Drag-based composite continuous nonsingular terminal sliding mode control method design for Mars entry trajectory tracking

This paper investigates the drag-based trajectory tracking control problem for Mars entry vehicles. A composite continuous nonsingular terminal sliding mode controller based on finite-time disturbance observer is proposed for Mars entry trajectory tracking. The proposed controller not only eliminates the effects of disturbances due to the uncertainties of atmospheric models and vehicle aerodynamics, but also guarantees the continuity of control action. Simulation results show that the proposed method improves the disturbance rejection performance and tracking precision significantly.