A real-time motion control strategy for redundant robots improving dynamics and accuracy

In this paper a new motion control strategy (FineMove) for manipulators with redundant serial kinematics is proposed, which is intended to improve the dynamics and accuracy of the TCP motion. The basic idea is to distinguish between groups of joints with low and high dynamics and to use the fast joints for the higher dynamic motion components. The FineMove algorithm works in real time and is demonstrated here by means of a partly sensor-guided control of the TCP motion. The paper describes the FineMove control strategy as well as its laboratory implementation, which is based on a seven degree of freedom robot with six revolute joints and a fast prismatic joint as the seventh axis. On the basis of experimental results the performance of FineMove is demonstrated. Furthermore the usability in an industrial application is shown by a robot based laser cutting process. Here accuracy and dynamics play a key role. For an excellent machining quality it is crucial to position the laser spot exactly on the surface of the work piece.