An improved chattering-free sliding mode control with finite time convergence for reentry vehicle

A nonlinear robust flight control strategy is proposed to solve the robust attitude control problem for the reentry vehicle. Firstly, a time-varying sliding surface with finite time convergence and the corresponding chattering-free sliding mode control are designed respectively. The time-varying function can guarantee global robustness, and the chattering phenomena can be eliminated by using the low pass filter(LPF). Then, a high-order sliding mode observer is adopted to estimates the system disturbances and the attitude rate. Thus, an observer based control scheme is achieved. Finally, some simulations are shown to illustrate the effectiveness of the proposed strategy as well as the system robustness.