Grain cleaning loss detection device and detection method

Abstract

The present invention provides a grain cleaning loss detection device and method, comprising a sound-generating device, a sound sensor, a signal processor, a controller, and an alarm. The sound-generating device is a metal plate. The sound sensor comprises a first-order resonant cavity, a bent resonant cavity, a vibrating membrane, a cylindrical magnet, and a coil. The vibrating membrane deforms and vibrates upon contact with sound waves amplified by the first-order resonant cavity and the bent resonant cavity. Under the action of the vibrating membrane, the coil cuts magnetic flux lines relative to the cylindrical magnet, generating an induced current that is transmitted to the signal processor. The signal processor amplifies the grain sound signal. The controller de-noises, identifies, and counts the received grain sound signal, compares it with a preset value, and controls the alarm device to emit an alarm signal if the value exceeds the preset value. The present invention enables real-time monitoring of harvester cleaning loss in a strong noise environment, effectively improving the accuracy of grain cleaning loss monitoring.

Description

Technical Field

[0001] The present invention belongs to the technical field of intelligent agricultural machinery, and in particular relates to a grain cleaning loss detection device and a detection method. Background Art

[0002] With the increasing prevalence of agricultural mechanization in my country, combine harvesters have become the primary force in harvesting operations. Harvesting losses are inevitable, and operators often need to mitigate these losses by changing the harvesting speed, controlling the throttle, and adjusting the header. Harvesting losses include header loss, threshing loss, separation loss, and cleaning loss. Under normal operating conditions, header loss is less than 0.5%, cleaning loss accounts for 80%, and entrainment loss accounts for 10%. These four types of losses severely impact combine harvester performance. Cleaning loss is difficult to detect during operation but has the greatest impact. To better monitor the operating status of the combine harvester, it is essential to provide operators with real-time information on the extent of grain cleaning loss.

[0003] However, there are many types of combine harvesters, and the equipment varies greatly from generation to generation. Different combines exhibit varying degrees of grain cleaning loss. To reduce unnecessary losses and improve grain yield, developing a highly accurate and cost-effective cleaning loss sensor is imperative. Currently, most cleaning loss sensors rely on piezoelectric signals generated by grain impact and machine vision to detect cleaning loss. However, these two technologies each suffer from issues such as dust obscuring the camera during use, and the complex amplitudes of the piezoelectric material impacted by a mixture of materials, making it difficult to discern. Summary of the Invention

[0004] In response to the above technical problems, the present invention provides a grain cleaning loss detection device and method, which realizes the recognition and collection of grain sound signals under the strong noise background of the harvester in working condition, effectively improving the monitoring accuracy of grain cleaning loss.

[0005] The present invention utilizes sound sensing technology, signal processing technology and wavelet denoising principle to amplify, identify and collect grain sound signals under a strong noise background, thereby realizing real-time monitoring of harvester cleaning losses. When the cleaning loss rate exceeds a preset value, an alarm is issued to remind the operator to control the operating speed in real time, thereby effectively improving the monitoring accuracy of grain cleaning losses.

[0006] The present invention utilizes sound signals to monitor harvester cleaning loss, providing a different approach to cleaning loss detection.

[0007] The present invention solves the problem of large background noise and difficulty in distinguishing in grain cleaning loss detection based on sound signals.

[0008] The present invention can amplify sound signals of specific frequencies, achieve effective differentiation of sound signals between grains and stalks, and improve the accuracy of cleaning loss monitoring.

[0009] The present invention achieves the above technical objectives through the following technical means.

[0010] A grain cleaning loss detection device includes a sound generating device, a sound sensor, a signal processor, a controller and an alarm device;

[0011] The sound-generating device is a metal plate, which is used to be installed at the air outlet of the cleaning device;

