How are you implementing traction control?

[dtengineering]

Originally Posted by Vikesrock

And yet Dave has stated that he has gone down the length of the field and back in 12 seconds. This would appear to be pretty solid evidence that the published coefficients are not correct and you should try to perform a test to determine the actual CoF to get the correct maximum acceleration.

I've laid out the steps we used here. When we did those calculations we assumed that the entire 36 pound weight of the trailer would be borne by the trailer wheels, which is not an entirely correct assumption, some of the trailer mass will contribute to normal force on the robot and thus improve traction a bit, but even if you run the numbers for just the robot (no trailer), it seems that FIRST has published a (I've been waiting to use this.... sorry)... coefficient of fiction.

Jason

<Edit>
re-running the numbers without the trailer, or with 100% of the trailer weight on the tongue and contributing to the normal force of the robot, is should still take at least seven seconds each way... unless there is some great bouncy rebound off the end driver station wall. These calculations are also based on 100% regolith travel... Dave may have been using the carpet at the edge of the field to get up to speed. Perhaps we have been underestimating the influence that the carpeted boundary will have on the game. </Edit>

[Jared Russell]

Limiting the commanded acceleration of your drive wheels can prevent wheel slippage - but ONLY in the absence of unaccounted external forces. If you are running into the arena walls and other robots, this assumption is no longer valid.

In other words, this type of traction control would not help in a pushing match.

[XXShadowXX]

This is how we're doing it...

Your wheel speed is given by a magnetic rotation sensor (what controls your volume in your car). This is compared to to integrated accelerator value, over 20ms. Find the difference, correct the motor speed, use some ifs to determine if your driver is accelerating your decelerating. Then out put the correct speed of the robot to the wheel, plus a tiny fraction of acceleration energy, or none if you want to hold constant speed...