The SDRE based second order integral sliding mode control for attitude of reentry vehicle

In this paper, a state dependent Riccati equation-based second order integral sliding mode control(SSOISMC) algorithm is proposed for the reentry vehicle with a strong coupling, nonlinearity and uncertainty. Firstly, the state dependent Riccati equation (SDRE) controller is developed to approach the attitude controller for the nonlinear reentry vehicle without uncertainties. Then the second order integral sliding mode control theory is proposed to combine sliding mode with SDRE, and it is applied to reentry vehicle with parameter variations or external disturbances. The achievement of the second order sliding phase is proved. By the proposed control law, the optimal performance index is achieved and the uncertainties are rejected, furthermore, the chattering is alleviated. Finally, simulation is made through the assumption that aerodynamic parameters and atmospheric density are perturbed. The validity and robustness of the proposed strategies are verified by simulation results.