Novel Finite-Time Controller With Improved Auxiliary Adaptive Law for Hypersonic Vehicle Subject to Actuator Constraints

A novel adaptive finite-time controller (NAFTC) is proposed for flexible air-breathing hypersonic vehicle (FAHV) with actuator saturations, composing of two controllers designed for velocity and height subsystem respectively. Firstly, an adaptive dynamic inversion control is presented for velocity subsystem. The influence of actuator saturation is solved by an improved auxiliary adaptive law (IAAL). Compared with conventional adaptive law, the IAAL can achieve faster convergent speed of tracking error and weaken dramatical change for control signal effectively. Secondly, an adaptive continuous sliding mode control is designed for height subsystem, in which integral sliding surface is established based on a continuous fast higher-order sliding mode algorithm (CFSMA). Compared with conventional finite-time high-order regulator, CFSMA can drive states to converge faster and adjust respond speed of system conveniently without complicated parameters selection. Meanwhile, IAAL is combined to deal with the influence of elevator saturation. Ultimately, with the aid of NAFTC, FAHV subject to actuator constraints can also achieve faster convergent speed. In addition, NAFTC can realize higher tracking precision and faster respond speed compared with existing conventional adaptive controllers.