At Oregon State and Carnegie Mellon Universities folks are building robotic legs that recycle energy stored when the leg is bent, just like animals do. Apparently humans are able to naturally recycle about 40% of the energy in a springy step. If this can be accomplished in artificial legs, then the motors and batteries will not have to be quite as large and heavy, making life easier for developers and potential future users of the technologies, such as exoskeletons and other assistive devices.
Here’s a video from NewScientist demonstrating the robotic springy leg:
More from NewScientist…
Project page at Carnegie Mellon University: Electric Cable Differential Leg