A Multipoint Regulated Inchworm Rotary Piezoelectric Actuator Inspired by Hula Hoop Motion

Inspired by the hula hoop motion, a multipoint regulated inchworm rotary piezoelectric actuator (MR-IRPA) driven by the radial force was proposed, and the multipoint regulated driving principle was explained. The output angle model was established based on the kinematic analysis and the predeformation model of the rolling bearing. In the piezoelectric actuator field, the model revealed the effect of the rotor radial clearance and the contact deformation of rolling element group on the output angle for the first time, which provided a theoretical basis for the following design of the inchworm rotary piezoelectric actuators (IRPAs). In addition, the results proved that the steps per cycle were improved from one to six. When the rotor radial clearance is 11.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\mu}$</tex-math></inline-formula>m, the maximum stable angle speed of 0.25 rad/s was achieved for the MR-IRPA at the excitation frequency of 50 Hz and excitation voltage of 90 V. To ensure the operation reliability and safety, the optimal excitation parameters were given based on the analysis results of electromechanical conversion rate and thermal imaging. Finally, a laser ablation experiment system was established to verify the practicality of the proposed MR-IRPA.