ErgoHOWL

Quarter Four 2022

Wearable Sensor Technology in Ergonomics

Studying and understanding human biomechanics has always involved tons of math and measurements. In biomechanics labs across the world, researchers have used different types of wearable sensors to collect this information. Distances, accelerations, angles, and other factors are collected using high tech, and highly expensive, sensor technology. This allowed us to analyze ergonomic postures and movements in a laboratory setting but conducting field analysis remained a difficult task. Luckily that is changing. Wearable sensor technology is becoming smaller, less intrusive, and more cost effective.

Initially, when I say wearable sensor technology, you probably think about motion capture suits you see in the movies or bulky multi-sensor outfits where the user can hardly move. With new technology, that is hardly the case. You probably have a wearable sensor on your person as you are reading this article. Smart watches, exercise trackers, and even your cell phone can record and collect much of the data that previously was only available in the laboratory. Since we now have access to this data in real time, the question now is, “What do we do with it?”

Influence Safe Behaviors

Our main goal as safety and ergonomic professionals is to engineer out as much risk from a job as possible. Unfortunately, complete elimination of risk is not always feasible. Think about all the material handling tasks that you have at your facilities. Since many of those risks cannot be completely eliminated via engineering controls, we rely on our administrative controls. Most of us have gone through a safe lifting training and require our employees to do the same. Good handling techniques can reduce the risk of an injury, but we know that proper lifting/handling is not always done. This is an area where wearable sensors can shine.

When a high-risk movement or posture is observed by the sensor, it cues the user via real time auditory or haptic feedback. This allows the user to correct the action immediately, reducing the chance of a risky action. Most of the sensors on the market focus on the impacts on the back and will be able to alert the user to lumbar flexion, rotation, static postures, repetitive movements, and high-intensity movements. In addition to the back, there are senor systems that can also be used for the upper arms, lower arms/wrists, hips/pelvis, legs, and feet. Proprietary software and training are bundled with many of the sensor systems. To better improve the behavior of the users, an individualized dashboard is provided to the wearer. Here they are able to track their improvement and see where they might have an area for more training.

Worker feedback on the devices alerting them has been generally viewed as positive. A pilot study using 120 employees over a two-month period saw 83% of their employees improve their lifting techniques. A member of pilot program at a distribution center had this to say:

“The device I wore for the 10 days was great. In the beginning it would beep a lot but tapered off towards the end of the 10 days. I knew I was improving. It really did help me on how to bend properly and how to pick up things along with posture and twisting. It was good to see how well I did”.

Influence Safe Behaviors

In addition to providing feedback to your employees, these systems are used for conducting risk or ergonomic assessments. Today an ergonomic assessment typically requires trained and skilled practitioners. These can be an internal or external ergonomist, consultant, SME, or cross-functional ergonomics teams that have been trained and have developed unique skill sets to recognize, evaluate, & control ergonomic risks in the workplace.  Traditional assessment tools are observation-based and rely on handwritten notes and measurements. The accuracy of the measures can be subjective as they rely on measuring tapes, goniometers, force gauges, and dynamometers to estimate reaches, angles, and forces. In addition to these factors the assessments are time-consuming and can interrupt the worker that is being observed. Wearable sensors can mitigate many of these factors.

Wearables allow us to collect the needed assessment data with little to no intrusion on the user. The data can be more accurate, and we can collect a much larger sample. Previously we may have been able to view one or two employees over the course of one shift. Now we are able to collect data on the entire workforce over multiple days. As an ergonomist the data is great, and we can apply the correct tool for analysis. If you do not have ergonomic expertise at your facility, the sensors typically have built in analytics available. Many of the systems use traditional ergonomics analysis tools such as NIOSH Lifting Equations, Liberty Mutual Manual Material Handling Guidelines, RULA, REBA, and others. Proprietary assessment tools are also included with many of the systems, but we are unable to speak on the accuracy or efficacy of those assessment tools.

Conduct Ergonomic Risk Assessments

Before jumping in and buying a sensor for every employee in your facility, there are some factors to consider. In some case studies, employees would stop wearing the sensors after a week. Sometimes this was because they simply forgot them, or they interfered with their work. Because of this, many sensors have been modified to be attached to required PPE (hard hats, safety vests). Consider the work environment of the wearable. Will it interfere with any machinery or pose a snagging hazard? Each of the wearable sensors will have different capabilities. Do you just need postural data? What about static and repetitive actions? Do you need GPS data? What about environmental data like temperature, humidity, air quality, barometric pressure, and noise? Ensure that the tool you select will answer your ergonomic questions.

Currently, manufacturers of these sensors are working with their clients to provide internal case studies to review the efficacy of their product. Validation of the accuracy of some of the measures is still and ongoing task. To date we have yet to see a longitudinal study conducted by 3rd party like a university that shows long-term injury reduction or other metrics after introducing such tech. Hopefully that is underway, but we have yet to see it published in any type of peer-reviewed journal.

Remember that wearable sensors are not a magic bullet. They are a tool in your ergonomic toolbox. Ensure that the tool will analyze what is intended, will be accepted by your workforce, and is within your budget and available expertise. Regardless of what tool or vendor you choose to do business with, try before your buy.

The Value of Ergonomics

Workplace injuries are expensive for employers. According to the Liberty Mutual 2021 Workplace Safety Index, overexertion involving outside sources (handling objects), other exertion or bodily reactions (awkward postures) and repetitive movements cost businesses over 19.67 billion dollars in direct costs per year. Indirect costs impact employers even more, due to production losses, poor quality, training replacement workers, absenteeism, and facility and tooling changes.

According to the Liberty Mutual Research Institute for Safety, for every dollar invested in employee safety, there is a savings of between three and six dollars. Not only do these interventions reduce costs from accidents and injuries, and reduce training and maintenance costs, companies typically see significant improvements in worker productivity and job satisfaction, which reduce employee turnover and absenteeism.

In a 2014 study, the impact of ergonomics interventions resulted in the following payback periods:

  • Electronics Manufacturing: 0.5 weeks
  • Process Manufacturing: 1-18 weeks
  • Textile Manufacturing: 9.6 weeks
  • Office Work: 2 weeks

Additionally, productivity rose in a number of industries:

  • Valve and furniture manufacturing: 15%-20%
  • Call centers: 45%
  • Air handling unit manufacturing: 140%
  • Order picking in warehouses: 8.4%
  • Furniture manufacturing: 46%
  • Various manufacturing settings: 1.6% (average)

In a Washington State Department of Labor and Industries survey, ergonomics was shown to provide substantial benefits in a number of key areas:

  • 25% Increase in productivity
  • 58% Less absenteeism
  • 68% Savings in workers compensation costs
  • 75% Reduction in lost workdays
  • 59% Fewer work-related musculoskeletal disorders
  • 48% Lower turnover

Ergonomics not only provides a safer work environment, but also has been proven to provide a company with a return on investment that significantly impacts the bottom line.