Abstract
In this case study, operators' cardiovascular activity was observed during the operation of modern forestry machinery. In addition to heart rate, power spectral analysis was used to indicate how the variance distributes as a function of frequency. As has been pointed out in previous studies, changes in relative power, especially at medium frequencies (MF), have been found to indicate the amount of mental workload. The results illustrated that operating a modern single-grip harvester causes relatively high mental workload. Moreover, significant differences in cardiovascular activity during different work tasks were observed.