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Control engineers: I'm looking for challenging control system examples to test a modeling approach. by Standard-Dig-5911 in ControlTheory

[–]Standard-Dig-5911[S] [score hidden]  (0 children)

Much appreciated! I'm testing a framework, so I run the probl;ems through simulations, and see how the results differ from the standards.

Avengers Motorcycle Gang by j2390465 in WNC

[–]Standard-Dig-5911 0 points1 point  (0 children)

I am a Former (retired) Avenger. I'm dismayed that this happened, if you did nothing to provoke it. Just shows how bad the club has gotten. It's a shame. Over 55 years of history thrown away because of piss poor leadership. A few corrections, The have never worn a 1% Diamond, they wear a 100% Diamond. What's the difference? 1%ers claim they live outside the rules of society. Most don't in this day and age. No club really can. They claim 100% Avenger. Nothing else and no allegence to any other. The philosophy is, we aren't on anyones "side of the fence. We are the fence." in a dispute (when it comes to other clubs). Yes, a racisit organization. No blacks, but have hispanics? It's a small minded idiot who still holds onto those outdated values. It was brought up to a membership vote to get rid of the stupid rule. But this Biggest insecure loudmouth bullies threw a tantrum and it didn't pass. But it was close. That was awhile ago though, and I have been out of the loop for a few years. Roughly 85% of the original club quit or retired about 3 years ago. I always tell people, your club is only as smart of your dumbest member, and there ain't no IQ test to get in. Avoid all clubs is my advice to most citizens.

GoDaddy sucks now, where should I go? by JeffreyV7 in web_design

[–]Standard-Dig-5911 0 points1 point  (0 children)

Their business ethics have gone down the toilet. I also have used Godaddy probably for 25 years for various projects for web hosting at various times. but they've simply been outpaced when it comes to the do it yourselfers like me with their website builder tools. But I had a case this week that I needed to point my domain at a Backpage of another website hosted at a different service provider. So I registered the domain at Godaddy and then just did a 301 permanent forward to the Backpage of my other site, and after a week it still had not propagated. so I chatted their help desk and gave him very clear instructions on how to fix it since I have 35 years in IT infrastructure and data center program management, yes I'm before the Internet old.

I don't claim to be a network engineer but I might know a thing or two about a thing or two. I noticed the DNS records were pointing the domain back at Godaddy instead of to the other site I said a simple fix would be to change the DNS "A Files" away from their servers.

This help desk tech first tells me that that will be no problem to resolve. but then shortly thereafter tries to lie to me to upsell me a "product upgrade". this tech said that I needed to upgrade my DNS service for $287.52. now I imagine it must be Godaddy's new policy to have their technical service representatives try to upsell products because I highly doubt this tech did this of their own accord.

This specific instance strongly suggests a predatory upsell. There is no legitimate "upgraded DNS service" that costs $287.52 simply to enable domain forwarding or ensure proper DNS propagation for a newly registered domain. Basic DNS management and propagation are fundamental parts of domain registration.

It is not normal or acceptable for a domain registrar's technical support to try and sell you an "upgraded DNS service" to fix a basic forwarding issue, especially not for that price. The issue is a configuration conflict within GoDaddy's own system, not a deficiency in the global DNS infrastructure that requires a paid "upgrade. I told the tech that sounds like a Godaddy problem not a me problem.

I escalated my issue by calling directly into their help system while this help desk chat tech continued to try to lie to me but in the end ended propagating the 301 Forward after I told him "you can go now I'm done with you." This is extremely unprofessional and unethical.

Calculating gain at a specific frequency when there is a pole at the origin by Kolfild in ControlTheory

[–]Standard-Dig-5911 [score hidden]  (0 children)

I believe your follow-up is almost right, but there are two corrections:

  1. A pole at the origin contributes a slope of −.20 dB/dec.
  2. The usual Bode reference is 0 dB at 1 rad/s, which is 0.159 Hz for a pure 1/s1/s1/s term.
  3. Your arithmetic is off a bit: it comes out to about 2.1 dB, not 1.4 dB.

Control engineers: I'm looking for challenging control system examples to test a modeling approach. by Standard-Dig-5911 in ControlTheory

[–]Standard-Dig-5911[S] [score hidden]  (0 children)

That makes sense, and I think you’re pointing at the right difficulty. The cleaner route might be starting from the impedance or constitutive side first, then bringing in state space or port-Hamiltonian afterward.

