Mecanum Wheel Speed Reduction

[yarden.saa]

Hi CD,
I would like to know what speed reduction do you reccomand for 6" mecanum with one cim motor per wheel.
We used to have 9:1 - 13:1 with 6" wheel in tank drive.

[Mike Marandola]

Originally Posted by yarden.saa

Hi CD,
I would like to know what speed reduction do you recommend for 6" mecanum with one cim motor per wheel.
We used to have 9:1 - 13:1 with 6" wheel in tank drive.

We will most likely go with 10.5:1 which will give us about 10.7 ft/s adjusted.

[Ben Martin]

This is totally contextual, but I look at past successful robots for years with "field dividers" (2010, 2012) that have their speeds posted to try to pick a reduction. We'll likely go 11-12 ft/s max.

[electroken]

Originally Posted by yarden.saa

Hi CD,
I would like to know what speed reduction do you reccomand for 6" mecanum with one cim motor per wheel.
We used to have 9:1 - 13:1 with 6" wheel in tank drive.

In 2013 we used 6" Vex-Pro Mecanums with one CIM per wheel. The gearbox ratio we eventually settled on was 8.45:1. If fact, we're using that robot to determine this years needs.

[Ether]

Here's the formula for vehicle free speed at motor free speed:

V = (N*pi*D)/(720*G) feet/sec

N is the motor free speed in RPM.

G is the motor revs per wheel rev (i.e. includes gearbox and sprocket or pulley reduction)

D is the wheel diameter in inches.

A rough rule of thumb¹ is to multiply V by ~80% to account for various friction forces to obtain vehicle top speed at full throttle.


¹originating I believe with JVN. The actual fudge factor depends on your drivetrain design and workmanship.