Fuzzy adaptive sliding mode fault estimation and fixed-time fault-tolerant control for coupled spacecraft based on SE(3)

The goal of this study is to develop fault estimation (FE) and fault tolerant control (FTC) techniques for rigidly coupled spacecraft. A fuzzy adaptive sliding mode fault estimation approach is proposed to address fault tolerance against a large scale of disturbances, including inertia parametric uncertainties, space disturbances, actuator faults and saturation constraints. Firstly, a six-degrees of freedom (6-DOF) fault tolerant control architecture is established on the Lie group SE(3), which combined rotation and translation coupling kinematics and dynamics together. Then, a nonlinear fault estimator is used to deal with controllability loss of the fault actuator and the fuzzy logic system (FLS) is presented to solve the lumped disturbance. Next, in order to reduce the number of control parameters, the exponential parameters of the fast double-power sliding mode surface and the reaching law are set to be the same, which are nested with the estimated value of actuator effectiveness and combined with the pseudo inverse control allocation method to form the control algorithm in this paper. Finally, the stability and fixed-time convergence of the proposed method are proved theoretically by Lyapunov function, and the effectiveness of the scheme is verified by numerical simulation.