Adaptive robust control for free-floating space robot with unknown uncertainty based on neural network

Zhang Wenhui,Huo Mingying,Huang Jiacai,Li Hongsheng,Ye Xiaoping

doi:10.1177/1729881418811518

Abstract

It is difficult to obtain a precise mathematical model of free-floating space robot for the uncertain factors, such as current measurement technology and external disturbance. Hence, a suitable solution would be an adaptive robust control method based on neural network is proposed for free-floating space robot. The dynamic model of free-floating space robot is established; a computed torque controller based on exact model is designed, and the controller can guarantee the stability of the system. However, in practice, the mathematical model of the system cannot be accurately obtained. Therefore, a neural network controller is proposed to approximate the unknown model in the system, so that the controller avoids dependence on mathematical models. The adaptive learning laws of weights are designed to realize online real-time adjustment. The adaptive robust controller is designed to suppress the external disturbance and compensate the approximation error and improve the robustness and control precision of the system. The stability of closed-loop system is proved based on Lyapunov theory. Simulations tests verify the effectiveness of the proposed control method and are of great significance to free-floating space robot.

Highlights

With the development of space technology, space robots are playing an increasingly important role
It is of great significance to study free-floating space robot (FFSR).[1,2,3]
An adaptive robust control method base on neural network adaptive robust control is proposed for the unknown FFSR with interferences

Summary

Introduction

With the development of space technology, space robots are playing an increasingly important role. Unlike the robot with fixed base on the ground, the space robot base is floating freely and belongs to a rootless multi-body system. It has dynamic coupling between the floating base and each member of the manipulator, and its space liquid fuel consumption causes some disturbance to the system, it has stronger coupling and nonlinearity than ground robot. Many control methods applied to ground robot are difficult to achieve satisfactory control results in space robot. Space fuel directly determines the operating life of space robots, so it is very precious. It is of great significance to study free-floating space robot (FFSR).[1,2,3]

Methods

Conclusion