Holonomic drive vi with mecanum wheels

[dwodrich]

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

[Green2]

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]

Originally Posted by dwodrich

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]

Originally Posted by Green2

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]

Originally Posted by jhersh

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]

Originally Posted by Alan Anderson

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]

Originally Posted by jhersh

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]

Originally Posted by star_lancer

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).