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-   -   Holonomic drive vi with mecanum wheels (http://www.chiefdelphi.com/forums/showthread.php?t=80169)

dwodrich 14-01-2010 09:50

Holonomic drive vi with mecanum wheels
 
Does anyone know if the Labview Holonomic drive VI works with the mecanum wheels?

Green2 16-01-2010 00:53

Re: Holonomic drive vi with mecanum wheels
 
As I understand it, the control of mecanum drive is different than holonomic. Check out this paper for the math behind both drive systems.

http://www.chiefdelphi.com/media/papers/1836

Barry

jhersh 17-01-2010 20:50

Re: Holonomic drive vi with mecanum wheels
 
Quote:

Originally Posted by dwodrich (Post 898878)
Does anyone know if the Labview Holonomic drive VI works with the mecanum wheels?

Yes... the ambiguously named holonomic drive VI is designed for use with mecanum wheels, not omni wheels. Sorry for the confusion. Also note that there is a bug in the documentation for the Rotation input terminal... The detailed help says that the units for this input is in degrees per second. This is incorrect. The input has the range -1.0 to 1.0. 1.0 means spinning clockwise at full speed and -1.0 is counterclockwise.

jhersh 17-01-2010 20:54

Re: Holonomic drive vi with mecanum wheels
 
Quote:

Originally Posted by Green2 (Post 900222)
As I understand it, the control of mecanum drive is different than holonomic.

Holonomic is a class of motion capability. Mecanum wheels are a specific design that can achieve holonomic motion. In other words, mecanum drive is one type of holonomic drive.

Alan Anderson 17-01-2010 22:37

Re: Holonomic drive vi with mecanum wheels
 
Quote:

Originally Posted by jhersh (Post 901308)
Yes... the ambiguously named holonomic drive VI is designed for use with mecanum wheels, not omni wheels. Sorry for the confusion.

In my experience, the programming for both mecanum and omniwheel systems is the same.

jhersh 18-01-2010 00:13

Re: Holonomic drive vi with mecanum wheels
 
Quote:

Originally Posted by Alan Anderson (Post 901365)
In my experience, the programming for both mecanum and omniwheel systems is the same.

True... but it does assume that you have mounted your omni wheels at 45 degrees in the corners of your robot for the direction parameter to have the same meaning. Given that this is usually more difficult than mounting them along the 4 sides, it seems less likey that the VI as supplied will apply directly to a typical omni wheel design.

If your omni-wheeled robot is using 3 wheels at 120 degrees, your drive system is still holonomic, but this VI can't help you. Also, swerve drive systems are holonomic but could not be controlled by this VI. That's why I don't care for the naming of it.

star_lancer 18-01-2010 13:44

Re: Holonomic drive vi with mecanum wheels
 
Quote:

Originally Posted by jhersh (Post 901413)
True... but it does assume that you have mounted your omni wheels at 45 degrees in the corners of your robot for the direction parameter to have the same meaning. Given that this is usually more difficult than mounting them along the 4 sides, it seems less likey that the VI as supplied will apply directly to a typical omni wheel design.

If your omni-wheeled robot is using 3 wheels at 120 degrees, your drive system is still holonomic, but this VI can't help you. Also, swerve drive systems are holonomic but could not be controlled by this VI. That's why I don't care for the naming of it.

So do you need to have your mecanum wheels mounted on the corners at 45 degrees for the holonomic VI to work? I'm just a little confused.

jhersh 18-01-2010 16:01

Re: Holonomic drive vi with mecanum wheels
 
Quote:

Originally Posted by star_lancer (Post 901661)
So do you need to have your mecanum wheels mounted on the corners at 45 degrees for the holonomic VI to work? I'm just a little confused.

No... if you are using OMNI wheels (with the rollers at 90 degrees to the wheel axle) then you need them at 45 degrees in the corners.

If you are using mecanum wheels, the rollers are at 45 degrees to the wheel axle, and should therefore be mounted inline on each side (just like you would do for tank drive with 4 independent motors using regular wheels).


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