Development of an effective computer interface for persons with mobility impairment

Many individuals are unable to type with a standard computer keyboard because of mobility limitations. Commercial hardware and software has been developed t o allow disabled users to enter text by various means, but a faster method which supports the use of standard commercial software packages would increase the potential for a person with limited motility t o use a computer productively. Visual Keyboard is a graphical representation of the keyboard that appears on the computer screen and allows the user t o type by clicking on the keys using a joystick, trackball, or the EyeMouse. Keystrokes can be sent t o Microsoft Windows applications that support dynamic data exchange (DDE). Visual Keyboard uses automatic capitialization, word prediction, and other features t o reduce the number of keystrokes required by more than 30% for some tasks. The interface allows disabled users t o work with the software most commonly used by businesses, and i t increases the efficiency of text entry by allowing random character access and by reducing the number of keystrokes required for a given task. INTRODUCTION Computers are useful for ’disabled individuals with limited motility because computers can be used with little physical exertion. However many Figure 1 Conceptual Diagram of Visual Keyboard 0-7803-1377-1/93 $3.00 01993 IEEE 1266 tasks such as word processing, using spread sheets, and computer programming require the ability to type with a keyboard. Commercial hardware and software have been developed t o allow disabled users t o enter text by various means including puff/sip devices, and switch devices triggered by eye lid, eye brow, or head movement [ 7 1. These devices typically operate using a cursor which scans letters, numbers, or menu choices. The user activates the switch t o stop the cursor and type that character. Greater typing speed would be possible if the user were able t o select from many keys at once, as is the case on a standard keyboard. A device which allows random character access would need to be usable by individuals with severe disabilities, such as quadriplegia, to replace the devices mentioned above. It should also be able to work with standard software packages t o allow easy exchange of files with others. METHODS Visual Keyboard is a graphical representation of a keyboard that appears in a window on the screen and allows the user t o type by clicking on the keys using a mouse, trackball, joystick, or EyeMouse. The keyboard window occupies the lower half of the screen, and the Microsoft Windows application in use occupies the upper half of the screen. Visual Keyboard can send alphanumeric keystrokes to Windows applications that support DDE (see Fig. 1). Individuals with the ability t o move their hands or arms may be able to use Visual Keyboard with a serial joystick or trackball. A large trackball is best for persons with mobility impairment. The EyeMouse is a device that tracks pupil movement by digital processing of a live video of the eye of the user. The EyeMouse generates “mickeys” to drive the cursor to the location where the user is looking on the screen, allowing severely disabled users to work with computers [2,3 1. a The main keyboard window of Visual Keyboard contains the alphabet, space bar, shift lock, return, delete, backspace, limited punctuation, and several keys that can be pressed to cause keypads to appear over the main keyboard window that can be