Impact of amplifier errors on position loop accuracy of high-precision moving stages

To maximise essential system performance parameters, this research combines electrical, mechanical and position control models of a high-precision mechatronic system. The degradation of system performance induced by identified amplifier errors is analysed to reveal the significance of each error mechanism. The simplified outline of a mechatronic system is given to which models of the power amplifier are added in order to emulate the error mechanisms. Analysis of the impact of each error mechanism on the position accuracy of the mechatronic system is given from which specifications for the power amplifier can be obtained for a certain required position accuracy. Ensuing properly targeted requirements provide focused amplifier optimisation.

Introduction

Industrial applications using fast-moving high-precision stages, e.g. lithographic equipment (see Fig. 1 [1]), require power amplifiers with high-precision output current generation capabilities. Errors produced by the amplifier with respect to the current reference influence the stationary and dynamic positioning accuracy of a high-precision mechatronic system [2], [3]. Current research focuses on the improvement of the performance of high-precision amplifiers, e.g. [4], [5], and position control of high-precision stages, e.g. [1], [6], [7], independently. However, the influence of the performance of the amplifier on the position accuracy of the moving stage has not been analysed yet.