Faculty Profiles - Mashimo Tomoaki

Papers - Mashimo Tomoaki

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Experimental Verification of Elliptical Motion Model in Travelling Wave Ultrasonic Motors Reviewed

T. Mashimo, K. Terashima

IEEE/ASME Transactions on Mechatronics 20 ( 6 ) 2699 - 2707 2015

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

We propose a model of a traveling wave ultrasonic motor that includes the elliptical motion amplitudes of the stator and verify this model experimentally using a high-speed camera with a high-power lens (i.e., a high-speed microscope). This approach makes it easy to estimate the motor characteristics, such as the rotational speed and torque. In this paper, we build a mechanical model of the stator and rotor that incorporates the elliptical motion amplitudes. The elliptical motion of a few microns at ultrasonic frequencies is captured and measured by the high-speed microscope. When modeling parameters are determined from the observed vibration amplitudes, the model can predict the motor characteristics. We study how the observed elliptical motion is related to the motor output by varying the frequency of applied voltages, and verify the proposed model by comparison with the experimental results.

DOI： 10.1109/TMECH.2015.2392126

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Singularity-Based Four-Bar Linkage Mechanism for Impulsive Torque With High Energy Efficiency Reviewed

T. Mashimo, T. Urakubo, T. Kanade

ASME Journal of Mechanisms and Robotics 7 ( 3 ) 2015

Language：English Publishing type：Research paper (scientific journal) Publisher：ASME

We propose a mechanism that exploits the singular configuration in a closed-loop four-bar linkage that can produce a high impulsive torque (a high torque for a short period in time) at the start of motion and high angular velocity during the successive motion. Such characteristics make the mechanism suitable for executing with high energy efficiency a certain class of tasks, such as lifting heavy objects. In this paper, we define the singularity-based linkage mechanism (SLM), analyze its characteristics of torque generation and energy efficiency theoretically, and then confirm them experimentally by using an SLM prototype. The performance of the SLM is compared with that of a comparable size parallelogram mechanism (PM). It is shown that the energy efficiency of the SLM comes from the fact that it achieves the high acceleration of the output link in the neighborhood of the singular configuration by providing energy with low current and high voltage to the motor; whereas the typical PM requires high current to produce the comparable impulsive torque.

DOI： 10.1115/1.4028930

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Micro ultrasonic motor using a one cubic millimeter stator Reviewed

Tomoaki Mashimo

SENSORS AND ACTUATORS A-PHYSICAL 213 102 - 107 2014.7

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE SA

Ultrasonic motors are expected to be used as micro-actuators, and the miniaturization of these devices is an interesting subject. We present a micro ultrasonic motor using a stator with a volume of approximately 1 mm(3), which is one of the smallest ultrasonic motors. The stator consists of a metallic cube with a through-hole and piezoelectric elements adhered to its sides; the simplicity of the stator allows it to be miniaturized without special machining processes. The vibration mode that the stator generates for rotation is three waves around the circumference of the hole. This vibration mode can generate certain vibration amplitudes and driving torques even when the stator is miniaturized. In this paper, we build a prototype micro ultrasonic motor and examine its basic characteristics, including impedances and vibration amplitudes. The basic motor performance, such as its torque and rotational speed, is demonstrated experimentally. (C) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.sna.2014.03.018

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Piezoelectric Rotational Mixer Based on a First Bending Vibration Mode Reviewed

Tomoaki Mashimo

IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL 60 ( 10 ) 2098 - 2104 2013.10

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

We propose a miniature piezoelectric mixer that can rotate a liquid inside a hole of several millimeters diameter. The mixer has dimensions 14 x 14 x 10 mm with a through-hole (7 mm), and piezoelectric elements bonded to its four identical sides. When the first bending vibration mode of the mixer is excited by ac voltages, rotational flow of liquid is generated by the rotation of an acoustic field (acoustic streaming) in the through-hole. This technology is useful in automating mixing processes such as the mixing by hand of a few drops of blood in medical testing. In this paper, we verify the driving principle experimentally and examine the characteristics of a prototype mixer, including the induced flow velocity, under changes of the amplitude and frequency of the applied voltages. A plastic test tube, used to prevent contamination, is inserted to the through-hole, and the liquid inside the tube is mixed by rotation of the acoustic field.

