Patent ID: 7468782

Claim:
A lithographic apparatus comprising: a first movable element and a first control system to control a first position quantity of the first movable element; a second movable element and a second control system to control a second position quantity of the second movable element; a feedforward table comprising feedforward table data and configured to be used to generate a feedforward signal in synchronism with a setpoint signal to be provided to the first and second control systems, wherein the feedforward table is configured to provide the feedforward signal to the first control system to adapt the first position quantity so as to reduce a relative error between the first and second position quantities; an error table configured to register a tracking error between the position quantities of the first and second movable elements in response to the setpoint signals provided to the first and second control systems; and a processing unit to derive a next feedforward table data from the registered tracking error and the feedforward table data.