Teams With Mecanum Wheels

[Foss@Team176]

In the travels that my team has had i've personally have only seen one team with mecanum wheels and that is team 190. I also so the post that 357 put on CD about there "Jester Drive" and i was wondering what other teams out there have this built on their robot and how can i get ahold of them.

Goodluck in the offseason everyone, although the season never really ends does it? It's always FIRST season.



-Foss

[Veselin Kolev]

Oh man.. I just looked at 357's drive... thats gotta be the best thing since sliced bread. I know my team will definatly look into that next year.. cool.

As for how to get them, I really dont know. It seems like the kind of thing you custom make, or if you have to buy, it will be expensive. Of course custom making something like that is a nightmare without a sheetmetal shop (not necesarily, remember that I am uncreative), and I don't have a sheetmetal shop.

But I would say spending the time to CNC something like those wheels would be really cool. Sorry, Im personally a fan of anything that can move like swerve drive, be it swerve, omni, or this thingamabob.

I must say, I would have been clueless about this for a while if you hadn't posted. Thanks man, this is something I shall think about for next year.

[Tom Bottiglieri]

Originally Posted by Veselin Kolev

As for how to get them, I really dont know. It seems like the kind of thing you custom make, or if you have to buy, it will be expensive. Of course custom making something like that is a nightmare without a sheetmetal shop (not necesarily, remember that I am uncreative), and I don't have a sheetmetal shop.

I smell a new AndyMark product!

[Joe Ross]

190, 211, and 357 are the teams that I know that competed with their mecanum wheels. Several other teams (mine included) played around with them but did not compete with them.

For another interesting twist on omniwheels, look at 116.

[Ken Stafford]

[quote=Joe Ross]190, 211, and 357 are the teams that I know that competed with their mecanum wheels. Several other teams (mine included) played around with them but did not compete with them.

Just a quick comment here. Mecanum wheels can lead you to field-oriented controls. We (190) used this--357 did not, don't know about 211. Our veteran drivers were initially very reluctant to try field-orientation, once they tried it, they all loved it and never used the over-ride switch to return to robot-orientation. Basically mecanum wheels allow you to ignore the conventional front and back orientation of your 'bot (since the robot can move equally well in any orientation). Once you've accepted this there is really no reason to have your driver controls move the robot "forward" or "backward". On our controls, forward on the single joy stick always meant "down field/away from driver" regardless of the orientation of the robot, pushing the stick to the left aways moved the robot to the driver's left, etc. The orientation (yaw angle) of the robot was controlled initially by another joystick where right movement meant "spin CW", left meant "spin CCW". (We have since included this function into twisting the single stick.) The cool thing about field-oriented controls is that say you want to travel directly from a "loader" to an "offload station" but need to have the robot at different orientations. With our controls you simply push the stick in the straight line direction you need and while transiting (via a straight line), you simply twist the stick CW or CCW until the orientation is correct. While twisting, the robot track remains a straight line. It is very cool to drive! Certainly makes for a unbeatable defensive robot. It is not particularly difficult to program but you do need 4 accurate wheel encoders and a stable yaw sensor.

GOOD LUCK!

[Joe Lambie]

Sounds like a neat drive. I too would have been reluctant at first to the field orientation, but could be very useful once you are accustamed to it. Our team hopes to use Mecanum Wheels next year on our robot, perhaps we will have to look into field orientation driving. We look forward to the white paper on manufacture as well!

[Veselin Kolev]

I think it is the difficulty of fabrication that keeps teams from using mecanum wheels. Omni wheels are bad enough to make on a mill and lathe.

However... take a look at this. I think a shop with a nice mill, lathe, and tig welder can pop out four of these in 3 days. Or at least mine can

A short description of fabrication: Have a central hub with bearings that two aluminum plates bolt onto. Have slots milled into the outer parts of the plates. Slide 1/4" aluminum shaft, so it goes at 45 degrees (the milled slots do this automatically) and weld one side. Cut off extra with hack saw, repeat. At the end, mill the whole thing flat. Unbolt the side you didnt weld on, slip on the rollers, bolt back together, and poof! You have a mecanum wheel with very little effort.

[spears312]

I've seen these wheels before and thought of suggesting them for our bot, but I wasn't sure exactly how much torque or traction you could get out of them. If anyone knows these specs could you post them?

Also, after seeing those It's given me an idea for a summer project (just can't take a break from robotics ). Any one know where you can buy some on a smaller scale?

[Greg Perkins]

Originally Posted by Veselin Kolev

I think it is the difficulty of fabrication that keeps teams from using mecanum wheels. Omni wheels are bad enough to make on a mill and lathe.

