Lithographic apparatus and device manufacturing method

A lithographic apparatus comprising:

• a processing device to determine a feedforward transfer function of a control system, the processing device including instructions to:
• iteratively learn a first feedforward output signal of the control system using an iterative learning control for a first setpoint signal an a third feedforward output signal for a third setpoint signal;
• determine a feedforward transfer function from the first and third feedforward output signals and the first and third setpoint signals;
• use the feedforward transfer function to determine a second feedforward output signal for a second setpoint signal;
• and
• control movement of a stage using the second feedforward output signal, wherein the control system comprises a stage control system.

A method for manufacturing a device, comprising:

• patterning a beam of radiation with a patterning device;
• projecting the patterned beam of radiation onto a substrate;
• developing the substrate irradiated with the projected patterned beam of radiation;
• and
• manufacturing a device from the developed substrate,
• wherein at least one of the patterning device or the substrate is held by a stage, a position of the stage controlled by a control system including a feedforward transfer function, the feedforward transfer function determined by:
• iteratively learning a first feedforward output signal of the control system using an iterative learning control for a first setpoint signal and a third feedforward output signal for a third setpoint signal;
• determining a feedforward transfer function from the first and third feedforward output signals and the first and third setpoint signals;
• using the feedforward transfer function to determine a second feedforward output signal for a second setpoint signal;
• and
• controlling movement of the stage using the second feedforward output signal.