Anthropometric criteria for the design of tractor cabs and protection frames

Abstract

Improved human – tractor interface designs, such as well-accommodated operator enclosures (i.e. cabs and protection frames) can enhance operator productivity, comfort and safety. This study investigated farm-worker anthropometry and determined the critical anthropometric measures and 3-D feature envelopes of body landmarks for the design of tractor operator enclosures. One hundred agriculture workers participated in the study. Their body size and shape information was registered, using a 3-D full-body laser scanner. Knee height (sitting) and another eight parameters were found to affect the cab-enclosure accommodation rating and multiple anthropometric dimensions interactively affected the steering wheel and gear-handle impediment. A principal component analysis has identified 15 representative human body models for digitally assessing tractor-cab accommodation. A set of centroid coordinates of 34 body landmarks and the 95% confidence semi-axis-length for each landmark location were developed to guide tractor designers in their placement of tractor control components in order to best accommodate the user population. Finally, the vertical clearance (90 cm) for agriculture tractor enclosure in the current SAE International J2194 standard appeared to be too short as compared to the 99th percentile sitting height of male farm workers in this study (100.6 cm) and in the 1994 National Health and Nutrition Examination Survey III database (99.9 cm) and of the male civilian population in the 2002 Civilian American and European Surface Anthropometric Resource database (100.4 cm).

Keywords:

• Tractor
• Anthropometry
• 3-D scans
• Accommodation
• Agriculture

Acknowledgments

The authors gratefully acknowledge the support of the entire research team, including Dr. Jin Guan, Darlene Weaver, Shirley Kristensen, Belva Hodge, Doug Ammons, John Powers, James Spahr and Paul Keane. Special appreciation is extended to Dr. Gary Rupp (Ford Inc.), Dr. Greg Zehner (US Air Force) and other anonymous reviewers for their insightful suggestions to the study report.