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This paper describes the third year of a studyat the University of Manitoba aimed at exploring how theCanadian Engineering Accreditation Board (CEAB)graduate attributes are manifested and measured in theFaculty of Engineering’s... more
This paper describes the third year of a studyat the University of Manitoba aimed at exploring how theCanadian Engineering Accreditation Board (CEAB)graduate attributes are manifested and measured in theFaculty of Engineering’s curriculum. Instructors from theDepartments of Biosystems, Civil, Electrical andComputer, and Mechanical Engineering were asked toconsider the presence of four attributes and theirsubsequent indicators in one engineering course taught inthe 2013-14 academic year. The attributes were: AKnowledge Base for Engineering, Individual and TeamWork, Impact of Engineering on Society and theEnvironment, and Economics and Project Management.Data were gathered using a self-administered checklist,which was introduced to instructors in a workshopsetting. The checklist has evolved over the three years inan effort to define student attribute competency levels andto create an assessment tool that meets the needs of boththe researchers and the instructors, as we work togetherto...
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This paper describes the findings from athree-year longitudinal study at the University ofManitoba designed to explore how the CanadianEngineering Accreditation Board (CEAB) graduateattributes are manifested and measured in the Faculty... more
This paper describes the findings from athree-year longitudinal study at the University ofManitoba designed to explore how the CanadianEngineering Accreditation Board (CEAB) graduateattributes are manifested and measured in the Faculty ofEngineering’s curriculum. Instructors from theDepartments of Biosystems, Civil, Mechanical, andElectrical and Computer Engineering were asked toconsider the presence of four of the 12 CEAB attributesand their subsequent indicators in one engineering coursetaught in one academic year. Each year, four differentattributes were targeted, chosen to reflect both thetraditional/technical and the professional/workplacecompetencies. Data were collected using a selfadministeredchecklist, which evolved over the three yearsof the study in an effort to more clearly define studentattribute competency levels, and to develop a commonlanguage and understanding in regards to the graduateattributes and the process of outcomes-based assessment.This final phase of the s...
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Publisher Summary This chapter explores fuzzy control system techniques and their application in hydraulically actuated industrial robots. Fuzzy control is based on fuzzy logic that is close in spirit to human thinking and natural... more
Publisher Summary This chapter explores fuzzy control system techniques and their application in hydraulically actuated industrial robots. Fuzzy control is based on fuzzy logic that is close in spirit to human thinking and natural language. It can provide robust control and accuracy and is ideally suited for systems with complex models. The chapter deals with the problem of position control of hydraulically actuated robots. Hydraulic robots have different control requirements. The chapter discusses the design of a suitable fuzzy controller in which the inputs are position and velocity errors. The universe of discourse of position and velocity errors was partitioned into five and three simple sets, respectively. The controller performed well but did not eliminate the steady-state error. This was because of the unavoidable nonlinearities. A novel scheme, called “fuzzy reset compensation,” was then employed in parallel with this controller. The compensator used velocity error to boost the control signal obtained from the fuzzy controller. The fuzzy controller was successfully applied to control various links of an instrumented Unimate MK-II hydraulic robot.
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SUMMARYA fundamental study on the control of hydraulically actuated robots is presented. Dynamic modelling is performed in both time-domain and frequency-domain. It is shown that the inclusion of hydraulic elements increases the order of... more
SUMMARYA fundamental study on the control of hydraulically actuated robots is presented. Dynamic modelling is performed in both time-domain and frequency-domain. It is shown that the inclusion of hydraulic elements increases the order of the system. Hydraulic compliance is the most effective factor in this regard.Three distinct control strategies are applied. Their performances are evaluated and compared. All three methods are exemplified with a two link hydraulic robot in a computer simulation. The robot has the same hydraulic configuration as many existing industrial manipulators. The simulation program is written in ACSL (Advanced Continuous Simulation Language) running on a VAX 11/750.
