Bipedal robot takes a walk outdoors

A human-sized, two-legged robot has been designed to walk outdoors by mimicking the spring-legged action of animals, embedded with technology that researchers believe could herald the running robots of the future.

In an outdoor field, scattered with lumps, bumps and uneven terrain, researchers at Oregon State University (OSU), successfully field-tested the locomotion abilities of a bipedal robot.

The ATRIAS robot can move, keep its balance and withstand mild blows from a bouncing rubber ball, while walking in the grass, up and down hills at a normal walking speed of a little more than three miles per hour.

“Animals with legs sort of flow in the energy used, in which retained kinetic energy is just nudged by very efficient muscles and tendons to continue the movement once it has begun,” said Jonathan Hurst, associate professor of mechanical engineering at OSU.

According to the researchers this is the closest a machine has yet come to resembling human locomotion. It had six electric motors powered by a lithium polymer battery, specifically designed to be smaller than the power packs of some other mobile robots.

With its elastic legs and the energy retention that’s similar to animal movement, the researchers hope the robot will soon run. “That’s part of what’s unique about ATRIAS, but that it’s doing so with animal-inspired fluidity of motion that is so efficient," Hurst said.

“This will ultimately allow a much wider range of robotic uses and potential than something which requires larger amounts of energy.”

While the trials were conducted, the robot was secured to a safety harness on a supporting frame that rolled along with it, but only as a safety net to prevent costly damage in case it fell, which it did a couple of times due to sensor glitches.

“It already appears that ATRIAS is three times more energy-efficient than any other human-sized bipedal robots,” said Christian Hubicki, an OSU PhD scholar working with Hurst. “And this was the first time we’ve been able to show its abilities outside, in a far more challenging environment than anything in a laboratory.

“This is part of a continuous march toward running robots that are going to be useful and practical in the real world.”

Immediate plans based on this technology could be developed for prosthetic limbs for people, but in the long run the running robots could also open applications in the military or in disaster response.

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