A rocking motion sensor for the blind

Rocking motion is an unconscious and often unwanted phenomenon exhibited by the blind. It is usually manifested in oscillatory back and forth, side to side, or rotatory movements of the upper torso or head at about 1 Hz rate. Subjects desiring to function unobtrusively in the world of the sighted need to be alerted when rocking so they can control it. The rocking motion sensor incorporates biofeedback and records rock occurrences. A miniature body mounted accelerometer senses body accelerations exceeding 0.1g. These motions during a given period, compared with a presettable "rock threshold", discriminate rocking from normal activities. Sound biofeedback alerts the subject that he has exceeded threshold. Another counting and timing subsystem determines "end of rock" and resets the system. A recorder is provided that records signals only during rocking. Timing information is provided on a separate channel to permit later time line analysis. The rocking motion sensor system utilizes primarily solid state CMOS circuits with a combination of synchronous-asynchronous timing. The recorder is a modified commercial unit. The two units are separate, portable, and belt mounted. Tests have been made and results will be presented.