Macanum ability to climb ramps
 

My team and I were wondering how effective climbing ramps with mecanum wheels would be. I recall from years past they are not very good at climbing ramps, but I was wondering if you used encoders to set a certain speed if they would climb better. Thanks for the input.

Re: Macanum ability to climb ramps
 

Our team was also throwing around this idea, as it would make the robot easy to maneuver/block balls from getting into your goals and to get to balls.

this is the major deciding point on our robot; Do we want to be able to go over the ramps, or do we want more maneuverability and be forced to fit under the passageway!

Have any teams tested Macanum wheels and their ability to make it over the "Hump"?

-McGurky

Re: Macanum ability to climb ramps
 

You might high center on the hump (this could also affect a 4-wheel tank).

Re: Macanum ability to climb ramps
 

ya my team is buying some, we have pretty much given up trying to get over the ramps, and going with a real low center of gravity with mecanum wheels, we see that it might not be to important to get accross the arena except at the end

Re: Macanum ability to climb ramps
 

I can think of two mecanum drives that could do it. 1322 has been playing with one that is specifically designed to climb ramps for a couple of years now: http://www.chiefdelphi.com/media/photos/32185

2826 has a slightly different method that may be more practical: http://www.chiefdelphi.com/media/photos/34306

Re: Macanum ability to climb ramps
 

I played with some mecanum wheels a few years ago on a small scale and I was surprised with how well they climbed over objects. One of the things I did notice though was that the climbing was very Dependant on the surface on which they were climbing. Since the bumps this year are carpeted I would venture to say that a mecanum wheel-ed robot shouldn't have too many problems with climbing over the bump with the proper fame setup. (May require some suspension)

I know that I've been kicking around the idea with one of the students on my team and we think that a mecanum drive based upon the new C-Base for 2010 should be able to climb the bumps without too many problems with some creative weight placement.

Also, If I remember correctly, 357 used some custom mecanum wheels in 2006 and they were able to climb onto the ramp that year without too many problems...

Re: Macanum ability to climb ramps
 

These are both cool designs, and could be very useful this year. Unfortunately, it looks like the GDC doesn't want us to be that inventive:

Re: Macanum ability to climb ramps
 

Who said anything about these being in the frame perimeter? Remember, that's counted starting at 10" above the floor. It's not that hard to put a frame around the outside of these at that height, is it?

Re: Macanum ability to climb ramps
 

if you're not articulating the bumpers out of the bumper zone, there's nothing wrong that I can see.

In any case the first one seems valid since it's just a raised wheel.

Re: Macanum ability to climb ramps
 

Actually, it isn't. It's a full suspension. The omnis in the middle start out in a plane with the mecanums. They also happen to have a pivot point for the front of the frame, which can go up or down, sides independent. (In this picture, down; a few moments before, it would have been up.)

Re: Macanum ability to climb ramps
 

My team were throwing around ideas today. And an idea of a 2 part frame that bends in the middle to get over the humps would work really well.
It would have to use six wheels though. But getting over the humps would be easy. =]

Re: Macanum ability to climb ramps
 

My team was throwing around a similar idea-tank treads (on a smaller scale). I think this would be more effective especially for going over the ramps.

Re: Macanum ability to climb ramps
 

these are good ideas, especially the six wheel one. But how about just a standard four wheel mecanum drive train? I'm wondering if any teams tried this for 2006 or even 2007 and how they worked or if anyone saw how they worked.

Re: Macanum ability to climb ramps
 

It's not a 45 degree incline, by any means, but we got our mecanum to go up a ramp a couple years back. The first try didn't work, so we fixed up a few things (hence the clip of a student welding the frame) and then tried again.

The catch is keeping all four wheels in contact at the same time... but here's proof that a "standard" mecanum can climb at least a shallow incline. http://www.youtube.com/dtengineering...12/gyn9e0cT3-A

Jason

P.S. If you want omni directional drive ability, plus climbing... perhaps some form of crab drive is what you're looking for?

Re: Macanum ability to climb ramps
 

maybe for omni drive... Our Linkage might make a come back?

That would be awesome for me at least.. and I know some people on here liked it back when I posted it. If anyone is interested let me know I'll give out any details you need

Re: Macanum ability to climb ramps
 

Thanks for the video Jason! Pretty neat stuff. I have to note that the ramp is not carpeted. It seems pretty promising, and if used in combination with a really simple suspension, we may have a winner!

