Informatics in Medicine Unlocked (Jan 2020)
Addressing the eye fixation problem in gaze tracking for human computer interface using the vestibulo-ocular reflex
Abstract
The characteristics of smooth versus saccadic eye movement tracking were compared for the purpose of human-computer interface. The study was performed by implementing a custom head-mounted system to track smooth eye movements for control of a mouse cursor. The system comprises a head-mounted infrared camera, an infrared light source, and a computer. Software-based image processing techniques, implemented in Microsoft Visual Studio, OpenCV, and Pupil, detect the pupil position and direction of pupil movement in near real-time. The identified direction is used to determine the desired positioning of the cursor, and the cursor moves towards the target. Two users participated in tests to quantify the differences between incremental tracking of smooth eye movement resulting from the vestibulo-ocular Reflex versus step-change tracking of saccadic eye movement. Tracking smooth eye movements was greater than four times more accurate than tracking saccadic eye movements, with an average position resolution of 0.80 cm away from the target. In contrast, tracking saccadic eye movements was measured with an average position resolution of 3.21 cm. Using the incremental tracking of smooth eye movements, the users were able to place the cursor within a 9 × 9 pixel square 90% of the time. However, when using the step change tracking of saccadic eye movements, the users were unable to position the cursor within the 9 × 9 pixel target. The average time for the incremental tracking of smooth eye movements to track a target was 6.45 s, whereas for the step change tracking of saccadic eye movements, it was 2.61 s. The smooth eye tracking system, while substantially slower than saccadic eye movement tracking, enabled more predictable, reliable, precise, and accurate control of the mouse cursor.
