Siemens’s product life-cycle management software shows how certain tasks — turning a wrench, for instance — might affect a worker’s body, especially their joints. In this screenshot, a female avatar named “Jill” works on assembling a Ford Focus. (Courtesy of Siemens)

A few years ago, employees at a Ford auto plant in Michigan complained that installing a new wheel rim was hurting their backs.

Assembly-floor managers assumed that it was because the new rims were slightly heavier than an older model that employees were used to. Managers requested a new piece of equipment, called an articulating arm, that would attach rims to wheels automatically.

Before making the switch, Ford’s ergonomics team created virtual representations of the employees — called “avatars” — to assess whether articulating arms, which are expensive and can slow production, were necessary. Maybe, Ford thought, they could tweak the assembly process to favor physical movements that put less strain on employees’ backs.

Ford has been using Siemens’s product life-cycle management software to solve this and similar problems by modeling the manufacturing process’s effects on individual employees. The software shows how much stress is applied to each avatar’s joints or how much their spines compress when they perform certain motions — turning a wrench or reaching for a part stored high up, for instance.

Siemens acquired the technology in 1999 from a company spun off from the University of Pennsylvania. Since then, scientists at Siemens, with help from a research group at the University of Michigan, have evolved the avatars from basic stick figures, called Jack and Jill, to three-dimensional, customizable figures. Ford’s software package includes avatars tailored to the characteristics of Ford employees in various geographic regions. For example, in simulations of their Asia-Pacific plants, avatars are, on average, smaller than those in North American ones.

At the Michigan plant, Ford’s ergonomics team used the software to create a visual representation of the assembly floor, populated with North American avatars. They simulated the motion of rim installation and saw that bending down to pick up the rim strained the avatar’s back. But if they moved the pallets of rims to the side of an employee’s work station and gave avatars more room to rotate their bodies, the strain was reduced, said Allison Stephens, a technical specialist at Ford’s ergonomics lab.

Ford rearranged the assembly floor and stopped hearing complaints, Stephens said.

The company has been investing in this technology to better understand employee behavior, Stephens said. When they’re reaching in to assemble an engine, do they need to lean on the hood of the car? Do they bend forward or at the knees, potentially straining them?

The software is just as important in pre-production planning, Stephens said. “My deliverables are to look at the avatar early in the [car] design phase, and make a good plan [for assembly] when we go to production,” she said.

For instance, she said, “we’ve been able to look at our virtual series and virtual evaluation to show that it’s really inefficient for a person to do the extreme bend-and-reach” motion.

The ergonomics team also discovered, after using avatars to simulate assembly of a pre-production engine, that an engine hose with a push lock was straining employees more than a click-connect one would, and the product design team modified the assembly process.

“In years past, you’d have to learn from your experience,” she said.

The software is still evolving, she said. It only recently began reflecting the strain applied to a human wrist after performing a highly repetitive task. Ford has also been working with Siemens to more accurately simulate realistic posture, which could affect a person’s ability to perform a task. The two companies meet almost weekly to discuss potential improvements in the software.

Stephens said the software should not be used as a substitute for actually talking to employees about how the job affects their bodies.

“The emphasis is if I’ve already got the job in place, . . . then we tend to go out to the plant floor and evaluate on the floor.”