Time-Optimal Trajectory Generation and Contouring Control for Machine Tool Feed Drive Systems

Time-optimal trajectory planning for mechanical systems has been widely studied thus far because of its effectiveness to reduce the time required for many industrial tasks. However, in general, because the time-optimal trajectory is generated based on ideal dynamics of controlled systems, it may be difficult to implement the obtained trajectory to actual systems with vibration modes that are neglected in the trajectory generation. In other words, high-speed motion based on the time-optimal trajectory may cause the vibration of mechanical systems. We propose to employ the contouring control, which enables to reduce controller gain magnitudes while contouring performance are maintained, for the implementation of the optimal trajectory. First, this paper presents a method of generating the time-optimal trajectory for machine tool feed drive systems. Next, the contouring controller is applied to implement the optimal trajectory to the actual machine tool system. The effectiveness of the contouring controller for implementation of the optimal trajectory is demonstrated by comparative experiments with the conventional method.