Research Of Finite-time Sliding Mode Controller And Observer Algorithm For Attitude Control Of Hypersonic Aircraft

The hypersonic vehicle presents the characteristics offast time-varying, nonlinearity and strong coupling. To meet the requirements of control accuracy and control performance for large envelope flight task, this paper is concerned with the finite-time sliding mode controller and observer of the hypersonic vehicle.Firstly, the PID type time-varying sliding mode control law is designed to deal with the shortcoming of the reaching phase inherited in the traditional PID type sliding control method. Global sliding mode manifold is achieved by introducing the time-varying items and robustness is then improved. Lyapunov method is used for analyzing the system stability. Since the accuracy of the system is decreased by the introduction of the boundary lawyer technique, finite-time sliding mode observer is designed and further incorporated into the control law to improve tracking accuracy.Secondly, a finite-time control law is proposed by combining the integral sliding mode method and the finite-time control algorithm which is based on homogeneous theory to solve the problem of the slow convergence speed under the traditional PID、PD type sliding mode control law. Then a finite-time sliding mode observer is also investigated by incorporating the method of adding power into the integral sliding surface and further introduced into the control law for improving accuracy.Finally, faced with the fact that the elastic vibration of the hypersonic vehicle has a strong effect on the rigid state, a control oriented model concerning both the rigid and elastic effect and a finite-time controller are studied. Thefinite-time sliding mode controller based on super twistingalgorithm is used for the control problem of the climbing phase. A disturbance observer is simultaneously designed for compensating the control law. And a notch filter is designed to reduce the influence of elastic vibration to therigid state and ensure the stability of the overall control system.To illustrate the above three control strategies, simulations platform is conducted to verify the effectiveness.