Abstract: A pair of complementary magnetic actuators controls a stage in a high-precision positioning instrument in a single coordinate direction. Additional pairs of complementary magnetic actuators can be used to provide control of the stage in other coordinate directions. A small current through the windings of both magnetic actuators provides a zero net force on the fine stage, thus maintaining the position of the fine stage. The small current used to control the fine stage minimizes the RMS power gain. By increasing the current in one magnetic actuator while decreasing the current in the other, a net force is generated for large accelerations of the stage. Control of the magnetic actuators is simplified by simultaneously increasing and decreasing the current through the windings of the complementary magnetic actuators prior to accelerating the stage. Additionally, a feedforward command can control the magnetic actuators to decrease the settling time of the system.

Abstract: A fine stage control system for use for instance in a semiconductor lithography machine, uses a pair of opposing (push-pull) E/I core actuators to move the stage with high precision along an axis. The paired actuators are coupled together mathematically in terms of their control characteristics and controlled as a single entity, thereby providing a more efficient control scheme and improved system performance.