Design and modeling of a compliant tip-tilt-piston micropositioning stage with a large rotation range

Abstract

In compliant tip-tilt-piston micropositioning stages, it is difficult to achieve a large rotation range using small air–gap voice coil actuators. With a smaller air gap, the voice coil actuators can produce a larger output force; however, the coil of the voice coil actuator touches the stator as the stage rotates. This paper presents the mechanical design, modeling and experimental tests of a novel large-angle tip-tilt-piston stage driven using four small air-gap voice coil actuators. In order to prevent the occurrence of undesired contact between the coil and stator, a compliant decoupling mechanism is introduced to minimize the transverse displacement of the coil of the voice coil actuator. An improved substructure method based on the compliance matrix is applied to calculate the rotational stiffness of the stage and transverse displacement of the coil. Lagrange’s equation is used to obtain the dynamic resonant frequencies. Based on this, an optimization procedure is proposed for determining the design parameters of the stage. The finite element analysis is performed to verify the theoretical calculation. Finally, a prototype of the stage is fabricated, and experiments are conducted to validate the feasibility of the stage. The proposed stage can achieve rotational–motion strokes of 83.18 mrad and 82.26 mrad in the working axes, for which the rotational mode frequencies are 55.45 Hz and 56.09 Hz, respectively. The motion resolution of the stage is ±6.67 μrad. The maximum transverse displacement of the coil of the voice coil actuator is 10.98 µm, which is negligible as compared to the air gap (0.38 mm) of the voice coil actuator. In summary, a tip-tilt-piston stage was designed to achieve a large rotation range using small-air-gap voice coil actuators.

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