STUDY AND RESOLUTION OF SINGULARITIES FOR A 6-DOF PUMA MANIPULATOR

Upon solving the inverse kinematics problem of robot manipulators, the inherent singularity problem should always be considered, When a mani pulator is approaching a singular configuration, a certain degree of f reedom will be lost such that there are no feasible solutions of the m anipulator to move into this singular direction, In this paper, the si ngularities of a 6-DOF PUMA manipulator are analyzed in detail and all the corresponding singular directions in task space are clearly ident ified, In order to resolve this singularity problem, an approach denot ed Singularity Isolation Plus Compact QP (SICQP) method is proposed, T he SICQP method decomposes the work space into achievable and unachiev able (i.e., singular) directions. Then, the exactness in the singular directions are released such that extra redundancy is provided to the achievable directions. Finally, the Compact QP method is applied to ma intain the exactness in the achievable directions, and to minimize the tracking errors in the singular directions under the condition that f easible joint solutions must be obtained. In the end, some simulation results for PUMA manipulator are given to demonstrate the effectivenes s of the SICQP method.