Make a point turn without drifting

We have 4-motor drivetrain, with only the two front wheels being omni wheels. Whenever we make a point turn, the center of the robot actually drifts. Any idea why? I suspect it is because of the different friction of the regular wheels and omni-wheels, but not quite sure. Thanks.

Yes it is because of the friction so I would make all your wheels Omni and if you want to put the other wheels in the middle so you can’t get pushed but can still turn from the middle of the robot

Thanks for the suggestion. We made the change and now it is better, but the turning center is still closer to the front wheel. It seems that the robot weight is not balanced.

Multiple things will affect center of rotation:

  • if any of the wheels are traction wheels, the robot will turn around the center of the traction wheels.
  • If the robot is all omnis, but only some of the wheels are driven, then the center will be between the wheels driven by motors.
  • if all the wheels are connected with chain, gears, etc, then the turning center will be the center of mass of the robot.
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