Development and testing of a wearable wrist-to-forearm posture measurement system for hand-tool design evaluation

This study reports on the development and testing of a wearable wrist-to-forearm angle-measurement system for flexion/extension and radial/ulnar deviation of the wrist, and pronation/supination of the forearm. The system is based on inertial sensors and a microcontroller mounted on a glove and a forearm pad. The developed system was tested through the comparison of two off-the-shelf screwdrivers, one long and one short. Twelve male subjects participated in a within-subject experimental design test and performed a horizontal and a vertical screwing task for each screwdriver. Results indicated that the use of a long screwdriver causes significantly higher ulnar deviation of the wrist in both set-ups, while the short screwdriver promotes higher wrist extension in both set-ups. Clarity of the obtained results indicates that the proposed system is adequate for ergonomics studies on hand-tool design evaluation, while it addresses common pitfalls of other motion-capture methods.