For the benefit of people who are rebuilding their flywheels or doing FRC Stronghold and are not familiar with VEX forums, here are some threads you may want to read for the additional information on optimizing flywheel launcher.
First of all, there is a continuation of the measurement noise discussion and some more graphs from my experiments in the moving average thread.
Also, related to the flywheel mass are the discussions about improving firing rate: 16957, 17410, and you simply cannot miss wild speculations around 4664Cās mystery launcher.
In addition to understanding importance of handling measurement noise in the velocity readings for good flywheel speed control, you may want to think about delays in the control loop that affect stability of the algorithm and how using different motor ports influence that.
Once you done with the theory, you could take a look at the hybrid flywheel PID code, which we field tested and it seem to be working quite well.
@technik3k Is there any way you could finish the āSecrets to a low friction launcherā series? Iām still really interested in how you guys use the High strength bearing with something else to reduce friction on the flywheel.
I will certainly ask the team to make another video. I couldnāt promise anything as they are busy re-configuring the robot for the next competition.
However, I could say that the proper alignment plays just as important role as the parts you choose for the bearings. The special bearings we made using old torque gears from 393 motor are, probably, only necessary if you want to build something exotic like a single-motor full-court shooter (see Dec 23 post). Otherwise a pillow or a regular bearing should work just fine.
Once again, make sure everything is properly aligned, axles are not bent, and there is no metal to metal friction anywhere.
Hi, I am currently designing a ball launching machine using counter rotating wheels, and I was wondering if you could help me out.
In order to determine the RPM required for each wheel, I have use v = omega * r, taken the ball speed to be an average of the tangential speeds of each wheel. Would this be correct? Also, how would the contact area affect this? Surely the larger contact area, the more force would be produced but would I be able to calculate this? Any advice would be appreciated.
Hi, one more question, as each wheel is powered by an individual dc motor, would I calculate the motor torque using T = I * alpha where I is the moment of inertia of the wheel (1/2 * m * r^2) and alpha is the angular acceleration in rad/s? Thanks in advance
Yes, your formula for RPM determination is correct.
The contact area does not affect performance of the launcher much. If the contact area between ball and the launcher was perfectly flat then it would cancel itself out from the formulas. The force of compressing the ball and the surface material, that it interacts with, will affect performance of the launcher.
Most of the threads this season measure ball compression in distance units. For example, 0.5" compression would mean that 4" ball was squished to 3.5" when it was going through the launcher.
Yes, this is the right formula. You have only 1 motor per flywheel, but if you had (n) motors then they would produce (n) times the torque, and if you have a gears between motors and the flywheel that increase omega (k) times it will reduce torque coming from the motors (k) times.