2015: Year of the Mecanum

[GeeTwo]

Originally Posted by Mecanum Wheel

Hi Aedan. Just for future reference, it's spelled mecanum. It's an easy mistake to make.

Is anyone using 6 inch mecanum wheels with CIMple boxes? We will be and are going for ~11 ft./s.

That sounds way too fast! A CIMple box has a gear ratio of 4.67:1 (14:3) which is an "80%" speed of 5310 rpm * 2 * pi radians/rev / 60 sec/min * 3 / 14 * 3 in / 12 in/ft * 0.8 = 29.8 fps! Get some 2-stage gearboxes!

If you want to calculate a gear ratio, a CIM-driven robot with an 80% efficient drive train, 1:1 gearbox and a 1" diameter wheel would go 18.5 fps (if it were on some sort of weird rail that let this happen, or it were an offset gearbox). Multiply by your diameter in inches and divide by the gearbox ratio to get your 80% speed. To calculate a gearbox ratio, multiply by your diameter in inches and divide by the desired speed. In your case, that would be 18.5 * 6 / 11 = 10.1:1. As you seem to be shopping at AndyMark (and so do we), the 10.7:1 TB Mini looks like a good option.

[Mecanum Wheel]

Originally Posted by GeeTwo

That sounds way too fast! A CIMple box has a gear ratio of 4.67:1 (14:3) which is an "80%" speed of 5310 rpm * 2 * pi radians/rev / 60 sec/min * 3 / 14 * 3 in / 12 in/ft * 0.8 = 29.8 fps! Get some 2-stage gearboxes!

We will be using sprocket reductions.

[idahorobot]

Originally Posted by Tom Line

Absolutely. It's not terribly complicated either. After all your meCHanum motor set speeds are calculated, mix in a component from the gyro useing a PID. Only do this when the driver is using the strafe functions. Disable it when he is turning.

Easy Peasy.

Can we use the gyro on the RoboRio? OR I should say how well will the gyro work on the RoboRio?

[alopex_rex]

Originally Posted by idahorobot

Can we use the gyro on the RoboRio? OR I should say how well will the gyro work on the RoboRio?

IIRC the RoboRio doesn't have a built-in gyro, only an accelerometer.

[idahorobot]

Oops Thanks