Optimizing fault tolerance to joint jam in the design of parallel robot manipulators

A methodology is developed to modify the kinematic layout of parallel manipulators to provide fault tolerance to active-joint jam at a large number of end-effector poses. The modification is based on equipping each branch of the manipulator with a redundant backup active joint to which the actuation is switched in case of a joint jam. An efficient optimization procedure based on linear algebra is developed to determine the optimum location and direction of each backup joint. The procedure is applied successfully on a 6-degree of freedom example manipulator.