Granular fertilizer flow sensor, fertilizer discharge detection method and variable fertilization system

Abstract

This invention discloses a granular fertilizer flow sensor, a fertilizer discharge detection method, and a dual-closed-loop variable fertilization system. The sensor comprises a housing, a turbine guide mechanism, an optical path adjustment lens group, a laser emitting module, and a photoelectric sensing circuit. The sensor is installed between the fertilizer discharge port of the fertilizer dispenser and the fertilizer discharge pipe. Fertilizer entering the sensor from the turbine guide mechanism is uniformly dispersed. The light emitted by the laser emitting module is first collimated by the optical path adjustment lens group before passing through the fertilizer. The remaining light, after being blocked by the fertilizer, is focused by the optical path adjustment lens group. The photoelectric sensing circuit outputs a processed voltage signal. The dual-closed-loop variable fertilization control system consists of two closed-loop feedback loops for flow rate and rotational speed. The fertilization system of this invention features high detection accuracy, good dustproof performance, and convenient assembly and disassembly.

Description

Technical Field

[0001] This invention belongs to the field of agricultural sensor technology, and relates to a granular fertilizer flow sensor, a fertilizer discharge detection method, and a variable fertilization system, particularly to a granular fertilizer flow sensor, a fertilizer discharge detection method, and a dual closed-loop variable fertilization system based on the infrared photoelectric effect. Background Technology

[0002] The use of chemical fertilizers to increase agricultural yields is very common. However, excessive application of chemical fertilizers not only fails to effectively improve food production capacity, but also causes soil compaction, leading to a decline in land productivity and damaging the agricultural environment. Residual fertilizers in the soil can also be washed into rivers by rainwater, causing eutrophication and resulting in agricultural non-point source pollution. Therefore, scientifically and effectively reducing the use of chemical fertilizers is increasingly becoming a consensus.

[0003] Variable-rate fertilization technology is an important component of precision agriculture and an inevitable trend in modern agricultural development. As a crucial feedback link in variable-rate fertilization control systems, the accuracy of fertilizer application rate detection is a key factor in achieving precise fertilizer application control. In my country, agricultural fertilizers are mainly granular fertilizers. Existing methods for detecting granular fertilizer discharge rates, such as detecting discharge shaft speed, motor speed, or discharge port opening, are mostly indirect measurements of granular fertilizer flow rate. These methods lack high accuracy, are susceptible to interference, and lack direct detection devices for granular fertilizer flow rate.

[0004] Purpose of the invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a granular fertilizer flow sensor and a fertilizer discharge detection method based on the infrared photoelectric effect. This method can detect fertilizer discharge flow in real time and accurately, with a fast response speed, small size, and convenient installation, thus meeting the requirements of field operations. Summary of the Invention

[0006] According to one aspect of the present invention, a granular fertilizer flow sensor based on the infrared photoelectric effect is provided. The granular fertilizer flow sensor comprises a housing (Ⅰ), a turbine guide mechanism (Ⅱ), an optical path adjustment lens group (Ⅲ), a laser emitting module (Ⅳ), and a photoelectric sensing circuit (Ⅴ). The housing (Ⅰ) consists of a left housing (103), a right housing (104), and a PVC dust cover (105). The left housing (103) and the right housing (104) are fitted together via a slot. The dust cover (105) is attached to the inner windows of the left housing (103) and the right housing (104) respectively; the turbine guide mechanism (II) is composed of turbine blades (110) and turbine shaft (111), and the upper crossbeam of the turbine shaft (111) is fixed at the openings on the left housing (103) and the right housing (104); the optical path adjustment lens group (III) is composed of Fresnel collimating lens (106) and Fresnel condensing lens (102), and the Fresnel collimating lens (106) is fixed In the right housing (104), the Fresnel focusing lens (102) is fixed in the left housing (103); the laser emitting module (Ⅳ) consists of a linear laser emitter (109), a heat sink copper plate (108), and an internal hexagon set screw (107); the linear laser emitter (109) mates with the hole wall of the heat sink copper plate (108), and is fixed at the focal point of the Fresnel collimating lens (106) by the internal hexagon set screw (107); the photoelectric sensing circuit (V) is composed of an infrared phototransistor (112), a precision resistor (113), a pre-low-pass filter (114), an analog-to-digital converter integrated circuit (115), a DSP digital signal processing module (116), and a CAN communication module (117); the position of the infrared phototransistor (112) coincides with the Fresnel focusing lens (102); the photoelectric sensing circuit (V) is arranged on a circular PCB circuit board (101) and is attached to the upper slot of the left shell (103);

