[LLogan]

Originally Posted by EricH

When running front-back, all 4 wheels are contributing "full power" in one direction. When running side-side, all 4 are contributing "full power" in another direction, but two of them have to work against the other two to do it. This will amplify any effects of friction and other inefficiencies that were masked by running all together.

The problem with theory is that it often leaves out reality. This is why engineers use safety factors and try to account for reality wherever they can. Theoretically, there is no friction and no inefficiency, and inefficiency (where it does exist) is uniform any way you look at it. In reality? Not only is there friction and inefficiency, but it's hard to give them a nice, easy number.

I think there has been a misunderstanding. I have never said that the front/back and strafing motions were equal realistically. I actually said the opposite, that the strafing motion is much less efficient than the forwards/backwards motion.

In the backwards/forwards motion, the wheels are still acting against each other. Simple vector analysis tells us that perpendicular components of each force vector cancel each other out. Vector analysis also tells us that the same exact thing happens in the strafing motion, however, this time, the backwards/forwards vectors are the ones that cancel each other out. The two motions have the exact same oppositions, just in different directions.

The only thing that I have been trying to prove is that each component of the force vectors on the wheels are theoretically exactly equal in magnitude. I have only been trying to prove that beliefs like this:

no, if the rollers are at 45 degrees, then the strafe speed is half of what the forward reverse speed is, because going forward, the wheels act like normal wheels, however when they are strafing, they are 2 vectors at 45 degree angles, so only half of the magnitude of the vector is in the direction of the strafe.

are not entirely correct.

Believe me, I understand the fine line between reality theory/inefficiencies. However, I'm just trying to say that the inefficiencies aren't caused by things you described. The only factor at work is the friction of the rollers. If you tighten each roller so that it no longer rolls, you will essentially have four "normal" traction, but you will no longer be able to strafe. This is because the omnidirectionality of mecanum wheels is dependent on the rollers "slipping". However, because there will never be a frictionless roller, the strafing motion will never be equal in force to the forward/backwards motion.