Hacker News: pidtuner

PID Tuner: A Practical Guide

pidtuner — Wed, 04 Aug 2021 07:07:33 +0000

Article URL: https://www.slideshare.net/RudolfKalman/pid-tuner-a-practical-guide-249874901

Comments URL: https://news.ycombinator.com/item?id=28058123

Points: 2

# Comments: 1

New comment by pidtuner in "Ask HN: Share your side project"

pidtuner — Wed, 04 Aug 2021 07:02:52 +0000

https://pidtuner.com Tune Your PID Controller

PID Tuning: A Practical Guide

pidtuner — Wed, 28 Jul 2021 09:09:25 +0000

Article URL: https://www.slideshare.net/RudolfKalman/pid-tuner-a-practical-guide-249874901

Comments URL: https://news.ycombinator.com/item?id=27981766

Points: 2

# Comments: 0

New comment by pidtuner in "PID Controller for controlling the number of servers in a data-center"

pidtuner — Mon, 05 Jul 2021 07:45:54 +0000

https://pidtuner.com can help with that

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Thu, 27 May 2021 11:29:05 +0000

Not to control, but to compensate. This is what the I action in the PID does, compensate for un-modeled disturbances

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Thu, 27 May 2021 08:31:18 +0000

We can move this discussion here : https://github.com/pidtuner/pidtuner.github.io/issues/11

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Thu, 27 May 2021 08:27:56 +0000

The trick is that, even though the augmented state is uncontrollable, you still use it in the predictions, so the MPC algorithm can still compensate for it. Take a look at the before-last graph in the paper, see how that technique improves predictions after learning the real-time disturbances.

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Thu, 27 May 2021 08:25:44 +0000

The code is C++ code, It could be ported to an MCU if there is a fairly recent C* compiler (C11+). But the algorithms are quite expensive, there are multiple matrix inversions, the size of the matrices been as large as the data you put in into the tool. typically between 500 and 10000 data points.

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Thu, 27 May 2021 08:06:22 +0000

That's literally what you can do with the tool. Did you clicked the "Get Started" button?

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Thu, 27 May 2021 08:05:08 +0000

You are right, but the problem of a possible analogous "Machine Learning Theory" is that machine learning problems are highly nonlinear, and control theory has only been "solved" for linear problems. It we could solve nonlinear control that could immediately be applied to machine learning.

“Linear systems are important because we can solve them.” — Richard Feynman

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Thu, 27 May 2021 07:55:00 +0000

I suggest to take a look to the canonical PID implementation of the Arduino library. It includes a simple but effective anti-windup mechanism:

http://brettbeauregard.com/blog/2011/04/improving-the-beginn...

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Thu, 27 May 2021 07:52:23 +0000

The problem with many adaptive control techniques is that is very difficult to prove the closed loop stability and performance margins, because such systems are highly nonlinear and we do not have yet the mathematics to provide simple guarantees (for example, I would not get into an aircraft where the control systems have not been rigorously, mathematically, designed)

The integral problem of LQR and MPC is indeed not the first topic discussed on textbooks, but there has been a solution for that for year, called "disturbance model". You you can have an "adaptive MPC" following some design procedures. Check out this reference:

https://folk.ntnu.no/skoge/prost/proceedings/ifac2014/media/...

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Wed, 26 May 2021 16:45:56 +0000

The tuning rules from Skoge provide very decent robustness margins. (https://folk.ntnu.no/skoge/publications/2001/tuningpaper_ren...)

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Wed, 26 May 2021 16:44:16 +0000

True to that, but this tool hopes to provide an educated initial guess.

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Wed, 26 May 2021 16:43:14 +0000

Maybe the youtube videos help with this? https://www.youtube.com/channel/UCkRD7FztiFOdX50BUsOkcSQ

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Wed, 26 May 2021 16:41:28 +0000

Thanks. It is C++ code using Armadillo for linear algebra and BLAS/LAPACK subroutines. Source code is a bit messy, but will try to clean it up and put it on a different repo when I find the time.

The most complex part is the identification algorithm, which uses this algorithm: https://math.stackexchange.com/questions/1428566/fit-sum-of-...

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Wed, 26 May 2021 15:24:35 +0000

That is true, that is why there is a slider in the tool that allows you to trade-off performance for robustness. The bode plot is also an indication on how the closed loop performs in frequency domain, so you would normally choose different tunings according to specific use cases (e.g. some frequency response for tracking and a different one for just regulating)

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Wed, 26 May 2021 15:20:39 +0000

The tuning algo is the easiest part, the tool uses this one: https://folk.ntnu.no/skoge/publications/2001/tuningpaper_ren...

The difficult part is the identification algorithm, that is the challenging part, to accept all sorts of user data for all sorts of processes.

There is no monetization, users can be patreons, by a mug, a shirt or simply help by sharing the site. I miantain it on my free time.

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Wed, 26 May 2021 15:04:26 +0000

I did, 3 or 4 times, but was ignored until somebody else did. I don't know how the HN algorithms work.

New comment by pidtuner in "Tune Your PID Controller"

pidtuner — Wed, 26 May 2021 14:30:37 +0000

For anybody interested in a simple introduction of PID control, I recommend watching Brian Douglas' videos https://www.youtube.com/playlist?list=PLUMWjy5jgHK20UW0yM22H...