the double ellipsoid opposing jet: (<b>a</b>) No opposing jet; (<b>b</b>) PR = 0.2; (<b>c</b>) PR = 0.4; (<b>d</b>) PR = 0.6; (<b>e</b>) PR = 0.8.</p> Full article ">Figure 11
<p>Position of reattachment point.</p> Full article ">Figure 12
<p>Double ellipsoid wall coefficient distribution: (<b>a</b>) Stanton number; (<b>b</b>) Pressure coefficient; (<b>c</b>) Friction coefficient.</p> Full article ">Figure 13
<p>Schematic diagram of lifting body structure.</p> Full article ">Figure 14
<p>Truncated cone mesh (part).</p> Full article ">Figure 15
<p>Contour of density nephogram and streamline of truncated cone: (<b>a</b>) No opposing jet; (<b>b</b>) PR = 0.2; (<b>c</b>) PR = 0.4; (<b>d</b>) PR = 0.6; (<b>e</b>) PR = 0.8.</p> Full article ">Figure 15 Cont.
<p>Contour of density nephogram and streamline of truncated cone: (<b>a</b>) No opposing jet; (<b>b</b>) PR = 0.2; (<b>c</b>) PR = 0.4; (<b>d</b>) PR = 0.6; (<b>e</b>) PR = 0.8.</p> Full article ">Figure 16
<p>Surface coefficient distribution of truncated cone: (<b>a</b>) Stanton number; (<b>b</b>) Pressure coefficient; (<b>c</b>) Friction coefficient.</p> Full article ">Figure 16 Cont.
<p>Surface coefficient distribution of truncated cone: (<b>a</b>) Stanton number; (<b>b</b>) Pressure coefficient; (<b>c</b>) Friction coefficient.</p> Full article ">
17 pages, 4522 KiB  
Article
Sound Driven Actuator Using Helmholtz Resonance
by Takeru Niwano and Mitsuharu Matsumoto
Actuators 2022, 11(6), 163; https://doi.org/10.3390/act11060163 - 15 Jun 2022
Cited by 1 | Viewed by 2165
Abstract
Repairing cracks in the concrete of a building is very important to ensure the safety of a nuclear power plant. However, repair work in areas with very strong radiation is very difficult. Many robots have been proposed to solve this problem. However, they [...] Read more.
Repairing cracks in the concrete of a building is very important to ensure the safety of a nuclear power plant. However, repair work in areas with very strong radiation is very difficult. Many robots have been proposed to solve this problem. However, they cannot operate wirelessly and have problems such as being left as debris in the event of an accident. To solve the problem, this paper investigates the feasibility of sound-driven robots. We focused on Helmholtz resonance to achieve this goal. In this paper, Helmholtz resonators were adopted as the drive source of the actuator, and a new prototype was created by devising the arrangement. We also examined the physical characteristics of the developed prototype. Unlike conventional actuators, the proposed device can be moved remotely simply by irradiating sound from the outside. The advantage of using sound waves is that the robot can move without being affected by electric or magnetic fields. Through some experiments, it was confirmed that the developed actuator can be moved remotely with sound. Full article
(This article belongs to the Section Control Systems)
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<p>Model of Helmholtz resonator.</p> Full article ">Figure 2
<p>Wind velocity vs. frequency at 5 mm sound hole.</p> Full article ">Figure 3
<p>Wind velocity vs. frequency at 5.5 mm sound hole.</p> Full article ">Figure 4
<p>Relationship between sound volume and wind speed.</p> Full article ">Figure 5
<p>Appearance of a ball (The diameter of the ball is 44 mm. Its weight is 2.5 g.).</p> Full article ">Figure 6
<p>Appearance of a ball between wheels (The diameter of the ball is 44 mm. The wheel diameter is 54 mm. Its weight is 5.5 g.).</p> Full article ">Figure 7
<p>Appearance of a ball with a fine-tipped cotton swab (The diameter of the ball is 44 mm. The cotton swab length is 20 mm. Its weight is 2.7 g.).</p> Full article ">Figure 8
<p>Appearance of a ball with a round-tipped cotton swab (The diameter of the ball is 44 mm. The cotton swab length is 16 mm. Its weight is 2.7 g.).</p> Full article ">Figure 9
<p>Experimental setup.</p> Full article ">Figure 10
<p>Actual movement of a ball with nothing attached.</p> Full article ">Figure 11
<p>Change in hole and direction of movement to rotation.</p> Full article ">Figure 12
<p>Actual movement of a ball with wheels.</p> Full article ">Figure 13
<p>Design of an improved actuator (The diameter of the ball is 44 mm. The radius of the wheel is 70 mm. The ball was installed at a position 45 mm from the center of the wheel. Its weight is 25.8 g.).</p> Full article ">Figure 14
<p>The force acting on the actuator by the wind.</p> Full article ">Figure 15
<p>Movement of an improved actuator.</p> Full article ">
18 pages, 15250 KiB  
Article
Research on PID Position Control of a Hydraulic Servo System Based on Kalman Genetic Optimization
by Ying-Qing Guo, Xiu-Mei Zha, Yao-Yu Shen, Yi-Na Wang and Gang Chen
Actuators 2022, 11(6), 162; https://doi.org/10.3390/act11060162 - 15 Jun 2022
Cited by 12 | Viewed by 4810
Abstract
With the wide application of hydraulic servo technology in control systems, the requirement of hydraulic servo position control performance is greater and greater. In order to solve the problems of slow response, poor precision, and weak anti-interference ability in hydraulic servo position controls, [...] Read more.
With the wide application of hydraulic servo technology in control systems, the requirement of hydraulic servo position control performance is greater and greater. In order to solve the problems of slow response, poor precision, and weak anti-interference ability in hydraulic servo position controls, a Kalman genetic optimization PID controller is designed. Firstly, aiming at the nonlinear problems such as internal leakage and oil compressibility in the hydraulic servo system, the mathematical model of the hydraulic servo system is established. By analyzing the working characteristics of the servo valve and hydraulic cylinder in the hydraulic servo system, the parameters in the mathematical model are determined. Secondly, a genetic algorithm is used to search the optimal proportional integral differential (PID) controller gain of the hydraulic servo system to realize the accurate control of valve-controlled hydraulic cylinder displacement in the hydraulic servo system. Under the positioning benchmark of step signal and sine wave signal, the PID algorithm and the genetic optimized PID algorithm are compared in the system simulation model established by Simulink. Finally, to solve the amplitude fluctuations caused by the GA optimized PID and reduce the influence of external disturbances, a Kalman filtering algorithm is added to the hydraulic servo system to reduce the amplitude fluctuations and the influence of external disturbances on the system. The simulation results show that the designed Kalman genetic optimization PID controller can be better applied to the position control of the hydraulic servo system. Compared with the traditional PID control algorithm, the PID algorithm optimized by genetic algorithm improves the system’s response speed and control accuracy; the Kalman filter is a good solution for the amplitude fluctuations caused by GA-optimized PID that reduces the influence of external disturbances on the hydraulic servo system. Full article
(This article belongs to the Special Issue Vibration Control and Structure Health Monitoring)
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<p>Schematic diagram of valve-controlled hydraulic servo system.</p> Full article ">Figure 2
<p>Valve-controlled hydraulic cylinder schematic.</p> Full article ">Figure 3
<p>Control flow chart of valve-controlled hydraulic cylinder.</p> Full article ">Figure 4
<p>Hydraulic servo system PID control.</p> Full article ">Figure 5
<p>PID Controller optimized by genetic algorithm.</p> Full article ">Figure 6
<p>Schematic diagram of GA-tuning PID parameters.</p> Full article ">Figure 7
<p>PID position control of hydraulic servo system based on Kalman genetic optimization.</p> Full article ">Figure 8
<p>Optimization of PID simulation diagram by GA.</p> Full article ">Figure 9
<p>Simulation results of the system without noise. (<b>a</b>) Step signal input; (<b>b</b>) Sinusoidal signal; (<b>c</b>) System simulation results under step signal input; (<b>d</b>) System simulation results under sinusoidal signal input.</p> Full article ">Figure 10
<p>Output of PID and GA-optimized PID controllers. (<b>a</b>) Controller output under step signal input; (<b>b</b>) Controller output under sinusoidal signal input.</p> Full article ">Figure 11
<p>System Simulation Diagram of Kalman filter-optimized genetic PID.</p> Full article ">Figure 12
<p>0.002 energy white noise.</p> Full article ">Figure 13
<p>System simulation results under 0.002 energy white noise. (<b>a</b>) System simulation results under step signal input; (<b>b</b>) System simulation results under sinusoidal signal input.</p> Full article ">Figure 14
<p>Output of PID and GA-optimized PID controllers under external disturbances. (<b>a</b>) Controller output under step signal input; (<b>b</b>) Controller output under sinusoidal signal input.</p> Full article ">
18 pages, 10715 KiB  
Article
Binary Controller Based on the Electrical Activity Related to Head Yaw Rotation
by Enrico Zero, Chiara Bersani and Roberto Sacile
Actuators 2022, 11(6), 161; https://doi.org/10.3390/act11060161 - 15 Jun 2022
Viewed by 1902
Abstract
A human machine interface (HMI) is presented to switch on/off lights according to the head left/right yaw rotation. The HMI consists of a cap, which can acquire the brain’s electrical activity (i.e., an electroencephalogram, EEG) sampled at 500 Hz on 8 channels with [...] Read more.
A human machine interface (HMI) is presented to switch on/off lights according to the head left/right yaw rotation. The HMI consists of a cap, which can acquire the brain’s electrical activity (i.e., an electroencephalogram, EEG) sampled at 500 Hz on 8 channels with electrodes that are positioned according to the standard 10–20 system. In addition, the HMI includes a controller based on an input–output function that can compute the head position (defined as left, right, and forward position with respect to yaw angle) considering short intervals (10 samples) of the signals coming from three electrodes positioned in O1, O2, and Cz. An artificial neural network (ANN) training based on a Levenberg–Marquardt backpropagation algorithm was used to identify the input–output function. The HMI controller was tested on 22 participants. The proposed classifier achieved an average accuracy of 88% with the best value of 96.85%. After calibration for each specific subject, the HMI was used as a binary controller to verify its ability to switch on/off lamps according to head turning movement. The correct prediction of the head movements was greater than 75% in 90% of the participants when performing the test with open eyes. If the subjects carried out the experiments with closed eyes, the prediction accuracy reached 75% of correctness in 11 participants out of 22. One participant controlled the light system in both experiments, open and closed eyes, with 100% success. The control results achieved in this work can be considered as an important milestone towards humanoid neck systems. Full article
(This article belongs to the Special Issue Intelligent Humanoid Mobile Robots)
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<p>System architecture.</p> Full article ">Figure 2
<p>Top vision of the layout for the experimental set environment.</p> Full article ">Figure 3
<p>EEG Enobio Cap.</p> Full article ">Figure 4
<p>Architecture of the proposed system.</p> Full article ">Figure 5
<p>Binary controller framework.</p> Full article ">Figure 6
<p>Comparison between the observed value and estimated value in the TDNN.</p> Full article ">
19 pages, 4983 KiB  
Article
Performance-Optimized Dielectric Elastomer Actuator System with Scalable Scissor Linkage Transmission
by Daniel Bruch, Tobias Pascal Willian, Hendrik Cornelius Schäfer and Paul Motzki
Actuators 2022, 11(6), 160; https://doi.org/10.3390/act11060160 - 14 Jun 2022
Cited by 4 | Viewed by 2683
Abstract
Thanks to their outstanding properties, in the last few years Dielectric Elastomer Actuators (DEAs) have increasingly attracted the interest of the scientific community and generated a surge in the effort devoted to their industrialization. Compared to conventional actuator systems, DEAs are based on [...] Read more.
