paper: Take-Back-Half Shooter Wheel Speed Control

[Ether]

Originally Posted by z_beeblebrox

For shooter speed control, what are the advantages of PID or take-back-half control over bang-bang control? It seems like bang-bang control provides the shortest spin-up time, as the motor is run at full power, and, if run with a fast enough update time, accurately holds shooter speed in a small tolerance.

If:

1) your motor is directly connected to the shooter wheel (so there is no gearbox free play and minimal "drivetrain" friction), and

2) your wheel is reasonably balanced (so excessive vibration does not cause rapid deceleration of the wheel when power is removed), and

3) your speed feedback has good resolution and minimal phase lag (as would a properly coded counter object using the getPeriod() method), and

4) your shooter has sufficient moment of inertia (most do), and

5) you run the algorithm fast enough (20ms or faster)

... then it's hard to beat bang-bang control.

Even if some of the above criteria are not met, bang-bang can be the best method, on a case-by-case basis depending on your design.