Macanum ability to climb ramps

[BIGWILLI2081]

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.

[McGurky]

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

[kirtar]

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

[Captain Fink]

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

[EricH]

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

[thefro526]

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...

[Abrakadabra]

Originally Posted by EricH

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

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:

<R11> The FRAME PERIMETER must be comprised of fixed, non-articulated structural elements of the ROBOT. The FRAME PERIMETER must remain a fixed, unchanging polygon throughout the MATCH.

[EricH]

Originally Posted by Abrakadabra

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:

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?

[kirtar]

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.

[EricH]

Originally Posted by kirtar

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.

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.)

[Robotbug]

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. =]

[karatekid]

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.

[RLStaple]

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

[McGurky]

Originally Posted by RLStaple

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

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

[Chris is me]

Originally Posted by McGurky

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"

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.