Computerized biomechanical models of the human musculoskeletal system now provide the means to evaluate the adverse effects and risks of heavy physical exertions. Such exertions are common in many jobs today, particularly in the Service Sector that employs over 68% of workers in the U.S. By using computerized simulations of human motions we are now able to predict many of the adverse musculoskeletal stresses during the design of future workplaces and vehicle interiors.
With the cost of musculoskeletal disorders exceeding $100 Billion annually, understanding the cause and prevention of these disorders is of National importance. The following are some of the research projects now being directed by Dr. Chaffin and his graduate students in this context:
Consultant to 25 different corporations, labor groups, and government agencies, including the Department of Labor, the Department of Health and Human Services, US Postal Service, Ford, United Auto Workers, General Motors, and Chrysler, on the increased costs and suffering associated with musculoskeletal disorders in industry. This work involves formal recommendations on the design of workplaces, equipment and tools, as well as presenting training programs for engineers and managers interested in the application of ergonomic principles to work design and evaluation.
Back in the early 1960s, Don Chaffin spent a summer as a quality control engineer in a ball bearing plant. Chaffin, then a freshly-minted General Motors Institute (now Kettering University) graduate, supervised 28 women who assembled tiny ball bearings for military guidance systems. Since a speck of dust could cause a bearing to fail inspection, the women worked in a sterile environment using magnifying glasses and microscopes. The pressure for precision was intense; the failure rate was high, and they frequently called Chaffin over to their workstations to point out things that made their jobs more difficult.
He noticed the toll that physical strain and fatigue took on the workers in the plant, and he started collecting data. The information he gathered hinted at trouble ahead.
It convinced Chaffin, today the R.G Snyder Distinguished University Professor emeritus of Industrial and Operations Engineering and a member of the National Academy of Engineering, that problems in the work environment – distraction, fatigue, confusion – were contributing to injuries and defective products.
That early work laid the foundation for a pioneering career in what’s become known as ergonomics – a discipline that resolves conflicts between a human and a system for the benefit of both. It blends engineering with psychology, biomechanics, epidemiology, and organizational structure. Good ergonomics result in healthy people working in an efficient system. It leads to fewer injuries, fewer mistakes, better productivity.
In 1979 Chaffin, then chair of the Industrial and Operations Engineering department, helped establish the university’s Center for Ergonomics, the first and largest center of its kind at the time. The research that he and his colleagues performed led the field into the mainstream and the one- and two-week training courses they held around the country educated thousands of doctors, engineers and safety professionals.
“It’s the way most companies run, nowadays,” he said.
Chaffin’s extensive work in understanding physical strains in the workplace have led some to call him the “Father of Occupational Biomechanics,” though he’s quick to clarify that a lot of people have contributed to the discipline. (That he co-authored one of the field’s definitive textbooks, Occupational Biomechanics does little to help him shed the title.)
Chaffin’s experience in factories – including time at a huge Western Electric plant where repetitive strain injuries hampered a third of the plant’s 20,000 workers – convinced him that engineers needed a broad body of knowledge to help them design healthier work settings.
As a PhD student at Michigan in the mid-1960s, Chaffin developed a model to predict the metabolic heat people generate when they work. When he returned to U-M as a faculty member in 1969 he led a team that developed an extensive strength database. He and his students then evolved that database into a software package – now licensed by the University and used by companies all over the world – that helps engineers design manual tasks based on a typical range of capabilities.
In 1998 Chaffin founded and directed the Human Motion Simulation (HuMoSim) Laboratory, which converts models of people’s natural motions into dynamic simulations that can be reproduced in computer-aided design programs.
Through the 1980s and 90s Chaffin and his colleagues were at the forefront of ergonomics research as the field became its own occupation – a common ground that both labor and management could agree upon.
According to the U.S. Department of Labor, workplace injury and illness cases in automotive manufacturing dropped from 238,800 in 1994 to 10,000 in 2013.
Today physical ergonomics has become a field of practice; the newest research frontiers in involve cognitive ergonomics – reducing mental stress and fatigue.
Every new work setting and every new piece of technology introduces potential unintended consequences for the people who use it. Cellphones and tablets demand our attention; our cars offer more entertainment and communication features, all potentially operated by someone driving 70 mph.
The future of ergonomics research, Chaffin says, is in helping people make good decisions quickly amid all the available data and the technology that delivers it.
“Psychology, biomechanics, computer science and engineering need to pull together to create ways to present data so the right data is ready at the right time,” he said. “It’s a very exciting era of ergonomics.”
Chaffin, D.B. Human Motion Simulation for Vehicle and Workplace Design. Human Factors and Ergonomics in Manufacturing, 17(5):475-484, 2007.
Hoffman, M.P. Reed, D.B. Chaffin. Predicting Force-Exertion Postures from Task Variables. Proceedings of SAE Digital Human Modeling for Design and Engineering Conference, 2007.
Holbein-Jenny, M.A., M. Redfern, Gottesman, D.B. Chaffin. Kinematics of Heelstrike During Walking and Carrying: Implications for Slip Resistance Testing. Ergonomics, 50(3):352-363, 2007.
Dickerson, C., D.B. Chaffin, R.E. Huges. A Mathematical Musculoskeletal Shoulder Model for Proactive Ergonomic Analysis. Computer Methods in Biomechanics and Biomedical Engineering, 10(6):389-400, 2007.
Dickerson, C., B.J. Martin, D.B. Chaffin. Predictors of Perceived Effort in the Shoulder During Load Transfer Tasks. Ergonomics, 50(7):1004-1016, 2007.
Hoffman, M.P. Reed, D.B. Chaffin. The Relationship between Hand Force Direction and Posture during Two-Handed Pushing Tasks. Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2007.
Seo, T.J. Armstrong, J.A. Ashton-Miller, D.B. Chaffin. The Effect of Torque Direction and Cylindrical Handle Diameter on the Coupling between the Hand and a Cylindrical Handle. Journal of Biomechanics, 40:3236-3243, 2007.
Seo, T.J. Armstrong, D.B. Chaffin, J.A. Ashton-Miller. Inward Torque and High-Friction Handles Can Reduce Required Muscle Efforts for Torque Generation. Human Factors, 50(1):37-48, 2008.
Seo, T.J. Armstrong, D.B. Chaffin, J.A. Ashton-Miller. The Effect of Handle Friction and Inward or Outward Torque on Maximum Axial Push Force. Human Factors, 50(2):227-236, 2008.
Park, W., Chaffin, D.B., Martin, B.J., Yoon, J. Memory-Based Human Motion Simulation for Computer-Aided Ergonomic Design. IEEE Transactions on Systems, Man, and Cybernetics, 38(3): 513-527, 2008.
Pope, M.H., J. Frymoyer, G.B.J. Andersson and D.B. Chaffin. Occupational Low Back Pain Assessment, Treatment and Prevention, Mosby-Year Book, Inc., St. Louis 1991.
Chaffin, D.B.. Digital Human Modeling for Vehicle and Workplace Design, SAE Bookstore, Warrendale, PA 2001.
Chaffin, D.B., G.B.J. Andersson and B.J. Martin.Occupational Biomechanics (4th Edition) J. Wiley & Sons, New York, NY 2006.
Delleman N, Haslegrave C, Chaffin D. (Eds.) Working Postures & Movements – Tools for Evaluation and Engineering , Taylor and Francis, 2004.