
Mecanum wheel - curtis
https://en.wikipedia.org/wiki/Mecanum_wheel
======
nimbius
Intralox belts are sold under all sorts of names...mecnasort and tabletronix
were a few older ones I recall when I first started as an industrial machinist
15 years ago. The problem with intralox is theyre relatively sensative to
weight and if one row or cluster of links goes down, it can very quickly take
the entire table down.

Mecanums on the other hand are incredible. If you need to service a four
thousand pound part, you can drag it around on a table of mecanums like its a
childs toy. Mecanums pods are even individually addressable, so you can get an
email or alert to exactly which one is under too much load, or failing.

~~~
pinot
You referring to intralox's ARBs?

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ed312
These are so damn cool. My old FIRST team wanted to use these but the lack of
traction was a real problem. Great for moving heavy & slow, not so great for
fast turns (even with relatively low center of gravity).

~~~
unreal6
My FIRST team did use them and loved using them. For our use case it was great

~~~
ed312
That's awesome! I think the year we considered it was "Aim High"
([https://en.wikipedia.org/wiki/Aim_High](https://en.wikipedia.org/wiki/Aim_High))
or one of the adjacent years. We used our previous year's robot as a test bed
and found regular wheels could too easily push our Mecanum wheel robot out of
the way / knock it off balance. Do you remember which competition you used the
wheels? What did you end up using for a driver control layout?

~~~
unreal6
We used it for Steamworks
([https://en.wikipedia.org/wiki/FIRST_Steamworks](https://en.wikipedia.org/wiki/FIRST_Steamworks)),
where speed was a priority for our light robot. Unfortunately, defense was
utilized to our detriment.

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mojomark
Yup, like the article notes, we use these on ships where there are often times
when you need to transport large pallets of material through a maze of
passages and you often don't have enough reserved deck space to accommodate
the turning radius of a normal pallet jack or 'walkie'. Material Handling
Equipment with Mecanum wheels are omnidirectional (no turning radius), so you
can transit heavy/bulky cargo through very tight passageways that would
otherwise be virtually inaccessible.

~~~
panarky
Here's a forklift with mecanum wheels (1 min)

[https://www.youtube.com/watch?v=ZW3OBb_b89k](https://www.youtube.com/watch?v=ZW3OBb_b89k)

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Zanta
Neat! I built a little mobile robot that uses omni-wheels[1], a related style
wheel. Build report here[2] (forgive the lousy website, I'm a mech guy just
starting to learn software)

The wheels allowed some neat driving tricks, but it also made it really
difficult to drive in a straight line. You don't get the normal tracking
behaviour that wheels give you, and differences in traction from wheel to
wheel also tend to distort your course. Adding a gyro for use in a closed-loop
angular control system really helped this a lot.

[1]
[https://en.wikipedia.org/wiki/Omni_wheel](https://en.wikipedia.org/wiki/Omni_wheel)
[2]
[http://willbeattie.ca/Projects/Twitch/Twitch.html](http://willbeattie.ca/Projects/Twitch/Twitch.html)

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mabbo
Reminds me of Intralox belts[0], which are used extensively in manufacturing
and warehousing. Intralox belts are conveyor belts made of tiny wheels pointed
90 degrees (usually) off of the direction the belt is traveling.

[0][https://www.youtube.com/watch?v=tqLYhhV7u7Y](https://www.youtube.com/watch?v=tqLYhhV7u7Y)

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crehn
Demo:
[https://www.youtube.com/watch?v=Ne09Y72zW_Y](https://www.youtube.com/watch?v=Ne09Y72zW_Y)

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cwoebker
When reading the wikipedia page I was surprised to learn that: "In 1997,
Airtrax Incorporated and several other companies each paid the US Navy $2,500
for rights to the technology, including old drawings of how the motors and
controllers worked, to build an omnidirectional forklift truck"

This was more than 20 years ago, but $2,500 seems on the low end for a usage-
license. This patent is pretty interesting after all. Does anyone have any
knowledge in this area? Is that average for these types of patents, or is the
Navy giving it away for cheap to incentivize new innovation?

~~~
saalweachter
'97 was 25 years after the original patent was filed, so the original patent
was well expired.

I would guess that what they were buying from the Navy were literally just the
implementation notes, because even if the patent covers all of the original,
key, patent-able ideas, it can still be a bitch to go from that to an actual
working implementation.

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amelius
This video explains it well:

[https://www.youtube.com/watch?v=O7FbDy-
gE70](https://www.youtube.com/watch?v=O7FbDy-gE70)

~~~
bergoid
It's a pity that they got the orientation of the rollers wrong.

The wheels should have been oriented either like this:

    
    
          ___
      [\]|   |[/]
         |   |
      [/]|___|[\]
    

or like this:

    
    
          ___
      [/]|   |[\]
         |   |
      [\]|___|[/]
    

instead, they managed to mount them like this:

    
    
          ___
      [/]|   |[/]
         |   |
      [\]|___|[\]

~~~
mikepurvis
The only correct configuration is the middle one. If you have the rollers
making an X then the vehicle is unconstrained about Z.

~~~
randyrand
Could you explain that deeper?

