Development of an educational tool for control engineering

Abstract

On this work, a device was made in order to help the visualization by the student of a PID temperature control and thus fix the concepts learned in the classroom. This device was built primarily with a PIC18F4550 microcontroller, a mini cooler from a PC, a heat resistor, LM35 temperature sensors, liquid crystal display, USB connector, transistors, LEDs, potentiometers, resistors and capacitors. The USB connection is responsible for recording the microcontroller firmware (bootloader mode), for interfacing with a supervisory software, and to supply the system. The heat resistor provides heat to the system. On the other hand, the cooler has the function of removing heat from the system. The liquid crystal display helps the student to check the temperature, the constants of the controller (Kp, Ki and Kd) and the set point temperature or the cooler voltage. The potentiometers provide the option to run the system in open loop, that is, they serve to make the control of the heat supplied by the heat resistor and the cooler voltage manually. Both the heat resistor and the cooler are controlled via transistors switched by PWMs (Pulse Wide Modulation). A computer program was developed in C Sharp language to display the temperature over time measured by the sensors. The program also is used to adjust the constants Kp, Ki and Kd of the controller and the temperature set point. The microcontroller firmware allows the system to operate in both open and closed loop modes. This work allows the student to learn in practice the control actions when the controller parameters are changed, contributing to improve the acknowledgment of Control Engineering.