A micro monolithic integrated force-torque sensor with piezoelectric tuning mechanism

Abstract

A novel micro force-torque sensor with tuning mechanism is presented in this paper. The sensor is designed and fabricated based on monolithic integrated method, including planar graphic manufacturing and lamination process. The sensing element is composed of cross-shaped double cantilever beams which will deform when loading force and Torque. The process of sensor is divided into two parts. The structure-circuit integration process is proposed to realize the planar structure of sensor, which integrates flexible printed circuit (FPC) in the graphic multi-layer materials. The assembly of force-torque sensor is realized by the design of foldable mirror structure with each component connected by flexible limited hinges, which can form and lock at 90°. By bring in piezoelectric (PZT) composite cantilever beams as tuning mechanism, the position of the sensor can be further tuned, so that the system precision can be significant improved. According to the result of calibration and experiments, the sensor prototype has a force sensitivity of 0.29 μm/mN, a torque sensitivity of 0.33 μm/μNm and a bandwidth of 481.44 Hz, the range of force and torque measurement is – 7~7 mN and – 14~14 μNm respectively. And the linear-adjustment sensitivity of PZT composite cantilever beam is 24.69 nm/V.