# Help for a cooling device using Peltier

hello,

Being a beginner, I apologize in advance for the naiveness of my question. I'm developping a cooling device using Peltier modules but the hardware isn't relevant to the question I'm asking.

I have no problem to read, map and export measures of temperature. I'm looking to make the arduino calculate sigmoid function with manually defined parameters:

1/(1+ exp((t- inflexion)/slope))

Schematics of the expected effect

The idea is to make arduino compare the analog value measured and the "theoretical" value and adapt the analog command it is sending in order to lessen the difference between these two values.

I've looked into PID controller but weren't able to find a simple arduino project that could shed some light on how to implement it.

Any idead are very welcomed, I'll take any help I can get.

Antoine

Cartonique: The idea is to make arduino compare the analog value measured and the "theoretical" value and adapt the analog command it is sending in order to lessen the difference between these two values.

So your using quoted theoretical values, are these from the data sheet of the junctions you have?

How are you planning on getting a “analog” command from the Arduino?

Quoted from the Arduino reference for the PID library. A PID controller calculates an 'error' value as the difference between a measured [Input] and a desired setpoint. The controller attempts to minimize the error by adjusting [an Output]."

Seems exactly what you need to do, but if you want to further modify it based on the “theoretical” characteristics of your setup then that’s possible too.

The idea is to make arduino compare the analog value measured and the "theoretical" value and adapt the analog command it is sending in order to lessen the difference between these two values.

That is what a PID controller does. Note: a PID controller can drive a process value that varies with time or another parameter. Just have the SETPOINT vary with that parameter.

The analog value representing what is being measured?

What does the analog value "being sent" do?

What is the sigmoid function supposed to represent?

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