However... take a look at this. I think a shop with a nice mill, lathe, and tig welder can pop out four of these in 3 days. Or at least mine can

A short description of fabrication: Have a central hub with bearings that two aluminum plates bolt onto. Have slots milled into the outer parts of the plates. Slide 1/4" aluminum shaft, so it goes at 45 degrees (the milled slots do this automatically) and weld one side. Cut off extra with hack saw, repeat. At the end, mill the whole thing flat. Unbolt the side you didnt weld on, slip on the rollers, bolt back together, and poof! You have a mecanum wheel with very little effort.

Wow sorry for giving life to an old thread, but i saw your cad drawing for your mecanums veselin and was curious...without tons of machine experience are you sure your capable of milling 45degree holes? I've taken 3 yeras worth of machining and its not as easy as it looks. IDK, i dont know your abilities but seems like it would be easier to do it all like the ones which have been mentioned (IE 190's were amazing, they had the rollers supported in 2 spots unlike the conventional ones that only have the center bracket between both rollers) and 190's the only major machining would be to make round stock flat on 8 sides...seems a lot simpler to me

[Madison]

Originally Posted by Greg Perkins

without tons of machine experience are you sure your capable of milling 45degree holes?

His design doesn't called for holes to be milled at 45*. It calls for slots to be milled in a single plane that will allow an axle to be positioned at 45* with respect to that plane. Then, he welds that axle in place and cuts it flush with the plate. Put rollers over the axles and then do the same for the other side -- weld and cut flush. No multi-axis milling is required.

The downside to the design is simply that it won't ever come apart again, so you can't replace rollers should you need to.

[Veselin Kolev]

Originally Posted by M. Krass

His design doesn't called for holes to be milled at 45*. It calls for slots to be milled in a single plane that will allow an axle to be positioned at 45* with respect to that plane. Then, he welds that axle in place and cuts it flush with the plate. Put rollers over the axles and then do the same for the other side -- weld and cut flush. No multi-axis milling is required.

The downside to the design is simply that it won't ever come apart again, so you can't replace rollers should you need to.

M.Krass, you are almost 100% correct. The slots are in the plane, so the axles just slide in and rest on the plates. However, it is only welded on one of the sides. The weld just keeps the axle from sliding back and forth, since it can't go anywhere; it is tangent to the slots in the plates. Thus, you only need one side to be welded, while the other side can still come off. This allows you to replace the rollers when they wear out.

As for the machining question, it is actually quite easy to cut those plates, even with the 45 degree cut. Since there are 12 cuts equally spaced, all you have to do is tilt your mill head over and position it to cut one of the holes (this part is tricky and anoying) and then you just use a rotary indexer or rotary table to turn the plate 30 degrees at a time. Or if youre really cheap, if you notice, there are 12 bolt holes in the center of the wheel, you can use those holes to mount the plate to the mill. Ever time you want to move over 30 degress, unbolt from the table, rotate over one hole, bolt down again. This is actually how I cut the slots in the plates. I'm too lazy to make a CNC program that will do it all at once, I just unscrew, rotate, and cut the next slot, with about 12 seconds worth of G-code. And I cut four plates at a time, so it really wasnt that much effort.

[ahecht]

Keep in mind that with cylindrical rollers, your robot will not drive smoothly. Basically, if you view your wheel edge on (so that the axle would appear to be a disc), you want the rollers to make a single circle.

I would encourage all teams to try making mechanum wheels, but keep in mind that the rollers, not the hubs, are the hard part.

[Rich Kressly]

Originally Posted by Veselin Kolev

Oh man.. I just looked at 357's drive... thats gotta be the best thing since sliced bread. I know my team will definatly look into that next year.. cool.

As for how to get them, I really dont know. It seems like the kind of thing you custom make, or if you have to buy, it will be expensive. Of course custom making something like that is a nightmare without a sheetmetal shop (not necesarily, remember that I am uncreative), and I don't have a sheetmetal shop.

But I would say spending the time to CNC something like those wheels would be really cool. Sorry, Im personally a fan of anything that can move like swerve drive, be it swerve, omni, or this thingamabob.

I must say, I would have been clueless about this for a while if you hadn't posted. Thanks man, this is something I shall think about for next year.

357 has a whole display and process laid out that will show that ANY team can make their own Mecanum Wheels. Please contact Joe Troy or Ken Delaney through CD and they'd be glad to help you, I know they would!

[Joe Troy]

We would be happy to share our experiences with the Jester Drive (Mecanum wheel) including design details and the fabrication process.

We have a pamphlet that explains how the Mecanum wheel works and a paper that outlines the process of molding rollers for the wheel.

Our Design Engineer, Jules Scogna, is working on a "White Paper" that will be made available soon.

Jester Drive proved to be very robust and simple to maintain. We competed at Pittsburgh, Philadelphia and the Championships without having to repair any portion of the dirvetrain. The Mecanum wheel system provides all the maneuverability (and more) of any "crab drive", "swerve steer" or other omni-directional drive system with fewer possible points of failure.

If that's not enough..it is also cool to drive!

If you are interested in the specifics of our implementation of the Mecanum wheel please send me an e-mail or a PM.