In the fall of 2001 we implemented a new controller design project in our Junior/Senior level con... more In the fall of 2001 we implemented a new controller design project in our Junior/Senior level controls class in Mechanical Engineering at Purdue University. The old project, which involved the identification and control of a “black box”, failed to challenge and motivate students. Our new project is the design of a controller for the point-to-point motion of a gantry crane system. Student teams modeled the gantry crane and developed a controller to meet several performance specifications. The designs were implemented in Simulink with MATLAB’s Real-Time Workshop. A competition served to further motivate the students. In the end we were very impressed with the great effort the students gave and the quality of their designs. Each group presented their design and most students stayed and asked questions for several hours.
Adaptive motion and force control of manipulators in constrained motion in the presence of parame... more Adaptive motion and force control of manipulators in constrained motion in the presence of parametric uncertainties both in the robot and contact surfaces is solved in this paper. A new constrained dynamic model is obtained to account for the effect of contact surface friction. An adaptive law is suggested with unknown parameters updated by both motion and force tracking errors
This paper presented multi-objective optimization of tip tracking control for non-collocated flex... more This paper presented multi-objective optimization of tip tracking control for non-collocated flexible beam. The desired trajectory is specified at the tip displacement of the flexible struc- ture, which undergoes translation base motion actuated by a lin- ear motor. The system model is first formulated from modal truncation approach for the flexible structure representing a sin- gle Cartesian robot manipulator. The linear system model of the flexible structure always has structural uncertainties. Robust sta- bility and robust performance on tip tracking can be expressed as H2/H∞ norm constraints, which are converted into the Linear Matrix Inequality (LMI). The multi-objective controller design is solved by the convex minimization. In order to reduce the con- servatism generated when the same Lyapunov matrix is selected, the Lyapunov matrix is scaled for different norm constraints. Simulation results have demonstrated favorable tip tracking of the proposed robust controller.
ABSTRACT The back-stepping designs based on confine functions are suggested for the robust output... more ABSTRACT The back-stepping designs based on confine functions are suggested for the robust output-feedback global stabilization of a class of nonlinear continuous systems; the proposed stabilizer is efficient for the nonlinear continuous systems confined by a bound function, the nonlinearities of the systems may be of varied forms or uncertain; the designed stabilizer is robust means that a class of nonlinear continuous systems can be stabilized by the same output feedback stabilization schemes: numerical simulation examples are given.
2010 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, 2010
Linear electrical loading system (LELS) driven by electrical cylinder with permanent magnet synch... more Linear electrical loading system (LELS) driven by electrical cylinder with permanent magnet synchronous motor (PMSM) offers several advantages of high transmission efficiency and high precision positioning, however these advantages are obtained at the expense of larger friction in mechanism and added difficulties in controlling such a force servo system. To address the problems, the LuGre friction model is modified with a smooth transition function between low speed and high speed to make the internal state steady, then the modified LuGre model is applied for dynamic friction compensation. Then a discontinuous-projection-based desired compensation adaptive robust controller (ARC) is constructed, which makes full use of the LuGre friction model in the presence of dynamic friction effects. Comparative simulation results are conducted on a LELS simulation system. The simulation results illustrate the effectiveness of the proposed scheme.
Volume 2: Systems; Micro and Nano Technologies; Sustainable Manufacturing, 2013
ABSTRACT The contour error of machining processes is defined as the difference between the desire... more ABSTRACT The contour error of machining processes is defined as the difference between the desired and actual produced shape. Two major factors contributing to contour error are axis position error and tool deflection. A large amount of research work formulates the contour error in convenient locally defined task coordinate frames that are subject to significant approximation error. The more accurate global task coordinate frame (GTCF) can be used, but transforming the control problem to the GTCF leads to a highly nonlinear control problem. An adaptive robust control (ARC) approach is designed to control machine position in the GTCF, while directly accounting for tool deflection, to minimize the contour error. The combined GTCF/ARC approach is experimentally validated by applying the control to circular contours on a three axis milling machine. The results show that the proposed approach reduces contour error in all cases tested.
a b s t r a c t Rather severe parametric uncertainties and uncertain nonlinearities exist in the ... more a b s t r a c t Rather severe parametric uncertainties and uncertain nonlinearities exist in the dynamic modeling of a parallel manipulator driven by pneumatic muscles. Those uncertainties not only come from the time- varying friction forces and the static force modeling errors of pneumatic muscles but also from the inherent complex nonlinearities and unknown disturbances of the parallel manipulator. In this paper, a discontinuous projection-based adaptive robust control strategy is adopted to compensate for both the parametric uncertainties and uncertain nonlinearities of a three-pneumatic-muscles-driven parallel manipulator to achieve precise posture trajectory tracking control. The resulting controller effectively handles the effects of various parameter variations and the hard-to-model nonlinearities such as the friction forces of the pneumatic muscles. Simulation and experimental results are obtained to illustrate the effectiveness of the proposed adaptive robust controller.
