Measuring and reducing the Euclidean-space effects of robotic joint failures

Robotic joint failures are directly characterized and measured in joint spa ce. A locking failure, for example, is one for which a joint cannot move, a nd it gives an error equal to the desired value minus the locked value, Thi s article extends the joint-space characterization to Euclidean space by me asuring a failure's effect there. The approach is based on a rudimentary me asure of point error that can be defined to be distance or path length, It is used to form comprehensive measures through weighted integration over Eu clidean-space regions, For kinematically redundant manipulators, minimizing the measures using the redundancy is a method to induce failure tolerance. This can be applied both before a failure to reduce the likelihood of coll ision-induced damage and after a failure to reduce end-effector error. Exam ples for both cases are given.