Patent ID: 8135488
Filing Date: 2012-03-13
Classification: G03F,G16Z

Abstract:
1. A controller for use in a positioning device, the controller constructed and arranged to: receive a position signal indicative of a position of the positioning device; compare the position signal to a set-point signal indicative of a desired position of the positioning device to obtain an error signal; selectively modify the error signal based on an amplitude and a frequency content of the error signal to obtain a modified error signal; and generate a control signal to control the positioning device based on the modified error signal, wherein the controller is constructed and arranged to, in order to selectively modify the error signal, (a) perform a first frequency based filtering of the error signal to obtain a filtered error signal; (b) perform an amplitude based modification of the filtered error signal; and (c) perform a second frequency based filtering substantially corresponding to an inverse of the first frequency based filtering.