How would I set up a my Simulink systems to examine step and bode response?

Hi everyone,

I am sorry to bother you all, attached is a zip folder of some simulink models. I wish to analyse the system response such as step, impulse Bode e.t.c. However, I am not sure how to linearise the system so that I can analyse the system outputs.

Any help would be appreciated as looking through MATLAB documentation was not very helpful. In the zip there are 5 systems. systems 3 and 4 are almost identical. Sys 1 is the basic system, sys 2 has feedback, sys 3 is a feed forward system, sys 4 is the same as sys 3 (it has a longer delay) and sys 5 is a combination of sys 2 and sys 3.

Thank-you all for your time and support.

Answer 1

[Altaïr]

Hey @Kez,

The Model Linearizer app allows for linear analysis of nonlinear Simulink models. Using the app one can perform the following actions among several others:

• Interactively linearize models at different operating points.
• Perform frequency response estimation of nonlinear models.

The example below gives the workflow of linearizing a model using the Model Linearizer

https://www.mathworks.com/help/releases/R2022b/slcontrol/ug/linearize-simulink-model.html

In the above example, a Water-Tank system is linearized using the Model Linearizer app, and Bode plot is generated for the linearized system. A command line approach to perform the same actions is also demonstrated later in the example.

Here is a procedure I followed to linearize the ‘P1_SB_Open_Loop.slx’ model similar to the above example.

1. Firstly, I added 3 analysis points: 2 'Input Perturbations’ and one ‘Output Measurement’ as shown below.

2. I opened the Model Linearizer from the Apps tab and clicked on the Bode option under the Linearize section. Here is the plot I obtained.

The linearized system is visible under the Linear Analysis Workspace tab on the left pane, which can later be copied to the base workspace.

Kindly refer to the below documentation of Model Linearizer for more details:

https://www.mathworks.com/help/releases/R2022b/slcontrol/ug/modellinearizer-app.html