Nonlinear feedback composite control of space manipulator system with bounded torque inputs and uncertain parameters

Paper number

IAC-12,C2,1,15.p1,x14498

Author

Dr. Jie Liang, China

Coauthor

Prof. Li Chen, Fuzhou University, China

Year

2012

Abstract

With the development of the robot technology and the deepening of space exploration, more and more space robots have been applied in the exploitation of space resource. As a result of the complexity of space missions and the particularity and risk of the space environment, the space robots should have the characters of light weight, high speed and efficiency, and have robustness to the external disturbance. Moreover, due to physical limitation, the actuator outputs are constantly bounded or constrained, actuator  saturation  is  an  unavoidably nonlinear  factor  in  space robot  systems,  and  every  physical  actuator  has  inherent  constraints. When the input signals exceed such limits, the actuator saturates, causing the closed-loop performance to deteriorate and in the extreme case, to even lose stability. These practical problems have to be taken into the system controller design.
     This thesis discusses control problem of free-floating space robot system with bounded torque inputs and uncertain parameters is studied. The kinematics and dynamics of the system were analyzed by use of momentum conservation. Base on the results, a nonlinear feedback composite control scheme for free-floating space robot system with bounded torque inputs and uncertain parameters is developed. The proposed control scheme regulates the uncertain parameters by use of robust and adaptive control, and limits the input torques in a finite range by use of the continuous differentiable increasing functions，so the controller is more suitable for practical applications. Moreover, the control scheme can guarantee the stability of the system, regardless of whether the parameter-region is precise. That reflects the better robustness. The simulation results show the feasibility and efficiency of the control scheme.
Acknowledgement
This paper work is supported by the National Natural Science Foundation of China (Grant No.11072061),  Fujian Provincial Natural Science Foundation (Grant No. 2010J01003).

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IAC-12,C2,1,15.p1,x14498.brief.pdf

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