Abstract
In many developed countries, it is one of the urgent issues to find a way to maintain the health of the elderly people. Specifically, it is desired to monitor always individual elderly living alone or with others, and to notice even a slight lowering of his/her physical ability. A change of the person’s gait is useful for this aim. It is said to be a sign of aging, weakening, and diseases. Especially, it needs to be careful of the risk of dementia when the gait speed falls below a certain standard. Indeed, many studies focus on the gait speed to find some diseases or to detect cognitive decline of the elderly at an early stage. Most of them use digital cameras or accelerometer, but cameras are not always preferable in viewpoint of privacy protection and elderly people may feel unpleasant in forcible attachment of sensors to their bodies. Cameras are also sensitive to the light condition. In this study, therefore, we propose a system in which two analog-output infrared sensors are installed on the ceiling and used for collecting gait data of people passing under the sensors. The record is finally summarized as a monthly report to serve a diagnosis on the degradation of walking ability. The two sensors are used not only to measure the gait speed but also to record the gait waveform for detailed analysis. It is also necessary to know who each pedestrian is. For this goal, we use a finger vein authentication device that locks/unlocks the door at a room.
To confirm the validity of our system, we conducted an experiment. The estimated gait speeds had the absolute mean error of 0.025 m/s (standard deviation 0.029). This accuracy seems to be sufficient to study a daily variation. In addition, we succeeded in recording the gait speeds of 12 people for a month. The record not only shows the trend of each individual person over days, but also reveals the variance of gait speed of the same person a day. Indeed, we noticed that some people change the speed largely during a day.
https://ror.org/02e16g702 
