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Unread 23-01-2011, 03:13
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Re: Calibrating Mecanum Drive

Quote:
Originally Posted by efoote868 View Post
Imagine your robot has four mecanum wheels, with two dead motors on opposite corners, and two live motors on the different corners.

You use the joystick to try and go straight in an axis. Because there are only the opposite two motors powering the robot, the robot will spin as it moves. Since the gyro is compensating for the spin, the robot will still be attempting to move in that same direction. The two live motors will begin to output less and less.

The robot will continue to spin until the two dead motors are perpendicular to the axis that you're trying to move the robot on, and the two motors that work will be lined on that axis. The robot will no longer move, because the gyro in field centric drive will tell the working motors not to move, and tell the dead motors to go full power.


Now, imagine that instead of two dead motors, they only work at 90%. The same process will occur, except an equilibrium will be found sooner. This equilibrium requires no extra code to compensate for the biased motors.


I hope that makes sense? Otherwise I might have to try some of my mad paint skills.
Wow, that's pretty cool. It might be clearer if you say that the gyro does compensate. Also, while you are reaching that equilibrium, doesn't the robot get out of alignment (in the x direction, I know it would rotate)?

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Unread 23-01-2011, 03:21
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Re: Calibrating Mecanum Drive

After taking a look at the vectors, there won't be rotation if the two live motors have equal strength, the robot will just move on a diagonal.
Woops .
This won't be the case though, so I think you'll still get the effect.
The correct way to go about doing this is to compensate for the rotation though .
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