There is no set formula for advanced tuning of a PID controller, and no step-by-step process that will work in every scenario, but with an understanding of how a PID controller works, and enough practice, it is definitely possible. Once the initial values are found (by following the steps above), you can start to change the set point, and put the controller through some simulations to see how it react. The other concern with a high D value,is if there is noise or distortion of the process value feedback, the derivative may see this as a fast change in the ramp rate, and bias the output at an undesired time. If the controller starts to react in a negative way (unexpected changes in the output, poor control, or oscillation) lessen the D value until the controller is stable again.īe careful when adjusting the derivative value, as a higher value is tempting – everyone wants a smooth controller don’t they? – but too high of a derivative will start to effect the output in a negative way and “fight” what the P and I values are trying to accomplish. The purpose of the D value, is to monitor the ramp rate of the process value, and prevent it from overshooting the set point.Ĭontinue to change the set point and increase the derivative until the overshoot has been dampened to an acceptable level. Now that you have a stable PI controller, start by increasing the derivative value slowly, changing the set point, and allowing time for the controller to stabilize. But if your application could benefit from the dampening effects of the derivative, you will need to find the value that works! There are many PI controllers out there, and for certain applications, this is all that is required. I will post a video at the bottom of this article that shows these steps inside the automated PID Simulator to provide a practical example for those (like myself) who are more visual learners.įor the hands on learners, download the PID Simulator app from the Microsoft Store to put these steps into practice! Derivative Once the controller is stable, and responding desirably… congrats! you now have a working PI controller. If the controller starts to oscillate, or become unstable, adjust the I value in the opposite direction until the controller becomes stable again.
The goal of tuning the integral value, is to achieve an adequate controller response or reaction time (after the initial response from the proportional is set). Increase the integral gain in small increments, and with each adjustment, change the set point to see how the controller reacts. Always start with small steps when adjusting a PID controller, and give time between each adjustment to see how the controller reacts. Once the proportional value is found, we can start to tune the integral.
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