[0007] The infrared phototransistor (112), Fresnel condenser lens (102), Fresnel collimating lens (106), and line laser emitter (109) are arranged on a coaxial line; the line laser emitter (109) and infrared phototransistor (112) are respectively located at the focal points of the Fresnel collimating lens (106) and the Fresnel condenser lens (102);

[0008] The precision resistor (113) is connected to the collector of the infrared phototransistor (112); the pre-low-pass filter (114) is connected in series with the analog-to-digital converter integrated circuit (115) and then in parallel with the collector of the precision resistor (113) and the infrared phototransistor (112);

[0009] Preferably, the granular fertilizer flow sensor is installed between the fertilizer discharge port of the fertilizer dispenser and the fertilizer discharge pipe. After the left shell (103) and the right shell (104) are glued together by the groove, the upper end of the outer shell (Ⅰ) is connected to the fertilizer discharge port of the fertilizer dispenser, and the lower end is connected to the fertilizer discharge pipe.

[0010] According to another aspect of the present invention, a method for detecting fertilizer discharge using the above-described granular fertilizer flow sensor is provided, comprising the following steps:

[0011] Step 1: After the granular fertilizer flow sensor is powered on, the linear laser emitter (109) emits an infrared light source with a projection shape of a horizontal line. The infrared light source is located at the focal point of the Fresnel collimating lens (106). The light path is adjusted to thin-surface parallel light by the Fresnel collimating lens (106) and radiates into the space between the left housing (103) and the right housing (104) of the sensor.

[0012] Step 2: When fertilizer particles flow out from the fertilizer discharge port of the fertilizer dispenser, the fertilizer particles fall into the outer shell (Ⅰ) of the granular fertilizer flow sensor from the lower fertilizer discharge port of the fertilizer dispenser, and impact the turbine blade (110) at a certain speed, causing the turbine blade (110) to rotate. The clusters of fertilizer particles are dispersed under the drive of the turbine blade (110) and are evenly distributed in the outer shell (Ⅰ).

[0013] Step 3: The dispersed fertilizer particles block part of the thin-surface parallel light adjusted by the Fresnel collimating lens (106) between the left shell (103) and the right shell (104). The remaining infrared light source is focused on the infrared phototransistor (112) by the Fresnel focusing lens (102). The precision resistor (113) is connected to the collector of the infrared phototransistor (112) to convert the change in collector current into the change in voltage across the precision resistor (113).

[0014] Step 4: By acquiring the potential difference between the collector of the infrared phototransistor (112) and the precision resistor (113) and the zero reference potential, the change in light intensity is converted into a voltage change signal. The voltage change signal is amplified by the pre-low-pass filter (114) and high-frequency noise signals are filtered out. Then, it is converted into a digital signal by the analog-to-digital converter integrated circuit (115). After digital filtering by the DSP digital signal processing module (116), the flow data is obtained. Finally, the flow data is transmitted to the display and control terminal through the CAN communication module (117).

[0015] According to another aspect of the present invention, a dual closed-loop variable fertilizer application control system based on CAN bus communication using the aforementioned granular fertilizer flow sensor is provided, comprising an integrated display and control terminal, a CAN parsing module, a GNSS positioning module, a CAN communication bus, a fertilizer tank (118) equipped with the granular fertilizer flow sensor, and a multi-channel motor driver. The fertilizer tank (118) has four electrically driven fertilizer discharge units suspended below it, each of which consists of a DC motor (121) with an encoder, an external grooved wheel fertilizer discharger (119), and a granular fertilizer flow sensor (120).

