Free software models how humans move

STANFORD (US) — An open source software application modeling human motion is helping medical professionals and bioengineers study, diagnose, and correct abnormalities in how people move.

In the future, OpenSim is expected to help determine whether a simple surgery to lengthen a specific muscle might help people with cerebral palsy; predict how simple changes in gait might reduce the incidence or severity of osteoarthritis; and help millions of people delay or avoid costly hip and knee replacements.

It may also help in the development of new, more sensitive prosthetics that are able to read and interpret electrical impulses to control the devices.


“OpenSim is out there and hundreds are downloading it every week,” says Jennifer Hicks, OpenSim’s project manager at Stanford University. “If each copy helps only one person, that’s helping a lot of people.”

“That’s the exciting thing about open source,” says Scott Delp, professor of bioengineering, mechanical engineering, and orthpaedic surgery. “By putting this powerful software in the hands of as many people as possible, we are setting in motion a self-perpetuating research ecosystem that will build upon itself to push the field forward.”

OpenSim will be on display as part of an exhibit exploring human movement at the  Leonardo, a science and technology museum in Salt Lake City, Utah.

The idea to unite museum and modeling software was the brainchild of Andy Anderson, a research assistant professor at the University of Utah School of Medicine who was a visiting scholar working with Delp and Hicks.

The Leonardo exhibit is really two exhibits in one. In the first section, visitors walk across a pressure-sensitive floor and are presented at the other side with color-coded print outs of their weight distribution, identifying even slight imbalances that might be putting undue stress on their limbs and joints.

Such stress can lead to pain or arthritis. Over a lifetime, even relatively minor abnormalities can compound until hip and knee replacement surgeries become necessary.

“This one is fun because people can insert various orthotics in their shoes and see how they affect their movement. It’s quite telling,” says Anderson.

The second exhibit is aimed at kids. To make their research more approachable for a younger audience, the OpenSim development team is creating an interactive soccer game. The real-world player adjusts the strength of two leg muscles on the simulated soccer player to generate the force necessary to kick a virtual ball into a virtual goal.

“This is a simplified version of our software, but by honing things down to just two muscles we can make the science of movement something kids can understand and have fun with,” says Hicks. “Most importantly, it is based on real physics and realistic physiology, so it really teaches as it entertains.

“Human movement is incredibly complex. The kids’ first instinct is to crank up the muscles to full strength, but this has unintended consequences, as the kids quickly learn.”

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