pic: A mechanum wheel that shouldn't bump around at all.

[Ether]

Originally Posted by Brandon Holley

Like the segway mecanum wheel??

Hi Brandon,

Could you provide a link that shows the rest of this picture? I am curious to see the rest of the platform.


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[Alan Anderson]

Originally Posted by Ether

Could you provide a link that shows the rest of this picture? I am curious to see the rest of the platform.

That's the Segway RMP 400 Omni.

[Ether]

Originally Posted by Alan Anderson

That's the Segway RMP 400 Omni.

Thanks Alan.

Looks like the wheels in the picture Brandon linked to are mounted incorrectly.


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[exprg:melonhead]

hmmm... this wheel sure does look pretty, but does it run that way too? the side wheels (or whatever the technical term for them may be) look as if they are at a very harsh angle. now, i'm just a programmer, but isn't the ideal angle 45 degrees?

[Ether]

Originally Posted by exprg:melonhead

hmmm... this wheel sure does look pretty, but does it run that way too? the side wheels (or whatever the technical term for them may be) look as if they are at a very harsh angle. now, i'm just a programmer, but isn't the ideal angle 45 degrees?

There is no "ideal" angle.

Many mecanum wheels have rollers at 45 degrees. This makes the kinematic (and dynamic) analysis easier. The forward and inverse kinematic matrix transformations are simple, with no trig functions or square roots.

Making the angle smaller than 45 degrees (angle between roller axis and plane of the wheel) improves forward/reverse traction but reduces strafing traction, and vice versa.

So there is no one ideal angle. It depends on the application.


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[exprg:melonhead]

Originally Posted by Ether

There is no "ideal" angle.

Many mecanum wheels have rollers at 45 degrees. This makes the kinematic (and dynamic) analysis easier. The forward and inverse kinematic matrix transformations are simple, with no trig functions or square roots.

Making the angle smaller than 45 degrees (angle between roller axis and plane of the wheel) improves forward/reverse traction but reduces strafing traction, and vice versa.

So there is no one ideal angle. It depends on the application.


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so what you are saying is that in order to to drive easily both forward and back, it would be best to have a good 45 degree?

[Ether]

Originally Posted by exprg:melonhead

so what you are saying is that in order to to drive easily both forward and back, it would be best to have a good 45 degree?

No, that's not what I said (not even close). I'm not sure how you concluded that from what I wrote. Help me understand what part led you astray.


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[Hawiian Cadder]

nice, that is the idea with these too, we should be able to replace the arms, the main hurdle now is making the rollers so that they will fit perfectly with the bearings, can you turn urethane on a lathe?

[Brandon Holley]

Originally Posted by Hawiian Cadder

nice, that is the idea with these too, we should be able to replace the arms, the main hurdle now is making the rollers so that they will fit perfectly with the bearings, can you turn urethane on a lathe?

You sure can.

-Brando

[EricH]

Originally Posted by Ether

No, that's not what I said (not even close). I'm not sure how you concluded that from what I wrote. Help me understand what part led you astray.


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I can understand why he said that... But to ONLY go forwards and backwards, it's best to have a traction wheel. (literally, he said forwards and backwards only...)

What Ether said, in essence, was that many mecanum wheels used 45* rollers, but that other angles could be used--less than 45* puts the advantage to front/back and greater than 45* puts the advantage side-side in terms of traction. I assume that this is a correct summary. If it is not, then the original post needs to be modified, as that is where I got this from.

From that, it is easily (and logically) concluded that, for the optimal front/back and side/side traction, 45* is a better angle than many others. If that is not the conclusion that was intended, then better words need to be chosen.

[Ether]

Originally Posted by EricH

...

OK so you understood. Good for you.


Justin, what part of my post led you astray? Was it the part about the forward and inverse matrix transformations? I can explain in more detail if you are interested.


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[Rion Atkinson]

Originally Posted by Ether

OK so you understood. Good for you.


Justin, what part of my post led you astray? Was it the part about the forward and inverse matrix transformations? I can explain in more detail if you are interested.


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Honestly I would just tell him to read Eric's post. It made plenty of sense. (Now yes, yours made sense to. But there is no need to re-explain that which has been explained if it is now understood.)

[Ether]

Originally Posted by Formerly Famous

Now yes, yours made sense to. But there is no need to re-explain that which has been explained if it is now understood.

The kinematic matrix transformations were mentioned but not explained. You apparently know all about them but perhaps Justin does not and would be interested in learning.

Justin, if you are interested let me know and I'll start another thread.


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[Hawiian Cadder]

no, if the rollers are at 45 degrees, then the strafe speed is half of what the forward reverse speed is, because going forward, the wheels act like normal wheels, however when they are strafing, they are 2 vectors at 45 degree angles, so only half of the magnitude of the vector is in the direction of the strafe.

[AdamHeard]

Originally Posted by Ether

The kinematic matrix transformations were mentioned but not explained. You apparently know all about them but perhaps Justin does not and would be interested in learning.

Justin, if you are interested let me know and I'll start another thread.


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Can you please post your team number and location? You post a lot in a somewhat negative tone, which is easy to do when you have no fear of anyone associating you with a team.