Study on fault tolerant workspace and fault tolerant planning algorithm based on optimal initial position for two spatial coordinating manipulators

Fault tolerant motion planning of two spatial coordinating manipulators having two possible locked joints respectively is studied. First, the calculation method of fault tolerant workspace with respect to different joints is given, and the centrality index that measures the relative position between the trajectory of end-effector and fault tolerant workspace is formulated. Then based on this new index, the fault tolerant planning algorithm with optimal initial posture for the coordinating manipulation of two redundant manipulators is proposed. This algorithm can be used to perform a fault tolerant operation for two coordinating manipulators both at the moment of a failure and after a failure. Finally, the simulation researches for two spatial 4R manipulators demonstrate the validity of this proposed algorithm.