While touch screen controllers are being introduced as components of modern flight deck instrumentation, they are constrained by the problems associated with inadvertent touch, which may be defined as any system detectable touch issued to the touch sensors without the pilot's operational consent. That is, a pilot may activate touch screen control buttons inadvertently because of turbulence, vibrations, or aspects of the pilot's physical and cognitive workload, resulting in possible system malfunction or operational error. For example, potential sources of inadvertent touches include accidental brush by a pilot's hand or other physical object while the pilot is not interacting with the touch screen controller; e.g. touch resulting when moving across the flight deck or involuntary movements (jerks) induced by turbulence. Accidental activation may also be caused by a pilot's non-interacting fingers or hand portions. Furthermore, environmental factors may also result in inadvertent touching depending on the touch technology employed; e.g. electromagnetic interference in the case of capacitive technologies, or insects, sunlight, pens, clipboards, etc., in the case of optical technologies. Apart from the above described side effects associated with significant control functions, activation of even less significant control functions degrades the overall functionality of touch screen interfaces.
One known approach for reducing inadvertent TSC touch involves estimating the intent of the user to activate a particular control button by tracking the user's gaze or head movement. This approach operates under the assumption that if the user is gazing or looking toward the TSC, then it is likely that the user is aware of the action being performed by the user's hand. Unfortunately, such systems do not differentiate between a control button that operates a significant avionics system (e.g. engaging the auto-throttle) and a control button that is associated with a less significant function (e.g. a camera video display). Simply stated, the significance of the functionality or system being impacted by an inadvertent TSC touch may range from a mere inconvenience to a possible safety issue. If a stringent eye gaze or head position tracking method is employed for highly significant TSC control buttons and control buttons of less significance, there will result unnecessary expense from a performance point of view. On the other hand, if a lenient eye gaze or head position tracking approach is taken for control buttons that operate significant and less significant functions, the operation of the significant functions could be compromised.
In view of the foregoing, it would be desirable to provide a system and method for reducing inadvertent touch on a TSC utilizing pilot or user gaze information to mitigate the inadvertent touch of a control button on a TSC considering the relative significance of the function or the avionics system operated by the control button. It would also be desirable to provide novel apparatus and methods for estimating the attention of the user or pilot using the point of eye gaze technique.