Thanks to their outstanding properties, in the last few years Dielectric Elastomer Actuators (DEAs) have increasingly attracted the interest of the scientific community and generated a surge in the effort devoted to their industrialization. Compared to conventional actuator systems, DEAs are based on inexpensive and widely available polymeric materials, which make them potentially attractive from a market perspective. However, DEA systems with a given layout and dimensions have a fixed force-stroke response that is only suitable for a specific load profile. This leads to a wide variety of designs combined with small production volumes and high costs, limiting the competitive advantage. This work addresses this issue by proposing a combination of DEA systems with compliant scissor linkage transmission mechanisms, which provide linear stroke and force scaling and simultaneously maintain performance optimization by leaving the convertible energy density of the DEA unaffected. For this purpose, three systems are designed, based on a same strip-shaped DEA combined with inclined buckled beam biasing mechanisms. Two of the systems are coupled with scissor linkages that offer transmission ratios of 3:1 and 1:3, respectively, to adapt the system to different load profiles. The system design is explained in detail, and the functional principle is validated through experiments. Full article
(This article belongs to the Special Issue Smart Dielectric Elastomer Actuator and Sensor Systems)
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<p>Schematic illustration of a DEA in the inactive state on the <b>left</b>, in comparison to the active state on the <b>right</b>.</p> Full article ">Figure 2
<p>(<b>a</b>) Schematic concept illustration of a generic DEA system coupled to stroke magnifying and stroke reducing scissor linkages with input strokes <math display="inline"><semantics> <mrow> <mo>Δ</mo> <msub> <mi>x</mi> <mrow> <mi>i</mi> <mi>n</mi> </mrow> </msub> </mrow> </semantics></math> and output strokes <math display="inline"><semantics> <mrow> <mo>Δ</mo> <msub> <mi>x</mi> <mrow> <mi>o</mi> <mi>u</mi> <mi>t</mi> </mrow> </msub> </mrow> </semantics></math>, as well as (<b>b</b>) corresponding generic force-stroke characteristics for different transmission ratios.</p> Full article ">Figure 3
<p>(<b>a</b>) Generic illustration of a SIP system coupled with a PBS in comparison with a system based on a similar SIP biased with an NBS, and (<b>b</b>) qualitative force-stroke curves for both systems.</p> Full article ">Figure 4
<p>Kinematic chain of a scissor linkage with link lengths of <math display="inline"><semantics> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <msub> <mi>l</mi> <mn>2</mn> </msub> </mrow> </semantics></math>, rotation angle <math display="inline"><semantics> <mi>φ</mi> </semantics></math>, input stroke <math display="inline"><semantics> <mrow> <mo>Δ</mo> <msub> <mi>x</mi> <mrow> <mi>i</mi> <mi>n</mi> </mrow> </msub> </mrow> </semantics></math>, output stroke <math display="inline"><semantics> <mrow> <mo>Δ</mo> <msub> <mi>x</mi> <mrow> <mi>o</mi> <mi>u</mi> <mi>t</mi> </mrow> </msub> </mrow> </semantics></math> and corresponding forces <math display="inline"><semantics> <mrow> <msub> <mi>F</mi> <mrow> <mi>i</mi> <mi>n</mi> </mrow> </msub> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <msub> <mi>F</mi> <mrow> <mi>o</mi> <mi>u</mi> <mi>t</mi> </mrow> </msub> </mrow> </semantics></math> in (<b>a</b>) an inverting transmission configuration and in (<b>b</b>) a non-inverting configuration.</p> Full article ">Figure 5
<p>(<b>a</b>) Screen-print layout of the SIP which is alternately stacked with thin copper strips in a 4-layer layout, and sandwiched in between rigid clamps, as shown in (<b>b</b>) CAD explosion and (<b>c</b>) CAD assembly. (<b>d</b>) Photo of a cut-out sample mounted on a tensile test setup.</p> Full article ">Figure 6
<p>Inclined and centrally loaded buckled beam NBS shown as (<b>a</b>) CAD assembly and (<b>b</b>) schematic illustration with final geometrical construction parameters given (values with no unit in mm).</p> Full article ">Figure 7
<p>(<b>a</b>) CAD of one-piece scissor linkage mechanism with a non-inversing transmission configuration, where input and output sides can be swapped, and (<b>b</b>) detailed view of the design of a TPU joint and PLA connector and link.</p> Full article ">Figure 8
<p>CAD of the SIP system assembly with (<b>a</b>) view on the scissor linkage transmission side, and (<b>b</b>) view to the SIP-NBS side.</p> Full article ">Figure 9
<p>CAD comparison of the realized systems with the stroke-reducing transmission on the <b>left</b>, the system without transmission mechanism in the <b>middle</b>, and the stroke-magnifying transmission on the <b>right</b>.</p> Full article ">Figure 10
<p>(<b>a</b>) Schematic illustration of the tensile test setup for SIP characterization with different voltages applied and (<b>b</b>) corresponding measurement results in a force-displacement diagram.</p> Full article ">Figure 11
<p>(<b>a</b>) SIP system design curves with the SIP working against inclined and centrally loaded buckled beam NBS and weight of moving components, with (<b>b</b>) comparison of FE-simulation to measurement results of the NBS reaction force, and (<b>c</b>) a detailed view of the mechanical stresses in the beam cross-section. (<b>d</b>) Schematic illustration of the beam characterization setup.</p> Full article ">Figure 12
<p>Illustration of the setup for the characterization of the scissor linkage mechanisms: (<b>a</b>) schematic, (<b>b</b>) photo, (<b>c</b>) measurement results for the stroke transmission factor, (<b>d</b>) results for the reaction force measured on the input side.</p> Full article ">Figure 13
<p>(<b>a</b>) Schematic illustration of the setup for characterization of the SIP system stroke with (<b>b</b>) corresponding photo, (<b>c</b>) measurement results for voltage and stroke of the SIP-NBS system without transmission mechanism, and (<b>d</b>) a comparison of the strokes of the different realized systems.</p> Full article ">
13 pages, 3957 KiB  
Article
Design of a Panoramic Scanning Device Based on a Piezoelectric Ceramic Stack Actuator and Friction Transmission
by Minpeng Dai, Hao Ding, Chenwei Huang, Yi Zhu and Ming Wang
Actuators 2022, 11(6), 159; https://doi.org/10.3390/act11060159 - 13 Jun 2022
Cited by 1 | Viewed by 2286
Abstract
In view of the complex structure and inaccurate positioning capabilities of the existing panoramic scanning system, a panoramic scanning device based on a piezoelectric ceramic stack actuator and friction transmission was designed. In our model, the output displacement of the piezoelectric ceramics is [...] Read more.
In view of the complex structure and inaccurate positioning capabilities of the existing panoramic scanning system, a panoramic scanning device based on a piezoelectric ceramic stack actuator and friction transmission was designed. In our model, the output displacement of the piezoelectric ceramics is amplified by a bridge-type flexure hinge and applied to a shaft by friction to achieve panoramic scanning imaging. The mathematical model of the device was established, and the working characteristics were analyzed. The analysis demonstrated that the linear displacement increment of the shaft is a superposition. A modality simulation was performed, and the simulation results show that the designed device works normally at a frequency of 511.5 Hz. The test results indicated that the displacement of the actuator can reach 6 μm at an input voltage of 100 V. Moreover, the laser scanning results showed that the designed device can perform panoramic scanning imaging, which meets the requirements for use on the high-speed imaging system. Full article
(This article belongs to the Section Miniaturized and Micro Actuators)
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<p>Overall design of panoramic scanning imaging device.</p> Full article ">Figure 2
<p>Simplified schematic diagram of the actuator.</p> Full article ">Figure 3
<p>The relationship between the linear displacement increment of the shaft and the applied voltage (T is the cycle of the applied triangular wave voltage).</p> Full article ">Figure 4
<p>Simulink model of the proposed panoramic scanning imaging actuator.</p> Full article ">Figure 5
<p>Modality of the actuator at different frequencies. (<b>a</b>) The vibration form of actuator when f = 245.42 Hz. (<b>b</b>) The vibration form of actuator when f = 511.49 Hz. (<b>c</b>) The vibration form of actuator when f = 603.3 Hz.</p> Full article ">Figure 5 Cont.
<p>Modality of the actuator at different frequencies. (<b>a</b>) The vibration form of actuator when f = 245.42 Hz. (<b>b</b>) The vibration form of actuator when f = 511.49 Hz. (<b>c</b>) The vibration form of actuator when f = 603.3 Hz.</p> Full article ">Figure 6
<p>Characteristic test system schematic diagram of the proposed device.</p> Full article ">Figure 7
<p>The test result of the extension of the proposed actuator. (<b>a</b>) The relationship between <math display="inline"><semantics> <mrow> <mo>Δ</mo> <msub> <mi>L</mi> <mn>2</mn> </msub> </mrow> </semantics></math> and time; (<b>b</b>) the relationship between <math display="inline"><semantics> <mrow> <mo>Δ</mo> <msub> <mi>L</mi> <mn>2</mn> </msub> </mrow> </semantics></math> and input voltage.</p> Full article ">Figure 8
<p>Laser scanning test system.</p> Full article ">Figure 9
<p>The relationship curve between the linear displacement of the shaft and time. (<b>a</b>) Within three periods; (<b>b</b>) within 3 s.</p> Full article ">Figure 10
<p>The experimental setup of the velocity matching experiment.</p> Full article ">
15 pages, 2644 KiB  
Article
Numerical Study of the Fish-like Robot Swimming in Fluid with High Reynolds Number: Immersed Boundary Method
by Jun Zhang, Zhichao Lv, Haobo Hua, Chunming Zhang, Haiyang Yu and Yanmei Jiao
Actuators 2022, 11(6), 158; https://doi.org/10.3390/act11060158 - 13 Jun 2022
Cited by 2 | Viewed by 1886
Abstract
Fish-like robots have been widely used in intelligent surveillance and investigation because of their high swimming efficiency and low traveling noise. Numerical simulations are usually selected to simulate the movement modes and hydrodynamic characteristics of fish-like robots during design and manufacture. However, the [...] Read more.
Fish-like robots have been widely used in intelligent surveillance and investigation because of their high swimming efficiency and low traveling noise. Numerical simulations are usually selected to simulate the movement modes and hydrodynamic characteristics of fish-like robots during design and manufacture. However, the body-fitted grid method traditionally utilized in numerical simulations often has difficulty dealing with moving solid boundaries. In this work, the immersed boundary method, superior in handling the moving boundary conditions, is employed to simulate the movement of a fish-like robot swimming in high Reynolds number flows in combination with the RANS turbulence model. The numerical method is first validated using a fluid flowing over a square block, and the corresponding results are in good agreement with the ones reported in reference. Then, the swing of the fish-like robot under three different Reynolds numbers is studied. The lift coefficient and the drag coefficient of the fish-like robot decrease with increasing the Reynolds number. This paper provides remarkable support for future designs and applications of fish-like robots. Full article
(This article belongs to the Section Actuators for Robotics)
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<p>Schematic diagram of virtual boundary layer.</p> Full article ">Figure 2
<p>Simulation domain of flow over a square object.</p> Full article ">Figure 3
<p>Contours of vorticity, turbulent kinetic energy, and turbulent dissipation. (<b>a</b>) Vorticity; (<b>b</b>) turbulent kinetic energy; (<b>c</b>) turbulent dissipation rate.</p> Full article ">Figure 4
<p>The lift and the drag coefficients of the flow over a square object. (<b>a</b>) The lift coefficient <math display="inline"><semantics> <mrow> <msub> <mi>C</mi> <mi>l</mi> </msub> </mrow> </semantics></math>; (<b>b</b>) the drag coefficient <span class="html-italic">C<sub>d</sub></span>.</p> Full article ">Figure 5
<p>Fish body appearance model.</p> Full article ">Figure 6
<p>Simulation domain and the corresponding boundary conditions.</p> Full article ">Figure 7
<p>Length and swing range of the fish-like robot.</p> Full article ">Figure 8
<p>Lift and drag coefficients at different Reynolds numbers. (<b>a</b>) The lift coefficient <math display="inline"><semantics> <mrow> <msub> <mi>C</mi> <mi>l</mi> </msub> </mrow> </semantics></math>; (<b>b</b>) the drag coefficient <span class="html-italic">C<sub>d</sub></span>.</p> Full article ">Figure 9
<p>Contours of vorticity at different Reynolds numbers. (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>R</mi> <mi>e</mi> <mo>=</mo> <mn>5000</mn> </mrow> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>R</mi> <mi>e</mi> <mo>=</mo> <mn>50</mn> <mo>,</mo> <mn>000</mn> </mrow> </semantics></math>; (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>R</mi> <mi>e</mi> <mo>=</mo> <mn>500</mn> <mo>,</mo> <mn>000</mn> </mrow> </semantics></math>.</p> Full article ">Figure 10
<p>Contours of velocity along x-direction at different Reynolds numbers. (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>R</mi> <mi>e</mi> <mo>=</mo> <mn>5000</mn> </mrow> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>R</mi> <mi>e</mi> <mo>=</mo> <mn>50</mn> <mo>,</mo> <mn>000</mn> </mrow> </semantics></math>; (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>R</mi> <mi>e</mi> <mo>=</mo> <mn>500</mn> <mo>,</mo> <mn>000</mn> </mrow> </semantics></math>.</p> Full article ">Figure 11
<p>Pressure contours at different Reynolds numbers. (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>R</mi> <mi>e</mi> <mo>=</mo> <mn>5000</mn> </mrow> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>R</mi> <mi>e</mi> <mo>=</mo> <mn>50</mn> <mo>,</mo> <mn>000</mn> </mrow> </semantics></math>; (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>R</mi> <mi>e</mi> <mo>=</mo> <mn>500</mn> <mo>,</mo> <mn>000</mn> </mrow> </semantics></math>.</p> Full article ">
18 pages, 5482 KiB  
Article
Vibration Isolation Performance of an Adaptive Magnetorheological Elastomer-Based Dynamic Vibration Absorber
by Young Choi and Norman M. Wereley
Actuators 2022, 11(6), 157; https://doi.org/10.3390/act11060157 - 12 Jun 2022
Cited by 9 | Viewed by 3431
Abstract
This study evaluates the vibration isolation performance of an adaptive magnetorheological elastomer (MRE)-based dynamic vibration absorber (MRE-DVA) for mitigating the high frequency vibrations (100–250 Hz) of target devices. A simple and effective MRE-DVA design was presented and its vibration isolation performance was experimentally [...] Read more.
