pic: 2605 Mecanum Drive

[JamesCH95]

Originally Posted by Twins Inc.

I imagine that the bot with the higher gear ratio, bot A, (or lower fps) would have more control and less acceleration than B. But also more heating, and power consumption because of more motor use/rpm. Or am I mixing things?

You're mixing things.

To answer Ether's quiz - A will be superior to B in every performance metric he listed with the possible exception of pushing force, as that would depend greatly on the CoF of the wheels against whatever traction surface they're on.

Assuming the theoretical drives are using CIMs, this chart explains almost everything:



The motors' efficiency is maximized in the 'high speed' regime (left-hand side of the plot), where it will operate when paired with a higher-reduction transmission and no voltage reduction. This means that the input electrical power is converted into more mechanical power and less waste heat as compared to lower-speed operation. There is also more available 'power under the curve' when full-speed operation is allowed, which results in improved drive acceleration (what some might call 'response').

Furthermore, the higher-reduction gearbox that allows full-speed motor control will have better drive resolution. By reducing the allowed output voltage of the motor controller the total range of allowed outputs is reduced.

In my opinion it is very poor design practice to limit motor voltage as a means of maximum speed control, especially when gearing options are so readily available. Not utilizing the motors' full speed capabilities handicaps the drive, which is arguably the most important system on every robot.