Integrated pose control of tethered space robot in approaching process

The coordinated control of a tethered space robot in its approaching process has always been a focus of research. In order to compensate for the deficiency of traditional methods in precision and fuel consumption, a new pose coupling dynamic model is built in this paper which takes into consideration the distributed mass of the tether and the distributed force acting on the tether based on the Hamilton principle. Secondly, a hp-adaptive pseudospectral method is utilized to obtain the minimum-fuel trajectory and the corresponding ideal input. Finally, a PD controller is employed to ensure that the practical state can track the designed trajectory. Thus, an integrated closed-loop pose control of the tethered space robot is achieved. The simulation results show that in the case of existing 0.1 m initial length deviation and 5° initial angular deviation, the closed-loop controller designed in this paper can realize the effective control of the system state. Furthermore, compared with the massless rod model, the proposed pose coupling model can significantly improve the control precision of the system. Compared with the separate control of position and attitude, the integrated control can not only avoid large attitude disturbance torque, but also reduce fuel consumption considerably.