Tracking tongue movements for environment control using particle swarm optimization

We have developed a magnetic localization technique to accurately track 3-D tongue movements in the oral cavity and use this information to discern user´s intention. This method will be used in an unobtrusive, wireless magnetic tongue-computer interface, know as tongue drive, to provide people with severe disabilities with computer access and proportional control over their environments. A small permanent magnet secured on the tongue by implantation, piercing, or adhesives, is utilized as a tracer. The magnetic field variations due to tongue movements are detected by three 3-D magneto-inductive sensor modules and wirelessly transmitted to a computer to be translated into user-defined commands. The tracer is modeled as a magnetic dipole, which position and orientation are estimated using particle swarm optimization (PSO) algorithm. Simulation and experimental results show that using this method we can localize the tracer inside the mouth cavity every 0.2 s with 1 mm and 2deg resolution in position and orientation, respectively.