Command Filter Based on Back-stepping Control for Deployment of an Electrodynmaic Tether System

This paper studies back-stepping control for deployment of an electrodynamic tether system with the consideration of known upper bound of external disturbances. Command filter design is developed to achieve the controller, which can remove the inherent problem of "explosion of complexity" in back-stepping. The hybrid control of current and tension methods based on the back-stepping method is adopted to stabilize the motions of electrodynamic tether system during its deployment by regulating the tension and electric current in the tether, independent of propulsion to deploy the tether to the specified length. Furthermore, the Lyapunov analysis is used to gain a deep understanding of the characteristics of the designed hybrid control laws. Finally, the simulation results demonstrate that the proposed control laws can realize the tether fast and stable deployment.