[0016] The integrated display and control terminal determines the target fertilization amount and motor speed based on the input soil fertility information, and sends the speed information to the motor drive through the control system.

[0017] The control process of the dual closed-loop variable fertilization control system includes two feedback loops, namely the feedback from the encoder-equipped DC motor (121) and the granular fertilizer flow sensor (120); wherein, the speed and flow information are fed back to the main control terminal through the CAN communication bus, and the dual closed-loop variable fertilization control system combines the feedback information with the target fertilization amount, and adjusts the speed of the encoder-equipped DC motor (121) through the multi-channel motor driver to realize the variable regulation of the fertilization amount;

[0018] The integrated display and control terminal dynamically displays the flow information fed back by the granular fertilizer flow sensor (120) in each fertilizer discharge unit through a bar chart. It monitors the blockage of the fertilizer discharge pipeline through the flow information in the bar chart and calculates the estimated operation time based on the fed-back flow information. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the flow sensor structure for granular fertilizer.

[0020] Figure 2 Axonometric drawing of turbine guide vane mechanism

[0021] Figure 3 A schematic diagram for adjusting the focusing and collimation of the optical path using a lens group.

[0022] Figure 4 The circuit block diagram of the photoelectric sensing circuit.

[0023] Figure 5 This is a schematic diagram of the overall structure of a granular fertilizer flow sensor installed on a fertilizer tank.

[0024] Figure 6 This is a schematic diagram of the display and control terminal interface.

[0025] Figure 7 This is a schematic diagram of a dual closed-loop variable fertilization control system based on CAN bus communication.

[0026] Figure 8 Flowchart of a single-unit dual-closed-loop variable fertilization control system Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Those skilled in the art will understand that the step numbers used herein are for convenience of description only and are not intended to limit the order in which the steps are performed. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. The terms “comprising” and “including” indicate the presence of the described features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. The term “and / or” refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0029] This invention proposes a granular fertilizer flow sensor based on the infrared photoelectric effect. The granular fertilizer flow sensor is installed between the fertilizer outlet of the fertilizer dispenser and the fertilizer discharge pipe to detect the fertilizer discharge flow at the fertilizer outlet of the fertilizer dispenser.

[0030] Figure 1The diagram shows the structure of a flow sensor for granular fertilizer. As shown in the figure, the granular fertilizer flow sensor based on infrared photoelectric effect consists of an outer shell (Ⅰ), a turbine guide mechanism (Ⅱ), an optical path adjustment lens group (Ⅲ), a laser emission module (Ⅳ), and a photoelectric sensing circuit (Ⅴ). The outer shell (Ⅰ) comprises a left shell (103), a right shell (104), and a PVC dust cover (105). The left shell (103) and right shell (104) are fitted together via a slot, and the PVC dust cover is attached to the inner windows of the left shell (103) and right shell (104), respectively. The turbine guide mechanism (Ⅱ) consists of turbine blades (110) and a turbine shaft (111). The upper beam of the turbine shaft (111) is fixed to the openings on the left shell (103) and right shell (104). The optical path adjustment lens group (Ⅲ) consists of a Fresnel collimating lens (106) and a Fresnel focusing lens (102). The Fresnel collimating lens (106) is fixed to the right shell (104). In the design, the Fresnel focusing lens (102) is fixed in the left housing (103); the laser emitting module (Ⅳ) consists of a line laser emitter (109), a heat sink copper plate (108), and an internal hexagon set screw (107). The line laser emitter (109) is fitted with the hole wall of the heat sink copper plate (108) and fixed at the focal point of the Fresnel collimating lens (106) by the internal hexagon set screw (107); the photoelectric sensing circuit (Ⅴ) consists of an infrared phototransistor (112), a precision resistor (113), a pre-low-pass filter (114), an analog-to-digital converter integrated circuit (115), a DSP digital signal processing module (116), and a CAN communication module (117); the position of the infrared phototransistor (112) coincides with the Fresnel focusing lens (102), and the photoelectric sensing circuit (Ⅴ) is arranged on a circular PCB circuit board (101) and fits into the slot on the left housing (103).

