Motor speed control using DDC controller (PID control)

[ru4realthistime]

I agree with 4stringaddict, either your pid needs tuning or your logic is too simple. With no external load on the motor it would be no problem to control the motor speed. As soon as you set a starting rpm speed you then start your loop. It would gradully speed up or slow down to meet speed setpoint.

[BTCInstrumentation]

@ru4realthistime You can get the motor to control reasonably well by using very little proportional (gain) action and mostly integral (reset) action, but in order to prevent oscillation with such a slow controller update time you end up with pretty slow controller response. If the controller had a faster update time, you can get away with a more aggressive proportional action and much snappier response.

Dead time is the bane of feedback control.

[4stringaddict]

Dude you need to tune your PID loop!

[BTCInstrumentation]

@4stringaddict This point of the video was to show how you cannot adequately "tune" a controller with a scan time slower than the speed of the process being controlled. In a later video, I show how a "compromise" solution was found tuning integral-dominant instead of proportional-dominant, but the response to setpoint and load changes is still a lot slower than one would want for motor speed control.

Many techs think any control problem can be corrected through tuning. This is not true.