Studies on stepping characteristics of traveling-wave ultrasonic motor

This paper presents analysis on speed regulation and stepping characteristics of Shinsei USR60 ring-type traveling-wave ultrasonic motors (USM) based on experimental results, and discusses the influence of controlling method and load variation on stepping control. From the experiments the relationship between the variables is revealed, and improvements to the stepping control are proposed. The improvement focuses on correcting the stepping angle deviation with an empirical equation obtained by performing the least square curve fitting on the results from the USM characterizing experiments. The improved controller is able to perform equal distance stepping when the ring-type traveling-wave USM is operating with loads. The proposed stepping control method is capable of realize open-loop positioning control of ring-type traveling-wave USM without position sensors with precision reaching 0.005°.