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This paper addresses the control problem for a class of heavy-duty hydraulic machines in order to achieve coordinated motion control of the implement. A model and sensor-based control algorithm is proposed which is applied in conjunction... more
This paper addresses the control problem for a class of heavy-duty hydraulic machines in order to achieve coordinated motion control of the implement. A model and sensor-based control algorithm is proposed which is applied in conjunction with closed-loop components. The algorithm is basically a feedforward load compensating scheme which uses the measured hydraulic line pressures along with the appropriate portion of the hydraulic model to control the joint velocities. The effects of nonlinear dynamic coupling between the links, loading, coupled actuation and power limitations are compensated in this technique. The closed-loop part consists of PD components. A knowledge of some hydraulic parameters is the only requirement of this control scheme. The proposed approach has been examined through simulation and is supported by experimental evidence. The experiments were performed on a Caterpillar 215B excavator. The control program is written in the C language, running on a computer syst...
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This paper presents the construction of a low-cost data acquisition system (DAS) prototype based on Raspberry Pi-2 microcomputer. The prototype is designed to operate as a standalone system without the need for an additional personal... more
This paper presents the construction of a low-cost data acquisition system (DAS) prototype based on Raspberry Pi-2 microcomputer. The prototype is designed to operate as a standalone system without the need for an additional personal computer (PC). It performs the data acquisition, online plotting and data logging, simultaneously. This is a general-purpose setup, as it is capable of reading any analog sensor giving output in the designed range, or through appropriate signal conditioning. The system is tested in a Mechanical laboratory by collecting data which are compared to a benchmark DAS. Statistical analyses are also performed on the acquired data. It is proved that both signals are identical with only minor differences.
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In this paper, a control scheme is developed and evaluated for stable bilateral haptic teleoperation of a single-rod hydraulic actuator subjected to base disturbance. The proposed controller, based on Lyapunov stability technique, is... more
In this paper, a control scheme is developed and evaluated for stable bilateral haptic teleoperation of a single-rod hydraulic actuator subjected to base disturbance. The proposed controller, based on Lyapunov stability technique, is capable of reducing position errors at master and slave sides, and provides a feel of the contact force between the actuator and the task environment to the operator without a need for direct measurement. The controller requires only the measurements of the actuator line pressures and displacements of the master and slave. The system stability is insensitive to the uncertainties of the physical parameters and of the measurement of the base point motion. Stability of the proposed controller incorporating hydraulic nonlinearities and operator dynamics with an estimated upper value for the base disturbance is analytically proven. Simulation studies validate that the proposed control system is stable while interacting with a task environment. Experimental results demonstrate the effectiveness of control scheme in maintaining stability, while having good position tracking by the hydraulic actuator as well as providing a haptic feel to the operator without direct measurement of interaction force, while the hydraulic actuator is subjected to base disturbance.
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SUMMARYOdometry errors, which occur during wheeled mobile robot movement, are inevitable as they originate from hard-to-avoid imperfections such as unequal wheels diameters, joints misalignment, backlash, slippage in encoder pulses, and... more
SUMMARYOdometry errors, which occur during wheeled mobile robot movement, are inevitable as they originate from hard-to-avoid imperfections such as unequal wheels diameters, joints misalignment, backlash, slippage in encoder pulses, and much more. This paper extends the method, developed previously by the authors for calibration of differential mobile robots, to reduce positioning errors for the class of mobile robots having omnidirectional wheels. The method is built upon the easy to construct kinematic formulation of omnidirectional wheels, and is capable of compensating both systematic and non-systematic errors. The effectiveness of the method is experimentally investigated on a prototype three-wheeled omnidirectional mobile robot. The validations include tracking unseen trajectories, self-rotation, as well as travelling over surface irregularities. Results show that the method is very effective in improving position errors by at least 68%. Since the method is simple to implement and has no assumption on the sources of errors, it should be considered seriously as a tool for calibrating omnidirectional mobile having any number of wheels.
