Adaptive Control Method for Flexible Landing of Asteroid with Multiple Constraints

When the spacecraft attaches to the surface of an asteroid, the spacecraft is easy to rebound and capsize in the rigid landing. In this paper, a flexible landing mode is adopted. The flexible detector can consume the residual kinetic energy generated by the collision, and effectively avoid the capsize and rebound of the detector when it lands by increasing the surface area of contact with the asteroid. This paper mainly does the following work. On the premise of retaining the flexible characteristics, the structure of the flexible lander is simplified, and the approximate model of the flexible lander is established, which not only had the flexible characteristics but also could estimate and control the state of its landing process. A robust optimal control method is designed for system modeling errors and external time-varying disturbances, and an appropriate performance function is introduced to transform the robust control problem into an optimal control problem, and the equivalence of the two problems is proved. The adaptive dynamic programming method with a single evaluation network is used to approximate the optimal control law and the optimal performance function, so that the spacecraft can effectively track the given reference trajectory under multiple disturbances. Finally, the Lyapunov method is used to analyse the stability of the designed controller, and the effectiveness of the proposed control strategy is verified by numerical simulation.