New Omni-Crawler can move in all directions
A Japanese team has developed the Omni-Crawler, a crawler-type vehicle that can move in all directions (Image: DigInfo)
When the need to move super-heavy objects arises, short, squat crawlers are usually deployed to get the job done. Unfortunately, that heavy lifting ability comes at the sacrifice of mobility (no sideways motion), so maneuvering objects into place can be a lengthy process. Recently, researchers from Japan's Osaka University (OU) rolled out an innovative battery-powered, remotely controlled prototype crawler that incorporates properties from an omni-directional wheel known as the Omni-Ball (also designed by the OU team), to travel in virtually any direction desired with minimal energy loss. They dubbed it the Omni-Crawler, and it could change the way things are moved from now on.
We've been following the quest for omni-directional robots/vehicles for some time, so the general concept is far from new. This device is unique, however, in that it utilizes two cylindrical crawlers which borrow properties from the team's unusual, two-piece ball-shaped wheels. The Omni-Balls consist of two matching hemispherical "wheels" connected to one another on either side of a short axle. The separate halves can rotate independently of one another, or in tandem as a complete sphere.
"By rotating the axle dynamically using a motor, we can effectively combine the direction of the driving force and the direction in which the structure moves as a caster. A moving object with at least three of these wheels can generate a driving force in all directions," explained OU's Kenjiro Tadukama.
"With a conventional crawler, if you position it to enter a narrow space, the crawler has to turn round repeatedly, but this crawler can move sideways as well, so it's easy to fine-tune its movements," said Tadukama. "Ordinarily, there's a lot of energy loss due to turning, but this crawler can be positioned immediately by moving to the side just a little. So we think this crawler can greatly minimize energy loss as well."
The OU researchers also showcased a number of other devices, including a "planetary exploration robot," that are based on the Omni-Ball/Crawler technology - many of them are outlined in the video below. Indeed, the potential applications for this technology seem endless, so we may see many things rolling along a lot more smoothly in the not-too-distant future.
About the Author
A native San Franciscan, Randolph attended the U.S. Naval Academy at Annapolis, Maryland before finding his way to the film business. Eventually, he landed a job at George Lucas' Industrial Light + Magic, where he worked on many top-grossing films in both the camera and computer graphics departments. A proud member of MENSA, he's passionate about technology, optimal health, photography, marine biology, writing, world travel and the occasional, well-crafted gin and tonic!
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What is the benefit of this over the mecanum wheel base?
I do not see that working real well. the cylinder shape of the track greatly reduces its footprint and thus increases the ground pressure and the side ways movement is limited to a few degrees or in intervals of 180 degrees.
It appears to me that a large number of legs with two independently powered wheels mounted so that they are free to rotate around the leg would work a lot better. By driving the wheels in opposite directions you can point them in the direction you wish to travel.
I think this would have less \'slip\' then mecanum
While 180 degree intervals would be idea the tracks could still work on their sides within a +- 45 degrees if my maths are correct granted it will be slower and cause more binding.
I believe the second part of what you are saying is called \'swerve\' or \'crab\' drive where the wheel is mounted on a controlled caster free to rotate the direction of the wheel as well as rotating the wheel itself. I saw a version that was able to rotate continuously (as in never stop rotating). That drive has the advantage of retaining full traction of a wheel but the cost is that it increases the complexity of the mechanics, electronics, controls, and programming. Be ready for a bunch of vector analysis!
On a general note I can see this being effective is search and rescue environments where awkward movements are necessary. Precision, I believe, could be ok but there is going to be a lot of slop integrated over time unless external position measurements are taken.
As Slowburn said, this design would put more pressure per square inch on the ground than a traditional track, making it unsuitable for heavy loads. Conventional tracks have a huge surface area in contact with the ground compared to tires, wheels, and most legs (which is why an Abrams tanks puts less pressure per square inch on the ground than an average car). However, this is an excellent design for search and rescue robots, as pointed out by drakesword (especially that triangle-shaped design with three tracks). It has the maneuverability of a machine with legs or swiveling wheels while keeping the ruggedness of a track.
It has been my experience that the disadvantages of a simple design with a high-friction side loading such as those tracks will experience at more than a few degrees off center out weigh the disadvantages of a more complex design that has the load going through the bearings at much more optimal direction.
I would also put a really good brake on the caster as well, unless i decided that the steering was better done with a worm drive on the caster rather than differentiated torque on the ground wheels.
The principle is GOOD, it only needs to be uprated for use under heavy objects, such as moving houses and similar.
I am sure there are opportunities to improve it and they may very well end up creating a market for themselves.
It\'s fast and it\'s responsive - goes in all directions.
I like the soft grabber device. If it were turned inside out it could shoot through tubes.
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