Nondestructive testing device and method for watermelon internal quality distribution uniformity

Abstract

The application provides a watermelon internal quality distribution uniformity nondestructive detection device and method, which is applied to the technical field of watermelon quality nondestructive detection, and comprises a three-dimensional multispectral collection module, a signal collection control circuit, a microprocessor and a display module.The three-dimensional multispectral collection module is used for collecting photoelectric signals of a measured watermelon through a preset light source wavelength combination to obtain a transmission light signal.The signal collection control circuit is used for driving the three-dimensional multispectral collection module in response to a control signal.The microprocessor is used for sending the control signal to the signal collection control circuit, receiving the transmission light signal transmitted by the three-dimensional multispectral collection module, and performing three-dimensional distribution inversion of watermelon sugar content and watermelon hardness based on the transmission light signal to obtain a watermelon detection signal.The display module is used for receiving the watermelon detection signal transmitted by the microprocessor, generating a three-dimensional sugar content and hardness distribution diagram corresponding to the measured watermelon based on the watermelon detection signal, and displaying the three-dimensional sugar content and hardness distribution diagram.The application can improve the accuracy and reliability of nondestructive watermelon quality evaluation.

Description

Technical Field

[0001] This invention relates to the field of non-destructive testing technology for watermelon quality, and in particular to a non-destructive testing device and method for the uniformity of internal quality distribution in watermelons. Background Technology

[0002] During watermelon growth, sugar accumulation and distribution, as well as flesh firmness, are influenced by a variety of factors, including variety, planting conditions (such as soil type, water supply, and sunlight), and maturity, making quality distribution measurement extremely complex. Different watermelon varieties exhibit significant differences in sugar content and firmness distribution patterns, and changes in the planting environment can also lead to uneven quality distribution. Furthermore, harvesting at unsuitable maturity further exacerbates quality inconsistencies.

[0003] Traditional testing methods require destructive sampling and manual inspection, with watermelon sugar content testing primarily relying on measurements at a single location or assessments of overall sugar content. For example, common methods include using a refractometer to measure the sugar content of watermelon juice or measuring the firmness of the flesh through a compression test. However, these methods have significant limitations. Measurements at a single location are insufficient to reflect the overall internal sugar content distribution of the watermelon, while assessments of overall sugar content and firmness fail to reveal the specific internal distribution.

[0004] Therefore, it is evident that the watermelon internal quality testing methods in the relevant technologies have a technical problem: they cannot comprehensively and accurately evaluate the quality of watermelons without causing damage. Summary of the Invention

[0005] This invention provides a non-destructive testing device and method for the uniformity of internal quality distribution in watermelons, which solves the problem that existing methods for testing the internal quality of watermelons cannot comprehensively and accurately evaluate the quality of watermelons without damage, thereby improving the accuracy and reliability of watermelon quality assessment.

[0006] This invention provides a non-destructive testing device for the uniformity of internal quality distribution in watermelons, comprising: a three-dimensional multispectral acquisition module for acquiring photoelectric signals from the watermelon under test using a preset combination of light source wavelengths to obtain transmitted light signals; a signal acquisition control circuit, communicatively connected to the three-dimensional multispectral acquisition module, for driving the three-dimensional multispectral acquisition module in response to a control signal; a microprocessor, communicatively connected to both the signal acquisition control circuit and the three-dimensional multispectral acquisition module, for sending the control signal to the signal acquisition control circuit and receiving the transmitted light signals transmitted by the three-dimensional multispectral acquisition module, performing a three-dimensional inversion of the watermelon's sugar content and hardness distribution based on the transmitted light signals to obtain a watermelon detection signal; a display module, communicatively connected to the microprocessor, for receiving the watermelon detection signal transmitted by the microprocessor, generating a three-dimensional sugar content and hardness distribution map corresponding to the watermelon under test based on the watermelon detection signal, and displaying the three-dimensional sugar content and hardness distribution map; and a power supply module, electrically connected to the signal acquisition control circuit, the microprocessor, and the display module, powered by a 220V AC to 24V DC switching power supply.

