Deployment control of a tethered satellite system for rendezvous with a target

Abstract

This paper considers deployment control of a tethered satellite system (TSS) for rendezvousing a subsatellite with a target object orbiting at a lower altitude. Contrary to past studies that considered a linear quadratic regulator (LQR), in the present study, an LQR-based controller is designed using a pole assignment shift technique, in which the acceleration of the tether deployment or retrieval is treated as the control input and no propellant is used. For simplicity, the TSS is represented as a dumbbell model. The tether tension is calculated based on the tether state variables (tether length, tether length rate, tether angle, tether angle rate, and acceleration of the tether deployment treated as the control input) in order to confirm whether or not tether slack occurs. The experimental results show that the proposed control law contributes to reducing the difference between the desired and experimental tether librational motions.