WO2021240231A1

WO2021240231A1 - Method and automatic watering control system to determine the amount of water to be released to a crop based on spectral analysis of greenery

Info

Publication number: WO2021240231A1
Application number: PCT/IB2020/060560
Authority: WO
Inventors: Carmelo BATTIATO; Rinaldo RENI; Nicola Nescatelli; Riccardo BENINI; Federico DI VINCENZO; Andrea Procaccini
Original assignee: Ecobubble S.R.L. Startup Costituita Ai Sensi Dell'art. 4 Comma 10 Bis D.L. 3/2015 Conv. Con Legge 33/2015; Nebula7
Priority date: 2020-05-26
Filing date: 2020-11-10
Publication date: 2021-12-02

Abstract

Method of watering control consisting in the iterative application of phases and steps that modify - increase or decrease - the quantity of water depending on the weather variables and on the spectral analysis of the reflectance of the plants until reaching the dose corresponding to the maximum level of luxuriance of the crop, implemented by a system consisting of a set of independent and cooperating computerized units - devices, sensors and actuators - which processes the data and which at set deadlines delivers the quantity of water that is determined by the application of the method, so as to avoid wasting water.

Description

Title of Invention: METHOD AND AUTOMATIC WATERING CONTROL SYSTEM TO DETERMINE THE AMOUNT OF WATER TO BE RELEASED TO A CROP BASED ON SPECTRAL ANALYSIS OF GREENERY Technical Field

[0001] The invention may be classified amongst the systems for the control of watering and in particular systems for controlling the water balance and systems which use meteo rological data and the internet of things for controlling watering. On the bass of the IPC classification reference is made to code A01G 25/16 (A01G horticulture; cul tivation of vegetables, flowers, rice, fruit, vines, hops or seaweed; forestry; watering - 25/16 control of watering).

Background Art

[0002] The management and control systems for watering crops, both domestic or extensive, in greenhouses or outdoors, are currently characterised by the possibility of receiving and processing data to improve the watering regimes according to specific objectives. The water requirement is determined by means of data gathered in different ways, including visual inspection, soil moisture sensors, evaporation measurements or cal culating the evapotranspiration once the values of the weather variables are known and, lastly, satellite detection means.

[0003] There are therefore methods which link the quantity of water dispensed to values of physical parameters, the first of these being the measurement of the soil moisture content, and, on the basis of this value, deciding whether and how much to deliver or integrate the flow during particularly dry periods. Some parties have developed a system in which the data received from the sensor in the field is analysed and compared with the physiological data for the plant deduced from a proprietary database with the aim of defining in this way the water required by the plants.

[0004] There are also methods which determine the quantity of water to be dispensed on the basis of the forecast and/or actual rainfall. In other cases, especially in the agricultural or flower growing sectors, the systems are based on the reintegration of the quantity of water consumed by a crop by evapotranspiration, which can be determined by means of one of the formulae known in the literature, for example the Penman-Monteith equation (CN106702981B, CN201310129812, CN201910666927).

[0005] A method is known for generating a watering plan which reduces the water con sumption requirements for the vegetation (US2020037520) on the basis of the estimated depth of the roots of the irrigated vegetation and determines a permitted water consumption threshold for the vegetation based on the depth of the root itself.

[0006] There are methods which take into consideration the colour and the “vigour" of the plants to determine the goodness of the nutrients which are supplied to the crop (US2017367346) in which the quality of the plants is judged by visual inspection.

[0007] The methods mentioned above are inherently static and do not allow an accurate im provement of the efficiency of the response of the crop in which the overall per formance is also determined by many additional parameters and variables including geometry, type and depth of soil, initial conditions and the hyetograph of the rain which could fall or has a fallen, which in any case are components that are not linked to the way of managing the water flows of irrigation systems.

