An automatic closed-loop control method for water and fertilizer mixing ratio

Abstract

The present application relates to irrigation control technology field, specifically to a kind of automatic closed-loop control method of water and fertilizer mixed proportioning.The present application is based on pipeline cumulative volume triggers sampling, and intercepts spatially aligned inlet fertilizer solution concentration sequence fragment and outlet fertilizer solution concentration sequence fragment at current sampling time, and then combines sequence matching result, assesses fertilizer solution transmission efficiency coefficient and sequence matching distortion coefficient, then combines pipeline instantaneous flow and target proportioning concentration, and the deviation of outlet fertilizer solution concentration relative to target proportioning concentration, obtains fertilizer injection pump driving parameter and controls fertilizer injection pump.The present application introduces the spatial sampling mechanism triggered by pipeline cumulative flow, eliminates the interference of pipeline flow rate fluctuation on control timing;Intercept the sequence fragment of spatially aligned inlet fertilizer solution concentration and outlet fertilizer solution concentration and match analysis, decouple pipeline transmission efficiency and Taylor dispersion, and then compensate fertilizer injection error quickly while avoiding control oscillation risk, improve water and fertilizer mixed proportioning precision.

Description

Technical Field

[0001] This invention relates to the field of irrigation regulation technology, specifically to an automated closed-loop regulation method for water and fertilizer mixing ratio. Background Technology

[0002] Modern agricultural irrigation systems typically employ fertigation technology, precisely mixing soluble fertilizers with irrigation water as needed and delivering the mixture with the irrigation water. This improves water and fertilizer utilization efficiency, saves labor costs, and precisely regulates crop growth. To adapt to the irrigation needs of different plots of land, the system often adopts a rotational irrigation mode. This involves switching solenoid valves to supply water to different irrigation areas in rotation, while dynamically adjusting the fertilizer pump output based on real-time flow to stabilize the outlet concentration.

[0003] However, the switching between irrigation seasons causes drastic fluctuations in the fluid velocity within the main irrigation pipeline. This alters the transmission time of the fluid from the injection point to the downstream concentration sensor, leading to mismatch in controller parameters based on fixed-time sampling, resulting in system oscillations or sluggish responses. Simultaneously, during long-distance transport, laminar flow tailing or turbulent diffusion caused by pipe wall friction induces longitudinal mixing (Taylor dispersion), causing nonlinear distortions in the concentration waveform detected by the sensor, such as peak suppression and widening. Existing methods often ignore waveform distortion, simply attributing low sensor readings to insufficient injection, thus performing incorrect gain compensation when the waveform is misaligned, leading to decreased mixing accuracy or even overshoot. Summary of the Invention

[0004] To address the technical problem of low accuracy in water-fertilizer mixing ratios in existing control methods, the present invention aims to provide an automated closed-loop control method for water-fertilizer mixing ratios. The specific technical solution adopted is as follows:

[0005] Real-time monitoring of pipeline flow; sampling triggered by pipeline cumulative volume, and synchronous collection of pipeline instantaneous flow, fertilizer inlet pressure and outlet fertilizer concentration at pipeline outlet at each sampling time; at each sampling time, acquisition of fertilizer pump drive parameters from the previous sampling time, and calculation of inlet fertilizer concentration at pipeline inlet by combining pipeline instantaneous flow and fertilizer inlet pressure.

[0006] At the current sampling time, construct the inlet fertilizer concentration sequence and the outlet fertilizer concentration sequence; calculate the fertilizer transport lag step based on the irrigation pipeline volume, and extract spatially aligned inlet fertilizer concentration sequence fragments and outlet fertilizer concentration sequence fragments from the inlet fertilizer concentration sequence and the outlet fertilizer concentration sequence, respectively, based on the fertilizer transport lag step.

[0007] Based on the matching results of sequence segments and the lag steps of fertilizer solution transmission, the fertilizer solution transmission efficiency coefficient and sequence matching distortion coefficient are obtained. Combined with the instantaneous flow rate of the pipeline, the target ratio concentration, and the deviation of the outlet fertilizer solution concentration from the target ratio concentration, the fertilizer injection pump driving parameters at the current sampling time are obtained and the fertilizer injection pump is adjusted.

[0008] Furthermore, sampling is triggered based on the cumulative volume of the pipeline, including:

[0009] The pipeline flow rate is integrated over time in real time to update the pipeline cumulative volume; whenever the pipeline cumulative volume reaches the preset flow rate volume, sampling is triggered and the corresponding time is recorded as a sampling time.

[0010] Furthermore, the method for obtaining the concentration of the inlet fertilizer solution includes:

[0011] At each sampling time, based on the deviation of the fertilizer injection port pressure from the preset reference pressure and the preset pressure sensitivity factor, the pump pressure influence factor is obtained; and the correction weight is determined based on the pump pressure influence factor.

[0012] At each sampling time, the calibrated fertilizer injection mass under the pre-calibrated unit driving parameters is weighted using the fertilizer injection pump driving parameters of the previous sampling time to obtain the initial fertilizer injection mass; the initial fertilizer injection mass is weighted using the correction weight to obtain the corrected fertilizer injection mass; the corrected fertilizer injection mass is divided by the instantaneous flow rate of the pipeline to obtain the inlet fertilizer concentration.

[0013] Furthermore, the method for obtaining the fertilizer solution transport lag steps includes:

[0014] The integer value obtained by dividing the irrigation pipe volume by the preset flow rate volume is used as the fertilizer solution delivery lag step.

[0015] Furthermore, the method for obtaining the inlet fertilizer solution concentration sequence fragment includes:

[0016] At the current sampling time, backtrack the fertilizer solution transmission lag step in the reverse direction of the time sequence to determine the window endpoint and determine the inlet sampling window of preset length; extract the inlet fertilizer solution concentration sequence segment within the inlet sampling window from the inlet fertilizer solution concentration sequence.

[0017] Furthermore, the method for obtaining the concentration sequence fragment of the exported fertilizer solution includes:

[0018] Backtracking in the reverse direction of the time sequence at the current sampling time, determine the preset length of the exit sampling window, and extract the exit fertilizer concentration sequence segment within the exit sampling window from the exit fertilizer concentration sequence.

[0019] Furthermore, the method for obtaining the fertilizer-liquid transport efficiency coefficient and the sequence matching distortion coefficient includes:

[0020] If the number of sampling steps corresponding to the current sampling time is less than the number of fertilizer solution transmission lag steps, let the fertilizer solution transmission efficiency coefficient be the preset steady-state value and let the sequence matching distortion coefficient be the preset distortion-free value.

