A Self Organizing Map Based Postural Transition Detection System

Abstract

A high percentage of elderly people has been continually increased in every part of the world. This results from the successes of both the advancements of medical knowledge and the high coverage of medical services which altogether make people healthier and live longer. One of the consequences of advancing years is greater frailty due to declining health and mobility, leading to increased risk of injury and fatality due to accidents, especially in the home. It can be said that falls are the most common type of home accidents among elderly people and are a major threat to their health and independence (Najafi, 2002). Thirty-two percent of a sample of community dwelling persons 75 years and older fell at least once a year. Among them, 24% sustained serious injuries (Tinetti, 1988). In addition, falling can dramatically change elderly people’s self-confidence and motivation, affecting their ability to function independently and result in decreased activity, isolation and further functional decline. In addition, the cost of caring for elderly people after a fall is substantial, although estimates vary. Some suggest that fall-related injuries account for 6% of all medical expenditures in the USA (Stevens, 2006). Considering the growing proportion of old people (over 75) in the populations of industrial countries, falls will be one of the major problems of this important part of the population (Askham, 1990). In 2050, 16.4% of the world population and 27.6% of the European population are projected to be 65 years and above, and in 14 countries, including nine European countries, more than 10% of the total population will be 80 years or older. Most cases of falls sustained by elderly people appear to result from the cumulative effect of multiple specific disabilities. The normal changes of aging, like poor eyesight or poor hearing, can make elderly people more likely to fall. Illnesses and physical conditions can affect their strength and balance. Poor lighting or throw rugs in their home can make them more likely to trip or slip. The side effects of some medicines can upset elderly people’s balance and make them fall. Medicines for depression, sleep problems and high blood pressure often cause falls. Some medicines for diabetes and heart conditions can also make them unsteady on their feet. As a way to observe the activities of elderly people in order to prevent and/or alert when they fall, an EKG (Electrocardiogram) sensor, a pulse sensor and a blood pressure sensor are also employed. It is expected that if some measuring parameters are changed, they might result in a severe fall and unconsciousness of elderly people. To function correctly, these sensors must be firmly attached to the body of wearers by a well-trained medical staff. The sensors may cause uncomfortable for wearers and make them lack of self-confidence to live by their own. In addition, from the technical point of view, these sensors consume a high percentage of battery power if they are operated continuously or at the high sampling frequency. The aim 23