Localization / Odometry using omnidirectional wheels (or Killough Platform)

Hey, I just finished building one of those!  My idea was to have a platform
able to track a flashlight beam, keeping it centered in the center of a
photodetector array.  I gotta tell you, the motion is not straight line and
smooth, in certain directions the small friction in the non-driven axes
throws off the trajectory.  I am running on carpet, you might do better on
a smooth floor.

Anyway, if you know the direction of the commanded velocity, the individual
motor commands are all K*sin(some combination of command vector angle and
fixed motor axis angle).  I also have C code written for an AVR processor,
which uses 3 PWM signals for positive commanding, and 3 more for negative
commanding.

The sensitivity of the motion to the commands means you will probably have
to run your motors with closed loop feedback.  I used home-made encoders.
I tried open loop, but each motor has different friction characteristics.

Anyway, email me and I will dump more on you than you probably want.



--
Mike Ross
The instructions said use Win98 or better, so I used Linux.