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Unread 09-01-2008, 14:47
Bob Steele's Avatar
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Re: pic: Omni Design Trial

I just wanted to point out a small error in the discussion regarding Force and Motion.

NET force will result in Acceleration ... constant velocity requires no force whatsoever.

When we accelerate robots we see the result of all the forces involved. The net force.

The other forces on the robot are varied and the one we should discuss here primarily is friction (which is a result of the weight of the robot and the coefficnet of friction between the wheels and the carpet). This frictional force is what accelerates the robot. This frictional force is a result of the wheels applying a force to the carpet and carpet pushing back.

The net force on the robot, when it is going forward is in that direction.
If the angled wheels on a set of mecanums are not turning it is simply indicating that the sideways forces are balanced. It does NOT indicate there are NO sideways forces. I would imagine that the pin loading on the bearings in this angled state is much different than when it is moving parallel to the wheel's orientation.

I you could measure the temperature of these wheels over the course of the match I would be very surprised if they do not get quite warm.

This loss of efficiency that we all discuss with holonomic or mecanum systems has to result in energy being spent somewhere else...

Anyway these are my suggestions on this topic. Specifically they would indicate why that holonomic drives and mecanum drives have to work in the same way. Force applied does not net acceleration. Net force does.

Good luck to everyone no matter what drive system they use!!!

Have a great season!!!

May the NET FORCE be with you!!!
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