A method and system for accurately controlling the fertilization flow rate of a water-fertilizer integrated machine for economic forest tree species

Abstract

The present application relates to the technical field of agricultural fertilization control, and specifically to a method and system for precisely controlling the fertilizer flow rate of an integrated water and fertilizer machine for economic forest tree species. The method comprises: collecting real-time water and fertilizer pressure data and water and fertilizer flow data in the water and fertilizer mixing pipe at the fertilizer nozzle of each tree; analyzing the fluctuation of the water and fertilizer flow data of each tree within a preset period before each collection moment, and determining the fluctuation trend influence coefficient of each tree at each collection moment; determining the upstream trend influence coefficient and water and fertilizer flow deviation of each tree at each collection moment; determining the fluctuation difference value of each tree in the same row at each collection moment; determining the proportional coefficient adjustment value of each tree at each collection moment; and determining the proportional term parameter of the PID control algorithm to control the fertilizer flow rate of each tree. The present application aims to improve the control accuracy of the fertilizer flow rate of each tree.

Description

Technical Field

[0001] The present application relates to the technical field of agricultural fertilization control, and specifically to a method and system for accurately controlling the fertilization flow of an integrated water and fertilizer machine for economic forest tree species. Background Art

[0002] The all-in-one water and fertilizer machine for economic forest tree species is a new type of intelligent agricultural equipment that integrates functions such as water-fertilizer ratio, mixing, transportation and spraying. It can mix water and fertilizer into water and fertilizer according to the growth characteristics and fertilizer requirements of different economic forest tree species, and realize directional, quantitative and timed irrigation and fertilization of various tree species in the planting field to meet the water and nutrition needs of different tree species.

[0003] To achieve more precise fertilization for each tree in a field of commercial forest species, an electric valve is typically installed at each tree's fertilizer nozzle, and control technology is used to control the fertilizer flow rate from the nozzle. The proportional term parameter in traditional PID control algorithms is usually a fixed value selected based on experience. However, due to the complex spatial distribution of water and fertilizer mixing pipes in the field and the instability of water pressure in the water and fertilizer mixing pipes, the water and fertilizer flow rate at the fertilizer nozzle varies, making traditional PID control algorithms ineffective in controlling the fertilizer flow rate for each tree. Summary of the Invention

[0004] In view of the above, it is necessary to provide a method and system for accurately controlling the fertilizer flow rate of an integrated water and fertilizer machine for economic forest tree species. Compared with the traditional method for controlling the fertilizer flow rate of an integrated water and fertilizer machine, the control accuracy of the fertilizer flow rate for each tree is improved:

[0005] In a first aspect, an embodiment of the present application provides a method for accurately controlling the fertilization flow rate of an integrated water and fertilizer machine for economic forest tree species, the method comprising the following steps:

[0006] At the fertilizer nozzle of each tree, the water and fertilizer pressure data and water and fertilizer flow data in the water and fertilizer mixing pipe are collected in real time and recorded as the water and fertilizer pressure data and water and fertilizer flow data of each tree;

[0007] Analyze the fluctuation of water and fertilizer flow data for each tree within a preset period of time before each collection time, and determine the fluctuation trend influence coefficient of each tree at each collection time;

[0008] Obtain the trees upstream of the water and fertilizer mixing pipeline at each tree's location, analyze the distance between each tree and its upstream trees, and the changes in water and fertilizer flow data of each upstream tree within a preset period before each collection time, and determine the upstream trend influence coefficient of each tree at each collection time;

[0009] Analyze the distribution of water and fertilizer flow data for each tree within a preset time period before each collection moment, and determine the water and fertilizer flow deviation of each tree at each collection moment by combining the fluctuation trend influence coefficient, the upstream trend influence coefficient, and the preset water and fertilizer flow value required for each tree;

[0010] Analyze the differences in the degree of dispersion of water and fertilizer pressure data between each tree and the trees in the same row within a preset period before each collection time, and determine the fluctuation difference value of each tree in the same row at each collection time;

[0011] Comprehensively analyzing the water and fertilizer flow deviation and the same-row fluctuation difference, as well as the discreteness of each tree, to determine the proportional coefficient adjustment value of each tree at each collection moment;

[0012] Based on the proportional coefficient adjustment value, the proportional term parameter of the PID control algorithm is determined to control the fertilizer flow rate of each tree.

[0013] In one embodiment, the process of determining the fluctuation trend influence coefficient is as follows:

[0014] Arrange the water and fertilizer flow data of each tree within a preset time period before each collection moment in chronological order to form a water and fertilizer flow sequence for each tree at each collection moment;

[0015] The discrete degree of each preset number of consecutive adjacent data in each water and fertilizer flow sequence is recorded as the flow discrete degree;

[0016] Arrange all the flow discreteness corresponding to each tree at each collection time in time sequence to form a flow discreteness sequence of each tree at each collection time, and obtain a fitting straight line for all data in each flow discreteness sequence;

[0017] The fluctuation trend influence coefficient is positively correlated with the slope of the fitting straight line.

