Simulink build a loop and define intial conditions

I want to build a loop in simulink with some intital conditions, and then for the next time step use the outputs as the inputs. How do I do this?

Answer 1

[Jon]

In general you should be able to run your simulation iteratively by starting the simulation programatically using the MATLAB sim function (if you're not already familiar with the sim function, type doc sim on your command line to read the documentation)

So you would make a loop, something like this

for k = 1:numIterations
    simout = sim('myModel',...)
    % now do something with the output variables ...
    % for example assign base workspace variable that are used as inputs in
    % next loop
    a = simout....
    b = simout. ...

end

You may want to look at the documentation for the fast restart option, to avoid compiling the Simulink model with each iteration https://www.mathworks.com/help/simulink/ug/fast-restart-workflow.html

Exactly how you assign the outputs to the inputs depends upon what kind of values you are changing. However if they are values of constant blocks or mask parameter values that are assigned to base workspace variables it is as simple as reassigning these base workspace values (as I indicated in the example above)

[Jon]

Another idea would be to just run one long simulation and periodically feedback the outputs to the inputs within the simulation itself. So to do this you could use, for example, a unit delay block (from the discrete blocks in the Simulink library browser) with a long sampling time. The output(s) of your model would connect to the input of the unit delay block(s). The output of the unit delay blocks would connect to the input of your model. You would set the initial condition for the unit delay to get things started.

[Jon]

Were you able to get this running?