[0007] According to the present invention, a non-destructive testing device for the uniformity of internal quality distribution of watermelon is provided. The three-dimensional multispectral acquisition module includes: a photoelectric acquisition module, an electric opening and closing mechanism, and a fruit holder. The photoelectric acquisition module is installed on the electric opening and closing mechanism, which is used to open or close the photoelectric acquisition module. The photoelectric acquisition module is used to collect the projection spectrum and reflection spectrum of the watermelon under test in a closed testing space. The fruit holder is installed in the middle of the electric opening and closing mechanism, forming a cross base with the electric opening and closing mechanism.

[0008] According to the present invention, a non-destructive testing device for the uniformity of internal quality distribution of watermelon is provided. The photoelectric acquisition module includes: a multi-wavelength ring light source, which is composed of multiple multi-wavelength light-emitting diode (LED) lamp boards arranged in a ring. Each multi-wavelength LED lamp board integrates multiple wavelength LEDs, and each wavelength LED is equipped with multiple LED beads. The multiple LED beads are arranged in a preset row and column pattern, and the multiple LED beads of each wavelength are independently controlled to turn on and off; a photodetector assembly, which includes multiple photodetectors distributed along the latitude direction and multiple photodetectors distributed along the longitude direction, forming a transmitted light signal acquisition array with a preset number of rows and columns. The ends of the photodetectors are equipped with retractable black rubber light-shielding sleeves to fit the surface of the watermelon being tested; a contoured micro-dark chamber, which is symmetrically divided into two half-shells. The side walls of the contoured micro-dark chamber are provided with a light source mounting area and upper and lower photodetector mounting areas. The light source mounting area is used to install the multi-wavelength ring light source, and the upper and lower photodetector mounting areas are used to install the photodetector assembly; light-shielding partitions are provided on both sides of the light source mounting area to limit the illumination angle to 0 degrees, and the upper and lower photodetector mounting areas are respectively arranged with photodetector slots of a preset number of rows and columns.

[0009] According to the present invention, a non-destructive testing device for the uniformity of internal quality distribution of watermelon is provided, wherein the photodetector is a photomultiplier tube, and the retractable black rubber light-shielding sleeve is an accordion-shaped retractable structure used to adapt to changes in the surface distance between the photomultiplier tube and the watermelon being tested.

[0010] According to the present invention, a non-destructive testing device for the uniformity of internal quality distribution of watermelon is provided. The contoured micro darkroom is closed by the two half-shells to form a closed testing space. The closed testing space is a complete hollow column used to shield environmental stray light interference.

[0011] According to the present invention, a non-destructive testing device for the uniformity of internal quality distribution of watermelon is provided. The electric opening and closing mechanism includes: a stepper motor and a linear module of a lead screw slide. The linear module of the lead screw slide includes a lead screw with a positive and negative thread structure. The lead screw is divided by its central axis, with the left half machined with a positive thread and the right half machined with a negative thread. A first slider and a second slider are respectively fitted on the positive thread and the negative thread. The output shaft of the stepper motor is coaxially connected to the lead screw. When the lead screw rotates clockwise, it drives the first slider and the second slider to move towards each other to achieve a closing action. When the lead screw rotates counterclockwise, it drives the two sliders to move away from each other to achieve an opening action.

[0012] According to the present invention, a non-destructive testing device for the uniformity of internal quality distribution of watermelon is provided. The wavelength combination of the light source includes a sensitive band of 1000-1400nm and a reference band of 700-750nm for sugar content detection, and a high absorption band of 850-1000nm for moisture content detection.

[0013] This invention also provides a non-destructive testing method for the uniformity of internal quality distribution in watermelons, comprising the following steps: acquiring photoelectric signals from the watermelon under test using a preset combination of light source wavelengths to obtain transmitted light signals; performing a three-dimensional inversion of the sugar content and hardness distribution of the watermelon based on the transmitted light signals to obtain watermelon detection signals; generating a three-dimensional sugar content and hardness distribution map corresponding to the watermelon under test based on the watermelon detection signals, and displaying the three-dimensional sugar content and hardness distribution map.

[0014] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the non-destructive testing method for the uniformity of internal quality distribution of watermelon as described above.

[0015] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the non-destructive testing method for the uniformity of internal quality distribution of watermelon as described above.

[0016] The present invention also provides a computer program product, including a computer program, which, when executed by a processor, implements the non-destructive testing method for the uniformity of internal quality distribution of watermelon as described above.

