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Unread 21-01-2017, 06:23
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bEdhEd bEdhEd is offline
Design and Drive Team Mentor
AKA: Frank E.G. Shiner
FRC #0701 (The RoboVikes)
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Re: Ball Centering Video (Team 846)

Really interesting results. I didn't expect the double wheel to shift the ball off center.

Now do you think with how most backings of shooters will have a central angle less than 180 degrees, that the flywheel profile may be negligble? These tests seem to have results that can be observed after several rotations, i.e. the robot has a theoretical shooter backing of central angle greater than 360 degrees.

Considering our intitial conditions being the position of the ball center relative to the center of the flywheel, these conditions seem to change significantly in a backing exceeding 360 degrees, but do they change enough in a backing of central angle less than 180 degrees, or even 270 degrees?

If I play and pause the video for each wheel and pause after about 180 degrees of rotation, I don't notice much difference in the shift of the ball until several more rotations, so does my hypothesis of negligibility between wheel profiles hold true in a backing of less that 180 degrees?

Or am I wrong, and the shifting is more dramatic in a smaller angle backing when using higher speeds where the ball may slip on the wheel while being accelerated as opposed to being perfectly gripped in the slower speed of the small scale model?

Also, a foam ball was used in the scale model. I'd like to know if there are different results using more rigid and less "grippable" balls, or even balls with more intertia or irregular surfaces. For example, it would be neat to see the differences between a small foam ball, a ping pong ball, and a golf ball. Also, does the amount of compression affect the rate at which the ball shifts? There may be plenty of variables associated with this.
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Last edited by bEdhEd : 21-01-2017 at 07:42.
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