[0021] If the number of sampling steps at the current sampling time is greater than or equal to the preset transition step size, the fertilizer liquid transmission efficiency coefficient and the sequence matching distortion coefficient are determined based on the matching results.

[0022] If the number of sampling steps corresponding to the current sampling time is greater than or equal to the number of fertilizer-liquid transport lag steps and less than the preset transition step size, the transition fertilizer-liquid transport efficiency coefficient is determined based on the matching result and fused with the preset steady-state value to obtain the fertilizer-liquid transport efficiency coefficient; the transition sequence matching distortion coefficient is determined based on the matching result and fused with the preset no-distortion value to obtain the sequence matching distortion coefficient.

[0023] Furthermore, based on the matching results, the fertilizer-solution transport efficiency coefficient and the sequence matching distortion coefficient are determined, including:

[0024] Obtain all feature matching pairs between the inlet fertilizer concentration sequence fragment and the outlet fertilizer concentration sequence fragment. Obtain the fertilizer transport efficiency coefficient based on the concentration difference between each inlet fertilizer concentration and the matching outlet fertilizer concentration. Obtain the sequence matching distortion coefficient based on the sequence number difference between each inlet fertilizer concentration and the matching outlet fertilizer concentration.

[0025] Furthermore, the method for obtaining the fertilizer injection pump drive parameters includes:

[0026] The fertilizer solution transmission efficiency coefficient after amplitude limiting is fused with the correction weight and then negatively correlated to obtain the fertilizer injection compensation weight; the instantaneous flow rate of the pipeline at the current sampling time is multiplied by the target ratio concentration to obtain the theoretical fertilizer injection mass; the theoretical fertilizer injection mass is divided by the calibrated fertilizer injection mass under the pre-calibrated unit driving parameters to obtain the initial basic driving parameters; the initial basic driving parameters are weighted using the fertilizer injection compensation weight to obtain the basic driving parameters.

[0027] Based on the deviation of the outlet fertilizer concentration relative to the target ratio concentration at the current sampling time, and the sequence matching distortion coefficient, and combined with the deviation adjustment driving parameter at the previous sampling time, the deviation adjustment driving parameter at the current sampling time is obtained.

[0028] The fertilizer injection pump driving parameters at the current sampling time are obtained by summing the deviation adjustment driving parameters and the basic driving parameters.

[0029] Furthermore, the method for obtaining the deviation adjustment driving parameters includes:

[0030] Based on the deviation of the outlet fertilizer concentration relative to the target ratio concentration at the current sampling time, the concentration deviation is determined; the negative correlation normalization result of the sequence matching distortion coefficient is used as the feedback adjustment weight; the fusion result of the preset integral gain and the concentration deviation is weighted using the feedback adjustment weight, and the weighted result is accumulated with the deviation adjustment driving parameter at the previous sampling time to obtain the deviation adjustment driving parameter.

[0031] The present invention has the following beneficial effects:

[0032] This invention monitors pipeline flow in real time and triggers sampling based on the cumulative pipeline volume, transforming the time-varying lag problem in traditional control into a steady process in the spatial domain. At each sampling moment, it simultaneously collects the pipeline instantaneous flow rate, fertilizer inlet pressure, and fertilizer concentration at the pipeline outlet. Then, at each sampling moment, it obtains the fertilizer pump drive parameters from the previous sampling moment and, combined with the pipeline instantaneous flow rate and fertilizer inlet pressure, calculates the inlet fertilizer concentration at the pipeline inlet after pump efficiency compensation. At the current sampling moment, it constructs inlet and outlet fertilizer concentration sequences. Based on the irrigation pipeline volume, it calculates the fertilizer transport lag steps and, based on the fertilizer transport lag... The invention employs a spatial sampling mechanism triggered by cumulative pipeline flow to eliminate the interference of pipeline flow velocity fluctuations on control timing. By extracting spatially aligned inlet and outlet fertilizer concentration sequence segments and performing matching analysis, pipeline transmission efficiency and Taylor dispersion are decoupled, thus rapidly compensating for injection errors while mitigating control oscillation risks and improving the accuracy of water-fertilizer mixing ratios. Furthermore, based on the matching results of these sequence segments and the fertilizer transmission lag steps, the fertilizer transmission efficiency coefficient (characterizing pipeline transmission loss) and sequence matching distortion coefficient (characterizing Taylor dispersion) are obtained. The current fertilization conditions are then analyzed in conjunction with the pipeline instantaneous flow rate and the target ratio concentration for rapid compensation. The deviation of the outlet fertilizer concentration from the target ratio concentration is analyzed for error compensation, and the fertilization pump drive parameters at the current sampling time are obtained and the fertilization pump is adjusted. Attached Figure Description

[0033] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a flowchart of an automated closed-loop control method for water and fertilizer mixing ratio provided in one embodiment of the present invention. Detailed Implementation

[0035] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of an automated closed-loop control method for water and fertilizer mixing ratio proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0037] The following description, in conjunction with the accompanying drawings, details the specific scheme of the automated closed-loop control method for water and fertilizer mixing ratio provided by this invention.

[0038] It should be noted that this invention is applicable to integrated water and fertilizer precision irrigation systems; the irrigation system typically includes a water source head, a fertilizer injection device, a delivery pipeline, and several solenoid valves distributed in the field for rotating irrigation zones; the fertilizer injection device (such as a Venturi fertilizer injector or an electric fertilizer pump) is usually installed at the head of the delivery pipeline to inject a high-concentration fertilizer stock solution into the flowing water. The mixed fertilizer solution is then transported to the field through the delivery pipeline. During the transport process, the fertilizer stock solution undergoes axial mixing and diffusion in the water flow; to achieve closed-loop control of fertilizer injection accuracy, a concentration sensor is usually installed downstream of the injection point to monitor the concentration of the mixed fertilizer solution in real time.

[0039] Please see Figure 1 The diagram illustrates a flowchart of an automated closed-loop control method for water and fertilizer mixing ratio according to an embodiment of the present invention, specifically including:

[0040] Step S1: Monitor pipeline flow rate in real time; trigger sampling based on pipeline cumulative volume, and synchronously collect pipeline instantaneous flow rate, fertilizer inlet pressure and outlet fertilizer concentration at pipeline outlet at each sampling time; at each sampling time, obtain the fertilizer pump drive parameters of the previous sampling time, and calculate the inlet fertilizer concentration at pipeline inlet by combining pipeline instantaneous flow rate and fertilizer inlet pressure.

