Design, modeling, and test of a normal-stressed electromagnetic actuated compliant nano-positioning stage

This paper presents the design, modeling, and test of a novel normal-stressed electromagnetic (NSEA) compliant nano-positioning stage. The stage has a concise structure, which makes it compact and easy to assemble. With the consideration of the coupling interaction between the electromagnetic and mechanical components, an electromagnetic–mechanical modeling method for NSEA compliant nano-positioning stages is introduced. The direct relationship between the input current and the output displacement is derived in the static model, and the potential energy resulting from the magnetic field is considered in the dynamic model. Therefore, the working stroke and natural frequency of the NSEA compliant nano-positioning stage can be accurately predicted. A prototype with a stroke of 132.2μm and a natural frequency of 683.8 Hz is fabricated. Experimental results demonstrate that the proposed electromagnetic–mechanical modeling method has significantly higher prediction accuracy over the previous methods. A feedforward–feedback controller is designed, which enables a −3 dB control bandwidth of 145% of the open-loop natural frequency and a nanometer level motion resolution. A RMS tracking error of 0.45% is achieved for a 10 Hz triangular motion with ±50μm amplitude.