Talk:Hunting (engineering)

From Wikipedia, the free encyclopedia

WikiProject Physics This article is within the scope of WikiProject Physics, which collaborates on articles related to physics.
Stub This article has been rated as Stub-Class on the assessment scale.
??? This article has not yet received an importance rating within physics.

Help with this template This article has been rated but has no comments. If appropriate, please review the article and leave comments here to identify the strengths and weaknesses of the article and what work it will need.
This article has been automatically assessed as Stub-Class by WikiProject Physics because it uses a stub template.
  • If you agree with the assessment, please remove {{Physics}}'s auto=yes parameter from this talk page.
  • If you disagree with the assessment, please change it by editing the class parameter of the {{Physics}} template, removing {{Physics}}'s auto=yes parameter from this talk page, and removing the stub template from the article.

May I suggest merging this with the Hunting oscillation article. Gordon Vigurs 21:26, 8 May 2006 (UTC)

The Hunting oscillation article is rather long (and very good!) and "hunting" is also a term used more widely for self-exciting oscillations, including in electronics. But then again, there are some self-exciting oscillations, for example shimmy in automotive drivelines, that are not called "hunting". But then again, the shimmy article says: For the engineering effect, see Hunting (engineering). I think that we need an overall article on self-exciting oscillation that then unpicks the nomenclature and refers to specific detailed articles. Cutler 22:52, 8 May 2006 (UTC)
Oh, and there's aeroelasticity#flutter. Cutler 08:05, 9 May 2006 (UTC)

[edit] Self-exciting oscillation; other important instances

I totally agree with the previous suggestion to re-structure starting with an article on self-exciting oscillations. This will make it possible to explain that self-exciting oscillations are a logical consequence of systems which are described by a closed loop of time-lagged differential equations, i.e. where a change in variable N is driven by a change in variable N+1 but only after a time delay, a change in variable N+1 is driven by a change in variable N+2 but only after a time delay, .... a change in variable N is driven by a change in variable N+x but only after a time delay.

The set of articles should also point out the importance of self-exciting oscillations in fields other than engineering, for example:

  • Boom-bust cycles in economics. No doubt in practice these are partly due to herd psychology, but closed loops of time-lagged differential equations are a sufficent explanation.
  • Population booms and collapses in biology. For example back when personal computers were puny there was a text-based simulation of foxes and rabbits where an increase in the rabbit population caused a delayed increase in foxes, which caused a delayed decrease in rabbits, which caused a delayed decrease in foxes, which caused a delayed increase in rabbits, etc.
  • Possibly sunspot cycles (the sun is so vast that the propagation of imbalances and feedback mechanisms takes thousands to millions of years).

I also suggest further simple examples in engineering, for example:

  • Early central heating thermostats were guilty of hunting because they responded too quickly. The problem was overcome by hysteresis, i.e., making them switch state only when the temperature varied from the target by a specified minimum amount.
  • Steering of vehicles when course corrections are delayed. There are many examples of this, ranging from light aircraft in a strong wind (I've experienced this at the controls of a glider) to erratic steering of road vehicles by a driver who is inexperienced or drunk.

Philcha 15:44, 12 October 2006 (UTC)

[edit] Proposed merger

Fine, provided that the detailed railway engineering diagrams and calcuations go at the bottom - "hunting" is used in a wide range of contexts. Philcha (talk) 10:41, 20 April 2008 (UTC)