Scalar in terms of multiple variables, Nyquist & Bode Plot

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SUMMARY

The discussion focuses on converting a scalar control system into a discrete equivalent model using MATLAB, specifically addressing the challenges of representing a scalar without traditional state-space matrices A, B, C, and D. The user seeks assistance with stability analysis using the Nyquist plot and obtaining frequency response via the Bode plot. It is confirmed that even a scalar can be represented with 1x1 matrices for A, B, C, and D, enabling the user to proceed with their analysis.

PREREQUISITES
  • Understanding of control systems and scalar representations
  • Familiarity with MATLAB for control system analysis
  • Knowledge of Nyquist and Bode plot techniques
  • Basic concepts of discrete-time systems and stability analysis
NEXT STEPS
  • Research how to derive discrete-time models from continuous-time scalars in MATLAB
  • Learn about stability criteria using the Nyquist plot for scalar systems
  • Study the process of generating Bode plots in MATLAB for frequency response analysis
  • Explore examples of control systems represented by 1x1 matrices
USEFUL FOR

Control engineers, students studying control systems, and anyone involved in discrete-time system analysis using MATLAB.

YoshiMoshi
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Homework Statement



A scalar is given by

upload_2018-3-3_20-42-37.png


It is controlled by

upload_2018-3-3_20-43-2.png


With step time h = 0.2 s

1. Find the discrete equivalent model
2. Check the stability of closed loop (K = +1)
3. Obtain the
upload_2018-3-3_20-44-11.png
via the Bode plot

Homework Equations

The Attempt at a Solution



So for question 1. This is where I'm struggling.

I know how to discrete a transfer function in terms of matrix A, B, C, and D through MATLAB easily. However how do I do that for a scalar, where I don't have matrix A, B, C, and D but just single values? Also how does the controller effect this?

I tried searching on google a bit, and can't find a solved example that is similar to this problem.

I know that question 2, I can get once I have the answer to question 1 by easily plotting the Nyquist plot.

I know that question 3, is very easy with MATLAB.

THANKS FOR ANY HELP!
 

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YoshiMoshi said:

Homework Statement



A scalar is given by

View attachment 221400

It is controlled by

View attachment 221401

With step time h = 0.2 s

1. Find the discrete equivalent model
2. Check the stability of closed loop (K = +1)
3. Obtain the View attachment 221402 via the Bode plot

Homework Equations

The Attempt at a Solution



So for question 1. This is where I'm struggling.

I know how to discrete a transfer function in terms of matrix A, B, C, and D through MATLAB easily. However how do I do that for a scalar, where I don't have matrix A, B, C, and D but just single values? Also how does the controller effect this?

I tried searching on google a bit, and can't find a solved example that is similar to this problem.

I know that question 2, I can get once I have the answer to question 1 by easily plotting the Nyquist plot.

I know that question 3, is very easy with MATLAB.

THANKS FOR ANY HELP!

You're overthinking it...
you do have an ABCD matrix.

Your A matrix is a 1x1.
Your B matrix is a 1x1.
Your C matrix is a 1x1.
Your d matrix is a 1x1
 

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