MAGNETICALLY LEVITATED PRECISION STAGE FOR XYZ SAMPLE POSITIONING IN X-RAY MICROSCOPES

抄録

Micro/nano-positioning stages are at the core of a wide range of machines and instruments such as lithography scanners, precision machine tools, and microscopes. Growing demand for precise positioning performance over long motion strokes in all translational degrees-of-freedom (DOFs) necessitates innovation in the design and development of precision motion solutions. In this paper, we present the modeling, designing, prototyping, and experimental evaluation for a magnetically levitated micropositioning stage which is capable of high-speed, long-stroke precision motion in all translational DOFs. The proposed stage presents a novel magnetic design with a stator which generates uniform homopolar magnetic fields across large air gaps of approximately 20 mm and actuator coils arranged on the motion stage to allow for active control of the stage’s levitation and motion via Lorentz forces. Such a magnetic design enables a uniform force generation on the stage over a long motion stroke. Uniform force generation enables linear plant dynamics, which is critical to achieve high positioning performance. The maximum force of the stage is 25.5 N under 3.5 A current amplitude, which generates a stage acceleration of 3.5G. The prototype stage has been successfully levitated, and the stage position control loop has a bandwidth of 50 Hz. These results show that the proposed stage is able to meet the acceleration requirement for microscope applications, and show promise for achieving the required positioning accuracy and motion stroke with upgraded position sensors of long measurement range and nanometer accuracy.