Modern applications of robotics typically involve a robot control system with an inner PI (proportional-integral) or PID (proportional-integral-derivative) control loop and an outer user-specified control loop. The ex...
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ISBN:
(纸本)9789881563910
Modern applications of robotics typically involve a robot control system with an inner PI (proportional-integral) or PID (proportional-integral-derivative) control loop and an outer user-specified control loop. The existing outerloop controllers, however, do not take into consideration the dynamic effects of robots and their effectiveness relies on the ad hoc assumption that the inner PI or PID control loop is fast enough, and other torque-based control algorithms cannot be implemented in robotics with closed architecture (i.e., the torque control loop is closed). In this paper, we propose a dynamic modularity approach to resolve this issue, and a class of adaptive outerloop control schemes is proposed for robotic systems with an inner/outer loop structure and their role is to generate joint velocity and position commands for the low-level joint servoing loop. Without relying on the ad hoc assumption that the joint servoing is fast enough or the modification of the low-level joint controller structure, we rigorously show that the proposed outerloop controllers can ensure the stability and convergence of the closed-loop robotic system. We also propose the outerloop version of the standard Slotine and Li adaptive controller in joint space, and a promising conclusion may be that most torque-based adaptive controllers for robots can be redesigned to fit the inner/outer loop structure, by using the adaptively scaled dynamic compensation and the new definition of the joint velocity command. Simulation results are provided to show the performance of the proposed adaptive outerloop controllers, using a three-DOF (degree-of-freedom) manipulator.
Modern applications of robotics typically involve a robot control system with an inner PI(proportional-integral) or PID(proportional-integral-derivative) control loop and an outer user-specified control loop. The exis...
详细信息
ISBN:
(纸本)9781509009107
Modern applications of robotics typically involve a robot control system with an inner PI(proportional-integral) or PID(proportional-integral-derivative) control loop and an outer user-specified control loop. The existing outerloop controllers,however, do not take into consideration the dynamic effects of robots and their effectiveness relies on the ad hoc assumption that the inner PI or PID control loop is fast enough, and other torque-based control algorithms cannot be implemented in robotics with closed architecture(i.e., the torque control loop is closed). In this paper, we propose a dynamic modularity approach to resolve this issue, and a class of adaptive outerloop control schemes is proposed for robotic systems with an inner/outer loop structure and their role is to generate joint velocity and position commands for the low-level joint servoing loop. Without relying on the ad hoc assumption that the joint servoing is fast enough or the modification of the low-level joint controller structure, we rigorously show that the proposed outerloop controllers can ensure the stability and convergence of the closed-loop robotic system. We also propose the outerloop version of the standard Slotine and Li adaptive controller in joint space, and a promising conclusion may be that most torque-based adaptive controllers for robots can be redesigned to fit the inner/outer loop structure, by using the adaptively scaled dynamic compensation and the new definition of the joint velocity command. Simulation results are provided to show the performance of the proposed adaptive outerloop controllers, using a three-DOF(degree-of-freedom) manipulator.
Unpredictable and time-variable adhesion force between the rubber unstacking robot and the rubber block is generated, which makes it difficult for the robot to smoothly complete the rubber disassembly task, thereby br...
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Unpredictable and time-variable adhesion force between the rubber unstacking robot and the rubber block is generated, which makes it difficult for the robot to smoothly complete the rubber disassembly task, thereby bringing about new robot control problems. For solving the above problems, a novel method of inner/outer loop impedance control based on natural gradient actor-critic (NAC) reinforcement learning is proposed in this paper. The required impedance is applied by the inner/outer loop impedance control with time delay estimation, which can correct the modeling error and compensate the nonlinear dynamics term to improve the computational efficiency of the system. In addition, the NAC reinforcement learning algorithm based on recursive least squares filtering is used to optimize the impedance parameters online, which can improve the impedance accuracy and robustness in the unstructured dynamic environment. At the same time, three stability constraints of the control strategy are derived in the analysis process. Finally, by setting up the experimental platform, it is verified that the control strategy can make the robot work smoothly under the action of unpredictable and time-variable adhesion force to reduce vibration and improve rubber unstacking performance.
Most industrial/commercial robots typically employ an unmodifiable inner joint controller and only the joint position or velocity command can be designed by the user. In this paper, we propose a robust approach to the...
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ISBN:
(纸本)9781538629185
Most industrial/commercial robots typically employ an unmodifiable inner joint controller and only the joint position or velocity command can be designed by the user. In this paper, we propose a robust approach to the control of such robotic systems with the uncertainty and nonlinearity being taken into consideration. We develop robust outerloop controllers that can rigorously ensure the uniform ultimate boundedness of the closed-loop system, without relying on the ad hoc assumption of the conventional kinematic controller that the effects of the dynamics can be neglected. The performance of the proposed robust outerloop controllers is shown by numerical simulations with a three-DOF（degree-of-freedom） manipulator.
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