Singularity Analysis of a Novel 4-DOF Surgical Robot

This paper presents the singularity analysis of a novel endoscopic surgical parallel manipulator. The 4-DOF, 2- PUU_2-PUS, surgical robot design has larger bending angles and workspace volume. All previous manipulators have a zero pitch and infinity pitch reciprocal screws, so it is easy to find out the singular configurations inside the workspace. On the other hand, the novel 4-DOF surgical robot (2-PUU_2-PUS) has h-pitch reciprocal screws. The known geometrical approach for reciprocal-screws could not provide all singular configurations of the novel manipulator. Geometrical/Analytical approach for reciprocal-screws based singularity analysis of 2-PUU_2-PUS is proposed. The proposed algorithm can find all singular configurations of any limited DOF parallel manipulator with h-pitch reciprocal screws. The results show the feasibility of the proposed algorithm to find all singular configurations of the 4-DOF parallel manipulator. The discovered singularity configurations shrieked greatly the singularity free workspace to one fourth the original workspace. In order to be able to work through the entire workspace, we suggest changing the topology structure of the manipulator.