Mecanum Trouble

[Dawg2T4]

Just for some clarification, when you say swap the Front Right and Back Left motors, do you mean within the HolonomicDrive.vi, or is there a place within the teleop.vi to do that? Our Build session starts in about half an hour, so we can tell how well it worked then.

[Ether]

Originally Posted by Dawg2T4

Just for some clarification, when you say swap the Front Right and Back Left motors...

Just to be clear, I said swap the motor commands, not the motors. This can be accomplished in software, or in hardware by swapping the motor wires (while leaving the motors themselves unmoved). Swapping the physical motors themselves would serve no purpose here.

do you mean within the HolonomicDrive.vi, or is there a place within the teleop.vi to do that? Our Build session starts in about half an hour, so we can tell how well it worked then.

I don't do LabVIEW. Do whatever you have to do so that the motor commands are swapped. What that means is this:

• the command that presently is going to the FrontRight motor should be sent instead to the BackLeft motor, and
  
  
• the command that presently is going to the BackLeft motor should be sent instead to the FrontRight motor

I think that can be accomplished in the Begin vi, wherever you assign the CAN addresses for the 4 motor locations. If there are any LabVIEW gurus reading, please chime in here.


PS: you never did answer this post. It's important; it determines which motor commands should be swapped.

[Dawg2T4]

Sending the robot a clockwise signal makes all of the wheels turn inward towards each other. When we made the change for the motor commands all it did was changed the strafing to the all in/out command and changed what we wanted the rotation to be to strafing.

[Dawg2T4]

Here's a screenshot of our code, just to reiterate, this is the code that has forward, backward, and strafing correct but has a problem with rotating. When we try to rotate clockwise the robots wheels all run inward (meaning, the two front wheel go backward and the two back wheels go forward) and when we try to rotate counterclockwise the wheels go outward (the two front go forward and the two back go backward).

Begin

[IMG][/IMG]

Holonomic

[IMG][/IMG]

Teleop

[IMG][/IMG]

[Ether]

Originally Posted by Dawg2T4

Sending the robot a clockwise signal makes all of the wheels turn inward towards each other.

If that's the case, the change you should have made, according to previous posts, is to swap the FrontLeft and BackRight motor commands. Is that what you did?

If not, undo what you did and make the correct change.

Originally Posted by Ether

PS: you never did answer this post. It's important; it determines which motor commands should be swapped.

Originally Posted by Ether

What he needs to do is swap the FrontRight and BackLeft motor commands (if the rotate clockwise command is causing the wheels to turn "outward") or swap the FrontLeft and BackRight motor commands (if the rotate clockwise command is causing the wheels to turn "inward").

Originally Posted by Ether

If a rotate clockwise command causes all the wheels to run outward you need to swap the FrontRight and BackLeft motor commands.

If a rotate clockwise command causes all the wheels to run inward you need to swap the FrontLeft and BackRight motor commands.

[REDBARON]

Originally Posted by Ether

If that's the case, the change you should have made, according to previous posts, is to swap the FrontLeft and BackRight motor commands. Is that what you did?

Yes that is what we have done, we have tried it swapped and not swapped and neither ways work, when swapped if we give a pure clockwise command both sides run inward, sorry if I am repeating things, I just want to make sure everything is clear,
-Jack

[Ether]

Originally Posted by Dawg2T4

Sending the robot a clockwise signal makes all of the wheels turn inward towards each other. When we made the change for the motor commands all it did was changed the strafing to the all in/out command and changed what we wanted the rotation to be to strafing.

What change did you make?

Looks like the change was not done properly.

Please post LabVIEW png snippet of before & after code.

[REDBARON]

Originally Posted by Ether

What change did you make?

Looks like the change was not done properly.

Please post LabVIEW png snippet of before & after code.

Before:
http://s278.photobucket.com/user/Daw...tml?sort=3&o=1

After:
http://s278.photobucket.com/user/Daw...tml?sort=3&o=0

[Ether]

Originally Posted by Dawg2T4

Sending the robot a clockwise signal makes all of the wheels turn inward towards each other. When we made the change for the motor commands all it did was changed the strafing to the all in/out command and changed what we wanted the rotation to be to strafing.

I don't know what change you made, but it didn't swap the suggested motor commands. The behavior described above is not consistent with the change suggested.

Swapping the FL&BR motor commands should have had no impact at all on the strafe command. And it should have corrected the rotate behavior.

This is assuming that you have provided accurate test data about wheel direction in response to fwd/rev and strafe left/right as shown in the attached chart.

Would you please post the before and after code as a LabVIEW PNG snippet as an attachment here on CD.

[REDBARON]

Sorry, had some problem with posting the picture of the code. It's updated now with a link to each instance of the code.

[REDBARON]

Originally Posted by Ether

Swapping the FL&BR motor commands should have had no impact at all on the strafe command. And it should have corrected the rotate behavior.

Strafing worked fine, it was during rotation (specifically clockwise) that both sides turned inward.

[Ether]

Originally Posted by Dawg2T4

When we made the change for the motor commands all it did was changed the strafing to the all in/out command and changed what we wanted the rotation to be to strafing.

Originally Posted by Ether

Swapping the FL&BR motor commands should have had no impact at all on the strafe command. And it should have corrected the rotate behavior.

Originally Posted by REDBARON

Strafing worked fine, it was during rotation (specifically clockwise) that both sides turned inward.

????

[REDBARON]

Originally Posted by Ether

????

Sorry there was a miscommunication. With the motors FL & BR switched strafing and forward/backward work fine but rotation does not work, with them not switched, using rotation buttons causes strafing, and strafing fights itself.
The miscommunication was that the "change" in question was not clearly defined, as we had already left yesterday with that change made and the rotation still wasn't working. Sorry about that.

[Cecil]

Hold on a second, I think I know what's going on. On the "Open 4 Motor.vi", there are actually 4 terminals to invert motors. It looks like you have both of the bottom ones set to true and the top two unwired (which defaults to false). This would mean that Both your front left and front right motors are inverted, but not the other ones. Your inversions should match on sides, not front to back. I have attached a photo that should explain it a bit better.

Try going back to the default code (run the wires directly from the joystick axes to the holonomic vi) and see if inverting the correct motors fixes everything for you. If you push the joystick forward, and the robot moves backwards, switch the inversions to the right side instead.

[REDBARON]

We've sorted out the rotation problems by coding in a button that switches to arcade and using that to rotate, however we have noticed that strafing remains on the x-axis. but the y-axis causes rotation. we would like to resolve this and have the y-axis remain the same and the x-axis change