Effects of Keying Method, Image Preview and Work/Rest Schedule on Posture of the Remote Bar Coding Operators

Abstract

The main objectives of this study were to investigate the effects of different work/rest schedules, keying methods and preview conditions on postures preferred by the remote bar coding (RBC) operators, as well as on the patterns of postural changes over time, and to relate these to the perceived postural discomfort at work. Twelve operators (nine females and three males) were hired through a local employment service. A participation requirement was a minimum typing speed of 40 correct words per minute. Three factorial (2 × 2 × 3) design with replication was used. The experiment consisted of twelve scenarios utilizing three factors, i.e. 1) keying methodology (key all or key 5 digits only), 2) image preview (none or one), and 3) work/break schedule (50 minute/10 minute, 2 hour/15 minute, or flexible schedule). The data collection for biomechanical analysis of the RBC operators was performed using the video-recording technique. Assessment of the operator's postural discomfort was performed before the work started, immediately after each work period (during the break), and immediately after the task was completed. The results of postural discomfort analysis showed the significant effects of data collection time on all reported discomfort scores. The instruction to “key all” resulted in significantly higher wrist discomfort levels than the instruction “key 5 characters only.” The neck/head flexion was the lowest (mean = 30.2 degrees) for the flexible work/break schedule, and the highest (mean = 36.5 degrees) for the 50 minute work/10 minute break schedule. The preview condition resulted in smaller arm flexion (mean = 108.2 degrees) than the no preview condition (mean = 115.6 degrees). On average, the subjects used back support 34.7% of the time. When working with no image preview, the back rest was used 25% of the time. The back rest utilization increased for 50% of the time with the image preview, indicating more relaxed posture at work with the preview condition. The upper trunk angle (back inclination) assumed by the RBC operators was on average by 10 degrees greater than the angle preferred by the VDT operators.