A Precision Irrigation Model Using Hybrid Automata

Abstract

HighlightsControl theory applied to precision irrigation reduces water consumption and improves crop productivity.A model-based control using hybrid automata is proposed to describe soil, crop, and weather dynamics.The model was developed and validated with experimental data from a grass irrigation process.The proposed model can be used to develop robust and real-time control algorithms to improve irrigation systems. Abstract. Closed-loop control for precision irrigation represents an effective method to provide water savings in this resource-intensive activity. Typically, implementation of these systems uses an on-off control approach with soil moisture as the feedback variable. In these cases, no process modeling is required due to the simplicity of the implemented control algorithm. However, the amount of water consumed by irrigation globally presents an interesting application area for the control discipline. Therefore, to obtain greater water savings and to improve crop productivity through control theory, an irrigation model is required that integrates the three main elements in the irrigation process: soil, crop, and weather. This article proposes a hybrid automata model for a closed-loop irrigation system applied to a grass-covered area. The main measured variables used to represent the process dynamics are soil moisture, vegetation index, and evapotranspiration. The hybrid automata approach allows a complex system to be modeled as a finite state machine in which there is a specific linear model for each state. When certain conditions are met, the system transitions from one state to another, and the new behavior is represented by a different linear model. To develop the proposed model, experimental data were obtained from an irrigation process, the data were analyzed to produce a model using the hybrid automata approach, and finally the model was validated with a new set of measured data. Keywords: Closed-loop irrigation, Evapotranspiration, Hybrid automata, NDVI, Precision irrigation modeling.