Dynamically Adjusting Touch Buttons
I describe here a simple technique that can be used by touch buttons (on a touch-screen interface) to improve, over time, the accuracy of the user touches.
Each button keeps track of the place where the user touch occurs. The touches which are close enough to the button centre are deemed sure touches, meaning that the button is pretty sure that the user wanted to touch this particular button and not a neighbouring one. For example, the button can use an embedded smaller circle or ellipse, called the sure area, and all touch that occurs within the sure area is a sure touch.
Each button averages all its sure touches that occur over time. When a certain number of such sure touches is accumulated, their average is compared with the ideal button center. If a systematic bias is detected (e.g. let’s say that the user generally touches with 3 pixels above the button center), the button records the bias and corrects it in future touches. (alternatively this can be seen as the button moving its center to the actual place where the sure touches occur in average).
The adjustment also affects the definition of future sure touches, as a touch is first corrected before being checked for happening within the sure area.
After the adjustment, the button continues to keep track of new sure touches as they occur, and to make new adjustments as needed.
This technique is most effective when every button keeps track of its own correction parameters. For example, a button which is located at the top of the screen may have a different bias (and thus need a different correction) than a button located at the bottom of the screen (or buttons located left - right may need different correction, etc).
This technique allows the interface to ‘learn’ over time the touch habits of a particular user (and to optimize itself for that user); but the interface is also able to adapt to a new user (if the device, for example, changes its owner).
For this technique to work, UI elements (such as buttons) must have access to touch events from outside their visual area on the screen. What the dynamic adaptation achieves is a separation and translation of the touch area of the button independently of its visual area.
The technique as described above supports the translation of the touch area, but can be easily extended to handle other transformations (such as dynamically growing the touch area of a button when the distribution of the touches shows too many touches close to its border, suggesting that the button is too small for the particular user).
When the touch area of buttons is segregated from their location (visual area) and is mobile (can move or grow/shrink), conflicts may appear between neighboring buttons. How to elegantly handle such ‘touch area conflicts’ is left as a thinking exercise to the reader or implementer.
August 1st, 2008 at 02:04
Wow you’ve thought about this
Great idea! I wonder how this would team up with human learning - the user and the phone would be learning each other at the same time! It could be bad if it was too exaggerated - say, if the phone moved the touch area it had learned from you at about the time that you learned that you have to get right on the button. It could be great 