Effects of two ergonomic aids on the usability of an in-line screwdriver

We assessed the effects of two ergonomic aids on the usability of an in-lin e screwdriver. The simple aids considered were a hand support and a sleeve which softened the handle. In an experiment, 15 subjects drove screws into horizontal plywood plates with four combinations of a screwdriver and an er gonomic aid. The activities of four forearm muscles (EMG) and the force act ing on the screw were measured. The subjects rated the properties of the to ols as regards physical exertion, the ease of taking hold of the tool, comf ort of the grip, and the surface texture. The hand support and the sleeve h ad positive effects on the subjective perception of exertion and the surfac e texture, respectively. Differences in EMG and thrust force along the shaf t of the screwdriver handle were found to be too small for reliable deducti ons in the effects of the ergonomic aids. (C) 2000 Elsevier Science Ltd. Al l rights reserved.