[0018] In one embodiment, the upstream trend influence coefficient is determined as follows:

[0019] Obtain the fitting straight line of all data in the water and fertilizer flow series of each upstream tree for each tree, and record it as the flow fitting straight line;

[0020] The upstream trend influence coefficient is positively correlated with the slope of the flow fitting curve and negatively correlated with the distance.

[0021] In one embodiment, the process of determining the water and fertilizer flow deviation is as follows:

[0022] Calculate the mean of all data in each water and fertilizer flow series;

[0023] Determine the actual water and fertilizer flow value of each tree at each collection time by combining the mean, the upstream trend influence coefficient, and the fluctuation trend influence coefficient;

[0024] The water and fertilizer flow deviation is the difference between the actual water and fertilizer flow value and the preset water and fertilizer flow value.

[0025] In one embodiment, the actual water and fertilizer flow rate value is determined as follows:

[0026] Calculating a ratio of the upstream trend influence coefficient to the fluctuation trend influence coefficient;

[0027] The actual water and fertilizer flow value is the product of the mean value and the ratio.

[0028] In one embodiment, the process of determining the same-row fluctuation difference value is as follows:

[0029] The dispersion degree of water and fertilizer pressure data of each tree within the preset time period before each collection moment is recorded as pressure dispersion degree;

[0030] The difference in the degree of pressure dispersion between each tree and the trees in the same row is recorded as dispersion difference;

[0031] The same-row fluctuation difference value is the mean of all the discrete differences corresponding to each tree.

[0032] In one embodiment, the process of determining the proportional coefficient adjustment value is as follows:

[0033] Calculating a fusion result of the pressure dispersion degree and the same-row fluctuation difference value;

[0034] The proportional coefficient adjustment value is positively correlated with the water and fertilizer flow deviation, and negatively correlated with the fusion result.

[0035] In one embodiment, the expression of the proportional coefficient adjustment value is:

[0036] Where, P i,j,t Represents the i-th row and j-th column tree W i,j The proportional coefficient adjustment value at the tth acquisition moment; F i,j,t 、y i,j,t 、C i,j,t Represents the tree W i,j The water and fertilizer flow deviation at the tth collection moment, the pressure dispersion degree, and the same-row fluctuation difference value; P1 and P2 both represent constants preset to be greater than 0; β is a value preset to be greater than 0; norm() is a normalization function.

[0037] In one embodiment, the process of determining the proportional term parameter of the PID control algorithm to control the fertilizer flow rate of each tree is as follows:

[0038] The proportional coefficient adjustment value is used as the proportional term parameter of the PID control algorithm in the PID controller of each tree at each collection time. The PID controller is used to control the opening of the electric valve at the fertilizer nozzle of each tree, and the fertilizer flow of each tree is controlled by the opening.

[0039] In the second aspect, an embodiment of the present application also provides a precise control system for the fertilizer flow of an integrated water-fertilizer machine for economic forest tree species, comprising a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of any one of the above-mentioned methods for precisely controlling the fertilizer flow of an integrated water-fertilizer machine for economic forest tree species are implemented.

[0040] This application has at least the following beneficial effects:

[0041] This application analyzes the fluctuation characteristics of the water and fertilizer flow in the water-fertilizer mixing pipe at the fertilizer nozzle of each tree, and combines the influence of the water and fertilizer flow upstream of the water-fertilizer mixing pipe on the water and fertilizer flow downstream to determine the fluctuation trend influence coefficient and the upstream trend influence coefficient. Then, the water and fertilizer flow deviation is obtained. This can more accurately assess the degree to which the water and fertilizer flow in the water-fertilizer mixing pipe at the fertilizer nozzle of each tree deviates from the preset water and fertilizer flow, so that when the fertilizer flow of the tree is subsequently controlled, the fertilizer flow deviation can be responded to more quickly.

[0042] Furthermore, by analyzing the similarity of water pressure in the water-fertilizer mixing pipe at the fertilization nozzles of the same row of trees in the planting field, as well as the impact of the opening of the electric valve on the water pressure, the fluctuation difference value in the same row is determined. This can more accurately assess whether the fluctuation of water pressure is caused by the opening adjustment of the electric valve. In the subsequent control process of the fertilizer flow, the impact of the water pressure fluctuation caused by the opening adjustment of the electric valve on the fluctuation of the water and fertilizer flow can be reduced, thereby improving the control accuracy of the fertilizer flow to the trees.