This study evaluates the vibration isolation performance of an adaptive magnetorheological elastomer (MRE)-based dynamic vibration absorber (MRE-DVA) for mitigating the high frequency vibrations (100–250 Hz) of target devices. A simple and effective MRE-DVA design was presented and its vibration isolation performance was experimentally measured. A cylindrical shaped MRE pad was configured to be operated in shear mode and also worked as a semi-actively tunable spring for achieving adaptive DVA. A complex stiffness analysis for the damper force cycle was conducted and it was experimentally observed that the controllable dynamic stiffness range of the MRE-DVA was greater than two over the tested frequency range. The transmissibility of a target system was measured and used as a performance index to evaluate its vibration isolation performance. It was also experimentally demonstrated that a better vibration isolation performance of the target device exposed to the high frequency vibrations could be achieved by using the adaptive MRE-DVA. Full article
(This article belongs to the Special Issue Active, Semi-active and Passive Vibration Control)
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<p>Peak first mode frequency versus adjustable first mode frequency range of a target system of most reported studies on adaptive MRE-DVAs (refer to <a href="#actuators-11-00157-t001" class="html-table">Table 1</a>). Here, “UMD” implies this study.</p> Full article ">Figure 2
<p>Schematic of the magnetorheological elastomer (MRE)-based dynamic vibration absorber (MRE-DVA): (<b>a</b>) at stationary status and (<b>b</b>) at dynamic status.</p> Full article ">Figure 3
<p>One example of the analytical electromagnetic characteristics of the MRE-DVA at an applied current input of 0.7 A: (<b>a</b>) magnetic field contour (2 mm gap case) and (<b>b</b>) magnetic density versus bobbin length.</p> Full article ">Figure 4
<p>Analytical magnetic flux density as a function of the applied current for the top and bottom active lengths of the MRE-DVA: (<b>a</b>) for the top active length (upper MRE pad) and (<b>b</b>) for the bottom active length (lower MRE pad).</p> Full article ">Figure 5
<p>Photograph of the fabricated MRE-DVA.</p> Full article ">Figure 6
<p>Experimental setup for the damper force testing of the MRE-DVA.</p> Full article ">Figure 7
<p>Measured damper force of the MRE-DVA versus the displacement (for a 3 mm pad thickness): (<b>a</b>) at 0.1 Hz and (<b>b</b>) at 150 Hz.</p> Full article ">Figure 8
<p>Complex stiffness analysis of the MRE-DVA in the frequency domain (3 mm pad thickness): (<b>a</b>) dynamic stiffness, <math display="inline"><semantics> <mrow> <msub> <mi>K</mi> <mi>d</mi> </msub> <mrow> <mo>(</mo> <mi>ω</mi> <mo>,</mo> <mspace width="0.166667em"/> <mi mathvariant="normal">i</mi> <mo>)</mo> </mrow> </mrow> </semantics></math>, (<b>b</b>) loss factor, <math display="inline"><semantics> <mi>η</mi> </semantics></math>, (<b>c</b>) storage stiffness, <math display="inline"><semantics> <mrow> <msup> <mi>K</mi> <mo>′</mo> </msup> <mrow> <mo>(</mo> <mi>ω</mi> <mo>,</mo> <mspace width="0.166667em"/> <mi mathvariant="normal">i</mi> <mo>)</mo> </mrow> </mrow> </semantics></math>, (<b>d</b>) loss stiffness, <math display="inline"><semantics> <mrow> <msup> <mi>K</mi> <mrow> <mo>″</mo> </mrow> </msup> <mrow> <mo>(</mo> <mi>ω</mi> <mo>,</mo> <mspace width="0.166667em"/> <mi mathvariant="normal">i</mi> <mo>)</mo> </mrow> </mrow> </semantics></math> and (<b>e</b>) dynamic range, <math display="inline"><semantics> <mi>DR</mi> </semantics></math>.</p> Full article ">Figure 9
<p>Testing setup for frequency response measurement of the target system with the MRE-DVA.</p> Full article ">Figure 10
<p>Vibration isolation performance of the MRE-DVA (3 mm pad thickness).</p> Full article ">Figure 11
<p>Equivalent mechanical model of the MRE-DVA.</p> Full article ">Figure 12
<p>Simulated vibration isolation performance and identified system parameters of the MRE-DVA using the equivalent mechanical model: (<b>a</b>) simulated vibration isolation performance and (<b>b</b>) identified system parameters.</p> Full article ">Figure 13
<p>Effect of the MRE pad thicknesses on the vibration isolation performances of the MRE-DVAs: (<b>a</b>) 1 mm thickness and (<b>b</b>) 2 mm thickness.</p> Full article ">Figure 14
<p>Comparison of the minimum envelopes of the vibration isolation performances of the MRE-DVAs for three different MRE pad thicknesses.</p> Full article ">Figure 15
<p>Power consumption of the MRE-DVA.</p> Full article ">Figure A1
<p>Simulated vibration isolation performances of the MRE-DVAs using the equivalent mechanical model: (<b>a</b>) 1 mm thickness and (<b>b</b>) 2 mm thickness.</p> Full article ">
18 pages, 2522 KiB  
Article
Control-Force Spectrum Considering Both Natural Period and Damping Ratio for Active Base-Isolated Building
by Yinli Chen, Daiki Sato, Kou Miyamoto and Jinhua She
Actuators 2022, 11(6), 156; https://doi.org/10.3390/act11060156 - 11 Jun 2022
Cited by 2 | Viewed by 1995
Abstract
The active structural control (ASC) has been applied to base-isolated buildings to achieve a high-damping system. The critical step for designing an ASC system is selecting control parameters and isolation parameters that satisfy the design restrictions. However, the conventional methods are limited in [...] Read more.
The active structural control (ASC) has been applied to base-isolated buildings to achieve a high-damping system. The critical step for designing an ASC system is selecting control parameters and isolation parameters that satisfy the design restrictions. However, the conventional methods are limited in theoretically estimating the maximum control force, which requires great demand for trial-and-error approaches and numerical simulations. This paper constructed the equivalent model of the feedback control system that theoretically expresses the dependence of vibration characteristics (natural period and damping ratio) of the control system on the feedback gain. Then, the control-force spectrum is proposed that estimates the maximum control force for a feedback control system, adjusting both the natural period and damping ratio of the control system. The maximum responses and control force are estimated without additional numerical simulations and trial-and-error approaches using the equivalent model and control-force spectrum. Moreover, a design method was devised for determining the allowance range of the vibration characteristics of structures (damping ratio and natural period) and controllers that satisfy the design limitations (maximum responses and maximum control force). The design method does not require trial-and-error and numerical simulations, thus simplifying the design procedure. Finally, this paper uses numerical examples and a design example to verify the validity of the control-force spectrum and design method. Full article
(This article belongs to the Special Issue Active, Semi-active and Passive Vibration Control)
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<p>Mathematical model (active model).</p> Full article ">Figure 2
<p>Block diagram of control system.</p> Full article ">Figure 3
<p>Equivalent model of (<b>a</b>) control system, (<b>b</b>) equivalent model <math display="inline"><semantics> <mfenced separators="" open="(" close=")"> <mover accent="true"> <mi>x</mi> <mo>^</mo> </mover> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <mi>x</mi> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> </mfenced> </semantics></math>.</p> Full article ">Figure 4
<p>Tatf NS wave (PGV = 75.0 cm/s): (<b>a</b>) accelerogram, (<b>b</b>) pseudo–velocity response spectrum.</p> Full article ">Figure 5
<p>El Centro 1940 NS wave (PGV = 75.0 cm/s): (<b>a</b>) accelerogram, (<b>b</b>) pseudo–velocity response spectrum.</p> Full article ">Figure 6
<p>JMA Kobe NS wave (PGV = 75.0 cm/s): (<b>a</b>) accelerogram, (<b>b</b>) pseudo–velocity response spectrum.</p> Full article ">Figure 7
<p>Code Hachinohe wave (1.5 times Level II of the Japan earthquake resistance design standard): (<b>a</b>) accelerogram, (<b>b</b>) pseudo–velocity response spectrum.</p> Full article ">Figure 8
<p>Control-force spectrum (<math display="inline"><semantics> <mrow> <msub> <mi>T</mi> <mi mathvariant="normal">s</mi> </msub> <mo>=</mo> <mn>4</mn> <mrow> <mspace width="3.33333pt"/> <mi mathvariant="normal">s</mi> </mrow> <mo>,</mo> <msub> <mi>ζ</mi> <mi mathvariant="normal">s</mi> </msub> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math>): (<b>a</b>) Taft NS, (<b>b</b>) El Centro 1940 NS, (<b>c</b>) JMA Kobe NS, and (<b>d</b>) Code Hachinohe.</p> Full article ">Figure 9
<p>Response spectra of Code Hachinohe wave: (<b>a</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mi mathvariant="normal">D</mi> </msub> </semantics></math>–<math display="inline"><semantics> <msub> <mi>S</mi> <mi mathvariant="normal">A</mi> </msub> </semantics></math> relationship, (<b>b</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mi mathvariant="normal">V</mi> </msub> </semantics></math>.</p> Full article ">Figure 10
<p>Control-force spectrum of Code Hachinohe wave (design example).</p> Full article ">Figure 11
<p>Time–history wave of design example (Code Hachinohe, <math display="inline"><semantics> <mrow> <msub> <mi>T</mi> <mi mathvariant="normal">s</mi> </msub> <mo>=</mo> <mn>5</mn> <mrow> <mspace width="3.33333pt"/> <mi mathvariant="normal">s</mi> </mrow> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>ζ</mi> <mi mathvariant="normal">s</mi> </msub> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>T</mi> <mi>eq</mi> </msub> <mo>=</mo> <mn>6</mn> <mrow> <mspace width="3.33333pt"/> <mi mathvariant="normal">s</mi> </mrow> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>ζ</mi> <mi>eq</mi> </msub> <mo>=</mo> <mn>0.40</mn> </mrow> </semantics></math>): (<b>a</b>) displacement response, (<b>b</b>) velocity response, (<b>c</b>) absolute acceleration response, and (<b>d</b>) shear-force coefficient of control force.</p> Full article ">Figure 12
<p>Force–displacement loop: shear-force coefficient of control force.</p> Full article ">Figure A1
<p>Accuracy of <math display="inline"><semantics> <msub> <mover accent="true"> <mi>S</mi> <mo>˜</mo> </mover> <mrow> <mi mathvariant="normal">C</mi> <mo>,</mo> <mi>ABS</mi> </mrow> </msub> </semantics></math> (<math display="inline"><semantics> <mrow> <msub> <mi>T</mi> <mi mathvariant="normal">s</mi> </msub> <mo>=</mo> <mn>4</mn> <mrow> <mspace width="3.33333pt"/> <mi mathvariant="normal">s</mi> </mrow> <mo>,</mo> <msub> <mi>ζ</mi> <mi mathvariant="normal">s</mi> </msub> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math>): (<b>a</b>) component 1 of No. 6 wave, (<b>b</b>) component 1 of No. 7 wave.</p> Full article ">Figure A2
<p>Accuracy of <math display="inline"><semantics> <msub> <mover accent="true"> <mi>S</mi> <mo>˜</mo> </mover> <mrow> <mi mathvariant="normal">C</mi> <mo>,</mo> <mi>SRSS</mi> </mrow> </msub> </semantics></math> (<math display="inline"><semantics> <mrow> <msub> <mi>T</mi> <mi mathvariant="normal">s</mi> </msub> <mo>=</mo> <mn>4</mn> <mrow> <mspace width="3.33333pt"/> <mi mathvariant="normal">s</mi> </mrow> <mo>,</mo> <msub> <mi>ζ</mi> <mi mathvariant="normal">s</mi> </msub> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math>): (<b>a</b>) component 1 of No. 6 wave, (<b>b</b>) component 1 of No. 7 wave.</p> Full article ">Figure A3
<p>Estimation error of control-force spectrum of FEMA waves (<math display="inline"><semantics> <mrow> <msub> <mi>T</mi> <mi mathvariant="normal">s</mi> </msub> <mo>=</mo> <mn>4</mn> <mrow> <mspace width="3.33333pt"/> <mi mathvariant="normal">s</mi> </mrow> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>ζ</mi> <mi mathvariant="normal">s</mi> </msub> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <msub> <mi>T</mi> <mi>eq</mi> </msub> </semantics></math>: 0.01∼10 s per 0.01 s): (<b>a</b>) <math display="inline"><semantics> <mrow> <msub> <mi>ζ</mi> <mi>eq</mi> </msub> <mo>=</mo> <mn>0.10</mn> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <msub> <mi>ζ</mi> <mi>eq</mi> </msub> <mo>=</mo> <mn>0.30</mn> </mrow> </semantics></math>, (<b>c</b>) <math display="inline"><semantics> <mrow> <msub> <mi>ζ</mi> <mi>eq</mi> </msub> <mo>=</mo> <mn>0.50</mn> </mrow> </semantics></math>, and (<b>d</b>) <math display="inline"><semantics> <mrow> <msub> <mi>ζ</mi> <mi>eq</mi> </msub> <mo>=</mo> <mn>0.70</mn> </mrow> </semantics></math>.</p> Full article ">Figure A3 Cont.
