This robot has drop foot. It's flat-footed. The condition makes the robot more easily tripped. A seam in the carpet can do it.
What causes drop foot?
* nerve injuries
* brain or spinal disorders
* muscle disorders
* being a Boston Dynamics robot.
More information on drop foot here, description and treatments.
People walk by lifting their leg forward and lifting their toes so the step lands solidly on the heel. Forward momentum, body weight rolls over the foot lifting off the toes. So the heels of shoes are worn down before the lower soles, so that gait can be analyzed, pigeon toed, or out toeing, and inside the shoes, toe prints wear into the inside soles. So if you were to stick your hand in the shoe to feel the inside bottoms, you could feel the indentations worn down by the toes. Your toes grab as you walk like monkey hands.
People with drop foot lift their legs higher or swing their leg further outward in an arc.
My dad told me he bought us all shoes twice a year. I hadn't noticed that. All I ever noticed was, oh crap, shoe shopping again? GAWL!. Of all five kids, mine were noticeable because the heels of my shoes were worn down in the middle, the other kids either left or right. My mum told I walk like I have a board up my ass.
Actually, a teenaged male walked across the street in front of her car at a stop light and she said to me, "That's how you walk," and that guy walked like he had a board up his ass.
And I was made to be permanently self-conscious about how I walked thereafter.
But now my shoes wear down toe first an heels are not worn at all. And when I stick my hand inside to feel toe prints, there aren't any. It's like a brand new inner sole, while the outside is worn. Because now I walk like this robot. Except this robot is running.