[0012] The sound sensor is installed on the back of the metal plate to collect the sound signal of the grain hitting the metal plate; the sound sensor includes a first-order resonant cavity, a bent resonant cavity, a vibrating film, a cylindrical magnet and a coil; the first-order resonant cavity is a cylindrical cover-shaped structure, and the first-order resonant cavity is connected to one end of the bent resonant cavity; a bent cylindrical cavity is opened inside the bent resonant cavity, and a mounting hole is opened at the bottom of the bent cylindrical cavity, and the outer edge of the vibrating film is installed above the mounting hole at the bottom of the bent resonant cavity; the coil is connected to the vibrating film and spirally wound around the outer periphery of the cylindrical magnet, and the coil can move along the axial direction of the cylindrical magnet under the clamping of the vibrating film; the vibrating film deforms and vibrates after contacting the sound wave amplified by the first-order resonant cavity and the bent resonant cavity; under the action of the vibrating film, the coil cuts the magnetic flux lines relative to the cylindrical magnet, generates induced currents of different sizes, and transmits them to the signal processor;

[0013] The signal processor is used to amplify the grain sound signal and transmit it to the controller;

[0014] The controller is connected to the signal processor and the alarm device respectively. The controller performs denoising, identification and counting on the received grain sound signals and compares them with the preset value. If the value is higher than the preset value, the controller controls the alarm device to send out an alarm signal.

[0015] In the above solution, the signal processor includes an amplifying circuit and an AD conversion module;

[0016] The amplifier circuit is connected to the sound sensor and the controller respectively, and transmits the sound collected by the sound sensor to the controller after amplifying and suppressing;

[0017] The AD conversion module converts the analog signal collected by the sound sensor and processed by the amplification circuit into a digital signal.

[0018] In the above solution, the controller includes a denoising module, a counting module and an alarm module;

[0019] The denoising module is used to process the amplified sound signal through wavelet denoising to identify the grain sound signal;

[0020] The counting module is used to count the grain sound signals and compare them with a preset value. If the number is higher than the preset value, an instruction is sent to the alarm module.

[0021] The alarm module is used to control the alarm device to send out an alarm signal according to the instruction sent by the counting module.

[0022] In the above solution, a tube seat is provided at the mounting hole, and a shell is provided on the tube seat; the cylindrical magnet passes through one end of the shell and is connected to the fixed cover plate, and the fixed cover plate is installed at the other end of the shell.

[0023] In the above solution, the side length ratio of the metal plate is 1:1, and it is installed at the air outlet of the cleaning device by fixing the four sides. This fixing method can effectively ensure the stability of the sound signal generated by the impact.

[0024] In the above solution, the linear dimension of the first-order resonant cavity needs to be much smaller than the wavelength of the sound wave to be measured; the bending angle β of the bent resonant cavity is 100°, and the lengths L1 and L2 of the two sections of the cavity tube of the bent part are equal.

[0025] In the above solution, the material of the vibration film is graphene.

[0026] The above solution also includes a sponge filter; the sponge filter is installed at the front end of the first-order resonant cavity.

[0027] The above solution also includes a display screen, and the display screen and the controller are connected.

[0028] A detection method according to the grain cleaning loss detection device comprises the following steps:

[0029] The sound sensor collects sound signals of the grains hitting the metal plate;

[0030] When the sound wave enters the first-order resonant cavity of the sound sensor, the air in the first-order resonant cavity gradually concentrates toward the bottom of the curved resonant cavity, the air in the cavity is compressed, and the sound pressure gradually increases. When the sound wave reaches the bottom of the curved resonant cavity, the sound pressure reaches its maximum.

[0031] The vibration film vibrates under the action of the amplified sound waves, driving the coil fixed on the vibration film to cut the magnetic lines of force along the axial direction of the cylindrical magnet. The coil generates an induced current, which is further amplified by the signal processor. The amplified analog current signal enters the controller. The controller denoises and counts the received grain sound signals, and compares them with the preset value. If it is higher than the preset value, the alarm device is controlled to send an alarm signal.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention realizes the recognition and collection of grain sound signals under the strong noise background of the harvester working state, effectively improving the monitoring accuracy of grain cleaning loss.

[0034] 2. The present invention utilizes sound sensing technology, signal processing technology, and wavelet denoising to amplify, identify, and collect grain sound signals in a strong noise background, effectively improving the monitoring accuracy of grain cleaning losses, counting the grains dropped during the cleaning process, and realizing real-time monitoring of harvester cleaning losses. When the cleaning loss rate exceeds a preset value, an alarm is issued to remind the harvester to control the operating speed in real time.

[0035] 3. This invention uses sound signals to monitor harvester cleaning losses, providing a different method for cleaning loss detection.