Re: Macanum ability to climb ramps
 

I want everybody to know that I am getting HECK!!!! from my team mates for posting our drive system. It was fine before this game.

Re: Macanum ability to climb ramps
 

I hope, at the same time, they are feeling very pleased with the opportunity to put your off-season R&D to good work!

Anyone who tries to copy that drive system will be weeks behind where you guys are right now... and even if they do manage to copy it, I'm sure you'll be on to version 2 before they even get a test platform built.

<rambling>

But this thread has me thinking that maybe we do want to revist mecanums this year... not with an articulated system like that one, that's just a bit beyond our build capacity this year, even if we replaced the central clutch with an FP and gearbox to drive the omni wheel... but instead... maybe if the front wheels also ran a belt... that didn't connect to the rear wheels (or else the pulley just free-wheeled on the rear axle) so that when you get high-centred on the climb the belt does the driving. It would be a combination of mecanum and tank-tread drive....

Hmm... I'll be interested to see what the students say on Monday. This game does seem well-suited to an omni drive, but the extra degrees of freedom offered in their mobility come at the cost of build time, programming time, and driver practice time.

But if a team hasn't built a mecanum drive... and wants to give it a try... you've gotta do it! I think mecanums are the most beautiful drive system to watch, and just love having seasoned engineers come into our shop and have a Grade 10 show them a wheel that they never knew existed!

</rambling>

Jason

Re: Macanum ability to climb ramps
 

FWIW, I recall a video on the Airtrax website a few years back that showed Mecanum wheels climbing stairs. The key is, as has already been pointed out, ensuring that you don't high center, and that your rollers have enough friction to make it up (where "enough" depends very much on the dimensions of your wheel base).

Re: Macanum ability to climb ramps
 

LOL All of us gave poor Joe an earful and grounded him from CD!!! J/K!! We still love him, he is our super hero around here!!!

Re: Macanum ability to climb ramps
 

In another thread someone posted a picture of the "hump" in the floor near the TOWER....looks like some type of suspension will be a big help for a Mecanum wheeled robot.

Re: Macanum ability to climb ramps
 

Just remember, you're already on Version 3 or so, and have the exact plans. We don't, therefore, we are at a significant disadvantage in terms of time to reverse engineer. Go win some awards with that drive!

Re: Macanum ability to climb ramps
 

According to my calculations, we should be able to climb ramp as long as coefficient of friction is greater than 0.4

Re: Macanum ability to climb ramps
 

This is almost exactly what we are building right now. We want to mock one up and see just how well it does...

Patrick

Re: Macanum ability to climb ramps
 

We did test our design and it jumped right up on the "bump" with no problem. ( I have video but my team won't let me post it here:confused: ) UT?

Re: Macanum ability to climb ramps
 

"Ideas are cheap,The combination of ideas and execution and excellence and the whole process is what really matters." Woodie Flowers

Re: Macanum ability to climb ramps
 

And according to AndyMark's website, The 8" Mecanum Wheels have the following coefficients of friction:

Radial Static: 0.7
Radial Dynamic: 0.6
Transverse Static: 0.7
Transverse Dynamic: 0.6

All of which are greater than 0.4, so in theory the 8" mecanum wheels from AndyMark should work. Although we have been hearing mixed results from various mecanum wheel tests, we are confident that we will be able to make it over the "humps"

Happy Prototyping! ;)

-Mcgurky

Re: Macanum ability to climb ramps
 

The reason mecanums wouldn't be able to climb the humps isn't that the wheels have low traction, it's that if you go any direction other than head-on, at least one of your wheel's rollers will free spin the robot down the ramp.

Up the ramp straight is certainly doable.

Re: Macanum ability to climb ramps
 

That sounds reasonable (as long as you don't high center), as the rollers aren't exactly powered or anything. Especially don't try to do it going up on the diagonal of your robot.

Re: Macanum ability to climb ramps
 

That's a very good point.

I remember some teams talking about playing with how tight their rollers were back in the day. This makes it harder for the rollers to free spin, which increases traction when not going straight, but also will make it slightly harder to strafe. It's something worth playing with.

Re: Macanum ability to climb ramps
 

Team 1058 took our old 2007 drive system(pictures posted here somethere) and stipped it down, to just wheels and frame, we tehn flipped it over, making moree frame clearance, and we were able to almost get over the ramp (most of the time). This was a quick prototype (we spent about 2 hours modding it (wheels had to be reverse after we flipped it, new cotrol system ect)), but with some extra elevation on the frame (maybe like 3 inches) we will be able to get ovet the hump with no issue.