[0031] Figure 2 The turbine guide mechanism (II) is shown in the isometric view. Particle fertilizer falls into the sensor housing from the fertilizer outlet at the bottom of the fertilizer dispenser and impacts the turbine blades (110) at a certain speed, causing the turbine blades (111) to rotate. The clusters of fertilizer particles are dispersed under the action of the blades, reducing the overlap and accumulation of particle clusters, so that the fertilizer is evenly distributed in the housing and improving the accuracy of the detection results.

[0032] Figure 3This is a schematic diagram of the focusing and collimating optical path of the optical path adjustment lens group (Ⅲ) of the granular fertilizer flow sensor. As shown in the figure, the infrared phototransistor (112), Fresnel condenser lens (102), Fresnel collimating lens (106), and line laser emitter (109) are arranged on a coaxial line; the line laser emitter (109) and infrared phototransistor (112) are respectively set at the focal points of Fresnel collimating lens (106) and Fresnel condenser lens (102); the emitted projection shape of the line laser emitter (109) is a thin-surfaced inverted trapezoidal light source with a horizontal line. After passing through Fresnel collimating lens (106), the optical path is adjusted to thin-surfaced parallel light, and then focused by Fresnel condenser lens (102), with the focal point coinciding with the infrared phototransistor (112).

[0033] Figure 4 The circuit diagram shows the photoelectric sensing circuit (V) of the granular fertilizer flow sensor. The precision resistor (113) is connected to the collector of the infrared phototransistor (112). The pre-low-pass filter (114) is connected in series with the analog-to-digital converter (115) and then in parallel with the precision resistor (113) and the collector of the infrared phototransistor (112). The collector current of the infrared phototransistor (112) is linearly related to the light intensity. By collecting the potential difference between the collector of the infrared phototransistor (112) and the precision resistor (113) and the zero reference potential, the change in light intensity is converted into a voltage change. The voltage signal is amplified by the pre-low-pass filter (114) and high-frequency noise signals are filtered out. Then, the analog signal is converted into a digital signal by the analog-to-digital converter (115). After digital filtering by the DSP digital signal processing module (116), stable and accurate flow data is obtained. Finally, the data is transmitted to the display and control terminal through the CAN communication module (117).

[0034] Figure 5 This is a schematic diagram of the overall structure of the granular fertilizer flow sensor installed on the fertilizer tank. Four electrically driven fertilizer discharge units are suspended under the fertilizer tank (118). Each unit consists of a DC motor (121) with an encoder, an outer grooved wheel fertilizer discharger (119), and a granular fertilizer flow sensor (120).

[0035] Figure 6 This is a schematic diagram of the control terminal interface. The bar chart at the bottom dynamically displays the real-time flow information of the four fertilizer application units, while the main display in the middle shows the field topography, the location of agricultural machinery, and soil prescription map information. The mode selection allows switching between manual and automatic adjustment of fertilizer application.

[0036] Figure 7This is a schematic diagram of a dual-closed-loop variable fertilizer application control system based on CAN bus communication. GNSS positioning information, motor drive feedback speed information, and flow information output by the granular fertilizer flow sensor are transmitted to the CAN parsing module via the CAN communication bus. The parsed flow, speed, and position information are input to the display and control terminal, and then the control system combines this with the target fertilizer application rate to achieve dual-closed-loop control of variable fertilizer application.

