Abstract: A lithographic apparatus includes a movable object and a control system to control the position of the movable object. The control system includes a position measurement system configured to measure the position of the movable object, a comparative unit configured to generate a servo error signal by subtracting a position signal representative of an actual position of the movable object from a reference signal, a control unit configured to generate a first control signal based on the servo error signal, a feed-forward unit configured to generate a feed-forward signal based on the reference signal, an addition unit configured to generate a second control signal by adding the first control signal and the feed-forward signal, and an actuator unit configured to actuate the movable object. A gain of the feed-forward unit is dependent on the position of the movable object.

Abstract: In a method for controlling a positioning device, the positioning device has a stator and mover, the mover being movable relative to the stator; a position sensor configured to generate a position signal indicative of a position of the mover relative to the stator; a controller configured to receive the position signal, compare it to a setpoint signal to obtain an error signal, and generate a mover control signal on the basis of a signal component of the position signal, the controller having a variable gain. The positioning device, including the position sensor and the controller, defines a control loop. For error signals having a magnitude in a predefined range, the gain is selectively set to a value higher than a value for error signals having a magnitude outside the range.

Abstract: A lithographic apparatus includes a movable part and a controller to control a position quantity of the movable part. The controller includes a first controller transfer function and a second controller transfer function. A selector selects the first controller transfer function or the second controller transfer function depending on a state of the movable part. The first controller transfer function may be chosen in a substantially stationary state of the movable part, while in a substantially non-stationary state of the movable part, the second controller transfer function may be chosen.

Abstract: A lithographic apparatus includes an illumination system for conditioning a radiation beam. A support structure supports a patterning device, which is capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam. A substrate table holds a substrate. A projection system projects the patterned radiation beam onto a target portion of the substrate. A motion control system includes a controller having a transfer function. The controller controls a position of the support structure and or the substrate table along a series of positions. The transfer function consists of a sum of a plurality of positional transfer functions, each determined in one of the positions, and each multiplied by a weighing function.