Optimization of Failure-Tolerant Workspaces for Redundant Manipulators

For a redundant manipulator a region in its workspace that is guaranteed failure tolerant, called the failure tolerant workspace, promises completion of critical
tasks placed within it. By judiciously choosing a set of artificial joint limits which constrain the
acceptable robot configurations prior to a failure, a failuretolerant
workspace can possibly exist even for manipulators with a single degree of redundancy. This work identifies the candidate boundaries of failure-tolerant workspaces, and
presents justification on their validity and completeness. Based
on the identified boundaries, optimization results for a 3- degreeof-freedom
(dof) planar manipulator, as well as for a 4-dof planar manipulator, are presented. It assumed that the
manipulator has the ability to lock a joint that has failed, and that
the manipulator’s workspace degree of freedom remains the
same before and after a joint failure.