Monitoramento e controle de temperatura de uma estufa utilizando o conceito de sensor virtual.

Abstract

Quantities and physical phenomena, such as pressure, volume, potential difference, the phenomenon of boiling, electric current and resistance, among others, depend on temperature, which makes it a parameter of great relevance. It is one of the variables most used in different segments of the process control industry. Automatic control of process has performed a fundamental role in the advancement of engineering and science, and is very important and integral part of the industrial and production process. Currently, soft sensors have been used by industries to make with which physical system meets performance specifications previously established successfully. Thus, in this work, the system in question is a thermal conservatory, which uses the concept of soft sensors to perform the monitoring and control of temperature of this thermal conservatory, based on two aspects: Measurements, where several repetitions of tests were performed to obtain a relationship of the voltage that is applied in the resistance to warm the interior of the thermal conservatory and the temperature measured by the sensor, having thus a reference of which temperature value expected according to the applied voltage and with the variation of the time information of this value of the voltage applied; and Modeling and Control, where is presented the evaluation of SIMC (Skogestad - Internal Model Control) and CHR (Chien, Hrones and Reswick) methods as a control strategy for dynamic model obtained of the plant in study, in this case, first and second order systems with delay. The acquisition of temperature values is performed by the data acquisition board, and the implementation of the routine for the calculation of the controllers and the graphical interface are performed in the MATLAB software.