Takafumi Asao

Design of Eye-Typing Interface Using Saccadic Latency of Eye Movement

The objective of this study was to construct and empirically evaluate an improved, online eye-typing interface with respect to its practical usability. The system used the concept of saccadic latency, a silent period of 200 to 250 msec precedes the initiation of a saccade, for identifying the users intentional text entry. Ten individuals participated in the experiment that was conducted on 2 consecutive days, with three blocks of trials conducted on each day. A block included five trials, each of which involved completing the text entry of a short sentence using this eye-typing interface. The proposed interface was evaluated by the users performance based on indices including typing speed and an error index. For defining the error index, the overproduction rates (ORs) were used. The results showed an average OR of 0.032 and average typing speed of 27.1 characters typed per minute. The result revealed that the typing speed changed as an effect of participant, day, and block. The characteristics of the proposed interface with the related characteristics of an eye-typing interface were summarized to discuss a further study for the eye-typing interface.

Changes in posture of the upper extremity through the use of various sizes of tablets and characters

The aim of this study was to analyze the posture of the upper extremities during the use of mobile communication devices. Using various sizes of mobile devices and display characters, we examined subjective muscular loads, viewing distances, and joint angles in the head, neck, shoulder, elbow, and lower back. No postural differences were found between the use of 7-in and 10-in devices, whereas the head and neck were significantly flexed and the elbow angles were decreased during the use of the 13-in device. Character size significantly affected the viewing distance; however, no differences in body angles were found. Participants continually increased their muscular loads during the task by flexing the head and neck, despite their high subjective discomfort levels in the neck and upper arm.

Evaluation for emergency escape during stair climbing in a simulated flood evacuation

The objective of this study was to measure muscle activity during stair-climbing in order to estimate the water depth at which people can evacuate safely from urban underground. A life-size model of a staircase with a water pump that generated water flow from the top of stairs was constructed. In the study, electromyogram data were measured for six muscles on the right lower extremity, namely, the rectus femoris, vastus lateralis, long head of the biceps femoris, medial gastrocnemius, tibialis anterior, and gluteus maximus. From the results, the GA exhibited the highest muscle activity in the latter part of the stance phase, suggesting that the subjects tended to avoid stumbling against the stream of the water during ankle planter flexion. The results obtained from this study would be used for the construction of a guideline for evacuation from urban underground in flood disaster.

Information processing for constructing tactile perception of motion: a MEG study

We clarified whether temporal changes in information processing exist by comparing real and apparent motion conditions when tactile moving perception was given. We used magnetoencephalography (MEG), which has a high temporal resolution, to capture the dynamic changes in brain information processing. As a result, it was revealed that temporal transition through several cortexes was shown in which initial information processing occurred in the somatosensory cortex, followed by MT/V5, and then the activity was transmitted to motor-related areas when tactile moving stimuli were given.

Hands-free data manipulation for visual inspection system by using temporal characteristics of saccades

In some industrial inspection processes, multi-process, handling workers are required for entering the results of visual inspection tests without using their hands, for efficiency or hygiene reasons. We developed a hands-free visual inspection system by using temporal characteristics of saccadic eye movements. The proposed system is free from the Midas touch problem, i.e., the difficulty in developing an eye-typing interface owing to the difficulty in differentiating between intentional blinks and gazes and natural ones. For verifying the system, an experiment was conducted where five subjects performed a visual inspection task. The average defect detection rates were 85.8%, and no Midas-touch-related errors were observed. Results of error analysis showed that redesigning of the system interface would lead to an enhancement of the system performance.

A Study on Fundamental Information Transmission Characteristics of an Air-Jet Driven Tactile Display

There are many people with impaired vision as well as hearing. Tactile displays can be useful to such people for communicating by means of characters and shapes. Many devices for tactile displays such as oscillators and electrocutaneous stimulators have been developed. However oscillators have two drawbacks: physical stress tends to build up in actuators because of long term exposure to oscillations, and they may transmit erroneous information because of unstable contacts between magnetic pins and the skin. Moreover, electrocutaneous stimulators cause discomfort to the user. In this study, we have developed a tactile information presentation technique that uses air jet stimulations and tactile phantom sensations induced by a complex combination of tactile perceptions. The tactile display can transmit information to the skin without physical contact and is free from the restriction of pitch size. In this paper, we have examined its fundamental information transmission characteristics.