[0008] Industrial uses of the spectral analysis carried out from reflectance “images” of a crop currently comprise the surveillance of large cultivated areas in order to measure a certain spectral index. For example, the NDVI index is used to distinguish “naked” soil from grass or forest, identifying plants under stress and recognising different types of crops or different phases of the development of the same crop. Although the spectral analysis, mediated by the calculation of various indicators studied in the literature, has been used for some time to study the vigour of crops, it has never been used in the context of the automated regulation of the flow of irrigation water for a crop.

[0009] No automatic method is known which links the water supply to a crop to its actual water requirements, determined on the basis of the reference evapotranspiration corrected dynamically through an index which measures the vigour of the crop itself, therefore directly for the final aim of the water supply, having both the characteristics of the garden in which the crop is located and the continuous variations in the weather conditions considered in the calculation of the reference evapotranspiration.

[0010] In terms of the architectural profile, some systems remotely process the calculation of the irrigation flow on the basis of the measurement of the moisture content of the soil, the wind, the solar radiation or which integrate the flow in periods of particular dry conditions (US 12/432,632). Other systems have been developed based on cloud computing and allow dispensing of water on the basis of forecast and/or actual rainfall by processing of data processed on network processors (CN201610067996.7A).

[0011] However, the latter operate as standalone systems without entering data and resources in common to create a territorial network dedicated to providing an extended representation of the vigour of the crops.

[0012] The configuration of a crop P is a set of parameters which characterise a prede termined garden or green area. Said parameters include, amongst other things:

[0013] - geographical position and height of the garden,

[0014] - characteristics of the soil (chemical composition, filtration capacity, variation of the water content of the layer of soil affected by the balance).

[0015] The reference evapotranspiration ETO is the quantity of water which per unit of time passes from the soil into the air in the vapour state due to the combined effect of the transpiration of the plants and the evaporation directly from the soil. ETO is a positive rational number expressed in mm.

[0016] ETO can be determined by one of the formulas known in the literature (for example, the Penman-Monteith equation) and the knowledge of the average value per unit of time of the weather variables, including: temperature and relative humidity; relative sunshine duration; wind speed and direction; solar radiation; relative atmospheric humidity.

[0017] ET is the quantity of water dispensed to the crop per unit of time, determined according to the method of the invention. ET is a positive rational number expressed in mm.

[0018] The crop correction coefficient K is defined as the ratio between the reference evapo transpiration ETO and the quantity of water ET to be dispensed, that is K = ET / ETO. Initially, this is the value considered optimum for the health of plants in a garden char acterised by the predetermined parameters, as obtained from the literature, from the practice and/or from the results of tests carried out in the laboratory and/or in a greenhouse. The method of the invention introduces corrections to the initial value of K according to the degree of vigour measured. K may be increased or reduced, multiplied by D1 > 1 and D2 < 1. K, D1 and D2 are rational numbers.

[0019] The degree of vigour RG of a crop is a value representing the state of vigour of the plants determined by the study of the spectral emissions of the leaves. The hyper spectral data makes it possible to study the vegetative physical-chemical processes, allowing certain indicators to be developed representing the degree of vigour, such as, for example, NDVI - Normalized Difference Vegetation Index. This provides in formation on the state of health of the vegetation, any excess or lack of water, the nu tritional state of the fruits and the productivity of the crops. RG is a rational number within the range [RGmin - RGmax].

[0020] T is the unit of time defined inside the system, that is, the time interval between one application of the steps of the method and the next application. T is a whole number expressed in minutes.

[0021] The method and the system

[0022] The method refers to a homogeneous group of plants but may be applied to a generic crop, having different characteristics. Similarly, it relates to a crop with predetermined parameters but may be applied to a generic crop, either extensive or domestic, either outdoors or in greenhouses, with different parameters.

[0023] The method according to the invention operates to improve the vigour of the crop by applying periodic variations to the value of the correction coefficient K initially adopted for the reference evapotranspiration ETO.

