The Benefits of Sensorless Motion Capture for Ergonomics Assessments

Motion capture has been a gold standard for evaluating whole body movements in research labs for over 20 years. More recently, it has become feasible to apply this technology to job assessments in manufacturing environments. Originally, motion capture required the person to wear a large array of markers while the data was collected with multiple cameras to precisely record body movements. Now, the use of machine learning and artificial intelligence has reduced the need for multiple cameras and markers.  

The previous method of using sensors (or markers) in assessments: 

• required additional training in correctly placing those markers, 
• involved cleaning of markers between assessments, and 
• was a more invasive assessment technique with greater potential to impact how the operator acted while being assessed. 

Sensorless motion capture provides a level of accuracy in classifying posture ranges that is nearly the same as that obtained with markers, while requiring less time to complete, less training for users, and less interruption to the manufacturing process. Researchers benefit from the millimeter-level accuracy that sensors can provide, but that level of detail doesn’t add value to the typical ergonomics assessment. 

Sensorless Motion Capture vs. Observations

Ergonomics assessments in manufacturing and services environment rely heavily on observational techniques. The goal of ergonomics assessments outside of the research laboratory is typically to prioritize intervention efforts and quantify improvements. The accuracy of laboratory-based approaches has historically been replaced by observational assessments in manufacturing environments in order to attain sustainable cost:benefit ratios for ergonomics teams. 

Motion capture, using sensors or sensorless technology, provides considerably more accuracy than observations. Sensorless motion capture is somewhat more accurate at identifying postures than experienced ergonomists and substantially more accurate than less technical assessors. From a practical standpoint, this means that an inexperienced ergonomics team member using sensorless motion capture can assess a job with similar accuracy as an ergonomics specialist—this is its most important benefit. 

Sensorless Motion Capture Provides More Detail

No matter how experienced or dedicated an assessor may be, it is hard to collect accurate information about the percentage of time an operator spends in awkward postures. Although this is an important factor, most observational tools don’t include more than two levels of exposure for this variable. Motion capture provides the ability to accurately capture this data and apply multiple levels of exposure, and this added detail results in better prioritization of jobs. 

Sensorless Motion Capture Saves Time

It is surprising to many people that the largest benefit of motion capture isn’t the time savings. This method saves 10% to 15% per assessment, depending on aspects of the job like cycle time and variation in forces. The average time savings per assessment with motion capture is 11%, or an average of about 9 minutes per job assessment.  

Sensorless Motion Capture Saves Money

Sensorless motion capture saves considerably more money than it saves time, because it: 

• takes less time to learn how to conduct an ergonomics assessment, 
• requires less practice to complete an ergonomics assessment accurately, and 
• allows more people to accurately complete assessments, further reducing the cost per assessment.  

While the time savings per assessment may be relatively small, the cost savings per assessment is substantially higher, as a much wider range of people in the organization can accurately complete an assessment. The cost savings for an assessment can exceed 50%. What can’t be quantified is the value of replacing competing opinions with factual evidence. How much time has your ergonomics team wasted debating the risk scoring of a job? 

Summary

Although the greatest benefits of motion capture are its accuracy and savings, using motion capture technology also saves organizations more time. While the total amount of time savings is modest, the ability to have increased accuracy and detail combined, with even a small decrease in time required, is beneficial.  

Motion capture results in more accurate ergonomics assessments and less money spent by an organization. It requires less training and practice for users, and it allows a wider range of employees to complete accurate assessments, helping to improve the safety of all employees.  

VelocityEHS Industrial Ergonomics 

Learn more about our newest motion capture updates in VelocityEHS Industrial Ergonomics that enhance employee privacy and promote greater accessibility. Now you can block faces, blur backgrounds, and omit leg data to assess seat work tasks.