Rigid Spacecraft Fault-Tolerant Control Using Adaptive Fast Terminal Sliding Mode

In addition to the robustness against inertia uncertainty and external disturbances, the efficient and quick fault-tolerant property is expected by the on-board attitude controller for any spacecraft mission. In comparison to the active fault tolerant control methods, the passive fault-tolerant methods are simpler and require less computation time and power. The finite-time sliding mode using the terminal sliding mode has been proven the efficacy to address the attitude control related issues, but in most of the cases, fault-tolerant issues were not taken into account. The objective of the chapter here is to propose a passive fault-tolerant control by using the finite-time sliding mode control. Firstly, an extensive review has been given to discuss the application of terminal sliding mode and its variants for the attitude control problem. Then, in control design, a non-singular fast terminal sliding mode has been integrated together with the adaptive control, and an adaptive non-singular fast terminal sliding mode control has been designed. In most of the finite time fault-tolerant designed using terminal sliding modes, the controllers gains are remain to constant; which can be cause for chattering. Therefore, to limit the chattering effect, and to avoid the need of upper bounds of uncertainty and external disturbances, adaptive estimate laws have been designed to estimate the controller’s gains. Finite time stability has been analyzed by the Lyapunov theorem. Further, to show the fault-tolerance effectiveness of the proposed control law in attitude stabilization and tracking, various simulation results have been presented. The proposed control law is quick, and robust enough to negate the effects of external disturbances, mass inertia uncertainty, and actuator faults.