pic: Did Somebody Say Defense Game?

[JamesCH95]

Originally Posted by wilsonmw04

so adding three motors doesn't increase torque? interesting.

Adding an extra motor per side does increase the theoretical maximum available torque. However, traction limitations and battery limitations do not allow that torque to be fully utilized.

[Deke]

Originally Posted by JamesCH95

Adding an extra motor per side does increase the theoretical maximum available torque. However, traction limitations and battery limitations do not allow that torque to be fully utilized.

Correct, you would have to be able to feed the motor the extra current to increase the torque. So basically you increase the system stall torque by increasing motors, but can you feed it the extra current?

If two drivetrains exactly the same in traction, weight, gear ratios were in a push off/breaker cook race and the only difference is the motor count (lets say a 4 cim versus a 6 cim), the 4 cim drivetrain will pop its breakers faster. The 6 cims will have less current going through the individual 40a breakers (total flow divided by 6 instead of 4), and slightly less through the main breaker (because they should be running at a slightly higher efficiency).

My assumption why people pop breakers with 6 cims faster than 4 cims is because they think they can push while geared high, when really both systems are limited by their breakers. So you would need the correct gearing in either case to be a good pushing robot.

[JamesCH95]

I think that a brown-out and re-set of the cRIO is a very likely drivetrain induced failure. Not just the breakers blowing. I don't know which one, 6cim or 4cim, would be more likely to trigger a brown-out, though I think a brown-out or low-voltage reset is much more likely than blowing a main breaker.

Full disclosure: I have not a lot of experience blowing 40A breakers, or main breakers for that matter. I've always geared transmissions on robots a little conservatively, prioritizing robustness over ultimate performance. One robot team 95 made had issues with that, a full 4-wheel swerve in 2003, that could drain a battery down to the point of brown-out half-way through a match.