A Motion Control Strategy for Robots in Laser Material Processing and other High Speed Applications

Laser-robots are well-established in the material processing industry. They are used for cutting, welding and marking of work pieces made from diverse materials. In these applications it is important to move the focal spot of the laser beam exactly along the desired machining contour on the work piece. Available laser sources are powerful enough to allow for very high machining velocities, which, however, are often beyond the capabilities of the robot arm that guides the laser beam. Due to their mechanical inertia, robot arms can not perform abrupt changes of velocity (direction and magnitude) even though this is frequently required in machining operations. In this paper a new motion control strategy (FineMove) is proposed, which is intended to partly overcome the dynamic limitations of robot arms with serial kinematics and six or more degrees of freedom. The paper describes the FineMove control strategy as well as its laboratory implementation, which is based on a rapid control prototyping system and a real time interface to a standard robot controller. Simulation-based and experimental results are presented and the performance of the control strategy in various test scenarios is described.