The mechanomyogram as a channel of communication and control for the disabled

This paper describes an original system to provide a communication and control tool for people who are disabled. The mechanomyogram (MMG) is used as a control signal to operate an alphabet board. The MMG is the mechanical signal observable at the surface of a muscle due to vibration of the motor units underneath. Contraction of the muscle increases the amplitude of the vibrations. The system described detects the MMG from either the biceps brachii or the sternocleidomastoid muscle using a dual-axis accelerometer. The signal is read into the computer and processed. A decision is made as to whether the muscle is contracted or relaxed based on the amplitude of the processed signal. If the computer decides that the muscle is contracted, a software switching action is performed. This switching action is used to control a software alphabet board which the disabled person can use to spell out messages.