[0043] Furthermore, a proportional coefficient adjustment value is determined, and a proportional term parameter in a PID control algorithm in a PID controller is adaptively adjusted according to the proportional coefficient adjustment value. The PID controller is used to adjust the opening of the electric valve at the fertilizer nozzle. The fertilizer flow rate of each tree is controlled by the opening, which can better adapt to the flow characteristics of water and fertilizer in the water-fertilizer mixing pipe at the fertilizer nozzle of each tree, thereby improving the control accuracy of the fertilizer flow rate of each tree. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0045] Figure 1 This is a flowchart of a method for accurately controlling the fertilization flow rate of an integrated water and fertilizer machine for economic forest tree species provided in one embodiment of the present application;

[0046] Figure 2 This is a schematic diagram of the fertilization scene of the water and fertilizer integrated machine;

[0047] Figure 3 Schematic diagram of the process of obtaining the fluctuation trend influence coefficient. DETAILED DESCRIPTION

[0048] In the description of the embodiments of this application, words such as "exemplary," "or," and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "or," and "for example" is intended to present the relevant concepts in a concrete manner.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application relates. The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. It should be understood that, unless otherwise indicated, " / " represents or.

[0050] It should also be noted that the terms "first" and "second" in this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0051] The following describes in detail the specific scheme of the method and system for accurately controlling the fertilization flow of an integrated water and fertilizer machine for economic forest tree species provided by this application in conjunction with the accompanying drawings.

[0052] See also Figure 1 , which shows a flowchart of a method for accurately controlling the fertilization flow rate of an integrated water and fertilizer machine for economic forest tree species provided by an embodiment of the present application, the method comprising the following steps:

[0053] Step 1: Collect the water and fertilizer pressure data and water and fertilizer flow data in the water and fertilizer mixing pipe in real time at the fertilizer nozzle of each tree.

[0054] Taking the planting field of any economic forest tree species as an example, at the fertilizer nozzle of each tree, pressure sensors and liquid flow sensors are used to collect water and fertilizer pressure data and water and fertilizer flow data in the water and fertilizer mixing pipeline in real time, and recorded as water and fertilizer pressure data and water and fertilizer flow data of each tree. Pressure sensors and liquid flow sensors are also used to collect water and fertilizer pressure data and water and fertilizer flow data in the water and fertilizer mixing main pipeline in real time. The schematic diagram of the fertilization scene of the water and fertilizer integrated machine is as follows: Figure 2 As shown, Figure 2 1 represents the pool, 2 represents the filter tank, 3 represents the water and fertilizer integrated machine, 4 represents the fertilizer tank, 5 represents the electric valve, 6 represents the water and fertilizer mixing main pipeline, 7 represents the fertilizer nozzle with an electric valve, 8 represents the water and fertilizer mixing pipeline, Figure 2 The row of trees parallel to the main water-fertilizer mixing pipe is the same row of trees, and the row of trees perpendicular to the main water-fertilizer mixing pipe is the same column of trees.

[0055] In this embodiment, when collecting water and fertilizer pressure data and water and fertilizer flow data, the sampling frequency is 20 Hz. The value of the sampling frequency is preset manually and can be set by the implementer. This application does not impose any special restrictions.

[0056] During fertilization of trees in a field, taking the tth collection moment as an example, water and fertilizer pressure data and water and fertilizer flow data are obtained for each tree within a preset time interval prior to the tth collection moment. Furthermore, water and fertilizer pressure data and water and fertilizer flow data are obtained for the water and fertilizer mixing main pipeline within the preset time interval prior to the tth collection moment. The preset time interval is adjacent to the tth collection moment. Furthermore, a preset water and fertilizer flow value required for each tree is obtained. This preset water and fertilizer flow value is determined based on the tree's growth environment and species.

[0057] In this embodiment, the length of the preset time interval is 2 seconds. The value of the length of the preset time interval is preset manually and can be set by the implementer. This application does not impose any special restrictions.

[0058] In order to avoid the impact of data dimension on subsequent data processing, all water and fertilizer pressure data, water and fertilizer flow data, and preset water and fertilizer flow values ​​obtained are normalized respectively, and all water and fertilizer pressure data and all water and fertilizer flow data of each tree after normalization are arranged in time series to form the water and fertilizer pressure sequence and water and fertilizer flow sequence of each tree at the tth collection time; all water and fertilizer pressure data and all water and fertilizer flow data in the water and fertilizer mixing main pipeline after normalization are arranged in time series to form the water and fertilizer pressure sequence and water and fertilizer flow sequence of the water and fertilizer mixing main pipeline at the tth collection time.

[0059] In this embodiment, the Min-Max normalization method is used to normalize the water and fertilizer pressure data, water and fertilizer flow data, and preset water and fertilizer flow values. As other implementation methods, on the basis of being able to normalize the water and fertilizer pressure data, water and fertilizer flow data, and preset water and fertilizer flow values, the implementer can adopt other existing technologies, such as decimal calibration normalization method, Sigmoid function, etc., and this application does not impose any special restrictions.

[0060] Step 2: within a preset time interval before each collection moment, comprehensively analyze the water and fertilizer flow data and water and fertilizer pressure data in the water and fertilizer mixing pipe to determine the proportional coefficient adjustment value of each tree at each collection moment.

