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Vex FlyWheel Syncronization 
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Joined: Thu Nov 29, 2012 9:32 pm
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Post Vex FlyWheel Syncronization
For this years vex game nothing but net, my team is using a flywheel mechanism to launch the balls. That is where we have two wheels spinning outwards to launch a ball. Much like a baseball pitching machine.
One problem that i foresee us having is one motor spinning faster than the other and throwing off our shot. We have motors with the built in encoders on the flywheel motors to help with this problem, but I'm not really sure of the best way to solve this problem in code. I was thinking of just having it count the rotations of each motor and then lower the power of one by 10 or so if the rotation count is greater but that wouldn't be a good solution because there is no way to know for sure if that adjustment would be suitable.
How could i have the code using the encoders to maybe calculate the speed of the motors and adjust the power accordingly or just continuously raise or lower the power until the two motors are equal. Does anyone know the best way to tackle this problem? Any feedback will be much appreciated.

Thanks
Robert Brown
7361 Team Captain


Thu Oct 08, 2015 12:08 am
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Joined: Thu Dec 01, 2011 12:07 am
Posts: 151
Post Re: Vex FlyWheel Syncronization
Consider a mechanical connection between the rollers such as gears, shaft, or chain.


Thu Oct 08, 2015 11:34 am
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Post Re: Vex FlyWheel Syncronization
CARBOT wrote:
Consider a mechanical connection between the rollers such as gears, shaft, or chain.

We were thinking about doing that. It would just involve us changing around a lot of stuff and we just wanted to see if there was an easier solution before we started rebuilding the launcher.


Thu Oct 08, 2015 12:53 pm
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Post Re: Vex FlyWheel Syncronization
Quick Solution:
You could try PID control for a more precise speed. Have a look at (http://www.education.rec.ri.cmu.edu/pre ... hp_PID.pdf) for more info.

Quick Note:
Just a quick question what speed is your flywheel going and what type of encoder are you using. This is important since the Optical Shaft Encoder can only measure 1,133 rpm. While integrated encoded motor will have no problem since they measure the motor speed not the flywheel speed (i assume you have geared your flyweel).

Kind regards,
Asim Poptani
King Henry VIII


Thu Oct 08, 2015 2:04 pm
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Post Re: Vex FlyWheel Syncronization
The link you provided for PID control goes to the main webpage of carnegie mellon. I need help with PID control as well so yeah.


Thu Nov 19, 2015 9:14 pm
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Post Re: Vex FlyWheel Syncronization
Sorry link got broken.

http://www.education.rec.ri.cmu.edu/products/cortex_video_trainer/lesson/3-6IntegratedEncoders2.html[newlink]


Sat Nov 21, 2015 2:26 am
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Post Re: Vex FlyWheel Syncronization


Lets say I have 2 motors on each wheel and both motors are spinning one axle using small gears. Would I need to have an integrated encoder on both motors and will the PID still work properly?


Fri Dec 11, 2015 10:56 am
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