Design and Characterization of a Planar Motor Drive Platform Based on Piezoelectric Hemispherical Shell Resonators

Frank Schiele,Bernd Gundelsweiler

doi:10.3390/act10080187

Abstract

In this study, a planar ultrasonic motor platform is presented that uses three half-side excited piezoelectric hemispherical shell resonators. To understand the working principle and the harmonic vibration behavior of the piezoelectric resonator, the trajectory of the friction contact was measured in free-oscillating mode at varying excitation frequencies and voltages. The driving performance of the platform was characterized with transport loads up to 5 kg that also serve as an influencing downforce for the friction motor. The working range for various transport loads and electrical voltages up to 30 V is presented. Undesirable noise and parasitic oscillations occur above the detected excitation voltage ranges, depending on the downforce. Therefore, minimum and maximum values of the excitation voltage are reported, in which the propulsion force and the speed of the planar motor can be adjusted, and noiseless motion applies. The multidimensional driving capacity of the platform is demonstrated in two orthogonal axes and one rotary axis in open-loop driving mode, by measuring forces and velocities to confirm its suitability as a planar motor concept. The maximum measured propulsion force of the motor was 7 N with a transport load of 5 kg, and its maximum measured velocity was 77 mm/s with a transport load of 3 kg.

Highlights

Ultrasonic motors of the standing wave type use resonators made of piezoelectric ceramic materials to create propulsion force via a friction contact
In the event that ultrasonic motor technology is requested for such a planar motor, either a perpendicular setup of plate resonators—as in [11,12]—is conceivable, or the resonator geometry must be changed to a type allowing multidimensional vibrations
An innovative ultrasonic motor was presented that allows motion in both the translatory and rotary directions on a single stage as a planar motor platform, by standing and moving on three ruby friction contacts

Summary

Introduction

Ultrasonic motors of the standing wave type use resonators made of piezoelectric ceramic materials to create propulsion force via a friction contact. The friction contact pushes at ultrasonic resonance frequency against a movable rotor or a guided slider element, and sets these in motion [1,2,3]. Available standing wave motors typically use plate geometry for their resonators [4], since this geometry is very suitable for strong linear forward and backward motion along one axis. In the event that ultrasonic motor technology is requested for such a planar motor, either a perpendicular setup of plate resonators—as in [11,12]—is conceivable, or the resonator geometry must be changed to a type allowing multidimensional vibrations. Various concepts for composite multidimensional resonators in planar motors can be found in research publications, such as those mentioned in [13,14,15]

Methods

Results

Conclusion