Design of a Flexure-Based XYZ Micropositioner With Active Compensation of Vertical Crosstalk

This paper presents the design and development of a new flexure-based XYZ micropositioner with a hybrid kinematic configuration. A piezoelectric-driven Z stage is embedded into a parallel-kinematic XY stage actuated by two voice coil motors. The XYZ micropositioner features a sizeable workspace with a compact architecture, which benefits from employing deployable mechanisms and mixed actuators. One uniqueness is that the Z-axis crosstalk error of the XYZ micropositioner is compensated by the closed-loop motion control of the Z stage, which achieves a constant vertical position of the center platform when performing planar motion tasks. Analytical models have been derived based on fixed-guided beam theory to assess the driving stiffness of the mechanism. The finite element analysis is carried out to verify the accuracy of the derived models. A prototype system of the XYZ micropositioner is fabricated with the dimension of 116 mm x 116 mm x 45 mm (i.e., 216 mm x 216 mm x 45 mm with actuators). Experimental results indicate that it obtains a workspace of 4.15 mm x 4.06 mm x 0.04 mm with a crosstalk of less than 1% among the three axes. With the active control of the Z-axis position, the vertical crosstalk error has been dramatically reduced from 7.333 to 1.719 mu m. The proposed design provides a promising approach to enable pure planar motion for ultrahigh precision applications requiring optical or electron focusing, such as electron beam lithography.

Automated summary

This paper presents the design and development of a new flexure-based XYZ micropositioner with a hybrid kinematic configuration. The XYZ micropositioner features a sizable workspace with a compact architecture, and its Z-axis crosstalk error is compensated by closed-loop motion control. Experimental results show reduced vertical crosstalk error and a promising approach for ultrahigh precision applications.