DOI： 10.1109/TUFFC.2013.2800

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Spherical ultrasonic motor drive system for camera orientation in pipe inspection Reviewed

Masahiko Hoshina, Tomoaki Mashimo, Naoki Fukaya, Osamu Matsubara, Shigeki Toyama

ADVANCED ROBOTICS 27 ( 3 ) 199 - 209 2013.2

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

We propose a camera actuating system using a spherical ultrasonic motor for inspection of the inside wall of a small pipe. The spherical ultrasonic motor has advantages that include three degrees of freedom, high responsiveness and high accuracy all within a compact body. We describe here the development of an outer rotor spherical ultrasonic motor (OR-SUSM) that enables a camera to rotate by more than 360 degrees along the side of the pipe. All components, including the OR-SUSM, the sensing system, and the electric circuits, are designed to be assembled in the pipe inspection device with outer diameter of 52mm. To control the system, the phase difference and frequency of the applied voltages are used. The rotational direction is determined by the phase difference and the angular velocity is controlled by the frequency. The completed system can be controlled to within 2 degrees in an experimental pipe inspection test.

DOI： 10.1080/01691864.2012.754077

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Vibration Analysis of Cubic Rotary-Linear Piezoelectric Actuator Reviewed

Tomoaki Mashimo, Shigeki Toyama

IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL 58 ( 4 ) 844 - 848 2011.4

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Cubic design of a stator in a rotary-linear piezoelectric actuator is sophisticated and interesting, but the vibration theory of the cubic stator remains unclear when using the finite element method (FEM). In this paper, we analyze the vibration behavior of the cubic stator by applying the energy method, which distinguishes the component of mechanical energy. By changing the design of the stator (especially the length in the direction of the through-hole axis), we clarify how the vibration modes are in accordance at one equal frequency in cubic shape. The behavior of the vibration modes is discussed using conventional vibration theory of a beam and a plate.

DOI： 10.1109/TUFFC.2011.1877

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Rotary-Linear Piezoelectric Microactuator With a Cubic Stator of Side Length 3.5 mm Reviewed

Tomoaki Mashimo, Shigeki Toyama

IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL 57 ( 8 ) 1825 - 1830 2010.8

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

We report a miniature rotary-linear piezoelectric actuator with a single cubic stator of side length 3.5 mm which can generate rotary motion around the center axis and linear motion in the axial direction. The stator is fabricated as a single metallic cube of side length 3.5 mm with a 2.5-mm-diameter through-hole and four piezoelectric elements bonded to the sides of the stator. The simplicity makes the actuator compact without any special manufacturing. In the design for miniaturization, the modal analysis using the finite element method indicates the natural frequency of the stator from the side length 14 mm to 3.5 mm. In the experiments, rotary motion of 24 rad/s and 2.5 mu Nm were obtained at a resonant frequency of 280 kHz, and linear motion of 80 mm/s and 2.6 mN was observed at 305 kHz by driving the system at an applied voltage of 42 V(rms).

DOI： 10.1109/TUFFC.2010.1621

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Development of spherical ultrasonic motor as a camera actuator for pipe inspection robot

Masahiko Hoshina, Tomoaki Mashimo, Shigeki Toyama

2009 IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2009 2379 - 2384 2009.12

Language：English Publishing type：Research paper (international conference proceedings)

We present a pipe inspection robot using a newly developed spherical ultrasonic motor (SUSM) as a camera actuator. The novel SUSM has improved the range of movement compared to previous SUSMs, and the robot can point a camera in any direction. In this study, we determined a method for controlling the rotational direction and strategic control from the kinematics and characteristics of ultrasonic motors. The rotational directions were defined by the phase differences of the applied voltages, and the rotational speeds were changed with the frequencies. Additionally, we developed a very small position sensing system using rotary potentiometers. In the control experiment performed using the sensing system, the SUSM showed the returnability to the default position from several specified points, within an accuracy of 1°. © 2009 IEEE.

