Development of a Test Battery for Fatigue Assessment of Agriculture Seating Systems: A Laboratory and Field Study

The objective of this project was to evaluate a battery of tests that could be used to assess fatigue development in the long-duration, seated operation of farming machinery. A battery of eight tests that had been previously used to assess aspects of human fatigue were assembled and human subject testing procedures (six participants in a laboratory study, eight in a field study) were employed to identify those tests that were sensitive to fatigue development in this context. In the laboratory study, participants maintained a seated posture for a period of 2 hours and experienced a controlled seat motion profile consistent with that of farm machinery working in a moderately rough field, while the field study participants experienced an 8-10 h ground preparation (heavy tillage with chisel plow) workday. The battery of tests considered included physiological assessments, human performance assessments, and subjective assessments. TIME was the independent variable. The non-parametric Kruskal-Wallis test was performed to assess the effects of TIME. Subjective assessments (Swedish Occupational Fatigue Inventory and Body Part Discomfort) had the strongest relationship with TIME, while two physiological assessments (heart rate and heart rate variability) were also shown to be affected by TIME. Subjective assessments were the strongest measures and objective measures heart rate and heart rate variability were effective at showing fatigue of the seated machinery operators. Human performance assessment approaches were not found to be predictors of fatigue of the seated operator.