Detumbling control of an underactuated tethered satellite system based on a tension regulation method

When using the net capturing method to remove a space debris object, a maneuverable chaser satellite ejects a tethered net to capture a target, forming a tethered satellite system. Tumbling of the target and tether libration due to the residual angular momentum of the target and the flexibility of tethers, respectively, are the main issues in the tethered system. In this paper, a reel-in/out mechanism is introduced to the system so that the tether length between the chaser and the target can be controlled. A variable-length dynamic model based on the discrete mass–spring–damper method is developed to support the tether length control. A tension regulation control strategy, coordinated with propulsion control and tether length control, is proposed to address the two main issues. Compared to the previous detumbling strategies, although this method requires more hardware resources, it takes advantage of safe implementation with the taut state tether. Numerical simulations demonstrate that the proposed tension regulation control approach outperforms the propulsion control method as well as the attitude control method in terms of detumbling efficiency and tether libration suppression. Overall, this newly proposed detumbling strategy is highly recommended for the safe execution of active debris removal missions.