Linear system which is time independent

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Discussion Overview

The discussion revolves around the control of time-independent systems and their representation through algebraic equations, particularly in the context of modeling systems like boilers. Participants explore whether such systems can be effectively controlled using various types of controllers, despite the absence of differential equations in their models.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether a time-independent system can be controlled via a controller, assuming a model of the form c = a*u, where u varies with time.
  • Another participant requests clarification on the terms "controlled" and "a controller" to better understand the context of the discussion.
  • A participant provides an example involving a boiler model, suggesting that controlling temperature based on an algebraic equation (Q = m*c*delta(T)) is possible, despite lacking its differential form.
  • Further clarification is sought regarding the controllability of a solution derived from a differential equation, specifically whether a discrete PID controller can be applied to a time-dependent output like position.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the definitions of control and the applicability of controllers to time-independent systems. Multiple viewpoints are presented without a clear consensus on the feasibility of controlling such systems.

Contextual Notes

The discussion highlights limitations in understanding the terms used and the nature of the equations involved, particularly the distinction between algebraic and differential forms. There is also an indication that the solutions provided in Excel may not fully capture the dynamics of the systems being modeled.

gegitur
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hi guys,

can a time independent system model be controlled via a controller?
I am assuming that we can obtain a solution for the model at each sample time, just assume that the model is of c= a*u type, i.e u is input which varing with the time. I am confsed...
 
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It would help if you would say what you mean by "controlled" and "a controller".
 
HallsofIvy said:
It would help if you would say what you mean by "controlled" and "a controller".

let say, a an algebraic equation representing a boiler model, what you give is voltage and the output is temperature. Is it possible to control the temperature by just knowing its algebraic form of equation, which is not differential equation but its approximation to an algebraic form.

more clearly,

Q=m.c.delta(T) --> the equation in diff. form would be dQ/dT=m.c.dT/dt,

what I have is something like Q=m.c.delta(T),for this eq. the heater input for example, u, is varying with the time. (I am supposing that I have many many approximated formulas, not their differential forms and I can't have differential form of them)

thank you for your help..
 
hi guys,

I have sorted out the problem, and this solution has led to a new question. We have had a buch of equations in excel form where there were only time dependent. They were in fact a solution to a differential equation. for exmp:(1)..> dx/dt =x_{2dot}+ a*x_{dot}+c*x and what we have had in excel docs were the solution to above diff. eqns, i.e.(2)..> x(t)=exp(-a*t)+ blah blah..., are the second eq. controllable using a discrete PID or any type of controller? the input to the 2nd equation is time only and the output is let say position.
 

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