Analysis and Robust Control of an Precision Motion Platform using Disturbance Compensation

Abstract

This paper presents the utilization of a disturbance observer (DOB) with robust loop shaping filter to achieve robust stability in presence of significant plant uncertainty. Finite element analysis together with frequency response measurements are used to analyze position dependent plant uncertainty. Three different shaping filter are proposed including elliptic filter and an adaptive notch filter. The different concepts are implemented on a dual axis precision motion platform, which is actuated by direct-drive permanent magnet synchronous motors (PMSMs). Experimental validation is carried out to investigate the performance of the system. Using the proposed robust control, the angular precision is improved by a factor of 2.2 from 1.03 μrad to 0.46 μrad, and this level of precision is maintained over the entire positioning and velocity range.