Kinematic control of a seven-joint manipulator with non-spherical wrist

This paper focuses on the real-time kinematic control of a seven-joint industrial robot manipulator having a nonspherical wrist. Despite the structure of the wrist, a two-stage inverse kinematics algorithm is devised which solves for the arm's inner five joints in the first stage and for the outer two joints in the second stage. A damped least-squares technique with varying damping factor is adopted to provide robustness to kinematic singularities. An additional constraint is introduced and a task priority strategy is adopted to solve redundancy. Experimental results are reported in a case study.