Twist Suppression Method of Tethered Towing for Spinning Space Debris

Towing spinning debris in space is subjected to the risk of twist, increasing the likelihood of collision. To reduce the twist potential, a twist suppression method is proposed for the viscoelastic tether in this paper. The system two-dimensional model is explored taking into account the attitude of the two end bodies and the tether slackness. The twist model describing the twist length is established to investigate the tension change during twist. The impedance based tension controller is designed to regulate tension actively by altering the tether unstretched length. Three cases where the thrust is 1 N, 2 N, and 5 N are studied to validate the feasibility of the method. It is shown that without tension control, towing removal is challenging for the system owing to the twist potential and large tension induced. However, the twist length is reduced dramatically and the relative distance of the two bodies is maintained under the tension control. It is also shown that the controller is robust to the measurement noise, and its performance is better for the lager thrust.