Details on the design and clinical tests of an open-source bionic leg are now freely available online, so that researchers can hopefully create and test safe and useful new prosthetics.

Bionic knees, ankles and legs under development worldwide to help patients walk are equipped with electric motors. Getting the most from such powered prosthetics requires safe and reliable control systems that can account for many different types of motion: for example, shifting from striding on level ground to walking up or down ramps or stairs.

However, developing such control systems has proven difficult. “The challenge stems from the fact that these limbs support a person’s body weight,” says Elliott Rouse, a biomedical engineer and director of the neurobionics lab at the University of Michigan, Ann Arbor. “If it makes a mistake, a person can fall and get seriously injured. That’s a really high burden on a control system, in addition to trying to have it help people with activities in their daily life.”