Design for aerocraft attitude control system based on feedback-linearization and variable-structure-control

There exist strong nonlinearity and coupling while the aerocrafts attitude angle is large. So the traditional approximative linearization method based on small disturbance faces difficulties. In this paper, the attitude channel of aerocraft was decoupled into three SISO linear systems by means of feedback-linearization. Then variable-structure-controller was designed based on the theory of decentralized sliding mode control with respect to each attitude channel, so as to obtain robustness to perturbation and disturbance. Theoretical research and numerical simulation indicate that the control system designed in this paper works properly even if in the case of large attitudes of aerocraft. At the same time, the control system is robust to perturbation and disturbance. It is necessary to point out that matching conditions are always satisfied in the case of the SISO system which state variables are phase variables, so the invariance of the sliding mode to uncertainties holds at all time.