New Tongue Drive System Uses Dental Retainer to Operate Wheelchair

New Tongue Drive System Uses Dental Retainer to Operate Wheelchair

Mouth Gear: Tongue Drive System Goes Inside the Mouth to Improve Performance and User Comfort

The Tongue Drive System is getting less conspicuous and more capable. Tongue Drive is a wireless device that enables people with high-level spinal cord injuries to operate a computer and maneuver an electrically powered wheelchair simply by moving their tongues.

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The circuitry for the new intraoral Tongue Drive System developed at Georgia Tech is embedded in this dental retainer worn in the mouth (right). The system interprets commands from seven different tongue movements to operate a computer (left) or maneuver an electrically powered wheelchair. (Click image for high-resolution version. Credit: Maysam Ghovanloo)

The newest prototype of the system allows users to wear an inconspicuous dental retainer embedded with sensors to control the system. The sensors track the location of a tiny magnet attached to the tongues of users. In earlier versions of the Tongue Drive System, the sensors that track the movement of the magnet on the tongue were mounted on a headset worn by the user.

“By moving the sensors inside the mouth, we have created a Tongue Drive System with increased mechanical stability and comfort that is nearly unnoticeable,” said Maysam Ghovanloo, an associate professor in the School of Electrical and Computer Engineering at the Georgia Institute of Technology.

The new intraoral Tongue Drive System was presented and demonstrated on Feb. 20, 2012 at the IEEE International Solid-State Circuits Conference in San Francisco. Development of the system is supported by the National Science Foundation, the Christopher and Dana Reeve Foundation, and the National Institute of Biomedical Imaging and Bioengineering at the National Institutes of Health.

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The dental appliance for the new intraoral Tongue Drive System contains magnetic field sensors mounted on its four corners that detect movement of a tiny magnet attached to the tongue. It also includes a rechargeable lithium-ion battery and an induction coil to charge the battery. (Click image for high-resolution version. Credit: Maysam Ghovanloo)

The new dental appliance contains magnetic field sensors mounted on its four corners that detect movement of a tiny magnet attached to the tongue. It also includes a rechargeable lithium-ion battery and an induction coil to charge the battery. The circuitry fits in the space available on the retainer, which sits against the roof of the mouth and is covered with an insulating, water-resistant material and vacuum-molded inside standard dental acrylic.

“One of the problems we encountered with the earlier headset was that it could shift on a user’s head and the system would need to be recalibrated,” explained Ghovanloo. “Because the dental appliance is worn inside the mouth and molded from dental impressions to fit tightly around an individual’s teeth with clasps, it is protected from these types of disturbances.”

When in use, the output signals from the sensors are wirelessly transmitted to an iPod or iPhone. Software installed on the iPod interprets the user’s tongue commands by determining the relative position of the magnet with respect to the array of sensors in real-time. This information is used to control the movements of a cursor on the computer screen or to substitute for the joystick function in a powered wheelchair.

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Georgia Tech researchers designed this universal interface for the intraoral Tongue Drive System that attaches directly to a standard electric wheelchair. The interface boasts multiple functions: it not only holds the iPod, but also wirelessly receives the sensor data and delivers it to the iPod, connects the iPod to the wheelchair, charges the iPod, and includes a container where the dental retainer can be placed at night for charging. (Click image for high-resolution version. Credit: Maysam Ghovanloo)

Ghovanloo and his team have also created a universal interface for the intraoral Tongue Drive System that attaches directly to a standard electric wheelchair. The interface boasts multiple functions: it not only holds the iPod, but also wirelessly receives the sensor data and delivers it to the iPod, connects the iPod to the wheelchair, charges the iPod, and includes a container where the dental retainer can be placed at night for charging.

In preliminary tests, the intraoral device exhibited an increased signal-to-noise ratio, even when a smaller magnet was placed on the tongue. That improved sensitivity could allow additional commands to be programmed into the system. The existing Tongue Drive System that uses a headset interprets commands from seven different tongue movements.

The ability to train the system with additional commands – as many commands as an individual can comfortably remember – and having all of the commands available to the user at the same time are significant advantages over the common sip-n-puff device that acts as a simple switch controlled by sucking or blowing through a straw.

The researchers plan to begin testing the usability of the intraoral Tongue Drive System by able-bodied individuals soon and then move onto clinical trials to test its usability by people with high-level spinal cord injuries.

In recent months, Ghovanloo and his team have recruited 11 individuals with high-level spinal cord injuries to test the headset version of the system at the Atlanta-based Shepherd Center and the Rehabilitation Institute of Chicago. Trial participants received a clinical tongue piercing and tongue stud that contained a tiny magnet embedded in the upper ball. They repeated two test sessions per week during a six-week period that assessed their ability to use the Tongue Drive System to operate a computer and navigate an electric wheelchair through an obstacle course.

“During the trials, users have been able to learn to use the system, move the computer cursor quicker and with more accuracy, and maneuver through the obstacle course faster and with fewer collisions,” said Ghovanloo. “We expect even better results in the future when trial participants begin to use the intraoral Tongue Drive System on a daily basis.”

