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Linux-based bipedal robot endures kicks and dodgeball attacks

Mar 17, 2015 — by Eric Brown — 1,678 views

OSU demonstrated its speedy, bipedal ATRIAS robot withstanding a barrage of kicks and dodgeballs. ATRIAS runs on ROS and a real-time Xenomai Linux kernel.

Researchers at Oregon State University’s Dynamic Robotics Laboratory have demonstrated their Linux-driven ATRIAS robot withstanding a considerable beating while keeping its cool. OSU recently posted videos of its unusual torture testing procedures, which include human kicks and a barrage of dodgeballs, as reported by IEEE Spectrum. Eventually, the human-sized bipedal robot is knocked from its feet, but not before it absorbs a lot of hits. The robot protects itself with strategies such as side stepping and hopping on one foot (see videos farther below).

ATRIAS endures simultaneous dodgeball attack
(click images to enlarge; source: Oregon State University)

The robot will be showcased at the DARPA (Defense Advanced Research Projects Agency) Robotics Challenge Finals, to be held June 5-6 in Pomona, Calif. ATRIAS is not yet ready to participate in the challenge itself, but its cutting edge leg design will be demonstrated in a special presentation.

The robot’s resilience should pay off in faster, more agile, next-generation disaster response robots. One of the favorites of the current generation is the newly autonomous Atlas Unplugged robot from Google’s Boston Dynamics, which is being used by seven of the DARPA Robotics Challenge entries.

One advantage ATRIAS has over Atlas and similar bipedal robotics designs is its potential for greater speed. Consolidate Times quotes project leader Jonathan Hurst, an assistant professor at OSU as saying: “When this robot gets up to speed for walking, not even running yet, it will be the fastest bipedal robot in the world.”

ATRIAS takes one for the team (left) and avoids and obstacle.
(click images to enlarge; source: Oregon State University)

The ATRIAS acronym — “Assume The Robot Is A Sphere” — refers to the dynamics of its “spring-mass” engineering model, which borrows attributes from running birds like the chicken or ostrich. With the spring-mass model, the robot can walk and run with much greater economy and battery efficiency than most bipedal bots. It’s not only potentially very fast, but quite stable, an attribute that is enhanced as it steps in place in a motion called dynamic standing.

The four-bar leg mechanism is made of a lightweight carbon-fiber material, and is designed to soften the blow of each footfall on the central unit that houses its Linux computer and other components. The lightweight shins and thighs reduce shock loads, and the legs’ “series-elastic” fiberglass springs provide further suspension, and act as mechanical energy storage, according to the OSU researchers. ATRIAS is usually operated with a boom tether, although it can navigate on its own, and will eventually be fully autonomous.

ATRIAS requires an entirely different type of mathematics than is typically used to control robotic walking, say the researchers. Hurst and other OSU researchers worked with Hartmut Geyer’s laboratory at Carnegie Mellon University to develop unique controllers for the robot that enable it to maneuver over obstacles and run at speed. A third ATRIAS model is being used at Jessy Grizzle’s lab at the University of Michigan in addition to the OSU and Carnegie Mellon prototypes. Grizzle’s research focuses on dynamic 3D locomotion that will eventually let the robot work without its tether.

As the videos show, the robot’s novel controller scheme is able to respond quickly to unexpected events and hazards, which are likely to appear in a disaster situation. As a 2013 paper [PDF] by Hurst, as well as OSU’s Andrew Peekema and Daniel Renjewski shows, the fast response is partially driven by a control computer that runs a hardened, real-time Xenomai Linux kernel. The control unit also uses the open source OROCOS real-time control environment and toolchain, as well as the open source ROS (Robot Operating System) robotics software framework.

ATRIAS controller architecture with wirelessly connected, Xubuntu-based GUI computer (top), and onboard Xenomai-driven control unit (bottom)
(click image to enlarge)

Xenomai is commonly used in advanced robotics designs, such as the Italian Institute of Technology’s Hydraulic Quadruped (Hyq) robot, and EPFL’s Biorobotics Laboratory similarly quadruped Cheetah-cub Robot. Xenomai enables the system to respond to events while adhering to strict temporal deadlines, which, if not met, may lead to system failure.

The robot code also spans a separate GUI computer that communicates with the control computer using a wireless connection. The GUI computer runs the Ubuntu based Xubuntu Linux along with ROS.

OSU has yet to publicly document the computer or other mechanical and electronic components of the ATRIAS prototype. The open source controller design, however, can run on any Linux computer, preferably in mini-PC form. The controller system depends on EtherCAT for internal communications.

ATRIAS attacked by dodgeballs

ATRIAS gets his kicks

Further information

The ATRIAS robot prototype will be demonstrated at the DARPA Robotics Challenge Finals, which will be held June 5-6, 2015 at Fairplex in Pomona, California. More information may be found on the OSU Dyamic Robotics Lab ATRIAS website.

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