I was a robotics software engineer on a project that built a mecanum wheeled robot. The big problem is that the rollers are small relative to the wheel. You know how bicycles handle rough terrain better than skateboards? The actual rollers on a mecanum wheel are pretty small compared to the diameter of the wheel they are mounted on. Our robot could handily carry a person on a flat floor (the engineers mounted a chair on a prototype and we got to sit on it and drive it with an Xbox controller - an actually extremely fun activity that could make a nice carnival ride). But if the robot encountered a pencil on the ground, the rollers couldn’t roll properly and things would get messed up.
I think I’ve seen suggestions of using the wheels for mars rovers, but a mecanum wheel that works in sand would need the rollers to be very large, so the actual wheel would be huge. That would suck up all your weight budget for your robot. Ackermann steering is lighter.
All that said, when you have a controlled environment with a flat floor, mecanum wheels are pretty rad!
Omni/poly wheels have similar drawbacks but perhaps less so. Arranged holonomically they provide about the same abilities. Possibly cheaper to purchase and maintain.
Do they have to be small? Geometrically you'd think that they could be a reasonable fraction of the wheel diameter without clashing. The roller width is the limiting dimension because that defines how close to the wheel axle the edge of the roller can get - would thin, large diameter rollers work?
Yeah that’s true, instead of small diameter wide rollers, you could have large diameter narrow rollers, like for example bicycle wheels or scooter wheels. Actually you could even use tracks for the rollers, which might be an interesting innovation. That would increase friction and reduce battery life, but there may be some advantages. Of course it would be very complex mechanically!
But something made with scooter wheels could be used to navigate around a city for example. That might be interesting.
You can buy these on AliExpress for lego so you can make cheap flexible lego robotics project using them. For robotics prototypes, for me, nothing beats lego:
I got that truck when it was on sale some time ago, only for the wheels. But as others have pointed out, they are not very practical because they gobble up dirt and stuff like nothing else
Mecanum wheels are great when used in the appropriate setting. Which is: indoors, where there are only very small disturbances in the floor. And even then you might want a very little bit of suspension like on the robot on the left here: https://www.flickr.com/photos/techunited/27997314227/in/albu... that I used in RoboCup@Home This robot drove so smooth it could sneak up on you (in a relatively noisy hall, fair enough)
The math to control them well might be an interesting task for a student perhaps.
AND no dust, grime, etc. These tiny wheels get dirty and clog up pretty fast in human environments and then stop to work and need a good cleaning. Nice for demos but unsuitable for even normal research lab work. I hate them.
They suck for carpet as well, which you'll find in a home environtment. The diagonal motion chews carpet with short strands up over time. If you have long strands in a carpet, you'll lock up in those pretty fast I suppose, though I never tried it.
I tested the robots in the picture I linked, once in a 'help a human' emergency scenario test: the 'host' dropped on the floor. With her long hair spread around. We E-stopped the robot because it drove close to that hair and we didn't want to risk it getting in the rollers. That would have been very ugly.
Uh, I've never worked with them, but the linked Wikipedia article states that the US Navy did early development in order to create equipment to move things aboard aircraft carriers. I've never been to one of those, either, but it sure seems like an environment that might be a bit more challenging than a robotics lab.
Plus there's an image of a container-slinging machine being used at airports.
So I guess my point is that I'm sorry you were burned by them, but they do seem to be usable in the real world, too.
Also: had forgotten the inventor was kinda Swedish, yay! :)
Edit: I made it sound like the container-machine used Mecanum wheels on the tarmac which of course is not the case.
Parent comment I believe refers to using the wheels as a means of horizontal displacement, not to move items on top of them. They pick up dirt from the floor that is hard to remove.
> The math to control them well might be an interesting task for a student perhaps.
There are various papers discussing this topic with four or also three mecanum wheels from the early 2000s (often related to robot soccer). Here's one picked at random: DOI: 10.1109/ICSMC.2006.385024
I was a robotics software engineer on a project that built a mecanum wheeled robot. The big problem is that the rollers are small relative to the wheel. You know how bicycles handle rough terrain better than skateboards? The actual rollers on a mecanum wheel are pretty small compared to the diameter of the wheel they are mounted on. Our robot could handily carry a person on a flat floor (the engineers mounted a chair on a prototype and we got to sit on it and drive it with an Xbox controller - an actually extremely fun activity that could make a nice carnival ride). But if the robot encountered a pencil on the ground, the rollers couldn’t roll properly and things would get messed up.
I think I’ve seen suggestions of using the wheels for mars rovers, but a mecanum wheel that works in sand would need the rollers to be very large, so the actual wheel would be huge. That would suck up all your weight budget for your robot. Ackermann steering is lighter.
All that said, when you have a controlled environment with a flat floor, mecanum wheels are pretty rad!
