Obtain transfer function of a system and simulate it with a PID controller

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Discussion Overview

The discussion revolves around the process of obtaining a transfer function for a system and simulating it with a PID controller. Participants explore the feasibility of off-line simulations versus on-line tuning, particularly in the context of potentially non-linear systems.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Homework-related, Mathematical reasoning

Main Points Raised

  • One participant expresses interest in tuning a PID controller either on-line or by obtaining the system's transfer function for off-line simulation, noting uncertainty about the system's non-linearity.
  • Another participant questions the rationale behind not tuning the controller on the actual system, suggesting that if the system is well understood, it would be more effective to test it directly.
  • A suggestion is made to use Simulink in MATLAB for the simulation process.
  • A request is made for assistance in generating a sine or cosine wave signal with increasing frequency during the simulation.
  • A participant identifies the requested signal as a chirp and provides a MATLAB command for generating it, while also inquiring about changing the amplitude of the wave.
  • Further assistance is sought for generating a sine wave with increasing frequency and constant amplitude.

Areas of Agreement / Disagreement

Participants express differing views on the preferred method for tuning the PID controller, with some advocating for on-line tuning and others considering off-line simulation. The discussion remains unresolved regarding the best approach.

Contextual Notes

Participants have not reached a consensus on the effectiveness of off-line versus on-line tuning, and there are unresolved questions about the specifics of signal generation in simulations.

Who May Find This Useful

Individuals interested in control systems, PID tuning, simulation techniques, and signal generation in MATLAB may find this discussion relevant.

cristian1500
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I want to tune my PID controller. For this I could either do this on-line using the controller on the system, or I could try to obtain the systems' transfer function and then simulate it off-line together with the PID controller to tune it to the desired behavior. I suspect the system is non-linear but I'm not sure.

Do you have any experience with off-line simulations of a system control loop? Is it possible to obtain a systems' transfer function?

Here is a first approach to the problem:
http://www.facstaff.bucknell.edu/mastascu/econtrolhtml/Model/Model5.html
 
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I can't image why you would NOT want to tune your controller on the system it's going to control. If you know the system well enough to produce some sort of input signal that simulates it, why not just enter the parameter data into the controller then run your system and see how well you really knew it.
 
I would use simulink in matlab.
 
can anyone tell me how can i generate a sine or cos wave signal with increasing frequency as the simulation time proceeds
 
You mean a chirp?
Using what software? In Matlab you would -not surprisingly- use the "chirp" command...
 
@f95toli: thanks for ur reply
using simulink!
i know we can use a chirp for cosine ,but how can i change the amplitude of the wave
and i also need to genrate a similar sine wave with increasing freq and constant amplitude
can you help me out
 

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