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One of the main faults that may happen in electrohydrostatic systems is the actuator internal leakage that occurs due to wearing in the piston seal. This paper focuses on detecting the internal leakage using multiscale analysis of... more
One of the main faults that may happen in electrohydrostatic systems is the actuator internal leakage that occurs due to wearing in the piston seal. This paper focuses on detecting the internal leakage using multiscale analysis of experimental data measured from an electrohydrostatic actuator (EHA) test rig. Multiscale techniques are the strong tools in analysis of time series, as they are able to extract more useful information about dynamical systems as compared with single-scale methods. In this paper, several multiscale measures are obtained from the actuator pressure signal of an EHA testbed in both healthy and faulty operating modes. The measures are correlation fractal dimension, variance fractal dimension, maximal Lyapunov exponent, average value of correlation entropy, and wavelet detailed and approximation coefficients. Sensitivity of each measure to the effect of the internal leakage is quantified by calculating the percentage of change of faulty measures with respect to those of the healthy operating mode. The percentage of change in the mean value of correlation entropy and level five wavelet detailed coefficient indicated that these two measures are appropriate indicators to detect different levels of actuator internal leakage in EHA systems. In contrast, the correlation fractal dimension, the variance fractal dimension, and maximal Lyapunov exponent did not exhibit reliable sensitivities to the internal leakage.
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This paper investigates haptic-enabled teleoperation of a base-excited hydraulic manipulator working under a wireless communication channel. The intended application is live power line maintenance. With respect to this application, three... more
This paper investigates haptic-enabled teleoperation of a base-excited hydraulic manipulator working under a wireless communication channel. The intended application is live power line maintenance. With respect to this application, three main challenges are recognized in the field: need for the force feedback, wireless communication between master and slave sites, and base excitation of the slave manipulator. In this paper, a test rig is developed to examine how an operator's hand speed regulating scheme enhances the lineman's performance while the entire system works under a wireless communication channel and the slave base is under excitation. Two sets of experiments are performed when the haptic device produces no force and when the regulating haptic force is added to the master device. Performance of the system is evaluated by measuring four indices: operator's failure in completing a task, end-effector displacement, slave manipulator controller effort, and task completion time. Results indicate that adding the haptic force to the system helps linemen function more effectively when the system is subject to base-excitation and communicates through a wireless network.
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Engineering Education literature acknowledgesthat the language Academia uses to assess the abilities ofengineering students may not be the same as the languageIndustry uses to measure the abilities of new graduates at thetime they enter... more
Engineering Education literature acknowledgesthat the language Academia uses to assess the abilities ofengineering students may not be the same as the languageIndustry uses to measure the abilities of new graduates at thetime they enter the work force. It also suggests that theunderstanding and expectations of Industry may differ fromAcademia. If the language, perceptions and expectations aredifferent, so too could be Industry’s assessment of theknowledge, skills and attitudes of new engineering graduates.Consequently, Industry may need to spend additional resourcesto develop the abilities of new hires to meet their own needs.The Industry Forum III was conducted in partnership withmembers of Manitoba Industry and members of Academia fromthe Faculty of Engineering at the University of Manitoba withthe objective to develop a common language that Industry andAcademia can use in concert to measure the abilities of newengineering graduates. This paper details the findings from theforum, ...
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This article presents our recent work towards development of a controller for the new class of modernized excavators. There is an increasing demand to develop autonomous earth-moving machines that are: more efficient than the conventional... more
This article presents our recent work towards development of a controller for the new class of modernized excavators. There is an increasing demand to develop autonomous earth-moving machines that are: more efficient than the conventional ones and capable of operating with minimal supervision by operators. A fractional-order pro-portional-integral-derivative (FOPID) control is applied to a newly designed electro-hydrostatic actuator (EHA) circuit for these machines. We further employ the Oustaloup recursive method for which the parameters of the controller are chosen based on the modified Nelder-Mead optimization algorithm. Our experimental results indicate that the proposed controller is capable of controlling the speed of the link with a negligible error. This work paves the road for development of autonomous, energy efficient, off-road mobile machines.
