Tongue in cheek: a novel concept in assistive human-machine interface

In this paper we describe a novel human machine interface system aimed primarily at those who have experienced loss of extremity motor function. The system enables the control of a wide range of assistive technologies such as wheelchairs, prosthetics, computers and general electrical goods at the ‘flick of a tongue’. This system could benefit a huge sector of people including those who have suffered a spinal cord injury, stroke or quadriplegia. The technology focuses on a unique hands-free interface whereby users can issue commands simply by performing subtle tongue movements; these tongue motions are continually monitored by a small microphone positioned comfortably within the ear canal. Due to the physiological connections between these regions and the distinctive nature of the signals, these commands can be detected and distinguished allowing a control signal to be issued. This inexpensive device offers significant advantages over existing technologies by providing unobtrusive, hygienic control through natural tongue motion. New software has been implemented, achieving over 97% correct classification across four different tongue movements for seven test subjects. Feasibility of the system as an interface for a variety of devices is demonstrated through simulation studies including controlling a prosthetic manipulator and power wheelchair.