Optimal Oscillation Suppression Control for Tether Sling-Shot System

Abstract

A tether sling-shot system composed of a hub and a payload connected with a long tether is one example of space transportation systems. The facility is located at an arbitrary place on a rotating body. In this paper, the three-dimensional dynamics model for a tether sling-shot system whose hub can be inclined is presented. Tether oscillation stabilization is required to inject a payload to a predetermined orbit. Because the dynamics are complexly nonlinear, linear control methods such as the linear quadratic regulator (LQR) cannot show good performance for oscillation stabilization of the system. To overcome this problem, in this study, a model predictive control (MPC) method is chosen for stabilization. The performance of the MPC method is compared to that of suboptimal control based on (LQR) control. It is verified by numerical simulations that the MPC method can achieve faster stabilization along with smaller oscillation than the LQR control method.