[0041] In one embodiment of the present invention, the flow rate (unit: L / s) of the delivery pipeline is first collected in real time by an electromagnetic flow meter or ultrasonic flow meter installed on the delivery pipeline (required to be upstream of the fertilizer injection point) at a fixed high-frequency sampling frequency (e.g., 10Hz).

[0042] It should be noted that after acquiring the pipeline flow rate, the zero-flow reset monitoring logic is executed first to prevent continued fertilization during irrigation stops or irrigation rotation intervals, ensuring that fertilization control is only performed during periods of effective fluid flow to avoid the risk of dry running. The specific steps are as follows:

[0043] The collected pipeline flow rate Q is compared with the preset minimum effective flow rate threshold Qmin (e.g., set to 0.1 L / s, this value depends on the minimum reliable reading of the flow meter); when Q≤Qmin is detected, the zero flow timer starts to accumulate time; if the accumulated time exceeds the preset timeout protection threshold (e.g., 60 seconds), it is determined that the current irrigation system is in a stopped or switched state; once it is determined to be in a stopped state, a safety reset operation is forcibly executed: the fertilizer pump drive command is immediately set to zero, the fertilizer pump operation is stopped, until the pipeline flow rate recovers to above Qmin.

[0044] It should be noted that subsequent fertilizer injection is carried out when the pipeline flow rate Q > Qmin.

[0045] Considering that by integrating the real-time pipeline flow rate to obtain the cumulative volume of the pipeline, and then establishing a spatial sampling triggering mechanism that is not affected by flow velocity fluctuations, the time-varying lag problem in traditional control can be transformed into a steady process in the spatial domain, this embodiment of the invention further triggers sampling based on the cumulative volume of the pipeline, and simultaneously collects the instantaneous flow rate of the pipeline, the pressure at the fertilizer inlet, and the concentration of fertilizer solution at the outlet of the pipeline at each sampling moment.

[0046] The actual amount of fertilizer injected by the fertilizer injection pump depends not only on the fertilizer injection drive command, but also on the back pressure of the pipeline at the injection port (fertilizer port pressure). The higher the back pressure, the less fertilizer solution is actually injected into the pipeline (pump efficiency decreases). Collecting the fertilizer port pressure can help to evaluate the actual amount of fertilizer injected. The instantaneous flow rate of the pipeline and the fertilizer solution concentration at the pipeline outlet can help to estimate the fertilizer solution concentration at the pipeline inlet (i.e., the fertilizer concentration), which in turn helps to evaluate the fertilizer solution transmission situation and adaptively adjust the fertilizer injection pump.

[0047] Preferably, in one embodiment of the present invention, sampling is triggered based on the cumulative volume of the pipeline, including:

[0048] The pipeline flow rate is integrated over time in real time to update the pipeline cumulative volume; whenever the pipeline cumulative volume reaches the preset flow rate volume, sampling is triggered and the corresponding time is recorded as a sampling time.

[0049] Specifically, the pipeline flow rate (when Q > Qmin) is integrated in the time domain, and the integral represents the cumulative volume of the pipeline injected into the pipeline; a preset flow volume that determines the sampling resolution is set, with a value range of 0.1-1L, and 0.5L is used in this example; whenever the cumulative volume of the pipeline reaches the preset flow volume (i.e., every time the preset flow volume is accumulated in the pipeline), a sampling is triggered, and the triggering time is recorded as a sampling time; the time interval between sampling times may not be completely consistent.

[0050] Furthermore, at each sampling moment, the pipeline flow rate collected by the flow meter is read as the pipeline instantaneous flow rate; the pressure at the fertilizer injection port (outlet of the fertilizer injection pump or fertilizer injection point in the pipeline) is collected at each sampling moment using a pressure transmitter installed at the fertilizer injection port (unit: MPa); and the outlet fertilizer concentration (unit: mg / L) at each sampling moment is collected using a concentration sensor installed downstream of the fertilizer injection point.

[0051] Considering the continuity of the physical displacement of the fluid in the pipeline, the mass of fertilizer solution contained in the fluid micro-element (preset flow volume of fluid) injected into the pipeline between each sampling moment and the adjacent previous sampling moment is determined by the fertilizer injection command (i.e., fertilizer injection pump drive parameters) of the adjacent previous sampling moment; while the fertilizer injection port pressure affects the pump efficiency of the fertilizer injection pump, which in turn affects the actual amount of fertilizer injected into the pipeline. The instantaneous flow rate of the pipeline can help assess the dilution of the fertilizer injection volume in the fluid, and thus help assess the inlet fertilizer solution concentration at the pipeline inlet before dilution.

[0052] Based on this, the embodiments of the present invention further obtain the fertilizer pump driving parameters of the previous sampling time at each sampling time, and calculate the inlet fertilizer concentration at the pipeline inlet by combining the pipeline instantaneous flow rate and the fertilizer inlet pressure.

[0053] It should be noted that the fertilizer injection pump drive parameters are control commands output by the controller to the fertilizer injection pump actuator (such as the output frequency of the frequency converter, the PWM duty cycle, or the stroke frequency of the stepper motor, etc. In this example, the adjustment of the PWM duty cycle is taken as an example, and the unit is %). They represent the mechanical actuation force or injection rate target value required for the fertilizer injection pump to act between adjacent sampling times.

[0054] It should be noted that the fertilizer pump driving parameters at each sampling time are directly written into the historical data buffer for overwriting after acquisition. The fertilizer pump driving parameters at the first sampling time are directly set to the initial zero value, and the fertilizer pump driving parameters at each subsequent sampling time are continuously acquired according to the subsequent analysis process. The analysis and calculation process of the inlet fertilizer concentration at each (non-first) sampling time is the same. Here, we only take any sampling time as an example for analysis and description.

[0055] Preferably, in one embodiment of the present invention, considering that the pre-calibrated standard operating condition fertilizer inlet pressure (preset reference pressure) can help assess the deviation of the sampled fertilizer inlet pressure, by setting a preset pressure sensitivity factor characterizing the change of fertilizer pump displacement with back pressure, it can help quantify the pump efficiency attenuation or gain of the fertilizer pump, determine the pump pressure influence factor, and thus determine the correction weight of the fertilizer injection amount; and considering that by combining the fertilizer pump drive parameters at the previous sampling time and the calibrated fertilizer injection mass under the pre-calibrated unit drive parameters, the theoretical fertilizer injection mass at the previous sampling time can be determined, and by further combining the correction weight, the fertilizer injection mass pumped out by the pump head under the real back pressure can be restored, and then the inlet fertilizer concentration can be calculated by combining the pipeline instantaneous flow rate; therefore, the method for obtaining the inlet fertilizer concentration includes:

[0056] At each sampling time, the pump pressure influence factor is obtained based on the deviation of the fertilizer injection port pressure from the preset reference pressure and the preset pressure sensitivity factor; the correction weight is determined based on the pump pressure influence factor.

