Patent ID: 8825182
Filing Date: 2014-09-02
Classification: G03F

Abstract:
1. A position control system to control a position related quantity of a movable object, the position control system comprising: a position measurement system configured to determine an actual position related quantity of the movable object; a set-point generator configured to provide a position related set-point signal of the movable object; a comparator configured to provide an error signal on the basis of a comparison of the actual position related quantity and the position related set-point signal; a controller configured to provide a control signal on the basis of the error signal; a feed-forward device configured to provide a feed-forward signal on the basis of the position related set-point signal, said feed-forward signal to be combined with said control signal using an addition device; and an actuator configured to act on the movable object on the basis of the control signal and the feed-forward signal, wherein the feed-forward device comprises a disturbance force correction table comprising estimations of disturbance forces exerted on the movable object in dependence of a position of the movable object, said feed-forward device providing said feed-forward signal using said disturbance force correction table.