Not true! For instance, here’s Pneu-Hound, a small robot dog created by a team of researchers at Osaka University.
What makes Pneu-Hound special is the first syllable in its name, which is short for “pneumatics,” or a system of engineering that deploys compressed air and/or other “inert gases.” It’s like hydraulics in a car, but with gas instead of liquid. Those tubes you see coming out of Pneu-Hound’s, uh, butt area are what power the robotic rapscallion’s artificial “air muscles.”
For comparison, Boston Dynamic’s recent robot pup, SpotMini, is all-electric. BD’s other, larger robots use hydraulic power, but SpotMini doesn’t require the substantial energy that comes from liquid power.
For the moment, however, pneumatics are much more common in location-fixed robots, like this humanoid robot that doubles as a mall info kiosk lady in Japan.
Pneu-Hound’s butt tubes are a good reason why.
This article originally appeared on Recode.net.