Japanese Humanoid Robot Can Keep Its Balance After Getting Kicked

University of Tokyo researchers used kicks, knee strikes, and shoves to test their new robotic legs

2 min read
Japanese Humanoid Robot Can Keep Its Balance After Getting Kicked

HRP3L-JSK Japanese humanoid robot getting kicked

For some reason, roboticists seem to enjoy testing their creations by kicking them, punching them, shovingthem, and even striking them with baseball bats and heavy pendulums. All in the name of science, of course. It wasn't different with this Japanese pair of robot legs, which as you can see from the photo above, is about to get kicked in the gut.

If we want robots that can do chores around the house, care for the elderly, or (if you're a DARPA program manager) drive trucks and crash through walls, then we need robots with actuators that are both fast and strong. The problem is actuators based on electrical motors can only deliver a limited amount of power, and the alternative, hydraulics, requires bulky pumps and can be difficult to control.

Junichi Urata and his colleagues at the University of Tokyo's JSK Lab, led by Professor Masayuki Inaba, are working on a possible solution. They've developed a high-torque, high-speed robotic leg based on a novel electrical actuation system. Their robot uses high-voltage and high-current liquid-cooled motor drivers that get their power from a 13.5-farad capacitor system. Why a capacitor? Because it can supply lots of current very fast and reliably, something that batteries are not good at. The researchers modified an existing HRP3L, developed by Kawada Industries, to create their robot, which they call HRP3L-JSK [pictured below].

Thanks to the capacitor-powered motor drivers, the robot's Maxon 200-watt brushless motors (modified to be liquid-cooled) can achieve instantaneous speeds of over 1000 degrees per second and 350 Nm of torque on the robot's knee joint. This capability allows the 53-kg robot to react to disturbances (in its case, kicks, knee strikes, and other abuse from researchers) and even jump 44 centimeters off the ground (though the landing part will need work). Watch:

The robot relies on a new balance control system that detects disturbances and computes 170 foot placement possibilities in 1 millisecond, choosing the best candidate to keep the robot from falling. The new method is a collaboration between the JSK team and researchers from Japan's National Institute of Advanced Industrial Science and Technology (AIST).

Urata, who recently received a PhD degree for his HRP3L-JSK work, now has his eyes on the DARPA Robotics Challenge. He's starting to organize a team to add manipulation arms and more sensors to the HRP3L-JSK lower-body. Will their fully electrical robot be able to perform all the tasks DARPA has conceived for the challenge? DARPA, for its part, has chosen a Boston Dynamics humanoid powered by hydraulic systems as the official hardware platform (to be used by teams that don't want, or can't afford, to develop their own robot). As more teams join the competition, it will be interesting to see what kind of actuation system they choose. Electrical or hydraulics: which will prevail?

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An illustration of a woman making a salad with robotic arms around her holding vegetables and other salad ingredients.
Dan Page

By 2050, the global population aged 65 or more will be nearly double what it is today. The number of people over the age of 80 will triple, approaching half a billion. Supporting an aging population is a worldwide concern, but this demographic shift is especially pronounced in Japan, where more than a third of Japanese will be 65 or older by midcentury.

Toyota Research Institute (TRI), which was established by Toyota Motor Corp. in 2015 to explore autonomous cars, robotics, and “human amplification technologies,” has also been focusing a significant portion of its research on ways to help older people maintain their health, happiness, and independence as long as possible. While an important goal in itself, improving self-sufficiency for the elderly also reduces the amount of support they need from society more broadly. And without technological help, sustaining this population in an effective and dignified manner will grow increasingly difficult—first in Japan, but globally soon after.

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