Wheelchair Control with Inductive Intra-Oral Tongue Interface for Individuals with Tetraplegia

High level spinal cord injury drastically reduces the quality of life of the injured person. Various systems attempted to interface the still intact or residual abilities following injury in various monomodal or multimodal designs to compensate for the highly affected mobility. An intra-oral inductive tongue computer interface (ITCI) has been designed to provide real-time discrete and proportional control for computers and assistive devices and to meet specific requirements for individuals with tetraplegia. Operation of the ITCI for wheelchair control was demonstrated with two participants with tetraplegia in a short-term training study. Additionally, two non-disabled individuals participated in the study. For each participant, the ability to drive a Permobil C500 with the ITCI was compared to that when driving the wheelchair with joystick (mouth-stick in one case) along two different lanes of 39 m, by reporting the speed along the lanes and the number of obstacles hit. The lanes consisted of 90°, 360°, and complex maneuver segments linked by linear segments. The ITCI featured a mouthpiece encapsulating two pads of inductive sensors, driving electronics, and battery. The mouthpiece was attached to the palate of the participant's oral cavity with dental retainers. A piercing-like activation unit was attached to the tongue. Data were transmitted wirelessly to a central unit that controlled the wheelchair through wired interface. Among all participants, mean speeds along lane A or B reached maximal values between 0.42 and 0.74 m/s when driving with the ITCI, representing 41 to 71% of that obtained when driving with the joystick.