Robust event-triggered game-based attitude control for on-orbit assembly

On-orbit assembly is important in future space mission. It is a key process to adjust the attitude of substructures before assembling them into the main structure. In this paper, an event-triggered robust differential game is developed for multiple microsatellites fixed on one substructure to control the attitude of the substructure subject to disturbance. By taking disturbance as a special player to game with coordinated microsatellites, the attitude regulation problem is formulated as a robust differential game problem so that each microsatellite can independently calculate its own worst-case control strategy to reject disturbance. Considering the limited computation ability, a set of coupled algebraic equations is derived to obtain analytical expressions of Nash equilibrium strategies of microsatellites. Simultaneously, an event triggering threshold is designed by using the state error to avoid continuous communication and computation of mulitple microsatellites, and Zeno behaviour can be effectively avoided. Numerical simulations verify the effectiveness and stability of the event-triggered robust differential game method for the attitude regulation of the substructure.