[0024] Assuming initially that a defect in the vigour of the crop is due to lack of water, the quantity of water dispensed ET = K * ETO is progressively increased by positively updating by D1 the correction coefficient in order to improve it and reach the maximum value RGmax.

[0025] If, however, after an interval of time after dispensing, the degree of vigour does not improve the correction coefficient K it is progressively reduced to improve it and reach the maximum value RGmax.

[0026] The method described may be implemented by a system comprising a set of in dependent and communicating components as illustrated in the principle diagram of FIGURE 2 which is able to actuate the periodic and iterative execution of the phases and steps as shown in the flow graph of FIGURE 1.

[0027] The system consists at least of the following components.

[0028] (1) a computerised implementation device which is able to implement logics for monitoring, command and control for the crop equipped with an interface with a local or remote operator and a communication line on a proprietary and/or public network via cable or via radio (la) to communicate with external units and/or sector control units with which to share data and resources.

[0029] (2) a zone reference evapotranspiration sensor, connected to the device (1). The sensor operates on the basis of weather data. The sensor provides the value ETO of the quantity of water which per unit of time passes from the soil into the air in the vapour state due to the combined effect of the transpiration, through the plants, and the evaporation, directly from the soil.

[0030] (2a) a communication line between the implementation device (1) and the evapotran spiration sensor (2). The connection may be via cable or via radio

[0031] (3) a vigour sensor of the crop which provides the current value of the degree of vigour RG representing the state of vigour of the plants obtained by analysing the spectral emissions of the leaves of the crop

[0032] (3a) a communication line between the implementation device (1) and the vigour sensor (3). The connection may be via cable or via radio

[0033] (4) an actuator for controlled dispensing of water applied to the hose (5) on which the water release nozzles act in a uniform manner

[0034] 4a) a communication line between the implementation device (1) and the dispensing actuator (4). The connection may be via cable or via radio. As illustrated in the flow graph of FIGURE 1, the method according to the invention consists in iterative ap plication of at least the phases listed below, each phase consisting at least of the steps indicated inside it. [0035] Phase [A] setting the initial data (steps a. - d.)

[0036] a. START - an operator sets in the device (1) the crop correction coefficient K, as the value considered optimum for the health of the plants in a predetermined garden char acterised by the parameters P as obtained from the literature, from the practice and/or from the results of tests performed in the laboratory and/or in a greenhouse and the values of A1 and D2

[0037] b. an operator sets in the device (1) the value of the unit of time T as the time interval which expresses the periodic intervals of the dispensing operations

[0038] c. an operator sets in the device (1) the maximum value RGmax of the degree of vigour of the crop

[0039] d. the device (1) acquires from the evapotranspiration sensor (2) the current value of the reference evapotranspiration ET0 deduced from the bulletin of a sector agency or by acquiring weather variables and the relative calculation with a known formula.

[0040] Phase [B] of steady-state dispensing (steps e. - h.)

[0041] e. the device (1) dispenses a quantity of water equal to ET = K * ET0 actuating the dispensing actuator (4)

[0042] f. the device (1) waits for a time T

[0043] g. the device (1) acquires from the vigour sensor (3) the current value of the degree of vigour of the crop RG

[0044] h. the device (1) compares the current value of the degree of vigour RG with the maximum value RGmax. If the degree of vigour RG is equal to the maximum degree RGmax it continues from point e., otherwise it continues from point i.

[0045] Phase [C] for increasing the correction coefficient (steps i. - n.)

[0046] i. the device (1) increases the crop correction coefficient K by a multiplication factor A1 > 1

[0047] j. the device (1) acquires from the evapotranspiration sensor (2) the current value of the reference evapotranspiration ET0 deduced from the bulletin of a sector agency or by acquiring weather variables and the relative calculation with a known formula

[0048] k. the device (1) dispenses a quantity of water equal to ET = K * ET0 actuating the dispensing actuator (4)

[0049] 1. the device (1) waits for a time T

[0050] m. the device (1) acquires from the vigour sensor (3) the current value of the degree of vigour of the crop RG

[0051] n. the device (1) checks whether the current value of the degree of vigour is greater than the previous value, that is to say, whether it has approached RGmax or is equal to RGmax

[0052] If the degree of vigour has approached RGmax it continues from point i., if the degree of vigour is equal to RGmax it continues from point e., otherwise it continues from point o.