[0057] At each sampling time, the calibrated fertilizer injection mass under the pre-calibrated unit driving parameters is weighted using the fertilizer injection pump driving parameters of the previous sampling time to obtain the initial fertilizer injection mass; the initial fertilizer injection mass is weighted using the correction weight to obtain the corrected fertilizer injection mass; the corrected fertilizer injection mass is divided by the pipeline instantaneous flow rate to obtain the inlet fertilizer concentration.

[0058] As an example, firstly, a preset reference pressure is set to characterize the fertilizer inlet pressure under standard operating conditions, with a value range of 0.2-0.6 MPa; in this example, 0.3 MPa is used. The pressure deviation between the fertilizer inlet pressure at the sampling time and the preset reference pressure is calculated. Then, a preset pressure sensitivity factor is set to characterize the change in fertilizer pump displacement with back pressure (fertilizer inlet pressure), with a value range of 0.05-0.2 MPa. -1 In this example, 0.2 MPa is used. -1 ;

[0059] The pressure deviation is multiplied by the preset pressure sensitivity factor to obtain the pump pressure influence factor; the constant 1 is subtracted from the pump pressure influence factor, and the difference is truncated to obtain the correction weight (when the difference is less than the preset value, such as 0.1, the correction weight is forced to be 0.1, and the correction weight is a dimensionless parameter); where the constant 1 represents the fertilizer injection pump displacement (fertilizer injection quality) under standard operating conditions. The larger the pump pressure influence factor, the smaller the correction weight. When the correction factor is less than 1, it indicates that the pump efficiency is reduced and the actual fertilizer injection quality will be reduced.

[0060] The calibration fertilizer injection mass under pre-calibrated unit driving parameters is retrieved, with a value range of 1.0-5.0, and the unit is (mg / s) / %; the specific offline calibration process is as follows: Under the preset reference pressure, given multiple stepped driving parameters (such as 20%, 50%, and 80% of the range), the fertilizer injection mass (unit: mg / s, representing the fertilizer injection mass per unit time) stably output by the fertilizer injection pump under each driving parameter is measured; with the driving parameter as the abscissa and the fertilizer injection mass as the ordinate, the slope of the straight line is obtained through linear regression fitting, which is the calibration fertilizer injection mass under the unit driving parameters;

[0061] Further, the fertilizer injection pump drive parameters at the previous sampling time are read from the historical data buffer. The fertilizer injection pump drive parameters are multiplied by the calibrated fertilizer injection mass under the pre-calibrated unit drive parameters to obtain the initial fertilizer injection mass (unit: mg / s). Then, the correction weight is multiplied by the initial fertilizer injection mass to obtain the corrected fertilizer injection mass. Finally, the corrected fertilizer injection mass (unit: mg / s) is divided by the pipeline instantaneous flow rate (unit: L / s) to obtain the inlet fertilizer concentration (unit: mg / L).

[0062] Step S2: At the current sampling time, construct the inlet fertilizer concentration sequence and the outlet fertilizer concentration sequence; calculate the fertilizer transport lag step based on the irrigation pipeline volume, and based on the fertilizer transport lag step, extract spatially aligned inlet fertilizer concentration sequence fragments and outlet fertilizer concentration sequence fragments from the inlet fertilizer concentration sequence and the outlet fertilizer concentration sequence, respectively.

[0063] After obtaining the inlet and outlet fertilizer concentrations at each sampling time, the inlet and outlet fertilizer concentration sequences can be constructed at the current sampling time. This is to prepare for subsequent analysis of the effects of laminar flow tailing or turbulent diffusion caused by pipe wall friction after long-distance transport of fertilizer through pipelines, thereby evaluating the fertilizer transport efficiency coefficient and sequence matching distortion coefficient, and preparing for subsequent optimization of fertilizer injection pump drive parameters and precise control of the fertilizer injection pump.

[0064] Specifically, at the current sampling time, the inlet fertilizer concentration and outlet fertilizer concentration at all historical sampling times are sorted in chronological order to construct the inlet fertilizer concentration sequence and the outlet fertilizer concentration sequence; the construction of the chronological sequence is a well-known technical means and will not be elaborated further.

[0065] Considering that there is a fixed volume of pipe between the fertilizer injection point (referring to the pipe inlet) and the concentration sensor (referring to the pipe outlet), the newly injected fertilizer solution must flow through this volume before it can be detected by the concentration sensor. Therefore, the fertilizer solution transmission has a certain lag. The number of lag steps in fertilizer solution transmission can be calculated by using the volume of the irrigation pipe.

[0066] The number of lag steps in fertilizer solution transport characterizes the lag in fertilizer solution transport from a (spatial) sampling perspective, which prepares for subsequent extraction of spatially aligned inlet and outlet fertilizer solution concentration sequence fragments for matching, in order to analyze the fertilizer solution transport efficiency coefficient and sequence matching distortion coefficient.

[0067] Preferably, in one embodiment of the present invention, considering that under the sampling mechanism based on cumulative flow, a sampling data point is recorded for each flow of fertilizer solution passing through a preset flow volume; the lag (sampling) steps of fertilizer solution transport can be evaluated from a (spatial) sampling perspective by using the irrigation pipe volume between the pipe inlet and the pipe outlet and the preset flow volume; therefore, the method for obtaining the lag steps of fertilizer solution transport includes:

[0068] The integer value obtained by dividing the irrigation pipe volume by the preset flow rate volume is used as the fertilizer solution transmission lag step N.

[0069] In this example, the rounding up method is used. Rounding to the nearest whole number can also be used, which will not be elaborated further.

[0070] After determining the lag step of fertilizer solution transport, spatially aligned inlet fertilizer solution concentration sequence fragments and outlet fertilizer solution concentration sequence fragments are further extracted for matching, providing a basis for subsequent matching.

[0071] Preferably, in one embodiment of the present invention, considering that the fertilizer solution at the pipe outlet at the current sampling time k may be the fertilizer solution at the pipe inlet at the sampling time kN, in order to ensure spatial alignment, the fertilizer solution transmission lag step N can be traced back in the reverse direction of time to extract a sampling window of a preset length; then the method for obtaining the inlet fertilizer solution concentration sequence segment includes:

[0072] At the current sampling time, backtrack the fertilizer solution transmission lag step in the reverse direction of the time sequence to determine the window endpoint and determine the inlet sampling window of preset length; extract the inlet fertilizer solution concentration sequence segment within the inlet sampling window from the inlet fertilizer solution concentration sequence.

