كنترل كامپيوتري شرايط محيطي گلخانه : قسمت اول - طراحي و پياده سازي سيستم

A Computer-Based Control System for Greenhouse Environment: Part I - Design and Implementation of System

The present study is concerned with the design and implementation of a computer-based control and monitoring system for greenhouses. hor conducting the field experiments a model greenhouse with a floor area of 8 m2, (2x4 m) was constructed. It was covered with double inflated 200pm polyethylene films. Performance of the controller under different environmental conditions was evaluated by installing the system in the model greenhouse. Main components of the system are sensors, a microcontroller, a number of actuators, data processing unit, and data acquisition and recording device. The microcontroller receives data on greenhouse environmental conditions from a number ofʹ sensors installed inside as well as outside the greenhouse and transfers the data to and from a PC via RS 232 port. A graphical user interface was also developed to carry out the monitoring tasks. "[he program implements the control algorithms, comparing the received data with set points, sending control signals to the microcontroller so as to change the states in control devices, namely, heaters, fans, misters, etc., in order to attain the desired set points. To evaluate system performance, a set of experiments were carried out during autumn 2003, in the faculty of agriculture, Karaj. The overall performance of the system in controlling greenhouse air temperature was very satisfactory. The time constant to bring the temperature within the set points was about 10 minutes.