Parameters estimation of space debris captured by tethered robotic system

This paper presents a new scheme for on-line inertia parameters estimation for a rigid space debris captured by a tethered robotic system, based on a new dynamics model of the system where the base satellite and the space debris (target) are modeled as rigid bodies and the attachment points of the tether are offset from the centers of mass of the two bodies. In the proposed algorithm, the chaser and target are modeled as rigid bodies, the latter with unknown inertia parameters. Then, the parameters identification problem is formulated and solved. First, we analyze the planar motion of the target satellite and the tether based on the proposed rigid body model. Then, the oscillations of the tether and target satellite during the post-capture phase are used to estimate the inertia parameters of the unknown satellite under the circumstances that all the information of the target is not communicated to the chaser spacecraft or the terminal robotic device due to it is an uncooperative target. At last, a robust variable forgetting factor recursive least-squares algorithm is involved to identify the moments of inertia and the offsets of the uncooperative target.