Kei Nakatsuma

Active bioacoustic measurement for human-to-human skin contact area detection

This paper describes a method to acquire the human-to-human skin contact area quantitatively. Touch is humans fundamental communication and is reckoned to have positive effects physically and emotionally. Indeed, physical stimulation is applied for clinical treatments for mental disorders. However, there is no existing technique to quantitatively measure the amount of touch (area, position, time length, etc.). Our method employs an active bioacoustics measurement technique to quantify the skin-to-skin contact area. A proposed system consists of a vibration unit and a sensing unit. A couple of users wear the units respectively. When they touch with each other, acoustic (elastic) waves propagate through their bodies via the skin contact zone. We consider that the amplitude of the waves which reach the sensing unit depends on the contact zone area. A result of our fundamental experiment supports our expectation.

Temperature Variation Compensation Using Correlation in Pressure Change Leakage Tests

The conventional pressure change method used in leakage tests is sensitive to the ambient temperature variation. We propose a new method using a correlation technique to compensate for temperature variation in pressure change leakage detection. In the proposed method, gas within a vessel is compressed in such a sequence that it shows no correlation with the ambient temperature variation. The extent of leakage is estimated from the correlation between the pressure variation in the vessel and the compression sequence signal. Experimental results showed that leakage can be successfully detected by the proposed method without being affected by temperature variation.

Flexible ultrasonic transducers by automatic spray coating for non-destructive testing

Development of flexible ultrasonic transducers for non-destructive testing (NDT) application has been desired since many infrastructures were consist of complex geometry. Sol-gel spray technique realized flexible ultrasonic transducers, however, it is difficult for manual spray coating to make quality assurance. In addition, manual spray coating is not suitable for mass production. Therefore, automatic spray coating method is desired for flexible ultrasonic transducer fabrication.

Evaluation of kerfless phased array using sol-gel composite spraying technique

We have developed a kerfless phased array transducer using sol-gel composite spraying technique. This technique is a method for developing piezoelectric transducer by spraying composite material of piezoelectric sol-gel solution and powder, and it has attracted great attention especially in non-destructive testing over the years because of its features such as curved surface suitability, flexibility, and high-temperature durability. The porosity can contribute to a decrease in crosstalk among elements. As a preliminary experiment, a kerfless linear array transducer with a center frequency of 5 MHz and pitch of 500e-6 m using the sol-gel composite spraying technique was fabricated and fundamental performance was evaluated. As a result, approximately -130 dB of crosstalk was obtained.

Detection of ultrasound pressure distribution for remote measurement of haptic surface roughness

This paper proposes a new remote measurement method of surface roughness for haptic applications. In our method, measurement object surface is irradiated with a coherent ultrasound from a remote point. A spatial sound pressure distribution that is formed by reflected waves varies depending on the surface geometry. We can evaluate the surface profile by measuring the sound pressure distribution. We conducted fundamental experiments and could show the effectiveness of our manner.

Haptic-emoticon: a framework for creating and sharing haptic contents

Haptics is a complex sensation with pressure, temperature, vibration, and so on. Therefore developing an interface for creating or designing haptic contents is an attractive challenge. One solution is reduction and simplification of the haptic information. For example, Minamizawa et al. have simplified it as a temporal signal (sound) in TECHTILE toolkit [1]. We have inspired from handwriting motion on a skin. Our solution is a reduction to spatiotemporal information and we employ a spatiotemporal stroking trajectory on a 2D surface for a haptic content.