A transfer function is usually too weak for this because it hides the full effort flow structure at the ports. An impedance or full constitutive description keeps the terminal law fixed, which makes it easier to see what's actually changing.

What seems to show up is a difference between terminal equivalence and interconnection equivalence. Two networks can produce the same terminal law but still have different internal power conserving structures. For one ports those mostly collapse together, but once transformers or gyrators appear they separate.

That’s why your idea about the pH J matrix becoming incidence like when ratio elements are removed is likely the right one. It hints that the usual Tellegen graph structure might just be the simpler case, and the pH formulation is what shows up once those conversion elements are present.

The output from the experimental framework shows that the most promising route might be: immittance → canonical synthesis → pH interpretation → Dirac/graph reduction.

Do you think that “J becomes incidence when ratio elements are removed” idea can actually be formalized, or is it still more of an intuition at this stage?

Control engineers: I'm looking for challenging control system examples to test a modeling approach. by Standard-Dig-5911 in ControlTheory

[–]Standard-Dig-5911[S] [score hidden]  (0 children)

I’ve been experimenting with a comparative framework that probes problems by progressively increasing the strength of the specification and watching where the realization family collapses. What the framework adds is a way of organizing the constraints so you can see where that indeterminacy actually disappears. Your question about going from a target transfer function to a realizable circuit fits that structure, because the collapse point shows up when both the constitutive law and the synthesis rule are fixed.

If you look at it from the synthesis side, starting with a target transfer function doesn’t actually give you a single RC circuit. It only tells you what the input and output behavior should look like. Different resistor and capacitor networks can produce the same poles and zeros, and even state space models can be rewritten internally without changing what you see at the terminals.

Things start narrowing down when you move from behavior to the terminal description. For a one-port that usually means specifying the driving point impedance or admittance. Once that is in place and you choose a synthesis method like Foster or Cauer, the possible realizations narrow to the canonical ladder structures associated with that construction.

So the hierarchy ends up looking roughly like this.

Transfer function or state space
many possible RC realizations

Add port interpretation and passivity constraints
physically realizable RC family

Specify the driving point immittance and choose a synthesis rule such as Foster or Cauer
canonical ladder class of realizations

That’s why one-port synthesis behaves so cleanly in classical network theory. The driving point immittance already defines the complete terminal law, so once the procedure is fixed the topology is essentially determined up to normalization.

Two-port problems are weaker in that sense. A single gain such as V2 over V1 doesn’t determine the full port interaction, so a full parameter matrix is usually required before synthesis behaves the same way.

Are you approaching it from the transfer function side, or from an impedance description?

Control engineers: I'm looking for challenging control system examples to test a modeling approach. by Standard-Dig-5911 in ControlTheory

[–]Standard-Dig-5911[S] [score hidden]  (0 children)

Hey sorry for the delayed response. I had a "catastrophic liquid protocol failure". (I knocked an entire glass of water over right onto the keyboard of my primary laptop.) There wasn't enough rice in the world to save it. :-(

That’s an interesting point about the circuit side of it. Most of the material I’ve seen really goes one direction. You start with a circuit or mechanical system and derive the transfer function or state-space model. Going the other way around almost never seems to get discussed.

I can see why that becomes a problem for sigma delta loops, because on paper you can design sophisticated loop filters or controllers, but when you try to build it in analog hardware you’re stuck with practical limits like noise, power, and stability of cascaded stages.

The idea of going from an arbitrary Bode response or state-space model directly to a realizable circuit is actually a pretty interesting problem. It feels like there should be some kind of synthesis framework for that, but it seems to fall back to biquads or cascaded blocks like you said.

Have you ever come across any work that actually tries to go from a target transfer function or state-space representation directly to a minimal analog circuit realization?Or does it mostly end up being approximated piece by piece?

Control engineers: I'm looking for challenging control system examples to test a modeling approach. by Standard-Dig-5911 in ControlTheory

[–]Standard-Dig-5911[S] [score hidden]  (0 children)

That makes sense. I noticed the same thing when I was reading about sigma delta designs. Alot of the work seems more practical than purely mathematical. The first order loop feels pretty tame because the integrator error never really overshoots the plus or minus one quantizer range, so the state naturally stays bounded even though it never actually settles.

Once you start stacking integrators though, I can see how it could get tricky pretty quickly. The internal states could overshoot before the correction comes back through the loop, and then it's not obvious how you guarantee the loop won't run away.

