Direct and inverse kinematics for coordinated motion tasks of a two-manipulator system

A new formulation for direct kinematics of a system of two manipulators is presented. This allows a straightforward description of general coordinated motion tasks in terms of meaningful absolute and relative variables. An effective inverse kinematics algorithm is devised which exploits the above formulation where the task Jacobians are expressed in terms of the Jacobians of the single manipulators. The scheme is extended to handle the presence of redundant degrees of freedom in the system. Different types of grasp between the end effectors and a commonly held object are treated with minimum reformulation effort. Case studies are developed throughout the paper for a system of two PUMA 560 manipulators which illustrate the capabilities of the scheme.