Coordinated motion control of multiple robotic devices for welding and redundancy coordination through constrained optimization in Cartesian space

The problem of coordinating a positioning table and a seven-axis manipulator is examined. The method described is based on subdivision of tasks. The welding table is coordinated to align the weld point surface normal antiparallel to the direction of gravity. The seven-axis robot (a six-axis Cybotech WV 15 robot and a track) is constrained to move the weld torch along the weld trajectory. The robot coordination is achieved by keeping the six-axis arm in good maneuverability position, i.e. far from its singular configurations and far from the motion limits of the six-axis arm and the track. The singularity configurations of the Cybotech WV 15 are expressed in terms of Cartesian coordinates. As a result, the redundancy coordination is expressed as an optimization of the maneuverability in Cartesian coordinates. An analytic solution to the optimization is found; it gives the Cartesian positions of the track and the robot end-effector. These positions are used to generate the joint angles of the arm by inverse kinematics