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.

A Comparative Analysis between Heuristic and Data-Driven Water Management Control for Precision Agriculture Irrigation

“…However, the drawbacks of implementing these automated solutions reside in the installation and maintenance cost, which most farmers are unwilling to accept if the return on investment is not clearly defined. To illustrate this, just the acquisition cost and the proper installation and maintenance of soil moisture sensors have a high level of complexity [31]: sensors require individual off-line calibration for the specific soil texture to reach a reliable accuracy, then installation must be carefully conducted to avoid soil air gaps to obtain representative readings; also, at least three sensors are required for an irrigation area and it is a good practice to unearth sensors each year for re-calibration. Since soil moisture sensor is, so far, the element on which closed-loop irrigation is based, lowering costs and efforts must be a priority to make sensor-based automated irrigation a feasible option for farmers.…”

“…Over 45 days, data were collected from four different irrigation areas with different crop types, irrigation systems, and soil characteristics, as denoted in Table 2. As depicted in Figure 3, the irrigation areas were monitored with a solar cell-powered data acquisition system that sensed the crop soil moisture level every minute from three volumetric water content sensors (10HS Sensor from Meter Group), solar radiation (PYR Sensor from Meter Group), wind speed (Davis Cup from Meter Group), air temperature and relative humidity (VP-4 Sensor from Meter Group), and water consumption (Flow-Sync from Hunter Industries) through a wireless sensor network as described in [31]. Coefficients values for matrices A and B from Equation ( 5) were experimentally obtained to model the soil moisture dynamics for each evaluated area properly.…”

How much is enough in watering plants? State-of-the-art in irrigation control: Advances, challenges, and opportunities with respect to precision irrigation

“…An emerging field in precision irrigation control is the modeling of irrigation-related parameters using hybrid automata. Here, plant, soil, and atmosphere-related parameters are modeled using finite state-machines, with individual states described using simple linear models, enabling the modeling and control of complex dynamic systems, as described in Lozoya et al (Lozoya et al, 2019) and Jihin et al (Jihin et al, 2019). Future work in this area would involve integration of the generated plant models in precision irrigation control algorithms, with the aim of predicting plant water requirements and adaptively adjusting irrigation scheduling based on plant response.…”

Energy-Efficient Wireless Communication Strategy for Precision Agriculture Irrigation Control

“…The hydrological balance model describes the dynamics of an irrigation system where the soil moisture changes in the root zone were obtained from the sum of water inflows and outflows. If we consider a plain field (no water runoff) in a dry area (no rainfall and no water capillary rise), as stated by [ 37 ], then the system behavior is expressed as where is the applied irrigation, is the reference evapotranspiration, and , , and are constants that, respectively, denote the irrigation efficiency, evapotranspiration coefficient to incorporate crop characteristics, and soil moisture proportionality to estimate deep percolation. In addition, is the time delay required by the water to reach the crop roots, which usually requires several minutes.…”

“…The model proposed by [ 37 ] describes soil, crop, and weather dynamics for a grass irrigation control system, and we enhanced and applied it to a pecan crop field to implement an adaptive sampling rate sleep/wake-up strategy based on self-triggered control to implement an energy-efficient algorithm to communicate the sensor nodes over a WSN.…”