Mars landing feedback guidance for non-concave trajectory construction

This paper focuses on the Mars soft pinpoint landing feedback guidance to construct a non-concave trajectory for superior obstacle avoidance and camera's field of view of the landing site. More specifically, to steer the vehicle to satisfy the non-concave trajectory, an adaptive curvature guidance is developed based on a nominal curvature dynamic model. Then, an adaptive sliding mode guidance based on zero-effort-miss/zero-effort-velocity (ZEM/ZEV) guidance is proposed, which not only maintains the advantages of ZEM/ZEV guidance but also improves the robustness. Furthermore, numerical simulations are performed to verify the feasibility and effectiveness of the proposed algorithms. Moreover, by constructing a glide-slope trajectory, the terminal lateral accelerations are zeros, which can effectively avoid rollover when the vehicle touches the Mars surface.