Accelerometer based measurement of body movement for communication, play, and creative expression

This paper presents a newly designed wireless accelerometer-based movement measurement device. The device is capable of measuring activity ranging from gross body movements to more subtle vibrations emanating from the body, including laryngeal vibration and the mechanomyogram (mechanical vibrations from working muscles). The main body of the device, which is less than 20cm ³ in volume and weighs less than 50g, contains a microcontroller, wireless transceiver, battery, and one accelerometer. A supplementary accelerometer module is connected to the main device by thin wires. This module is very light weight and can therefore be directly attached to the skin to measure laryngeal vibration, mechanomyogram, or cardiac muscle movement. The prototype device has been initially applied to facilitating play and creative expression by children with physical disabilities. For this purpose, the main module was adapted to be worn behind the ear while the supplementary accelerometer module is attached to the skin over the larynx. In this paper, the device has been adapted to allow guidance of a radio controlled toy car. Direction is controlled by tilting the head, as measured by the accelerometer in the main device. The supplementary accelerometer is used to measure vocal pitch which controls the car's speed. The device has also been adapted to control a music synthesizer, with frequency of phonation controlling musical pitch while head position, which is measured by the main device's accelerometer, controls another parameter such as timbre. Preliminary user trials with five subjects were carried out in these two applications and the results are presented. The system is also readily amenable to adaptation for other applications such as wheelchair navigation, mouse pointer control, or computer game input.