Roboticists worldwide are spending an obscene amount of time and effort trying to teach large humanoid robots how to not fall over. We rejoice every time there is even the smallest incremental bit of progress towards success, because not falling over is super hard, especially if you want your robot to be doing something useful. And even though some large humanoid robots can occasionally survive falling over, most of them don’t enjoy it very much.
Led by Kei Okada and Masayuki Inaba, a team from the University of Tokyo and Kawasaki Heavy Industries is working on their own life-sized humanoid robot, and they’ve come up with a new strategy for not worrying about falls: not worrying about falls. Instead, they’ve built their robot from the ground up with an armored structure that makes it totally okay with falling over and getting right back up again.
The concept behind Robust Humanoid Robot (RHP2) is, as the title of the paper suggests, that it should be able to work for a long time in hazardous situations like “a disaster site, a fire site or a wet environment.” The robot is tethered so that you don’t have to worry about power or connectivity, and since it can fall over and get up without any trouble, you won’t have to go rescue it and then waste time on repairs.
The fall protection system is designed to do three things: prevent direct mechanical breakage from contact with the ground, prevent indirect mechanical damage (like messed up joints and motors) that might otherwise be sustained during a fall, and prevent all of the fragile and expensive stuff like sensors and computers from fall damage. A lot of this is taken care of by an armored metal frame that encloses the entire robot, meaning that there are no weak points where environmental contact could cause damage. Places on the robot that are especially likely to experience stress (including knees, hands, chest, hips, elbows, and back) are particularly reinforced.
This version of RHP2 is powered by electric motors, although the researchers will eventually upgrade the whole system to hydraulic to give it more power. Rather than use conventional geared joint mechanisms, RHP2 uses linear actuators wherever possible because they’re much more robust. On top of all its metal armor, the robot can also put on different suits depending on what kind of environment it’ll be operating in:
The Robust Humanoid Platform (RHP) with a suit (top left), falling down (top right), and rendering of scenarios where the robot could be deployed (bottom).Image: University of Tokyo
RHP2 runs ROS and has a few autonomous behaviors, like being able to reposition its limbs during a fall and get itself standing again afterwards, but so far the researchers haven’t had a chance to emphasize practical, operational autonomy. Since the robot relies on that big tether anyway, it’s possible that realistic use-cases may involve telepresence, or DRC-style assistive telepresence.
It may be true that a robot that falls over all the time and just gets up again is not quite as elegant as a robot that doesn’t fall over at all, but we’re very far from the latter, and the former is ready to go right now. In the context of disaster relief, capable humanoid robots can’t come soon enough, so at least in the short term, a robust humanoid robot sounds like a good idea to us.