Design, Modeling, Testing, and Control of a Novel Fully Flexure-Based Displacement Reduction Mechanism Driven by Voice Coil Motor

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This paper presents a flexure-based displacement reduction mechanism driven by a voice coil motor to improve the motion resolution and eliminate the hysteresis nonlinearity of the traditional piezo-actuated micropositioning/nanopositioning stages. The mechanism is composed of three groups of compound bridge-type displacement reduction mechanisms, which adopt distributed-compliance rectangular beams to reduce the concentration of stress and improve the dynamic performance of the mechanism. The symmetrical distribution of the structure can eliminate the parasitic displacement of the mechanism and avoid the bending moment and lateral stress applied to the voice coil motor. Firstly, the analytical model of the mechanism is obtained by the stiffness matrix method. The theoretical displacement reduction ratio, input stiffness, and natural frequency of the displacement reduction mechanism are obtained by solving the analytical model. Then, through the static analysis and modal analysis of the mechanism with the Ansys software, the accuracy of the analytical model is verified, and the experimental prototype is also constructed for performance tests. The results show that the maximum stroke of the mechanism is 197.43 μm with motion resolution of 40 nm. The natural frequency is 291 Hz, and the input stiffness is 28.50 N/mm. Finally, the trajectory tracking experiment is carried out to verify the positioning performance of the mechanism. The experimental results show that the designed feedback controller has good stability, and the introduction of the feedforward controller and disturbance observer can greatly reduce the tracking errors.