Second-order sliding mode attitude control based on fuzzy control for hypersonic vehicle

Considering the uncertainties caused by aerodynamic parameters variation during flight, fuzzy control and second-order sliding mode control are combined to constitute fuzzy sliding mode controllers for attitude control of hypersonic vehicles. According to the singular perturbation theory, the fast and slow double closed loop syetem is designed to control angle velocity and attitude angles. The second-order sliding mode controller is designed, so as to attenuate the chattering phenomena and achieve enhanced tracking accuracy with a finite-time convergence. Then the uncertain part of the hypersonic vehicle model is approximated by the adaptive fuzzy logic to compensate for the controller effectively. Based on the Lyapunov stability theory, the adaptive law of fuzzy rule parameters is deduced and the stability of the entire control system is proved. The simulation results show that the fuzzy sliding mode control of the hypersonic vehicle can restrain the influence of the change of aerodynamic parameters effectively and track the expected attitude angle quickly and accurately. © 2019, Editorial Office of Control and Decision. All right reserved.