記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media {LLC}  

We propose miniature ultrasonic motors using stators made of a single bulk piezoelectric element. The bulk piezoelectric stator has the potential to increase output by reducing the dissipation that occurs in the adhesion layer between the PZTs and a metallic component in the stator. In this paper, we build two kinds of bulk piezoelectric stators: a cubic bulk stator with a side length of 4.2 mm and a hole of 3 mm in diameter, and a cylindrical bulk stator with an outer diameter of 4.2 mm and the same hole diameter. We evaluate their electrical and mechanical characteristics, such as impedance and vibration velocity. The experiments clarify the advantages of the bulk piezoelectric stators, such as low dissipation. The cubic bulk stator, which shows higher performance than the cylindrical one, is compared with a similar-shaped stator using a bronze cube and thin piezoelectric plates. The performance measures of the cubic bulk ultrasonic motor are optimized by the preload between the stator and rotor.

DOI： 10.1186/s40648-020-00179-w

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Institute of Electrical and Electronics Engineers ({IEEE})  

Micromotors are of great interest not only for the miniaturization of current products but also for the realization of future micromachines that can explore challenging environments. The speed of downsizing actuators is slower than that of semiconductor components, but developments over the last two decades have overcome several difficulties and enabled engineers to start designing applications. In this article, we review the existing micromotors ranging from famous articles to state-of-the-art, in particular recent developments and their applications. We deal with three representative principles for rotary and linear micromotors: electromagnetics, electrostatics, and piezoelectricity. Another purpose of this article is to suggest design criteria and physical limitations on these principles for engineers who design millimeter-scale automation devices. Incorporating micromotors can permit space saving and improve design flexibility in application designs, such as smartphones and medical devices.

DOI： 10.1109/ACCESS.2020.3041457

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Institute of Electrical and Electronics Engineers ({IEEE})  

We propose a miniature rotating mirror system using a micro-ultrasonic motor that employs a 45& x00B0; angle mirror as its rotor for enlarging the angle of view of cameras. The motor assy, measuring 2 mm in diameter and 4 mm in length, is one of the smallest motors and is expected for medical applications such as endoscopes. In this paper, we build a micromirror assembly, install it into a visual feedback system with an optical system, and demonstrate a motor control with a quick and wide angle-of-view observation. The high-speed camera vision embedded in the system measures the quick motion of the motor in real-time and enables accurate positioning of the mirror angle by p-control using burst waves. The proposed system demonstrates the visual feedback control of the miniature rotating mirror to the angle information obtained by the high-speed camera. The feasibility of the mirror system driven by the micro-ultrasonic motor is shown via demonstration.

DOI： 10.1109/ACCESS.2019.2957298

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

We propose a micro linear ultrasonic motor, which is one of the smallest linear actuators that can generate practical force. Such a small actuation mechanism can be used for a wide range of applications, such as auto-focus systems used in thinner cell phones and smaller endoscopes. In this paper, we design the micro linear ultrasonic motor and evaluate the performance of the prototype motor. The size of the prototype stator with piezoelectric elements measures 2.6 mm in height, 2.6 mm in width, and 2.2 mm in depth (the length in slider travel direction). There is a hole of 1.4 mm in diameter at the stator center, and the slider inserted into the hole moves back and forth when voltages are applied to the piezoelectric elements. By optimizing the preload between the stator and slider experimentally, the motor thrust force has been improved to over 10 mN, which is a practical force for moving small objects. Experiments clarify the output characteristics in response to the input voltages. Finally, a maximum thrust force of 20 mN has been obtained at applied voltages with an amplitude of 150 Vp-p. (C) 2018 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.sna.2018.05.022

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会議種別：口頭発表（一般）  

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