On the Sudden Change in Joint Velocity during Fault Tolerant Operations for Spatial Coordinating Redundant Manipulators

When one joint of a manipulator fails and is locked, the velocities of remaining joints will produce sudden change. The sudden change of joint velocity in fault tolerant operation of two coordinating manipulators for locked joint failures is studied. First, the difference between the joint velocity of original manipulator and that of reduced manipulator is defined as the sudden change in joint velocity. Then, a corresponding fault tolerant planning algorithm based on this index is proposed. At last, numerical and solid simulations of fault tolerant operations for two spatial 4R manipulators are implemented. Simulation results show that the initial postures of the two manipulators heavily affect the sudden change in joint velocity. The algorithm proposed in this paper can decide the optimal posture with minimum sudden change in joint velocity, strengthen manipulators´ motion stability and so improve their kinematical and dynamic properties in fault tolerant operations