Barrier Lyapunov Function-Based Planetary Landing Guidance for Hazardous Terrains

The landing guidance based on the barrier Lyapunov function (BLF) for hazardous terrains is investigated. Three suitable spatial geometric shapes (frustum-shape, cone-shape, and n -step-shape) have been chosen to describe the possible obstacles on the planetary surface. Next, a novel and general form of the barrier function (BF) has been developed using selected spatial geometric shape information, specifically designed to constrain the lateral motion. For these three different spatial geometric shapes, only the segment number of BF is different, and the segment number is determined by the spatial geometric shape. Furthermore, a fixed-time convergent function is selected as the upper boundary to coordinate the vertical motion, guaranteeing that the lander completes the landing mission within the predefined time. Next, a new nonlinear feedback guidance is designed using the asymmetric BLF constructed by the BF, keeping the lander from colliding with the obstacle and achieving the pinpoint soft landing. Finally, numerical simulations with different hazardous terrains are performed to verify the feasibility and effectiveness of the proposed algorithms.