Dynamics modeling and model selection of space debris removal via the Tethered Space Robot

This work proposes a scheme to select a proper dynamics model for space debris removal which is captured by a Tethered Space Robot. A proper dynamics model is crucial for the parameters estimation and controller design in a Tethered Space Robot mission, in particular, for the retrieval or de-orbiting of uncooperative target. A new dynamics model of the system is derived by treating the base satellite and the space debris as rigid bodies in the presence of offsets, and with the effect of the tether's flexibility and elasticity. Then the equations of motion are simplified based on the attitude analysis and numerical simulations in different cases. It is concluded that in the Tethered Space Robot's mission, the strong coupled attitude motions among the base, target satellites, and the tether cannot be ignored during the retrieval, which is totally different from the traditional tethered satellite system. The attitude motions of the system in different conditions are discussed respectively, and a method of the model selection of the system during post-capture and retrieval/de-orbiting phase is proposed, which is a balance of the accuracy and facility. Finally, a control scheme is used to prove this conclusion.