[0037] Figure 8 This is a flowchart of a single-unit, dual-closed-loop variable fertilization control system. The input to the control system is the target rotational speed v. r The fertilizer discharge unit acts as the actuator. The system first processes the rotational speed v fed back by the motor encoder. c With the target speed v r The deviation is corrected using PID control to obtain the corrected rotational speed v. i The target flow rate q can be obtained from the ratio of rotational speed v to flow rate q = k * v. r , for q r Feedback flow q from the flow sensor c The deviation is corrected again using PID control, and the output q is then adjusted. i As input to the actuator.

[0038] Example 1

[0039] This embodiment is a specific example of using the granular fertilizer flow sensor described in this invention to detect fertilizer discharge volume. The specific operation process includes the following steps:

[0040] Step 1: After the sensor is powered on, an infrared light source with a projection shape of a horizontal line is emitted by the linear laser emitter (109). The light source is located at the focal point of the Fresnel collimating lens (106). The light path is adjusted to thin-surface parallel light by the Fresnel collimating lens (106) and radiates into the space between the left housing (103) and the right housing (104) of the sensor.

[0041] Step 2: When fertilizer particles flow out from the fertilizer discharge port of the fertilizer dispenser, the fertilizer particles fall into the sensor housing from the lower fertilizer discharge port of the fertilizer dispenser and impact the turbine blade (110) at a certain speed, causing the turbine blade (110) to rotate. The clusters of fertilizer particles are dispersed under the action of the turbine blade (110) and evenly distributed in the housing.

[0042] Step 3: The discrete fertilizer particles block part of the thin-plane parallel light adjusted by the Fresnel collimating lens (106) between the left shell (103) and the right shell (104). The remaining light source is focused on the infrared phototransistor (112) by the Fresnel condensing lens (102). The precision resistor (113) is connected to the collector of the infrared phototransistor (112) to convert the change of collector current into the change of voltage across the precision resistor (113).

[0043] Step 4: By acquiring the potential difference between the collector of the infrared phototransistor (112) and the precision resistor (113) and the zero reference potential, the change in light intensity is converted into a voltage change signal. The voltage change signal is amplified by the pre-low-pass filter (114) and high-frequency noise signals are filtered out. Then, it is converted into a digital signal by the analog-to-digital converter integrated circuit (115). After digital filtering by the DSP digital signal processing module (116), the flow data is obtained. Finally, the flow data is transmitted to the display and control terminal through the CAN communication module (117).

[0044] Example 2

[0045] This embodiment describes a dual-closed-loop variable fertilizer application control system based on CAN bus communication, using the aforementioned granular fertilizer flow sensor.

[0046] The dual closed-loop variable fertilization control system based on CAN bus communication in this embodiment includes an integrated display and control terminal, a CAN parsing module, a GNSS positioning module, a CAN communication bus, a fertilizer tank (118) equipped with a granular fertilizer flow sensor, and a multi-channel motor driver. Among them, as shown... Figure 5 As shown, four electrically driven fertilizer discharge units are suspended under the fertilizer box (118). Each unit consists of a DC motor (121) with an encoder, an outer grooved wheel fertilizer discharger (119), and a granular fertilizer flow sensor (120).

[0047] The integrated display and control terminal determines the target fertilization amount and motor speed based on the input soil fertility information, and sends the speed information to the motor drive through the control system.

[0048] The dual closed-loop variable fertilization control system includes two feedback loops: feedback from a DC motor (121) with an encoder and feedback from a granular fertilizer flow sensor (120). The rotation speed and flow rate information are fed back to the main control terminal via a CAN communication bus. The dual closed-loop variable fertilization control system combines the feedback information with the target fertilization amount and adjusts the rotation speed of the DC motor (121) with the encoder through the multi-channel motor driver to achieve variable regulation of the fertilization amount.

[0049] The integrated display and control terminal dynamically displays the flow information fed back by the granular fertilizer flow sensor (120) in each fertilizer discharge unit through a bar chart. It monitors the blockage of the fertilizer discharge pipeline through the flow information in the bar chart and calculates the estimated operation time based on the fed-back flow information.

