Tracking and Structural Vibration Control of Flexible Ball–Screw Drives With Dynamic Variations

This paper proposes a parallel structure of a feedback controller for the ball-screw drive systems which have significant dynamic variations during operations. The controller consists of two controllers with two different objectives. One controller aims at moving the workpiece table so that its position tracks reference trajectories with high speed and high accuracy. The other controller is for suppressing the structural vibration caused by the cutting force disturbance around system´s resonant frequencies. To take into account the resonant modes´ variations which are peculiar to ball-screw drives, a gain-scheduled controller is utilized as the vibration suppression controller. Advantages of the proposed controller structure in the ball-screw drive control application are discussed. It is experimentally demonstrated that the controller with the parallel structure is effective in achieving high performance in both trajectory tracking and cutting force disturbance rejection.