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-   -   Mecanum Trouble (http://www.chiefdelphi.com/forums/showthread.php?t=133581)

Alan Anderson 28-01-2015 17:39
Re: Mecanum Trouble
 
Swap them in Begin, making the inputs to the Open 4 Motor Drive match the actual motors on the robot.

Dawg2T4 28-01-2015 18:15
Re: Mecanum Trouble
 
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 28-01-2015 18:29
Re: Mecanum Trouble
 
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 28-01-2015 18:42
Re: Mecanum Trouble
 
Quote:
Originally Posted by Dawg2T4 (Post 1435353)
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.


Quote:
Originally Posted by Ether (Post 1435320)
PS: you never did answer this post. It's important; it determines which motor commands should be swapped.
Quote:
Originally Posted by Ether (Post 1435080)
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").
Quote:
Originally Posted by Ether (Post 1435049)
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.

Ether 28-01-2015 19:40
Re: Mecanum Trouble
 
Quote:
Originally Posted by Dawg2T4 (Post 1435353)
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 28-01-2015 19:40
Re: Mecanum Trouble
 
Quote:
Originally Posted by Ether (Post 1435370)
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

REDBARON 28-01-2015 19:56
Re: Mecanum Trouble
 
Quote:
Originally Posted by Ether (Post 1435388)
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 28-01-2015 20:12
Re: Mecanum Trouble
 
1 Attachment(s)
Quote:
Originally Posted by Dawg2T4 (Post 1435353)
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 28-01-2015 20:19
Re: Mecanum Trouble
 
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 28-01-2015 20:24
Re: Mecanum Trouble
 
Quote:
Originally Posted by Ether (Post 1435405)
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 28-01-2015 20:33
Re: Mecanum Trouble
 
Quote:
Originally Posted by Dawg2T4 (Post 1435353)
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.
Quote:
Originally Posted by Ether (Post 1435405)
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.
Quote:
Originally Posted by REDBARON (Post 1435416)
Strafing worked fine, it was during rotation (specifically clockwise) that both sides turned inward.
????

REDBARON 28-01-2015 20:38
Re: Mecanum Trouble
 
2 Attachment(s)
Here are the attachments, in order before and after.

REDBARON 28-01-2015 20:45
Re: Mecanum Trouble
 
Quote:
Originally Posted by Ether (Post 1435423)
????
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 28-01-2015 21:00
Re: Mecanum Trouble
 
1 Attachment(s)
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 30-01-2015 18:32
Re: Mecanum Trouble
 
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


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