The position sensors or inclinometer detects the angle
between a sensing axis and a reference vector such as gravity
or the earth's magnetic field. It has between used in various
daily environments related to automobiles, and entertainment.
In medicine sciences position sensors have mainly been used
in occupational medicine research. For example, application
of position sensors in gait analysis is also under investigation.
Potentially, position sensors have applications for improving
the function of persons with hand disabilities [7].
Spinal cord injuries (SCI) and disabilities involving paralysis
increasingly utilize electronic assistance devices to improve
their ability to perform certain essential functions. The
functional areas in which the disabled most commonly utilize
electronic equipments are: communications, environmental
control and powered wheelchairs. A wide range of interfaces
between the user and the device is available. The interface
may be an enlarged keyboard or a complex system that allows
the user to operate or control a function with the aid of a
mouthstick, eye movements, an eye imaged input system and
electroencephalogram (EEG) signals [ 1-91 etc.. In many
disabilities such as quadriplegia, the mouthstick method is not
accurate and comfortable. The eye movement and EEG
methods which provide few available controlled movements
have slow response time for signal processing and require
substantial motor coordination. However, these instruments all
tend to be highly specialized and are generally cost
prohibitive. Thus, alternative systems which utilize
commercially available electronics to assist in the performance
of special tasks such as computer operation and environmental
control are sorely needed.