pic: 2826 Halonomic Drive Prototype

[Jared Russell]

Originally Posted by EricH

Clockwise, O contact pattern on the ground, lines are vectors in a clockwise turn, arrows are vertical component of the vector:

\../ (^v)
/..\ (^v)

Clockwise, X contact pattern on the ground, lines are vectors in a clockwise turn, arrows are vertical component of the vector:

/..\ (^v)
\../ (^v)

Eric,

The problem is not with the vertical components of the vectors but rather with the horizontal. Also, I think that what I call "X" and what you call "X" are different.

So, using your notation:

Orientation of torque vectors - Vertical components - Horizontal Components

What I called "O":
/..\ (^v)(>>)
\../ (^v)(<<)

No problem here. The vertical components want the robot to turn CW, and so do the horizontal.

What I called "X":
\../ (^v) (<<)
/..\ (^v) (>>)

Problem! The vertical components want to turn CW, while the horizontal components want to turn CCW. The two cancel each other out as long as the roller friction is negligible.