Drivetrain partial inversion

VEX V5 Technical Support
1

So, we were using the vexcode v5 wizard to attach our drivetrain. (We made the base of the Stryker Hero bot as a starting point). It works fine, but we run into EITHER the forward-reverse being inverted OR the left-right being inverted. We are using the controller configuration where axis 3 is forward/back and axis 1 is left/right.
What can we do to fix this? The team really only has any experience using blocks for coding, btw.

We have tried the following:
Inverting drivetrain in the setup.
Switching motor cables
Driving backwards.

2

We had simmilar issues in the past. It was usually solved by swaping the ports around. For example swaping right and left or front and back.

3

That was one of the things we tried. This is the stryker bot, so only a 2-motor drive, using chains and sprockets to make it a pseudo-4 wheel drive.

4

If I recall, can’t you change motor rotation in the brain? Maybe I’m thinking of iq… but still worth checking.

1 Like
5

I think there’s a misunderstanding of what the issue is. I’ll try to bullet point it.

When going Straight, it behaves as it should:
When we push forward, the wheels spin forward.
When we pull backwards, the wheels spin backwards.

When turning, it behaves inverted.
Signaling right causes the right wheel to spin forwards and the left to spin backwards, making the robot turn left.
Signaling left causes the left wheel to spin forwards and the right to spin backwards, making the robot turn right.

Switching how the cables are connected only switches the problem; making the turning correct, but the forwards/backwards inverted.

Switching the drivetrain setup causes the same thing as switching the cables.

Switching the motor directions on the brain causes the same thing as switching cables or drivetrain setup.

I am seriously at a loss as to how the signals are getting mixed up.

6

I would say do what turbo dog said in past years this has worked for my team

7

Does this mean you flipped the drivetrain direction? This is used depending on if your left and right motors are pointing toward each other or away.
image

8

That is exactly what it means, although we weren’t using a gyro. Do you think that might help?

9

Aaand, connecting a gyro sensor (which we’d not used on anything other than a TestBed in my PLTW class last year before) solved the issue. =D Aah, the sweet feeling of success.

10

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