How to code a six wheel four motor drive train

Programming Support VEXcode Pro V5 Text Tech Support
1

We have a six wheel four motor drive train that seems great but it won’t go backwards and turning is weird and it won’t drive completely straight.

2

If it can’t drive straight, check to see if one of the motors isn’t working, or if wires are damaged. To fix the directions, try switching around the motor ports. Example: Left is 1,2, Right is 5,6, switch to 2,1, and 6,5. You couldn’t also switch the sides, or in this case, 6,5, and 2,1. You may need to change the forward/backward, which you can do by changing the arrow that is highlighted blue, around the drivetrain figure in between. Usually having six wheels on a 4-motor drivetrain does not affect anything, though it may become unstable if one motor has to power 2 wheels alone, and the other motor has to power one wheel(on each side). I hope this helps you!

3

Ok, before I write this, just a reminder that adding pictures of your drivetrain will get you better help in the future.

  1. Won’t go backwards
    This sounds like a code problem, and as I am not a coder, I cannot answer this.
  2. Turning is “weird”
    Can you explain what you mean by this? This could refer to a number of issues with both code and building, so more explanation would be helpful.
  3. Won’t drive completely straight
    This could be a build problem with a number of things. A motor could be dead or broken, which you can check by seeing if the port emits a solid red glow, or you could have too much friction, which can be solved by bracing your drivetrain and using bearing flats.
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4

@Daveisarobot this is vex IQ. We do not have bearing flats, and usually friction with the plastic does not result in a large difference, considering drive-straight issues. Though I would be careful adding shaft collars, as friction can still be a problem. And for “weird” turning, it is most likely a problem with mounting gears, or the motors. I have seen this on a few robots, where two wheels have a 2:1 gear ratio(on each side), while one wheel doesn’t have a gear ratio. Motors on the same side also have to be facing the same way. If they are facing toward each other, they will spin against each other, resulting in jams. I suggest looking into the details for your drivetrain to make sure everything is in the right position.

5

I apologize, I had assumed that the user was in V5RC as the tag was “VEXcode Pro V5 Tech Support” and there was no background information.

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