Sliding mode variable structure control for the deployment of tethered satellite system

To enhance the interference immunity of the deployment of tethered satellite system (TSS), we propose a trajectory tracking method based on sliding-mode variable structure control. Firstly, the dynamic model of TSS is developed by considering both the atmosphere perturbation term and the model-less perturbation term. Secondly, in a two-stage deployment project, the ideal nominal trajectory is designed with the optimal oscillation damping tension control law in the first stage and with the equal time tension control law in the second stage. Parameters obtained in both stages are optimized by using the genetic optimization algorithm. To realize the robust trajectory tracking, we design the sliding-mode variable structure controller with the equivalent control method and the switching control method in which the continuous function power reaching law is adopted to implement the switching control. Simulation results shows that the proposed control method can efficiently improve the dynamic performance and enhance the robustness of the deployment of TSS.