[0053] Phase [D] for reducing the correction coefficient (steps o. - 1.)

[0054] o. the device (1) reduces the crop correction coefficient K by a multiplication factor D2 < 1

[0055] p. the device (1) acquires from the evapotranspiration sensor (2) the current value of the reference evapotranspiration ET0 deduced from the bulletin of a sector agency or by acquiring weather variables and the relative calculation with a known formula

[0056] q. the device (1) dispenses a quantity of water equal to ET = K * ET0 actuating the dispensing actuator (4)

[0057] r. the device (1) waits for a time T

[0058] s. the device (1) acquires from the vigour sensor (3) the current value of the degree of vigour of the crop RG

[0059] t. the device (1) checks whether the current value of the degree of vigour is greater than the previous value, that is to say, whether it has approached RGmax or is equal to RGmax

[0060] If the degree of vigour has approached RGmax it continues from point o., if the degree of vigour is equal to RGmax it continues from point e., otherwise the operator is notified - END.

[0061] The correction coefficient K can be increased / decreased by the number of steps n inside an iterative phase with the application of constant multiplication factors, D1 > 1 and D2 < 1, or by multiplication factors which are in turn increased / decreased with n.

[0062] The unit of time T may be the solar day or a fraction or a multiple of it. The unit of time T may be a constant value or a variable value; in that case, the quantities involved in the method are measured in proportion.

[0063] The parameters of the crop P and the degree of vigour RG may be represented with any level of definition and be treated as discrete variables or be identified with continuous variables.

[0064] The method may be implemented completely or partly through a program housed in a local device or in one or more network apparatuses. 11

[0065] The implementation device (1) may correspond to a specific physical unit or be rep resented by a logic request dedicated to a crop inside a larger device for managing several crops.

[0066] The zone evapotranspiration sensor (2) may consist of a local component which acquires the weather data from the network or a remote component connected to the Internet and which deduces the values of ET0 from external apparatuses.

[0067] The value of the reference evapotranspiration ET0 can be determined from the

Penman-Monteith equation or from another equation recognised in the scientific field, already known or not yet published, and the degree of vigour RG can be determined by the analysis of the reflectance from an NDVI type index or from another formula from the literature already known or not yet published.

[0068] The vigour sensor (3) can be provided with a single element for measuring the re flectance of the leaves or it may have several elements for measuring the reflectance of the leaves whose data is mediated in order to obtain the degree of vigour of the crop RG.

[0069] The values of reflectance of the leaves of the crop can be acquired from dedicated sensors, from local sensors or from remote sensors, for example satellite sensors. Moreover, they can be detected by a proprietary system and by third party apparatuses.

[0070] The dispensing actuator (4) may have the control of a single dispensing valve or it may control a set of dispensing valves which together deliver a quantity of water equal to ET.

[0071 ] Industrial application

[0072] The control system according to the invention is based on a programmable com puterised platform which is able to execute monitoring and control logics. The imple mentation device may consist of one or more units and/or cards based on a PC, mini PC, PLC or other digital electronic device technology which uses a programmable memory to store information or instructions, designed to implement specific functions, aimed at the control of combined and sequential industrial systems for the management of machines and processes.

[0073] The implementation device may be equipped with a local or remote operator interface and be connected via cable or via radio to several sensors and actuators and be connected to a metropolitan network with a territorial management system and to a public network with sector sites. It can be equipped with an operating system of the proprietary or open-source type and be able to execute the control logics defined through a development system and a programming language present in the device itself or through external software.

