Innovative hazard detection and avoidance guidance for safe lunar landing

Abstract

Safe planetary landing is considered a key technology for future robotic and manned planetary landing missions. The relay hazard detection and proportion–integration–differentiation avoidance guidance algorithms were used in Chang’e-3 mission, which not only increased the complexity of the guidance system, but also resulted in non-fuel-optimal avoidance guidance from the viewpoint of fuel consumption. To further develop and improve the hazard detection and avoidance scheme of Chang’e-3, novel autonomous hazard avoidance methodologies should be investigated. This paper addresses an innovative hazard detection and avoidance scheme for safe lunar landing from the following three aspects: imaging flash lidar based hazard detection, safe landing site selection strategy, and minimum-fuel hazard avoidance guidance. First, the three-dimensional imaging flash lidar, a developing three-dimensional imaging sensor, is utilized to rapidly and precisely detect three-dimensional terrain of the landing area. Second, the hazard detection and optimum landing site selection strategy inherited from Chang’e-3 are improved and enhanced to estimate the potential obstacles, and select an optimum landing site which is the guidance target of following hazard avoidance. Next, the fuel-optimal hazard avoidance guidance problem is transcribed into as a minimum-fuel consumption optimization problem using the Gauss pseudospectral method, which is easily solved by the open-source software GPOPS. Finally, the validity of the autonomous hazard detection and avoidance guidance scheme proposed in this paper is confirmed by computer simulation.