How can I tune a block parameter till I retrieve a desired output?

I would like to be able to run a simulation which tunes the gain value 'A' (The amplitude of my sine wave) so that for a given maximum amplitude of {\theta}, the simulation runs till it finds an appopriate gain 'A' value.

For example: If I would like my {\theta} amplitude to be no more than 2, then for all other values which my {\theta} maximum amplitude does not reach or surpass 2, tune 'A' for values which my {\theta} would achieve a maximum amplitude of 2.

I have tried:

a) Work with If / Else. But this does not allow subsystems with multiple actions.

b) Try using the Logic function 'Compare'. But did not find a proper way to tune 'A'

c) I tried adding a PID, rather than using 'A' as a gain, I would use P as my 'A' value. But did not try further with the I nor D controller for tuning the signal.

d) I tried reworking the whole system. Rather than start integrating from \ddot{\theta}, I started to differentiate from {\theta} (as then I would define my {\theta} as an input rather than a fixed ouput). Never tried this one before, therefore my system would give strange results.

Answer 1

[sruthi gundeti]

Define Gain 'A' Value From Workspace and Output Variable as To workspace variable and use Data Inspector to record each simulation output

By using m- script

In a for loop

1. change the value Gain A

2. Run the simulation

3.When the Output variable satisfies the criteria ,Break the loop

4.Going over large number of simulations can collapse matlab so limit the iterations of Gain A values and check the results manually to decide the appopriate gain 'A' value.

[arturo pietri]

Thank you for your reply.

I gotta check on my side now. I got a little bit stuck with the m- script and the For loop. Because when I used the From Workspace block in simulink, it would run in a double variable (time series).

So I am here still learning how to write the m- script, the for loop.

[arturo pietri]

Hello!

I tried following your suggestion. This is what I did:

1) Defined my Gain A value as a variable From Workspace block.

2) Defined my output (phi) as a variable To Workspace block.

3) Created a for loop m-script which looks as the follow:

for i = 0.001:0.0025:0.1
   A = [0 i];
   %Load model
   load_system('Model1');
   %Simulate Model
   sim('Model1');  
   % Open the Simulation Data Inspector
   Simulink.sdi.view;
   % retrieve phi values from output Simulation
   phi = ans.get('phi') 
   if phi == 2
       break
   end
end

Thank you again for your suggestion!!

Only detail that I am missing is the break condition (to stop simulation when phi == 2). Which is not working.

I am not sure if I am retrieving correctly the To Workspace variable (phi) by: phi = ans.get('phi') , or if my If statement is quite vague. Do I create a new post and accept your answer?