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matlabglobalsimulink

How to initialize constants for a Simulink model from a MATLAB script?

I am building a Simulink model with Matlab Function blocks. These function blocks have a lot of constants, for example g=9.8. I want to initialize all of these constants in one go in a Matlab script, so that I don't have to do so in each function block.

Here's what I have tried until now:

  • In the Matlab Function block I have initialized the variables using a Constant block, which is given as a input to the function block. This system works, but there are a lot of constant blocks in the model and it's getting very clustered.

example

  • I have also tried declaring these variables as global variables in the Matlab script. This does not work.

  • Another way that I have tried is so to create a function script for these constants and then load this function script in the Matlab Function block. This does not work.

Is there a way that I can just initialize these values from the Matlab script and the Simulink model reads it from the Matlab script, without me having to use these constant blocks?

%refercode
%matlabscript

Initialization values;
sim('filenmae.slx');
post processing;

%simulink model 

constant blocks(initialization values) -> matlab function block -> output;

%end

What's the best way to solve this problem?

Solution

  • You could have a single struct containing your variables, which can be selectively used in your Matlab Function blocks. This means you can just have a single Constant block and additional function input, intialized from your script.

    This MathWorks article shows how you can convert the struct into a Simulink Bus for use in your model (you can't use the struct in a constant block directly):

    https://blogs.mathworks.com/simulink/2011/12/05/initializing-buses-using-a-matlab-structure/

    Giving you something like this:

    % initialise constants within struct, keeps the workspace tidy too!
vars = struct();
vars.g = 9.8;
vars.lambda = 2;
% Create bus data for the variables struct
varsInfo = Simulink.Bus.createObject(vars);
% Sim the model
sim( 'myModel.slx' );

    With your constant block configured for the bus as described in the linked article:

    bus config

    Then you can access this within your function

    function y = ( y, vars )
    % MATLAB Function block function within myModel.slx
    y = vars.lambda + u * vars.g;