Forum Replies Created
February 16, 2023 at 4:51 pm in reply to: how to detect the dead time #137
Here are a few tips:
It all boils down to having good (noise and perturbation free) step response data.February 16, 2023 at 12:08 pm in reply to: how to detect the dead time #135
Your data does not show any delay, the process is responding immediately to an input change.
If you want the tool to detect a dead-time, it must be able to see the dead time.
I.e. if your process had a dead-time, it would have a flat output during the dead-time after a change in the input.
February 2, 2023 at 5:46 pm in reply to: What are the gains #133
Regarding the gains, I show all 5 because some PID implementations use gains, other implementations use times. Just plug in the values that your PID implementation requires. Wikipedia is always your friend.
Maybe this helps:
https://github.com/pidtuner/pidtuner.github.io/blob/master/assets/doc/PID%20Tuner.pdfNovember 28, 2022 at 11:45 am in reply to: Initial tuning values #131
Hey, happy to hear it worked for you with ease.
As you can imagine, the algorithm is rather complex, but generally speaking, it consists of:
- a series of both linear and nonlinear system identification techniques to identify the models based on your data.
- skogestad’s IMC rules for PID tuning based on the models (https://folk.ntnu.no/skoge/publications/2003/tuningPID/more/tuningpaper_reno-2001/tuningpaper_06nov01.pdf)
The PID tuning rules are just given as a tuning starting point. The valuable information are actually the models, you can use any tuning rules over the models to achieve whatever you want with your PID.
CheersNovember 15, 2022 at 6:52 am in reply to: Import Values #129
Hi, have you had a look at the following guide? If so, is it still unclear?
https://github.com/pidtuner/pidtuner.github.io/blob/master/assets/doc/PID%20Tuner.pdfOctober 14, 2022 at 6:46 am in reply to: PID Implementation when simulating #127
That is correct, the derivative part is:
PID_D = -(D/Ts) * (yk – ykm1);
Just like in hereOctober 12, 2022 at 9:31 am in reply to: PID Implementation when simulating #125
Hi, the PID algorithm for simulation is similar to this PID implementation:
Glad to hear the PDF solved some of your questions.
Regarding the size of the increments, it should be large enough, such that the output signal can be clearly distinguishable from noise.
In other words, the size of the increments should be large enough such that the output signal displays a clear curve that the pidtuner tool can identify, but not too large so you avoid damaging your hardware.
As a rule of thumb, I always try to split my operating range in 3 to 5 levels.April 25, 2022 at 2:00 pm in reply to: understanding results kiln usage #119
Hi, thank you for using pidtuner.
Looking at your test data, it seems that the step response test has not been done properly. Please look at the following guidelines to make a proper step response:
https://github.com/pidtuner/pidtuner.github.io/blob/master/assets/doc/PID%20Tuner.pdfApril 7, 2022 at 4:46 pm in reply to: inputing real data #117
Hi, thank you for using pidtuner.
To help us help you better, it would be useful if you share your pidtuner project link with us.
In the meanwhile, take a look at this presentation to check if you have done all the steps correctly:
https://github.com/pidtuner/pidtuner.github.io/blob/master/assets/doc/PID%20Tuner.pdfMarch 28, 2022 at 6:27 am in reply to: PI Controller is not working properly #114
Thank you for using pidtuner. Looking at your data, it seems that your step test is not done correctly.
First, the input data does not seem correlated to the output data throughout the experiment, see slide 9 (“Common Mistakes …”) of the following presentation:
Second, it seems you are saturating your actuator, since the output looks like it achieves a constant growth speed instead of a natural growth curve. Maybe try a smaller step change.
Hope this information helps,March 17, 2022 at 8:04 pm in reply to: input data is gray out #111
But the grayed out text precisely says “Use ctrl+V”, have you tried selecting the cell and then hitting ctrl+v ?December 9, 2021 at 9:46 am in reply to: PID data set #105
We are happy you found the FAQ and tool useful. Let us know if you have an specific question in mind or if you need help with an specific data set that you are willing to share.
Best,November 29, 2021 at 4:07 pm in reply to: Pumping model #103
Yes, it seems you need to modify the gains as you suggest. Also it seems your implementation does not have Derivative action, so when you choose a model in de pidtuner app, make sure is a first order model as to make sure Derivative action is zero.
Take a look to this presentation if you want more confidence that you are doing PID tuning correctly:
https://github.com/pidtuner/pidtuner.github.io/blob/master/assets/doc/PID%20Tuner.pdfNovember 2, 2021 at 10:46 am in reply to: questions on criteria for the input and output #101
The error is the setpoint (SP) minus the process output (PV). The output column must contain the process output.
Every system (process and PID) has an input and an output. That is why it can be confusing. The PID has as input the error (SP-PV), and the control variable (CV) as output. The process has the CV as input and the PV as output.
What the PID tuner need as “input” is the CV and as “output” the PV. Because it is the input and output of the process. Hope this is clearer.