An expert system to control humidity and temperature of a laboratory scale greenhouse

Abstract

The humidity and temperature of a laboratory scale greenhouse are controlled using a rule-based expert system. The measured inside and outside temperatures of the greenhouse are used with a linearized set of relations of the standard psychrometric chart in order to predict the internal and external relative humidities. Then, the measured internal and external temperatures and relative humidities, respectively, are processed based upon the knowledge of an expert operator to actuate the resistor heaters, the ventilators and the humidifier of the greenhouse using on-off control actions until the internal humidity and temperature reach their reference values. In addition, this research enables the experimental validation of a humidity measurement technique based on a regression analysis of the standard psychrometric chart first proposed by Jepson.