Here is a robotic leg that can switch between a spring-suspended and unsuspended configuration to adapt to different tasks. Most legged robots use only a part of their available joint space. Fang Nan, Hendrik Kolvenbach and Marco Hutter have come up with a reconfigurable leg that increases overall efficiency.
The design is based on a parallel elastic element and a clutch mechanism on the knee joint. The above video shows it in action.
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