Design of LPV sliding mode controller for hypersonic vehicle based on the upper bound of uncertainty

Abstract

Hypersonic vehicle has uncertainties in the system during maneuvering and is susceptible to external disturbances. If traditional state feedback control methods are used, the closed-loop control system is likely to cause oscillations and cannot meet the accuracy requirements of maneuvering flight command signal tracking. If the traditional sliding mode control method is used, the control system is not easy to implement due to the singular value problem in the system and the complicated calculation process. In view of the above problems, considering the actual requirements of high-speed maneuvering flight control, this paper proposes a linear variable parameter (LPV) sliding mode controller design method based on the upper bound of uncertainty and applied to hypersonic flight control. Firstly, regardless of system uncertainty and external disturbances, the traditional state feedback control method is used to keep the system stable. Then, in the presence of disturbances, by selecting a special sliding function, a sliding mode control law based on the upper bound of uncertainty is designed. In order to reduce the chattering phenomenon of the system, the relay characteristics of the system are used to introduce a continuous function to replace the sign function in the control law. The theoretical derivation proves that all the signals in the closed-loop system are bounded, and the tracking error can be controlled within a small neighborhood of the zero point. The simulation results show that the state variables can track the reference command signal stably, and effectively suppress the oscillation of the closed-loop system, which verifies the effectiveness of the controller designed in this paper.