[0036] 4. The present invention solves the problem of large background noise and difficulty in distinguishing in grain cleaning loss detection based on sound signals.

[0037] 5. The present invention can amplify sound signals of specific frequencies, effectively distinguish the sound signals of grains and stalks, and improve the accuracy of cleaning loss monitoring.

[0038] Note that the description of these effects does not hinder the existence of other effects, and effects other than the above can be clearly seen and extracted from the description of the specification, drawings, claims, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic structural diagram of a grain cleaning loss detection device according to one embodiment of the present invention;

[0040] Figure 2 It is a schematic diagram of a grain cleaning loss detection device according to one embodiment of the present invention;

[0041] Figure 3 1 is an equivalent schematic diagram of a second-order bent resonant cavity according to an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of the overall installation method of one embodiment of the present invention;

[0043] Figure 5 Schematic diagram of the vibration of metal plates with different fixing methods after being hit by grains according to one embodiment of the present invention, wherein Figure 5 (a) One side is fixed, Figure 5 (b) is fixed on the opposite side, Figure 5 (c) fixed on four sides;

[0044] Figure 61 is a schematic structural diagram of a sound-generating device according to an embodiment of the present invention;

[0045] Figure 7 : This is a sound-solid coupling sound pressure level distribution diagram of the resonant cavity with a bending angle of 90° according to an embodiment of the present invention;

[0046] Figure 8 : This is a distribution diagram of the acoustic-solid coupling sound pressure level when the resonant cavity bending angle is 100° according to an embodiment of the present invention;

[0047] Figure 9 This is a distribution diagram of the acoustic-solid coupling sound pressure level when the resonant cavity bending angle is 110° according to an embodiment of the present invention;

[0048] Figure 10 : This is a sound-solid coupling sound pressure level distribution diagram of the resonant cavity with a bending angle of 120° according to an embodiment of the present invention;

[0049] Figure 11 : This is a sound pressure level distribution diagram of the acoustic-solid coupling when the resonant cavity bending angle is 130° according to an embodiment of the present invention;

[0050] Figure 12 : This is a sound-solid coupling sound pressure level distribution diagram of the resonant cavity with a bending angle of 140° according to an embodiment of the present invention;

[0051] Figure 13 : This is a sound pressure level distribution diagram of the acoustic-solid coupling when the resonant cavity bending angle is 150° according to an embodiment of the present invention;

[0052] Figure 14 : This is a sound-solid coupling sound pressure level distribution diagram of the resonant cavity with a bending angle of 160° according to an embodiment of the present invention;

[0053] Figure 15 : This is a sound pressure level distribution diagram of the acoustic-solid coupling when the resonant cavity bending angle is 170° according to an embodiment of the present invention;

[0054] Figure 16 : This is a sound-solid coupling sound pressure level distribution diagram of the resonant cavity with a bending angle of 180° according to an embodiment of the present invention;

[0055] Figure 17 is a schematic diagram of an amplifier circuit according to an embodiment of the present invention;

[0056] Figure 18 is a time domain diagram of the signal before and after denoising according to an embodiment of the present invention, Figure 18 (a) is the signal time domain diagram before denoising. Figure 18 (b) is the time domain diagram of the signal after denoising.

[0057] Among them: 1-sponge filter, 2-first-order resonant cavity, 3-bent resonant cavity, 4-vibrating film, 5-tube seat, 6-housing, 7-fixed cover, 8-coil, 9-cylindrical magnet, 10-amplifier circuit, 11-controller, 12-display screen, 13-metal plate; 14-alarm speaker, 15-grain, 16-signal processing box, 17-sound sensor. DETAILED DESCRIPTION

[0058] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0059] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "front", "back", "left", "right", "up", "down", "axial", "radial", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0060] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0061] Figure 1 Figure 2 and Figure 3The figure shows a preferred embodiment of the grain cleaning loss detection device, which is a method for detecting grain cleaning loss based on the principles of resonant cavity amplification and wavelet denoising. This invention recognizes and collects grain sound signals even against the strong noise background of a harvester during operation, effectively improving the accuracy of grain cleaning loss monitoring.

[0062] The grain cleaning loss detection device includes a sound generating device, a sound sensor and a signal processor.

