Omniwheels Gaining Popularity in Robotics

Omniwheels are an ingenious invention that allows a platform to move in any direction while facing any direction

2 min read
Omniwheels Gaining Popularity in Robotics

A recent workshop that involved some rapid development using RoboCup robots, a demonstration of KUKA's omniMove platform, and my previous posts on KUKA's youBot and the ETH Zurich's Rezero ballbot have gotten me interested in omniwheels.

Omniwheels and their variations (also called omnidirectional wheels, Swedish wheels, Mecanum wheels, or Ilon wheels)

are an ingenious invention that allows a platform to move in any direction while facing any other direction.

Historically, omniwheels date back to a 1919 patent by J. Grabowiecki, and have since been created in many different designs. Since their introduction by the Cornell RoboCup team in 2000 (see Raffaello D'Andrea's research paper), they have been widely used in some RoboCup categories, where they allow the soccer robots to move in a straight line, while rotating along the line in order to arrive with the desired orientation.

Apart from the RoboCup setting, omniwheels are also used in omnidirectional conveyor systems, for example for handling packages. As you can see from the top picture (showing the parts of the custom-made omniwheels for the Rezero project), the mechanical design of omniwheels is complex. This, along with the inevitable vibrations and comparatively high wear and tear, have limited their use to a few niche applications.

One such niche is moving very heavy or large goods such as large aircraft wings or the rotor blades of wind energy plants. The picture above shows KUKA's heavy load carrier, the HLC 60000. Built in 2007, it is used for internal logistics with payloads of up to 60 tons. The biggest KUKA omniMove vehicle ever built is 32 meters long, 4 meters wide and has a payload of 100 tons.

Other niches are forklifts for aircraft carriers made by U.S. company Airtrax or some versions of Segway's RMP platform.

Another interesting, but still more futuristic, application of omniwheels is to drive the spheres used in ballbots like Masaaki Kumagai's BallIP and the Rezero (or in cars in the movie "I, Robot," where they allow omnidirectional movement without reorientation of the drive unit).

Will omniwheels become the wheel choice for robotics, or will they remain a niche?

More photos:

Ray Oung's Distributed Flight Array wheel (DFA)

Omniwheel on the Rezero robot at the ETH Zurich in Switzerland

Thanks Raff, Robert, Ray and Mike!

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Robot with threads near a fallen branch

RoMan, the Army Research Laboratory's robotic manipulator, considers the best way to grasp and move a tree branch at the Adelphi Laboratory Center, in Maryland.

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“I should probably not be standing this close," I think to myself, as the robot slowly approaches a large tree branch on the floor in front of me. It's not the size of the branch that makes me nervous—it's that the robot is operating autonomously, and that while I know what it's supposed to do, I'm not entirely sure what it will do. If everything works the way the roboticists at the U.S. Army Research Laboratory (ARL) in Adelphi, Md., expect, the robot will identify the branch, grasp it, and drag it out of the way. These folks know what they're doing, but I've spent enough time around robots that I take a small step backwards anyway.

This article is part of our special report on AI, “The Great AI Reckoning.”

The robot, named RoMan, for Robotic Manipulator, is about the size of a large lawn mower, with a tracked base that helps it handle most kinds of terrain. At the front, it has a squat torso equipped with cameras and depth sensors, as well as a pair of arms that were harvested from a prototype disaster-response robot originally developed at NASA's Jet Propulsion Laboratory for a DARPA robotics competition. RoMan's job today is roadway clearing, a multistep task that ARL wants the robot to complete as autonomously as possible. Instead of instructing the robot to grasp specific objects in specific ways and move them to specific places, the operators tell RoMan to "go clear a path." It's then up to the robot to make all the decisions necessary to achieve that objective.

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