DOI： 10.1109/IROS.2009.5354315

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Design and Implementation of a Spherical Ultrasonic Motor Reviewed

T. Mashimo, S. Toyama, H. Ishida

IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 56 ( 11 ) 2514 - 2521 2009

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

We present a mechanical design and implementation of spherical ultrasonic motor (SUSM) that is an actuator with multiple rotational degrees of freedom (multi-DOF). The motor is constructed of 3 annular stators and a spherical rotor and is much smaller and simpler than conventional multi-DOF mechanisms such as gimbals using servomotors. We designed a novel SUSM using experimental data from a single annular stator and a finite element method. The SUSM using a spherical rotor of diameter 20 mm without any reduction gear has demonstrated advantages of high responsiveness, good accuracy, and high torque at low speed. The dynamic implementation of SUSM was consistent with the driving model of SUSM based on a friction drive.

DOI： 10.1109/TUFFC.2009.1338

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単一ステータによる回転直動圧電アクチュエータの開発(第2報)−TRモータの特性− Reviewed

真下智昭, 遠山茂樹

精密工学会誌 2009

Rotary-Linear Piezoelectric Actuator using a Single Stator Reviewed

T. Mashimo, S. Toyama

IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 2009

Development of micro ultrasonic motor for surgery Reviewed

S. Toyama, T. Mashimo

Journal of Vibroengineering 11 ( 1 ) 27 - 33 2009

Language：English Publishing type：Research paper (scientific journal) Publisher：JOURNAL VIBROENGINEERING

We present a micro ultrasonic motor having rotary and linear motions for endovascular diagnosis and surgery. The stator prototype is a cube of side 3.5mm, and the main body is fabricated as a single metallic cube with a through-hole at the center. Four piezoelectric elements are bonded to the sides of the stator. When AC voltage is applied to the piezoelectric elements, the circumference of the stator generates elliptical motions. We can obtain the Output from a shaft inserted through the hole. We developed the first prototype of the stator, and determined the rotary-linear motion.

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球面超音波モータを用いたMRI環境下手術支援マニピュレータの開発（第2報）−光ファイバを用いた姿勢センシングの開発− Reviewed

真下智昭, 粟賀宏介, 遠山茂樹

精密工学会誌 74 ( 4 ) 400 - 404 2008

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society for Precision Engineering

We present theoretical and experimental analyses of an optical attitude sensing system for an MRI-compatible surgical assist manipulator using a spherical ultrasonic motor. In the system, a laser light passes through an optical fiber to a flat mirror of a spherical rotor; the reflection from the mirror is caught by optical fibers. The observed light intensity is converted to attitude information by a neural network, and the rotation of the spherical rotor is detected. The system uses optical fibers and allows the spherical rotor to be miniaturized and inexpensive. In this report, we developed the optical attitude sensing system and tested the drive of spherical ultrasonic motor with the sensing system. As the result, the attitude sensing resolution was less than 0.5°. The sensing system has indicated the feasibility for the control of the manipulator.

DOI： 10.2493/jjspe.74.400

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Other Link： https://jlc.jst.go.jp/DN/JALC/00354777894?from=CiNii

超音波を用いた血栓吸引カテーテルの開発 Reviewed

高見沢悟, 真下智昭, 遠山茂樹

ライフサポート学会誌 18 74 - 74 2008

単一ステータによる回転直動圧電アクチュエータの開発(第1報)−駆動原理と有限要素法を用いたステータの設計− Reviewed

真下智昭, 遠山茂樹

精密工学会誌 2008

球面超音波モータを用いたMRI環境下手術支援マニピュレータの開発（第1報）−MRI対応球面超音波モータの試作− Reviewed

真下智昭, 遠山茂樹, 石田寛

精密工学会誌 73 ( 2 ) 275 - 280 2007

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society for Precision Engineering

In this paper we report the development of a novel actuator for surgical assist manipulator to perform minimally invasive surgery with magnetic resonance imaging (MRI) guidance. The actuator, which is called the spherical ultrasonic motor (SUSM), is constructed of a spherical rotor and three ring-type stators, and has multi-degrees of freedom. In this study, the principle of the SUSM is described. A novel SUSM composed of non-magnetic materials has been constructed, the stator of which was designed using the finite element method. Evaluation of the driving characteristics revealed the SUSM to have good responsiveness and high positioning accuracy. In MRI environment, the noise effects of the SUSM on MRI images were examined. The results demonstrate the feasibility of the surgical assist manipulator using the SUSM.

DOI： 10.2493/jjspe.73.275

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Other Link： https://jlc.jst.go.jp/DN/JALC/00342235320?from=CiNii

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