Force analysis and hybrid control scheme for multiple robot manipulators

Coordination control for multiple robot manipulators is investigated. The controlled variables, i.e., the external and internal arm forces, are first defined, based on the decomposition of the robot arm force, and then a hybrid control scheme at the robot end-effector level is proposed. The control scheme consists of three loops: (i) an external force loop, which enables the robot manipulators to induce the desired object dynamics and contact force between the object and the environment, (ii) an internal force loop, which makes the manipulators impose the desired internal force on the object, and (iii) a robot motion loop which controls the robot arms to track the desired trajectories. A criterion related to the load capability of the robot arm is presented for distributing a load among the manipulators. An integrated control system for two industrial robots is developed.