[0063] In one embodiment of the present invention, the sound-generating device is a metal plate 13 fixed to the tail of the harvester; preferably, the metal plate 13 is installed at the air outlet of the cleaning device.

[0064] The sound sensor is mounted on the back of the metal plate 13 to collect the sound signal of the grains hitting the metal plate 13. The present invention uses sound signals to monitor the harvester's cleaning loss, providing a different way for the cleaning loss detection method.

[0065] In one embodiment of the present invention, the sound sensor includes a first-order resonant cavity 2, a bent resonant cavity 3, a vibrating film 4, a cylindrical magnet 9 and a coil 8; the first-order resonant cavity 2 is a cylindrical cover-like structure, and the first-order resonant cavity 2 is connected to one end of the bent resonant cavity 3; a bent cylindrical cavity is opened inside the bent resonant cavity 3, and a mounting hole is opened at the bottom of the bent cylindrical cavity, and the outer edge of the vibrating film 4 is installed above the mounting hole at the bottom of the bent resonant cavity 3; the coil 8 is connected to the vibrating film 4 and is spirally wound around the outer periphery of the cylindrical magnet 9. The coil 8 can move along the axial direction of the cylindrical magnet 9 under the clamping of the vibrating film 4.

[0066] The vibrating film 4 deforms and vibrates after coming into contact with the sound waves amplified by the first-order resonant cavity 2 and the bent resonant cavity 3; the coil 8 moves relative to the cylindrical magnet 9 to cut the magnetic flux lines under the action of the vibrating film 4, generating induced currents of different sizes, and transmitting them to the signal processor.

[0067] The signal processor is used to amplify the grain sound signal and transmit it to the controller 11.

[0068] The controller 11 is connected to the signal processor and the alarm device, respectively. The controller 11 performs noise reduction, identification, and counting on the received grain sound signals, and compares the received grain sound signals with a preset value. If the received grain sound signals exceed the preset value, the controller 11 controls the alarm device to issue an alarm signal. The present invention solves the problem of high background noise and difficulty in distinguishing grain loss in grain cleaning loss detection based on sound signals.

[0069] In one embodiment of the present invention, the diameter of the coil 8 is slightly larger than the diameter of the cylindrical magnet 9 , and the coil 8 can move along the axial direction of the cylindrical magnet 9 while being clamped by the vibrating film 4 .

[0070] In one embodiment of the present invention, a tube seat 5 is provided at the mounting hole, and a shell 6 is provided on the tube seat 5; the cylindrical magnet 9 passes through one end of the shell 6 and is connected to the fixed cover plate 7, and the fixed cover plate 7 is installed at the other end of the shell 6.

[0071] In one embodiment of the present invention, the first-order resonant cavity 2 is connected to the boss at the left end of the bent resonant cavity 3 via a thread.

[0072] In one embodiment of the present invention, the bent resonant cavity 3 is a rectangular parallelepiped structure.

[0073] In one embodiment of the present invention, the signal processor includes an amplifying circuit 10 and an AD conversion module;

[0074] The amplifier circuit is connected to the sound sensor and the controller 11 respectively, and transmits the sound collected by the sound sensor to the controller 11 after amplification and suppression. The present invention can amplify sound signals of specific frequencies, effectively distinguish the sound signals of grains and stalks, and improve the accuracy of cleaning loss monitoring.

[0075] The AD conversion module converts the analog signal collected by the sound sensor and processed by the amplifying circuit 10 into a digital signal.

[0076] In one embodiment of the present invention, the controller 11 includes at least a denoising module, a counting module and an alarm module;

[0077] The denoising module is used to process the amplified sound signal through wavelet denoising to identify the grain sound signal;

[0078] The counting module is used to count the grain sound signals and compare them with a preset value. If the number is higher than the preset value, an instruction is sent to the alarm module.

[0079] The alarm module is used to control the alarm device to send out an alarm signal according to the instruction sent by the counting module. Figure 2 As shown, the vibrating film 4 is made of graphene, which is highly flexible and very thin, effectively reflecting the characteristics of sound waves. Upon contact with the sound waves amplified by the resonant cavity, the vibrating film 4 deforms and vibrates. Under the action of the vibrating film 4, the coil 8 cuts through the magnetic flux lines relative to the cylindrical magnet 9, generating induced currents of varying magnitudes. As the frequency of the collected sound waves increases, the vibration frequency of the vibrating film 4 increases, and accordingly, the speed at which the coil 8 cuts through the magnetic flux lines increases, resulting in a higher voltage. As the amplitude of the collected sound waves increases, the vibration amplitude of the vibrating film 4 increases, and the amplitude of the coil 8 cutting through the magnetic flux lines also increases, resulting in a higher induced current.