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In this paper, we present the development of a graphical user interface for a commercially available humanoid robot to study its interaction with children. The interface has been designed to facilitate the overall operation of the robot,... more
In this paper, we present the development of a graphical user interface for a commercially available humanoid robot to study its interaction with children. The interface has been designed to facilitate the overall operation of the robot, and ultimately improve the interaction with children. Four pilot cases are studied to investigate overall effectiveness of the developed robotic setup in interacting and educating children. Case studies included communication with children in university environment, a day nursery, a junior high school, and at the Winnipeg Children's Hospital. Children and their parents/staffs were asked to provide feedback on how they/their children felt about interacting with the robot. Responses were then translated into quantitative measures. The measures received by each group of children and parents/staffs were compared using the ANOVA test. Results failed to reject the null hypothesis of equality in means of all measures. Therefore, the feedback, provided by both groups using questionnaires, was considered very close to each other. In other words, results indicated that children and parents/staffs expressed great interest in use of the developed system, and believed that such a robot could be a helpful tool in child therapy like autism.
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As a hydraulic actuator is used over time, the piston seal that closes the gap between the moveable piston and the cylinder wall wears. This results in the fluid to eventually being able to flow across the piston and between the cylinder... more
As a hydraulic actuator is used over time, the piston seal that closes the gap between the moveable piston and the cylinder wall wears. This results in the fluid to eventually being able to flow across the piston and between the cylinder chambers. Although no fluid is lost from the circuit, the dynamic performance of the system is affected since only a portion of the flow delivered to the actuator is available to move the piston against the load. Leakage across the piston introduces a flow deadband, which can lead to servoing errors. This paper presents an approach based on the cross-correlation time-series analysis to determine the health of hydraulic actuator internal seals. Pressure signals obtained directly from routine operations are analyzed using the cross-correlation function. The method presented in this paper is shown to be capable of detecting leakages as small as 0.069 l/min.
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... 1 works in constant pressure mode with a closed-center valve. ... Figure 1: Hydraulic experimental system: 1. servovalve; 2. pump with pressure regulator; 3. pressure transducer; 4 ... feedfonvard NN described as following is chosen... more
... 1 works in constant pressure mode with a closed-center valve. ... Figure 1: Hydraulic experimental system: 1. servovalve; 2. pump with pressure regulator; 3. pressure transducer; 4 ... feedfonvard NN described as following is chosen to model and predict the hydraulic servo actuator: ...
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The problem of control system design for longitudinal axis of a small-size flying wing is studied. The new controller proposed is comprised of two controllers working together to provide robust stability and step reference tracking for... more
The problem of control system design for longitudinal axis of a small-size flying wing is studied. The new controller proposed is comprised of two controllers working together to provide robust stability and step reference tracking for the nonlinear dynamics of SmartFly UAV. More precisely, Linear Quadratic Regulator (LQR) is used together with Proportional, Integral, Derivative (PID) controller. The inspiration comes from the fact that each of the mentioned controllers have advantages and disadvantages that cannot be neglected. LQR, as an optimal in terms of energy-like regulator, provides robust stability with a minimized energy-like performance index. It is also very computationally efficient. But, when it comes to the transient of particular output, LQR is not the best solution. On the other hand, PID has the advantage of a possibility to tune the gains for optimized transient behavior, especially for well-behaving plants. Furthermore, PID controller is particularly useful for tracking problems. However, PID is often not robust (in terms of parameter uncertainties) and it is also difficult to tune PID parameters for unstable systems. By differentiating between system stability and performance in the controller design process, it is possible to benefit from both controllers, using them along side together in one system. Functionality of this method was verified through computer simulation in MATLAB/SIMULINK for a nonlinear model of SmartFly UAV. Closed-loop system performance was evaluated in terms of robustness and step reference tracking.
