Compact Traveling Wave Micromotor Based on Shear Electromechanical Coupling

Abstract

A compact traveling wave piezoelectric micromotor is proposed based on ${d_{15}}$ shear electromechanical coupling. A single bulk lead zirconate titanate is employed as the stator, which offers a comparatively small length-to-width ratio. The system construction is simplified and favorable for further miniaturization. The wobbling motion of stator generates traveling waves on the surface when the first- or second-order bending mode is stimulated by a rotating electric field, and thus to move the rotor with friction in clockwise or counterclockwise directions. The vibration property is analyzed in detail and design optimization is conducted. A research prototype with a size of 0.75 mm $\times$ 0.75 mm $\times$ 1.55 mm has been developed and an experimental rig with adjustable payload is built up for the performance test. Experimental result proves that the proposed motor can work in wide frequency bands of more than 10 kHz for both the first- and second-order bending modes. The system can achieve no-load speed of 1850 r/min and maximum torque of at least 2 $\mu$ N $\cdot$ m at no more than 60 ${{\rm {V}}_{{\rm {pp}}}}$ , which is very competitive compared to other micromotors. The developed piezoelectric micromotor has potential applications in small-sized systems such as micromedical robots, etc.