High precision eddy current damped electromagnetic positioner with flexure-suspension

This paper proposes a novel high precision planar electromagnetic-actuated positioning stage. The movable part of the stage is suspended by a monolithic parallel flexure mechanism, which motion comes from the deformation of the structure itself. A linear electromagnetic actuator which consists of a near-uniform magnetic field and four coils is designed and implementation to provide the propelling force for translational and rotational motions. An eddy current damper is designed and integrated with the electromagnetic actuator to suppress the vibration of the flexure, whose non-contact property is more advanced than the contact damper used in our previous researches. The design traveling range is 3 mm times 3 mm in planar motion. A 3-axis laser interferometer measurement system is utilized to feedback the position and posture information of the moving stage. The experimental results show the vibration of the flexure mechanism could be suppressed by the designed eddy current damper. The results also show the regulation and tracking performance by a well-designed robust adaptive sliding mode controller, which can overcome the disturbance and modeling uncertainty and guarantee a satisfactory performance.