How can I use system identification on a Temperature-Time data

Hello,

I am trying to create a grey box using the system identification toolbox on matlab to idenitfy the physical model and transfer function of the process using thermocouples with output temperature and input time. However, my thermocouple (type K) data that I've retrieved from the experiment recorded the temperature increase over 12 minutes (in seconds) of the experiment. So my data is just temperature against time. I have issues with inserting my data in either time domain, as the time plot will plot the input as time-over-time (therefore same value), and for the frequency domain I have no information about the phase/frequency to allow me to insert the data and proceed. How can I continue?

Answer 1

[Himanshu]

Hi Christos,

Follow the steps mentioned below to insert the temperature – time data in the system identification toolbox:

• You could start by transforming the temperature data you have versus time into a suitable input-output format for system identification. One typical method is to consider the temperature to be the output and the step input to be the input signal. You can make a step input vector with the same length as a time vector that represents the time points of your temperature observations.

• Then, Use the “iddata” function to create an “iddata” object that represents your input-output data. Follow it up by plotting the temperature data against time using the plot function to ensure it is correctly represented.

Use the following link to refer to the System Identification Toolbox’s documentation - https://in.mathworks.com/help/ident/

Hope this helps!