[0050] The present invention has the following beneficial effects:

[0051] 1) The infrared photoelectric effect granular fertilizer flow sensor of the present invention uses a dust cover and housing to seal the optical path adjustment lens group and photoelectric sensing circuit, protecting the key sensitive components from the pollution of the working environment and ensuring the stability and reliability of the sensor operation.

[0052] 2) The infrared photoelectric effect granular fertilizer flow sensor of the present invention uses a line laser emitter as the light source, which has strong penetration, good dust resistance and high sensitivity.

[0053] 3) The infrared photoelectric effect granular fertilizer flow sensor of the present invention uses a near-infrared laser with a peak wavelength of 940 nanometers and a photosensitive transistor as photoelectric reaction elements, avoiding the visible light band, and is not easily affected by external light sources during operation.

[0054] 4) The infrared photoelectric effect granular fertilizer flow sensor of the present invention uses digital integrated circuits to perform digital filtering processing on the signal. The digital circuit has strong anti-interference ability and the measurement results are less affected by the environment.

[0055] 5) The infrared photoelectric effect granular fertilizer flow sensor of the present invention uses a turbine guide mechanism to disperse the clusters of granular fertilizer, so that the fertilizer is evenly distributed in the sensor housing, reducing the accumulation and overlap of fertilizer and improving the accuracy of the detection results.

[0056] 6) The infrared photoelectric effect granular fertilizer flow sensor of the present invention adds a flow detection link to the variable fertilization control system, providing an effective evaluation index for the accuracy of fertilizer application control and enabling the system to achieve closed-loop control.

[0057] 7) The infrared photoelectric effect granular fertilizer flow sensor of the present invention is simple to install and easy to disassemble. It does not require modification of the fertilizer discharge device and can be directly installed between the fertilizer discharge device and the fertilizer discharge pipe.

Claims

1. A granular fertilizer flow sensor based on infrared photoelectric effect, comprising a housing (Ⅰ), a turbine guide mechanism (Ⅱ), an optical path adjustment lens group (Ⅲ), a laser emitting module (Ⅳ), and a photoelectric sensing circuit (Ⅴ), characterized in that, The outer casing (Ⅰ) consists of a left casing (103), a right casing (104), and a PVC dust cover (105); the left casing (103) and the right casing (104) are fitted together by a slot, and the PVC dust cover (105) is respectively attached to the inner windows of the left casing (103) and the right casing (104); the turbine guide mechanism (Ⅱ) consists of a turbine fan blade (110) and a turbine shaft (111), and the upper end beam of the turbine shaft (111) is fixed at the openings on the left casing (103) and the right casing (104); the optical path adjustment lens group (Ⅲ) consists of a Fresnel collimating lens (106) and a Fresnel condensing lens (102), the Fresnel collimating lens (106) is fixed in the right casing (104), and the Fresnel condensing lens (102) is fixed in the left casing (103); the laser emission Module (Ⅳ) consists of a linear laser emitter (109), a heat sink (108), and a hexagonal set screw (107). The linear laser emitter (109) fits into the hole wall of the heat sink (108) and is fixed at the focal point of the Fresnel collimating lens (106) by the hexagonal set screw (107). The photoelectric sensing circuit (Ⅴ) consists of an infrared phototransistor (112), a precision resistor (113), a pre-low-pass filter (114), an analog-to-digital converter integrated circuit (115), a DSP digital signal processing module (116), and a CAN communication module (117). The position of the infrared phototransistor (112) coincides with that of the Fresnel condenser lens (102). The photoelectric sensing circuit (Ⅴ) is arranged on a circular PCB circuit board (101) and fits against the upper slot of the left housing (103). The infrared phototransistor (112), Fresnel condenser lens (102), Fresnel collimating lens (106), and line laser emitter (109) are arranged on a coaxial line; the line laser emitter (109) and infrared phototransistor (112) are respectively located at the focal points of the Fresnel collimating lens (106) and the Fresnel condenser lens (102); The precision resistor (113) is connected to the collector of the infrared phototransistor (112); the pre-low-pass filter (114) is connected in series with the analog-to-digital converter integrated circuit (115) and then in parallel with the collector of the precision resistor (113) and the infrared phototransistor (112).

