Coordination of two redundant robots

The authors present a solution to the optimal force distributions for two redundant coordinating robots. Two coordinating robots whose end-effectors firmly grasp a common inertial load form a closed-chain structure. In these closed kinematic chains, the two robots must observe a set of constraint conditions on the end-effectors´ positions, orientations, linear and angular velocities and the forces and torques inserted onto the end-effectors by the load. To achieve the maximum load capability, the optimal force distribution under the known posture is developed. If both robots are redundant, joint solutions may be obtained if some optimization criterion such as manipulability is imposed. The singularity, manipulability, and force ellipsoid are investigated for the two coordinating redundant robots in terms of the two manipulator Jacobian matrices. The manipulability is shown to correspond to the cascade structure while the force ellipsoid corresponds to the parallel structure in terms of their manipulator Jacobian matrices. Null-space contributions towards singularity escapement and mechanical advantage are found