Measuring RPM

[nighterfighter]

Originally Posted by nandeeka

Another option would be for the speed to be controlled by a dial on the driver's station. You could play with the dial as needed, even during the match, if you are having issues.

Even if you do not decide to use this method in competition, it might be a good way to figure out what speed you want in the first place and then use a Bang-Bang controller or PID loop to control on-field.

You still need a way to control and verify that what your dial is setting, is actually being run on the robot.

We did do something similar in 2012 though. After our camera tracked the target, and fed the shooter a setpoint value, we had 2 buttons on our joystick that would increase the RPM setpoint by 50, or decrease it by 50.

[Tom Line]

In the case that you are unable to create a speed control routine in code, you actually can do a reasonably good job just by accounting for the battery voltage.

The major contributor to speed fluctuations of your wheel will be battery voltage, assuming that your motor and mechanical system don't change. By simply multiplying the amount your drive your shooter wheels by the % of battery voltage you can actually do a reasonably good job of keeping the motor at the same speed.

That said, if you use the "I" value in PiD, you can do a pretty good simple speed controller.