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Unread 21-01-2011, 10:20
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Re: Another chapter to the 6WD vs. Mecanum debate

Quote:
Originally Posted by Alan Anderson View Post
No, it's not physics. It's a myth. There is almost no loss of power at all during forward motion.

When a mecanum drivebase is traveling perpendicular to the axles of the wheels, as if it had traction wheels, the slipping of the rollers is almost nonexistent. There's a teeny bit of roller motion that happens on a compliant surface like carpet, but 30% is a huge exaggeration.

What you do give up with mecanum wheels is maximum pushing force. Because the individual force vectors are in different directions, the sum of the magnitude of the forces on the carpet is greater than the magnitude of the sum of those forces on the robot. The wheels will slip at the same wheel/carpet force as any other wheel having the same surface, but when using mecanum wheels that happens when there is less total force on the robot than when using traditional traction wheels.
Emphasis mine.

Because a mecanum drive has less total usable force at any given speed than a 6wd, and power = force * speed, does this not mean that mecanum drive has less available power than a 6wd?

If my interpretation is correct (please correct me if I'm wrong), the power loss in mecanum comes from the force vector cancellation during straight-line driving, not from frictional losses in the rollers.
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