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Unread 30-01-2017, 14:05
Waz Waz is offline
Strategy and programming mentor
AKA: Steve
FRC #2357 (System Meltdown)
Team Role: Mentor
 
Join Date: Feb 2013
Rookie Year: 2009
Location: Raymore, MO
Posts: 20
Waz is an unknown quantity at this point
Re: Most Graceful Mecanum Robots?

In 2015 when I was mentoring team 4561 in Durham NC, we used two joysticks and field relative drive (could switch to robot relative if desired).

As with many such designs, one stick was for movement. We would move, relative to the field, in the direction the stick was pushed and at a speed relative to the deflection of the stick.

While we used the second stick for rotation, I think we did it a bit differently than most. We would use PID control to rotate the robot to the field relative direction that the stick was pushed. It was not just rotate CW or CCW. It would rotate CW or CCW depending on which way was the smaller angle (always less than or equal to 180 degrees) to the desired field relative angle.

This made it easy to move toward a location on the field and by the time you were there, be pointing in the direction you wanted. For example, to move somewhere straight up the field and be pointing to the right, push the movement stick forward and the rotation stick straight right.

I would not say we quite got it perfect, for example the drivers tended to have to push the rotation stick to an angle a bit past where they wanted the rotation to stop, but it was pretty slick.

Thanks,
Steve
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