Structure design and trajectory planning of a precision repetitive-scanning stage with separated drive units for heat-reduction

Precision repetitive-scanning stages which exist in lithographic reticle system, scanning probe microscope, etc, have been widely used in modern precision industry. In such stages, the accelerated and constant-speed motions are both driven by the same motor, where heat generation becomes a potential obstacle for achieving high performance. Considering the motion characteristics of such stages, it would leads to a heat-reduction nature if the accelerated and constant-speed motions are driven by two separated drive units (SDUs). Inspired by this thought, we design a novel precision repetitive-scanning stage specially equipped with a separated permanent-magnetic drive unit for accelerated motion. In order to achieve the desired motion function with the effect of SDUs, a modified repetitive-scanning trajectory is proposed. For this trajectory, a parametric model with simple calculation procedure is significantly provided to match the permanent magnetic drive force, which results in a sufficient utilization of the SDUs´ drive ability. Finally, a precision repetitive-scanning stage prototype system is set up. Comparative experimental results demonstrate that the proposed scheme can effectively achieve a desired high motion accuracy and, more importantly, can significantly reduce the heat generation in practical repetitive-scanning motion.