Iterative Learning-Based Tension Feedback Control for Multiple Deployments of Tethered Satellite System

A tethered satellite system is a typical underactuated nonlinear system. In this article, an ILC-based tension feedback controller is proposed to address the multiple stable deployments problem of the tethered satellite system under repetitive disturbances. It is challenging to control the repetitive deployment only with the tension, which exhibits nonnegative characteristic. Thus, a tension shifting strategy is proposed to transform such a constraint into a symmetric control domain. Iterative learning and sliding mode control methods are employed to handle disturbances. The stability analysis of the closed-loop system is proved via Lyapunov theory. The learning convergence along the iteration axis is analyzed based on the composite energy function. Finally, a ground-based experimental system is developed based on the dynamic similarity principle. Numerical simulations and experimental tests validate the feasibility and effectiveness of the proposed method.