[0073] As an example, backtrack N sampling times from the current sampling time k to obtain the sampling time kN corresponding to the end of the window; further set a preset length W to determine the inlet sampling window, and extract the inlet fertilizer concentration sequence segment within the inlet sampling window from the inlet fertilizer concentration sequence.

[0074] In this example, the preset length W should not be too short to cover the waveform broadening that may be caused by fluid mixing, and should not be too long to meet the real-time requirements of calculation time; a value of 20 is recommended.

[0075] Preferably, in one embodiment of the present invention, the method for obtaining the concentration sequence fragment of the exported fertilizer solution includes:

[0076] Backtracking in the reverse direction of the time sequence at the current sampling time, determine the preset length of the exit sampling window, and extract the exit fertilizer concentration sequence segment within the exit sampling window from the exit fertilizer concentration sequence.

[0077] As an example, taking the current sampling time k as the end point of the window, we backtrack W sampling times to determine the exit sampling window of length W, and extract the exit fertilizer concentration sequence segment within the exit sampling window from the exit fertilizer concentration sequence.

[0078] It should be noted that the export fertilizer concentration sequence fragment and the inlet fertilizer concentration sequence fragment are of the same length, but they are out of sync in terms of the number of fertilizer transport lag steps. They are two sequence fragments with a causal relationship of transport lag. There is a possibility that the preset length W exceeds the boundary (sampling start point), so a forced padding operation is performed to satisfy the sequence length W.

[0079] Step S3: Based on the matching results of the sequence segments and the lag steps of fertilizer solution transmission, obtain the fertilizer solution transmission efficiency coefficient and the sequence matching distortion coefficient. Combined with the instantaneous flow rate of the pipeline and the target ratio concentration, as well as the deviation of the outlet fertilizer solution concentration from the target ratio concentration, obtain the fertilizer injection pump driving parameters at the current sampling time and adjust the fertilizer injection pump.

[0080] Since the fluid has a fixed volumetric delay (fertilizer liquid transport lag step) in the pipeline, if the newly injected fertilizer liquid at the pipeline inlet has not yet flowed through the pipeline outlet, forced matching will affect the accuracy of the fertilizer liquid transport efficiency coefficient analysis, and may be misjudged as the fertilizer injection amount being too low, leading to excessive overshoot of the fertilizer injection pump; based on this, the embodiments of the present invention will obtain the fertilizer liquid transport efficiency coefficient and the sequence matching distortion coefficient based on the matching result of the sequence segment and the fertilizer liquid transport lag step.

[0081] The fertilizer solution transport efficiency coefficient characterizes the physical transport efficiency of the fertilizer solution, and indirectly reflects the transport loss, such as whether the pipeline is leaking or whether the fertilizer pump is worn out. The sequence matching distortion coefficient characterizes the degree of mixing of fluid in the pipeline due to Taylor dispersion and other reasons, which can help avoid the risk of oscillation in subsequent control.

[0082] Preferably, in one embodiment of the present invention, since the fluid has a fixed volumetric delay in the pipeline, it needs to be classified and discussed. If the pipeline is not yet filled with fertilizer solution, the matching results of the sequence fragments cannot reflect the pipeline transmission efficiency and Taylor dispersion. Therefore, the fertilizer solution transmission efficiency coefficient and the sequence matching distortion coefficient can be directly set. If the pipeline is in the initial transition stage of being filled with fertilizer solution, there may be boundary effects (such as some concentration values ​​of 0 in the sequence fragments) leading to poor matching analysis results of the sequence fragments. In this case, the matching analysis results can be combined with preset values ​​for fusion transition analysis. If the pipeline is in the steady-state stage of being filled with fertilizer solution, the matching results of the sequence fragments have a high confidence level for evaluating the pipeline transmission efficiency and Taylor dispersion. Therefore, the method for obtaining the fertilizer solution transmission efficiency coefficient and the sequence matching distortion coefficient includes:

[0083] If the number of sampling steps corresponding to the current sampling time is less than the number of fertilizer solution transmission lag steps, let the fertilizer solution transmission efficiency coefficient be the preset steady-state value and let the sequence matching distortion coefficient be the preset distortion-free value.

[0084] If the number of sampling steps at the current sampling time is greater than or equal to the preset transition step size, the fertilizer liquid transmission efficiency coefficient and the sequence matching distortion coefficient are determined based on the matching results.

[0085] If the number of sampling steps corresponding to the current sampling time is greater than or equal to the number of fertilizer-liquid transport lag steps and less than the preset transition step size, the transition fertilizer-liquid transport efficiency coefficient is determined based on the matching result and fused with the preset steady-state value to obtain the fertilizer-liquid transport efficiency coefficient; the transition sequence matching distortion coefficient is determined based on the matching result and fused with the preset no-distortion value to obtain the sequence matching distortion coefficient.

[0086] As an example, the classification discussion is as follows:

[0087] (1) If the number of sampling steps corresponding to the current sampling time is less than the number of fertilizer liquid transmission lag steps (k < N), it indicates that the pipeline is not yet full of fertilizer liquid; let the fertilizer liquid transmission efficiency coefficient be the preset steady state value 1, that is, assume that there is no transmission loss; let the sequence matching distortion coefficient be the preset distortion-free value 0, that is, assume that there is no Taylor diffusion.

[0088] (2) If the number of sampling steps corresponding to the current sampling time is greater than or equal to the preset transition step size (k≥N+D), it indicates that the pipeline is in a steady state filled with fertilizer solution; where N+D is the preset transition step size, and D is 50 in this example; further determine the fertilizer solution transmission efficiency coefficient and the sequence matching distortion coefficient based on the matching results;

[0089] In a preferred embodiment of the present invention, determining the fertilizer-liquid transport efficiency coefficient and the sequence matching distortion coefficient based on the matching results includes:

[0090] Obtain all feature matching pairs between the inlet fertilizer concentration sequence fragment and the outlet fertilizer concentration sequence fragment. Obtain the fertilizer transport efficiency coefficient based on the concentration difference between each inlet fertilizer concentration and the matching outlet fertilizer concentration. Obtain the sequence matching distortion coefficient based on the sequence number difference between each inlet fertilizer concentration and the matching outlet fertilizer concentration.

