Usability Validation of an Ergonomic Inward Directional Screwdriver for Enhanced Musculoskeletal Comfort

Previous studies suggested that the use of inward torque direction in hand-related manual activities not only increases the total normal force and torque capacity but also reduces grip force. This means lesser effort is required to perform the task, which prevents overexertion and hand injuries. Manual screwdrivers are the most common hand tools used in the industry and daily life. However, due to the difficulty users face when unfastening screws, it can also be a hand tool that potentially leads to the development of cumulative trauma disorders. In this study, 50 subjects participated in a psychophysical testing of an ergonomic inward directional screwdriver and a normal manual screwdriver. The comparative study involved the perceptions of grip, comfort and ease-of-twist for both normal and ergonomic manual screwdrivers. The data was analysed using the analysis of variance via Minitab 16. The results showed that grip, comfort and ease-of-twist are significantly affected by torque direction and ergonomics features. Further observations on participant justifications also suggested that participants rated the inward screwdriver as a better tool to be used compared to the normal screwdriver.