Command filtered backstepping control for hypersonic vehicle

Considering an air-breathing hypersonic vehicle longitudinal nonlinear model containing uncertain perturbation term, a backstepping controller is designed based on command filter. The vehicle model is decomposed as flight-path angle subsystem and velocity subsystem and is translated into the strict feedback form. Dynamic inversion method is used in the backstepping design of virtual control variable of each step, and the errors generated in the process of command filtering are compensated. Command filter is utilized to obtain the first derivative of virtual variable, which solves the explosion of differentiation terms problem in backstepping control and introduces the amplitude, rate and bandwidth constraints of virtual control variable as well as actual control variable. The extended state observer (ESO) is put forward to estimate and compensate the uncertain items in the model, which guarantees that the close-loop system possesses good control performance in existence of parameter uncertainty and external disturbance. Simulation results demonstrate that the velocity and flight-path angel reference signals can be tracked stably by using the designed controller in the presence of deviations of the vehicle general and aerodynamic parameters.