In the fall of 2001 we implemented a new controller design project in our Junior/Senior level con... more In the fall of 2001 we implemented a new controller design project in our Junior/Senior level controls class in Mechanical Engineering at Purdue University. The old project, which involved the identification and control of a “black box”, failed to challenge and motivate students. Our new project is the design of a controller for the point-to-point motion of a gantry crane system. Student teams modeled the gantry crane and developed a controller to meet several performance specifications. The designs were implemented in Simulink with MATLAB’s Real-Time Workshop. A competition served to further motivate the students. In the end we were very impressed with the great effort the students gave and the quality of their designs. Each group presented their design and most students stayed and asked questions for several hours.
Adaptive motion and force control of manipulators in constrained motion in the presence of parame... more Adaptive motion and force control of manipulators in constrained motion in the presence of parametric uncertainties both in the robot and contact surfaces is solved in this paper. A new constrained dynamic model is obtained to account for the effect of contact surface friction. An adaptive law is suggested with unknown parameters updated by both motion and force tracking errors
This paper presented multi-objective optimization of tip tracking control for non-collocated flex... more This paper presented multi-objective optimization of tip tracking control for non-collocated flexible beam. The desired trajectory is specified at the tip displacement of the flexible struc- ture, which undergoes translation base motion actuated by a lin- ear motor. The system model is first formulated from modal truncation approach for the flexible structure representing a sin- gle Cartesian robot manipulator. The linear system model of the flexible structure always has structural uncertainties. Robust sta- bility and robust performance on tip tracking can be expressed as H2/H∞ norm constraints, which are converted into the Linear Matrix Inequality (LMI). The multi-objective controller design is solved by the convex minimization. In order to reduce the con- servatism generated when the same Lyapunov matrix is selected, the Lyapunov matrix is scaled for different norm constraints. Simulation results have demonstrated favorable tip tracking of the proposed robust controller.
ABSTRACT The back-stepping designs based on confine functions are suggested for the robust output... more ABSTRACT The back-stepping designs based on confine functions are suggested for the robust output-feedback global stabilization of a class of nonlinear continuous systems; the proposed stabilizer is efficient for the nonlinear continuous systems confined by a bound function, the nonlinearities of the systems may be of varied forms or uncertain; the designed stabilizer is robust means that a class of nonlinear continuous systems can be stabilized by the same output feedback stabilization schemes: numerical simulation examples are given.
2010 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, 2010
Linear electrical loading system (LELS) driven by electrical cylinder with permanent magnet synch... more Linear electrical loading system (LELS) driven by electrical cylinder with permanent magnet synchronous motor (PMSM) offers several advantages of high transmission efficiency and high precision positioning, however these advantages are obtained at the expense of larger friction in mechanism and added difficulties in controlling such a force servo system. To address the problems, the LuGre friction model is modified with a smooth transition function between low speed and high speed to make the internal state steady, then the modified LuGre model is applied for dynamic friction compensation. Then a discontinuous-projection-based desired compensation adaptive robust controller (ARC) is constructed, which makes full use of the LuGre friction model in the presence of dynamic friction effects. Comparative simulation results are conducted on a LELS simulation system. The simulation results illustrate the effectiveness of the proposed scheme.
Volume 2: Systems; Micro and Nano Technologies; Sustainable Manufacturing, 2013
ABSTRACT The contour error of machining processes is defined as the difference between the desire... more ABSTRACT The contour error of machining processes is defined as the difference between the desired and actual produced shape. Two major factors contributing to contour error are axis position error and tool deflection. A large amount of research work formulates the contour error in convenient locally defined task coordinate frames that are subject to significant approximation error. The more accurate global task coordinate frame (GTCF) can be used, but transforming the control problem to the GTCF leads to a highly nonlinear control problem. An adaptive robust control (ARC) approach is designed to control machine position in the GTCF, while directly accounting for tool deflection, to minimize the contour error. The combined GTCF/ARC approach is experimentally validated by applying the control to circular contours on a three axis milling machine. The results show that the proposed approach reduces contour error in all cases tested.
a b s t r a c t Rather severe parametric uncertainties and uncertain nonlinearities exist in the ... more a b s t r a c t Rather severe parametric uncertainties and uncertain nonlinearities exist in the dynamic modeling of a parallel manipulator driven by pneumatic muscles. Those uncertainties not only come from the time- varying friction forces and the static force modeling errors of pneumatic muscles but also from the inherent complex nonlinearities and unknown disturbances of the parallel manipulator. In this paper, a discontinuous projection-based adaptive robust control strategy is adopted to compensate for both the parametric uncertainties and uncertain nonlinearities of a three-pneumatic-muscles-driven parallel manipulator to achieve precise posture trajectory tracking control. The resulting controller effectively handles the effects of various parameter variations and the hard-to-model nonlinearities such as the friction forces of the pneumatic muscles. Simulation and experimental results are obtained to illustrate the effectiveness of the proposed adaptive robust controller.
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