Evaluation of Discomfort Degree Estimation System with Pupil Variation in Partial 3D Images

The purpose of this paper was to examine whether the changes in pupil diameter can refrect on the degree of discomfort by various levels of partial 3D images as well as other validated characteristics. Moreover, we discuss the effectiveness of the systems while guiding visual attention by partial 3D images. Images chosen from IAPS (International Affective Picture System) were used to make 3D images. Power spectrum ratio of the pupil variation, called S/C value, generated by stimuli images to those by control images was calculated. The relationship between VAS scores for the impression regarding projected images and the S/C values was set to the major concern for this study. As a result, the average S/C values in 2D neutral images ranged 0.634 to 1.318, whereas the average S/C values in partial 3D neutral images ranged 0.412 to 1.552. VAS scores in 2D neutral images ranged 3.6 to 8.5 and that in partial 3D neutral images ranged 1.2 to 7.4. Moreover, correlation coefficients between VAS scores and S/C values in 2D neutral images was 0.116 and those in partial 3D neutral images was −0.114. In partial 3D images, this negative correlation coefficient was found in consistent with the previous study, whereas the correlation coefficients for both images were relatively low. It was suggested that S/C value was likely to use as a candidate for discomfort measure with a modification of collection technique for VAS scores during the experiment.

Comparison of Electromyogram During Ball Catching Task in Haptic VR and Real Environment

The objective of this study was to construct systems for haptic virtual reality (VR) environment and to conduct an experiment to compare muscular activity during ball catching tasks in real and VR environments, where the level of the presence was evaluated. A ball catching task was demonstrated in two environments, where head-mounted display and SPIDAR-HS, the haptic presentation device using tensile force of the wire, were applied for constructing VR environment. As an index of dynamic muscular activity, forearm EMG signals were measured in the time course of a ball catching task. Average peak RMS value for forearm EMG in VR environment was 45.2% smaller than that in real environment. This difference was apparent because the amount of force generated by SPIDAR-HS was relatively lower than that made by the gravity force of the ball. On the other hand, the trends in dynamic muscular activities were similar for both environment, indicating that two tasks were fairly unique regardless the type of environments. It was concluded that the presence of VR was observable by the dynamic muscular changes during VR tasks with further adjustment of force levels required for the task in VR environment.

Effectiveness of Stability Evaluation by Acceleration and Angular Velocity While Operating Smartphones

The objective of this study was to investigate the effectiveness of evaluating the stability by accelerometer and gyroscope built in smartphone while users were operating smartphones. A total of three smartphones with different sizes were used for the experiment. The swaying caused by the unstable operation of the smartphone was measured as acceleration and angular velocity and components related to stability were extracted. Since the weight of smartphones differed from one type to another, when the difference between the smartphones was evaluated, the acceleration was converted into force. Participants were asked to evaluate the stability during operation and the risk of dropping. The result showed that the force and angular velocity increased as the smartphone size increased. As the hands of the participants became smaller, the acceleration and angular velocity were increased. It was found that the stability during operation was evaluated as uncomfortable as the force and angular velocity became larger. On the other hand, there was no relationship between the risk of dropping and the force and angular velocity. From these results, acceleration and angular velocity appeared to be effective for evaluation of stability while operating smartphones.

Empirical Study of Physiological Characteristics Accompanied by Tactile Thermal Perception

This paper presents empirical results regarding emotional changes represented using different thermal gradients by measuring skin conductance responses (SCRs), when providing thermal information with various gradients. Participants attached a probe in their right forearm for thermal stimuli, and SCR measurements were conducted when participants perceived the time to detect a temperature change. The SCR amplitude showed a significant tendency to vary between +0.5 and �0.5 (°C/s) and between +0.5 and �0.3 (°C/s) of thermal gradients. The results of this study showed that differences in clear thermal gradients, such as the comparison between warm and cold stimuli, affected emotion, and differences in detailed thermal gradients, such as the comparison between 0.3 and 0.5 (°C/s) of thermal gradients, did not affect the changes in emotion.