Submicrometer overshoot control of rapid and precise positioning

Abstract

Precise-positioning technique is relatively well developed. However, it is still difficult to avoid an overshoot or to limit the overshoot within a submicrometer in a rapid and precise positioning. Inspired by recent studies on microdynamics, a control algorithm based on the variable structure control (VSC) method is proposed to achieve an overshoot smaller than 0.2 μm and rapid, precise positioning (a 0.5 mm ∼ 1 cm positioning with a steady-state error smaller than 30 nanometer in 0.5 s) with a linear motor drive stage. The stage is guided by a rolling ball guide and with a 10 nm resolution laser interferometer as its position sensor. Some characteristic values in the friction model of microdynamics are included to design the controller. Therefore, we found a way to achieve rapid, precise, and Small overshoot positioning by combining mechanism design system identification, lubrication, and controller design techniques.