Implementation and displacement self-sensing of a 4-DOF piezoelectric micromanipulator

Abstract

This paper reports the development and displacement self-sensing of a new four degrees-of-freedom (DOF) piezoelectric micromanipulator. In particular, each micromanipulator arm can move along the clamping and vertical directions, constructing with two degrees of freedom, and two micromanipulator arms exhibit four degrees of freedom. Thus, it improves operational flexibility. Meanwhile, the self-sensing method avoids additional external sensors when detecting output displacements. The piezoelectric micromanipulator is devised based on the transverse inverse piezoelectric effect of two sets of vertical spatial crossings. Static and dynamic characteristics are analyzed via finite element optimization of geometric parameters. Then, a displacement self-sensing method based on charge integration is proposed. This method measures the generated charge on the clamping arm surface from the piezoelectric wafer deformation under the driving voltage. A self-sensing circuit is designed to obtain the surface charge of the clamping arm. Then, several experiments are conducted to test the micromanipulator. The maximum displacements of the designed micromanipulator are about 66.29 μm and 63.09 μm along clamping and vertical directions. Moreover, output displacements, response time, and inherent frequencies obtained based on the self-sensing method agree well with those with laser sensors. In addition, an operation application for micro-shaft assembly is presented, demonstrating the grasping and docking operations of the micro-shaft in the clamping and vertical directions.