  This paper presents design and experimental evaluations of an articulated
robotic limb called Capler-Leg. The key element of Capler-Leg is its
single-stage cable-pulley transmission combined with a high-gap radius motor.
Our cable-pulley system is designed to be as light-weight as possible and to
additionally serve as the primary cooling element, thus significantly
increasing the power density and efficiency of the overall system. The total
weight of active elements on the leg, i.e. the stators and the rotors,
contribute more than 60% of the total leg weight, which is an order of
magnitude higher than most existing robots. The resulting robotic leg has low
inertia, high torque transparency, low manufacturing cost, no backlash, and a
low number of parts. Capler-Leg system itself, serves as an experimental setup
for evaluating the proposed cable- pulley design in terms of robustness and
efficiency. A continuous jump experiment shows a remarkable 96.5 % recuperation
rate, measured at the battery output. This means that almost all the mechanical
energy output used during push-off returned back to the battery during
touch-down.
