Proceedings of the Canadian Engineering Education Association, 2015
This paper describes the third year of a studyat the University of Manitoba aimed at exploring ho... 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...
Proceedings of the Canadian Engineering Education Association, 2015
This paper describes the findings from athree-year longitudinal study at the University ofManitob... 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...
Publisher Summary This chapter explores fuzzy control system techniques and their application in ... 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.
SUMMARYA fundamental study on the control of hydraulically actuated robots is presented. Dynamic ... 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.
Journal of Dynamic Systems, Measurement, and Control, 1994
This paper addresses the control problem for a class of heavy-duty hydraulic machines in order to... 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...
2016 IEEE 7th Annual Information Technology, Electronics and Mobile Communication Conference (IEMCON), 2016
This paper presents the construction of a low-cost data acquisition system (DAS) prototype based ... 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.
Journal of Dynamic Systems Measurement and Control-transactions of The Asme, Nov 22, 2018
In this paper, a control scheme is developed and evaluated for stable bilateral haptic teleoperat... 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.
SUMMARYOdometry errors, which occur during wheeled mobile robot movement, are inevitable as they ... 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.
IEEE Transactions on Instrumentation and Measurement, Dec 1, 2016
One of the main faults that may happen in electrohydrostatic systems is the actuator internal lea... 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.
This paper investigates haptic-enabled teleoperation of a base-excited hydraulic manipulator work... 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.
Proceedings of the Canadian Engineering Education Association, 2015
Engineering Education literature acknowledgesthat the language Academia uses to assess the abilit... 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, ...
Proceedings of the Canadian Engineering Education Association, 2015
This paper describes the third year of a studyat the University of Manitoba aimed at exploring ho... 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...
Proceedings of the Canadian Engineering Education Association, 2015
This paper describes the findings from athree-year longitudinal study at the University ofManitob... 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...
Publisher Summary This chapter explores fuzzy control system techniques and their application in ... 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.
SUMMARYA fundamental study on the control of hydraulically actuated robots is presented. Dynamic ... 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.
Journal of Dynamic Systems, Measurement, and Control, 1994
This paper addresses the control problem for a class of heavy-duty hydraulic machines in order to... 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...
2016 IEEE 7th Annual Information Technology, Electronics and Mobile Communication Conference (IEMCON), 2016
This paper presents the construction of a low-cost data acquisition system (DAS) prototype based ... 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.
Journal of Dynamic Systems Measurement and Control-transactions of The Asme, Nov 22, 2018
In this paper, a control scheme is developed and evaluated for stable bilateral haptic teleoperat... 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.
SUMMARYOdometry errors, which occur during wheeled mobile robot movement, are inevitable as they ... 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.
IEEE Transactions on Instrumentation and Measurement, Dec 1, 2016
One of the main faults that may happen in electrohydrostatic systems is the actuator internal lea... 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.
This paper investigates haptic-enabled teleoperation of a base-excited hydraulic manipulator work... 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.
Proceedings of the Canadian Engineering Education Association, 2015
Engineering Education literature acknowledgesthat the language Academia uses to assess the abilit... 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, ...
Uploads
Papers by Nariman Sepehri