AndyMark Mecanum Wheel tests

[Andy Baker]

All,

We at AndyMark have started a study regarding AndyMark Mecanum-style wheels. We are testing these wheels with regard to the factors listed below. While there are some commonly-accepted rules of thumb regarding Mecanum wheels, we are conducting tests to see if they are actually true.

Here are our current tests:

1. Weight limit of new design of 8" AndyMark Mecanum wheels (http://www.andymark.biz/am-0083.html): Our initial tests show that these wheels can each handle 120 pounds each easily, thanks to our new roller axle design.

2. Pushing power of 8" Mecanum Wheels vs. 8" 2010 Kit wheels (http://www.andymark.biz/am-0420.html) (on carpet)

3. Distance traveled of a drive system with 8" Mecanum Wheels (using a 3 second auto-mode) vs. 8" 2010 Kit wheels

4. Pushing power and distance traveled of the system with 8" Mecanum Wheels while strafing sideways, using the same values of input with the automode, but with appropriate wheel direction changes to allow for sideways movement (thanks, Joe Blay)

These tests will be done with a lightweight drive base (~80 pounds), a medium weight drive base (~150 pounds), and a heavy drive base (~230 pounds). We will also vary the cleanliness of the rubber surface on the wheels to see how that effects the testing.

What other tests would you like to see? If you would like to request a reasonable test, you can either send me a PM or post your request in this thread.

In other news... we are currently in the middle of a redesign for our 6" Mecanum wheel. While we will still offer our current 6" wheels, we are working on a heavy-duty version, due to be out by mid-July.

Thank you,
Andy B.

[Dave McLaughlin]

Will the new version have a locking option?

[jblay]

Figure out pushing ability and speed when strafing. Essentially what you already plan to do just with strafing.

[Andy Baker]

Will the new version have a locking option?

No

[Andy Baker]

Figure out pushing ability and speed when strafing. Essentially what you already plan to do just with strafing.

Excellent input. I will add this to my list on the original post.

Andy

[rutzman]

We'd like to know if you can use different rollers to trade off on traction vs power efficiency, i.e., can you swap in some sticky rollers and what affects will that have?

[EricH]

What effect would a cantilevered load have on all of the above tests? (i.e., a mecanum robot with an arm extended it with a load) Anyone thinking about using an arm with mecanum wheels would probably want to know that.

Also, would the effect change if the arm was off the side for some reason?

I don't think it would be too hard to test this--a 5-10 lb known weight at a known distance from the frame, bolted on, should work easily.

[efoote868]

Maximum RPM? Some other destructive spin tests?

How long does it take to wear the treads down until they become unusable (vrs kit wheels and some carpet or sand paper?)

Could get messy.

[Jared Russell]

Top speed (100% throttle) with:

1. 8" mecanum wheels (forward/backward)
2. 8" mecanum wheels (strafing left/right)
3. 8" kit wheels

All with the same chassis weight, number of motors, and gear ratio.

Your pushing test will determine how much torque is lost (if any) due to the mecanum geometry - this test would answer the same question about speed.

[Lil' Lavery]

The same 3 second auto tests as mentioned before, but with rotation instead of linear distance.

[Chris is me]

Running all the tests with a rigid chassis, and then the same tests with a flexible chassis / passive suspension?

[theprgramerdude]

Maximum RPM? Some other destructive spin tests?

How long does it take to wear the treads down until they become unusable (vrs kit wheels and some carpet or sand paper?)

Could get messy.

I too would like too see this, as we demo the robot in the off season on various non-carpet surfaces, and were wondering how much we could put the wheels through without worrying about trashing the rubber. I personally know from other experiences that the hard starts and stops that can happen with a robot can be more than some driving components can handle.

It's always an option for us to replace the wheels with KOP rubbers for demos, but it's much more exciting to show off the sideways motion.

[wilmo]

Mr. Baker,

I would suggest a shock load test, much like the robot going over the bumps this year. This is were we incurred most of the damage to our AM Mecanums this year.

Thank you for including the roller-cleanliness variable. We ended up wiping down each roller with a lacquer remover before each match, especially at regionals with very dirty floors (KC, Purdue).

Thanks,
Adam Wilmes

[Nadav Zingerman]

I'd like to see a comparison of X-configuration vs. diamond-configuration Meccanum.

