Drivetrain drift

So when driving our robot, it slightly drifts to the left. Manageable at low speeds, but at high speeds it is a big issue. We literally didn’t do anything to cause it. Left it over the weekend, then booted it up and it started drifting. We have no idea what the issue could be. Maybe a motor issue? We replaced motors and that didn’t fix it but still could be. We just have zero clue what it could be and it could be an issue with autonomous.
Any idea what a fix could be?

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There are a lot of different potential causes. Give some of these threads a read and see if any of these things fix it:

https://www.vexforum.com/search?expanded=true&q=robot%20not%20driving%20straight

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none of those really seem to help because we did check for friction (what most of them said to do) and it seemed to be fine. Not a code issue because I didn’t change the driving code at all.

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I had the same problem and I fixed it by recalibrateing my controller sticks

how do you do that?

20 char

Go into controller settings and press recalibrate

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Ohh. I’ll have to try that tomorrow. Thank you.

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We had this problem earlier. If your motors are quick swap, disconnect them all and push it and see if the problem persists. if it does, you definitely have a friction problem. If not, the controller stick recalibration could fix it. And if your motors aren’t quick swap and the controller recalibration doesn’t work, you should probably disconnect them anyway.

alright, thanks. Seems like a common issue then?

it’s really just a build issue. Due to the small variance in parts and assemblies, you could build two sides exactly the same and one will have more friction because one (or many) spacing(s) is off by a millimeter or less. Ours was friction, and just adding and removing a washer here and there did the trick

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We had a problem with motors running at different rpm’s. Try testing each motor with just a shaft, a gear and a pin. Count the number of revolutions in a given time span (minute, etc) - the number of times the pin passes a mark. If the same quality, you should get same RPMs in the same time. We had 10 new motors; found two within 5 RPMs and used those for drive train (85 and 90RPMs in one minute. We had new motors as much as 40 RPM different in the same time frame - caused the same issue you are experiencing.

If you’re talking about pins, im assuming you’re vexiq. Haven’t really heard of this problem in v5 personally, but its possible

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Im going to test these things today. Hope it works out.

Last year my team had the same problem, just loosen the left side of the drivetrain a bit and it should work.

You can find friction in the drive motors by comparing watts used… no screwdriver needed.

general overview

motor_watts = 0
motor_count = 0
begin loop
if “watt reading from motor” >.1 then
motor_watts=motor_watts+“watt reading from motor”
motor_count=motor_count+1
display motor_watts/motor_count to brain…
end loop

repeat for all 4 drive motors

i could easily be wrong but it might be the overall build quality, building with alignment is very important and a squaring tool has been very useful for my team.

thats a possibility. My teammate did attach it wonkily.