Analytical Inverse Kinematics and Self-Motion Application for 7-DOF Redundant Manipulator

This paper studies multiple inverse kinematics solutions for a 7-DOF human redundant manipulator with a special joint configuration. A method is proposed for determining the continuous joint angle vector by selecting the inverse solution from discrete multiple solutions to the continuous end path of the mechanical arm. The elbow angle constraint is introduced, and the mapping relationship from the elbow angle to the joint angle is established. Subspaces are found in the multiple solution spaces to avoid joints exceeding the limit to obtain elbow angle interval, and then combined with the collision detection technique, subspaces are sought in multiple solution spaces to avoid collisions between robotic arms and obstacles. Two subspaces are then obtained, and with use of their intersection, all feasible manipulator inverse kinematic solutions that avoid the joint limit and the obstacles at a given pose are obtained. The above method explicitly determines the complete feasible kinematic inverse solution of redundant manipulators. Finally, the validity of the methods is verified via kinematic simulations.