pidtuner

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Viewing 15 posts - 1 through 15 (of 33 total)
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  • in reply to: Initial tuning values #131
    pidtuner
    Keymaster

    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:

    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.

    Cheers

    in reply to: Import Values #129
    pidtuner
    Keymaster

    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.pdf

    in reply to: PID Implementation when simulating #127
    pidtuner
    Keymaster

    That is correct, the derivative part is:
    PID_D = -(D/Ts) * (yk – ykm1);

    Just like in here

    Improving the Beginner’s PID – Derivative Kick

    in reply to: PID Implementation when simulating #125
    pidtuner
    Keymaster

    Hi, the PID algorithm for simulation is similar to this PID implementation:

    Improving the Beginner’s PID – Introduction

    in reply to: Testing #123
    pidtuner
    Keymaster

    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.

    in reply to: understanding results kiln usage #119
    pidtuner
    Keymaster

    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.pdf

    in reply to: inputing real data #117
    pidtuner
    Keymaster

    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.pdf

    in reply to: PI Controller is not working properly #114
    pidtuner
    Keymaster

    Hi,

    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:

    https://github.com/pidtuner/pidtuner.github.io/blob/master/assets/doc/PID%20Tuner.pdf

    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,

    in reply to: input data is gray out #111
    pidtuner
    Keymaster

    But the grayed out text precisely says “Use ctrl+V”, have you tried selecting the cell and then hitting ctrl+v ?

    in reply to: PID data set #105
    pidtuner
    Keymaster

    Hi,

    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,

    in reply to: Pumping model #103
    pidtuner
    Keymaster

    Hi,

    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.pdf

    in reply to: questions on criteria for the input and output #101
    pidtuner
    Keymaster

    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.

    in reply to: tuning application #98
    pidtuner
    Keymaster

    Thanks for you interest, regarding your questions:

    Yes it could, the PID being a linear system, could also be “indentified”. Actually you can exchange the input for the output column and viceversa, and a model will come up trying to match the controller dynamics.

    But only some common process models are supported by the tool. There is no “PID model” built into the software, so you won’t be able to “recover PID gains” from data with the software as-is. It could be done, but there no common use case for that, so it is not worth development time for me.

    The most common case is what is presented, model the process, then use the model to obtain good PID gains as a good starting point for tuning the control loop.

    in reply to: questions on criteria for the input and output #94
    pidtuner
    Keymaster

    It is a common question, and source of confusion. Maybe the following FAQ document can help you clarify the input/output selection:

    https://github.com/pidtuner/pidtuner.github.io/blob/master/assets/doc/PID%20Tuner.pdf

    The program is modeling the system process, not the controller. Try not to get confused by the names of the variables for any specific implementation, what the PIDTuner considers “input” is the input to the process (output of the PID). And what the PIDTuner considers “output” is the output of the process (input to the PID).

    Hope the information above makes things a little clearer.

    in reply to: What are the gains #92
    pidtuner
    Keymaster

    Hi,

    Time is always in seconds. If your PID implementation is non-standard, you are responsible of converting the PID gains to the non-standard time frame used by your PID.

    Same goes with the gains. The PID Tuner shows both Integral Gain and Integral Time because in industry either one or the other are standard. So if your PID accepts some custom transformed Integral term, you are responsible for converting it to your special PID form.

    I have been working on a presentation that I will officially release soon, hopefully with a video. Maybe this will help you clarify some practical concepts:

    https://www.dropbox.com/scl/fi/sfkz7xx7eqg7uyzu5zpwn/PID-Tuner.pptx?dl=0&rlkey=p0l03h6x6vhexmsbjhyuyqiy6

     

Viewing 15 posts - 1 through 15 (of 33 total)