Fault-tolerant sliding mode attitude tracking control for flexible spacecraft with disturbance and modeling uncertainty

Xibin Cao,Ming Liu,Chengfei Yue

doi:10.1177/1687814017690341

Abstract

This article investigates the attitude tracking control problem for a class of flexible spacecraft with a redundant four reaction wheels’ setting. In this study, inertia uncertainties, external disturbance, wheel torque saturation, and configuration misalignment are taken into account simultaneously. Two types of sliding mode controllers are presented to solve this design problem. First, supposing the norm upper bound of external disturbances, bounds of inertia, and input uncertainties are available, a terminal sliding mode attitude tracking control strategy is developed, where the controller and steering laws are synthesized together. Second, supposing these norm upper bounds are unavailable, an adaptive control law is designed to cope with attitude tracking problem. Under both control schemes, the system trajectory can be ensured to arrive on the specified sliding surface in finite time. Finally, an illustrative example is given to verify the effectiveness of the proposed attitude tracking control methodologies.

Highlights

Satellite control systems refer to one of the most significant mechatronics systems, which have received extensive research attention in practical spacecraft engineering
In practical control systems, model uncertainty and nonlinearity, inertial uncertainty, external disturbance, control signal delay, and other constraints always exist inevitably,[5,6,7,8,9] and actuator alignment errors occur frequently due to finite-manufacturing tolerance or warping of spacecraft structure.[10]
These phenomena may degrade the performances of the spacecraft control systems, and a variety of designed approaches have been developed to investigate robust control design problems.[11,12,13,14,15,16]

Summary

Introduction

Satellite control systems refer to one of the most significant mechatronics systems, which have received extensive research attention in practical spacecraft engineering. To the best of the authors’ knowledge, the finite-time attitude tracking problem has not been fully investigated for flexible spacecraft with actuator misalignment, unknown inertia, and external disturbance. Based on the assumption that the bound knowledge of external disturbances and inertia and input uncertainties are known, a finite-time sliding mode control scheme is designed to solve the attitude tracking problem. In the case that these norm upper bounds are unknown, an adaptive control law is designed to revisit attitude tracking problem In light of both of these control methods, the reachability of the specified sliding surface can be guaranteed in finite time. Considering the sliding mode surface (equation (31)), the spacecraft dynamics (equation (13)) and kinematics (equation (14)) can be stabilized by the following controller u(t) = À (1 À a)À1rDT (DDT )À1 s(t) jjs(t)jj

C3 jjsjjjjve jjsjj jj ð33Þ

Conclusion