[0080] In one embodiment of the present invention, preferably, a sponge filter 1 is further included; the sponge filter 1 is installed at the front end of the first-order resonant cavity 2 to reduce the entry of materials and dust into the resonant cavity during the operation of the harvester.

[0081] Combined with attachment Figure 3 As shown, the first-order resonant cavity 2 and the bent resonant cavity 3 form a complete resonant cavity, which can continuously resonate and amplify the sound waves emitted by the impact of the grains; the linear dimension of the first-order resonant cavity 2 needs to be much smaller than the wavelength of the sound wave to be measured, that is,

[0082]

[0083] Where r represents the radius of the first-order resonant cavity; l represents the length of the first-order resonant cavity; V2 represents the cavity volume of the bent resonant cavity; and λ represents the wavelength of the sound signal to be detected.

[0084] The linear dimension of the first-order resonant cavity 2 is much smaller than the wavelength of the sound wave to be measured in order to ensure resonance of the sound wave to be measured. The effective mass of the air in the first-order resonant cavity 2 and the elasticity of the air in the bending resonant cavity 3 can form a vibration system.

[0085] In one embodiment of the present invention, the resonant frequency of the resonant cavity is determined by the size of the resonant cavity, and the specific expression is:

[0086]

[0087] Where f represents the resonant frequency;

[0088] c is the speed of sound; S1 is the cross-sectional area of ​​the first-order resonant cavity;

[0089] γ is the correction factor for the mass load caused by entrained air near the end of the first-order resonant cavity.

[0090] The size of the resonant cavity is designed according to the frequency of the grain signal to be detected. To ensure a significant resonant state and equal eigenfrequencies of the bent portions, the lengths L1 and L2 of the two sections of the bent portion of the bent resonant cavity 3 used in the present invention are equal.

[0091] When the incident sound wave contains a sound wave with the same resonant frequency as the resonant cavity, the sound wave in the cavity is a standing wave, and the sound pressure from the cavity entrance to any position in the cavity is:

[0092]

[0093] Where p z Indicates the sound pressure in the resonant cavity;

[0094] p0 is the sound pressure of the sound signal to be detected at the resonant cavity port;

[0095] L represents the length of the bending resonant cavity, i.e. L1+L2;

[0096] Z represents the distance between the position to be measured and the end of the first-order resonant cavity.

[0097] The sound pressure amplification factor at the resonant frequency when the bending angle β is 180° is:

[0098]

[0099] Where p1 represents the sound pressure of the signal to be measured at the entrance of the cavity;

[0100] p2 represents the sound pressure of the signal to be measured at the bottom of the cavity.

[0101] Combined with attachment Figure 5 As shown, different ways of securing the metal plate 13 affect the frequency and volume of the impact sound. Simulation models were created in Ls-Dyna for each of the following situations: a seed impacting a metal plate secured on one side, two sides, or four sides. The seed was set to strike a square aluminum plate (200 mm long and 1 mm thick) at a speed of 3 m / s perpendicular to the plate, with a calculation time of 0.08 s. Finally, displacement plots of the impact point perpendicular to the plate were calculated and plotted for each securing method. The vibration of the plate was observed through these displacement plots.

[0102] from Figure 5 It can be seen from a that the vibration frequency of the aluminum plate fixed on one side is relatively large after the impact, and the overall fluctuation of the metal plate is relatively large, and the amplitude distribution is extremely unstable; Figure 5 As can be seen from b, the vibration amplitude of the aluminum plates fixed on both sides is small at the beginning of the collision, and then a small jump occurs; Figure 5 c It can be seen that the frequency distribution and amplitude distribution of the four-side fixed type are the most stable; therefore, in one embodiment of the present invention, the four-side fixed type is selected as the fixing method of the metal plate 13.