[0061] When using a PID controller to control the fertilizer flow of a tree fertilizer nozzle, the greater the deviation of the actual water and fertilizer flow value in the water and fertilizer mixing pipe at the tree fertilizer nozzle from the preset water and fertilizer flow value, the greater the degree of adjustment of the opening of the electric valve at the fertilizer nozzle needs to be. Therefore, it is necessary to adjust the proportional term parameters in the PID controller to increase the response speed of the electric valve to the fertilizer flow error, and then adjust the fertilizer flow of the fertilizer nozzle in time.

[0062] Step 2.1: Analyze the fluctuation of water and fertilizer flow data for each tree within a preset time period before each collection moment, and determine the fluctuation trend influence coefficient of each tree at each collection moment.

[0063] During the fertilization process for trees in a plantation, chemical deposits may form due to chemical reactions between the alkalinity of the water source and the fertilizer. These deposits can settle in the pipes, causing blockages. Alternatively, rust may form due to corrosion, blocking the pipes and affecting the flow of water and fertilizer. Alternatively, impurities in the water source may not be completely filtered, hindering the flow of liquid in the water-fertilizer mixing pipes, causing the water flow in the mixing pipes to fluctuate. When the water flow fluctuation in the mixing pipes increases, the water flow fluctuations lead to unstable water flow. The unstable water flow hinders the flow in the pipes, resulting in a decrease in water flow.

[0064] Based on the above analysis, the tree W in the i-th row and j-th column in the planting field is i,j For example, for tree W i,j The water and fertilizer flow sequence A at the tth collection time i,j,t , calculate the water and fertilizer flow sequence A i,j,t The discrete degree of each consecutive adjacent preset number of data is recorded as the flow discrete degree, and the tree W i,j All the traffic discrete degrees corresponding to the t-th collection time are arranged in time sequence to form a tree W i,j The discrete sequence of traffic at the tth acquisition moment. The discrete sequence of traffic is used to characterize the tree W i,jThe fluctuation of the water and fertilizer flow in the water and fertilizer mixing pipe at the fertilization nozzle during the historical time period at the tth collection moment.

[0065] In this embodiment, the value of the preset number is 5. The value of the preset number is preset by humans and can be set by the implementer. This application does not impose any special restrictions. i,j,t Each data point in the window is the first element. A window of size 1×5 is constructed and the degree of dispersion of the five data points in each window is calculated. If there is insufficient data in a window, no calculation is performed.

[0066] In this embodiment, the degree of dispersion is the standard deviation. As other implementation methods, on the basis of being able to measure the uneven distribution of the preset number of data, the implementer may use other existing technologies for measurement, such as variance, coefficient of variation, etc., and no special restrictions are imposed on the application.

[0067] Obtain a fitting straight line for all data in the flow discrete sequence, use the slope of the fitting straight line as the exponent of an exponential function with a natural constant as the base, and use the calculation result of the exponential function as the tree W i,j The fluctuation trend influence coefficient at the tth sampling moment. The purpose of the exponential function is to map all slopes to positive numbers.

[0068] In this embodiment, the least squares method is used to obtain the fitting straight line. The least squares method is a well-known technology and will not be described in detail in this application. As other implementation methods, on the basis of obtaining the fitting straight line of all data in the discrete flow sequence, the implementer can use other existing technologies to obtain the fitting straight line, such as linear regression analysis, weighted least squares method, etc. This application does not impose any special restrictions.

[0069] It should be noted that the fluctuation trend influence coefficient is used to evaluate the i,j The influence of water flow fluctuation in the water-fertilizer mixing pipe on the water and fertilizer flow at the fertilization nozzle is as follows: In the historical time period at the t-th collection moment, if the water flow fluctuation has an increasing trend, that is, the calculation result of the exponential function is larger, the water flow is hindered more when flowing in the pipe, and the water and fertilizer flow is more likely to show a downward trend at the t-th collection moment, that is, the greater the fluctuation trend influence coefficient. The flow chart of obtaining the fluctuation trend influence coefficient is as follows: Figure 3 shown.

[0070] Step 2.2: Obtain the trees upstream of the water-fertilizer mixing pipeline at the location of each tree, analyze the distance between each tree and its upstream trees, and the changes in the water-fertilizer flow data of each upstream tree within a preset time period before each collection time, and determine the upstream trend influence coefficient of each tree at each collection time.

[0071] Secondly, when fertilizing trees in the same row in a planting field, the water-fertilizer mixing pipes used by the trees in the same row are usually connected, so the water and fertilizer flow at a certain point in the water-fertilizer mixing pipe is usually affected by the change in the water and fertilizer flow in the upstream pipe.

[0072] Based on the above analysis, we still take tree W as an example. i,j For example, all trees with row number less than i and column number equal to j in the planting field are considered to be in tree W. i,j The tree is located upstream of the water-fertilizer mixing pipe.

