Smooth robot motion with an Optimal Redundancy Resolution for PR2 robot based on an analytic inverse kinematic solution

Current support for the PR2 humanoid arm motion planning does not provide a redundancy resolution scheme and this can cause excessive movements and discontinuities in the generated trajectories. We provide an innovative solution and implementation in ROS that can be used to deliver smooth motions that people find to be intuitive and easy to predict. This paper, provides a comprehensive analysis of kinematics of the PR2 humanoid robot arm including an analytic Inverse Kinematics solution and an Optimal Redundancy Resolution scheme. First, a closed form IK computation method is introduced for the PR2 arms providing all feasible solutions in global jointspace for a given value of the first joint angle as a redundant parameter. Then, a redundancy optimization technique is customized and formulated based on a desired objective function that finds optimal values for the redundant parameter. The proposed technique computes robot motion plan more effectively so that the robot behaviors are expected to be more reliable. The technique has been implemented successfully on PR2 for a hand writing task.