Adaptive fault-tolerant control for the ascent phase of hypersonic vehicle with time-varying full state constraints

In this paper, a novel attitude adaptive fault-tolerant control (FTC) scheme is presented for the ascent phase of hypersonic vehicle (HSV) subject to pneumatic-propulsion coupling and time-varying full state constraints, which are unique to the ascent phase of HSV and are caused by the integrated design of fuselage engine and power system switching. Compared with some existing methods for time-varying constraints, the proposed control method contains a constrained function so that constraints can be incorporated directly into the state, which asymmetric and time-varying state constraints can be handled without feasibility conditions. Moreover, by designing a time-varying scaling function matrix to transform the tracking error, the proposed method enables the practical tracking control to be achieved without any switching for a multi-input multi-output (MIMO) pure-feedback system which is transformed from the ascent phase model of HSV. Besides, to incorporate constraints into the state, an adaptive fault estimation filter is designed to estimate unknown faults and disturbances. It is proved that the proposed FTC scheme can guarantee that the closed-loop control system is stable and the time-varying state constraints are satisfied. Finally, simulation results are provided to illustrate the effectiveness of the proposed FTC scheme.