<p>Estimation error of control-force spectrum of FEMA waves (<math display="inline"><semantics> <mrow> <msub> <mi>T</mi> <mi mathvariant="normal">s</mi> </msub> <mo>=</mo> <mn>4</mn> <mrow> <mspace width="3.33333pt"/> <mi mathvariant="normal">s</mi> </mrow> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>ζ</mi> <mi mathvariant="normal">s</mi> </msub> <mo>=</mo> <mn>0.01</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <msub> <mi>T</mi> <mi>eq</mi> </msub> </semantics></math>: 0.01∼10 s per 0.01 s): (<b>a</b>) <math display="inline"><semantics> <mrow> <msub> <mi>ζ</mi> <mi>eq</mi> </msub> <mo>=</mo> <mn>0.10</mn> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <msub> <mi>ζ</mi> <mi>eq</mi> </msub> <mo>=</mo> <mn>0.30</mn> </mrow> </semantics></math>, (<b>c</b>) <math display="inline"><semantics> <mrow> <msub> <mi>ζ</mi> <mi>eq</mi> </msub> <mo>=</mo> <mn>0.50</mn> </mrow> </semantics></math>, and (<b>d</b>) <math display="inline"><semantics> <mrow> <msub> <mi>ζ</mi> <mi>eq</mi> </msub> <mo>=</mo> <mn>0.70</mn> </mrow> </semantics></math>.</p> Full article ">Figure A4
<p>Response spectra of Tatf NS: (<b>a</b>) displacement response spectrum and (<b>b</b>) velocity response spectrum.</p> Full article ">Figure A5
<p>Response spectra of El Centro 1940 NS: (<b>a</b>) displacement response spectrum and (<b>b</b>) velocity response spectrum.</p> Full article ">Figure A6
<p>Response spectra of JMA Kobe NS: (<b>a</b>) displacement response spectrum and (<b>b</b>) velocity response spectrum.</p> Full article ">Figure A7
<p>Response spectra of Code Hachinohe: (<b>a</b>) displacement response spectrum and (<b>b</b>) velocity response spectrum.</p> Full article ">
15 pages, 2780 KiB  
Article
Transonic Buffet Active Control with Local Smart Skin
by Kai Ren, Chuanqiang Gao, Fangqi Zhou and Weiwei Zhang
Actuators 2022, 11(6), 155; https://doi.org/10.3390/act11060155 - 10 Jun 2022
Cited by 2 | Viewed by 2152
Abstract
Transonic flight has high economic benefits, but the appearance of transonic buffet limits the flight envelope. The shock control bump currently used for transonic buffet suppression tends to degrade the aerodynamic performance of the non-buffeting state. In this study, a smart skin system [...] Read more.
Transonic flight has high economic benefits, but the appearance of transonic buffet limits the flight envelope. The shock control bump currently used for transonic buffet suppression tends to degrade the aerodynamic performance of the non-buffeting state. In this study, a smart skin system is used to eliminate the fluctuating load of transonic buffet by measuring the airfoil lift coefficient as the feedback signal and adjusting the local skin height using data-driven, model-free adaptive control. Since the actuator height is dynamically adjusted only after the occurrence of transonic buffet, the smart skin can completely suppress the fluctuating load and does not affect the aerodynamic performance in the non-buffeting state. The suppression effect of the proposed smart skin on transonic buffet is verified by numerical simulation of the flow. The simulation results show that due to the introduction of closed-loop control, the fluctuating load of transonic buffet can be effectively suppressed for different positions and maximum heights of the actuator. Even when the flow state changes, the robust smart skin system can also achieve the control goal. Therefore, smart skins combining flexible materials and control technologies have the potential to effectively improve the aerodynamic performance of aircraft. Full article
(This article belongs to the Special Issue Active Flow Control: Recent Advances in Fundamentals and Applications)
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Figure 1

Figure 1
<p>Diagram of smart skin micro actuator.</p> Full article ">Figure 2
<p>Comparison of pressure distribution on airfoil surface.</p> Full article ">Figure 3
<p>Comparison of transonic buffet onset boundary.</p> Full article ">Figure 4
<p>Lift coefficient time history.</p> Full article ">Figure 5
<p>Local pressure contours and streamlines of flow field at different moments: (<b>a</b>) moment <span class="html-italic">a</span>; (<b>b</b>) moment <span class="html-italic">b</span>; (<b>c</b>) moment <span class="html-italic">c</span>; (<b>d</b>) moment <span class="html-italic">d</span>.</p> Full article ">Figure 6
<p>Block diagram of model-free adaptive control system.</p> Full article ">Figure 7
<p>Time history of the system: (<b>a</b>) lift coefficient; (<b>b</b>) drag coefficient; (<b>c</b>) actuator height.</p> Full article ">Figure 8
<p>Flow field pressure contour and streamlines after control convergence.</p> Full article ">Figure 9
<p>Time history of the shock wave position and the height of the actuator.</p> Full article ">Figure 10
<p>Local pressure contours and streamlines of flow field at different moments: (<b>a</b>) moment <span class="html-italic">a’</span>; (<b>b</b>) moment <span class="html-italic">b’</span>; (<b>c</b>) moment <span class="html-italic">c’</span>; (<b>d</b>) moment <span class="html-italic">d’</span>.</p> Full article ">Figure 11
<p>Time history of the system (actuator range: 0.25~0.45): (<b>a</b>) lift coefficient; (<b>b</b>) actuator height.</p> Full article ">Figure 12
<p>Time history of the system (actuator range: 0.4~0.6): (<b>a</b>) lift coefficient; (<b>b</b>) actuator height.</p> Full article ">Figure 13
<p>Relationship between maximum height of actuator and crest chordwise position.</p> Full article ">Figure 14
<p>Influence of actuator height constraint <span class="html-italic">h<sub>s</sub></span> on dynamic characteristics of the control system: (<b>a</b>) time history of lift coefficient; (<b>b</b>) time history of actuator height.</p> Full article ">Figure 15
<p>Time history of the system (<span class="html-italic">M</span> = 0.73, <span class="html-italic">α</span> = 4.8°): (<b>a</b>) lift coefficient; (<b>b</b>) drag coefficient; (<b>c</b>) actuator height.</p> Full article ">Figure 16
<p>Time history of the system (<span class="html-italic">M</span> = 0.71, <span class="html-italic">α</span> = 5.5°): (<b>a</b>) lift coefficient; (<b>b</b>) drag coefficient; (<b>c</b>) actuator height.</p> Full article ">
26 pages, 4925 KiB  
Review
A Review on Thomson Coil Actuators in Fast Mechanical Switching
by Mohmmad Al-Dweikat, Jian Cui, Shuai Sun, Mingming Yang, Guogang Zhang and Yingsan Geng
Actuators 2022, 11(6), 154; https://doi.org/10.3390/act11060154 - 10 Jun 2022
Cited by 10 | Viewed by 5992
Abstract
With the rapid development of DC power systems and the increasing demand for DC circuit breakers, electromagnetic repulsive drives-based Thomson coil actuators (TCA) are widely investigated to provide the high-speed actuating required for ultra-fast mechanical switches, especially those used in hybrid DC circuit [...] Read more.
With the rapid development of DC power systems and the increasing demand for DC circuit breakers, electromagnetic repulsive drives-based Thomson coil actuators (TCA) are widely investigated to provide the high-speed actuating required for ultra-fast mechanical switches, especially those used in hybrid DC circuit breakers. The actuating mechanism is required to be fast, reliable, and economic. This article summarizes the development of Thomson coil actuators in circuit breakers in recent years, further illustrating the basic principles and the actuator topology. In addition, it discusses the various structural components of TCA and describes the utilized modeling and simulation methods. The main objective was to provide a comprehensive overview of the TCA field. Full article
(This article belongs to the Section High Torque/Power Density Actuators)
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Figure 1
<p>Schematic of a modular hybrid IGBT DC breaker.</p> Full article ">Figure 2
<p>Principle of coil–coil and coil–disk repulsion mechanism.</p> Full article ">Figure 3
<p>Transfer switch based on TCA, redrawn as depicted in [<a href="#B100-actuators-11-00154" class="html-bibr">100</a>].</p> Full article ">Figure 4
<p>Two-way TCA repulsion mechanism [<a href="#B71-actuators-11-00154" class="html-bibr">71</a>].</p> Full article ">Figure 5
<p>TCA utilizing a spring holding mechanism, redrawn as depicted in [<a href="#B48-actuators-11-00154" class="html-bibr">48</a>].</p> Full article ">Figure 6
<p>Schematic of di-stable spring mechanism: (<b>a</b>) redrawn as depicted in [<a href="#B71-actuators-11-00154" class="html-bibr">71</a>]; (<b>b</b>) Bi-stable spring working principle.</p> Full article ">Figure 7
<p>One-way and two-way disc springs’ principles.</p> Full article ">Figure 8
<p>Disc spring mechanism: (<b>a</b>) disc spring, redrawn as depicted in [<a href="#B66-actuators-11-00154" class="html-bibr">66</a>]; (<b>b</b>) buckling spring ribbons, redrawn as depicted in [<a href="#B85-actuators-11-00154" class="html-bibr">85</a>].</p> Full article ">Figure 9
<p>TCA utilizing permanent magnet (PM) holding mechanism, redrawn as depicted in [<a href="#B60-actuators-11-00154" class="html-bibr">60</a>].</p> Full article ">Figure 10
<p>TCA utilizing a gas pressure buffer, redrawn as depicted in [<a href="#B109-actuators-11-00154" class="html-bibr">109</a>].</p> Full article ">Figure 11
<p>Single pulse control circuits of TCA. (<b>a</b>) Single pulse drive circuit freewheeling the coil; (<b>b</b>) single pulse drive circuit freewheeling coil-thyristor; (<b>c</b>) di-directional drive circuit.</p> Full article ">Figure 12
<p>Multiple pulse control circuits of TCA; (<b>a</b>) two-stage pulse circuit; (<b>b</b>) pulse-forming drive circuit.</p> Full article ">Figure A1
<p>ECM schematic of the TCA drive, buffer, and armature circuits.</p> Full article ">Figure A2
<p>Partition principle of the armature.</p> Full article ">Figure A3
<p>FEM geometry showing the drive coil, armature, and buffer coil. (<b>a</b>) FEM coupling; (<b>b</b>) 2D, axial-symmetric geometry configuration and materials.</p> Full article ">
23 pages, 6157 KiB  
Article
Design and Experiment Evaluation of Load Distribution on the Dual Motors in Cam-Based Variable Stiffness Actuator with Helping Mode
by Fanghua Mei, Shusheng Bi, Yueri Cai and Hanjun Gao
Actuators 2022, 11(6), 153; https://doi.org/10.3390/act11060153 - 8 Jun 2022
Viewed by 2356
Abstract
This paper presents a novel cam-based variable stiffness actuator (VSA). It significantly differs from its counterparts in that the external load distributes on its two motors with a small difference. It is a feasible method to improve VSA’s output power, especially in compact [...] Read more.