[0017] The present invention provides a non-destructive testing device and method for the uniformity of watermelon internal quality distribution. This device efficiently acquires transmitted light signals from the watermelon using a three-dimensional multispectral acquisition module combined with a preset light source wavelength combination, capturing the differences in light absorption and scattering characteristics of different tissues within the watermelon. A signal acquisition and control circuit ensures the synchronization and stability of photoelectric signal acquisition. A microprocessor performs three-dimensional distribution inversion of sugar content and firmness based on the transmitted signal, improving detection accuracy and efficiency. A display module intuitively presents a three-dimensional sugar content and firmness distribution map, facilitating rapid judgment of quality uniformity. The power supply module adopts an AC-to-DC conversion scheme, ensuring safe and reliable operation of the equipment. Overall, the device achieves non-destructive, rapid, and visual detection of the watermelon's internal quality. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced one by one below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a block diagram of the overall structure of the non-destructive testing device for the uniformity of internal quality distribution of watermelon provided by the present invention.

[0020] Figure 2 This is a schematic diagram of the structure of the multi-wavelength controllable LED light board provided by the present invention.

[0021] Figure 3 This is a schematic diagram of the structure of the multi-wavelength ring light source provided by the present invention.

[0022] Figure 4 This is a structural diagram of the contour-mimicking micro anechoic chamber provided by the present invention.

[0023] Figure 5 This is a three-dimensional structural diagram of the photoelectric acquisition module provided by the present invention.

[0024] Figure 6 This is a schematic diagram of the structure of the photodetector and the light-shielding sleeve provided by the present invention.

[0025] Figure 7 This is a structural diagram of the electric opening and closing mechanism provided by the present invention.

[0026] Figure 8 This is a schematic diagram of the fruit holder provided by the present invention.

[0027] Figure 9 This is the overall structure of the diffused light three-dimensional acquisition module provided by the present invention.

[0028] Figure 10 This is a schematic diagram of the basic method for detecting the sugar content and firmness distribution inside a watermelon provided by the present invention.

[0029] Figure 11 This is a schematic diagram illustrating the application scenario of the watermelon internal quality distribution detector provided by this invention.

[0030] Figure 12 This is a schematic diagram of the closed state of the three-dimensional multispectral acquisition module provided by the present invention.

[0031] Figure 13 This is a schematic diagram showing the powered-on state of the three-dimensional multispectral acquisition module provided by the present invention.

[0032] Figure 14 This is a schematic diagram of the physical structure of the electronic device provided by the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] Watermelon (Citrullus lanatus), a globally popular fruit, is beloved by consumers for its sweetness, juiciness, and rich nutrition. However, the internal quality of watermelons exhibits significant unevenness in sugar content and firmness. In terms of eating experience, the core is typically sweet and firm, while the flesh near the rind is lower in sugar, firmer, and may even be acidic, severely impacting consumers' overall perception of the watermelon's quality. During watermelon growth, sugar accumulation and distribution, as well as flesh firmness, are influenced by a multitude of factors, including variety, growing conditions (such as soil type, water supply, and sunlight), and maturity, making quality distribution measurement extremely complex. Different watermelon varieties show significant differences in sugar content and firmness distribution patterns, and variations in the growing environment can also lead to uneven quality distribution. Harvesting at unsuitable maturity further exacerbates this inconsistency.

[0035] Traditional testing methods require destructive sampling and manual inspection, with watermelon sugar content testing primarily relying on measurements at a single location or assessments of overall sugar content. For example, common methods include using a refractometer to measure the sugar content of watermelon juice (Brix value) or measuring the firmness of the flesh through a compression test. However, these methods have significant limitations. Measurements at a single location are insufficient to reflect the overall internal sugar content distribution of the watermelon, while assessments of overall sugar content and firmness fail to reveal the specific internal distribution, resulting in an inability to comprehensively and accurately evaluate the watermelon's quality.

[0036] Current fruit sugar content measuring instruments on the market, such as near-infrared spectrometers, can measure the sugar content of the whole fruit. Desktop watermelon spectrometers use a cold light source with a soft rubber light-shielding structure and can be used for fruit sugar content detection, but they are all single-point reflectance spectrometers, only suitable for measuring the sugar content of small, thin-skinned fruits at a single point. Spectrometers use fiber optic beam splitting for multi-point acquisition, but the spectra from multiple points are ultimately converged into the same spectrometer, only detecting the average sugar content of the area covered by the probe. The high water content and porous structure of watermelons make traditional electrochemical and optical detection methods susceptible to interference, making it difficult to achieve high-precision quality measurement. Furthermore, the complex internal structure of watermelons, containing a large amount of water and various cellular tissues, makes it difficult for existing imaging and sensing technologies to accurately distinguish changes in sugar content and firmness in different areas.

