A fast control law for nano-positioning

To achieve fast nano-positioning control in a large traveling distance with a single motion stage and without a waiting time, this paper presents a micro-dynamic model together with a simple switching rule and two controllers, one for macro-dynamics and the other for micro-dynamics, such that the moving stage can smoothly travel from macro-dynamic range into micro-dynamic range. First, a microdynamic model is proposed to capture the complicated hysteresis behavior of the nonlinear micro-dynamics. Next, two controllers of simple structures are designed for the micro-dynamic traveling range and the macro-dynamic traveling range, respectively, based on the previous model. Finally, a simple switching law is proposed to complete a design. Experiments show that the resultant control system has a fast response speed without a sluggish response in the conjunction of the macro-dynamic range and the micro-dynamic range. Furthermore, it can sustain large disturbances while holding the motion stage at the set point. (c) 2006 Elsevier Ltd. All rights reserved.