The mental workload of harvester operators working in steep terrain conditions

Abstract

The use of modern multi-functional forestry machines has already been associated with central nervous system fatigue induced by high mental workload. As these machines are being used under increasingly difficult terrain conditions, further knowledge is required on the expected aggravation of operators’ mental workload, so that suitable work/rest schedules can be developed. Within such a context, the aim of this study was to gauge aggravations of mental workload derived from increasing slope gradient. Measurements of eye activity were obtained from a representative harvester operator working in corridors with the following mean inclinations: 9%, 23% and 47%. The duration, frequency and trajectory of eye movements were used to determine the harvester operator’s mental workload, on the assumption that worsening work conditions would be reflected by increased eyeball activity. The number of fixations during the performance of all tasks increased with the increasing slope gradient. Similarly, fixation duration increased with slope gradient. The mean duration of saccades when working on a 23% slope was 5% shorter compared to work under a 9% gradient. A further significant shortening of saccade duration (~22%) occurred when working on a 47% slope. The good match between eye activity cycles and work cycles, visible especially on steep slopes, indicates that mental workload is related to work conditions. Overall, operating a forest harvester on steep slopes results in a greatly increased mental workload and calls for suitable rest schedules.

Soil Disturbance Induced by Silvicultural Treatment in Chestnut (Castanea sativa Mill.) Coppice and Post-Disturbance Recovery

“…In fact, the slope gradient recorded in all sites was close to the limit for the use of ground-based equipment [34]: yet, Italian loggers often push their equipment close to its mobility limits, as already shown in recent studies that provide good witness to the use of forestry equipment on slopes close to 50% [35]. Farm tractors do not have such a good mobility as purpose-built forestry machines, but both tractors used in the study were equipped with a winch and they actually travelled only on the gentler areas, reaching trees laying on the steepest one using their winch [36].…”

Perception of the Harvester Operator’s Working Environment in Windthrow Stands

“…These probably occurred while maneuvering the machine and the harvester head for the purpose of allowing trouble-free and safe cutting of difficult-to-reach windthrown trees. Very similar results were obtained by Szewczyk et al [42], who analysed the work of a harvester operator on steep slopes: performing tasks in difficult terrain also involved fixations that were longer and had greater variability of duration than recorded for the same work and operator on gentle terrain. In another similar experiment, Häggström et al [38] compared the fixation times of a harvester operator working in a thinning and a mature stand.…”

“…The visual standard for the cognition of reality, namely eye tracking, is often used in neurobiology, psychology, marketing and computer science [40,41]. In forestry, the eye tracking study technique has been introduced in the last few years only [38,42]. Among other things, such studies probe the significance of recognising objects, planning tasks and establishing priorities, as well as top-down and bottom-up cognitive processes [43].…”

Estimation of Productivity and Costs of Using a Track Mini-Harvester with a Stroke Head for the First Commercial Thinning of a Scots Pine Stand

“…Several authors pointed out that thinning young stands presents several dilemmas, including high operational costs, frequency of invasive trips involving various kinds of field machinery, tree damage [13,14], and mental stress on the harvester operator [15][16][17]. To improve its efficiency, new and more effective methods for harvesting are being sought [18,19].…”