[0103] Combined with attachment Figure 4 and attached Figure 6 As shown, in a specific embodiment of the present invention, the material of the metal plate 13 is aluminum alloy, the side length ratio of the metal plate 13 is 1:1, and it is fixed at the air outlet of the cleaning device at the tail of the harvester by a four-end fixing method. This fixing method can effectively ensure the stability of the sound signal generated by the impact.

[0104] In one embodiment of the present invention, square tubes are welded to the four sides of the metal plate 13 to secure the four sides, and the metal plate 13 is welded as a whole to the bottom of the signal processing box. The sound sensor is mounted on the suspended square tube on the back of the metal plate 13, and the controller 11 is installed in the signal processing box.

[0105] Combined with attachment Figure 7 To the attached Figure 16 As shown, in a specific embodiment of the present invention, the acoustic-solid coupling module in Comsol Multiphysics is used to establish a resonant cavity acoustic field model. In order to obtain the resonant frequency response and specific sound pressure amplification value when acting on the resonant cavity during the propagation of sound waves, the influence of sound reflection and radiation is fully considered during modeling. A second-order resonant cavity model is established in the software, and a rectangular domain is set to enclose the cavity. The outer boundary of the rectangular domain is set as the radiation boundary condition to minimize the reflection of the sound wave, indicating that the sound wave can propagate into a continuous free space. In order to obtain a plane incident sound wave, a background sound pressure field is set in front of the rectangular domain, the sound pressure of the incident plane wave is set, and a perfect matching layer is set in front of it to absorb the reflected sound wave and the sound radiation generated by the air movement near the first-order cavity. The perfect matching layer also has a good absorption effect on non-normal waves. At the same time, in order to more efficiently calculate the resonant cavity frequency response, the actual thickness and material parameters of the cavity are not set during the calculation process. Instead, the first-order cavity and second-order cavity walls of the cavity in the rectangular domain except for the entrance are directly set as internal hard sound field boundaries. When meshing the model, the maximum size of the mesh should not exceed 1 / 5 of the wavelength corresponding to the maximum frequency in the calculation frequency range. The perfect matching layer is stretched using rational coordinates and swept into eight layers, which has a better sound wave radiation absorption effect. A plane wave with a pressure of 1Pa (90dB) is set in front of the first-order resonant cavity, and the incident frequency is swept at 1Hz for simulation. The average value of the absolute sound pressure on the bottom end face of the cavity is obtained as the sound pressure amplification value. And by changing the resonant cavity bending angle β of the model, starting from 90° and ending at a bending angle β of 180°, a virtual simulation is performed every 10°. It can be obtained that the sound pressure amplification effect is best when the bending angle is 100°, and the sound pressure level at the highest point is 169dB, which is amplified by 79dB. Therefore, in a specific embodiment of the present invention, a bending angle β of 100° is selected.

[0106] Combined with attachment Figure 17 As shown, in a specific embodiment of the present invention, the amplifier circuit 10 is a differential input preamplifier that can amplify signals, isolate and buffer the front and rear stage units, suppress noise and improve the signal-to-noise ratio. Among them, the operational amplifier device uses the AD8007 high-precision integrated operational amplifier. This amplifier is a current feedback operational amplifier. Although it does not have a high input impedance, its high speed, ultra-low distortion and noise characteristics are more conducive to meeting the requirements of the charge amplifier circuit. Its bias current is 4uA, and the current noise spectral density is In addition, the amplifier circuit has the following characteristics and requirements: it improves the signal-to-noise ratio because the circuit has a greater amplification effect on the differential-mode signal, and its gain is much greater than the common-mode component (noise); the resistors R1, R2, and R3 that determine the amplification of the differential-mode signal have no effect on the common-mode rejection ratio, but the mismatch of R2 and R3 will cause differential-mode gain mismatch. Therefore, the accuracy of R1, R2, and R3 should be 1%, and metal film resistors or wirewound resistors should be selected to obtain optimal stability; the preamplifier stage has no amplification effect on the common-mode input signal (equivalent to noise or temperature drift), that is, it has no amplification effect on temperature drift signals or noise, so its input drift and noise are relatively small. The output voltage of the amplifier circuit Its voltage gain is Where V0 represents the sensor input voltage; R1, R2, R3, R4, R5, and R6 represent the size of each resistor.