[0073] In the tree W i,j Upstream tree W i-1,j For example, for tree W i-1,j In the water and fertilizer flow sequence at the t-th collection moment, a fitting straight line for all data in the water and fertilizer flow sequence is obtained, which is recorded as a flow fitting straight line. Wherein, if i is 1, the flow fitting straight line is obtained for the water and fertilizer flow sequence of the water and fertilizer mixing main pipeline.

[0074] Furthermore, the distance between each tree and its upstream trees, as well as the slope of the flow fitting line of each upstream tree, are analyzed to determine the upstream trend influence coefficient of each tree at each sampling time. This is used to characterize the influence of the changing trend of the water and fertilizer flow in the water and fertilizer mixing pipe on the water and fertilizer flow at the fertilizer nozzle of each tree. The expression is:

[0075] Where, Represents the i-th row and j-th column tree W i,j The upstream trend influence coefficient at the tth collection time; i represents the tree W i,j The number of rows; norm() represents the normalization function; d g,i Representation tree W i,j The number of rows and tree W g,j The reciprocal of the difference in the number of rows; exp() represents an exponential function with a natural constant as the base; k g,j,t It represents the slope of the flow fitting line of the tree in the g-th row and j-th column.

[0076] In this embodiment, the Softmax function is used to g,i Normalization is performed, as another embodiment, in which d g,i On the basis of normalization processing, the implementer may adopt other existing technologies, such as decimal calibration normalization method, Sigmoid function, etc., and this application does not impose any special restrictions.

[0077] It should be noted that: in the historical time period of the tth collection moment, in the tree W g,j The greater the fertilization nozzle, the greater the possibility that the water and fertilizer flow in the water and fertilizer mixing pipe will increase, that is, exp(kg,j,t ) is larger, and the tree W g,j With Tree W i,j The smaller the distance between them, that is, norm(d g,i ) is larger, the larger the tree W i,j At the fertilization nozzle, the water and fertilizer flow in the water and fertilizer mixing pipe is more likely to increase at the tth sampling time, that is, the upstream trend influence coefficient The bigger.

[0078] Step 2.3: Analyze the distribution of water and fertilizer flow data for each tree within a preset time period before each collection moment, and determine the water and fertilizer flow deviation of each tree at each collection moment by combining the fluctuation trend influence coefficient, the upstream trend influence coefficient, and the preset water and fertilizer flow value required for each tree.

[0079] Furthermore, the distribution of the water and fertilizer flow data in each tree at each collection moment is analyzed, and the water and fertilizer flow deviation of each tree at each collection moment is determined by combining the fluctuation trend influence coefficient, the upstream trend influence coefficient, and the preset water and fertilizer flow value. This is used to characterize the degree to which the water and fertilizer flow in the water and fertilizer mixing pipe at the fertilizer nozzle of each tree deviates from the preset water and fertilizer flow. The expression is:

[0080] Where, F i,j,t Represents the i-th row and j-th column tree W i,j The deviation of water and fertilizer flow at the tth collection moment; Representation tree W i,j The mean of all data in the water and fertilizer flow series at the tth collection moment; Represents the tree W i,j Fluctuation trend influence coefficient and upstream trend influence coefficient at the tth collection moment; a i,j Representation tree W i,j The preset water and fertilizer flow value. Denoted as tree W i,j The actual water and fertilizer flow value at the tth collection moment.

[0081] It should be noted that: in the historical time period of the tth collection moment, in the tree W i,j At the fertilizer nozzle, the water flow fluctuation in the water-fertilizer mixing pipe tends to increase. The larger the tree W i,j The water and fertilizer flow in the upstream water and fertilizer mixing pipe has a downward trend at the tth sampling time. i,j At the fertilization nozzle, the smaller the water and fertilizer flow in the water and fertilizer mixing pipe is at the tth collection time, that is, The smaller the tree W i,jThe greater the difference between the actual water and fertilizer flow value at the tth sampling moment and the preset water and fertilizer flow value, the greater the difference between the actual water and fertilizer flow value at the tth sampling moment and the preset water and fertilizer flow value. i,j At the fertilizer nozzle, the more the water and fertilizer flow in the water and fertilizer mixing pipe deviates from the preset water and fertilizer flow value at the tth collection moment, that is, the greater the water and fertilizer flow deviation value.

[0082] Step 2.4: Analyze the difference in the degree of dispersion of water and fertilizer pressure data between each tree and the trees in the same row within a preset time period before each collection moment, and determine the fluctuation difference value of each tree in the same row at each collection moment.

