Abstract:

In order to explore the effects of sway on keyboard input of operators in DCS and to reduce human errors, an experimental study was conducted under four sway conditions—static, low, moderate, and high. Operators' performance in numeric, alphabetic, and alphanumeric input tasks, as well as their subjective ratings, were measured. Statistical analyses were employed to examine the effects of sway and to compare performance differences across input types. The results show that sway has a significant main effect on keyboard input performance. Compared with the static, low, and moderate sway conditions, the input time and number of corrections for alphabetic and alphanumeric entries significantly increase under the high-sway condition, whereas the accuracy of numeric and alphanumeric inputs significantly decrease. Significant differences are also found among the three input types: numeric input achieves the highest accuracy and shortest completion time, while alphabetic input requires the longest time. Sway also significantly affects subjective evaluations. Under the high-sway condition, perceived input difficulty, physical discomfort, visual discomfort, and workload ratings are all significantly higher. Under low and moderate sway conditions, input performance and perceived difficulty are largely consistent with the static condition, whereas under moderate sway, the perceived difficulty and workload for alphabetic input are significantly higher than those under low and static conditions. Under high sway, overall input performance markedly declines, accompanied by pronounced increases in difficulty, discomfort, and workload.

Key words: sway conditions, digital control system (DCS), operator, keyboard input, performance, subjective ratings