Katsuya Matsunaga

Detecting drowsiness while driving by measuring eye movement - a pilot study

A function to warn a drowsy driver is a prospective device to be included in intelligent transportation systems. We compared the eye closure rate (PERCLOS) with the vertical eye movement frequency between wakeful and drowsy states of drivers who were driving a car in a driving simulator. Three subjects participated in the experiment. In the drowsy state condition, both measures showed high values in frequency, which was significant enough to distinguish between the two states with a threshold. The threshold level, which can distinguish the two states, is defined as the rate at the cross point of the curves of two possibility density functions made by the frequency of the rates of the two measures at the two states. The distinction error was evaluated for three analysis durations. As a result of the analysis, it was found that the better measure was different for each subject.

Smooth pursuit eye movements of normal and schizophrenic subjects tracking an unpredictable target

An experimental paradigm employed by several workers in the field of schizophrenic eye movements has involved finding sequences of stimuli that induce saccadic smooth pursuit in the eye movements of normal individuals. It is hoped that the identification of such stimuli will lead to clues concerning the etiology or nature of eye tracking dysfunction in schizophrenia. In this study, the pursuit eye movements of normal and schizophrenic subjects tracking an unpredictable target (composed of summed sine waves) were examined. Eye tracking performance was evaluated both qualitatively and quantitatively using percent root-mean-square (%RMS) error and pursuit gain scores. Schizophrenics are capable of tracking an unpredictable target. This finding has implications for our understanding of schizophrenic information processing during visual tracking.

Tele-presence information and remote-controlled task execution

We developed a remote-controlled system which enabled us to effectively control remote construction machinery such as a backhoe shovel, wheel dump and bulldozer using video images at a safe distance and in a comfortable environment. We used this system for one year at Mt. Fugen, an active volcano in Shimabara City of Nagasaki Prefecture, which is known for the disaster in which a large scale pyroclastic eruption killed many people.

The cause of traffic accidents when drivers use car phones and the functional requirements of car phones for safe driving

This paper reports how driving behaviour is affected by the use of mobile phones. We measured the reaction time (RT) in various conditions to detect what kind of effects mobile phone use has in the face of accidents. It is important to study RT in driving because the stopping distance of the car varies with the drivers RT. For this study, we prepared a system which measures the time from when a lamp mounted on the windshield of the car lights up to when the driver steps on the brake pedal. The RT was measured under three conditions: a) During a conversation using a handset b) During a manual task with a handset c) During a manual task with a handset, with eyes on the road ahead. The results of our experiments showed that the RT was prolonged unexpectedly when the driver took his eyes off the road to make or to take a phone call. The main effect of the car phone appears to be on the distraction of visual attention, rather than on physical or mental demand in operating the phone and engaging in a conversation.

Development of a portable teleoperated robot for the manipulation of a backhoe shovel for the restoration of disaster-stricken sites

Restoration activities after disasters such as landslides or rock avalanches require rapid action, but in fact, in most cases these activities are very inefficient because of the danger of secondary disasters. A system which can operate reconstruction machinery by remote control was therefore developed, and it was installed on general-purpose construction machines (backhoe shovels). Control performance experiments and field experiments on this developed system were carried out, and its effectiveness was confirmed.

FIELD DEPENDENCE AND BODY BALANCE

This study reports four points about the portable Rod and Frame Test performance of 30 Japanese women in terms of body balance. The primary findings using a stabilometer are: (a) field dependence correlated negatively with increased sway path within 1 min. both while a dot pattern as a visual stimulus was stationary and while it was moving. (b) Field dependence correlated positively with the difference in sway path between the two following phases, in one of which the subjects watched the horizontal visual movement to the right and in the other movement to the left. (c) Motion aftereffect had no direct and immediate influence on sway path, but rather a latent and long-term effect. And on a pedograph which measures the distribution of foot pressure and the shape of the sole, (d) field dependence correlated negatively with anterior positions of the center of foot pressure and with the proportion of the front part to the rear of the sole. Over-all, field dependence measured by the Rod and Frame Test seems to be associated with body posture when dot patterns are viewed.

New stereoscopic video camera and monitor system with central high resolution

A new stereoscopic video system (the Q stereoscopic video system), which has high resolution in the central area, has been developed using four video cameras and four video displays. The Q stereoscopic camera system is constructed using two cameras with wide-angle lenses, which are combined as the stereoscopic camera system, and two cameras with narrow-angle lenses, which are combined (using half mirrors) with each of the wide-angle cameras to have the same optical center axis. The Q stereoscopic display system is composed of two large video displays that receive images from the wide-angle stereoscopic cameras, and two smaller displays projecting images from the narrow-angle cameras. With this system, human operators are able to see the stereoscopic images of the smaller displays inserted in the images of the larger displays. Completion times for the pick-up task of a remote controlled robot were shorter when using the Q stereoscopic video system rather than a conventional stereoscopic video system.

Evaluation of stereoscopic video cameras synchronized with the movement of an operator's head on the teleoperation of the actual backhoe shovel

Operator performance while using a remote controlled backhoe shovel is described for three different stereoscopic viewing conditions: direct view, fixed stereoscopic cameras connected to a helmet mounted display (HMD), and rotating stereo camera connected and slaved to the head orientation of a free moving stereo HMD. Results showed that the head- slaved system provided the best performance.

Effect of overlap rate between stereoscopic images on performance in a teleoperation

According to the results of the simulated teleoperation experiment, the larger the ratio of the overlapping area of stereoscopic images, the smaller the completion times and the number of errors. For this paper we did an experiment using the actual stereoscopic video system. We examined the performance of the teleoperation of an insert task in two experiments. In experiment 1, we set three fixed overlap rate conditions for the stereoscopic image pairs. (High overlap rate condition): The convergence point of the two cameras was set at the goal point where a cylindrical object was inserted. When subjects fixated their eyes on the goal point, the overlap rate of the images from the cameras was 95%. (Middle overlap rate condition): The convergence point of the cameras was set at the center of the working area. When subjects fixated their eyes on the goal points, it was 76.7%. (Low overlap rate condition): Convergence point of the camera was set at the point in the situation where the ratio of the overlapped area was 49% when subjects fixated to the goal point. Completion times and the numbers of errors of the insert task were measured. As a result, these were smallest at the high overlap rate condition. In experiment 2, we compared the performance between a fixed and a variable overlap rate conditions in a pick-and-insert task. The experimental results suggested that the number of errors of variable overlap rate condition was less than that of the fixed condition although the completion time of the former condition was not shorter than that of the latter condition.

Estimation of an unexpected-overlooking error by means of the single eye fixation related potential analysis with wavelet transform filter

An unexpected-overlooking error that caused failure to notice near the peripheral vision is one of the accident factors in driving behavior. We estimated how the unexpected-overlooking error affected the amplitude of the lambda wave in the eye fixation related potential (EFRP). Four subjects participated in the experiment. Each subject was required press the right or left switch according to the given task, which was that he/she pressed the right switch when the blue dot appeared in the right detected area or he/she pressed the left switch when the red dot appeared in the right. The single trial data from Pz, which referred to both earlobes, were analyzed by means of a wavelet transform (WT) filter. The difference of the lambda amplitude between the corrected data was applied for analysis of variance. Three subjects showed a significant effect (P<0.01 or P<0.05), and the remaining one subject did not show a significant consequence of only two errors. The unexpected-overlooking errors had a low amplitude compared to the mean of amplitude throughout the task. It was concluded that the amplitude of the lambda wave might reflect the attention level of a subject.