[0083] Since the water pump is the power source of the integrated water and fertilizer unit, responsible for transporting the water and fertilizer mixture throughout the irrigation system, when using the integrated water and fertilizer unit for commercial forest species to fertilize trees in a field, the water pressure in the water-fertilizer mixing pipe at each tree's fertilization nozzle is primarily related to the length of the pipe from the pump to the pipe. Therefore, the water pressure in the pipe at the fertilization nozzles of trees in the same row of the field is generally similar. However, when adjusting the opening of the electric valve to control the water and fertilizer flow in the pipe, water pressure fluctuations in the pipe are often caused. The wider the opening range of the electric valve, the greater the water pressure fluctuations, which will cause subsequent fluctuations in the water and fertilizer flow in the pipe. Therefore, to improve the stability of the water pressure in the pipe and reduce the impact of water pressure fluctuations caused by electric valve opening adjustment on subsequent water and fertilizer flow fluctuations, it is necessary to reduce the proportional coefficient of the PID controller when controlling the electric valve opening.

[0084] Based on the above analysis, we still take tree W as an example. i,j For example, the computation tree W i,j The discrete degree of all data in the water and fertilizer pressure series at the tth collection moment is recorded as the pressure discrete degree; the tree W i,j The difference in the degree of pressure dispersion between the trees in the same row is recorded as the dispersion difference; the mean of all the obtained dispersion differences is taken as the tree W i,j The fluctuation difference value of the same row at the tth collection time.

[0085] In this embodiment, the degree of dispersion of all data in the water and fertilizer pressure sequence is the standard deviation. As other implementation methods, on the basis of being able to measure the degree of uneven distribution of all data in the water and fertilizer pressure sequence, the implementer can adopt other existing technologies, such as variance, coefficient of variation, etc., and this application does not impose any special restrictions.

[0086] It should be noted that: in the historical time period of the tth collection moment, in the tree W i,jThe greater the difference in the water pressure fluctuation in the water-fertilizer mixing pipe at the fertilizer nozzle of the trees in the same row, that is, the greater the fluctuation difference in the same row, the greater the fluctuation in the water pressure in the tree W. i,j The reason for the water pressure fluctuation in the water-fertilizer mixing pipe at the fertilization nozzle is more likely to be: in the historical time period of the tth collection moment, the tree W i,j This is caused by the opening adjustment of the electric valve at the fertilizer nozzle.

[0087] Step 2.5: Comprehensively analyze the water and fertilizer flow deviation, the same-row fluctuation difference, and the discrete degree of each tree to determine the proportional coefficient adjustment value of each tree at each collection time.

[0088] Furthermore, the water and fertilizer flow deviation and the same-row fluctuation difference, as well as the pressure dispersion of each tree, are comprehensively analyzed to determine the proportional coefficient adjustment value of each tree at each sampling time. This is used to characterize the value of the proportional term parameter of the PID control algorithm at each sampling time when the PID controller is used to adjust the opening of the electric valve at the fertilizer nozzle of each tree. The expression is:

[0089] Where, P i,j,t Represents the i-th row and j-th column tree W i,j The proportional coefficient adjustment value at the tth acquisition moment; F i,j,t 、y i,j,t 、C i,j,t Represents the tree W i,j At the t-th collection moment, the water and fertilizer flow deviation, the pressure dispersion, and the same-row fluctuation difference value; P1 and P2 both represent constants greater than 0. When P is satisfied i,j,t The value range of is (0,1), and the values ​​of P1 and P2 can be set by the implementer. β is a preset value greater than 0, the purpose of which is to prevent the denominator from being 0. The value of β can be set by the implementer. In this embodiment, the value of β is 0.01. norm() is a normalization function.

[0090] In this embodiment, to avoid the proportional term parameter being too large, which will cause unstable water and fertilizer flow rates, and to avoid the proportional term parameter being too small, which will cause the PID controller to respond too slowly to the water and fertilizer flow rate error, the values ​​of P1 and P2 are 0.6 and 0.3 respectively.

[0091] In this embodiment, the Min-Max normalization method is used to Normalization is performed, as another implementation method, in which On the basis of normalization processing, the implementer may adopt other existing technologies, such as decimal calibration normalization method, Sigmoid function, etc., and this application does not impose any special restrictions.

[0092] It should be noted that: in the tree Wi,j At the fertilization nozzle, the more the water and fertilizer flow in the water and fertilizer mixing pipe deviates from the preset water and fertilizer flow value at the tth collection time, that is, the greater the value of the water and fertilizer flow deviation, the more effective it is to improve the tree W i,j The response speed of the electric valve at the fertilizer nozzle to the fertilizer flow error is adjusted in time. i,j The larger the actual fertilizer flow rate, the larger the proportional term parameter of the PID control algorithm should be, that is, P i,j,t The larger the value, the greater the historical period of the tree W in the tth collection moment. i,j The greater the water pressure fluctuation in the water-fertilizer mixing pipe at the fertilization nozzle, the greater the i,j,t The larger it is, the more likely it is due to tree W i,j Corresponding to the opening adjustment of the electric valve, that is, C i,j,t The larger the tree W is, the better. i,j The stability of the water pressure in the water-fertilizer mixing pipeline at the location is used to reduce the impact of water pressure fluctuations caused by electric valve opening adjustment on subsequent water and fertilizer flow fluctuations. The proportional term parameter of the PID controller algorithm should be smaller, that is, P i,j,t The smaller.