~~~
mjevans
I see where they're going now that it's pointed out.

The X pattern defines a single point of control where the lines cross, while
the 'diamond' pattern creates (roughly) four outer lines of contact and thus
for a complex terrain beneath allows for better control in the location on top
of that uneven field.

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netcraft
Theyve been made for lego robots as well:
[http://thekidshouldseethis.com/post/lego-mindstorm-
mecanum-w...](http://thekidshouldseethis.com/post/lego-mindstorm-mecanum-
wheel-vehicles-by-yoshihito-isogawa)

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mikro2nd
If the original patent was November 1972, then surely it had long-since
expired by 1997, which then begs the question of why it was necessary that:
"In 1997, Airtrax Incorporated and several other companies each paid the US
Navy $2,500 for rights to the technology"

Is there something about US patents not mentioned in
[https://en.wikipedia.org/wiki/Term_of_patent_in_the_United_S...](https://en.wikipedia.org/wiki/Term_of_patent_in_the_United_States)
?

~~~
cromulent
It seems there is some complexity and other patents involved.

From their SB2 form:

A form of our Omni-Directional technology was originally patented in 1973 and
was sold to the US Navy. We secured a transfer of this technology from the
Navy in 1996 under the terms of a CRADA agreement (Cooperative Research and
Development Agreement) and we have worked since that time to commercialize
Omni-Directional products. We received 3 patents regarding the "redesign" of
the wheel. In addition, we have a license agreements for the algorithms used
to control vehicular movement, and a patent for this technology has been
applied for. (...) The patent for the Omni-Directional wheel expired in 1990.

[https://www.sec.gov/Archives/edgar/data/1081372/000101376207...](https://www.sec.gov/Archives/edgar/data/1081372/000101376207000731/formsb2.htm)

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Damogran6
Plenty of options here if you're interested:
[https://www.thingiverse.com/search?q=mecanum&sa=&dwh=585aec7...](https://www.thingiverse.com/search?q=mecanum&sa=&dwh=585aec74c689e1f)

~~~
fermienrico
Shows no results found.

~~~
Damogran6
go to [https://thingiverse.com](https://thingiverse.com), search for mecanum.
Done!

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cecilpl2
Airbus uses them to move A380 parts around their factory:
[https://www.youtube.com/watch?v=RZ_8xhCi72w](https://www.youtube.com/watch?v=RZ_8xhCi72w)

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hatsunearu
The alternative is using Omni Wheels mounted at 45 degrees, which lets you do
translations without rotations.

[https://en.wikipedia.org/wiki/Omni_wheel](https://en.wikipedia.org/wiki/Omni_wheel)

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anonu
Liddiard wheels are a bit of an iteration on this concept:
[https://www.youtube.com/watch?v=jas_y1cUndI](https://www.youtube.com/watch?v=jas_y1cUndI)

~~~
tcfunk
Is it just me, or do the physics of the tire not make sense here? I'm clearly
missing something, given that they have a working demo.

But it seems to me that the surface area of the tire is getting stretched and
squashed as it spins horizontally.

~~~
Hupriene
Yep you are correct. It seems like the tires would have to consist entirely of
a fairly elastic material, preventing the use of banded or radial designs.

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gameswithgo
the mythbusters had a forklift or something with these wheels I believe

~~~
eco
Yeah, they had an ATX-3000 Sidewinder.

[http://www.vetexinc.com/vehicles/sidewinder.html](http://www.vetexinc.com/vehicles/sidewinder.html)

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mrfusion
Has anyone looked into these for an Omni directional treadmill?

~~~
dvh
Smarter every day had video recently about it used in VR company

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jlebrech
how well do they roll on tarmac?

Imagine an electric car that can park and drive in tight spaces.

~~~
masklinn
Neither surface nor weight seem to be issues: they're used for multisurface
forklifts, they do fine on grass or dirt or sand, they're used for heavy
lifters. They're expensive and heavy though.

But I'd be more worried about operating speed, mecanums have maybe 60~70% of
the traction of a regular threaded wheel, and probably behave much more poorly
at high speed.

On a regular car, you're probably better off with auto-parking (the tech is
getting pretty damn reliable, it's just a question of having it trickle down
from the luxury segments) or even just parking assist.

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bitwize
I think my nephew's toy robot puppy moves around on these.

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majewsky
That's one the few cases where it made sense to _[puts sunglasses on]_
reinvent the wheel.

