[KrazyCarl92]

Did some testing last night. We have a drivetrain which is geared to 8.8 fps in low gear and 22.6 fps in high gear with 4 CIMs. We are using KOP wheels (Andymark says .95-1.0 CoF) and the robot weighs about 145 pounds with battery, bumpers and all. We are aware this gearing is not absolutely ideal, but using 6 in. wheels and looking at COTS options meant we were going for whatever retrofits best to 6 in. wheels out of designs made for 4 in. wheels.

We set the robot up against the wall and drove into it to test our traction limits. Our robot is traction limited in low gear. Didn't watch the voltage drop in this case since I fully expected it to be traction limited.

The high gear when starting statically was not traction limited. The voltage reading on the driver station dropped just below 8 Volts and then hovered between 7.5 and 8.5 Volts while the robot's wheels failed to turn.

We then tested dynamically going into the wall such that the wheels would be spinning when we hit the wall in high gear. The observed effect is that we were traction limited in this case. The wheels spun while the robot pushed against the wall not moving. The observed voltage readings were an initial drop below 8 Volts, then a quick recovery to between 9.5 and 11.5 Volts. If you have suggestions for other things to test with this set up I would be glad to give stuff a try.

One thing I have done is use Weighted Objective Tables to evaluate the trade-off between "Time to Distance" and motor/circuit breaker abuse. Basically it's an objective way of determining which gear ratios are reasonable for a given strategy. If your strategy requires driving long distances across the field often, go with time to travel 25 feet. If the game dictates that the longest distance a team will reasonably be able to travel often in a sprint is 10 feet, use that. Then consider current draw under certain conditions and how long it may take your breakers to trip in the worst case scenario. Weight them accordingly. It's a good way to objectify this inevitable trade-off in gearing decisions, especially since all of these things are quantifiable with decent models. This can also be used to objectify motor allocation and shifting in addition to gearing choices.