Georgia Tech graduate students Abner Ayala-Acevedo, Xueliang Huo, Jeonghee Kim, Hangue Park and Xueli Xiao, and former postdoctoral fellow Benoit Gosselin also contributed to this work.

This project was supported in part by the National Science Foundation (NSF) (Award Nos. CBET-0828882, IIS-0953107 and IIS-0803184) and the National Institute of Biomedical Imaging and Bioengineering at the National Institutes of Health (NIH) (Award No. RC1 EB010915-01). The content is solely the responsibility of the principal investigators and does not necessarily represent the official views of the NSF or NIH.

A year ago we wrote about a new tongue controller designed to give quadriplegics the ability to operate external devices like wheelchairs and computers. Now results from a clinical trial testing the capabilities of the interface for the severely handicapped have been presented at the annual meeting of the Rehabilitation Engineering and Assistive Technology Society of North America (RESNA), and they show that the technology is intuitive and precise enough for patients to quickly become acquainted with it in a short period of time.

3mnag42 Tongue Controller Looks Promising For Paralyzed

At the beginning of each trial, Ghovanloo and graduate students Xueliang Huo and Chih-wen Cheng attached a small magnet — the size of a grain of rice — to the participant’s tongue with tissue adhesive. Movement of this magnetic tracer was detected by an array of magnetic field sensors mounted on wireless headphones worn by the subject. The sensor output signals were wirelessly transmitted to a portable computer, which was carried on the wheelchair.

The signals were processed to determine the relative motion of the magnet with respect to the array of sensors in real-time. This information was then used to control the movements of the cursor on a computer screen or to substitute for the joystick function in a powered wheelchair.

Ghovanloo 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.

Before using the Tongue Drive system, the subjects trained the computer to understand how they would like to move their tongues to indicate different commands. A unique set of specific tongue movements was tailored for each individual based on the user’s abilities, oral anatomy and personal preferences. For the first computer test, the user issued commands to move the computer mouse left and right. Using these commands, each subject played a computer game that required moving a paddle horizontally to prevent a ball from hitting the bottom of the screen.

After adding two more commands to their repertoire — up and down — the subjects were asked to move the mouse cursor through an on-screen maze as quickly and accurately as possible.

Then the researchers added two more commands — single and double mouse clicks — to provide the subject with complete mouse functionality. When a randomly selected symbol representing one of the six commands appeared on the computer screen, the subject was instructed to issue that command within a specified time period. Each subject completed 40 trials for each time period.

After the computer sessions, the subjects were ready for the wheelchair driving exercise. Using forward, backward, right, left and stop/neutral tongue commands, the subjects maneuvered a powered wheelchair through an obstacle course.

The obstacle course contained 10 turns and was longer than a professional basketball court. Throughout the course, the users had to perform navigation tasks such as making a U-turn, backing up and fine-tuning the direction of the wheelchair in a limited space. Subjects were asked to navigate through the course as fast as they could, while avoiding collisions.

ton33234 Tongue Controller Looks Promising For Paralyzed

Each subject operated the powered wheelchair using two different control strategies: discrete mode, which was designed for novice users, and continuous mode for more experienced users. In discrete mode, if the user issued the command to move forward and then wanted to turn right, the user would have to stop the wheelchair before issuing the command to turn right. The stop command was selected automatically when the tongue returned to its resting position, bringing the wheelchair to a standstill.

“Discrete mode is a safety feature particularly for novice users, but it reduces the agility of the wheelchair movement,” explained Ghovanloo. “In continuous mode, however, the user is allowed to steer the powered wheelchair to the left or right as it is moving forward and backward, thus making it possible to follow a curve.”

Each subject completed the course at least twice using each strategy while the researchers recorded the navigation time and number of collisions. Using discrete control, the average speed for the five subjects was 5.2 meters per minute and the average number of collisions was 1.8. Using continuous control, the average speed was 7.7 meters per minute and the average number of collisions was 2.5.

It’s been a while since we covered news about the tongue controller which enables quadriplegics the ability to operate wheelchairs and other devices by moving their tongues. The newest prototype of the Tongue Drive System makes use of a dental retainer with sensors to help control the system. tongue controlled wheelchair New Tongue Drive System Uses Dental Retainer to Operate WheelchairThe embedded sensors within the retainer track the movements of a small magnet attached to the tongue.

Problems related to using a headset as the magnet sensor in the earlier version of the system required the team to try a wireless dental retainer. The retainer is powered by a rechargeable lithium-ion battery and makes use of magnetic field sensors on the four corners of the device to track the magnet’s movements. The sensors transmit their information to an iPod or iPhone and special software enables the mobile device to control the movements of a cursor on a computer screen or to work as a substitute for a joystick in a powered wheelchair.

The Tongue Drive System can be made to interface with any standard electric wheelchair. Since the new version has an improved sensitivity, additional tongue movement commands can be programmed into the system. Earlier tests using the older version of the system have been done with 11 patients with high-level spinal cord injuries. These tests showed that after getting used to the device, the people in the study group were able to operate their wheelchairs and computer cursors faster and with more accuracy. The researchers expect even better results from the intraoral Tongue Drive System.

Source : http://gtresearchnews.gatech.edu/tonguedrive3/

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