As we know, regular walking has been
recognized as an effective method to reduce the risk
of chronic illness. However, for some elderly people,
due to the gradual degradation of their cognitive
function, a regular walk might become a
missing-person occurrence. This study therefore
establishes a customized safety area as the second
feature to assist this group of people. Normally, the
safety region, such as a nearby park, grocery stores,
library, bank, or some shops, can be deemed as
familiar locations for an elderly individual and can be
set as a safety zone. Inside this area, the system will
not issue any alert alarm. The GPS coordinates, i.e.,
the longitude and latitude, of such neighborhood
features as are listed above can be set up by inputting
those data directly if the user has this information or
by using the PTFaD to read the GPS coordinates.
Also, to make this system operate smoothly, when the
system is started up, the smartphone is able to automatically turn on its Bluetooth and WiFi
functions to increase the accuracy of positioning.
In the present study, the first layer of the safety
zone is set to within a radius of 300 meters. That
distance is considered a safe area for the elderly (see
Figure 4). The second layer of the safety zone is set
to within a radius of 500 meters. If the elderly
individual stays between 300 meters and 500 meters,
the system will trigger the alert function. The alert
system first broadcasts pre-recorded voice files by the
elderly individual’s family to request the elderly
individual not to go too far and to ask that elderly
individual to go home soon. The voice messages
should be something like, “You are too far away from
home; please come back as soon as possible.” For
those people in early stages of dementia, that
message plausibly makes sense. For people in later
stages of dementia, although they may have lost the
ability to go home by themselves, those pre-recorded
voice messages provide opportunities for bystanders
or police to better understand what that elderly
individual needs.