paper: Cyber Blue 234 - Swerve Implementation Presentation

[Ether]

Originally Posted by Chris Fultz

The reference mainly applies to mecanum wheels. for these wheels to work and allow the robot to slide side to side, the small rollers must be low traction.

Same with an Omni wheel - they are made to slide side to side, so they have to be low traction.

With a swerve drive, since the whole wheel set rotates to change direction, a higher traction wheel material can be used. In these systems, the wheel does not slide across the floor.

For how did we learn this, it was just through analysis of the different systems and an understanding of how and why they work.

Hi Chris,

Thanks for responding.

A mecanum vehicle does not require low traction tread surface on the rollers in order to move sideways. The sideways motion of the vehicle is accomplished by the combined action of the wheels turning and the rollers rolling. It does not depend on "sliding" at the roller-to-floor contact interface.

If you have access to a good university library, an excellent discussion of this is provided in chapter 3 of Introduction to Autonomous Mobile Robots by Siegwart and Nourbakhsh. You can also probably get the book via inter-library loan through your local community library.

I've posted a short paper here...

http://www.chiefdelphi.com/media/papers/2390

... which derives the inverse kinematic equations which show how to properly program a 4-wheel mecanum vehicle's individual wheel speeds in order to accomplish any desired combination of simultaneous vehicle motions (fore/aft; sideways; rotation) without scrubbing the wheels against the floor.


An explanation why a mecanum vehicle has less traction than a standard-wheel vehicle (even if both vehicles have the same tread material) is given here:

http://www.chiefdelphi.com/media/papers/2385


I'd be interested in discussing this with you if you disagree after reading the book or the papers.



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