[0093] Follow the tree with W i,j The proportional coefficient adjustment value at the t-th collection moment is obtained using the same acquisition method, and the proportional coefficient adjustment value of each tree at each collection moment is obtained.

[0094] Step 3: Based on the proportional coefficient adjustment value, determine the proportional term parameter of the PID control algorithm to control the fertilizer flow rate of each tree.

[0095] Each tree's fertilizer nozzle has a controller that controls the valve's opening. The proportional coefficient adjustment value for each tree at each data collection moment serves as the proportional term parameter of the PID control algorithm in each tree's PID controller at that time. The PID controller controls the opening of the valve at each tree's fertilizer nozzle, thereby controlling the fertilizer flow rate to each tree. During fertilizer flow control for trees in the field, if insufficient data exists to calculate the proportional term parameter of the PID control algorithm, calculation is omitted.

[0096] Based on the same inventive concept as the above method, an embodiment of the present application also provides a precise control system for the fertilizer flow of an integrated water-fertilizer machine for economic forest tree species, comprising a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above-mentioned methods for precise control of the fertilizer flow of an integrated water-fertilizer machine for economic forest tree species.

[0097] In summary, this application analyzes the fluctuation characteristics of the water and fertilizer flow in the water-fertilizer mixing pipe at the fertilizer nozzle of each tree, and combines the influence of the water and fertilizer flow upstream of the water-fertilizer mixing pipe on the downstream water and fertilizer flow to determine the fluctuation trend influence coefficient and the upstream trend influence coefficient, thereby obtaining the water and fertilizer flow deviation. This can more accurately assess the degree to which the water and fertilizer flow in the water-fertilizer mixing pipe at the fertilizer nozzle of each tree deviates from the preset water and fertilizer flow, so that when subsequently controlling the tree's fertilizer flow, it can respond more quickly to the fertilizer flow deviation;

[0098] Furthermore, by analyzing the similarity of water pressure in the water-fertilizer mixing pipe at the fertilization nozzles of the same row of trees in the planting field, as well as the impact of the opening of the electric valve on the water pressure, the fluctuation difference value in the same row is determined. This can more accurately assess whether the fluctuation of water pressure is caused by the opening adjustment of the electric valve. In the subsequent control process of the fertilizer flow, the impact of the water pressure fluctuation caused by the opening adjustment of the electric valve on the fluctuation of the water and fertilizer flow can be reduced, thereby improving the control accuracy of the fertilizer flow to the trees.

[0099] Furthermore, a proportional coefficient adjustment value is determined, and a proportional term parameter in a PID control algorithm in a PID controller is adaptively adjusted according to the proportional coefficient adjustment value. The PID controller is used to adjust the opening of the electric valve at the fertilizer nozzle. The fertilizer flow rate of each tree is controlled by the opening, which can better adapt to the flow characteristics of water and fertilizer in the water-fertilizer mixing pipe at the fertilizer nozzle of each tree, thereby improving the control accuracy of the fertilizer flow rate of each tree.

[0100] The flowcharts and block diagrams in the accompanying drawings show the possible implementation architectures, functions and operations of the systems, methods and computer program products according to the embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, program segment or part of the code, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical functions. In some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, or they can sometimes be executed in the opposite order, which can depend on the functions involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different boxes can also occur in an order different from that disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed substantially in parallel, or they can sometimes be executed in the opposite order, which can depend on the functions involved. Each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a dedicated hardware-based system that performs the specified function or action, or may be implemented by a combination of dedicated hardware and computer instructions.

[0101] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the basic characteristics of the present application. Therefore, from all perspectives, the above embodiments of the present application should be regarded as exemplary and non-restrictive.

Claims

1. A method for accurately controlling the fertilization flow rate of an integrated water and fertilizer machine for economic forest tree species, characterized in that: The method comprises the following steps: At the fertilizer nozzle of each tree, the water and fertilizer pressure data and water and fertilizer flow data in the water and fertilizer mixing pipe are collected in real time and recorded as the water and fertilizer pressure data and water and fertilizer flow data of each tree; Analyze the fluctuation of water and fertilizer flow data for each tree within a preset period of time before each collection time, and determine the fluctuation trend influence coefficient of each tree at each collection time; Obtain the trees upstream of the water and fertilizer mixing pipeline at each tree's location, analyze the distance between each tree and its upstream trees, and the changes in water and fertilizer flow data of each upstream tree within a preset period before each collection time, and determine the upstream trend influence coefficient of each tree at each collection time; Analyze the distribution of water and fertilizer flow data for each tree within a preset time period before each collection moment, and determine the water and fertilizer flow deviation of each tree at each collection moment by combining the fluctuation trend influence coefficient, the upstream trend influence coefficient, and the preset water and fertilizer flow value required for each tree; Analyze the differences in the degree of dispersion of water and fertilizer pressure data between each tree and the trees in the same row within a preset period before each collection time, and determine the fluctuation difference value of each tree in the same row at each collection time; Comprehensively analyzing the water and fertilizer flow deviation and the same-row fluctuation difference, as well as the discreteness of each tree, to determine the proportional coefficient adjustment value of each tree at each collection moment; Based on the proportional coefficient adjustment value, the proportional term parameter of the PID control algorithm is determined to control the fertilizer flow rate of each tree.