This paper presents a novel cam-based variable stiffness actuator (VSA). It significantly differs from its counterparts in that the external load distributes on its two motors with a small difference. It is a feasible method to improve VSA’s output power, especially in compact joints, such as rehabilitation devices. The stiffness adjustment involves a spring-balanced crank-slider mechanism with a variable-length base frame. Its tunable node is the common node for force decomposition, synthesis, stiffness adjustment, and position control by setting it at the common groove of two differential variable-pitch cams. The paper establishes analytical expressions among the pressure angle of the cam pitch curve, load distribution, and its crucial design indexes and constraints. Based on this, the pitch curve synthesis method is put forward to optimize the load distribution. In addition, a reasonable tradeoff can be easily made by locally adjusting the cam pressure angle. So, the dual motors can work against the output load together in the same direction with a close amount. In the fabricated prototype, current stratification caused by the unstable friction direction has been observed. The estimation results of motor frictionless current matched the designed load distribution behavior. Full article
(This article belongs to the Special Issue Actuation Solutions for Wearable Robots)
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<p>VSA categories based on load distribution (<b>a</b>) Independent mode; (<b>b</b>) Antagonistic mode; (<b>c</b>) Helping mode (the type proposed).</p> Full article ">Figure 2
<p>The proposed VSA design (<b>a</b>) Working principle; (<b>b</b>) Exploded view of the CAD model.</p> Full article ">Figure 3
<p>Load distribution modeling schematics (<b>a</b>) Cam curve in the part polar coordinate system; (<b>b</b>) Static forces at the common node.</p> Full article ">Figure 4
<p>Two reconfigurable configurations (<b>a</b>) Configuration I: low stiffness with limited range (<span class="html-italic">AB &gt; OA</span>); (<b>b</b>) Configuration II: infinite stiffness range (<span class="html-italic">AB &lt; OA</span>).</p> Full article ">Figure 5
<p>Stiffness characteristic and variation of output torque: (<b>a</b>) configuration I: low stiffness with limited range (<span class="html-italic">AB</span> <b>&gt;</b> <span class="html-italic">OA</span>); (<b>b</b>) Configuration II: infinite stiffness range (<span class="html-italic">AB</span> <b>&lt;</b> <span class="html-italic">OA</span>).</p> Full article ">Figure 6
<p>Numerical synthesis of the cam pitch curve pressure angle.</p> Full article ">Figure 7
<p>Curvature radius result after tradeoff design.</p> Full article ">Figure 8
<p>Comparative analysis of the pitch curve shape.</p> Full article ">Figure 9
<p>Comparative analysis of pressure angle on the pitch curve.</p> Full article ">Figure 10
<p>Load ratio comparison of configuration I (variable pitch vs. uniform pitch).</p> Full article ">Figure 11
<p>Load ratio comparison of configuration II (variable pitch vs. uniform pitch).</p> Full article ">Figure 12
<p>Test platform (<b>a</b>) Shape of cam <span class="html-italic">C</span><sub>1</sub> (<b>b</b>) Two different positions of common groove for two reconfigurable configurations of VSA (<b>c</b>) Deformed VSA of configuration II (<b>d</b>) Structure of cam followers (<b>e</b>) Deformed VSA of configuration I (<b>f</b>) Undeformed VSA of configuration I (<b>g</b>) Overall structure of the test platform.</p> Full article ">Figure 13
<p>Current stratification of motor <span class="html-italic">M</span><sub>1</sub> (<span class="html-italic">AB</span> &gt; <span class="html-italic">OA</span>, <span class="html-italic">ρ</span> = 0.048 m).</p> Full article ">Figure 14
<p>Current stratification of motor <span class="html-italic">M</span><sub>2</sub> (<span class="html-italic">AB</span> &gt; <span class="html-italic">OA</span>, <span class="html-italic">ρ</span> = 0.048 m).</p> Full article ">Figure 15
<p>Current estimation for cam <span class="html-italic">C</span><sub>1</sub> (<span class="html-italic">AB</span> &gt; <span class="html-italic">OA</span>, <span class="html-italic">ρ</span> = 0.048 m).</p> Full article ">Figure 16
<p>Current estimation for cam <span class="html-italic">C</span><sub>2</sub> (<span class="html-italic">AB</span> &gt; <span class="html-italic">OA</span>, <span class="html-italic">ρ</span> = 0.048 m).</p> Full article ">Figure 17
<p>Frictionless current estimation for cam <span class="html-italic">C</span><sub>1</sub> in configuration I.</p> Full article ">Figure 18
<p>Frictionless current estimation for cam <span class="html-italic">C</span><sub>2</sub> in configuration I.</p> Full article ">Figure 19
<p>Frictionless current estimation for cam <span class="html-italic">C</span><sub>1</sub> in configuration II.</p> Full article ">Figure 20
<p>Frictionless current estimation for cam <span class="html-italic">C</span><sub>2</sub> in configuration II.</p> Full article ">Figure 21
<p>Load ratio <span class="html-italic">ϕ</span> in configuration I (<span class="html-italic">AB</span> &gt; <span class="html-italic">OA</span>).</p> Full article ">Figure 22
<p>Load ratio <span class="html-italic">ϕ</span> in configuration II (<span class="html-italic">AB</span> &lt; <span class="html-italic">OA</span>).</p> Full article ">Figure 23
<p>Calculation results of the angle <span class="html-italic">β</span> with two configurations.</p> Full article ">Figure 24
<p>Influence of friction fluctuation in configuration I.</p> Full article ">Figure 25
<p>Influence of friction fluctuation in configuration II.</p> Full article ">Figure 26
<p>Current comparison with different deflection direction.</p> Full article ">Figure 27
<p>Load ratio estimation results in configuration I with <span class="html-italic">θ</span> &gt; 0.</p> Full article ">
9 pages, 1136 KiB  
Communication
Effect of Wearing Running Shoes on Lower Limb Kinematics by Using OpenSim Simulation Software
by Gunarajulu Renganathan, Hamidreza Barnamehei, Swagata Das and Yuichi Kurita
Actuators 2022, 11(6), 152; https://doi.org/10.3390/act11060152 - 6 Jun 2022
Cited by 7 | Viewed by 2740
Abstract
(1) Flatfoot is a common malformation in both children and adults, in which a proper arch fails to develop. This study aimed to see how over-the-counter running shoes improved the gait patterns of flatfoot patients. (2) Methods: Three healthy flatfoot subjects were included [...] Read more.
(1) Flatfoot is a common malformation in both children and adults, in which a proper arch fails to develop. This study aimed to see how over-the-counter running shoes improved the gait patterns of flatfoot patients. (2) Methods: Three healthy flatfoot subjects were included in the study. Flatfoot was diagnosed by a lateral talometatarsal angle of more than 4 degrees and a talocalcaneal angle of more than 30 degrees. All the patient data were captured using Vicon motion caption cameras. The subjects were allowed to walk at self-selected speeds with and without running shoes. (3) Results: Significant differences in lower limb kinematics were observed between barefoot and running shoe gait. In addition, by wearing the running shoes, the center of mass and lower limb kinematics changed. (4) Conclusion: The improvement in balance and control was clearly indicated, and the change in gait on the entire lower limb influenced normalizing the stresses of the foot with running shoes. These valuable results can be used for rehabilitation programs. Full article
(This article belongs to the Special Issue Soft Exoskeleton and Supernumerary Limbs for Human Augmentation)
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<p>Experimental setup used for GAIT measurements. The motion analysis lab for kinematics and kinetics measurements in Movafaghian (Sharif University of Technology, Tehran, Iran) consists of high-speed motion captures and force plates.</p> Full article ">Figure 2
<p>The anterior view, lateral view, and posterior view sides of the Rajagopal (2016) musculoskeletal model of OpenSim (Stanford University, Stanford, CA, USA, 4.3 version) consisting of surface markers, 37 degrees of freedom (20 DOFs in the lower body and 17 in the torso and upper body), 80 muscle–tendon actuators to actuate the lower limbs, and 17 torque actuators to simulate the gait.</p> Full article ">Figure 3
<p>Hip kinematics of flatfoot subject with and without running shoes. r-right; l-left; FE-flexion/extension; AA-abduction/adduction; RR-internal/external rotation.</p> Full article ">Figure 4
<p>Maximum hip joint angles of flatfoot subjects with and without shoes. r-right; l-left.</p> Full article ">Figure 5
<p>Knee kinematics of flatfoot subjects with and without shoes. Red line indicates mean knee joint angle with shoe group and Blue line indicated mean knee joint angle without shoe group.</p> Full article ">Figure 6
<p>Maximum knee joint angles of flatfoot subjects with and without shoes. r-right; l-left.</p> Full article ">Figure 7
<p>Ankle kinematics of flatfoot subjects with and without shoes. Red line indicates mean ankle joint angle with shoe group and Blue line indicated mean ankle joint angle without shoe group.</p> Full article ">Figure 8
<p>Maximum ankle (dorsiflexion) joint angles of flatfoot subjects with and without shoes. r-right; l-left.</p> Full article ">Figure 9
<p>COM variables (displacement and velocity) of flatfoot subjects with and without shoes. Red line indicates mean ankle joint angle with shoe group and Blue line indicated mean ankle joint angle without shoe group.</p> Full article ">
12 pages, 585 KiB  
Article
Data-Driven Predictive Control of Interconnected Systems Using the Koopman Operator
by Duvan Tellez-Castro, Camilo Garcia-Tenorio, Eduardo Mojica-Nava, Jorge Sofrony and Alain Vande Wouwer
Actuators 2022, 11(6), 151; https://doi.org/10.3390/act11060151 - 6 Jun 2022
Cited by 6 | Viewed by 2408
Abstract
Interconnected systems are widespread in modern technological systems. Designing a reliable control strategy requires modeling and analysis of the system, which can be a complicated, or even impossible, task in some cases. However, current technological developments in data sensing, processing, and storage make [...] Read more.