[0091] As an example, the Dynamic Time Warping (DTW) algorithm can be used to obtain all feature matching pairs between the inlet fertilizer concentration sequence fragment and the outlet fertilizer concentration sequence fragment. This is a well-known technique and will not be elaborated further. The feature matching pairs may contain one-to-one, one-to-many, or many-to-one matching relationships.

[0092] For each feature matching pair, the outlet fertilizer concentration is used as the numerator, the inlet fertilizer concentration that matches it is used as the denominator, and the ratio is used as the transmission efficiency sub-parameter. The transmission efficiency sub-parameters corresponding to all feature matching pairs are averaged to obtain the fertilizer transmission efficiency coefficient. Then, the square root of the average of the squared differences between the inlet and outlet fertilizer concentrations in the corresponding sequence segments of each feature matching pair is taken to obtain the sequence matching distortion coefficient.

[0093] When the concentration of the inlet fertilizer solution is 0 (or below the effective detection limit of the sensor), the matching data pair is considered invalid data outside the fertilizer injection cycle and is discarded, and is not included in the averaging calculation of the fertilizer solution transmission efficiency coefficient.

[0094] As another example, the absolute value of the concentration difference between each inlet fertilizer concentration and each outlet fertilizer concentration is calculated. The mean of the inlet fertilizer concentration in the inlet fertilizer concentration sequence segment is added to a very small non-zero concentration value such as 0.01 (unit: mg / L) as a standardization constant. The absolute value of the concentration difference is divided by the standardization constant to remove the dimension and obtain the concentration matching cost.

[0095] Calculate the sequence number difference between the inlet fertilizer concentration and the outlet fertilizer concentration in the corresponding sequence segment. Divide the square of the sequence number difference by the square of the preset length W to normalize and eliminate the influence of segment length, and obtain the sequence number matching cost. The sequence number matching cost represents the lag matching cost at the sampling time.

[0096] Finally, the concentration matching cost and the sequence number matching cost are weighted and summed with weights of 0.5 and 0.5 respectively to obtain the matching cost between each inlet fertilizer concentration and each outlet fertilizer concentration.

[0097] Further, a matching cost matrix is ​​constructed using the matching cost, where the element in the i-th row and j-th column of the matching cost matrix represents the matching cost between the i-th inlet fertilizer concentration and the j-th outlet fertilizer concentration. Then, the minimum weight complete matching of the matching cost matrix is ​​solved using the Hungarian algorithm to obtain the optimal matching mapping relationship between the inlet fertilizer concentration and the outlet fertilizer concentration. The optimal matching mapping relationship includes the unique optimal one-to-one matching relationship between the inlet fertilizer concentration and the outlet fertilizer concentration in the two sequence segments.

[0098] The fertilizer solution concentration at each outlet is taken as the numerator, the inlet fertilizer solution concentration that matches it is taken as the denominator, and the ratio is taken as the transmission efficiency sub-parameter. The average of the transmission efficiency sub-parameters corresponding to all optimal matching mapping relationships is used to obtain the fertilizer solution transmission efficiency coefficient.

[0099] In each optimal one-to-one matching relationship, the square root of the average of the squared differences between the inlet fertilizer concentration and the outlet fertilizer concentration in the corresponding sequence segment is taken to obtain the sequence matching distortion coefficient.

[0100] In other examples, cross-correlation analysis can also be used to determine the matching relationship. This, along with the DTW algorithm and the Hungarian algorithm mentioned above, are well-known techniques and will not be elaborated further.

[0101] (3) If the number of sampling steps corresponding to the current sampling time is greater than or equal to the number of fertilizer liquid transmission lag steps and less than the preset transition step length (N≤k<N+D), it indicates that the pipeline is in the initial transition stage of being filled with fertilizer liquid; then the transition fertilizer liquid transmission efficiency coefficient and the transition sequence matching distortion coefficient are first determined based on the matching results. The method of obtaining them is the same as the method of obtaining the fertilizer liquid transmission efficiency coefficient and the sequence matching distortion coefficient in (2), and will not be repeated here.

[0102] Further determine the transition weights ,along with As the transition weight increases, the transition weight will gradually increase, representing a smooth change in the transition weight from the transition stage to the steady-state stage; the transition weight... Weighted average of the transition fertilizer liquid transport efficiency coefficient, using The preset steady-state value 1 is weighted, and the weighted sum is used as the fertilizer-liquid transport efficiency coefficient. Similarly, the transition sequence matching distortion coefficient can be weighted and fused with the preset undistorted value to obtain the sequence matching distortion coefficient.

[0103] Considering that at the current sampling moment, after obtaining the fertilizer solution transmission efficiency coefficient, the current fertilizer injection conditions (transmission loss, flow rate) can be analyzed based on the pipeline instantaneous flow rate and the target ratio concentration, which can help evaluate the benchmark driving parameters for feedforward compensation adjustment; and the deviation of the outlet fertilizer solution concentration from the target ratio concentration can help evaluate the control deviation, and the combination with the sequence matching distortion coefficient can help evaluate the signal quality and avoid misadjustment.

[0104] Based on this, in this embodiment of the invention, after obtaining the fertilizer solution transmission efficiency coefficient and the sequence matching distortion coefficient, the instantaneous flow rate of the pipeline and the target ratio concentration, as well as the deviation of the outlet fertilizer solution concentration from the target ratio concentration, are combined to obtain the fertilizer injection pump driving parameters at the current sampling time and adjust the fertilizer injection pump.

[0105] Considering that instantaneous sensor anomalies may cause extreme fluctuations in the fertilizer solution transmission efficiency coefficient, thereby affecting the subsequent control effect, the fertilizer solution transmission efficiency coefficient can first be limited to protect engineering safety. Furthermore, the fertilizer injection compensation weight can be determined by combining the correction weight that characterizes pump efficiency, in preparation for subsequent compensation adjustment. Also, considering that the instantaneous flow rate of the pipeline and the target ratio concentration at the current sampling time can be used to evaluate the theoretical fertilizer injection quality, and then the initial basic driving parameters can be determined by combining the calibrated fertilizer injection quality under the pre-calibrated unit driving parameters. Finally, the basic driving parameters can be comprehensively evaluated by combining the fertilizer injection compensation weight.

[0106] Considering that the deviation of the fertilizer solution concentration from the target ratio can help assess the control deviation, and the sequence matching distortion coefficient can help assess the signal quality and avoid misadjustment; furthermore, by combining the fertilizer pump drive parameters at the previous sampling time, the cumulative error can be assessed to prepare for subsequent control.

