Bionic Prototype Is Open for Business

The profusion of research projects in advanced prosthetics is both a blessing and a curse. Abundance maximizes the odds of success—the more arrows in the quiver, the better the chances of making a bull’s-eye. But it also hinders teamwork, as each researcher is shooting at the target from a slightly different angle with slightly different technology.

This inefficiency provided the spark for the Open Source Leg (OSL) initiative. Launched at the University of Michigan’s Robotics Institute in 2019, the OSL established a uniform hardware platform to promote collaboration among research units, bring competing devices into closer alignment, and create more of an apples-to-apples testing environment.

Nearly a dozen labs have implemented the OSL model so far, but many others lack the time and resources to follow suit. To attract more adherents, the Robotics Institute is partnering with Humotech (a Pennsylvania bioengineering company) to provide an off-the-shelf version of the OSL.

“By offering a preassembled version with professional support, we hope to improve access to this platform for studying the control of robotic prosthetic legs,” says Humotech CEO Josh Caputo. “We see many benefits to standardizing the hardware and software used by the research community.”

The original Open Source Leg was designed to be simple, affordable, and high performing. Its modular design can act as a knee, ankle, or both, with an onboard power supply and control electronics that allow it to be tested anywhere. Backed by major funding from the National Science Foundation, the leg was designed by two heavyweight bioengineers: the Robotics Institute’s Elliott Rouse and the Shirley Ryan AbilityLab’s Levi Hargrove.

The collaboration with Humotech puts additional firepower behind the OSL. “The translation of an open-source research prototype to a commercial product is rare for our field,” says Rouse, “but our partnership can continue to lower the barrier to research, speed technical advances, and positively impact lives.”

Researchers who want to build the OSL themselves will continue to have free access to the device’s parts list, assembly instructions, and programming specs. More info is available at

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