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Abstract Surgical tool motion during microsurgery could arguably reflect surgical performance. This paper reports on how the motion of a surgical tool correlates or differs between conventional freehand surgery and robot-assisted surgery.... more
Abstract Surgical tool motion during microsurgery could arguably reflect surgical performance. This paper reports on how the motion of a surgical tool correlates or differs between conventional freehand surgery and robot-assisted surgery. In this pilot study, components of the position and orientation as well as the linear and angular velocities of a surgical tool, over the same period of operation, are compared during the two scenarios. For freehand surgery, a bipolar forceps is retrofitted with a tracking system to measure translational and rotational components of the tool motion. In robot-assisted surgery, the position and orientation components are obtained using kinematics of the neuroArm image-guided robotic system. A cross correlation analysis was used to investigate correlation between each pair of displacement or velocity components from freehand and robot-assisted scenarios to indicate how strongly or weakly two sets of data are linked together. The absolute maximum value of the cross correlation coefficient is calculated for each pair of components to quantitatively investigate the correlation between two sets of data. Results showed that the positional and rotational components, reflecting the surgical workspace, in both scenarios are correlated. However, for the cases studied, surgical tool rate of motion differs between the two scenarios. Results are important as they can be utilized to design robot-assisted neurosurgical systems that reflect characteristics of freehand surgery gained by surgeons through years of training, knowledge, and experience. Graphical Abstract
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A new approach to adaptive control of chaos in a class of nonlinear discrete-time-varying systems, using a delayed state feedback scheme, is presented. It is discussed that such systems can show chaotic behavior as their parameters... more
A new approach to adaptive control of chaos in a class of nonlinear discrete-time-varying systems, using a delayed state feedback scheme, is presented. It is discussed that such systems can show chaotic behavior as their parameters change. A strategy is employed for on-line calculation of the Lyapunov exponents that will be used within an adaptive scheme that decides on the
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Quantized dynamical entropy (QDE) has recently been proposed as a new measure to quantify the complexity of dynamical systems with the purpose of offering a better computational efficiency. This paper further investigates the viability of... more
Quantized dynamical entropy (QDE) has recently been proposed as a new measure to quantify the complexity of dynamical systems with the purpose of offering a better computational efficiency. This paper further investigates the viability of this method using five different human gait signals. These signals are recorded while normal walking and while performing secondary tasks among two age groups (young and older age groups). The results are compared with the outcomes of previously established sample entropy (SampEn) measure for the same signals. We also study how analyzing segmented and spatially and temporally normalized signal differs from analyzing whole data. Our findings show that human gait signals become more complex as people age and while they are cognitively loaded. Center of pressure (COP) displacement in mediolateral direction is the best signal for showing the gait changes. Moreover, the results suggest that by segmenting data, more information about intrastride dynamical features are obtained. Most importantly, QDE is shown to be a reliable measure for human gait complexity analysis.
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ABSTRACT
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This paper describes the development of a simulation model for studying the tip-over stability of a typical heavy-duty hydraulic log-loader machine. The model takes into account the dynamics of (i) the base that can potentially rock back... more
This paper describes the development of a simulation model for studying the tip-over stability of a typical heavy-duty hydraulic log-loader machine. The model takes into account the dynamics of (i) the base that can potentially rock back and forth, (ii) the combined vehicle suspension and ground/tire compliance, (iii) the friction between the tires and the ground, and (iv) the hydraulic actuators’ functions. The results demonstrate the effects of the manipulator movements, the flexibility of the contact between the base and the ground, the hydraulic compliance, and the friction properties between the wheels and the ground, on the stability of the machine. Particularly, it is shown that the flexibility of the contact between the base and the ground reduces the machine stability, whereas the flexibility at the manipulator joints due the hydraulic compliance improves the machine stability.
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Research Interests: Engineering, Control Engineering, Robust control, Differential Equations, Linear Model, and 15 moreActuators, Feedback, Environmental Variables, Quantitative feedback theory, Actuator, Force Feedback, Nonlinear system, Qft, Boolean Satisfiability, Hydraulic Cylinder, Electrical And Electronic Engineering, Hydraulic Machinery, Disturbance rejection, Proportional Control, and Force Control
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This paper describes an interdepartmental initiative which aimed at launching the establishment of a shared laboratory facility to support teaching courses related to control, instrumentation and Mechatronics offered by various... more
This paper describes an interdepartmental initiative which aimed at launching the establishment of a shared laboratory facility to support teaching courses related to control, instrumentation and Mechatronics offered by various engineering departments at the University of Manitoba. The paper first outlines the rationale and need for this initiation. The approaches taken so far from upgrading the existing equipment and making them available at the faculty level to purchasing modern equipment are described. Future steps towards using the facility to encourage problem based learning and teaching innovations will also be described.