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

[Rion Atkinson]

Originally Posted by Ryan Dognaux

That was done in Inventor 2010 by one of our students, Kyle Tress.

Interesting... I've never seen Inventor render anything that pretty... Looks like I'll have to play with 2011 some more.

[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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[LLogan]

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?

A forty five degree angle makes the vectors of the straight and perpendicular motions equal (this should be obvious if you know basic trigonometry). That is why it is chosen by many teams as the angle for their rollers. It theoretically should make your strafing and forward motions equal. However... I do not think that's the case. There is just too much inefficiency in a mecanum drive system.

Changing the angles will change the vectors of the wheels. A smaller angle (assuming the maximum angle, 90 degrees, is just a roller mounted straight lengthwise) should theoretically give more strafing motion. Vice versa for a larger angle and forward/back motion.