Omni/poly wheels have similar drawbacks but perhaps less so. Arranged holonomically they provide about the same abilities. Possibly cheaper to purchase and maintain.
Do they have to be small? Geometrically you'd think that they could be a reasonable fraction of the wheel diameter without clashing. The roller width is the limiting dimension because that defines how close to the wheel axle the edge of the roller can get - would thin, large diameter rollers work?
Yeah that’s true, instead of small diameter wide rollers, you could have large diameter narrow rollers, like for example bicycle wheels or scooter wheels. Actually you could even use tracks for the rollers, which might be an interesting innovation. That would increase friction and reduce battery life, but there may be some advantages. Of course it would be very complex mechanically!
But something made with scooter wheels could be used to navigate around a city for example. That might be interesting.
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You can buy these on AliExpress for lego so you can make cheap flexible lego robotics project using them. For robotics prototypes, for me, nothing beats lego:
https://www.aliexpress.com/item/1005006145925410.html
Lego someday should make an official mecanum wheel so that people can use it in competitions.
As someone with both a) an engineering-interested kid and b) a mild AliExpress addiction, that is some dangerous stuff. But thanks, hadn't seen those!
Sometimes opening a random link in AliExpress is as dangerous as TV Tropes or Wikipedia. Ooops, sorry to mention TV Tropes.
there are also bigger ones, like this: https://aliexpress.com/item/1005006212335463.html
I got that truck when it was on sale some time ago, only for the wheels. But as others have pointed out, they are not very practical because they gobble up dirt and stuff like nothing else
Mecanum wheels are great when used in the appropriate setting. Which is: indoors, where there are only very small disturbances in the floor. And even then you might want a very little bit of suspension like on the robot on the left here: https://www.flickr.com/photos/techunited/27997314227/in/albu... that I used in RoboCup@Home This robot drove so smooth it could sneak up on you (in a relatively noisy hall, fair enough)
The math to control them well might be an interesting task for a student perhaps.
AND no dust, grime, etc. These tiny wheels get dirty and clog up pretty fast in human environments and then stop to work and need a good cleaning. Nice for demos but unsuitable for even normal research lab work. I hate them.
They suck for carpet as well, which you'll find in a home environtment. The diagonal motion chews carpet with short strands up over time. If you have long strands in a carpet, you'll lock up in those pretty fast I suppose, though I never tried it.
I tested the robots in the picture I linked, once in a 'help a human' emergency scenario test: the 'host' dropped on the floor. With her long hair spread around. We E-stopped the robot because it drove close to that hair and we didn't want to risk it getting in the rollers. That would have been very ugly.
There are mecanum wheels even for pretty big forklifts used in not very clean environments …
Bigger mecanum wheels. What matters is the size of the rollers wrt the size of the obstacles they face.
The OP made it sound as if all mecanum wheels had this issue.
A forklift also is meant to weigh quite a lot. The weight penalty is unimportant here.
Uh, I've never worked with them, but the linked Wikipedia article states that the US Navy did early development in order to create equipment to move things aboard aircraft carriers. I've never been to one of those, either, but it sure seems like an environment that might be a bit more challenging than a robotics lab.
Plus there's an image of a container-slinging machine being used at airports.
So I guess my point is that I'm sorry you were burned by them, but they do seem to be usable in the real world, too.
Also: had forgotten the inventor was kinda Swedish, yay! :)
Edit: I made it sound like the container-machine used Mecanum wheels on the tarmac which of course is not the case.
Parent comment I believe refers to using the wheels as a means of horizontal displacement, not to move items on top of them. They pick up dirt from the floor that is hard to remove.
> The math to control them well might be an interesting task for a student perhaps.
There are various papers discussing this topic with four or also three mecanum wheels from the early 2000s (often related to robot soccer). Here's one picked at random: DOI: 10.1109/ICSMC.2006.385024
The two uses of mecanum wheels are: 1. rolling on clean flat surfaces and 2. nerd-sniping.
You forgot: 3. vibration testing drive electronics and payloads.
But yeah, #2 is the primary benefit.
Been into mecanum wheels since involvement in FTC (First Tech Challenge). If you want to know how they work, this is a great resource: https://youtu.be/AlsCUzCCc-k?si=0Cqa9rFZ-F-BKRs_
Our FRC robot used mecanum wheels. It even got us to the finals in Atlanta! Team 1848!
Reminds me of the HoloTile omnidirectional treadmill floor developed by Lanny Smoot at Disney Imagineering.
[1]: https://thewaltdisneycompany.com/lanny-smoot-to-be-the-first...
For visualization: https://www.youtube.com/watch?v=noqBUEgyQ8A
Another good video about Mecanum Wheels, by Jeremy Fielding https://www.youtube.com/watch?v=AlsCUzCCc-k
People should really stop reinventing the wheel!