Sliding-mode based adaptive fault tolerant control for re-entry reusable launch vehicle

Two sliding-mode based fault tolerant control schemes are proposed for attitude dynamic tracking problem of re-entry reusable launch vehicle (RLV) under actuator fault, unknown uncertainty, external disturbances, and input limitation. Firstly, the mathematical model of reentry RLV with loss of actuator effectiveness fault is presented. Then, a novel control algorithm is provided for stable control in both faulty and fault-free situations. Based on adaptive control theory, an adaptive fault tolerant control (AFTC) algorithm is proposed, which removes the conventional assumption of the known upper bound of disturbances. Further, both of the control algorithms were proved stable according to Lyapunov stability theory. In the end, by taking input limitation and chattering into considerations, a numerical example of X-33 is presented to validate the effectiveness of AFTC scheme. Numerical results indicate that the proposed controller could not only achieve stable attitude dynamic tracking control without significant chattering, but also be proven to be strong in robustness against various disturbances and actuators' fault.