[0107] Combined with attachment Figure 18 As shown, in a specific embodiment of the present invention, the wavelet type selected by the denoising module is symlet wavelet, which can decompose and reconstruct the signal with a scale factor of 8, further reducing the interference of noise; Figure 18 (a) is the signal time domain diagram before denoising. Figure 18 (b) is the time domain diagram of the signal after denoising. The denoising module sets a threshold for the amplitude of the reconstructed signal. If a signal exceeds the threshold, it is the grain sound signal.

[0108] Combined with attachment Figure 3 As shown, in one embodiment of the present invention, the display screen 12 displays the amplified and noise-reduced sound signal in real time to facilitate the machine operator to observe the cleaning loss situation in real time.

[0109] The alarm module sends out an alarm signal when the cleaning loss rate is higher than a preset value, which can promptly remind the machine operator to control the operation speed and reduce losses.

[0110] The detection method of the grain cleaning loss detection device comprises the following steps:

[0111] The sound sensor collects the sound signal of the grains hitting the metal plate 13;

[0112] The sound wave enters the first-order resonant cavity 2 of the sound sensor. The air in the first-order resonant cavity 2 gradually concentrates toward the bottom of the bent resonant cavity 3. The air in the cavity is compressed, and the sound pressure gradually increases. When the sound wave reaches the bottom of the bent resonant cavity 3, the sound pressure reaches its maximum.

[0113] The vibration film 4 vibrates under the action of the amplified sound waves, driving the coil 8 fixed on the vibration film 4 to cut the magnetic lines of force along the axial direction of the cylindrical magnet 9. The coil 8 generates an induced current, which is further amplified by the signal processor. The amplified analog current signal enters the controller 11. The controller 11 denoises, identifies and counts the received grain sound signals, and compares them with the preset value. If it is higher than the preset value, the alarm device is controlled to send an alarm signal.

[0114] In a specific embodiment of the present invention, the detection method of the grain cleaning loss detection device works as follows:

[0115] When a grain strikes the metal plate 13, it generates a sound signal of a specific frequency. This sound signal, disturbed by the operating noise of the harvester, enters the sound sensor and the first-order resonant cavity 2. At this point, the air within the first-order resonant cavity 2 gradually converges toward the bottom of the curved resonant cavity 3, compressing the air and gradually increasing the sound pressure. When the sound wave reaches the bottom of the curved resonant cavity 3, the sound pressure reaches its maximum. The amplified sound wave causes the vibrating membrane 4 to vibrate and deform accordingly, driving the coil 8 affixed to the vibrating membrane 4 to move along the axial direction of the cylindrical magnet 9, cutting through the magnetic flux lines. Coil 8 generates an induced current of corresponding magnitude. This induced current is further amplified by the differential amplifier circuit 10, improving its resolution. The amplified analog current signal enters the controller 11, where it is converted to a digital signal after passing through the A / D conversion module. It then enters the wavelet denoising module, where, after decomposition and reconstruction using the symlet wavelet, the characteristics of the grain sound signal, previously obscured by the noise, are restored. When the signal amplitude exceeds a set threshold, it is considered a grain sound signal. The controller 11 counts this characteristic to monitor grain cleaning losses. When the cleaning loss rate reaches a preset value, the alarm speaker 14 will sound an alarm to remind the operator.

[0116] This invention utilizes sound sensing technology, signal processing techniques, and wavelet denoising principles to effectively capture and identify the acoustic signal characteristics of grains even in strong noise environments, effectively improving the accuracy of monitoring grain cleaning losses. It also counts dropped grains during the cleaning process, enabling real-time monitoring of harvester cleaning losses. When the cleaning loss rate exceeds a preset value, an alarm is issued, prompting the harvester operator to control operating speed in real time.

