Summer 2008

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.

photo by Gary Meek Assistant professor Maysam Ghovanloo (left) points to the Tongue Drive system being used by graduate student Xueliang Huo.

“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,” says 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 in June 2008 at the Rehabilitation Engineering and Assistive Technology Society of North America (RESNA) Annual Conference in Washington, D.C. An article about this system is available online in the journal IEEE Transactions on Neural Systems and Rehabilitation Engineering. This research was funded by the National Science Foundation and the Christopher 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,” says 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,” Ghovanloo explains. “The ability to train our system with as many commands as an individual can comfortably remember is a significant advantage over the common sip-and-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. 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.

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. The researchers have also tested the ability of 12 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, says 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.

“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 health care and assisted living costs,” Ghovanloo adds. “This system may also make it easier for them to work and communicate with others, such as friends and family.”