”THE TONGUE DRIVE SYSTEM”

DEFINITION:
The "Tongue Drive" system is a tongue-operated assistive technology developed for people with severe disability to control their environment. The tongue is considered an excellent appendage in severely disabled people for operating an assistive device.
WHY THE TONGUE?
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.
WHAT IS THIS ALL ABOUT?

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.

HOW DOES IT WORK?

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.
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.
The Tongue Drive system is also non-invasive and does not require brain surgery like some of the brain-computer interface technologies.

There are 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 .
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.
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.

ADVANTAGES OF TONGUE DRIVE SYSTEM:

 The signals from the magnetic sensors are linear functions the magnetic field, which is a continuous position dependent property. Thus a few sensors are able to capture a wide variety of tongue movements.
 This would provide a tremendous advantage over switch based devices in that the user has the options of proportional, fuzzy, or adaptive control over the environment.
 These would offer smoother, faster, and more natural controls as the user is saved the trouble of multiple on/off switch operations. Alternative assistive technologies that emulate a computer mouse use an additional input device such as a switch for the mouse button clicks besides the primary method for moving the pointer.
 In Tongue Drive system on the other hand, the additional switches are unnecessary since a specific tongue movement can be assigned to the button press.
 The permanent magnet which generates the magnetic field is a small, passive, and inherently wireless component leading to user convenience and additional power saving mouthpiece electronics can be integrated circuit (AISC). The AISC along with the transmitter antenna can be incorporated into a miniaturized package that may be fitted under the tongue as part of the dental retainer.

DISADVANTAGES OF TONGUE DRIVE SYSTEM:

 Implementation is slightly harder.
 Slightly costlier.

CONCLUSION:

 A tongue operated magnetic sensor based wireless assistive technology has been developed for people with severe disabilities to lead a self-supportive independent life enabling them to control their environment using their tongue. This technology works by tracking movements of permanent magnet, secured on the tongue, utilizing an array of linear Hall-effect sensors. The sensor outputs are a function of the position-dependent magnetic field generated by the permanent magnet. This allows a small array of sensors to capture a large number of tongue movements. Thus, providing quicker, smoother, and more convenient proportional control compared to many existing assistive technologies. Other advantages of the Tongue Drive system are being unobtrusive, low cost, minimally invasive, flexible, and easy to operate. A more advanced version with custom designed low-power electronics that entirely fit within the mouthpiece is currently under development.

PREPARED BY:
HAZEL PACLAR
FLOWER MAE NUGAS
ESTHER JOY DE ASIS