Need help with Mecanum wheels!!

[Team4169]

Hey robotics people, My team (4169 out of Sudbury, MA) is trying to decide whether or not Mecanum wheels will work with what design we have. So far, we've got a WIDE chassis configuration (AM14U2 from the KOP), and from what I've read the wheels may work best with the square configuration. Is this true? Our team was going to purchase the upgrade kit from Andy-Mark http://www.andymark.com/product-p/am-14u2-mk6.htm but it's been sold out. The individual parts are all in stock though, except for the wheels themselves. We are trying to find some 6" heavy duty ones, but will other sizes and types work with this upgrade kit? For anyone with experience with Mecanum wheels: Our design has fairly uneven weight distribution, particularly when carrying the totes. Will the affect the movement (strafing) at all, and is there a way to get around this, by having the drive team manually adjust the motor speed?
Also, what physical controls do people usually use to drive them?


Does anyone know if these wheels (http://www.vexrobotics.com/mecanum-wheels.html) can work with this chassis and upgrade kit (http://www.andymark.com/product-p/am-14u2-mk6.htm)? I've heard that they're much more reliable this year with the steel part and am interested in using them.


EDIT: They just sold out of gearboxes!! http://www.andymark.com/product-p/am-2679.htm Can we still use the Mecanum wheels with four of the gearboxes that come with the AM14U2 chassis? And does anyone know if there is another place to find the gearboxes?

Thank you so much guys, and good luck at the competition!!

[Alan Anderson]

Unless your program is explicitly designed to work with wheels at specific locations, then there's no problem having mecanum wheels in a non-square configuration. It's possible that a wide drivebase will turn a little more quickly than a narrow one, but that's about the only effect you should notice.

[Team4169]

Ok sounds good, thanks!

[Ben Wolsieffer]

Uneven weight distribution will cause your robot to strafe in an arc instead of a straight line. If the weight distribution isn't too far off, this can be counteracted by using a gyro and PID loop.

[Ben Wolsieffer]

As for driver controls, see this thread: http://www.chiefdelphi.com/forums/sh...d.php?t=131987

[Team4169]

Thanks for the help lopsided98!

[Sperkowsky]

I wouldn't reccomend starting to install mecanum wheels now. Our team tried to install mecanums and it took us 2 weeks with this year's kop chassi. It really set us back. And its not our first time with mecanum wheels. If you try to do it now you will regret it.

[Monochron]

Originally Posted by Sperkowsky

I wouldn't reccomend starting to install mecanum wheels now. Our team tried to install mecanums and it took us 2 weeks with this year's kop chassi. It really set us back. And its not our first time with mecanum wheels. If you try to do it now you will regret it.

Just to offer a counter argument, we installed mecanums plus gearboxes in a single Saturday meeting, and we have never done mecanum before. We had everything planned and drawn out ahead of time though, that helped a lot.