Capture control of multi-agent tether-net systems based on higher-order sliding mode

Abstract:

To deal with the threat of space debris to on-orbit spacecraft, modular docking systems are added to the four-corner autonomous maneuvering units of the flexible net capture system. The units can assemble into a combined towing spacecraft, which is convenient for the implementation of subsequent deorbiting tasks, effectively preventing target escape and increasing the capture success rate. Firstly, to address the vibration problem caused by the flexible tether net in the on-orbit capture process and the challenges in coordinated actuation of the four-corner autonomous maneuvering units, a new control method is designed by combining the higher-order sliding mode algorithm with the consensus formation cooperative strategy. Secondly, the single-degree-of-freedom simulation analysis of dynamic model of the tether net capture system based on the mass concentration method is carried out. The control effect and fuel consumption of different sliding mode algorithms and the algorithm in this paper are compared. Finally, the optimal control combination of the super-twisting sliding mode algorithm and the leader-follower multi-agent consensus method is established, and successfully applied to the full-degree-of-freedom on-orbit capture simulation. The simulation results show that the new controller can complete the on-orbit capture of the target within 50 s, which exhibits excellent robustness and effectiveness. At the same time, the four-corner autonomous maneuvering units can keep the attitude angle fluctuation less than 3° during the capture process, which fully meets the objective conditions for docking systems of autonomous maneuvering units. The research effectively connects the transition between the on-orbit capture stage and the deorbit towing stage.