OpenSim as a Platform for Improving Quantitative Ergonomic Assessments

Rocky Mountain Center for Occupational and Environmental Health (RMCOEH)

August 21, 2019 | 12 – 1 PM Pacific 

Presented By:  Andrew S Merryweather, PhD and Jonathan D. Mortensen (University of Utah)

Webinar Details


This webinar will provide a brief overview of OpenSim as a modeling platform to improve ergonomic risk assessment. Dr. Merryweather will demonstrate how OpenSim agrees with other analytical methods, specifically RULA, and present scenarios where OpenSim can be used to evaluate task level risk, including how to account for worker specific risk factors (i.e. previous injury, muscle weakness and fatigue) in conjunction with other physical risk factors (i.e. posture, force, repetition, duration). Finally, a summary of some limitations and future work using OpenSim for ergonomic risk assessment will be provided. 

Learning Objectives

At the completion of this webinar, participants will be able to:

  • Describe how OpenSim can provide additional insights into musculoskeletal disorder (MSD) risk

  • Discuss the relationship between RULA and OpenSim

  • Identify elements of MSD risk that are difficult to measure with less quantitative analytical methods

  • Review the limitations of using OpenSim for ergonomic analyses



Andrew S. Merryweather is director of the Ergonomics and Safety Program at the University of Utah and Associate Professor in the department of Mechanical Engineering. He is also an adjunct associate professor in the departments of Family and Preventative Medicine and Physical Therapy and Athletic Training. He teaches and directs research in the areas of biomechanics, human factors, musculoskeletal injury prevention, and human-system modeling. Dr. Merryweather obtained his Ph.D. degree in Mechanical Engineering at the University of Utah in 2008 as a NIOSH Trainee in Occupational Injury Prevention. A significant amount of his current research is related to wearable technology to determine occupational exposures and safe human robot interactions. To contribute to the body of knowledge in this field, Dr. Merryweather is engaged in team science and has worked with researchers from multiple disciplines including health sciences, school of medicine, college of nursing, computer science, mechanical engineering, industrial and systems engineering, and agricultural systems technology and education. He has received numerous honors & awards and was recognized as an outstanding teacher by the College of Engineering on multiple occasions. He was awarded along with his colleagues the 2017 IEA/Liberty Mutual Medal for original research titled “Relationships between job organizational factors, biomechanical and psychosocial exposures”.

Jonathan D.  Mortensen, PhD is currently an Exponent Associate in the Biomechanics practice. Jon recently received his Ph.D. from the University of Utah Department of Mechanical Engineering. Dr. Merryweather was Jon's academic advisor in the Ergonomic and Safety lab. During his time at the University of Utah, Jon was a National Institute of Occupational Safety and Health trainee at the Rocky Mountain Center for Occupational and Environmental Health. He has investigated the effects of various factors, including active neck muscles, on head injury metrics in various activities involving blunt force trauma, including American football. He has conducted studies on ergonomic risk, sports performance, and muscle control. Dr. Mortensen has developed and maintains an OpenSim model of the head and neck, which is freely available through

Special Thanks to Our ERC Partners at the RMCOEH: