Crop growth control

Abstract

This chapter addresses the problem of greenhouse crop growth control using a hierarchical control approach. The proposed control scheme consists of two layers. In the lower one, any of the controllers described in Chap. 3 are used. The upper layer calculates optimal climate setpoints based on different criteria. First, a single objective function formulated according to economic criteria is proposed, where optimal temperature setpoints are calculated for the lower layer. Later, a second approach based on multiobjective optimization is developed, where the solution to this problem is to find reference trajectories for diurnal and nocturnal temperatures (climate-related setpoints) and electrical conductivity (fertirrigation-related setpoints). The objectives are to maximize profit, fruit quality, and water-use efficiency, these being currently fostered by international rules. An optimization algorithm is used with a receding horizon strategy to provide the desired climate to the lower layer during the whole campaign. Representative experimental results of the implementation of the hierarchical control architecture are presented and discussed in this chapter.