[0117] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0118] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A grain cleaning loss detection device, characterized in that: It includes a sound generating device, a sound sensor, a signal processor, a controller (11) and an alarm device; The sound-generating device is a metal plate (13), and the metal plate (13) is used to be installed at the air outlet of the cleaning device; The sound sensor is mounted on the back of the metal plate (13) and is used to collect sound signals of the seeds hitting the metal plate (13); the sound sensor comprises a first-order resonant cavity (2), a bent resonant cavity (3), a vibration film (4), a cylindrical magnet (9) and a coil (8); the first-order resonant cavity (2) is a cylindrical cover-shaped structure, and the first-order resonant cavity (2) is connected to one end of the bent resonant cavity (3); a bent cylindrical cavity is opened inside the bent resonant cavity (3), and a mounting hole is opened at the bottom of the bent cylindrical cavity. The outer edge of the vibration film (4) is mounted on the bent resonant cavity ( 3) above the bottom mounting hole; the coil (8) is connected to the vibration film (4) and is spirally wound around the outer periphery of the cylindrical magnet (9), and the coil (8) can move along the axial direction of the cylindrical magnet (9) under the clamping of the vibration film (4); the vibration film (4) deforms and vibrates after contacting the sound wave amplified by the first-order resonant cavity (2) and the bending resonant cavity (3); the coil (8) cuts the magnetic flux lines relative to the cylindrical magnet (9) under the action of the vibration film (4), generates induced currents of different sizes, and transmits them to the signal processor; The signal processor is used to amplify the grain sound signal and transmit it to the controller (11); The controller (11) is connected to the signal processor and the alarm device respectively. The controller (11) performs denoising, identification and counting on the received grain sound signal and compares it with a preset value. If the value is higher than the preset value, the alarm device is controlled to send an alarm signal. The controller (11) comprises at least a denoising module, a counting module and an alarm module; The denoising module is used to process the amplified sound signal through wavelet denoising to identify the grain sound signal; The counting module is used to count the grain sound signals and compare them with a preset value. If the number is higher than the preset value, an instruction is sent to the alarm module. The alarm module is used to control the alarm device to send out an alarm signal according to the instruction sent by the counting module; The metal plate (13) is installed at the air outlet of the cleaning device by fixing the four sides; The linear dimension of the first-order resonant cavity (2) needs to be much smaller than the wavelength of the sound wave to be measured; the bending angle β of the bent resonant cavity (3) is 100°, and the lengths L1 and L2 of the two sections of the cavity tube of the bent part are equal.

2. The grain cleaning loss detection device according to claim 1, characterized in that: The signal processor includes an amplifying circuit (10) and an AD conversion module; The amplifying circuit is connected to the sound sensor and the controller (11) respectively, and transmits the sound collected by the sound sensor to the controller (11) after amplifying and suppressing the sound; The AD conversion module converts the analog signal collected by the sound sensor and processed by the amplification circuit (10) into a digital signal.

3. The grain cleaning loss detection device according to claim 1, characterized in that: A tube seat (5) is provided at the mounting hole, and a housing (6) is provided on the tube seat (5); the cylindrical magnet (9) passes through one end of the housing (6) and is connected to the fixed cover plate (7), and the fixed cover plate (7) is installed at the other end of the housing (6).

4. The grain cleaning loss detection device according to claim 1, characterized in that: The side length ratio of the metal plate (13) is 1:

1.

5. The grain cleaning loss detection device according to claim 1, characterized in that: The material of the vibration film (4) is graphene.

6. The grain cleaning loss detection device according to claim 1, characterized in that: It also includes a sponge filter (1); the sponge filter (1) is installed at the front end of the first-order resonant cavity (2).

7. The grain cleaning loss detection device according to claim 1, characterized in that: It also includes a display screen (12), which is connected to the controller (11).

8. A detection method for a grain cleaning loss detection device according to any one of claims 1 to 7, characterized in that: The following steps are involved: The sound sensor collects sound signals of the grains hitting the metal plate (13); the sound wave enters the first-order resonant cavity (2) of the sound sensor, and the air in the first-order resonant cavity (2) gradually concentrates toward the bottom of the bent resonant cavity (3), the air in the cavity is compressed, and the sound pressure gradually increases. When the sound wave reaches the bottom of the bent resonant cavity (3), the sound pressure reaches a maximum. The vibrating film (4) vibrates under the action of the amplified sound waves, driving the coil (8) fixed on the vibrating film (4) to move along the axial direction of the cylindrical magnet (9) to cut the magnetic flux lines. The coil (8) generates an induced current, which is further amplified by the signal processor. The amplified analog current signal enters the controller (11). The controller (11) performs denoising, identification, and counting on the received grain sound signal, and compares it with a preset value. If the value is higher than the preset value, the alarm device is controlled to emit an alarm signal.

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