how can i define specific sample time points?

i want to sample a step in simulink. But i want to define at which point my step is sampled how can i define a vector with the timepoints?

e.g. my simulation runs 1sec.

Then i want to sample the simulation e.g. at [0.01, 0.02, 0.03, 0.05, 0.09, 0.15, 0.3 .... ]

is this possible and how?

edit: is it possible to set the Solver to inherited (-1)

And i put a triggerblock into my simulinkmodel to specify when my model samples? Could this be a solution? If yes how can i realise it?

[David Miller]

Let T be an array of certain time steps you would like to sample. Let your time step be min(abs(b-a)), where b and a are in T. Call this value t, then:

for dt = 0:t:1
  simulation*t;
  if ismember(i,T)
    *sample*
  end
end

[Walter Roberson]

That does not sound like a Simulink based solution ?

[Timo]

mh. I need to know where i can setup the discrete sample values in matlab/simulink.

i can configure the following 2 screens. But i dont know how i can define a vector with all my timings in which my simulink model samples.

[Timo]

Another idea:

is it possible to set the Solver to inherited (-1)

And i put a triggerblock into my simulinkmodel to specify when my model samples? Could this be a solution? If yes how can i realise it?

Answer 1

[Swarooph]

There is a lot of information required to be able to help choose a solver (Does your system have continuous states? Does it have discontinuities like switches etc?). So, I am going to suggest the following to see if this might work:

In the second screen that you are showing (called the Solver pane), set the following properties:

Type: Variable-Step
Solver: auto (if you have that option) or ode45

Now navigate to the Data Import/Export pane (choose on the left side) and set the following properties on the right side:

Output options: Produce specified output only
Output times: Your full time vector e.g. [0.01, 0.02, 0.03, 0.05, 0.09, 0.15, 0.3 .... ]

NOTE: These options mean output is produced ONLY for the specified time vector. Simulink would have no control over the accuracy of your model. IF you want Simulink to assure accuracy within the specified tolerance, set the following property instead:

Output options: Produce additional output
Output times: Your full time vector e.g. [0.01, 0.02, 0.03, 0.05, 0.09, 0.15, 0.3 .... ]

This means, Simulink will control the solver step size as to when the system needs to be solved to get the best response. In addition to this, we can add your time points as well to FORCE the solver to produce additional outputs.

To get more information about this property, refer to the documentation here .

[Timo]

Hello Swarooph,

thanks a lot!

This helped me so much!!!!! Thank you