Evaluating the effects of activation mode, torque and horizontal operating distance on hand-arm response while operating pneumatic screwdrivers

摘要

The objective of this study is to evaluate the influences of activation mode, torque and horizontal operating distance on hand-arm response while operating in-line pneumatic screwdrivers. Hand-arm response was investigated in terms of finger force exertion, flexor digitorum electromyography, and hand-transmitted vibration. Two activation modes (push-to-start, and trigger-to-start), two torque levels (low, and high) and three horizontal operating distance (far, middle, and near) were evaluated. Thirteen healthy male subjects drove screws into an iron plate with pre-tapped screw holes using in-line pneumatic screwdrivers in randomly ordered experimental conditions. The results indicate that the use of push-to-start mode, not only required a greater holding force involving forearm muscular exertion and middle, ring and small finger forces, but also incurred a greater hand-transmitted vibration than the use of trigger-to-start mode. Higher torque caused a greater hand-transmitted vibration and required a firmer grip than lower torque. A middle distance level (18-30 cm away from the table edge) is recommended as it is found to have the least hand-transmitted vibration and requires less finger force exertion.