Stability of a Flexible Asteroid Lander with Landing Control

Stable landing on asteroids is of considerable scientific and economic value but accompanied by huge difficulties. This paper proposes a novel flexible lander suitable for asteroids with microgravity and rugged surface. The gravity model with the artificial neural network and the surface model with the spherical harmonic method are introduced to establish the target asteroid's dynamical environment. The flexible dynamics with the discrete shell model, the collision with the spring-damping model and viscous sliding friction, and the rigid coupling with the constraint violation stabilization method are elaborated for the lander. Combining the asteroid's model with the lander's dynamics, one successful landing scenario of the lander is presented. The lander's landing stability of the final uncontrolled touching phase is studied through massive simulations. It is found that reasonable touching conditions can largely enhance the landing stability, and the lander can achieve a stable landing on the asteroid under a particular touching condition without control. The flexible lander's comparison to the rigid lander is also discussed. It is concluded that the flexible lander does have higher adaptability and lower risk in asteroid landing. What is more, the attitude controller and position controller for the lander's descent phase are also proposed and tested.