Disturbance rejection sliding mode control of hypersonic vehicle based on backstepping method

A kind of disturbance rejection sliding mode control based on backstepping method was studied for trajectory tracking control problem of hypersonic flight vehicle in the presence of uncertain parameters and external disturbances. The nonlinear hypersonic vehicle dynamics model was translated into the strict feedback form under reasonable hypothesis. Sliding-mode control was used in the design of each step. The parameters uncertainty and external disturbances were regarded as disturbance to the system. Directed at the disturbances problem, the estimate method using extended state observer was put forwards. The disturbances were compensated in the controller based on the value estimated. The estimate value of disturbance from extended state observer was in a small neighborhood of the true value, so that the compensating effect can be guaranteed. The simulation based on the nonlinear model under 0.5° additional angle and 25% aerodynamic coefficient offset validates the disturbances rejection ability and good tracking performance of the closed loop system.