Re: Macanum ability to climb ramps
 

We were able to get the 6 inch up the ramp and the 8 inch walks over it. If anybody looks closely they would see our video of the 6 inch going over the 45 degree ramp. No problem at all.

Re: Macanum ability to climb ramps
 

so basically,
everyone is saying that in order to effectively climb the ramps using mecanum wheels, you need to either have 6 wheels or have your robot be able to bend in half ?

also, i have been searching to see if there are any mecanum wheels that have tread on them and i haven't found any. is it possible to buy these or am i looking for something non-existent ? :P

Re: Macanum ability to climb ramps
 

Mecanum drives with a lot more traction then they have now could have issues with breakers tripping and whatnot. Power draw gets pretty big.

Re: Macanum ability to climb ramps
 

Our (modified) 2008 robot (with Mecanum) mostly made it up and over the ramp. I say mostly, as we had to compensate for a high CG. But I think it worked...mostly.

Re: Macanum ability to climb ramps
 

Video: http://www.youtube.com/watch?v=jQMcw4QNCLI

Re: Macanum ability to climb ramps
 

That picture there shows a frame that wouldn't flex at all. That is, unless you incorporated some sort of sliding mechanism. I can't spot anything like that in the drawing.

Re: Macanum ability to climb ramps
 

As it is now, that robot in the video would violate <R11>, but I'm assuming you're planning on adding a fixed frame perimeter as shown in the picture? That looks like a very good design to me. Though as the above poster said, you'd have to allow some sliding at those pivot points. And when it is on flat ground, all the wheels would line up, leaving the bumpers 10" off the ground.

Re: Macanum ability to climb ramps
 

That might be a question for the GDC... Couldn't it be argued that an articulating robot inside a static frame is basically an articulating frame on a static robot? (That is to say, if your bumpers are changing height with respect to the rest of the robot while you're on the ramp, aren't they articulating and thus illegal?)

Re: Macanum ability to climb ramps
 

I check the movement of a standard frame against our robot desing and ours actually moves 1/2 in less. The rule is inffect when the robots are on the flat ground and our passes that test on flat ground ( all robots bumpers move up and down going over the ramp).

Re: Macanum ability to climb ramps
 

OK Proof of concept video... Yes Mecanums can negotiate the bump...we used 8" mwcanums. See?

http://www.youtube.com/watch?v=UQQ67SB8Acc


Steve

Re: Macanum ability to climb ramps
 

Nice...:) It goes over with out effert. How does it do at high speed???

Re: Macanum ability to climb ramps
 

Haven't run it at full speed yet, but I predict a good 8 FPS at least. Our programmers hadn't finished but we wanted to end the day with progress. We'll have it running full speed tomorrow.

Steve

Re: Macanum ability to climb ramps
 

How does it do with weight? If you placed/mount plate weights or something of that nature on your frame, does it still climb efficiently? I'd like to know because we're considering something similar but don't have the wheels in hand to play with yet.

Re: Macanum ability to climb ramps
 

This configuration works best when you are at a right angle to the bump.
OK Speed. I think it is pretty decent. Perhaps not the fastest bot out there but fast enough to compete and still be controllable.

http://www.youtube.com/watch?v=pD2tsY8JKa8


Good point. everything is just strapped together right now, so we havn't weighed it down, I think we have enough spare push for a completely loaded robot. I'll post when we get to that point.

Re: Macanum ability to climb ramps
 

Team 1058 has a simple but working rptotype drive system, jsut to proove that its possible with mecanum, and that you only need a GC of about 6"...

http://www.youtube.com/watch?v=pcx7_ff-0_M

Watch at the end and we can actually dise shift on the hump, giving us the ability to move out of the way if someone tries to prrevent us from going over

Re: Macanum ability to climb ramps
 

We're not as as far along with evaluating the mechanum for front wheels. Our first line-up of wheels went over the bump OK at head-on orientation. However, coming in at an angle engaged the bump so that the front went sideways DOWN the ramp and "failed" to impress us as a possibility. The mechanums at the four corners on a running chassis looked good. I'd like to see it try an angled run at the bump. Maybe it doesn't matter how you start at the ramp since the rear wheels could easily get sideways to force a 90 degree crossing early in the attempt. I'm impressed by the side-to-side travel ON the bump. You can select your descent path to avoid entanglement with a robot in the destination zone. very cool option.

Re: Macanum ability to climb ramps
 

Impressive.