[efoote868]

I'd like to see a comparison of X-configuration vs. diamond-configuration Meccanum.

you mean able to turn versus unable to turn?

[DonRotolo]

I would suggest a shock load test
I second that.

For methodology, a drop from a fixed height with increasing weight, or a drop from an increasing height with a fixed weight. In my mind (empirically) I think your heavy bot, lifted 24 inches at one end and then dropped onto nominal playing surface would be adequate. See if it survives X drop cycles. X could be around 50-100.

Second suggestion: roller wear on macadam or smooth concrete (I am thinking parade duty here - can it go a mile?)

Don

[CraigHickman]

I'm curious as to the possibility of using your Mecanums in a situation where accurate odometery is required. For example, on a 50 pound robot, driving forward 10 feet at 1m/s, how much "slip" is encountered on a standard linoleum floor? The application wouldn't be FIRST, but a robot designed for SLAM (Simultaneous Localization And Mapping). Mecanums may not even be feasible for the part, but having some number of slip during normal operation would help.

[pfreivald]

While generally happy with the 6" AM mecanum wheels this year, we did have some problems with robustness and had to replace two wheels at Championship.

As such, I am particularly interested in any tests that demonstrate how much abuse they can (and cannot) take -- the drop test is a great idea. How about stress from FIRST-speed ramming (both head-on and from the side?)

Small deformations caused the rollers to rub and effected performance (not a ton, but some) on the 6" wheels. I'm not sure if this was/is an issue with the 8" wheels.

[mcf747]

While generally happy with the 6" AM mecanum wheels this year, we did have some problems with robustness and had to replace two wheels at Championship.

As such, I am particularly interested in any tests that demonstrate how much abuse they can (and cannot) take -- the drop test is a great idea. How about stress from FIRST-speed ramming (both head-on and from the side?)

Small deformations caused the rollers to rub and effected performance (not a ton, but some) on the 6" wheels. I'm not sure if this was/is an issue with the 8" wheels.

We has huge issues with deformation and rubbing of the 8" wheels. We were disappointed that theses weren't a bit tougher, good to hear the new design is, but I guess it is to be expected with the large amount of shock loads this year.

Matthew Forman
Team 1515

[camtunkpa]

To add to all the suggestions, the roughest thing on the field I saw this year was the "1/2" bump" on both sides of the ramps. I saw this bump even bend some aluminum AM omni wheels. So maybe some sideways testing on a 1/2" hard bump or something similar.

[PVCMike]

We has huge issues with deformation and rubbing of the 8" wheels. We were disappointed that theses weren't a bit tougher, good to hear the new design is, but I guess it is to be expected with the large amount of shock loads this year.

Matthew Forman
Team 1515[/QUOTE]

We also had serious issues with deformation of out 8" wheels and ended up going through 2 sets of 4 (which ends up getting pretty pricey.) The problem we were having is that the wheel plates were curling over (we assume from side load) and binding the rollers.

I would like to see some tests involving side load on the wheels, the sort of stress the wheel would see when being pushed from the side.

Mike Jr.
Team 1058 Mentor

[Hadi379]

Our main concern was the robustness of the side plates. We used the 8" wheels and noticed the same thing as the above post. Some of our rollers would get pinched between the two side plates and prevent the rollers from freely spinning.

[Chris Fultz]

Rigolith

(just in case)

[Stephen Kowski]

2. Pushing power of 8" Mecanum Wheels vs. 8" 2010 Kit wheels (http://www.andymark.biz/am-0420.html) (on carpet)

how about the same test while stapling some roughtop or wedgetop to the kit wheels, many teams use this, your company sells wheels with roughtop/wedgetop in mind....i think it would be a good piece of information to have

are you videotaping these tests? I think that would be good in addition to written results

[Lil' Lavery]

are you videotaping these tests? I think that would be good in addition to written results

MythcanumBusters.

[Taylor]

I'd like a study performed on the correct pronunciation of mecanum. I've heard "MECK-ken-nem" and "muh-CAN-um" from very reputable sources. Which is right?

[efoote868]

I'd like a study performed on the correct pronunciation of mecanum. I've heard "MECK-ken-nem" and "muh-CAN-um" from very reputable sources. Which is right?

jester drive. :p