DESIGN OF A GIMBALED COMPLIANT MECHANISM STAGE FOR PRECISION MOTION AND DYNAMIC CONTROL IN Z, θ_X θ_Y DIRECTIONS

摘要

Obtaining precise motion control of a compliant mechanism is often hindered by competing kinematic, mechanic and dynamic requirements. Resonances limit the control bandwidth while compliance requirements limit the mechanism's directional stiffness. This paper investigates the improvements possible for three-axis Z, θ_X & θ_Y diaphragm flexure stages through the use of a design (T-Flex) with members compliant in bending and torsion. According to analytical modeling and FEA, the T-Flex is capable of removing problematic resonant modes of vibration without significantly increasing the axial or tilt stiffness. Bench-level experimentation was conducted on various configurations of compliant mechanisms to determine their effects on the motion characteristics for precision engineering applications. The results indicate that by pairing the T-Flex with a radially stiff compliant mechanism, gimbaled motion can be achieved, providing 7.0 nm/μm lateral cross-axis (parasitic) motions. The mechanism exhibits linear axial and tilt stiffness of 0.195 N/μm and 5.37 x 10~(-6) N-m/μrad, respectively. Dynamic testing agreed with the FEA prediction of the first natural frequency to within 10%. The T-Flex coupled with the stiff radial flexure has the potential to provide a precise three-axis configuration with a fundamental resonant frequency of 600 Hz.