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Electrical and electronic engineering
Eye tracking is a well-established method of computer control for profoundly paralysed people (Anson et al., 2002). Cameras are commonly used to track eye movements (Morimoto et al., 2005) but one alternative is the bioelectrical signal known as the electrooculogram (EOG). There are some EOG mouse control systems that facilitate the use of GUI applications, but certain actions, which are straightforward using a conventional mouse, remain impossible. Unless the eyes are tracking a target, they move in saccades (jumps), making it impossible to voluntarily trace out smooth trajectories with one's gaze, as would be required to draw a smooth curve. The conventional paradigm for EOG mouse control maps horizontal and vertical angular displacement of the eyes onto the coordinates of the mouse pointer (Gips et al. and Estrany et al., 2008), while the head remains stationary. Reversing this paradigm, if the point of fixation remains unchanged, the EOG can measure head movement. The present system adopts this approach, mapping smooth, saccade-free head movement onto mouse pointer movement, while the gaze remains fixed on a point that is either stationary or moving smoothly (e.g. the mouse pointer). Because the eyes move in pursuit mode rather than in saccades, smooth mouse control is possible. Voltage drift, which arises due to changing electrode junction voltages, poses a serious problem for EOG-based mouse control. In this paper we show how an accelerometer can be used to mitigate the effect of voltage drift.
Keegan, J, Burke, E., Condron, J., Coyle, E.:On Improving Electrooculogram-based Computer Mouse Systems: the Accelerometer Trigger.Bioengineering In Ireland, January 28–29, 2011, Galway