Piezoelectric inchworm rotary actuator with high driving torque and self-locking ability

One major obstacle to the development of a piezoelectrically-driven actuator with a large motion range is the requirement to provide a high load capacity and a reliable self-locking capability simultaneously for most applications. In this work, a piezo-driven rotary actuator with a simple and compact structure is designed based on the inchworm principle to realize long-range rotary motion. High driving torque with a self-locking capability at rest is achieved by integral design of the overall structure, in which the distributions and stiffness values of the flexure hinges are carefully designed. A prototype was fabricated and the working performance of the device was tested. The test results demonstrate that the driving torque of the prototype is more than 245 Nmm, with self-locking torque of more than 882 Nmm. In addition, the maximum rotary speed is 26.74 mrad/s at a driving frequency of 180 Hz, and a minimum step rotary angle of 4.79 μrad is obtained at a step driving voltage of 10 V.