Design and Modeling of a Piezoelectric, Bistable Out-of-Plane Actuator for Micro-Robotic Appendages

This paper explores the design and modeling of a bistable, piezoelectrically-actuated mechanism intended to produce out-of-plane rotation of micro-robotic appendages. The design is based on thin-film lead-zirconate-titanate (PZT) unimorph bending beams with mismatched lengths that connect a silicon appendage to a substrate or chassis. Device modeling focuses on the relative effects of internal piezoelectric bending moments versus residual stress from fabrication processes, across various candidate actuator dimensions. Analytical modeling indicates that beam arrays using the bistable design can improve on range-of-motion and stiffness of similarly-sized but linear bending beam arrays. Preliminary validation of the design is performed using a larger, centimeter-scale mock-up, while observations from prototype micro-scale fabrication are noted, along with implications for process control necessary to successfully implement the design in a terrestrial micro-robot.