No, these robotic legs aren't fooling anyone into thinking they're human, but researchers from the University of Arizona say that the legs are "the first to fully model walking in a biologically accurate manner" based on a bio-inspired combination of neural architecture, musculoskeletal architecture, and sensory feedback.
Not bad, right? Not perfect, but certainly not that ASIMO-style scared-of-falling robotic gait that we're used to.
There are three reasons why this robot exhibits such a human-like gait. First, it's got a very similar musculoskeletal system to ours, with movement driven by artificial muscles and tendons consisting of Kevlar straps and servo motors. Second, the robot uses a variety of sensors to provide continuous feedback about ground contact and foot pressure, muscle stretch and limb loading, and hip position, all of which is used to dynamically adjust the gait. Third, the movement of the robot is controlled at a relatively high level by a "central pattern generator" that mimics a cluster of nerves in a human spinal cord.
The central pattern generator (CPG) is the thing that lets us walk without having to think about walking, and it works the same way in the robot as it does in humans, by taking sensory feedback and using it to adjust the rhythm of the walking cycle. The simplest walking pattern that the CPG can create relies on just two neurons (virtual neurons, in this case) firing alternately. The researchers hypothesize that this is how babies first learn to walk, citing the fact that babies have been seen to exhibit a simple walking pattern when placed on a treadmill (!) even before they can walk on their own. After this initial simplistic gait is developed, more neurons get involved to form a more complex network that can produce a variety of gaits.
From the sound of things, this research isn't really intended to help robots walk better, but rather it's a way of "investigating the neurophysiological processes underlying walking in humans and animals." Well, that's cool, we won't judge, at least not as long as we keep getting to watch these robotic legs walking around human-style. Just one thing: No more babies on treadmills!