Tongue Drive system lets persons with disabilities operate powered wheelchairs,

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Tongue Drive system lets persons with disabilities operate powered

wheelchairs, computers

http://www.eurekalert.org/pub_releases/2008-06/giot-tds062608.php

A new assistive technology developed by engineers at the Georgia

Institute of Technology could help individuals with severe

disabilities lead more independent lives.

The novel system allows individuals with disabilities to operate a

computer, control a powered wheelchair and interact with their

environments simply by moving their tongues.

" This device could revolutionize the field of assistive technologies

by helping individuals with severe disabilities, such as those with

high-level spinal cord injuries, return to rich, active, independent

and productive lives, " said Maysam Ghovanloo, an assistant professor

in the Georgia Tech School of Electrical and Computer Engineering.

Ghovanloo developed the system with graduate student Xueliang Huo.

The tongue-operated assistive technology, called the Tongue Drive

system, was described on June 29 at the 2008 Rehabilitation

Engineering and Assistive Technology Society of North America (RESNA)

Annual Conference in Washington, D.C. An article about this system is

also scheduled to appear in an upcoming issue of the Journal of

Rehabilitation Research and Development. This research was funded by

the National Science Foundation and the and Dana Reeve

Foundation.

To operate the Tongue Drive system, potential users only need to be

able to move their tongues. Attaching a small magnet, the size of a

grain of rice, to an individual's tongue by implantation, piercing or

tissue adhesive allows tongue motion to direct the movement of a

cursor across a computer screen or a powered wheelchair around a room.

" We chose the tongue to operate the system because unlike hands and

feet, which are controlled by the brain through the spinal cord, the

tongue is directly connected to the brain by a cranial nerve that

generally escapes damage in severe spinal cord injuries or

neuromuscular diseases, " said Ghovanloo, who started working on this

project about three years ago at North Carolina State

University. " Tongue movements are also fast, accurate and do not

require much thinking, concentration or effort. "

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. " 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. "

The Tongue Drive system is also non-invasive and does not require

brain surgery like some of the brain-computer interface technologies.

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.

The researchers have also tested the ability of twelve able-bodied

individuals to operate an electric-powered wheelchair with the Tongue

Drive system. The next step is to test and assess the usability and

acceptability of the system by people with severe disabilities, said

Ghovanloo. He is teaming with the Shepherd Center, an Atlanta-based

catastrophic care hospital, and the Georgia Tech Center for Assistive

Technology and Environmental Access, to conduct those trials.

The research team has also begun to develop software to connect the

Tongue Drive system to a wide variety of readily available

communication tools such as text generators, speech synthesizers and

readers. In addition, the researchers plan to add control commands,

such as switching the system into standby mode to permit the user to

eat, sleep or engage in a conversation while extending battery life.

" We hope this technology will reduce the need of individuals with

severe disabilities to receive continuous assistance from family

members or caregivers, thus significantly reducing healthcare and

assistance costs, " noted Ghovanloo. " This system may also make it

easier for them to work and communicate with others, such as friends

and family. "