MEASUREMENT AND CONTROL OF TEMPERATURE

Since the Technology Institute of Toluca is a public university, we (the students) are needed to do a social service. There are several ways to do this. A group of four electronics (Alejandro, Abelardo, Diego and me) engineering students, decided to seek a project to apply our knowledge.

We landed a project in the Chemistry Laboratory of our institute where they needed to measure the temperature of both dryers (lineal and rotatory respectively) and to control the temperature of the rotatory dryer.

We split our group in two teams, Abelardo and Diego, worked out the software part, meanwhile Alejandro and me worked out the hardware part of the system.

The system we implemented have the following parts:

1. Control and UI aka. "The brain": Arduino Nano, LCD 20x4 and Rotatory Encoder.

2. Power (only for the rotatory dryer): Relay.

3. Adquisition components: Thermocouples J-type*, MAX6675 and Arduino Nano.

* The thermocouples are, basically, temperature sensors.

A simple explanation for the system used in the rotatory dryer is:

We measure the temperature with the thermocouples, this sensors gives us an analog signal that we convert to digital signal through the MAX6675 module. We need to do this in order to be able to read this data with the arduino nano. 

In this point, we already have the value of the temperature in Celsius degrees. The next step is to control the temperature.

Given a certain input value (established by the user), we are going to activate our actuator, a heating resistance, to heat up the system until we reach the established input value (or setpoint). When the system reach our setpoint the heating resistance will be turn off.

In this case, we didn't employ a PID controller because an ON/OFF controller is easier to implement and is completely capable of controlling a resistive load.