The causes of passengers' seasickness and fatigue have not been clarified. Our previous studies found that variabilities in heart rates were generated by passengers' postural control. However, passengers' standing postural motions caused by their postural control have not been analyzed enough. The purpose of this study is to elucidate the characteristics of passengers' standing postural motion against ship motion.Our measurement system consists of 3 orientation sensors. They were placed on the head and the waist of a subject, as well as on the floor of a small craft. They measured linear and angular acceleration. The frames of these sensors were transformed to a fixed coordinate system to compare the motion of the floor with subjects’ postural motion. Linear and angular acceleration were analyzed by the root mean square (RMS). RMS values of the subjects and a vertical standing rod were compared.The values of subjects' angular accelerations were larger than the floor values (p<0.05) and were changed along with the floor vertical acceleration. However, the values of the rod’s angular accelerations were smaller than its linear accelerations. These results suggest that passengers control their posture using rotational motion of the head and the waist against the floor vertical acceleration.

View full abstract

Transcranial magnetic stimulation (TMS) is one of the useful tools as an electrophysiological technique to elucidate neural mechanism underlying human behavior. In order to acquire validated motor evoked potentials (MEPs) during dynamic motion such as walking, it is necessary to precisely place TMS coil to the target on subjects' scalp. In this study, we developed a coil navigation system for accomplishing precise coil placement even though the subject's head is moved. Since the system enables us to record the coil position data, it is possible to ascertain whether the coil is suitably placed on the target or not. In order to evaluate the feasibility of the use of our system, sham TMS was applied during treadmill walking with or without using the developed system. The results demonstrated that the variances of coil location and distance from the target site (consistent error) could be minimized with using the system. Our developed coil navigation system enabled us to realize high precision and accuracy in TMS coil placement even during walking.

View full abstract

Wandering of elderly people with dementia is a severe behavioral problem and is a heavy burden on caregivers in residential and nursing homes. We developed a support system that employs image-sequence processing technology based on fluorescent dye. This real-time system captures an image before and after the black light irradiation and identify whether fluorescent dye is painted clothes. The subject wore 12 kinds of T-shirt, 11 kinds of T-shirt which fluorescent dye was painted and a T-shirt which does not, and walked toward the door. When the subjects who wore the clothes approached to the door, the system detected correctly 98.1 % of the dye from capturing images and the alarm turned on. Thus, it is expected that developed system in this study helps the early detection of the wandering of elderly people with dementia to the residential outside.

View full abstract

Higher brain dysfunction (HBD) is an aftereffect of traumatic brain injuries, cerebrovascular disturbances, encephalitis, and so forth. HBD is an umbrella term that encompasses cognitive dysfunction, e.g., memory defects, inability to pay attention, and topographical disorientation. Topographical disorientation prevents persons with HBD from walking alone outdoors. In this study, navigation software was developed to enable persons with HBD to walk independently. It helps users navigate by showing the route of each sub-goal in turn; these are set by tapping on the map in advance. Messages are output when the user reaches the sub-goal or goes off-route in order to attract attention. In an experiment, three non-disabled persons set sub-goals, and the errors in the coordinates were measured. The results showed that the error distance increased when more sub-goals were set for a route. Six non-disabled persons were asked to evaluate and compare the navigation software with a paper map. The navigation software scored higher. Four subjects with HBD evaluated the software by walking inside and outside the National Rehabilitation Center. One subject could not use the navigation software because he had difficulty with the tapping task. Another subject could not walk outside the center with the paper map but could reach the goal with the developed software. The other two subjects were able to reach the goal with both the paper map and the developed software. Several subjects and their parents suggested that voice or vibration feedback is necessary because gazing at the smartphone during walking is dangerous.

View full abstract