A SYSTEM FOR EVALUATING THE EFFECT OF KEYBOARD DESIGN ON FORCE, POSTURE, COMFORT, AND PRODUCTIVITY

The purpose of this study was to develop a system to determine the eff ectiveness of an alternative keyboard design which aimed to reduce fin gertip force and awkward wrist postures. A prototype alphanumeric keyb oard, adjustable in four ways, was developed for this study. Four meas urements were chosen to determine the effectiveness of each keyboard c onfiguration: fingertip impact force; wrist position; productivity; an d comfort and ease of use. Fingertip force was measured using instrume nted keys that had strain gauges located between the key cap and the k ey switch. Wrist position was measured using electronic goniometers at tached to the forearms and hands of the test subjects. A computer prog ram was developed to measure productivity, and a questionnaire based o n the Borg rating scale was developed to measure comfort and ease of u se. The system was tested to ensure its accuracy. Linearity, repeatabi lity, strike position sensitivity, and natural frequency of the instru mented keycap assembly were assessed. Output of the electric goniomete rs was compared with readings on a manual goniometer to ensure the for mer's accuracy over the range of wrist angles expected during keyboard operations. Results of the validation indicated that the system is ca pable of measuring fingertip force and wrist angle accurately and repe atably. The system described in this paper is the first one that measu res fingertip force, wrist position, productivity, and comfort and eas e of use simultaneously.