Identification and super-precision control of a linear stage driven by a voice coil motor

Abstract

Identification and control of an air bearing linear stage driven by a voice coil motor are considered. The load of the stage is more than 5 kg, and the model has to include the mode of mechanism for high bandwidth and high precision motion control. Identification based on normalized coprime factors is introduced for this purpose. A precise model with high order can be derived from the identification, but the order of the model is too high to control design, therefore, model reduction is performed. Finally, a polynomial pole-placement combined with sensitivity function shaping is carried out. The experimental result shows the stage can achieve 10 nm position step easily.