An Auto-Tuning PI Control System for an Open-Circuit Low-Speed Wind Tunnel Designed for Greenhouse Technology.
Wind tunnels are a key experimental tool for the analysis of airflow parameters in many fields of application. Despite their great potential impact on agricultural research, few contributions have dealt with the development of automatic control systems for wind tunnels in the field of greenhouse technology. The objective of this paper is to present an automatic control system that provides precision and speed of measurement, as well as efficient data processing in low-speed wind tunnel experiments for greenhouse engineering applications. The system is based on an algorithm that identifies the system model and calculates the optimum PI controller. The validation of the system was performed on a cellulose evaporative cooling pad and on insect-proof screens to assess its response to perturbations. The control system provided an accuracy of <0.06 m·s(-1) for airflow speed and <0.50 Pa for pressure drop, thus permitting the reproducibility and standardization of the tests. The proposed control system also incorporates a fully-integrated software unit that manages the tests in terms of airflow speed and pressure drop set points.
Research Centre BITAL, University of Almería, Ctra. Sacramento s/n, 04120 Almería, Spain. ker154@inlumine.ual.es.
Karlos
K
Espinoza
Research Centre BITAL, University of Almería, Ctra. Sacramento s/n, 04120 Almería, Spain. dvalera@ual.es.
Diego L
DL
Valera
Research Centre BITAL, University of Almería, Ctra. Sacramento s/n, 04120 Almería, Spain. jtorres@ual.es.
José A
JA
Torres
Research Centre BITAL, University of Almería, Ctra. Sacramento s/n, 04120 Almería, Spain. alexlopez@ual.es.
Alejandro
A
López
Research Centre BITAL, University of Almería, Ctra. Sacramento s/n, 04120 Almería, Spain. fmolina@ual.es.
Francisco D
FD
Molina-Aiz
auto-tuning PI controller; greenhouse agriculture technology; low-speed wind tunnel