Locked-joint failure identification for free-floating space robots

The space robot is concerned the most reasonable method for on-orbit servicing tasks. In space applications, failure of the manipulator is critical for both the space robot and the spacecraft serviced. The failure mode concerned in this paper is locked-joint failure which is one of the most common modes. To identify the locked position of the joint, the response mapping between of the joints motion and the base motion is derived based on momentum conservation theorem. Then, the base velocity can be computed with a reckoned value of the locked position. By revising the reckoned value, the error between the velocities calculated and measured can be decreased. The Differential Evolution (DE) algorithm is utilized to search the locked position. At last, the illustrative simulation shows that the failure identification method proposed in this paper is feasible and the identified result is accurate.