Saturation function in Simulink

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Peppe
Peppe on 14 Jul 2017
Answered: Endrias on 21 Jan 2019
Hi, I would like to implement following block in simulink. How do I do it in Simulink: U = u_d - K/b * sat(σ /θ)
where: sat(σ/θ) = {1 if σ>θ, σ/θ if −θ ≤ σ ≤ θ, −1, σ < −θ}
u_d is input, K and b are constant. If possible even a matlab function would be appritiated.

Answers (2)

Sruthi Geetha
Sruthi Geetha on 17 Jul 2017
In Simulink, you can implement this using If block and If action subsystem block. In the If block you can specify the number of inputs, If, elseif and else conditions. Connect three If action subsystems to each condition and generate the outputs as 1, sigma/theta and -1 for each of the conditions. You can also do this using a simple code in MATLAB Fcn block:
if sigma>theta
out = 1;
elseif (sigma>=-theta)&&(sigma<=theta)
out = sigma/theta;
else
out = -1;
end
  3 Comments
Leigh Boyd
Leigh Boyd on 11 Aug 2017
did you ever get an answer to this? I have a similar problrm
Peppe
Peppe on 27 Aug 2017
I did it manually in a matlab function. not by using any blocks.

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Endrias
Endrias on 21 Jan 2019
Simulink have a nice IF expression block which you can program the sat(.) function without any matlab written code. If anybody interested to see the block code, let me know.

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