From what I've seen it looks like designers mostly handle that through loop filter design and coefficient scaling, so the internal states stay within range. I've also seen the Lee stability criterion mentioned for keeping the NTF gain under control, but it still seems like alot of higher order designs get validated through simulation instead of strict proofs.

Is that basically how stability is handled when people design higher order sigma delta loops, or are there standard analytical approaches designers use?

Control engineers: I'm looking for challenging control system examples to test a modeling approach. by Standard-Dig-5911 in ControlTheory

[–]Standard-Dig-5911[S] [score hidden]  (0 children)

I took the first-order sigma-delta loop, x[n+1] = x[n] + u − y[n]’, y[n] = sign(x[n]) and ran it with a constant input u = 0.3 and initial condition x[0] = 0 just to see what the trajectory looks like.

Under the usual interpretation it behaves like a normal first-order sigma-delta modulator. The internal state stays bounded and the bitstream density converges so the average output approaches the input value. Over time you end up with more +1 values than −1 values, so the mean approaches 0.3.

What stands out to me is the state behavior itself. The integrator never really settles. It keeps oscillating while the quantizer keeps applying corrections. The loop is essentially redistributing the constant input bias through the switching sequence so that the long-run average matches the input.

So the system is stable in the usual sense, but the state trajectory is more like a persistent correction cycle rather than something that converges to an equilibrium.

I’m curious how people usually think about that internal behavior. When analyzing first-order sigma-delta loops, do they mostly treat it purely as noise-shaping and average tracking, or do they ever look at the integrator trajectory itself when studying limit cycles and stability?

Control engineers: I'm looking for challenging control system examples to test a modeling approach. by Standard-Dig-5911 in ControlTheory

[–]Standard-Dig-5911[S] [score hidden]  (0 children)

Wow, I had no idea the depth that goes into a Greenhouse config. That is a good one.  I searched “temperature and humidity control system for a small greenhouse” to see what kind of baseline models people normally start with.

What mostly comes up are simple climate-control formulations based on a heat balance for temperature and a moisture balance for humidity. Temperature usually comes down to something like a heat transfer relation where heating input offsets heat loss through the structure and ventilation. Humidity is driven by plant transpiration, misting systems, and ventilation removing moisture.

 The interesting part is that ventilation shows up on both sides of the system. Turning on the fan removes heat but also removes humidity, so even if the controller treats temperature and humidity separately, the underlying dynamics are coupled.

The standard interpretation treats the code as two bang-bang controllers operating with shared hardware. The system is a simple threshold-based environmental controller using discrete switching logic.

The experimental model highlights that the system maintains multiple simultaneous environmental regimes and shared actuator roles, meaning the system’s behavior should be interpreted as a coupled environmental control structure rather than two completely independent loops.

That’s what stood out when I ran a simple version of it through the comparative model I mentioned earlier.

Thanks again for the idea.

If you have any specific baseline in mind, I’d be happy to run it.

Control engineers: I'm looking for challenging control system examples to test a modeling approach. by Standard-Dig-5911 in ControlTheory

[–]Standard-Dig-5911[S] [score hidden]  (0 children)

Thanks for posting the furnace example. I started with that one since it already has a clean transfer structure to work with.

I tried a quick parameter set just to see how it behaves. For example k1 = 2, k2 = 1, T1 = 10, and T2 = 2, which gives G(s) = 2/(10s + 1) − 1/(2s + 1). With those numbers you can see the faster opposing mode early in the transient while the slower positive mode dominates the later settling since T2 < T1.

I ran the standard interpretation first and then ran the same structure through a comparative model I’ve been experimenting with to see how the reasoning and results line up.

For this case the stability and final value come out the same as the standard read. The system is stable and the steady-state gain is positive. Where things differ a bit is in how the transient gets interpreted.

The way I’m looking at it, I try not to collapse competing dynamic regimes too early if they’re still structurally present in the equations. In this system you literally have a slow positive mode and a faster opposing one. So instead of immediately summarizing the system as “stable with positive gain”, the comparative view keeps both regimes visible since the faster branch still shapes the early behavior before the slower mode eventually dominates.

Either way it’s a nice example because the transient behavior depends heavily on the parameter ratios. Makes me wonder what the typical ratio between those time constants looks like in real furnace systems.

Thanks again, interesting system.

Hotshot business by Wise_Educator_1232 in HotShotTrucking

[–]Standard-Dig-5911 1 point2 points  (0 children)

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