High-speed and high-precision table positioning system by using mode switching control

This paper presents a mode switching control-based point-to-point position control algorithm for fast response and high precision table drives. The system is basically a proportional position controller with a feedforward compensator and, in the vicinity of target position, the proportional control is switched to the proportional and integral control to satisfy the specified positioning characteristics. Since the dynamic characteristics after mode switching mainly depend on the motor velocity at the switching, the initial velocity should be optimally selected to realize the desired settling time and accuracy of positioning and this can be done by adjusting a coefficient of the feedforward compensator. The coefficient can be determined by a fuzzy inference-based approach to compensate the system uncertainties. The experimental studies using a table drive system of actual machine tools verify the effectiveness of the proposed drive.