An ergonomic design and performance evaluation of handy scanners by males

This paper describes the results of an investigation of the difference in performance, posture used, strain on forearm musculature, and subjective ratings of three handy scanners (models A, B and C). Both models A and B were scanners on the market. Model C was developed for validation. The gripping posture of the three models is distinct both in the anatomical and functional sense. Work with model A requires a thumb-forefinger side grip which induces an ulnar deviation angle; work with model B requires a thumb-finger grip; work with model C requires a thumb-finger-palmar grip. Performance evaluation of scanner models A, B and C on different scanning tasks (with and without stitch) using different resolution modes (100 and 400 dpi), indicated that using the proposed model C resulted in a 13% higher success rate, a 14% shorter completion time, the smallest self-selected working area, least strain on the forearm muscles, and highest subjective ratings among the three. Model C appeared to provide the greatest opportunity for delicate adjustments of posture in response to the activity of the skin receptors, justifying the ergonomic input into the design.