DEVELOPMENT OF LOCATION SYSTEM
FOR WANDERING PERSON

Koichi Shimizu, Kuniaki Kawamura and Katsuyuki Yamamoto
Department of Bioengineering, Graduate School of Engineering,
Hokkaido University, Sapporo, 060, Japan

INTRODUCTION With the increase of aged population and so called nuclear families, the problem of dementia wandering has been increasingly serious in our society. The restriction of free activity of the patient tends to make the symptom severer than before. A practical system has been required which can locate the patient on the demand of the nurse or a family member. We have developed a telemetry technique to locate the patient before he/she meets a serious accident.

METHOD The technique developed uses a mobile phone and a global positioning system (GPS). Fig.1 illustrates the principle of the location system developed. This system consists of the responder to be carried by a patient and a telephone terminal with a personal computer in a home. The responder consists of a GPS receiver and a mobile telephone terminal. First, a family member of the patient called the responder by dialing the number of the mobile phone. Then, the location signal of the GPS is sent back through the mobile telephone network. In a home, the position of the patient is indicated on a geographical map displayed by a microcomputer.

EXPERIMENT AND RESULTS To examine the feasibility of this technique, an experimental system was developed. Using this system the location of a walking subject was attempted. The effects of weather conditions and tall buildings were investigated. As the conditions became unfavorable, the blind-time increased. However, the location was possible at least once in every several minutes.

The location error was generally within 100m. In these experiments, the fundamental feasibility of this technique was verified, and some practical problems were found.