2つの共振駆動モードと1つの非共振駆動モードを有する超音波モータの開発

概要

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In this study, a new design of an ultrasonic motor to expand the controllable driving speed range is proposed. Two piezoelectric elements are bonded to the metal elastic body with the cross angle of 90°. When one of the piezoelectric element vibrates at resonance frequency of elastic body, the contact point of between the motor and the carriage moves elliptically and the driving force is generated. The driving direction conversion can be easily performed by switching the piezoelectric elements. The motor have three drive modes. In the first mode (= a high-speed driving mode), the elliptical motion is provided by degenerating the resonance vibrations in X and Y directions of the metal-elastic body. In the second mode (= a low-speed driving mode), a combination of X-direction resonance vibration and piezoelectric elements original vibration is used. In the third mode (= a fine motion mode), small expansions of the piezoelectric elements with stick-slip motion are used. In this research, these three modes are combined to attain the wide range of the driving speed. As a result, the driving speed range from 10 to 500mm/s is obtained by adjusting the driving voltage and driving frequency. In the paper the principle, the design and experimental results are discussed.