Yuichiro Kume

Vibrotactile letter reading using a low-resolution tactor array

Vibrotactile displays have been studied for several decades in the context of sensory substitution. Recently, a number of vibrotactile displays have been developed to extend sensory modalities in virtual reality. Some of these target the whole body as the stimulation region, but existing systems are only designed for discrete stimulation points at specific parts of the body. However, since human tactile sensation has more resolution, a higher density might be required in factor alignment in order to realize general-purpose vibrotactile displays. One problem with this approach is that it might result in an impractically high number of required tactors. Our current focus is to explore ways of simplifying the system while maintaining an acceptable level of expressive ability. As a first step, we chose a well-studied task: tactile letter reading. We examined the possibility of distinguishing alphanumeric letters by using only a 3-by-3 array of vibrating motors on the back of a chair. The tactors are driven sequentially in the same sequence as if someone were tracing the letter on the chairs back. The results showed 87% successful letter recognition in some cases, which was close to the results in previous research with much larger arrays.

Foot interface: fantastic phantom slipper

just as freely in a virtual environment as they do in the real world. Wearable interfaces should not cause psychological and/or physical discomforts. This slipper-like multi-modal interface is based on those two assumptions. It features a slipper interface with cyberworlds. Each foot’s movement is measured in real time with an optical motion capture system, and feedback signals are transmitted to the soles. Phantom sensations elicited by multiple tactile stimuli allow transmission of complicated feedback information such as objects moving around the feet. Optical markers for motion capture and vibrators for tactile stimulation are installed in the slippers. Players interact with virtual objects projected onto a floor screen, sense them, and use them to play games. The system runs on a single PC.

Investigation of basic imaging properties in digital radiography. 10. Structure mottle of II–TV digital imaging systems

Single-frame images obtained with image intensifier (II)-TV digital systems contain a large amount of structure mottle. In the present study, we examined several II-TV digital systems by use of Wiener spectral analysis and noted considerable variation of the structure mottle over the wide spatial frequency range. We found that the structure mottle in these systems may originate in the input phosphor, the output phosphor, and/or the electronic components, and that the Wiener spectra of structure mottle seem to depend on the specific combination of these components. The results of observer performance studies indicated that structure mottle can significantly decrease the detection of low-contrast objects in a single-frame image when the exposure incident on the II is greater than approximately 0.1 mR. In addition, we showed that the structure mottle can be removed by subtraction of a uniformly exposed mask. This simple procedure will improve the quality of radiologic images obtained with II-TV digital systems. Note, however, that the structure mottle is largely eliminated by subtraction in digital subtraction angiography (DSA) images.

A Solid-State Electrochemical Device Using Poly(pyrrole) as Micro-actuator

A solid-state microactuator was studied using volume change due to redox reaction of poly(pyrrole) film. Pyrrole was electropolymerized on a comb-shaped microelectrode array, and the poly(pyrrole) film was covered by a solid polymer electrolyte, polyethylene glycol. The volume change of the poly(pyrrole) film by electrochemical polarization was measured using a laser displacement sensor, and the mechanism of the volume change was discussed.

Towards Effective Information Display Using Vibrotactile Apparent Motion

In this paper, we explore the use of tactile apparent motion at different speeds for information display. A prototype vibrotactile tactor array was constructed, consisting of three rings of five voice-coil tactors each, and mounted on the upper arm of test subjects. The results of two experiments are presented: a study on the sensitivity to differences in apparent motion speed, and a study on users’ ability to differentiate four motion patterns at three different speeds. Users had little trouble with pattern identification, but found absolute speed recognition difficult. Several ideas for future exploration of tactile apparent motion for general-purpose information displays are presented.

Investigation of basic imaging properties in digital radiography. 11. Multiple slit‐beam imaging technique with image intensifier–TV digital system

We are developing a digital x-ray imaging system using a multiple slit assembly (MSA) and an image intensifier (II)-TV digital system. The advantage of this approach is that the scatter from an object and the veiling glare in the II-TV system can be reduced significantly while the x-ray utilization is maintained much better than that with a single slit-beam technique. The quality of reconstructed images is related to many parameters such as the slit width, the lead spacer, the number of image frames, and the reconstruction algorithm. In this study, reduction of scatter and veiling glare was measured quantitatively, and image artifacts were analyzed. It was found that the fraction of scatter and veiling glare can be reduced to approximately 0.01-0.1 by use of the MSA imaging technique, and that the magnitude of the fractions is strongly dependent upon the slit width and the lead spacer of the MSA used. The artifacts are caused by inaccuracies in the slit width, lead spacer, and scan motion, and by undersampling of image data. The overlap scanning technique was effective in reducing the magnitude of these artifacts in the reconstructed image.

Color influences on human beings evaluated by nasal skin temperature

Since colors affect human beings both physiologically and mentally, various studies have been conducted about the infl uences of color. Most of the studies have been focused on the psychological aspects. In this study, we investigated the infl uences of color physiologically by the use of infrared thermography. With this technique, the subjects wear no devices, and objective values are expected to be obtained to evaluate the infl uences of color. Nasal skin temperatures were measured by infrared thermography under yellow, red, and blue illuminations. A significant temperature change was observed under red illumination.

Incoherent pattern detection using a liquid-crystal active lens

Incoherent pattern detection by a simple imaging system using a liquid-crystal active lens is proposed. The imaging system works as a spatial filtering system with a rewritable phase-only filter. We found that, in the incoherent matched filtering system, a conventional phase-only filter has a higher optical efficiency but a lower pattern discrimination than a complex filter. To improve the pattern discrimination ability, we optimized the phase-only filter by using simulated annealing and a genetic algorithm. We designed phase-only filters that have discrimination ability comparable with that in a complex filter. The performance of optimized phase-only filters is experimentally demonstrated.

A Hand-held Display Presenting Visual and Force Information

A hand-held display presenting visual and force information is proposed. The display is constructed with an LCD panel and a moving weight. The forces applied to users both hands holding the display are changed with the movement of the weight set on the backside of the display. The weight is moved by a PC-controlled servo-motor. With the prototyped display, the force perception affected by the weight movement was psychophysically measured as a fundamental property. The users feel the force changes to the hands, sufficiently

Improvement of spatial resolution properties of image intensifier–TV digital systems with a multiple‐narrow‐slit beam imaging technique

Multiple-slit beam imaging technique with an image intensifier (II)-TV digital system has been developed to remove scatter and veiling glare while high x-ray beam utilization is maintained. Although the contrast and signal-to-noise ratio (SNR) are improved with this technique, the overall image quality obtainable with an II-TV digital system is still limited due to low spatial resolution, which is mainly caused by the large pixel size, i.e., by the small matrix size used. In order to overcome the limitation of the pixel size, we have developed a new method of improving the resolution properties of the II-TV digital system by use of a multiple-slit assembly (MSA) having a narrow slit width. When the slit width of the MSA is narrower than the pixel size of the II-TV digital system, two signals from a given slit due to different MSA placements may be detected by the same pixel in different image frames, and the detected signals of the slit images are mapped to a large matrix. In this way, the spatial resolution in the direction perpendicular to the slit openings can be improved along with the increased contrast and SNR as the scatter and veiling glare can be removed. Experimental results are presented, and the effect of an anisotropic resolution property on the overall image quality is discussed.