Relaxing stylus typing precision by geometric pattern matching

Abstract

Fitts' law models the inherent speed-accuracy trade-off constraint in stylus typing. Users attempting to go beyond the Fitts' law speed ceiling will tend to land the stylus outside the targeted key, resulting in erroneous words and increasing users' frustration. We propose a geometric pattern matching technique to overcome this problem. Our solution can be used either as an enhanced spell checker or as a way to enable users to escape the Fitts' law constraint in stylus typing, potentially resulting in higher text entry speeds than what is currently theoretically modeled. We view the hit points on a stylus keyboard as a high resolution geometric pattern. This pattern can be matched against patterns formed by the letter key center positions of legitimate words in a lexicon. We present the development and evaluation of an "elastic" stylus keyboard capable of correcting words even if the user misses all the intended keys, as long as the user's tapping pattern is close enough to the intended word. Copyright 2005 ACM.