Interconnected systems are widespread in modern technological systems. Designing a reliable control strategy requires modeling and analysis of the system, which can be a complicated, or even impossible, task in some cases. However, current technological developments in data sensing, processing, and storage make data-driven control techniques an appealing alternative solution. In this work, a design methodology of a decentralized control strategy is developed for interconnected systems based only on local and interconnection time series. Then, the optimization problem associated with the predictive control design is defined. Finally, an extension to interconnected systems coupled through their input signals is discussed. Simulations of two coupled Duffing oscillators, a bipedal locomotion model, and a four water tank system show the effectiveness of the approach. Full article
(This article belongs to the Special Issue Model Predictive Control in Mechatronic, Robotic, and Networked Systems)
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<p>Control schematic for interconnected subsystems.</p> Full article ">Figure 2
<p>Free body scheme representation of two interconnected mechanical oscillators.</p> Full article ">Figure 3
<p>Comparison between the linear predictor and the original system—subsystem 1 (<b>top</b>) and subsystem 2 (<b>bottom</b>).</p> Full article ">Figure 4
<p>Closed-loop local phase-plane and inputs of the Duffing system.</p> Full article ">Figure 5
<p>Topology of the interconnection of the bipedal robot locomotion system.</p> Full article ">Figure 6
<p>Angle, angular velocity, and input of the bipedal locomotor.</p> Full article ">Figure 7
<p>Water tanks with two subsystems interconnected by the input.</p> Full article ">Figure 8
<p>Level control of the four-tank benchmark.</p> Full article ">
16 pages, 6626 KiB  
Article
Coupled Force–Position Control for Dynamic Contact Force Tracking in Uncertain Environment
by Xiaogang Song, Bing Li, Wenfu Xu and Zhisen Li
Actuators 2022, 11(6), 150; https://doi.org/10.3390/act11060150 - 5 Jun 2022
Cited by 2 | Viewed by 3029
Abstract
Both the position and force control of robots are needed in industrial manufacturing, such as in assembly and grinding, etc. In this paper, we concentrate on two issues. One is the system oscillation in traditional hybrid force–position control (HFPC) during switching between force [...] Read more.
Both the position and force control of robots are needed in industrial manufacturing, such as in assembly and grinding, etc. In this paper, we concentrate on two issues. One is the system oscillation in traditional hybrid force–position control (HFPC) during switching between force and position control because the diagonal elements in the selection matrix are either 0 or 1. Another issue is the poor force-tracking performance of conventional impedance control, which depends on accurate environmental models. To address these issues, a coupled force–position control (CFPC) method is presented in this paper by combining the proposed adaptive impedance control method with a modified HFPC method. The selection matrix S of HFPC is replaced with a weighted matrix Sw. A weighted matrix regulator is designed to realize smooth switching between position and force control by adjusting the matrix weights in real time, and an adaptive impedance control algorithm is proposed to improve the force-tracking performance in complex environments. To verify the feasibility of the CFPC method proposed in this paper, simulations and physical experiments were conducted. The results show that the CFPC method has the advantages of a better force-tracking performance and a smoother switching between position and force control compared to the traditional HFPC method. A grinding experiment was conducted to further compare the performances of the HFPC and CFPC methods. The roughness values of the ground plates were 0.059 μm for the HFPC method and 0.031 μm for the proposed CFPC method, which demonstrates that the proposed CFPC method has a better performance. Full article
(This article belongs to the Special Issue Mechanism Design and Control for Robotics)
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Figure 1

Figure 1
<p>Contact force model for estimation.</p> Full article ">Figure 2
<p>Control block diagram of the proposed CFPC method.</p> Full article ">Figure 3
<p>Adaptive impedance controller.</p> Full article ">Figure 4
<p>Simulations on plane surface. Force tracking using (<b>a</b>) the HFPC and (<b>b</b>) proposed CFPC methods. (<b>c</b>) Position tracking. (<b>d</b>) Weighted parameter <math display="inline"><semantics> <mrow> <msub> <mi>s</mi> <mrow> <mi>w</mi> <mi>i</mi> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 5
<p>Simulations on sloped surface. Force tracking using (<b>a</b>) the HFPC and (<b>b</b>) proposed CFPC methods. (<b>c</b>) Position tracking. (<b>d</b>) Weighted parameter <math display="inline"><semantics> <mrow> <msub> <mi>s</mi> <mrow> <mi>w</mi> <mi>i</mi> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 6
<p>Simulations on complex surface. Force tracking using (<b>a</b>) the HFPC and (<b>b</b>) proposed CFPC methods. (<b>c</b>) Position tracking. (<b>d</b>) Weighted parameter <math display="inline"><semantics> <mrow> <msub> <mi>s</mi> <mrow> <mi>w</mi> <mi>i</mi> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 7
<p>Schematic of the experimental platform.</p> Full article ">Figure 8
<p>Experimental platform when executing (<b>a</b>) force tracking on a sloped surface and (<b>b</b>) force tracking on curved surface, and (<b>c</b>) when grinding.</p> Full article ">Figure 9
<p>Experimental platform when executing force tracking on a complex surface.</p> Full article ">Figure 10
<p>Constant force-tracking experiment on a sloped surface. Force tracking using (<b>a</b>) the HFPC and (<b>b</b>) proposed CFPC methods. (<b>c</b>) Position tracking. (<b>d</b>) Weighted parameter <math display="inline"><semantics> <mrow> <msub> <mi>s</mi> <mrow> <mi>w</mi> <mi>i</mi> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 10 Cont.
<p>Constant force-tracking experiment on a sloped surface. Force tracking using (<b>a</b>) the HFPC and (<b>b</b>) proposed CFPC methods. (<b>c</b>) Position tracking. (<b>d</b>) Weighted parameter <math display="inline"><semantics> <mrow> <msub> <mi>s</mi> <mrow> <mi>w</mi> <mi>i</mi> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 11
<p>Variable force-tracking experiment on a sloped surface. Force tracking using (<b>a</b>) the HFPC and (<b>b</b>) proposed CFPC methods. (<b>c</b>) Position tracking. (<b>d</b>) Weighted parameter <math display="inline"><semantics> <mrow> <msub> <mi>s</mi> <mrow> <mi>w</mi> <mi>i</mi> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 12
<p>Constant force-tracking experiment on curved surface. Force tracking using (<b>a</b>) the HFPC and (<b>b</b>) proposed CFPC methods. (<b>c</b>) Position tracking. (<b>d</b>) Weighted parameter <math display="inline"><semantics> <mrow> <msub> <mi>s</mi> <mrow> <mi>w</mi> <mi>i</mi> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 12 Cont.
<p>Constant force-tracking experiment on curved surface. Force tracking using (<b>a</b>) the HFPC and (<b>b</b>) proposed CFPC methods. (<b>c</b>) Position tracking. (<b>d</b>) Weighted parameter <math display="inline"><semantics> <mrow> <msub> <mi>s</mi> <mrow> <mi>w</mi> <mi>i</mi> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 13
<p>Variable force-tracking experiment on a curved surface. Force tracking using (<b>a</b>) the HFPC and (<b>b</b>) proposed CFPC methods. (<b>c</b>) Position tracking. (<b>d</b>) Weighted parameter <math display="inline"><semantics> <mrow> <msub> <mi>s</mi> <mrow> <mi>w</mi> <mi>i</mi> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 14
<p>Force-tracking experiment on a complex surface. Force tracking using (<b>a</b>) the HFPC and (<b>b</b>) proposed CFPC methods. (<b>c</b>) Position tracking. (<b>d</b>) Weighted parameter <math display="inline"><semantics> <mrow> <msub> <mi>s</mi> <mrow> <mi>w</mi> <mi>i</mi> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 15
<p>Grinding experiment on the plane. Force tacking using (<b>a</b>) the HFPC and (<b>b</b>) proposed CFPC methods. (<b>c</b>) Position tracking. (<b>d</b>) Weighted parameter <math display="inline"><semantics> <mrow> <msub> <mi>s</mi> <mrow> <mi>w</mi> <mi>i</mi> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 15 Cont.
<p>Grinding experiment on the plane. Force tacking using (<b>a</b>) the HFPC and (<b>b</b>) proposed CFPC methods. (<b>c</b>) Position tracking. (<b>d</b>) Weighted parameter <math display="inline"><semantics> <mrow> <msub> <mi>s</mi> <mrow> <mi>w</mi> <mi>i</mi> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 16
<p>(<b>a</b>) Grinding experiment results and (<b>b</b>) measured roughness from the HFPC (left photograph) and proposed CFPC (right photograph) methods.</p> Full article ">
10 pages, 4354 KiB  
Article
Novel Magnetic Circuit Design and Acceleration Calculation of Horizontal Linear Vibration Motor
by Zhixiong Jiang, Kihong Park and Sangmoon Hwang
Actuators 2022, 11(6), 149; https://doi.org/10.3390/act11060149 - 2 Jun 2022
Cited by 1 | Viewed by 2428
Abstract
This study proposes a novel magnetic circuit design to reduce the size of horizontal linear vibration motors (HLVMs) used in vehicle touchscreens. The HLVM prototype uses two thick permanent magnets to create a magnetic circuit below the voice coil; however, the novel design [...] Read more.
This study proposes a novel magnetic circuit design to reduce the size of horizontal linear vibration motors (HLVMs) used in vehicle touchscreens. The HLVM prototype uses two thick permanent magnets to create a magnetic circuit below the voice coil; however, the novel design places four thin permanent magnets above and below the voice coil. Moreover, the coil position has been changed to a yoke center to create an effective magnetic circuit with short magnets. Compared with the vertical linear vibration motor, the force calculation method of the HLVM is significantly different. In this study, a new force calculation method is used to analyze the electromagnetic–mechanical coupling of the HLVM. As a prototype, the novel design is small in size (−28.85%) but possesses similar acceleration. The experimental results verify the analysis results of the HLVM in the displacement and acceleration on a dummy jig. Full article
(This article belongs to the Section Control Systems)
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<p>Comparison between VLVM and HLVM.</p> Full article ">Figure 2
<p>HLVM prototype.</p> Full article ">Figure 3
<p>Force calculation of the HLVM: (<b>a</b>) magnetic circuit and magnetic flux direction; (<b>b</b>) parts of coil; (<b>c</b>) force direction on different parts of coil.</p> Full article ">Figure 3 Cont.
<p>Force calculation of the HLVM: (<b>a</b>) magnetic circuit and magnetic flux direction; (<b>b</b>) parts of coil; (<b>c</b>) force direction on different parts of coil.</p> Full article ">Figure 4
<p>Analysis method: (<b>a</b>) E–M coupling method; (<b>b</b>) acceleration calculation of the HLVM.</p> Full article ">Figure 5
<p>Prototype and new designs: (<b>a</b>) dimension and structure comparison and (<b>b</b>) the position of the type 2 coil.</p> Full article ">Figure 6
<p>Model and flux density distribution comparison.</p> Full article ">Figure 7
<p>Magnet length optimization.</p> Full article ">Figure 8
<p>Sample comparison and experimental setups: (<b>a</b>) prototype sample and final type sample; (<b>b</b>) parts of sample; (<b>c</b>) displacement measurement setup; and (<b>d</b>) acceleration measurement setup.</p> Full article ">Figure 8 Cont.
<p>Sample comparison and experimental setups: (<b>a</b>) prototype sample and final type sample; (<b>b</b>) parts of sample; (<b>c</b>) displacement measurement setup; and (<b>d</b>) acceleration measurement setup.</p> Full article ">Figure 9
<p>Displacement and acceleration comparison: (<b>a</b>) displacement results and (<b>b</b>) acceleration results.</p> Full article ">
20 pages, 6287 KiB  
Article
Experimental and Numerical Study on Incident Shock Wave/Boundary Layer Interaction Control
by Chuanbiao Zhang, Yanhao Luo, Hua Liang, Shanguang Guo and Hesen Yang
Actuators 2022, 11(6), 148; https://doi.org/10.3390/act11060148 - 2 Jun 2022
Cited by 2 | Viewed by 2280
Abstract
This study was designed to explore the control effect of pulsed arc discharge plasma actuation on the incident shock wave/boundary layer interaction (ISWBLI). Research was conducted on an ISWBLI flow field with 10 kHz single-channel pulsed arc discharge plasma actuation and pulsed arc [...] Read more.
