Distance of travel while using mecanum wheels
 

How do you calculate the distance the robot will travel relative to the rotations of the mecanum wheels while strafing, going forward, and a diagonal?

Re: Distance of travel while using mecanum wheels
 

If I were in a time crunch with an assembled robot in front of me I would drive a known number of rotations and then measure the distance traveled.

Re: Distance of travel while using mecanum wheels
 

I'll take the "going forward" part: Same as any normal wheel.

OK, somebody else take the others.

(Seriously, I agree with the "measure it" suggestion. Better than any calculation or guess.)

Re: Distance of travel while using mecanum wheels
 

If it were me, i would use an accelerometer and gyro, to much slip in mecanums to be able to be reliable especially when you are moving in a non-forward direction

Re: Distance of travel while using mecanum wheels
 

If you truly want reliable data here, you might want small, lightly loaded, unpowered wheels on the ground that are hooked to encoders.

Vex omniwheels work great for this, you can measure X with one and Y with the other.

Re: Distance of travel while using mecanum wheels
 

As already stated, forward and backward is easy, it just acts like any other wheel here. As for strafing, this will depend on the angle of the rollers on the wheel, most will be 45 degrees, but I've seen other angles. If the rollers are set at 45 degrees then in the best case, the robot will strafe at the same rate it moves forward or backwards. Of course there will be some scrubbing losses, so it won't be optimal, but that is true or forward and reverse as well.

Re: Distance of travel while using mecanum wheels
 

^ I can confirm this post. We did our testing in early 2010.

Re: Distance of travel while using mecanum wheels
 

Team 93 is using a small omni drag wheel with encoder that is pressed to the ground with surgical tubing to determine exact distance travelled in autonomous. The gyro is also used to ensure that the robot stays properly aligned with the scoring rack.