Since bipedal robots took their first steps, the majority
has been designed with the same basic joint/actuator configuration in their
legs. This design, based on a simplified human leg, uses just six motors (three
for the hip, one for the knee, and two for the ankle), and though it proved
successful, it has also shown several limitations over the last 25 years. Now
researchers at the Humanoid Robotics Institute at Waseda University (the
birthplace of the first real humanoid robots) have set out to reinvent the
wheel, er, the leg, by developing an entirely new shank that more closely
replicates human walking.