US Patent 9283673 Fast runner limb articulation system

A robotic limb structure which is capable of achieving high speeds. In the context of a biped, the structure is used for a pair of hind limbs. The limb structure includes a primary driven link—such as a thigh pivoting about a hip joint in the case of a hind limb. Secondary links are pivotally connected to the primary driving link. Auxiliary links are provided to constrain the motion between the links. Elastic trim elements are also provided to define a “relaxed” state for the limb and to influence the resonance characteristics of the structure. The control system takes advantage of the resonant characteristics of the structure as a whole.