Designing out brownouts?
 

Going into my fifth and final year of FRC I am looking to push my team into new and unfamiliar areas. For me that starts with a strong drive train. These last few years my team has been usings and exploring custom gearboxes but every one has had 4 cims. This year game permitting I hope to have 6 cims.

While using JVN calc for speeds I am unnerved by what each motor is drawing at stall, 60-80amps each. Easily enough to blow the main breaker if held for more than a moment.

We use Victor SP motor controllers for the drive train, can we implement current control to prevent this? Also for the none programmer I am could the pseudo code be explained?

Also can anyone explain to me the exact correlation between high current draw and voltage drop?

Re: Designing out brownouts?
 

Here's a pretty good paper to read on the advantages of the 6 CIM drivetrain like you mentioned, and it includes a nice little algorithm to attempt to limit current and avoid brownouts.

Re: Designing out brownouts?
 

For the voltage drop, it's as simple as V=IR. The wire, speed controllers, PDB, motor itself, etc all have internal resistance, and the voltage drop between the battery and the motor is proportional to the current. In addition, as the motor gets hotter, it's resistance increases.

This is also where shifting and driver training come into play. A low gear is essentially a mechanical solution to the current problem.

Is there a performance advantage to a 6 CIM drive? Yes. But because of many of the issues you've mentioned, it's not just a matter of designing those motors into the powertrain. Things like battery health and charge, wiring, etc are necessary to realize the full potential of the extra power. This is compounded by the brownout protection that didn't exist last time a lot of teams ran six CIM drives. Could the effort towards solving these problems be better used elsewhere on the robot (assuming your goal is competitive success)? I think the answer for most teams is yes, but YMMV.