著者
星 貴之
雑誌
情報処理学会論文誌 (ISSN:18827764)
巻号頁・発行日
vol.57, no.12, pp.2589-2598, 2016-12-15

音響浮揚は強力な超音波を発生させる装置が必要であることから,これまで研究所など限られた場所でのみ行われていた.本研究では,一般人にも購入可能な材料を用いた音響浮揚装置の実現を目指す.前報において,市販の超音波実験キットの駆動回路をそのまま使用し,超音波振動子を球面に配列することによって,ポリスチレン粒子を浮揚できることを示した.本報では,3Dプリンタを用いて作製した安定な球面アレイと,それを用いて実現された浮揚現象とのインタラクションについて報告する.
著者
星 貴之
出版者
特定非営利活動法人 日本バーチャルリアリティ学会
雑誌
日本バーチャルリアリティ学会論文誌 (ISSN:1344011X)
巻号頁・発行日
vol.22, no.3, pp.293-300, 2017 (Released:2017-09-30)
参考文献数
13

The author is working on an ultrasonic device that produces tactile sensation in midair by focusing ultrasound. The high-intensity ultrasound at the focal point presses the skin surface. Although ultrasound itself is inaudible, audible noise is radiated when the focal point moves around. This noise is not desired for a tactile display because the noise makes the experience worse. This drawback has been found and reported in previous work, however no solution has been provided. This paper discusses the source of this noise and proposes a method to reduce it. The phase discontinuity of driving signals occurs when the focal point moves to the next position, and that leads to the sudden change of amplitude of ultrasonic waves. This sudden change of amplitude is the source of the noise. There are two ways to reduce this noise: One is making the original and target focal positions close and the other is changing the phase gradually. The former is effective only when the frame rate is high. Therefore we explore the latter. The behavior of the focal point during the phase shift is studied by simulation. An algorithm is developed and implemented into the current prototype device. The experimental results show the effectiveness of the proposed method.
著者
星 貴之
雑誌
エンタテインメントコンピューティングシンポジウム2015論文集
巻号頁・発行日
vol.2015, pp.100-106, 2015-09-18

音響浮揚は強力な超音波を発生させる装置が必要であることから,これまで研究所など限られた場所でのみ行われていた.本研究では,一般人にも購入可能な材料を用いた音響浮揚装置の実現を目指す.前報において,市販の超音波実験キットの駆動回路をそのまま使用し,超音波振動子を球面に配列することによって,ポリスチレン粒子を浮揚できることを示した.本報では,3D プリンタを用いて作製した球面アレイについて報告する.
著者
河野 通就 星 貴之 筧 康明
雑誌
エンタテインメントコンピューティングシンポジウム2013論文集
巻号頁・発行日
vol.2013, pp.41-46, 2013-09-27

本研究では,素材に対して外的な刺激や力を与えることにより,その素材特有の「生き物」のような振る舞いを抽出・表現することを目的としている.今回,筆者らは,音響浮揚によって粒状の物質を浮遊させ,あたかも小さなムシのように実世界の三次元空間上を移動させることを可能にし,さらに空中の粒子と人間との身体的なインタラクションを実現する.本稿では,コンセプト,システムの詳細,および実装したインタラクションについて報告する.
著者
星 貴之 早田 滋
出版者
公益社団法人 計測自動制御学会
雑誌
計測自動制御学会論文集 (ISSN:04534654)
巻号頁・発行日
vol.52, no.10, pp.518-523, 2016 (Released:2016-10-25)
参考文献数
9

Bonding machines suffer from a problem that a wavering disturbance of air occurs due to heaters and decreases the accuracy of vision sensing for tool positioning. Previous solutions use airflow to clear out heated air from the light path or physical/airflow walls to separate heated air from background air. Although these previous solutions have been in practical use, they have some drawbacks. Airflows reduce the bondability on the chip surface and have negative effects on the generation of FAB (free air ball) at the tip of wires. Physical walls convey heat to cameras and cause their thermal expansion, and the structure of the physical walls may vibrate due to the rapid motion of the other machine components. In order to avoid these drawbacks, we propose a new method that keeps the light path calm using ultrasonic standing wave. The incident ultrasonic wave travels vertical to the light path, and is reflected by a reflection wall. These incident and reflected ultrasonic waves make a standing wave which has a periodic structure of nodes and antinodes. The fluctuation of air is suppressed in this stable structure. To evaluate the performance of the proposed method, experiments were conducted. We took two parameters in the experiments. One was the distance between the light path (observation point) and the reflection wall. The other was the ultrasonic output. The experimental results showed that an antinode of sound pressure of the ultrasonic standing wave was the best part to suppress the fluctuation of the air and moderate ultrasound output was more effective.
著者
星 貴之
出版者
公益社団法人 計測自動制御学会
雑誌
計測自動制御学会論文集 (ISSN:04534654)
巻号頁・発行日
vol.50, no.7, pp.543-552, 2014 (Released:2014-08-02)
参考文献数
19
被引用文献数
1 1

Our research group has worked on an ultrasound-based noncontact tactile display. It utilizes a nonlinear effect of ultrasound to produce a force in midair. It is known that an object in the ultrasound field suffers a force (acoustic radiation pressure) in the direction of the ultrasound propagation. The position of the force is controlled three-dimensionally based on the phased array focusing technique: A focal point of ultrasound is generated by setting the phases of hundreds of ultrasound transducers adequately. After the presentations and the demonstrations of this tactile display, it gradually came out that some researchers working on research fields other than tactile display liked to use this device for their own issues. But the previous prototype device had a bulky body and complicated wires, and so it took time and labor to carry, setup, and install it. These drawbacks limited the situations in which it could be used and prevented us from giving it a try to use it in other application areas. In order to break through this difficulty, we newly developed a compact device which generates a noncontact force up to 16mN. It was carried out by integrating driving circuits and cutting out the expandability of the device. This small-sized and light-weighted device is easy to use and so useful for exploring new application areas. In this paper, firstly, the principles of the device are explained. Secondly, the design concept and the specifications of the device are provided. Thirdly, the experiments show that the ultrasound is focused as the theory predicted, the intensity of the output force is surely controlled by PWM, and the frequency characteristics covers up to 1kHz. Finally, the collaborative researches based on the developed ultrasound device are reported as the evidence of application exploration.
著者
落合 陽一 大山 剛史 星 貴之 暦本 純一
出版者
特定非営利活動法人 日本バーチャルリアリティ学会
雑誌
日本バーチャルリアリティ学会論文誌 (ISSN:1344011X)
巻号頁・発行日
vol.18, no.3, pp.277-286, 2013

A transparent screen is demanded in various applications. Our proposition is to use a membrane of colloidal liquid. We developed an ultra-thin and flexible BRDF screen, which is soap film exposed to ultrasound. The transparency of the film is controlled by ultrasound so that it modifies projected images to be realistic, distinctive, and vivid. A multi-layered 3D screen is developed by placing the multiple films and changing their transparencies alternately and adequately. The film also can be deformed by higher-amplitude ultrasound. The proposed screen contributes to the real world as the first prototype of a new concept of programmable screen.