2. The granular fertilizer flow sensor based on infrared photoelectric effect according to claim 1, characterized in that, The granular fertilizer flow sensor is installed between the fertilizer discharge port of the fertilizer dispenser and the fertilizer discharge pipe. After the left shell (103) and the right shell (104) are glued together by the groove, the upper end of the outer shell (Ⅰ) is connected to the fertilizer discharge port of the fertilizer dispenser, and the lower end is connected to the fertilizer discharge pipe.

3. A method for detecting fertilizer discharge using a granular fertilizer flow sensor according to claim 1 or 2, characterized in that, Includes the following steps: Step 1: After the granular fertilizer flow sensor is powered on, the linear laser emitter (109) emits an infrared light source with a projection shape of a horizontal line. The infrared light source is located at the focal point of the Fresnel collimating lens (106). The light path is adjusted to thin-surface parallel light by the Fresnel collimating lens (106) and radiates into the space between the left housing (103) and the right housing (104) of the sensor. Step 2: When fertilizer particles flow out from the fertilizer discharge port of the fertilizer dispenser, the fertilizer particles fall into the outer shell (Ⅰ) of the granular fertilizer flow sensor from the lower fertilizer discharge port of the fertilizer dispenser, and impact the turbine blade (110) at a certain speed, causing the turbine blade (110) to rotate. The clusters of fertilizer particles are dispersed under the drive of the turbine blade (110) and are evenly distributed in the outer shell (Ⅰ). Step 3: The dispersed fertilizer particles block part of the thin-surface parallel light adjusted by the Fresnel collimating lens (106) between the left shell (103) and the right shell (104). The remaining infrared light source is focused on the infrared phototransistor (112) by the Fresnel focusing lens (102). The precision resistor (113) is connected to the collector of the infrared phototransistor (112) to convert the change in collector current into the change in voltage across the precision resistor (113). Step 4: By collecting the potential difference between the collector of the infrared phototransistor (112) and the precision resistor (113) and the zero reference potential, the change in light intensity is converted into a voltage change signal. The voltage change signal is amplified by the pre-low-pass filter (114) and high-frequency noise signals are filtered out. Then, it is converted into a digital signal by the analog-to-digital converter integrated circuit (115). After digital filtering by the DSP digital signal processing module (116), the flow data is obtained. Finally, the flow data is transmitted to the display and control terminal through the CAN communication module (117).

4. A dual closed-loop variable fertilizer application control system based on CAN bus communication using the granular fertilizer flow sensor according to claim 1 or 2, characterized in that, Includes an integrated display and control terminal, a CAN parsing module, a GNSS positioning module, a CAN communication bus, a fertilizer box (118) equipped with a granular fertilizer flow sensor, and a multi-channel motor driver; The fertilizer box (118) is equipped with four electrically driven fertilizer discharge units, each of which consists of a DC motor (121) with an encoder, an outer grooved wheel fertilizer discharger (119), and a granular fertilizer flow sensor (120). The integrated display and control terminal determines the target fertilization amount and motor speed based on the input soil fertility information, and sends the speed information to the motor drive through the control system. The control process of the dual closed-loop variable fertilization control system includes two feedback loops, namely the feedback from the DC motor (121) with encoder and the granular fertilizer flow sensor (120); Among them, the rotation speed and flow rate information are fed back to the main control terminal through the CAN communication bus. The dual closed-loop variable fertilization control system combines the feedback information with the target fertilization amount and adjusts the rotation speed of the encoder-equipped DC motor (121) through the multi-channel motor driver to realize variable control of fertilization amount. The integrated display and control terminal dynamically displays the flow information fed back by the granular fertilizer flow sensor (120) in each fertilizer discharge unit through a bar chart. It monitors the blockage of the fertilizer discharge pipeline through the flow information in the bar chart and calculates the estimated operation time based on the fed-back flow information.

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