Stage system and lithographic apparatus comprising such stage system

A stage system for a lithographic apparatus includes a stage, an over-determined number of actuators to act on the stage, at least two sensors to measure a position dependent parameter of the stage and to provide a respective sensor signal. The at least two sensors are arranged to measure the respective position dependent parameters in a same degree of freedom. A controller is provided to provide a controller output signal to at least one of the actuators in response to a setpoint and the position dependent parameter as measured by at least one of the sensors. A further controller is provided with the position dependent parameters measured by the sensors. The further controller is configured to determine a difference between the position dependent parameters from the sensors and to provide a further controller output signal to at least one of the actuators in response to the determined difference.