[0107] Based on this, in a preferred embodiment of the present invention, the method for obtaining the fertilizer injection pump drive parameters includes:

[0108] The fertilizer-liquid transmission efficiency coefficient after amplitude limiting is fused with the correction weight and then negatively correlated to obtain the fertilizer injection compensation weight; the instantaneous flow rate of the pipeline at the current sampling time is multiplied by the target ratio concentration to obtain the theoretical fertilizer injection mass; the theoretical fertilizer injection mass is divided by the calibrated fertilizer injection mass under the pre-calibrated unit driving parameters to obtain the initial basic driving parameters; the initial basic driving parameters are weighted using the fertilizer injection compensation weight to obtain the basic driving parameters.

[0109] Based on the deviation of the outlet fertilizer concentration relative to the target ratio concentration at the current sampling time, and the sequence matching distortion coefficient, and combined with the deviation adjustment driving parameters at the previous sampling time, the deviation adjustment driving parameters at the current sampling time are obtained.

[0110] By summing the deviation adjustment driving parameters and the basic driving parameters, the fertilizer injection pump driving parameters at the current sampling time are obtained.

[0111] As an example, the fertilizer solution transfer efficiency coefficient is limited to between 0.5 and 1.5. If the fertilizer solution transfer efficiency coefficient at the current sampling time is less than 0.5, the limited fertilizer solution transfer efficiency coefficient is set to 0.5. If the fertilizer solution transfer efficiency coefficient at the current sampling time is greater than 1.5, the limited fertilizer solution transfer efficiency coefficient is set to 1.5. When it is within the range, it is equal to the original value.

[0112] Multiply the fertilizer solution transmission efficiency coefficient after amplitude limiting by the correction weight, and take the reciprocal of the product to obtain the fertilizer injection compensation weight through negative correlation mapping; multiply the instantaneous flow rate of the pipeline at the current sampling time (unit: L / s) by the target ratio concentration (unit: mg / L) to obtain the theoretical fertilizer injection mass (unit: mg / s, representing the theoretical fertilizer injection mass per unit time).

[0113] Divide the theoretical fertilizer injection mass (unit: mg / s) by the calibrated fertilizer injection mass (unit: (mg / s) / %) under the pre-calibrated unit driving parameters to obtain the initial basic driving parameters; multiply the fertilizer injection compensation weight by the initial basic driving parameters to obtain the basic driving parameters;

[0114] Further obtain the deviation adjustment driving parameters at the current sampling time;

[0115] In a preferred embodiment of the present invention, the method for obtaining the deviation adjustment driving parameters includes:

[0116] Based on the deviation of the outlet fertilizer concentration relative to the target ratio concentration at the current sampling time, the concentration deviation is determined; the negative correlation normalization result of the sequence matching distortion coefficient is used as the feedback adjustment weight; the fusion result of the preset integral gain and concentration deviation is weighted using the feedback adjustment weight, and the weighted result is accumulated with the deviation adjustment driving parameter at the previous sampling time to obtain the deviation adjustment driving parameter.

[0117] As an example, the difference between the current sampling time's outlet fertilizer concentration and the target concentration is taken as the concentration deviation (unit: mg / L). The sequence matching distortion coefficient is added to a constant of 1 and then divided by its reciprocal to achieve negative correlation normalization. The reciprocal is used as the feedback adjustment weight. The larger the sequence matching distortion coefficient, the smaller the feedback adjustment weight, and the lower the confidence level of the concentration deviation assessed by the sensor. Furthermore, a preset integral gain is set, with a value range of 0.1-0.5 (unit: % / (mg / L)). In this example, it is set to 0.2.

[0118] The feedback adjustment weight (dimensionless parameter), the preset integral gain (unit: % / (mg / L)) and the concentration deviation (unit: mg / L) are multiplied together, and the product is added to the deviation adjustment driving parameter of the previous sampling time to obtain the deviation adjustment driving parameter; wherein, the deviation adjustment driving parameter of the previous sampling time is read from the historical data buffer, and the deviation adjustment driving parameter of the first sampling time is directly set to the initial zero value.

[0119] Finally, the deviation adjustment driving parameters are added to the basic driving parameters to obtain the fertilizer pump driving parameters at the current sampling time. In order to protect the actuator of the fertilizer pump, the fertilizer pump driving parameters are limited (0-1) and then sent to the fertilizer pump driving circuit through the I / O interface to adjust the PWM duty cycle.

[0120] The fertilizer injection pump drive parameters at the current sampling time are written into the historical data buffer for storage, making it easier to read later.

[0121] In summary, this invention monitors pipeline flow in real time; it triggers sampling based on the cumulative volume of the pipeline, and simultaneously collects the instantaneous flow rate, fertilizer inlet pressure, and outlet fertilizer concentration at each sampling moment; at each sampling moment, it obtains the fertilizer pump driving parameters from the previous sampling moment, and calculates the inlet fertilizer concentration at the pipeline inlet by combining the pipeline instantaneous flow rate and fertilizer inlet pressure; at the current sampling moment, it constructs an inlet fertilizer concentration sequence and an outlet fertilizer concentration sequence; it calculates the fertilizer transport lag step based on the irrigation pipeline volume, and extracts spatially aligned inlet and outlet fertilizer concentration sequence segments from the inlet and outlet fertilizer concentration sequences based on the fertilizer transport lag step; based on the sequence segment matching results and the fertilizer transport lag step, it obtains the fertilizer transport efficiency coefficient and sequence matching distortion coefficient, and combines the pipeline instantaneous flow rate, target ratio concentration, and the deviation of the outlet fertilizer concentration from the target ratio concentration to obtain the fertilizer pump driving parameters at the current sampling moment and adjusts the fertilizer pump. This invention introduces a spatial sampling mechanism triggered by pipeline cumulative flow to eliminate the interference of pipeline flow velocity fluctuations on control timing; it extracts and matches spatially aligned sequence segments of inlet and outlet fertilizer concentrations to decouple pipeline transmission efficiency and Taylor diffusion, thereby quickly compensating for fertilizer injection errors while avoiding control oscillation risks and improving the accuracy of water-fertilizer mixing ratio.

