Bipedal driven inertial type piezoelectric motor working under quasi-static and resonant states

An inertia piezoelectric motor based on bipedal driven, which can work in not only quasi-static but also resonant states, is proposed, designed, fabricated and studied considering the high resolution of quasi-static piezoelectric motor and the high speed of resonant piezoelectric motor. The two stators of the piezoelectric motor are drived by two sinusoidal electrical signals with 1:2 frequency ratio to generate sinusoidal vibration on the corresponding driving foot. A continuous step motion without frequency limitation is realised under the action of inertia and friction forces after synthesising the sinusoidal vibration of different frequencies into mechanical sawtooth vibration. The natural resonant frequencies of the piezoelectric motor are adjusted to a specific proportion to combine the vibrations in the resonant state through finite element analysis. In the structure of two stators, each stator has a corresponding inertia block, and the corresponding resonant frequency can be altered by adjusting the mass of the inertial block without affecting the other resonant frequency, thus markedly simplifying the design difficulty of the piezoelectric motor which can work in quasi-static and resonant states. The motion characteristics of the prototype are tested by building the prototype and experimental platform. Experimental results show that the maximum speed of the prototype is 29.3 mm s⁻¹ and the maximum load is 2 N in the resonant state, the minimum displacement resolution of prototype motor is 0.26 μm in the quasi-static state. The motion characteristics of the prototype are consistent with the theoretical analysis, which provides an effective idea to improve the comprehensive performance of the piezoelectric motor.