This study was designed to explore the control effect of pulsed arc discharge plasma actuation on the incident shock wave/boundary layer interaction (ISWBLI). Research was conducted on an ISWBLI flow field with 10 kHz single-channel pulsed arc discharge plasma actuation and pulsed arc discharge plasma actuation array applied at Mach 2.0 experimentally and numerically. In the investigation, high-speed schlieren flow field visualization technology was adopted, focusing on the change in shock wave intensity caused by plasma actuation. Combined with the detached eddy simulation (DES) method, the numerical simulation focused on the regulating effect of plasma actuation on the separation zone. The key research results showed that, in terms of the spatial flow field, the simulation results were consistent with the experimental results. The single-channel actuation could only just achieve the control effect on the ISWBLI, while array actuation effectively weakened the shock wave intensity. Furthermore, the ISWBLI separation zone in the base flow field was crescent shaped. Its length at the middle of the flat plate was longer than that at the two sides. It was identified that, after applying single-channel actuation, the start of separation slightly moved forward. Similarly, after the application of array actuation, the start point of separation at the middle section in a spanwise direction moved forward by about 19 mm. The length of the separation zone increased by 30 mm but reduced at the two sides. Its influence, spanwise, was also significantly diminished. Full article
(This article belongs to the Special Issue Active Flow Control: Recent Advances in Fundamentals and Applications)
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<p>Schematic diagram of installation of experimental model in the wind tunnel.</p> Full article ">Figure 2
<p>Schematic diagram of experimental model. (<b>a</b>) plate model (<b>b</b>) The connection of the pulsed arc discharge plasma actuator array.</p> Full article ">Figure 3
<p>Schematic diagram of plasma actuation system and high-speed schlieren system.</p> Full article ">Figure 4
<p>Experimental schlieren results: (<b>a</b>,<b>c</b>,<b>e</b>) the base flow field; (<b>b</b>,<b>d</b>,<b>f</b>) the actuation flow field.</p> Full article ">Figure 5
<p>Computational model of ISWBLI: (<b>a</b>) 3D view; (<b>b</b>) front view; (<b>c</b>) top view.</p> Full article ">Figure 6
<p>Verification of mesh independence.</p> Full article ">Figure 7
<p>Model grid and boundary conditions.</p> Full article ">Figure 8
<p>Comparison of experimental schlieren and DES simulation calculation: (<b>a</b>) experimental schlieren; (<b>b</b>) numerical schlieren.</p> Full article ">Figure 9
<p>Plasma actuation evolution: (<b>a</b>) experimental schlieren; (<b>b</b>) numerical schlieren.</p> Full article ">Figure 10
<p>Density gradient contour of different cross sections: (<b>a</b>) <span class="html-italic">z</span> = 0; (<b>b</b>) <span class="html-italic">z</span> = 0.025 m; (<b>c</b>) <span class="html-italic">z</span> = 0.054 m.</p> Full article ">Figure 11
<p>Velocity contour of ISWBLI at <span class="html-italic">y</span> = 0 cross section.</p> Full article ">Figure 12
<p>Skin friction coefficient curve of base flow field at <span class="html-italic">z</span> = 0 cross section.</p> Full article ">Figure 13
<p>Skin friction coefficient curve of base flow field at different spanwise cross sections: (<b>a</b>) <span class="html-italic">z</span> = 0.025 m; (<b>b</b>) <span class="html-italic">z</span> = 0.054 m.</p> Full article ">Figure 14
<p>Pressure contour at <span class="html-italic">z</span> = 0 cross section at different moments.</p> Full article ">Figure 15
<p>Temperature contour at <span class="html-italic">z</span> = 0 cross section at different moments.</p> Full article ">Figure 16
<p>Numerical schlieren of three cross sections: (<b>a</b>) <span class="html-italic">z</span> = 0 base flow field; (<b>b</b>) <span class="html-italic">z</span> = 0 actuation flow field; (<b>c</b>) <span class="html-italic">z</span> = 0.025 m base flow field; (<b>d</b>) <span class="html-italic">z</span> = 0.025 m actuation flow field; (<b>e</b>) <span class="html-italic">z</span> = 0.054 m base flow field; (<b>f</b>) <span class="html-italic">z</span> = 0.054 m actuation field.</p> Full article ">Figure 17
<p>Skin friction coefficient curve at different spanwise cross sections: (<b>a</b>) <span class="html-italic">z</span> = 0; (<b>b</b>) <span class="html-italic">z</span> = 0.025 m; (<b>c</b>) <span class="html-italic">z</span> = 0.054 m.</p> Full article ">Figure 18
<p>The form of separation zone at <span class="html-italic">y</span> = 0 cross section: (<b>a</b>) base flow field; (<b>b</b>) actuation flow field.</p> Full article ">Figure 19
<p>The schematic diagram of array actuation model.</p> Full article ">Figure 20
<p>Numerical schlieren at <span class="html-italic">z</span> = 0 cross section: (<b>a</b>) 10 kHz actuation flow field; (<b>b</b>) base flow field.</p> Full article ">Figure 21
<p>Numerical schlieren of two cross sections: (<b>a</b>) <span class="html-italic">z</span> = 0.025 m base flow field; (<b>b</b>) <span class="html-italic">z</span> = 0.025 m actuation flow field; (<b>c</b>) <span class="html-italic">z</span> = 0.054 m base flow field; (<b>d</b>) <span class="html-italic">z</span> = 0.054 m actuation field.</p> Full article ">Figure 22
<p>Velocity contour of ISWBLI <span class="html-italic">y</span> = 0 cross section: (<b>a</b>) base flow field; (<b>b</b>) actuation flow field.</p> Full article ">Figure 23
<p>Skin friction coefficient curve at <span class="html-italic">z</span> = 0 cross section.</p> Full article ">Figure 24
<p>Skin friction coefficient curve at different spanwise cross sections: (<b>a</b>) <span class="html-italic">z</span> = 0.025 m; (<b>b</b>) <span class="html-italic">z</span> = 0.054 m.</p> Full article ">
18 pages, 9014 KiB  
Article
Development of a Novel Dual Servo Magnetic Levitation Stage
by Dahoon Ahn, Ji-Won Jin, Hyeeun Yun and Jaeheon Jeong
Actuators 2022, 11(6), 147; https://doi.org/10.3390/act11060147 - 30 May 2022
Cited by 7 | Viewed by 3368
Abstract
The main objective of this paper is to propose, design, and control a novel dual servo magnetic levitation stage which is precise and vacuum compatible. The dual servo mechanism, comprising a coarse stage and a fine stage, was applied to a magnetic levitation [...] Read more.
The main objective of this paper is to propose, design, and control a novel dual servo magnetic levitation stage which is precise and vacuum compatible. The dual servo mechanism, comprising a coarse stage and a fine stage, was applied to a magnetic levitation stage system for the first time. The dual servo stage achieves high precision and a long stroke at the same time. The fine stage, which comprises voice coil motors, achieves high-precision motion by overcoming the limit of the coarse stage, the form of which is a planar motor. The planar motor was mathematically modeled and analyzed with respect to the main design parameters, after which the fine stage was optimally designed to be driven by high force. Both stages including a common heat exchanger were manufactured, and the heat exchanger cools down the heat given off from the planar motor and voice coil motors. The position measuring system consisted of laser interferometers and capacitive sensors, and the integrated dual servo stage was controlled with a master–slave control scheme. The experimental results showed a precision of 10 nm, thus confirming the suitability of the developed magnetic levitation stage for a high-precision fabrication process such as wafer lithography. Full article
(This article belongs to the Special Issue Actuating, Sensing, Control, and Instrumentation for Ultra Precision Engineering)
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<p>Schematic diagram showing the structure of the dual servo maglev stage.</p> Full article ">Figure 2
<p>Design of the fine stage: (<b>a</b>) The topology of the VCMs; (<b>b</b>) the fine stage stator with coils; and (<b>c</b>) the fine stage mover with magnets (inverted) [<a href="#B27-actuators-11-00147" class="html-bibr">27</a>]. Reprinted from International Journal of Applied Electromagnetics and Mechanics, 62, Dahoon Ahn, et al., Design process of square column-shaped voice coil motor design for magnetic levitation stage, 517–540, Copyright (2020), with permission from IOS Press.</p> Full article ">Figure 3
<p>Design of the coarse stage: (<b>a</b>) The topology of the 3-phase coils; (<b>b</b>) the coarse stage stator with a two-dimensional magnet array.</p> Full article ">Figure 4
<p>Design parameters of the planar motor, (<b>a</b>) magnet array, (<b>b</b>) coil array, and (<b>c</b>) four sets of 3-phase coils.</p> Full article ">Figure 5
<p>Results of the sensitivity analysis. (<b>a</b>) effect of height of the magnet array; (<b>b</b>) effect of the Halbach magnet ratio; (<b>c</b>) effect of bundle width of the coil; (<b>d</b>) effect of height of the coil array; (<b>e</b>) effect of electric current of the coil; (<b>f</b>) effect of height of the coil array.</p> Full article ">Figure 6
<p>FE analysis results of the water-cooling heat exchanger: (<b>a</b>) configuration of the heat exchanger; (<b>b</b>) coolant channel engraved on the stator of the fine stage (<b>c</b>) temperature at the coils; (<b>d</b>) temperature at the aluminum block (the stator of the fine stage); (<b>e</b>) temperature at the ceramic block (the stator of the coarse stage) (<b>f</b>) temperature at the coolant.</p> Full article ">Figure 7
<p>Arrangement of the motion feedback sensors: (<b>a</b>) global sensors for the fine stage, (<b>b</b>) local sensors for the coarse stage.</p> Full article ">Figure 8
<p>The realized dual servo maglev stage system.</p> Full article ">Figure 9
<p>Control block diagram of the master–slave control scheme of the dual servo maglev stage.</p> Full article ">Figure 10
<p>The evaluated motion stroke data of the dual servo stage: (<b>a</b>) <span class="html-italic">x</span> direction, (<b>b</b>) <span class="html-italic">y</span> direction.</p> Full article ">Figure 11
<p>The evaluated in-position stability data of the dual servo stage: (<b>a</b>) <span class="html-italic">x</span> direction, (<b>b</b>) <span class="html-italic">y</span> direction, (<b>c</b>) <span class="html-italic">z</span> direction, (<b>d</b>) θ<span class="html-italic"><sub>x</sub></span> direction, (<b>e</b>) θ<span class="html-italic"><sub>y</sub></span> direction, (<b>f</b>) θ<span class="html-italic"><sub>z</sub></span> direction.</p> Full article ">Figure 12
<p>The evaluated minimum positioning resolution data of the dual servo stage: (<b>a</b>) <span class="html-italic">x</span> direction, (<b>b</b>) <span class="html-italic">y</span> direction, (<b>c</b>) <span class="html-italic">z</span> direction, (<b>d</b>) θ<span class="html-italic"><sub>x</sub></span> direction, (<b>e</b>) θ<span class="html-italic"><sub>y</sub></span> direction, (<b>f</b>) θ<span class="html-italic"><sub>z</sub></span> direction.</p> Full article ">Figure 13
<p>The evaluated settling time data of the dual servo stage: (<b>a</b>) <span class="html-italic">x</span> direction, (<b>b</b>) <span class="html-italic">y</span> direction.</p> Full article ">Figure 14
<p>The current provided to the coils when the dual servo maglev stage moves 50 mm along the <span class="html-italic">x</span>-axis and <span class="html-italic">y</span>-axis: (<b>a</b>) measured position along <span class="html-italic">x</span> direction, (<b>b</b>) measured position along <span class="html-italic">y</span> direction, (<b>c</b>) electric current applied to the coils placed along the y-axis, (<b>d</b>) electric current applied to the coils placed along the <span class="html-italic">x</span>-axis, (<b>e</b>) electric current applied to the HVCMs, (<b>f</b>) electric current applied to the VVCMs.</p> Full article ">
17 pages, 4377 KiB  
Article
Fusion Localization Algorithm Based on Robust IMM Model Combined with Semi-Definite Programming
by Yan Wang, Yang Cheng and Long Cheng
Actuators 2022, 11(6), 146; https://doi.org/10.3390/act11060146 - 29 May 2022
Cited by 2 | Viewed by 1866
Abstract
With the continuous development of wireless sensor network (WSN) technology, WSN has gradually become one of the key technologies of the Internet, and is widely used in indoor target location technology. However, the obstacles will have a great influence on the distance measurement, [...] Read more.
