Output Feedback Finite-dimensional Repetitive Learning Control on Virtual Force for Flexible-base Flexible-link and Flexible-joint Space Robot

Fu, Xiaodong; Li, CHEN

doi:10.11728/cjss2021.05.819

Cited by 3 publications

(2 citation statements)

References 14 publications

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“…Repetitive learning control is a control method with periodic repetitive motion, which has been applied in the field of exoskeleton-assisted robots and flexible space robots and shows excellent control performance [16,17]. At present, the main optimization direction of rope traction rehabilitation robots is the optimization of feedback parameters and disturbance estimation error compensation.…”

Section: Tracking Control Problem Descriptionmentioning

confidence: 99%

Periodic Disturbance Compensation Control of a Rope-Driven Lower Limb Rehabilitation Robot

Wang

Zhang

2023

Actuators

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In order to solve the external periodic disturbance and unknown dynamics influence in the passive rehabilitation process of a rope-driven lower limb rehabilitation robot, a control method with periodic repeated learning was designed. In this control method, the closed-loop dynamics are divided into a periodic disturbance term, an unknown dynamics term, and a basic term, and the shape function is designed by using the Stone–Weirstrass theorem. In the process of periodic operation, the estimated value of the shape function coefficient is repeatedly learned to obtain the periodic disturbance term approximation and to realize the compensation in advance. Through the design of the impedance learning rate, the unknown dynamic term is periodically learned, and the unknown dynamics approximation is obtained. By combining the two approximations with the basic terms which can be solved directly, the external periodic disturbance is compensated for in advance and the control precision is improved. The control algorithm was verified by simulation, and the error fluctuation of the system gradually decreases and reaches the ideal value within several cycles. The performance of the control system is stable, and the problem of limb impedance caused by different patients is well solved.

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Section: Tracking Control Problem Descriptionmentioning

confidence: 99%

Periodic Disturbance Compensation Control of a Rope-Driven Lower Limb Rehabilitation Robot

Wang

Zhang

2023

Actuators

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“…Building a dynamic model of multi-body robots with flexible links and joints has become a research hotspot to improve the analysis of the dynamic performance of flexible spatial parallel robots. Xiaodong et al [12] described the displacement field of flexible components using the hypothetical mode method, defined the deformation displacement of flexible joints based on the Spong hypothesis, and established a dynamic model of fully flexible spatial robots using the Lagrange equation. Zhang et al [13] simplified the displacement vector of a flexible joint using an elastic constraint boundary, reduced the system dimensions, and improved the system control performance.…”

Section: Introductionmentioning

confidence: 99%

Inverse Dynamics Modeling and Simulation Analysis of Multi-Flexible-Body Spatial Parallel Manipulators

Zhang

Zhao

2023

Electronics

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Taking a spatial parallel robot with flexible joints and links as the research object, a dynamic modeling method for a multi-flexible-body robot system is proposed. Its effectiveness is verified by comparing the numerical model with a simulation model. (1) Background: The elastic deformation of the flexible joints and links in the multi-flexible-body spatial parallel robot under high-speed operation and the coupling effect between the flexible and the rigid components substantially affect the system stability and trajectory accuracy. Therefore, it is necessary to analyze the dynamic characteristics of multi-flexible-body robot systems by establishing accurate dynamic models. (2) Methods: First, the finite element method was used to discretize the flexible joints and links. Subsequently, according to the floating frame of the reference coordinate method, the deformation coordinates of the flexible joints and links were described. The first six modal information were retained to develop a dynamic model considering the coupling effect between the flexible joint and rigid link and between the flexible joint and link. Second, a dynamic model of the end-effector with small displacement changes was established according to the coordination matrix. Furthermore, a dynamic model of rigid links was established based on the vector method and combined with the higher-order dynamic model of flexible joints and links to form the dynamic model of multi-flexible-body kinematic chains. Finally, the dynamic model of the three kinematic chains was assembled with that of the end-effector to obtain an accurate dynamic model of the multi-flexible-body robot systems. (3) Results: The motion trajectory of the multi-flexible-body robot floats around the fully rigid spatial parallel robot in a certain range. Its range of travel in the x, y, and z directions was 0 to 3.14, 0 to 4.06, and 0 to 0.483 mm, respectively. With increasing angular velocity, the maximum absolute amplitude of the driving torque of each branch chain also increases, whereas its motion trend remains unchanged. (4) Conclusions: The proposed dynamic modeling method and its simulation model for multi-flexible-body robots are correct, which can lay a solid foundation for further control performance analysis.

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Trajectory Tracking Hybrid Control and Vibration Suppression of Free-floating Multi-flexible Space Robot with Limited Input

Xie¹,

YU²

2023

kjkxxb

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Output Feedback Finite-dimensional Repetitive Learning Control on Virtual Force for Flexible-base Flexible-link and Flexible-joint Space Robot

Cited by 3 publications

References 14 publications

Periodic Disturbance Compensation Control of a Rope-Driven Lower Limb Rehabilitation Robot

Periodic Disturbance Compensation Control of a Rope-Driven Lower Limb Rehabilitation Robot

Inverse Dynamics Modeling and Simulation Analysis of Multi-Flexible-Body Spatial Parallel Manipulators

Trajectory Tracking Hybrid Control and Vibration Suppression of Free-floating Multi-flexible Space Robot with Limited Input

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