Patent ID: 8373849

Claim:
A lithographic apparatus comprising: a support constructed to support a patterning device, the patterning device being capable of imparting a radiation beam with a pattern in its cross-section to form a patterned radiation beam; a substrate table constructed to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate; and a positioning system configured to position a movable object, the positioning system comprising an actuator configured to apply a force to the moveable object; a sensor configured to measure a position quantity of the moveable object; and a control system configured to provide a drive signal to the actuator, the control system comprising a set-point generator configured to provide a reference signal; a subtractor configured to provide an error signal, the error signal being a difference between the reference signal and a signal provided by the sensor; and a control unit configured to provide the drive signal to the actuator in dependency of the error signal, wherein the control unit comprises a nonlinear controller configured to improve a low-frequency disturbance suppression and a compensator configured to at least partially compensate a deterioration of a high-frequency behavior of the control system caused by the nonlinear controller, wherein the nonlinear controller is configured to improve the low-frequency disturbance suppression based on an output of the compensator.