The tethered space robot (TSR) is a new\nconcept of space robot which consists of a robot platform,\nspace tether and operation robot. This paper presents a\nmulti-objective optimal trajectory planning and a\ncoordinated tracking control scheme for TSR based on\nvelocity impulse in the approaching phase. Both total\nvelocity impulse and flight time are included in this\noptimization. The non-dominated sorting genetic\nalgorithm is employed to obtain the optimal trajectory\nPareto solution using the TSR dynamic model and\noptimal trajectory planning model. The coordinated\ntracking control scheme utilizes optimal velocity impulse.\nFurthermore, the PID controller is designed in order to\ncompensate for the distance measurement errors. The PID\ncontrol force is optimized and distributed to thrusters\nand the space tether using a simulated annealing\nalgorithm. The attitude interferential torque of the space\ntether is compensated a using time-delay algorithm\nthrough reaction wheels. The simulation results show\nthat the multi-objective optimal trajectory planning\nmethod can reveal the relationships among flight time,\nfuel consumption, planar view angle and velocity\nimpulse number. This method can provide a series of\noptimal trajectory according to a number of special tasks.\nThe coordinated control scheme can significantly save\nthruster fuel for tracking the optimal trajectory, restrain\nthe attitude interferential torque produced by space\ntether and maintain the relative attitude stability of the\noperation robot.
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