With the continuous development of wireless sensor network (WSN) technology, WSN has gradually become one of the key technologies of the Internet, and is widely used in indoor target location technology. However, the obstacles will have a great influence on the distance measurement, and it will result in a large positioning error. Therefore, how to deal with the non-line-of-sight (NLOS) error becomes an important problem. In this paper, Interacting Multiple Model (IMM) was used to identify NOLS/LOS. The NLOS probability was calculated by Markov transform probability, and the likelihood function was calculated by extended Kalman filter (EKF). The NLOS probability was compared with the LOS probability to judge whether the measurement contained the NLOS error. A robust algorithm combining IMM model with semidefinite programming (IMM-SDP) was proposed. The improved convex programming algorithm was proposed to reduce the NLOS error. Simulation and experimental results showed that the proposed algorithm can effectively reduce the influence of NLOS error and achieve higher positioning accuracy compared with the existing positioning methods. Full article
(This article belongs to the Special Issue Wireless Sensor–Actuator Networks)
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<p>The flow chart of the proposed algorithm.</p> Full article ">Figure 2
<p>Markov transformation process.</p> Full article ">Figure 3
<p>The trajectory of a mobile node.</p> Full article ">Figure 4
<p>RMSE versus the mean value of NLOS errors.</p> Full article ">Figure 5
<p>RMSE versus the standard deviation of NLOS errors.</p> Full article ">Figure 6
<p>RMSE versus the different probability of NLOS errors.</p> Full article ">Figure 7
<p>RMSE versus the different probability of LOS errors.</p> Full article ">Figure 8
<p>NLOS exponential distribution parameter.</p> Full article ">Figure 9
<p>NLOS uniform distribution parameters.</p> Full article ">Figure 10
<p>The ultra-wideband (UWB) node is connected with the power supply.</p> Full article ">Figure 11
<p>The experimental scene.</p> Full article ">Figure 12
<p>The localization error at each sampling point.</p> Full article ">
14 pages, 5539 KiB  
Article
Research on Control Strategy of Heavy-Haul Train on Long and Steep Downgrades
by Huazhen Yu, Guoxuan Tai, Zhengnan Lin and Youneng Huang
Actuators 2022, 11(6), 145; https://doi.org/10.3390/act11060145 - 28 May 2022
Viewed by 2139
Abstract
The control of heavy-haul trains has always been the focus of China’s railway transportation development. One key challenge is the coordination of electric braking and air braking control when the electric-air combined braking is applied on long and steep downgrades. This is normally [...] Read more.
The control of heavy-haul trains has always been the focus of China’s railway transportation development. One key challenge is the coordination of electric braking and air braking control when the electric-air combined braking is applied on long and steep downgrades. This is normally reliant on manual driving and thus is not cost-effective. To improve the safety and efficiency of train operation in existing heavy-haul railway lines, a multi-label random forest (ML-RF) based approach for heavy-haul train (HHT) operation is proposed. The control characteristics of electric braking and air braking on long and steep downgrades are analyzed first. A prediction model of control strategy is then established with the combination of line conditions and definition of multi-label learning. To evaluate the performance of the model, the 10-fold cross-validation method is adopted. Furthermore, a model parameter optimization algorithm based on evaluation metrics is designed. The feasibility of the proposed approach is demonstrated by the testing results on the actual train running data of one railway line. Full article
(This article belongs to the Section Actuators for Land Transport)
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<p>Long and steep downgrades.</p> Full article ">Figure 2
<p>Prediction of control strategy.</p> Full article ">Figure 3
<p>Implementation of ML-RF.</p> Full article ">Figure 4
<p>Schematic diagram of one random forest.</p> Full article ">Figure 5
<p>Evaluation results of ML-RF with different number of trees in the forest (<span class="html-italic">n</span><sub>tree</sub>). (<b>a</b>) Accuracy Score; (<b>b</b>) Jaccard Similarity; (<b>c</b>) F1 Score; (<b>d</b>) Hamming Loss.</p> Full article ">Figure 6
<p>Evaluation results of ML-RF with different number of features selected as candidates at each split (<span class="html-italic">n</span><sub>fea</sub>). (<b>a</b>) Accuracy Score; (<b>b</b>) Jaccard Similarity; (<b>c</b>) F1 Score; (<b>d</b>) Hamming Loss.</p> Full article ">Figure 7
<p>Evaluation results of ML-RF with different maximum depth of tree (<span class="html-italic">m</span><sub>dep</sub>). (<b>a</b>) Accuracy Score; (<b>b</b>) Jaccard Similarity; (<b>c</b>) F1 Score; (<b>d</b>) Hamming Loss.</p> Full article ">Figure 8
<p>Scenario 1: comparison of predicted and actual control strategy. (<b>a</b>) Section from 19.3 km to 25 km.</p> Full article ">Figure 9
<p>Scenario 2: comparison of predicted and actual control strategy. (<b>a</b>) Section from 14 km to 20.5 km. (<b>b</b>) Section from 38 km to 44 km.</p> Full article ">Figure 10
<p>Scenario 1: train operation curve under predicted control strategy.</p> Full article ">Figure 11
<p>Scenario 2: train operation curve under predicted control strategy.</p> Full article ">
16 pages, 1239 KiB  
Article
Simultaneous Identification of Free and Supported Frequency Response Functions of a Rotor in Active Magnetic Bearings
by Michael Kreutz, Johannes Maierhofer, Thomas Thümmel and Daniel J. Rixen
Actuators 2022, 11(6), 144; https://doi.org/10.3390/act11060144 - 28 May 2022
Cited by 2 | Viewed by 2130
Abstract
Frequency response functions (FRFs) of rotor systems can be used as indicator functions for condition monitoring. Component-wise FRFs are of high interest to locate errors in the case of defects. To enable continuous monitoring, measurements should be taken during operation. This contribution shows [...] Read more.
Frequency response functions (FRFs) of rotor systems can be used as indicator functions for condition monitoring. Component-wise FRFs are of high interest to locate errors in the case of defects. To enable continuous monitoring, measurements should be taken during operation. This contribution shows methods of using active magnetic bearings (AMBs) for simultaneously determining different FRFs of a rotor system. The AMBs, in addition to supporting the rotor, are used simultaneously as sensors and actuators. Two different types of FRFs, namely, the one associated with the free rotor and with the supported rotor can be determined from a single experiment. This procedure does not need any change in the assembly because the AMBs are simultaneously used as bearing and excitation device. Considering as excitation the total bearing force of the AMBs results in the FRF of the free rotor. The FRF of the supported system is determined by considering a perturbation force only, which is applied on top of the controlled AMB force. As a showcase, an academic rotor test rig is used with and without rotation to verify the applicability of the method. To evaluate and interpret the results of the experiments, a numerical model of the rotor using finite-element formulations is used. Full article
(This article belongs to the Special Issue Selected Papers from the 17th International Symposium on Magnetic Bearings (ISMB17))
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<p>Schematic view of the magnetic bearing test rig, see also [<a href="#B19-actuators-11-00144" class="html-bibr">19</a>].</p> Full article ">Figure 2
<p>Photo of the magnetic bearing test rig with piezo force platforms.</p> Full article ">Figure 3
<p>Control scheme including additional excitation.</p> Full article ">Figure 4
<p>Parametrization of the simulation model by comparison with FRF-results for impact testing with different system setups. The eigenfrequencies of the supported system without the cardanic joint (<b>b</b>) are marked by dashed lines to highlight the difference between the system without (<b>b</b>) and with (<b>c</b>) the cardanic joint.</p> Full article ">Figure 5
<p>Model of the supported identified system using <math display="inline"><semantics> <msub> <mi mathvariant="bold-italic">F</mi> <mi>exci</mi> </msub> </semantics></math> as input signal.</p> Full article ">Figure 6
<p>FRF <math display="inline"><semantics> <msub> <mi>H</mi> <mi>supp</mi> </msub> </semantics></math> of the rotor supported in magnetic bearings (using only excitation force), non-rotating.</p> Full article ">Figure 7
<p>Model of the identified free system using the total force <math display="inline"><semantics> <msub> <mi mathvariant="bold-italic">F</mi> <mi>total</mi> </msub> </semantics></math> as input signal.</p> Full article ">Figure 8
<p>FRF <math display="inline"><semantics> <msub> <mi>H</mi> <mi>free</mi> </msub> </semantics></math> of the free rotor (using the total force), non-rotating, with coherence.</p> Full article ">Figure 9
<p>Ordinary coherence between the two input signals (total force).</p> Full article ">Figure 10
<p>FRF amplitude <math display="inline"><semantics> <mrow> <mrow> <mo>|</mo> </mrow> <msub> <mi>H</mi> <mi>free</mi> </msub> <mrow> <mo>|</mo> </mrow> </mrow> </semantics></math> of the free rotor (using total force) for <math display="inline"><semantics> <mrow> <mn>800</mn> <mspace width="0.166667em"/> <mi>rpm</mi> </mrow> </semantics></math>.</p> Full article ">Figure 11
<p>Comparison of the experimentally determined FRFs for non-rotating and rotating system. The results for the supported system are obtained by considering the estimated excitation force. The results for the free rotor, shown here, use the measured total force.</p> Full article ">Figure 12
<p>Decoupling procedure to obtain the dynamics of the bearings.</p> Full article ">Figure 13
<p>Decoupled <math display="inline"><semantics> <msub> <mi mathvariant="italic">Z</mi> <mi>AMB</mi> </msub> </semantics></math> for <math display="inline"><semantics> <mrow> <mn>800</mn> <mspace width="0.166667em"/> <mi>rpm</mi> </mrow> </semantics></math>, split in real and imaginary parts.</p> Full article ">
15 pages, 2639 KiB  
Article
Research on Takagi-Sugeno Fuzzy-Model-Based Vehicle Stability Control for Autonomous Vehicles
by Zeyu Jiao, Jian Wu, Zhengfeng Chen, Fengbo Wang, Lijun Li, Qingfeng Kong and Fen Lin
Actuators 2022, 11(6), 143; https://doi.org/10.3390/act11060143 - 26 May 2022
Cited by 2 | Viewed by 2392
Abstract
Human–machine cooperative driving is an important stage in the development of autonomous driving technology. However, in emergencies, the problem of vehicle stability control for human–computer cooperative autonomous vehicles is still worthy of attention. This paper mainly realizes the stability control of the human–machine [...] Read more.
Human–machine cooperative driving is an important stage in the development of autonomous driving technology. However, in emergencies, the problem of vehicle stability control for human–computer cooperative autonomous vehicles is still worthy of attention. This paper mainly realizes the stability control of the human–machine cooperative driving vehicle through active steering and considers the influence of the change of vehicle speed on the vehicle stability control performance. Therefore, a vehicle stability control method based on the superposition of steering torque is proposed, in which the Takagi-Sugeno fuzzy model is used to solve the variable parameter problem. Firstly, a vehicle system model with steering moment as input is established to ensure that the driver can participate in the steering control. Secondly, the nonlinear T-S fuzzy model is established by fuzzifying the local linear model. Then, the parallel-distributed-compensation (PDC) method is used to design the vehicle stability controller, and the asymptotic stability of the system in the range of variable parameters is proved by using the Lyapunov stability principle. Finally, the simulation and experimental results show that the control method can improve the handling stability of the human–machine cooperative driving vehicle under the condition of vehicle speed variation. Full article
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<p>Schematic diagram of the steering system.</p> Full article ">Figure 2
<p>DOF vehicle dynamics model.</p> Full article ">Figure 3
<p>Degree of membership.</p> Full article ">Figure 4
<p>(<b>a</b>) Speed (km/h), (<b>b</b>) lateral displacement (m), (<b>c</b>) deviation (m), (<b>d</b>) steering torque control input (Nm), (<b>e</b>) steering angle (°), and (<b>f</b>) yaw rate (°/s).</p> Full article ">Figure 5
<p>(<b>a</b>) Speed (km/h), (<b>b</b>) lateral displacement (m), (<b>c</b>) deviation (m), (<b>d</b>) steering torque control input (Nm), (<b>e</b>) steering angle (°), and (<b>f</b>) yaw rate (°/s).</p> Full article ">Figure 6
<p>Semi-experimental scheme diagram of active steering.</p> Full article ">Figure 7
<p>(<b>a</b>) Speed (km/h), (<b>b</b>) lateral displacement (m), (<b>c</b>) deviation (m), (<b>d</b>) steering torque control input (Nm), (<b>e</b>) steering angle (°), (<b>f</b>) yaw rate (°/s), and (<b>g</b>) motor current (A).</p> Full article ">Figure 8
<p>(<b>a</b>) Speed (km/h), (<b>b</b>) lateral displacement (m), (<b>c</b>) deviation (m), (<b>d</b>) steering torque control input (Nm), (<b>e</b>) steering angle (°), (<b>f</b>) yaw rate (°/s), and (<b>g</b>) motor current (A).</p> Full article ">
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