Achieving High Rotary Motion Consistency Based on the Novel Internal-Gear-Mechanism-Inspired Rolling Driving Principle (RDP) With a Single PZT

The rotary stick-slip actuators typically employ the asymmetric driving principle to achieve stick-slip motion, resulting in an inconsistent bidirectional driving process and posing challenges for achieving high rotary motion consistency with a single PZT. The current approaches involve multiple sets of driving structures to achieve high consistency but bring a complex system with multi-PZTs and need complex adjustment procedures for symmetrical assembly. This work presents a novel rolling driving principle (RDP) to ensure an identical bidirectional driving process and achieve single-PZT actuated high rotary motion consistency, owing to the RDP’s symmetrical circular structure and tangential contact condition. Moreover, its tangential contact condition enhances the adaptive capability to the assembly errors. An RDP-type rotary stick-slip actuator is proposed based on the newly designed isosceles trapezoidal flexible mechanism (ITFM). The axial drift of the ITFM flexure is modeled and the design optimization is conducted to determine the ITFM’s optimal structural parameters. Experiments have been carried out to verify the prototyped actuator’s performance at both high and low frequencies. The results demonstrate the RDP-type actuator’s excellent bidirectional motion consistency, with speed difference ratios of 1.47% at 10 Hz and 7.57% at 320 Hz, and angular resolution differences of 2.06% (0.97 μrad and 0.95 μrad) for a 20 mm rotor diameter.