Case Study

Field Trials Demonstrate Potential Value of Repetitive Motion Exposure Assessment Tool

Published: May 4, 2009

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Researchers with Georgia Tech's Agricultural Technology Research Program (ATRP) in conjunction with member companies of the Georgia Poultry Federation have been working together to develop an instrument to assess the risk of musculoskeletal injury. The initial focus has centered on the cutting tasks associated with the deboning process and their impact on musculoskeletal activities of the upper and lower arm. The specific ergonomic factors related to these cutting tasks include grip force, posture, and repetition.

"The ultimate goals for this research program are to assist plants and ergonomists in developing effective worker rotation schemes and training programs for new and inexperienced workers to minimize the risk of injury," says Doug Britton, research engineer and project director.

To accomplish these goals, the research team recently modified a cutting edge measurement tool, developed several years ago by ATRP, known as EWAS or Ergonomic Work Assessment System. This new and improved version of the system uses biomechanical measurements and position-tracking technology to measure the fore- and upper-arm muscle stress/strain associated with the poultry deboning cutting tasks. A ShapeTape fiber optic position measurement system is integrated with EMG sensors and an instrumented knife, developed at the Liberty Mutual Research Institute for Safety, to collect data from workers on an actual processing line in a plant. As a worker wearing an arm strap cuts poultry, the aggregate data of the back and arm position, muscle response, and grip force is transmitted wirelessly to a laptop computer allowing researchers to study relationships among force, exertion, posture, and repetition. The information can be used both to boost work efficiency on the deboning line and to correct inefficient movements by workers performing the cutting task.

Researchers recently conducted an in-plant pilot test of the system with data being collected from five volunteer subjects that included both experienced and inexperienced workers as well as non-fatigued and fatigued workers. According to Britton, an initial analysis of the data reveals several interesting observations regarding worker actions associated with the wing cut.

• Experienced workers exhibit a larger yaw motion of the back in the coronal plane when compared with inexperienced workers.
• Experienced workers exhibit a much smoother cut trajectory in the z-plane when compared with inexperienced workers.
• Experienced workers exhibit less rotation or twist of the upper body in the transverse plane when compared with inexperienced workers.
• When experienced workers become fatigued, their work patterns tend to become more like those of the inexperienced workers.

While these are only preliminary results, Britton explains that they do indeed provide insight into some of the differences between experienced and inexperienced workers and fatigued and non-fatigued workers.
"Given that the sample of workers is relatively small, a larger study is being planned that should provide an even better insight into the musculoskeletal activities associated with doing these cutting tasks," adds Britton.
Researchers also anticipate that developments in this area will be expanded to include assessments of the back and other tasks within the poultry processing environment.