[0037] To address the uneven distribution of internal quality (including sugar content and firmness) in watermelons and the multiple challenges encountered in the detection process, developing a non-destructive testing method and device that can efficiently and accurately detect the internal quality distribution of watermelons has significant practical implications and broad application prospects.

[0038] To address the aforementioned issues, this invention proposes a watermelon internal hardness detection system based on near-infrared spectroscopy (NIR) and diffuse optical tomography (DOT). Near-infrared spectroscopy offers advantages such as speed, non-destructiveness, and the ability to penetrate thick rinds, making it suitable for preliminary sugar content and hardness detection. However, when using NIR alone in watermelons with high moisture content and complex tissue structures, the signal is easily absorbed and scattered, resulting in low detection accuracy. DOT, through multi-angle, multi-wavelength light signal acquisition and reconstruction, can generate a three-dimensional optical image of the watermelon's interior, providing more detailed and accurate internal structural information. Combining NIR and DOT effectively overcomes the limitations of single technologies, achieving high-precision, comprehensive detection of the sugar content and hardness distribution within the watermelon. Specifically, NIR technology is used to quickly acquire spectral information from the watermelon's interior, providing a preliminary assessment of the sugar content and hardness distribution; DOT technology further reconstructs the watermelon's interior through complex optical models, generating a detailed quality distribution image. This combination not only improves the accuracy of testing, but also enables the testing of the firmness of large batches of watermelons in a shorter time, meeting the needs of modern agricultural production for efficient and accurate testing.

[0039] Figure 1 This is a block diagram of the overall structure of the non-destructive testing device for the internal quality distribution uniformity of watermelons provided by the present invention, as shown below. Figure 1 As shown, the device includes:

[0040] 1. A three-dimensional multispectral acquisition module is used to acquire photoelectric signals from the watermelon under test through a preset combination of light source wavelengths to obtain transmitted light signals;

[0041] 2. Signal acquisition and control circuit, which is communicatively connected to 1. Three-dimensional multispectral acquisition module, is used to drive 1. Three-dimensional multispectral acquisition module in response to control signals;

[0042] Three microprocessors are connected to two signal acquisition and control circuits and one three-dimensional multispectral acquisition module, respectively. They are used to send control signals to the two signal acquisition and control circuits and receive the transmitted light signals transmitted by the one three-dimensional multispectral acquisition module. Based on the transmitted light signals, the three-dimensional distribution of watermelon sugar content and watermelon hardness is inverted to obtain the watermelon detection signal.

[0043] 4. Display module, which is connected to 3 microprocessors, is used to receive the watermelon detection signal transmitted by 3 microprocessors, generate a three-dimensional sugar content and hardness distribution map of the tested watermelon based on the watermelon detection signal, and display the three-dimensional sugar content and hardness distribution map.

[0044] The 5 power supply modules are electrically connected to the 2 signal acquisition and control circuits, the 3 microprocessor, and the 4 display module, respectively, and are powered by an AC 220V to DC 24V switching power supply.

[0045] The realization of diffuse optical tomography of watermelon requires measuring the optical flow distribution at other points on the surface under multi-point excitation. Figure 1 This is a block diagram of the overall structure of the non-destructive testing device for the internal quality distribution uniformity of watermelons provided by the present invention. It consists of 5 parts: 1. Three-dimensional multispectral acquisition module, 2. Acquisition control circuit, 3. Microprocessor, 4. Display module, and 5. Power supply module.

[0046] The instrument consists of five modules: 1) a 3D multispectral acquisition module responsible for acquiring photoelectric signals from the watermelon; 2) a signal acquisition control circuit that receives signals from the microprocessor (3) to drive the 3D multispectral acquisition module to perform acquisition; and 5) a power supply module that uses an AC 220V to DC 24V switching power supply, which can also be connected to an external robot power supply when the instrument is used as an end effector on a robot.

