| 20120019801 | POSITION CONTROL SYSTEM, LITHOGRAPHIC APPARATUS, AND METHOD TO CONTROL A POSITION OF A MOVABLE OBJECT - A position control system to control the position of a movable object, including a position measurement system configured to determine an actual position related quantity of the movable object; a set-point generator to provide a position related set-point signal of the movable object; a comparator 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 to provide a control signal on the basis of the error signal, a feed-forward device to provide a feed-forward signal on the basis of the position related set-point signal, and one or more actuators to act on the movable object on the basis of the control signal and the feed-forward signal, wherein the feed-forward device includes a disturbance force correction table including estimations of disturbance forces exerted on the movable object in dependence of a position of the movable object. | 01-26-2012 |
