Longitudinal vibration adaptive sliding mode control of space tether system at post-capture stage

The phenomenon of tether slack caused by the tether longitudinal vibration at post-capture stage is studied in this paper and adaptive sliding mode controller is designed correspondingly to suppress the longitudinal vibration of flexible tether. Firstly, the dynamic model of the space tether system (STS) is derived from the Lagrangian equation, to calculate the conditions of swinging capture, such as the length of tether and angular speed of swing. Then, the phenomenon of tether longitudinal vibration caused by mass junction on tether tip is studied, it indicates that such impact may cause tether slack and threaten the safety of STS. Subsequently, adaptive sliding mode controller is developed to suppress the tether longitudinal vibration and stability analysis through Lyapunov theory is performed on un-cooperation target capture with mass uncertainty for a more general case. Finally, simulation result and its analysis demonstrate preliminarily that the proposed controller is effective and efficient to suppress tether longitudinal vibration.