microclimate variables such as temperature and relative humidity (RH) are highly
nonlinear and strongly coupled, and the greenhouse is largely perturbed by the
outside weather. Also the aforementioned objectives (yield, quality, low cost)
presents conflict of interest because generally, high control precision agriculture
requires extra energy consumption (Haigen et al. 2010).
13.11.1 The Last Decade
Despite many technological limitations, greenhouse engineering developments
during 1990s shows significant progress in different fields. There have been significant advances in the modeling of thermal behavior of the greenhouse and much
effort was directed toward understanding ventilation. Analysis has shown that
different sources exist (thermal and wind induced forces) and these have been
analyzed. The existence of internal circulating air patterns has also been established. Considerable progress has been made in developing methods to provide
CO 2 setpoint trajectories that maximize the margin between the financial benefit of
enrichment and the cost of the CO 2 used (Critten and Bailey 2002).
Notwithstanding the impressive progress in control theory and the understanding about phenomena related with the greenhouse microclimate, conventional
control techniques were almost exclusively used during last decade. Although
reached solutions were barely reliable, attempts to use modern techniques to
improve the quality of the control was limited by the high complexity of these
techniques and the low computational power available, making its application on
current hardware impossible (Sigrimis and King 2000).
13.11.2 Greenhouse
Different research has been conducted regarding climate control for protected
agriculture applications. The main objective of these investigations is to find an
accurate model that represents the greenhouse environmental dynamics and an
efficient and a flexible controller that adjusts the microclimate variables of interest.
This problem has been the focus of many re-searchers worldwide who have
analyzed, experimented, and proposed many climate control systems in order to
manipulate variables such as temperature, RH, CO 2 enrichment, radiation, and
many others that are necessary to generate the fundamental conditions for successful protected agriculture (Van Straten et al. 2000).
The greenhouse-crop system can be considered as a solar collector involving
sensible and latent heat exchanges. It is a complex system that can be divided into
three main components, which presents a high mutual interaction: internal atmosphere, the crop, and the soil. The behavior of the whole system not only depends
on these interactions, but also on the outside weather and on the actions of
386
M. S. Acosta-Navarrete et al.
nonlinear and strongly coupled, and the greenhouse is largely perturbed by the
outside weather. Also the aforementioned objectives (yield, quality, low cost)
presents conflict of interest because generally, high control precision agriculture
requires extra energy consumption (Haigen et al. 2010).
13.11.1 The Last Decade
Despite many technological limitations, greenhouse engineering developments
during 1990s shows significant progress in different fields. There have been significant advances in the modeling of thermal behavior of the greenhouse and much
effort was directed toward understanding ventilation. Analysis has shown that
different sources exist (thermal and wind induced forces) and these have been
analyzed. The existence of internal circulating air patterns has also been established. Considerable progress has been made in developing methods to provide
CO 2 setpoint trajectories that maximize the margin between the financial benefit of
enrichment and the cost of the CO 2 used (Critten and Bailey 2002).
Notwithstanding the impressive progress in control theory and the understanding about phenomena related with the greenhouse microclimate, conventional
control techniques were almost exclusively used during last decade. Although
reached solutions were barely reliable, attempts to use modern techniques to
improve the quality of the control was limited by the high complexity of these
techniques and the low computational power available, making its application on
current hardware impossible (Sigrimis and King 2000).
13.11.2 Greenhouse
Different research has been conducted regarding climate control for protected
agriculture applications. The main objective of these investigations is to find an
accurate model that represents the greenhouse environmental dynamics and an
efficient and a flexible controller that adjusts the microclimate variables of interest.
This problem has been the focus of many re-searchers worldwide who have
analyzed, experimented, and proposed many climate control systems in order to
manipulate variables such as temperature, RH, CO 2 enrichment, radiation, and
many others that are necessary to generate the fundamental conditions for successful protected agriculture (Van Straten et al. 2000).
The greenhouse-crop system can be considered as a solar collector involving
sensible and latent heat exchanges. It is a complex system that can be divided into
three main components, which presents a high mutual interaction: internal atmosphere, the crop, and the soil. The behavior of the whole system not only depends
on these interactions, but also on the outside weather and on the actions of
386
M. S. Acosta-Navarrete et al.