2. The method for accurately controlling the fertilization flow rate of an integrated water and fertilizer machine for economic forest tree species according to claim 1, characterized in that: The process of determining the fluctuation trend influence coefficient is as follows: Arrange the water and fertilizer flow data of each tree within a preset time period before each collection moment in chronological order to form a water and fertilizer flow sequence for each tree at each collection moment; The discrete degree of each preset number of consecutive adjacent data in each water and fertilizer flow sequence is recorded as the flow discrete degree; Arrange all the flow discreteness corresponding to each tree at each collection time in time sequence to form a flow discreteness sequence of each tree at each collection time, and obtain a fitting straight line for all data in each flow discreteness sequence; The fluctuation trend influence coefficient is positively correlated with the slope of the fitting straight line.

3. The method for accurately controlling the fertilization flow rate of an integrated water and fertilizer machine for economic forest tree species according to claim 2, characterized in that: The process of determining the upstream trend influence coefficient is as follows: Obtain the fitting straight line of all data in the water and fertilizer flow series of each upstream tree for each tree, and record it as the flow fitting straight line; The upstream trend influence coefficient is positively correlated with the slope of the flow fitting straight line and negatively correlated with the distance.

4. The method for accurately controlling the fertilization flow rate of an integrated water and fertilizer machine for economic forest tree species according to claim 2, characterized in that: The process of determining the water and fertilizer flow deviation is as follows: Calculate the mean of all data in each water and fertilizer flow series; Determine the actual water and fertilizer flow value of each tree at each collection time by combining the mean, the upstream trend influence coefficient, and the fluctuation trend influence coefficient; The water and fertilizer flow deviation is the difference between the actual water and fertilizer flow value and the preset water and fertilizer flow value.

5. The method for accurately controlling the fertilization flow rate of an integrated water and fertilizer machine for economic forest tree species according to claim 4, characterized in that: The actual water and fertilizer flow rate value is determined as follows: Calculating a ratio of the upstream trend influence coefficient to the fluctuation trend influence coefficient; The actual water and fertilizer flow value is the product of the mean value and the ratio.

6. The method for accurately controlling the fertilization flow rate of an integrated water and fertilizer machine for economic forest tree species according to claim 1, characterized in that: The process of determining the same-row fluctuation difference value is as follows: The dispersion degree of water and fertilizer pressure data of each tree within the preset time period before each collection moment is recorded as pressure dispersion degree; The difference in the degree of pressure dispersion between each tree and the trees in the same row is recorded as dispersion difference; The same-row fluctuation difference value is the mean of all the discrete differences corresponding to each tree.

7. The method for accurately controlling the fertilization flow rate of an integrated water and fertilizer machine for economic forest tree species according to claim 6, characterized in that: The process of determining the proportional coefficient adjustment value is as follows: Calculating a fusion result of the pressure dispersion degree and the same-row fluctuation difference value; The proportional coefficient adjustment value is positively correlated with the water and fertilizer flow deviation, and negatively correlated with the fusion result.

8. The method for accurately controlling the fertilization flow rate of an integrated water and fertilizer machine for economic forest tree species according to claim 6, characterized in that: The expression of the proportional coefficient adjustment value is: Where, P i,j,t Represents the i-th row and j-th column tree W i,j The proportional coefficient adjustment value at the tth acquisition moment; F i,j,t 、y i,j,t 、C i,j,t Represents the tree W i,j The water and fertilizer flow deviation at the tth collection moment, the pressure dispersion degree, and the same-row fluctuation difference value; P1 and P2 both represent constants preset to be greater than 0; β is a value preset to be greater than 0; norm() is a normalization function.

9. The method for accurately controlling the fertilization flow rate of an integrated water and fertilizer machine for economic forest tree species according to claim 1, characterized in that: The process of determining the proportional term parameters of the PID control algorithm to control the fertilizer flow rate of each tree is as follows: The proportional coefficient adjustment value is used as the proportional term parameter of the PID control algorithm in the PID controller of each tree at each collection time. The PID controller is used to control the opening of the electric valve at the fertilizer nozzle of each tree, and the fertilizer flow of each tree is controlled by the opening.

10. A precise control system for fertilizer flow rate of an integrated water and fertilizer machine for economic forest tree species, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the method for accurately controlling the fertilization flow of an integrated water and fertilizer machine for economic forest tree species as described in any one of claims 1 to 9 are implemented.

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