A Care System for the Aged

四种氧化锡气体传感器安装在一个孤独的老人家和传感器的输出进行监测，以了解老年人的活动。这些传感器设计用于分别检测可燃气体（CGS）、氨（AMS）、一氧化碳（COS）和二氧化氮（NXS）。如监测结果所示，传感器的输出与日常生活模式有关。NDVA指数尤其具有周期性。NDVA是通过AMS的输出除以CGS的输出而获得的值，即NDVA=V（AMS）/V（CGS）。周期性特征反映了老年人的日常生活模式，系统可以判断老年人是否在正常生活。室内活动（IA）是从每日传感器水平的平均值导出的每个滑动值的平方和。在实验室中，IA的平均值约为12。

Four kinds of tin-oxide gas sensors are installed in a home of a solitary elderly person and the sensor outputs are monitored to know the activity of the aged. These sensors are designed to detect a combustible gas (CGS), ammonia (AMS), carbon monoxide (COS) and nitrogen dioxide (NXS), respectively. As the monitoring results indicate, outputs of the sensors are related with daily living patterns. NDVA indeces especially have periodicity. NDVA is a value which is obtained by an putput of AMS divided by an output of CGS,namely NDVA=V (AMS) /V (CGS). The periodical characteristics indicate the daily living patterns of the aged and the system can judge whether the person has been spending a normal life or not. The indoor activity (IA) is derived as a sum total of square of each slipped value from a mean value of a daily sensor-level. The average of IA is about 12 in the experimental house.