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#1
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Friction coefficients for Omni wheels and Mecanum wheels from AndyMark
Mark and I did some work last night that has been overdue. We performed a test of friction coefficients on our wheels from AndyMark, Inc.. We got some interesting results.
Each wheel was tested in 4 ways: Radial Static Friction Radial Dynamic Friction Transverse Static Friction Transverse Dynamic Friction Radial friction could also be considered driving friction, as it is the friction involved when the wheel is being driven forward and reverse. Or, it can be applied when the wheel is stationary and it is resisting a force from the front or back. Transverse Friction is the ability of the wheel to move sideways, or scrub. This is also the friction involved when the wheel is stationary and a force from the side is applied to it. Static friction is involved when the wheel just begins to move from a stationary position. Dynamic friction is involved when the wheel is already moving. 6 wheels were involved in the testing: 8" and 6" Plastic Omni Wheels 8" and 6" Aluminum Omni Wheels (not on website yet, but VERY soon) 8" Coolie Dualie Wheel (not on website yet, but VERY soon) 8" Mecanum Wheel Here are results: 8" Plastic Omni Wheel
<edit... These tests were made on FRC-type carpet, with 30 lbs. of downforce on each wheel. The omni wheels were tested individually, while the Mecanums were tested in a right and left pair, with 60 lbs. of downforce. (thanks for the question, Andrew Blair) ... end edit> Andy Baker Last edited by Andy Baker : 05-12-2006 at 20:27. |
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#2
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Re: Friction coefficients for Omni wheels and Mecanum wheels from AndyMark
Correct me if i'm wrong, but doesn't the mecanum wheel have a theoretical value of .707? (cos45)... Which means you're doing fairly well.
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#3
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Re: Friction coefficients for Omni wheels and Mecanum wheels from AndyMark
Quote:
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#4
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Re: Friction coefficients for Omni wheels and Mecanum wheels from AndyMark
I don't think you can have a theoretical coefficient of friction. My engineering professor said that it has to be measured.
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#5
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Re: Friction coefficients for Omni wheels and Mecanum wheels from AndyMark
Andy, what surface were these tested on? Game carpet probably?
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#6
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Re: Friction coefficients for Omni wheels and Mecanum wheels from AndyMark
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Andy |
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#7
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Re: Friction coefficients for Omni wheels and Mecanum wheels from AndyMark
Is there a chance of future testing using other relatively common FIRST field materials like HDPE?
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#8
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Re: Friction coefficients for Omni wheels and Mecanum wheels from AndyMark
Thanks Andy.. great info.
As we're prototyping with the 4" traction wheels from AM, and we're looking for more traction, does anyone have any thoughts for materials with a higher cof than the rough top? Any thoughts would be appreciated. |
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#9
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Re: Friction coefficients for Omni wheels and Mecanum wheels from AndyMark
the brecoflex stuff.. Supergrip green, is it? 1.5-1.7 vs. 1.2-1.3, I think.
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#10
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Re: Friction coefficients for Omni wheels and Mecanum wheels from AndyMark
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However, like you said, I thought they had something more grippy. |
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#11
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Re: Friction coefficients for Omni wheels and Mecanum wheels from AndyMark
Ignore that. They sent out a message to all teams at the start of the 2006 season, and they reported the findings of their tests of several of their backing material on the carpet, diamond plate, and ramp.. Its in the white paper's section somewhere. That message aside, I don't think I have ever seen anything grip better than the green brecoflex treads.
edit: http://www.chiefdelphi.com/media/papers/1772 |
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#12
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Re: Friction coefficients for Omni wheels and Mecanum wheels from AndyMark
Hey Joel...
Thanks for the info... I had searched the white papers and somehow missed this. I'll give them a call. On a side note, is your footer up-to-date? If so, I'll see you in Hartford and on LI. Regards, |
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