Single mirror tracking system for free-head video-based eye-gaze detection method

Abstract

The single rotation mirror system was designed for the development of the free-head video-based eye-gaze detection device used on communicators for the physically disadvantaged. In a previous study, the camera with the zoom lens rotated to direct its shooting area toward the eye. However, a better tracking system using a single mirror was expected. In the present study, the mirror was rotated two-dimensionally by a pair of servomotors through the lever crank mechanism. The image rotation owing to the mirror was compensated. The response of the mirror rotation system was much better than that of the camera rotation system. The eye-gaze point was determined from the eye position in space and the eye-gaze direction relative to the camera axis. The eye position was estimated using the mirror angle and the distance from the mirror rotation center to the eye, which was measured by the ultrasonic distance meter. The eye-gaze direction was estimated using the relative positions between the pupil and corneal reflection images, which were obtained using the real time image processor. Eye-gaze detection was extremely precise under the head-fixed conditions. Under the head-unfixed condition, however, the improvement of the ultrasonic distance meter or the arrangement of the mirror and menu screen relative to the head was expected.