EYE GAZE TRACKING / ELECTROMYOGRAM COMPUTER CURSOR CONTROL SYSTEM FOR USERS WITH MOTOR DISABILITIES Armando Barreto†, Eyhab Al-Masri† and J. Gualberto Cremades‡ †Electrical & Computer Engineering Department, Florida International University Miami, Florida, 33174 ‡School of Human Performance and Leisure Sciences, Barry University Miami, Florida, 33161 ABSTRACT Eye Gaze Tracking (EGT) systems have been used to provide computer cursor control to individuals with motor disabilities (1). Involuntary movements of the eyes during a fixation limit the stability of this form of cursor control. An alternative system to step the cursor by detection of the contraction of selected facial muscles, through monitoring of the corresponding Electromyogram (EMG) signals, has been developed (2). The system presented here combines EGT and EMG monitoring to control the cursor, preserving the advantages and minimizing the shortcomings of each individual modality. Evaluation of the EGT/EMG prototype indicates a better performance than our previous EMG-only system and higher cursor stability than the EGT system. BACKGROUND Eye Gaze Tracking (EGT) systems, based on an infrared video camera that continuously captures images of the user’s eye, have been used to provide computer cursor control for individuals with motor disabilities who cannot use a standard mouse (1). In these systems the computer cursor tracks the point of gaze (POG) of the user, estimated by the EGT system. However, two significant limitations have been identified in these systems: a) The unavoidable shifts of the POG around a given fixation point result in a jittery screen cursor, and b) Emulation of mouse “clicks” by detection of special events in the EGT system (e.g., dwelling of the POG on a particular area of the screen or winking of the eye), tend to result in frequent artifactual clicks. Both these limitations prompted us to investigate alternative mechanisms to give cursor control capability to computer users with motor disabilities. Since many of these users retain control over their facial muscles, our group targeted the contraction of certain facial muscles not significantly involved in common activities (e.g., speech generation) as the form of user activity to drive an alternative cursor control interface. Our EMG-based cursor control system uses real-time spectral analysis of three EMG signals to command cursor steps in the LEFT, RIGHT, UP and DOWN directions. The EMG signals are obtained through surface electrodes placed on the left and right temples of the user, and on his/her forehead. A unilateral clenching of the left side of the mandible (by contraction of the left Temporalis muscle) is identified and converted by the system into a cursor step to the left. Similarly, right clenching of the mandible and raising or lowering the eyebrows result in cursor steps in the right, up and down directions, respectively. Detailed information on the design and evaluation of the EMG-only cursor control system has been presented elsewhere (2). In summary, the EMG-based system resulted in a steady cursor and a reliable clicking mechanism, allowing fine small adjustments in cursor position, but requiring larger time intervals for long excursions, due to the stepping nature of the approach used. This paper addresses the fusion of the EGT- and EMG- based cursor control systems into a “hybrid” unit, which switches effective modalities as needed.