Lesher G W, Moulton B J, Higginbotham D J
Enkidu Research, Inc., Lockport, NY 14094, USA.
IEEE Trans Rehabil Eng. 1998 Dec;6(4):415-23. doi: 10.1109/86.736156.
Many persons with disabilities lack the fine motor coordination necessary to operate traditional keyboards. For these individuals, ambiguous (or reduced) keyboards offer an alternative access method. By placing multiple characters on each key, the size and accessibility of the individual keys can be enhanced without requiring a larger keyboard. Using statistical disambiguation algorithms to automatically interpret each keystroke, these systems can approach the keystroke efficiency (keystrokes per character) of conventional keyboards. Since the placement of characters on each key determines the effectiveness of these algorithms, several methods of optimizing keyboard arrangements have previously been proposed. This paper presents a new method for optimizing an arbitrary set of N characters over a collection of M keys. While earlier efforts relied upon approximations of keystroke efficiency, the proposed approach optimizes the arrangement under this exact performance measure. Applied to the canonical 26 characters on a nine-key "telephone keypad" problem, this method provides an improvement in efficiency of 2.5 percentage points over previously established layouts. Using only a minimum of calculations, the proposed technique operates quickly and efficiently, deriving optimal arrangements in a matter of seconds using a personal computer. The flexible method is applicable to arbitrary disambiguation algorithms, character sets, and languages.
许多残疾人缺乏操作传统键盘所需的精细运动协调能力。对于这些人来说，模糊（或缩减）键盘提供了一种替代的输入方法。通过在每个键上放置多个字符，可以在不增大键盘尺寸的情况下提高单个按键的大小和可操作性。利用统计消歧算法自动解释每次击键，这些系统能够接近传统键盘的击键效率（每个字符的击键次数）。由于每个键上字符的排列决定了这些算法的有效性，此前已经提出了几种优化键盘布局的方法。本文提出了一种在M个按键的集合上优化任意N个字符集的新方法。早期的方法依赖于击键效率的近似值，而本文提出的方法则在这一精确的性能指标下对布局进行优化。应用于九键“电话键盘”上的26个标准字符问题时，该方法比之前确定的布局在效率上提高了2.5个百分点。该方法仅需进行最少的计算，运行快速且高效，使用个人计算机在几秒钟内就能得出最优布局。这种灵活的方法适用于任意的消歧算法、字符集和语言。
