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Virtual injuries, safer reality

Applying technologies that allow for ergonomic interventions much earlier in the virtual manufacturing design process prevent workers from being exposed to injury.


May 13, 2011
by Jim Potvin

Manufacturing environments exert physical demands that are strenuous and repetitive, often resulting in injuries. In Ontario from 1996 to 2004, there were more than 382,000 cases of such injuries accounting for costs of $12.3 billion. Ergonomics seeks to reduce the toll on muscles, joints and bones through effective workplace design.

As with any structure, human tissues are damaged when the demands placed on them exceed their capacity. Ergonomics uses science to determine thresholds for these demands.

Preventing strain injuries in manufacturing have been mostly reactive. Work tasks injure workers and only then are the jobs redesigned to remove the risk. This is an expensive way to discover poorly designed tasks and it results in unnecessary suffering.

But there are some companies taking a more proactive approach by applying sophisticated technologies that allow for ergonomic interventions much earlier in the virtual manufacturing design process that prevent workers from being exposed to the risk of injury. During virtual builds, digital human avatars are immersed into CAD/CAM environments to simulate interaction with machines, tools, parts and other workers long before the tasks exist in reality.

These avatars have become increasingly sophisticated in the past 20 years, now accurately representing females and males in all sizes. The skeletons represent real human motions and they have been designed to calculate human strength for a variety of postures.

A challenge when using this technology comes with accurately predicting the postures and motions that workers will eventually use on the real tasks. Ergonomic engineers manually manipulate digital avatars at computer workstations, or real humans can be immersed in virtual reality environments where they interact with CAD/CAM objects. This is similar to the motion-capture technology used to drive movements in video games and computer animation to make it look smooth and realistic.

Work simulation contributes in many ways to improved worker safety, increased efficiency and enhanced product quality. Avatars evaluate process sequencing, workplace layout and workstation design. For example, the insertion of a hose might be much easier for the worker, and take less time to perform if it’s completed before another part is placed in an obstructive way farther up the line. In the past, these issues wouldn’t have been known until production began. Now they can be flagged and fixed before a prototype is built.

Virtual reality also allows for many aspects of the human/task interface to be assessed early in the virtual build sequence. Different sizes of avatars are tested to ensure smaller workers can reach locations to perform their value-added tasks. Conversely, larger workers may have hand clearance issues and simulation will identify these cases.

Avatar software
The risk of injury is often dictated by the strength requirements of a task. Work simulation provides accurate estimates of the postures that will be required to perform work tasks, and digital avatar software calculates the proportion of the population that would have the strength to perform the task safely at the required frequencies. Tooling introduced to the simulations determines what’s best for each operation.

In Canada, researchers funded by the AUTO21 Networks of Centres of Excellence are improving and refining the efficacy of virtual reality, digital human models and work simulation for improving worker safety.

These studies, in collaboration with several industry partners, focus on increasing the understanding of tissues and how they are affected in the shoulder, forearm, hand and wrist – areas that contribute to a high percentage of assembly injuries. Research is also evaluating the validity of current virtual reality practices and processes. Recommendations have been made to further optimize the positive impact of these techniques.

Ford Motor Co., among others, has already demonstrated huge cost and quality benefits from using proactive ergonomics very early in the automotive manufacturing design process. However, many more companies and industries have yet to reap such rewards. While this technology is relatively new and still evolving, it shows great promise for improving worker safety while positively influencing high quality and profitable manufacturing.

Jim Potvin is a professor in Kinesiology at McMaster University and leader of the AUTO21 project, “Proactive automotive manufacturing ergonomics through improved work simulation and digital human modeling.” Visit www.auto21.ca.