Automation Technology

A three-fingered gripper with flexure hinges actuated by shape memory alloy (SMA) wires was designed and prototyped. The aim of the work was the manipulation of small, almost cylindrical objects, e.g. test tubes, by a device having small overall dimensions. A parametric study of four different, but similar, fingers was conducted with the aim of obtaining a solution with a good amplification ratio and a gripping force almost constant during closure. The use of flexure hinges simplifies the design, but limits the finger range of motion. Moreover, it was possible to find a configuration with sufficient work space. Once the finger geometry was defined, the whole hand was then designed with the aim of producing a compact hand contained in a cylindrical volume (φ 65×h 65 mm), and the first prototype was built. Preliminary tests demonstrated its good dimensioning and the success of some technological solutions. The experimental transmission ratio was almost the same as the theoretical one....

Fast Tool Servo (FTS) diamond turning is a promising machining process for fabricating high precision micro-structured surfaces. However, the dynamics of FTS affects its performance and causes form error in the machined surfaces, thus shortening the useful bandwidth of the FTS for precision machining. In this paper, an Integral Sliding Mode Control (ISMC) algorithm is proposed to control the FTS in order to achieve the desired closed-loop dynamics. The robustness of the ISMC to disturbance and model uncertainties or variations is ensured by the implementation of disturbance estimation and an integral switching control action. The influence of the FTS dynamics can thereby be minimized by modifying the tool path offline with the inverse of the desired dynamics. Experiments on machining of typical micro-structured surfaces show that the proposed method is effective in reducing the FTS dynamics induced form error in the machined surface.

A supply chain (SC) is an organization in which multiple companies cooperate in supply functions, e.g., moving information or materials. Previous studies of SC designing and planning are categorized by their planning time periods into three categories, e.g., strategic, tactical, and operational. Top-down design of an SC, where design decisions are made in the sequence of strategic, tactical, and operational, is rational because of preventing rework of design work. But as few models supports strategic decision making quantitatively, top-down design of an SC has not been realized. In the present study, a method of quantitatively expressing SC’s capabilities of flowing information and materials and simulating its performance is developed. The method is then implemented with a system dynamic model to evaluate, qualitatively and quantitatively, the effectiveness of the model.

In this paper, a novel stair-climbing wheelchair is proposed. This new architecture represents an improvement over previous designs, in particular with regards to stability and safety during stair-climbing operations. The proposed mechanical architecture is hybrid: two locomotion units based on a “rotating leg” system are coupled with an idle track. This structure satisfies many design requirements: small dimensions, reduced weight, and a stable and regular climbing trajectory. In particular, the focus of this study is the design of an actuation system, the choice of suitable control logics, and the dynamic analysis of the proposed solution. The behavior of the wheelchair was tested through multibody simulation. The simulation results show that the proposed device can climb a staircase in a stable and safe manner. Certain smart dynamic features of the wheelchair were also proven. In particular, the efficacy of the cooperative actuation system and the effectiveness of the proposed co...

Mantis 2 is a small-scale leg-wheel ground mobile robot, designed for exploration, surveillance and inspection tasks in unstructured environments. It is equipped with two actuated front wheels, two passive rear wheels, and two rotating legs with praying Mantis profile, specially conceived for step and obstacle climbing. Locomotion is purely wheeled on regular surfaces, with high energetic efficiency and maneuverability, and with stable camera vision. In case of obstacles or terrain irregularities, the rotating legs increase the motion capability. The main innovation of the second version is the introduction of passive one-way auxiliary wheels on each leg, which improve the efficacy of step climbing. The paper discusses analytical and experimental results on step ascent and descent and locomotion on irregular surfaces.