[0074] The other components of the system are present on the market, such as micro processor sensors and actuators, which allow the connection via cable or via local network and which can have a wide range of sensors, for example for measuring the weather parameters.

[0075] The measurement of the vigour of a crop is generally obtained by remote mea surement and satellite photography, but there are sensors which process indices such as NDVI starting from images of local video cameras which continuously “photograph” the crop. In particular, multi- spectral cameras are available on the market operating both with red light and infrared light (IR) which are easy to use also mounted on a drone as a NDVI solution for assessing plants in agricultural surveys, for analysing and checking the health of the plants, NDVI and yield maps, growth monitoring, identi- fication of crops.

[0076] The actuators are slightly more complex than the measurement sensors since they must also control an active mechanical element such as the solenoid valve. For this purpose , ADC/D AC modules are used which are inexpensive and which at the same time allow a network interface configurable on the basis of the specific requirements.

[0077] Aim and advantages

[0078] The aim of the method/system according to the invention is to provide a complete, measurable and easily replicable solution which, through the monitoring of the degree of vigour of the leaves, specifies the steps to be performed to determine the quantity of water necessary and sufficient to keep a crop in excellent health.

[0079] The aim of the method is also to measure, improve and certify the degree of health of a crop, if necessary by sharing data and information within a geographical network of crops and irrigation systems, avoiding waste and watering which is unnecessary or excessive.

Claims

[Claim 1] A method for the iterative control of the irrigation for a flat crop comprising the steps of:

- setting (A) initial control data of the crop as a function of charac teristic parameters which define a configuration of a crop (P), said initial control data comprising a crop correction coefficient (K), a unit of time (T) for dispensing and a maximum degree of vigour (RGmax);

- measuring a current value of a reference evapotranspiration (ETO);

- dispensing (B) a quantity of water (ET) as a function of said initial data and said measured reference evapotranspiration (ETO);

- measuring a current value of the degree of vigour (RG) of the crop after a unit of time (T);

- checking whether the current value of the degree of vigour (RG) is equal to the maximum degree of vigour (RGmax);

- increasing (C) or reducing (D) the crop correction coefficient (K) if the current value of the measured degree of vigour (RG) of the crop deviates from said maximum degree of vigour (RGmax) in such a way as to modify a quantity of water (ET) dispensed.

[Claim 2] The control method according to claim 1, wherein said crop correction coefficient K is increased by a multiplication factor A1>1 or is reduced by a multiplication factor A2<1 for each number of iteration passes (n).

[Claim 3] The control method according to claim 1 or 2, wherein said crop correction coefficient K is increased by a multiplication factor D1 or by a multiplication factor D2 increased or decreased as a function of the number of iteration passes (n).

[Claim 4] The control method according to any one of the preceding claims, wherein the unit of time (T) can be set as a solar day or a relative fraction or a relative multiple thereof.

[Claim 5] A system for automatically controlling the irrigation of a flat crop comprising:

- an evapotranspiration sensor (2) configured for measuring a current value of a reference evapotranspiration (ETO);

- a vigour sensor (3) of the crop configured to provide a current value of the degree of vigour (RG) by analysing spectral emissions of the leaves of the crop;

- an actuator (4) for controlled dispensing of the water in commu nication with a hose (5) on which water release nozzles are connected for uniformly watering the crop;

- a computerised implementation device (1) configured for executing a method according to any one of the preceding claims.

[Claim 6] The control system according to claim 5, wherein said evapotran- spiration sensor (2), said vigour sensor (3) and said actuator (4) comprise respective communication lines (2a, 3a, 4a) with the imple mentation device (1) of the cable or radio type.

[Claim 7] The control system according to claim 5 or 6, wherein said imple mentation device is equipped with a user interface.

[Claim 8] The control system according to any one of claims 5 to 7, wherein said vigour sensor comprises one or more elements for measuring the re flection of the leaves configured to obtain degrees of vigour (RG) of the crop.