BlueBiped is a pair of robotic legs that walk "passively", that is to say, without using a power source other than gravity. Not surprisingly, they resemble human legs when in motion.
(Nagoya Institute of Technology video)
There are thighs and lower legs made out of aluminium that are the same length as their human counterparts, and ankles and knee joints for articulation, but… that’s it. No sensors, no computers, no “musculature” — the legs are completely passive, you just give them a push… and they carry on walking. As long as there’s a slight downwards slope, anyway — there has to be some source of energy, after all, and in this case it’s gravity.
BlueBiped uses the “principle of falling,” much in the same way that humans walk by falling forward. As long as the robot’s weight is pitched slightly forward, the momentum of each step is enough to throw it into another step, and so on.
The Nagoya Institute of Technology in Japan have also created a set of exoskeletal robotic legs that could be used by a human user to walk under minimal power.
I thought this story would make a good counterpart to my earlier article on A Prosthetic Arm That Feels; it turns out that Martin Caidin, author of the 1972 novel Cyborg, also wrote in detail about bionic legs which had a bit more pizzazz than BlueBiped:
They had created, lovingly, with infinite attention to detail, a bionics and electronics duplicate of what had been the legs of Steve Austin...