Greenhouse control system manufacturers produce equipment and software with hundreds of settings and, while they hold training courses on how to adjust these settings, there is as yet no integrated instruction on when or why. Despite rapid growth in the greenhouse industry, growers are still faced with a multitude of variables and no unifying framework from which to choose the best option.
Consolidating 30 years of research in greenhouse climate control, Optimal Control of Greenhouse Cultivation utilizes mathmatical models to incorporate the wealth of scientific knowledge into a feasible optimal control methodology for greenhouse crop cultivation. Discussing several different paradigms on greenhouse climate control, it integrates the current research into physical modeling of the greenhouse climate in response to heating, ventilation, and other control variables with the biological modeling of variables such as plant evapo-transpiration and growth.
Key topics include state-space greenhouse and crop modeling needed for the design of integrated optimal controllers that exploit rather than mitigate outside weather conditions, especially sunlight, given widely different time scales. The book reviews classical rule-based and multivariable feedback controllers in comparison with the optimal hierarchical control paradigm. It considers real and hypothetical examples including lettuce, tomato, and solar greenhouses and examines experimental results of greenhouse climate control using optimal control software. The book concludes with a discussion of open issues as well as future perspectives and challenges.
Providing a tool to automatically determine the most economical controls and settings for their operation, this much-needed book relieves growers of unnecessary control tasks, and allows them to achieve the best possible trade-off between short term savings and optimal harvest yield.
Table of Contents
Introduction and Problem Statement
Greenhouse-Crop Cultivation—Benefits and Challenges
Elementary Description of the Greenhouse-Crop System
Measurements and Instrumentation
Decomposition, Fluxes, and Information Flows
General State–Space Representation
Hierarchical Computerized Control
Current Status of Computerized Control
How Is This Book Organized?.
Introduction to Optimal Control of Greenhouse Climate
Introduction and Motivation
A Simple Illustrative Example
General Formulation of Optimal Control Problems
Benefits and Difficulties Associated with Optimal Control
Open-Loop Optimal Control
Optimal Control Theory
Optimal Control Algorithms
Closed-Loop Optimal Control
Linear Quadratic Feedback Control
Greenhouse Cultivation Control Paradigms
Optimal Control Revisited
Earlier Surveys of Greenhouse Climate Control Solutions
Classification of Proposed Greenhouse Climate Control Solutions
Discussion and Conclusion
A Seminal Case: Lettuce
The Optimal Control Problem
Optimal Control Case Studies
An Experimental Application: Tomato.
Greenhouse Climate Model
State–Space Form of the Complete Greenhouse-Crop Model
Calibration and Model Results
Two–Time-Scale Receding Horizon Controller (RHOC)
Evaluation of Optimal Control
Assessment of Economic Result as Compared with Conventional Control
Discussion and Conclusions
An Advanced Application: The Solar Greenhouse.
Description of the Solar Greenhouse Concept
The Solar Greenhouse Model
Model of Crop Biophysics
Sensitivity Analysis, Calibration, and Validation
Developments, Open Issues, and Perspectives
Developments in the Greenhouse Industry and Consequences for Control
Prerequisites for Future Control Systems
Challenges for Science and Technology
Showstoppers for Optimal Control
Conclusions and Perspectives