Operator state includes operator utilization ratio, operator skill level, and operator performance.
The relation of operator utilization ratio and operator performance obeys the Yerkes-Dodson law , which is shown in Figure 1.
If the initial operator utilization ratio is [x.sub.0] [member of] [[x.sub.min], [x.sub.max]], the work time is t and the rest time after the task is r.
The evolution of operator utilization ratio with work time and rest time is shown in Figure 2.
where [mathematical expression not reproducible] are the bounds of operator utilization ratio, and t, r are N-vectors of [t.sub.j], [r.sub.j], which represent work time and rest time, respectively.
This is reflected in a reduction in the number of conveyor stops, a reduction in the instances the operator moves outside of the spray booth, and a reduction in the operator utilization. Opportunities to improve upon these results will be explored further.
Scenario 4 results show a reduction in operator utilization and that the operator never exceeded the workstation limits.