Masataka Niwa

Determining appropriate parameters to elicit linear and circular apparent motion using vibrotactile cues

This paper reports on two experiments we conducted to look at how to design effective linear and circular apparent-motion displays. Using a two-tactor array on the upper arm, the first study found that a time interval of greater than 400ms before repeating the directional sequence is required for subjects to achieve 95 % proficiency of direction identification over a range of Duration of Stimulus (DOS) and Stimulus Onset Asynchrony (SOA) values. The second study looked at the number of tactors necessary in a circular tactor array on the upper arm for people to correctly identify the direction of the rotation. We found that subjects could achieve a proficiency approaching 100 % across a large range of DOS and SOA values with four tactors, using a circuit-completion time of 400ms or longer. These findings can be used by interface designers to realize information displays that either stand on their own, or work in combination with visual and/or audio displays.

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.

A closed-loop tactor frequency control system for vibrotactile feedback

In this paper, we address the problem of maintaining a precise frequency in vibrating motors for use as vibrotactile cueing devices. Our solution utilizes a piezoelectric film sensor that measures the motor frequency and uses a feedback-loop circuit to dynamically adjust the motor power to maintain the target frequency. We confirmed the accuracy of the film with a laser sensor and tested the ability of the feedback system to match a target frequency by changing the physical load placed on the motor. A user study showed that subjects perceived a difference in vibration intensity under loaded conditions with and without our compensation system, indicating the usefulness of such a feedback system on influencing perception. The results can help designers create better interfaces when vibrotactile cues are employed.

Gait collector: An automatic gait data collection system in conjunction with an experience-based long-run exhibition

Biometric data collection is an important first step toward biometrics research practice, although it is a considerably laborious task, particularly for behavioral biometrics such as gait. We therefore propose an automatic gait data collection system in conjunction with an experience-based exhibition. In the exhibition, participants enjoy an attractive online demonstration of state-of-the-art video-based gait analysis comprising intuitive gait feature measurement and gait-based age estimation while we simultaneously collect their gait data along with informed consent. At the time of this publication, we are holding the exhibition in association with a science museum and have successfully collected the gait data of 47,615 subjects over 246 days, which has already exceeded the size of the largest existing gait database in the world.

Fingernail-mounted display of attraction force and texture

The paper studies two methods of haptic. One is an attraction force display that can induce attraction force by a cyclic movement of a weight with asymmetric acceleration. Another is a texture display that induces a sensation of texture by giving off vibration while a subject traces a finger over a flat surface. In this paper, we propose a novel design that can induce both attraction force and texture feeling. The prototype consists of four vibration motors, which are controlled to generate asymmetric acceleration and vibration. The device is evaluated by experiments.

Controlling the Perceived Vibrational Frequency and Amplitude of a Voice-Coil-Type Tactor

When designing a vibrotactile information display, it is important to present correct, stable stimulation. However, the mechanical stability of the vibration is affected by many conditions such as how the vibrators are attached to the person, where they are attached, and other factors. In order to maintain the target frequency and amplitude of the vibration independent of the affective factors, we propose a feedback method for vibrotactile displays.

Detecting CNV-like variation when remembering and generating continuous motion

Our aim of this study is to investigate the possibility of estimating interruptibility from Electroencephalograms (EEG). We focus on contingent negative variation which is elicited in response to concentration. Our results support that our method could correctly detects the users internal states such as just watching or actively remembering even the external situations were completely same and also CNV is elicited when controlling continuous motion.

Pseudo-attraction force display using vibrating motors — Design of asymmetric oscillation for generating an illusion of being pulled

We developed a new pseudo-attraction force display using four vibrating motors. The advantage of this device is that it uses phase difference control to alter the time width of pulses to generate asymmetric oscillation. It does not require altering the frequency of the vibrating motors. In this study, we investigated the influence of the pulse width generated in the device using vibrating motors on the perceptive intensity of pseudo-attraction force. From the result, the oscillation having shorter pulse widths within the range of 10–20 ms induced the “being-pulled” sensation more strongly.