Research on Angle and Stiffness Cooperative Tracking Control of VSJ of Space Manipulator Based on LESO and NSFAR Control

Ye Ye,Hong Hong,Dong Dong

doi:10.3390/electronics8080893

Ye Ye, Hong Hong + Show 1 more

Open Access

https://doi.org/10.3390/electronics8080893

Copy DOI

Journal: Electronics	Publication Date: Aug 13, 2019
Citations: 3	License type: CC BY 4.0

Affiliation: Space Engineering University

Abstract

With the increase in on-orbit maintenance and support requirements, the application of space manipulator is becoming more promising. However, how to control the vibration generated by the space manipulator has been a difficult problem to be solved. The advent of variable stiffness joint (VSJ) has brought about a dawn in solving this problem. But how to achieve coordinated control of joint angle and stiffness is still a problem to be solved, especially when considering system model parameter uncertainty, unknown disturbance and control input saturation. In order to realize the controllable attenuation of the vibration of the space flexible manipulator based on the variable stiffness joint, the dynamic model of the variable stiffness joint was constructed. Then the linear transformation and feedback linearization method are used to transform its complex nonlinear dynamic model system into a pseudo-linear system containing aggregate disturbance and input saturation constraints. This paper constructs a linear extended state observer (LESO) for estimating the state of unknown systems in pseudo-linear systems. Based on the idea of state feedback control, a Neural State Feedback Adaptive Robust (NSFAR) control is constructed by using Radial Basis Function Neural Network. The adaptive input saturation compensation control law is also designed by using Radial Basis Function Neural Network to deal with the input saturation compensation problem. The ultimate uniform bounded stability of the constructed system is proved by the stability analysis based on Lyapunov function. Finally, the effectiveness and superiority of the constructed tracking algorithm are verified by compared simulation and semi-physical experiment.

Highlights

Nowadays, with the increasing frequency of space activities, the impact of spacecraft being hit by space debris has occurred
In order to solve the problem of controllable attenuation of the vibration of the flexible space manipulator after collision with the target, the variable stiffness joint (VSJ) is introduced to construct the flexible space manipulator and its dynamic model
Because its dynamic model is a complex nonlinear system, the original dynamic equation is transformed into a pseudo-linear system with integral chain type of input saturation constraint and matching lumped disturbance by means of coordinate transformation and feedback linearization

Summary

Introduction

With the increasing frequency of space activities, the impact of spacecraft being hit by space debris has occurred. A large amount of space debris has already seriously threatened the safety of on-orbit spacecraft. The large number of large-scale space debris may change the attitude and orbit of spacecraft and even cause the spacecraft to be completely destroyed. In order to solve such problems, the development of space debris removal technology has become urgent. Among the many active space removal technologies, the technology of space manipulator removal in orbit has received extensive attention. The ETS-VII of Japan, the Orbital Express of the United States, and the SY-7 of China have successively conducted verification experiments on this technology in space, and are still intensifying their research [2,3]

Methods

Results

Discussion

Conclusion