I'm doing some reading on control systems at the moment and when reading pages on classical control methods, some sites state that they are preferred in industrial applications.

I've read that simple SISO systems such as temperature control for air conditioning can be achieved faster and more efficiently using classical methods. Through my reading, I've generally only found smaller-scale applications for the classical methods. I was just wondering if there are any larger-scale situations in the industry that benefits from using the classical methods over other methods.

Thank you in advance.

  • $\begingroup$ Accountants make engineers go for cheap, why spend on fancy.... $\endgroup$
    – Solar Mike
    Apr 5 at 19:32
  • $\begingroup$ what do you mean by "modern" here? what do you mean by "scale"? (dimensional scale or system order / complexity) $\endgroup$
    – Pete W
    Apr 5 at 21:24
  • $\begingroup$ Maintainability, being "good enough" and the ease with which they can be implemented are probably important factors for the prevalence of PID controllers in the industry. $\endgroup$
    – fibonatic
    Apr 6 at 12:08


This is not an answer, its more a praise to an unsung facet of the genius of a much celebrated architect. The title of the question (minus the word control) reminded me of an experience I wanted to share (which is relevant is a very generic way).

When I visited Barcelona (sometime in the previous millennium), I had already a few years of experience in numerical methods and Finite Elements. I had the chance of visiting one of Gaudi's museums. What really impressed me at that point (and in many ways humbled me afterwards upon reflection), was looking at a relatively small corner something like this.

enter image description here

Until then, I had not read or heard until then about Gaudi's, and its use of strings (I was and in many ways still more attuned with digital tools).

Upon reading closely on the exhibit's tag, I realised that this was a way of predicting what is best way to use material in order to maximise the structural performance. I.e. someone was using string, balls/masses and gravity as a an analog computer to optimise and at the same time give shape to a structure the size of a cathedral.

enter image description here

So probably to to me that is the best example of a rudimentary (I would never describe it as classical because I've never actually seen it since or heard of it being used), that I would be certain it performs better that any of the "modern" alternatives.

enter image description here

rope, weights and gravity.

enter image description here

  • $\begingroup$ How does it work? $\endgroup$
    – DKNguyen
    May 6 at 3:22
  • 1
    $\begingroup$ @DKNguyen you take a piece of rope and place weights and you form the shape you want. Then you mentally invert the shape and ( provided you used a reasonable approximation of the weights) and you can use the shape you obtained, as a close to optimal shape for compressive loading. $\endgroup$
    – NMech
    May 6 at 7:19
  • $\begingroup$ The rope is non stretchy? $\endgroup$
    – DKNguyen
    May 6 at 8:41
  • $\begingroup$ Νο it, doesn't have to be. the added weights only need to be proportional/analogous to the masonry load. In a way you are limited in the elastic region. $\endgroup$
    – NMech
    May 6 at 11:18
  • 1
    $\begingroup$ I think I sort of get it. You just have to tune the weights and length of the string so everything is under tension with the shape you want, right? Because if anything is slack or out of balance the shape will be messed up. I guess you just cut string lengths based on the wireframe of your desired shape to begin with $\endgroup$
    – DKNguyen
    May 6 at 18:56

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