In the last decade, the underwater activities performed by archaeologists and biologists have benefited from scientific research on the guidance, control, and sensory systems of unmanned vehicles. In fact, because underwater sites of interest are often difficult for divers to access, the use of unmanned vehicle technology to conduct surveys could be quite advantageous. In this paper, a novel and partially-biomimetic underwater robot, referred to as BRAVe (Biomimetic Research Autonomous Vehicle), is presented. For documentation purposes, it is equipped with a hybrid propulsion system, which consists of two different types of thrusters. The thrusters are designed to compensate for their reciprocal flaws in order to achieve a more efficient overall system. Specifically, the biomimetic thruster is employed for its superior energetic efficiency, and the horizontal propellers are exploited for accurate maneuvering. While the documentation and 3D reconstruction of the underwater seabed is ...

This study aims to determine effective methods for improving the energy efficiency of a water hydraulic Fluid Switching Transmission (FST). This paper introduces three methods to reduce energy consumption: lowering the velocity of the electric motor and stopping the motor during the working and deceleration phases, respectively (first method); restricting the working pressure within a certain range by using an unload valve (second method) or using the idling stop method (third method). Next these three methods are analyzed and compared. Experimental results show that by using the proposed methods, the energy and net energy consumption are greatly reduced. The greatest reductions are from 71.5 to 78.3% for energy consumption and from 65.1 to 66.2% for net energy consumption, corresponding to variations in the reference velocity from 600 to 1000 min-1. Additionally, the steady state errors in the proposed methods are slightly decreased in the working phase while the transient response...

In this study, the tool performance of two types of binderless diamond tools – single-crystal diamond (SCD) and nano-polycrystalline diamond (NPD) – is investigated in the high-speed cutting of titanium alloy (Ti-6Al-4V) with a water-soluble coolant. The NPD tool allows for a larger cutting force than the SCD tool by dulling of the cutting edge, despite NPD being harder than SCD. This large cutting force and the very low thermal conductivity of NPD yield a high cutting temperature above 500°C, which promotes the adhesion of the workpiece to the tool face, thereby increasing tool wear. Based on the morphology of the tool edge without scratch marks and the elemental analysis by energy-dispersive X-ray spectroscopy (EDX) of both the flank face and the cutting chips, diffusion-dissolution wear is determined to be the dominant mechanism in the diamond tool. A thin TiC layer seems to be formed in the boundary between the diamond tool and the titanium alloy at high temperatures; this is re...

In the last decade, the underwater activities performed by archaeologists and biologists have benefited from scientific research on the guidance, control, and sensory systems of unmanned vehicles. In fact, because underwater sites of interest are often difficult for divers to access, the use of unmanned vehicle technology to conduct surveys could be quite advantageous. In this paper, a novel and partially-biomimetic underwater robot, referred to as BRAVe (Biomimetic Research Autonomous Vehicle), is presented. For documentation purposes, it is equipped with a hybrid propulsion system, which consists of two different types of thrusters. The thrusters are designed to compensate for their reciprocal flaws in order to achieve a more efficient overall system. Specifically, the biomimetic thruster is employed for its superior energetic efficiency, and the horizontal propellers are exploited for accurate maneuvering. While the documentation and 3D reconstruction of the underwater seabed is ...

ABSTRACT In this paper, a novel magnetic actuator named Linear Magnetic Actuator (LMA) is proposed, designed and fabricated for applications such as active magnetic bearing systems to deal with vibration problems in rotating machines. The LMA actuator is constructed from a moving body called ‘mover’ and three driving parts which drive the mover. Real-time experiments on the LMA have been conducted to derive a mathematical model for this actuator to investigate the generated electro-magnetic force as well as further research. The modeling results in a comparison with the actual performance show that the electro-magnetic force varied symmetrically with the mover motion defined by the applied current. Furthermore, an advanced trajectory controller — online tuning fuzzy PID controller has been designed for the LMA in order to improve the working performance. Finally, real-time experiments have been carried out to investigate the tracking performance of the designed LMA control system. The experimental results prove that the LMA driven by the proposed controller could track the desired trajectories with high accuracy.