326 Pages 87 B/W Illustrations
    by CRC Press

    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.

    Introduction and Problem Statement
    Greenhouse-Crop Cultivation—Benefits and Challenges
    Automatic Control
    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
    State Estimation
    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
    Concluding Remarks

    An Experimental Application: Tomato.
    Tomato Model
    Greenhouse Climate Model
    State–Space Form of the Complete Greenhouse-Crop Model
    Calibration and Model Results
    Open-Loop Optimization
    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
    System Description
    The Solar Greenhouse Model
    Model of Crop Biophysics
    Sensitivity Analysis, Calibration, and Validation
    Optimal Control

    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


    Gerrit van Straten, Gerard van Willigenburg, Eldert van Henten, Rachel van Ooteghem