Talk:Nonlinear control

Untitled
This page would definately need an example of an application or real-world problem associated with subject.

Linear vs. Linear "Time Invariant"
I am going to remove a line dealing with the sinusoidal input/output relationship of linear systems. In general, sinusoids are eigenvectors only of linear, "time-invariant" systems. Of course, we should not limit this property to time--we could also consider "space-invariance." The point that should be made is that some linear systems can be described completely by the behavior of their eigenvectors. We shouldn't limit ourselves to translation-invariant eigenvectors, and we certainly shouldn't claim that all linear systems have translation invariant eigenvectors. Fermiecat 15:42, 12 July 2007 (UTC)

WikiProject class rating
This article was automatically assessed because at least one WikiProject had rated the article as start, and the rating on other projects was brought up to start class. BetacommandBot 10:00, 10 November 2007 (UTC)

Non-linear or Nonlinear?
I don't see why the title of the article is Non-linear instead of nonlinear - I suggest that we rename the page to keep the consistency with nonlinear systems. Jiuguang Wang (talk) 13:09, 1 April 2008 (UTC)
 * There's nothing wrong with either name. "Non" is a valid English prefix, and so you're allowed to do it either way. Because "l" looks so much like "I" or "i", sometimes it's more clear to use "Non-linear." The style rule is to add hyphens when it improves clarity. It's not clear that nonlinear systems shouldn't have its title changed (it should certainly have its content changed). &mdash;TedPavlic (talk) 01:12, 3 February 2009 (UTC)

Fundumental question
Lead paragraph: "Nonlinear control is a sub-division of control engineering which deals with the control of nonlinear (and possibly time-variant) systems."

What then is the sub-division of control engineering which deals with the control (of possibly linear systems) by non-linear controllers? --Tennenrishin (talk) 13:10, 31 January 2009 (UTC)
 * Please review the recent changes. Does that work for you? If not, edits are welcome. (aside: this page (and many of the other control pages, especially the ones that involve nonlinear control) needs a complete rewrite sometime in the near future; someone should just be WP:BOLD and blow it away) &mdash;TedPavlic (talk) 01:09, 3 February 2009 (UTC)

Really bad article
This is a rotten article. It's coverage of the subject is very uneven, giving a few aspects WP:UNDUE weight. All it has for description is a collection of bullet points. It doesn't define clearly what a NL control system is, or why the distinction is important, or mention that NL systems are harder to solve than linear systems, or have an overview of the mathematical techniques used such as Liapunov stability theorem, limit cycle theory, Poincare maps or describing functions, or linearization by perturbation theory. It has an image of only one type of NL control system, a linear plant-nonlinear control, while the most common type is a nonlinear plant, linear control.

And as is common in technical articles, some mathematically-inclined editor, instead of improving the article's coverage, has chosen to show off by adding a detailed mathematical analysis of one small problem, the Lur'a problem, and one "deep" peripheral mathematical theorem, the Frobenius theorem, without any information about its application to the subject or its importance.

Just sayin'.... -- Chetvorno TALK 22:34, 25 April 2014 (UTC)

globally uniformly asymptotically stable equilibrium of the system
I know nothing of this field, but should the current phase "globally uniformly asymptotically stable equilibrium of the system" not instead read "globally uniform asymptotically stable equilibrium of the system"? Otherwise one might expect "globally and uniformly ...". &mdash; MaxEnt 03:49, 5 June 2022 (UTC)