Location system for dementia wandering

A telemetry technique has been developed to locate a patient of dementia wandering. The patient carries a responder which consists of a mobile phone terminal and a GPS receiver. A family member or a nurse calls up the responder by a telephone network and finds the location of the patient on the map displayed on a CRT. An experimental system was developed and its performance was tested in various adverse conditions. The GPS receiver was vertically attached against the chest wall of a subject and covered with thick clothes. The subject walked around various areas such as the urban area with many tall buildings as well as the suburban areas. Even in unfavorable conditions, the subject was located within 100 m error in most cases. Through these experiments, the fundamental feasibility of this technique was verified, In the field experiments, some problems were found to be solved for the practical use of this technique. They were: the effect of weather conditions, the problem of network interruptions of a mobile phone, the problem of the locations where the GPS radio wave cannot reach, and the problem of the location error of GPS. The solutions for these problems were worked out, and the practicality of the proposed technique was improved considerably.