[0047] Through the embodiments of this invention, the transmitted light signal of watermelon is efficiently acquired by a three-dimensional multispectral acquisition module combined with a preset light source wavelength combination, which can capture the differences in the absorption and scattering characteristics of light by different tissues inside the watermelon; the signal acquisition control circuit ensures the synchronization and stability of photoelectric signal acquisition; the microprocessor realizes the three-dimensional distribution inversion of sugar content and hardness based on the transmitted signal, improving the detection accuracy and efficiency; the display module intuitively presents the three-dimensional sugar content and hardness distribution map, which facilitates the rapid judgment of quality uniformity; the power supply module adopts an AC to DC conversion scheme to ensure the safe and reliable operation of the equipment, and the whole system realizes non-destructive, rapid and visual detection of the internal quality of watermelon.

[0048] According to the present invention, a non-destructive testing device for the uniformity of internal quality distribution of watermelon, comprising a three-dimensional multispectral acquisition module, including: a photoelectric acquisition module, an electric opening and closing mechanism, and a fruit holder;

[0049] The photoelectric acquisition module is installed on the electric opening and closing mechanism, which is used to open or close the photoelectric acquisition module. The photoelectric acquisition module is used to collect the projection spectrum and reflection spectrum of the watermelon under test in a closed detection space.

[0050] The fruit holder is installed in the middle of the electric opening and closing mechanism, forming a cross base with the electric opening and closing mechanism.

[0051] The core component of the watermelon internal sugar content and hardness distribution detector (i.e., the non-destructive testing device for the uniformity of watermelon internal quality distribution) is a three-dimensional multispectral acquisition module, which consists of three parts: a photoelectric acquisition module, an electric opening and closing mechanism, and a fruit holder.

[0052] Through the embodiments of the present invention, the electric opening and closing mechanism drives the photoelectric acquisition module to dynamically close to form a closed detection space, effectively isolating ambient light interference; its adjustable opening and closing angle can adapt to watermelons of different sizes; the photoelectric acquisition module uses a multi-directional, multi-angle light source array and a high-sensitivity photoelectric sensor to synchronously collect the optical scattering characteristics of the watermelon surface and interior within the closed space, combined with the cross-shaped base positioning structure of the fruit holder, so that the watermelon under test remains stable and centered during the detection process, avoiding light signal deviation caused by displacement or tilt, and ensuring the consistency and reliability of data acquisition.

[0053] According to the present invention, a non-destructive testing device for the uniformity of internal quality distribution of watermelon, comprising a photoelectric acquisition module, includes:

[0054] The multi-wavelength ring light source is composed of multiple multi-wavelength LED lamp boards arranged in a ring. Each multi-wavelength LED lamp board integrates LEDs of multiple wavelengths. Each wavelength LED is equipped with multiple LED beads. The multiple LED beads are arranged in a preset row and column format. The multiple LED beads of each wavelength are independently controlled to turn on and off.

[0055] The photodetector assembly includes multiple photodetectors distributed along the latitude direction and multiple photodetectors distributed along the longitude direction, forming a transmitted light signal acquisition array with a preset number of rows and columns. The ends of the photodetectors are equipped with retractable black rubber light-shielding sleeves to fit the surface of the watermelon being tested.

[0056] The contoured miniature anechoic chamber is symmetrically divided into two half-shells. The side walls of the contoured miniature anechoic chamber are provided with a light source installation area and upper and lower photodetector installation areas. The light source installation area is used to install a multi-wavelength ring light source, and the upper and lower photodetector installation areas are used to install photodetector assemblies. Light-shielding partitions are set on both sides of the light source installation area to limit the illumination angle to 0 degrees. The upper and lower photodetector installation areas are respectively arranged with photodetector slots of a preset number of rows and columns.

[0057] In related technologies, when using diffusion spectroscopy to detect the internal quality of watermelons, high-resolution three-dimensional optical imaging is crucial for accurately reflecting the distribution of sugar content and firmness within the watermelon, serving as a key basis for quality assessment. However, the complex internal structure of watermelons, with its large amount of water and various cellular tissues, makes the light propagation path variable and difficult to resolve. The different densities, compositions, and arrangements of different tissues increase the complexity of light propagation, making it difficult for the detection system to distinguish subtle structural and characteristic differences, thus requiring extremely high system resolution and accuracy.

