Adaptive control for space debris removal with uncertain kinematics, dynamics and states

• Dynamics model of the space debris removal via Tethered Space Robot is derived.
• Flexibility and elasticity of tether, and attitude of two satellites are included.
• A full adaptive control strategy for the space debris removal via TSR is proposed.
• The controller is with unknown kinematics, dynamics and part of the states.
• A modified controller is also presented according to the system peculiarities.

As the Tethered Space Robot is considered to be a promising solution for the Active Debris Removal, a lot of problems arise in the approaching, capturing and removing phases. Particularly, kinematics and dynamics parameters of the debris are unknown, and parts of the states are unmeasurable according to the specifics of tether, which is a tough problem for the target retrieval/de-orbiting. This work proposes a full adaptive control strategy for the space debris removal via a Tethered Space Robot with unknown kinematics, dynamics and part of the states. First we derive a dynamics model for the retrieval by treating the base satellite (chaser) and the unknown space debris (target) as rigid bodies in the presence of offsets, and involving the flexibility and elasticity of tether. Then, a full adaptive controller is presented including a control law, a dynamic adaption law, and a kinematic adaption law. A modified controller is also presented according to the peculiarities of this system. Finally, simulation results are presented to illustrate the performance of two proposed controllers.