A Precise Rotary Piezoelectric Actuator Based on the Spatial Screw Compliant Mechanism

Rotary piezoelectric actuators (RPAs) are widely used in various precise applications. But given the rotary axis offset caused by the single off-center driving force or the discrepancy of multiple piezoelectric elements, most previous works present rotary roundness loss. Besides, there is a contradiction between the motion range of RPA and its response speed. For solving these problems, an RPA based on the spatial screw compliant mechanism (SSCM) is hereby proposed; a theoretical model and an finite element (FE) model are built to verify the actuation principle and guide the structural design; and a prototype is fabricated and tested. The experimental results indicate that the static rotary angle changes from 0 to 4.935 mrad as the voltage changes from 0 to 100 V with a high resolution of 45.53 nrad. The first resonant and -3 dB cutoff frequencies are measured as 1361.5 and 2040.1 Hz, respectively. With the application of the SSCM, the RPA is proven capable of avoiding the rotary roundness loss in theory, and it can balance the milliradian-level rotary range with millisecond-level response speed driving by one lead zirconium titanate (PZT) stack under a small size of Φ32 × 68 mm2.