[0122] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0123] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. An automated closed-loop control method for water and fertilizer mixing ratio, characterized in that, The method includes: Real-time monitoring of pipeline flow; sampling triggered by pipeline cumulative volume, and synchronous collection of pipeline instantaneous flow, fertilizer inlet pressure and outlet fertilizer concentration at pipeline outlet at each sampling time; at each sampling time, acquisition of fertilizer pump drive parameters from the previous sampling time, and calculation of inlet fertilizer concentration at pipeline inlet by combining pipeline instantaneous flow and fertilizer inlet pressure. At the current sampling time, construct the inlet fertilizer concentration sequence and the outlet fertilizer concentration sequence; calculate the fertilizer transport lag step based on the irrigation pipeline volume, and extract spatially aligned inlet fertilizer concentration sequence fragments and outlet fertilizer concentration sequence fragments from the inlet fertilizer concentration sequence and the outlet fertilizer concentration sequence, respectively, based on the fertilizer transport lag step. Based on the matching results of sequence segments and the lag steps of fertilizer solution transmission, the fertilizer solution transmission efficiency coefficient and sequence matching distortion coefficient are obtained. Combined with the instantaneous flow rate of the pipeline, the target ratio concentration, and the deviation of the outlet fertilizer solution concentration from the target ratio concentration, the fertilizer injection pump driving parameters at the current sampling time are obtained and the fertilizer injection pump is adjusted.

2. The automated closed-loop control method for water and fertilizer mixing ratio according to claim 1, characterized in that, Sampling is triggered based on the cumulative volume of the pipeline, including: The pipeline flow rate is integrated over time in real time to update the pipeline cumulative volume; whenever the pipeline cumulative volume reaches the preset flow rate volume, sampling is triggered and the corresponding time is recorded as a sampling time.

3. The automated closed-loop control method for water and fertilizer mixing ratio according to claim 1, characterized in that, The method for obtaining the concentration of the inlet fertilizer solution includes: At each sampling time, based on the deviation of the fertilizer injection port pressure from the preset reference pressure and the preset pressure sensitivity factor, the pump pressure influence factor is obtained; and the correction weight is determined based on the pump pressure influence factor. At each sampling time, the calibrated fertilizer injection mass under the pre-calibrated unit driving parameters is weighted using the fertilizer injection pump driving parameters of the previous sampling time to obtain the initial fertilizer injection mass; the initial fertilizer injection mass is weighted using the correction weight to obtain the corrected fertilizer injection mass; the corrected fertilizer injection mass is divided by the instantaneous flow rate of the pipeline to obtain the inlet fertilizer concentration.

4. The automated closed-loop control method for water and fertilizer mixing ratio according to claim 1 or 2, characterized in that, The method for obtaining the fertilizer solution transport lag steps includes: The integer value obtained by dividing the irrigation pipe volume by the preset flow rate volume is used as the fertilizer solution delivery lag step.

5. The automated closed-loop control method for water and fertilizer mixing ratio according to claim 1, characterized in that, The method for obtaining the inlet fertilizer solution concentration sequence fragment includes: At the current sampling time, backtrack the fertilizer solution transmission lag step in the reverse direction of the time sequence to determine the window endpoint and determine the inlet sampling window of preset length; extract the inlet fertilizer solution concentration sequence segment within the inlet sampling window from the inlet fertilizer solution concentration sequence.

6. The automated closed-loop control method for water and fertilizer mixing ratio according to claim 1, characterized in that, The method for obtaining the export fertilizer solution concentration sequence fragment includes: Backtracking in the reverse direction of the time sequence at the current sampling time, determine the preset length of the exit sampling window, and extract the exit fertilizer concentration sequence segment within the exit sampling window from the exit fertilizer concentration sequence.

7. The automated closed-loop control method for water and fertilizer mixing ratio according to claim 1, characterized in that, The methods for obtaining the fertilizer-liquid transport efficiency coefficient and the sequence matching distortion coefficient include: If the number of sampling steps corresponding to the current sampling time is less than the number of fertilizer solution transmission lag steps, let the fertilizer solution transmission efficiency coefficient be the preset steady-state value and let the sequence matching distortion coefficient be the preset distortion-free value. If the number of sampling steps at the current sampling time is greater than or equal to the preset transition step size, the fertilizer liquid transmission efficiency coefficient and the sequence matching distortion coefficient are determined based on the matching results. If the number of sampling steps corresponding to the current sampling time is greater than or equal to the number of fertilizer-liquid transport lag steps and less than the preset transition step size, the transition fertilizer-liquid transport efficiency coefficient is determined based on the matching result and fused with the preset steady-state value to obtain the fertilizer-liquid transport efficiency coefficient; the transition sequence matching distortion coefficient is determined based on the matching result and fused with the preset no-distortion value to obtain the sequence matching distortion coefficient.

8. The automated closed-loop control method for water and fertilizer mixing ratio according to claim 7, characterized in that, The fertilizer-solution transport efficiency coefficient and sequence matching distortion coefficient are determined based on the matching results, including: Obtain all feature matching pairs between the inlet fertilizer concentration sequence fragment and the outlet fertilizer concentration sequence fragment. Obtain the fertilizer transport efficiency coefficient based on the concentration difference between each inlet fertilizer concentration and the matching outlet fertilizer concentration. Obtain the sequence matching distortion coefficient based on the sequence number difference between each inlet fertilizer concentration and the matching outlet fertilizer concentration.

9. The automated closed-loop control method for water and fertilizer mixing ratio according to claim 3, characterized in that, The method for obtaining the fertilizer injection pump drive parameters includes: The fertilizer solution transmission efficiency coefficient after amplitude limiting is fused with the correction weight and then negatively correlated to obtain the fertilizer injection compensation weight; the instantaneous flow rate of the pipeline at the current sampling time is multiplied by the target ratio concentration to obtain the theoretical fertilizer injection mass; the theoretical fertilizer injection mass is divided by the calibrated fertilizer injection mass under the pre-calibrated unit driving parameters to obtain the initial basic driving parameters; the initial basic driving parameters are weighted using the fertilizer injection compensation weight to obtain the basic driving parameters. Based on the deviation of the outlet fertilizer concentration relative to the target ratio concentration at the current sampling time, and the sequence matching distortion coefficient, and combined with the deviation adjustment driving parameter at the previous sampling time, the deviation adjustment driving parameter at the current sampling time is obtained. The fertilizer injection pump driving parameters at the current sampling time are obtained by summing the deviation adjustment driving parameters and the basic driving parameters.

10. The automated closed-loop control method for water and fertilizer mixing ratio according to claim 9, characterized in that, The method for obtaining the deviation adjustment driving parameters includes: Based on the deviation of the outlet fertilizer concentration relative to the target ratio concentration at the current sampling time, the concentration deviation is determined; the negative correlation normalization result of the sequence matching distortion coefficient is used as the feedback adjustment weight; the fusion result of the preset integral gain and the concentration deviation is weighted using the feedback adjustment weight, and the weighted result is accumulated with the deviation adjustment driving parameter at the previous sampling time to obtain the deviation adjustment driving parameter.

Images