Performance Characterisitics Given a Zero in the System

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Discussion Overview

The discussion centers on determining performance characteristics such as rise time, peak time, percent overshoot, and settling time for a second-order system with a unit step input. Participants explore analytical methods for deriving these characteristics without relying on simulation tools like MATLAB.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant presents a specific open-loop transfer function and seeks analytical methods to determine performance characteristics.
  • Another participant suggests finding the inverse Laplace transform of the system's response and using calculus to derive the necessary relationships, noting that this can become complex.
  • A later reply emphasizes the importance of understanding how zeros influence transient behavior in systems, indicating that this knowledge can aid in predicting performance characteristics.
  • Another participant recommends consulting a textbook that derives relationships for second-order systems using calculus, suggesting that this could provide a clearer path for the original poster.

Areas of Agreement / Disagreement

Participants generally agree on the complexity of deriving performance characteristics analytically and the usefulness of understanding the role of zeros in system behavior. However, there is no consensus on a single method or approach, as multiple strategies are discussed.

Contextual Notes

The discussion highlights the potential challenges in deriving analytical relationships, including the complexity of inverse Laplace transforms and the calculus involved. There may be missing assumptions regarding the specific conditions of the system being analyzed.

Who May Find This Useful

This discussion may be useful for students or professionals interested in control systems, particularly those looking to deepen their understanding of second-order system dynamics and performance analysis without relying solely on simulation tools.

Kuriger9
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I have the equations to determine the rise time, peak time, percent overshoot, and settling time for a generic second-order system with no zeros in the system. Given a unit step input for the open-loop transfer function G(s)=(s+1)/(s2+2s+1) how do I analytically determine the performance characteristics (aside from using MATLAB)?


Thanks in advance!
 
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In general, you're going to have to find the inverse Laplace transform of the response you're interested in and do a bit of calculus to derive relationships for rise time etc. These can quickly become unwieldy, so you often find that people just simulate the response and tune the parameters to fit their specifications.

That's not to say they're doing it blind though. If you read up a bit on how zeros affect the transient behavior of systems, you can get the hang of predicting their influence.
 
milesyoung said:
In general, you're going to have to find the inverse Laplace transform of the response you're interested in and do a bit of calculus to derive relationships for rise time etc. These can quickly become unwieldy, so you often find that people just simulate the response and tune the parameters to fit their specifications.

That's not to say they're doing it blind though. If you read up a bit on how zeros affect the transient behavior of systems, you can get the hang of predicting their influence.




Thank you this certainly helps!
 
If you really want to find those relationships, I recommend you follow a text where they derive them for a second order system using calculus.

Then you can try to do it for the system you're interested in and get help with the specifics here if you get stuck.
 

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