title: Accuracy and repeatability of an inertial measurement unit system for field-based occupational studies.
abstract: The accuracy and repeatability of an inertial measurement unit (IMU) system for directly measuring trunk angular displacement and upper arm elevation were evaluated over eight hours (i) in comparison to a gold standard, optical motion capture (OMC) system in a laboratory setting, and (ii) during a field-based assessment of dairy parlour work. Sample-to-sample root mean square differences between the IMU and OMC system ranged from 4.1° to 6.6° for the trunk and 7.2°-12.1° for the upper arm depending on the processing method. Estimates of mean angular displacement and angular displacement variation (difference between the 90th and 10th percentiles of angular displacement) were observed to change <4.5° on average in the laboratory and <1.5° on average in the field per eight hours of data collection. Results suggest the IMU system may serve as an acceptable instrument for directly measuring trunk and upper arm postures in field-based occupational exposure assessment studies with long sampling durations. Practitioner Summary: Few studies have evaluated inertial measurement unit (IMU) systems in the field or over long sampling durations. Results of this study indicate that the IMU system evaluated has reasonably good accuracy and repeatability for use in a field setting over a long sampling duration.
authors.affiliation: a Department of Industrial and Systems Engineering , Auburn University , Auburn , AL , USA.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Schall
authors.affiliation: b Department of Occupational and Environmental Health , University of Iowa , Iowa City , IA , USA.
authors.forename: Nathan B
authors.initials: NB
authors.lastname: Fethke
authors.affiliation: b Department of Occupational and Environmental Health , University of Iowa , Iowa City , IA , USA.
authors.forename: Howard
authors.initials: H
authors.lastname: Chen
authors.affiliation: c Department of Kinesiology, Health and Nutrition , University of Texas at San Antonio , San Antonio , TX , USA.
authors.forename: Sakiko
authors.initials: S
authors.lastname: Oyama
authors.affiliation: d Department of Epidemiology, Human Genetics and Environmental Sciences , University of Texas School of Public Health , San Antonio , TX , USA.
authors.forename: David I
authors.initials: DI
authors.lastname: Douphrate
mesh_terms: D000328:Adult; D001132:Arm; D001696:Biomechanical Phenomena; D003612:Dairying; D006804:Ergonomics; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D016273:Occupational Exposure; D011187:Posture; D015203:Reproducibility of Results; D060726:Torso; D055815:Young Adult
keywords: Ergonomics tools and methods; agriculture ergonomics; back pain; musculoskeletal disorders; upper limb disorders