to validate transfer function

i got transfer function from excel now i need to ensure that i got correct transfer function by giving some value as input

(25.03 / s + 0.4309 ) . this is the transfer function that will give square of input. but when i tried in simulink it is showing different value

[Sam Chak]

@Chennam: ... the transfer function that will give square of input.

Hi, regarding the transfer function you mentioned that "will give square of input," the term "give" implies that the transfer function produces a specific output response. However, you described this output response as the "Square of Input," which is a bit perplexing. Could you please provide further clarification by presenting a figure or sketch illustrating the expected output?

Additionally, according to mathematical conventions, the syntax "25.03 / s + 0.4309" is interpreted as . Is this the intended interpretation in your case? If not, please use "brackets ()" to indicate the precedence level in which MATLAB should evaluates the transfer function.

[Chennam]

Hey there, i have Excel data which contains my input and output values of sensor. By using system identification i estimated transfer function as "25/(s+0.4309)" now when I used this transfer function in simulink model and gave look up table data as input to the transfer function I am not getting corresponding output value for input, instead I am getting different value.

[Sam Chak]

Hi @Chennam,

Can you copy/paste the code (click the indentation icon )? Also attach the input data.

[Chennam]

this is my simulink transfer function( which will be estimated from excel containing numbers and theirs squared values ) .i estimated it by tfest but when tried in simulink 
if i give 2 as input to this transfer function it has to give 4 as output but its giving other than 4 

data = iddata(sq,i,0.1)
sys = tfest(data,1,0)

compare(data,sys)
sys

when i run the above script i got tranfer function.

[Chennam]

@Sam Chak this is my problem

[Sam Chak]

Hi @Chennam Below is the transfer function that has been created. It is designed to generate an output response based on an input signal. What would be the next MATLAB code to be inputted into the transfer function?

s   = tf('s');
G   = 25.03/(s + 0.4309)

G =
 
    25.03
  ----------
  s + 0.4309
 
Continuous-time transfer function.

Answer 1

[nick]

Hi Chennam,

I understand that you are attempting to determine why Simulink is not displaying the corresponding output value of the sensor. You are inputting the sensor's data into the estimated transfer function, which was obtained with the assistance of the System Identification Toolbox.

As you mentioned, the sensor outputs the square of the input data, which can be described by the following equation: :

This system is non linear and transfer function is defined only for LTI systems. Therefore, the estimated transfer function will contain some inherent errors and will not exactly replicate the values.

You may refer the "Fit" report field in the Report property of the model to know about the "FitPercent" and "MSE". You may refer the documentation to know more about "tfest" :

https://www.mathworks.com/help/ident/ref/tfest.html

Hope this helps.