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Unread 09-01-2008, 11:24
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Re: pic: Omni Design Trial

Quote:
Originally Posted by squirrel View Post
I was not talking about the case...
There are no "cases" involved. The wheels behave the same always.

Quote:
Originally Posted by squirrel
This would be the same as just rolling a normal wheel across the desk.
Rolling a wheel and powering a wheel are totally different. If you placed a keyed or hex shaft through the wheel and tried to turn it while pressing into the ground, you'd see the wheel would want to walk down the shaft. This is because the wheel produces a vector that isn't straight ahead, but at approximately 45*.

Quote:
Originally Posted by squirrel
...they do NOT have the same efficiency going forward and sideways/diagonal.
This is correct, and I said as much in my previous post.

Ok, let's try changing tack. Assume the mecanum wheels do put 100% of the power forward. We know the gearboxes can't output more than 100%, so there can't be any force sideways. Therefore, the robot could not strafe sideways.

However, we know that the robot can strafe sideways. Therefore our assumption is false and the wheels must be producing a sideways force all the time.

The mecanum wheels do not put 100% of the power forward. They behave just like regular omnis at 45* angles. You get about 70% power by moving forward, reverse, left, or right.
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