A novel tongue controller designed for the disabled to operate computers, wheelchairs, etc., is being developed at Georgia Tech. The device uses two magnetic field sensors to detect the movement of a small magnet attached to the tongue, which in turn send data to a control computer for interpretation.
Movement of the magnetic tracer attached to the tongue is detected by an array of magnetic field sensors mounted on a headset outside the mouth or on an orthodontic brace inside the mouth. The sensor output signals are wirelessly transmitted to a portable computer, which can be carried on the user’s clothing or wheelchair.
The sensor output signals are processed to determine the relative motion of the magnet with respect to the array of sensors in real-time. This information is then used to control the movements of a cursor on the computer screen or to substitute for the joystick function in a powered wheelchair.
The system can potentially capture a large number of tongue movements, each of which can represent a different user command. A unique set of specific tongue movements can be tailored for each individual based on the user’s abilities, oral anatomy, personal preferences and lifestyle.
“An individual could potentially train our system to recognize touching each tooth as a different command,” explained Ghovanloo [Maysam Ghovanloo, assistant professor at Georgia Tech School of Electrical and Computer Engineering –ed.]. “The ability to train our system with as many commands as an individual can comfortably remember is a significant advantage over the common sip-n-puff device that acts as a simple switch controlled by sucking or blowing through a straw.”
Ghovanloo’s group recently completed trials in which six able-bodied individuals tested the Tongue Drive system. Each participant defined six tongue commands that would substitute for computer mouse tasks – left, right, up and down pointer movements and single- and double-click. For each trial, the individual began by training the system. During the five-minute training session, the individual repeated each of the six designated tongue movements 10 times.
During the testing session, the user moved his or her tongue to one of the predefined command positions and the mouse pointer started moving in the selected direction. To move the cursor faster, users could hold their tongue in the position of the issued command to gradually accelerate the pointer until it reached a maximum velocity.
Results of the computer access test by novice users with the current Tongue Drive prototype showed a response time of less than one second with almost 100 percent accuracy for the six individual commands. This is equivalent to an information transfer rate of approximately 150 bits per minute, which is much faster than the bandwidth of most brain-computer interfaces, according to Ghovanloo.
Press release: Tongue-controlled System Assists Individuals with Disabilities …
Video of Dr Maysam Ghovanloo describing the workings of the device and a demonstration by a student controlling a wheelchair with his tongue.
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