[0058] In an embodiment of the present invention, reference is made to Figure 2 , Figure 2This is a schematic diagram of the structure of the multi-wavelength controllable LED light board provided by the present invention, which includes: multiple LED beads corresponding to wavelength 1, multiple LED beads corresponding to wavelength 2, multiple LED beads corresponding to wavelength 3, multiple LED beads corresponding to wavelength 4, and multiple LED beads corresponding to wavelength 5.

[0059] Figure 2 This is a multi-wavelength light-emitting diode (LED) ring light source. The basic unit of the ring light source is a multi-wavelength lamp panel. Each lamp panel integrates 5 wavelengths of LEDs, with 3 LEDs per wavelength, arranged in a 5×3 pattern. The LEDs of each wavelength can be independently controlled to turn on and off. The wavelengths are selected using a traditional watermelon sugar content spectral detection method. Eighteen lamp panels are installed on a contoured miniature darkroom to form a ring light source.

[0060] refer to Figure 3 , Figure 3 This is a schematic diagram of the structure of the multi-wavelength ring light source provided by the present invention.

[0061] like Figure 3 As shown. When the light source is working, the same lamp panel is turned on and off sequentially according to wavelength. After one lamp panel is turned on and off, the operation of the previous lamp panel is repeated for the next lamp panel, until all lamp panels have completed one cycle of turning on and off. This achieves multi-wavelength, multi-position light source illumination.

[0062] It should be noted that traditional watermelon-style tabletop and detection equipment are both open-type, which cannot control stray light entering the photoelectric sensor, resulting in measurement errors and signal noise.

[0063] According to the present invention, a non-destructive testing device for the uniformity of internal quality distribution of watermelon is provided. The contoured micro dark chamber is closed by two half-shells to form a closed testing space. The closed testing space is a complete hollow column used to shield environmental stray light interference.

[0064] In an embodiment of the present invention, reference is made to Figure 4 , Figure 4 This is a structural diagram of the contour-mimicking micro anechoic chamber provided by the present invention.

[0065] Figure 4 This is a contour-following miniature anechoic chamber, serving two purposes: first, as a mounting base for a multi-wavelength ring light source and photodetectors; and second, to shield against ambient light, preventing stray light from entering the photodetectors and affecting the detection results. The contour-following miniature anechoic chamber is designed as an octagonal cylindrical shell, symmetrically divided into two half-shells. During operation, these half-shells close together to form a complete hollow cylinder, enclosing the watermelon within. The side walls of the half-shells are designed with upper and lower photodetector mounting areas and a light source mounting area. Light-shielding partitions on both sides of the light source mounting area limit the light source illumination angle to 0 degrees. The upper and lower mounting areas each have a 4×9 photodetector mounting space array for installing the photodetectors.

[0066] Through the embodiments of the present invention, a miniature darkroom is formed by the contour-mimicking light-blocking darkroom design. When working, the watermelon is completely enclosed inside, which can avoid interference from ambient light.

[0067] refer to Figure 5 , Figure 5 This is a three-dimensional structural diagram of the photoelectric acquisition module provided by the present invention, which includes: a light shield, a rubber tube for limiting the light acquisition field of view, a multi-wavelength LED combination light source, and a light source illumination angle limiting plate.

[0068] like Figure 5 As shown, a multi-wavelength ring light source and photodetectors are installed in the light source mounting area and the upper and lower photodetector mounting areas of the contour-mimicking micro anechoic chamber, respectively, forming two semi-open (three-dimensional) photoelectric signal acquisition modules. Eighteen photodetectors are distributed along the latitude direction on each layer, and eight photodetectors are distributed along the longitude direction, allowing for the detection of transmitted light signals at a total of 18×8 points.

[0069] According to the present invention, a non-destructive testing device for the uniformity of internal quality distribution of watermelon is provided, wherein the photodetector is a photomultiplier tube, and the retractable black rubber light-shielding sleeve is an accordion-shaped retractable structure used to adapt to changes in the surface distance between the photomultiplier tube and the watermelon being tested.

[0070] refer to Figure 6 , Figure 6 This is a schematic diagram of the structure of the photodetector and the light-shielding sleeve provided by the present invention.

[0071] Figure 6 The image shows a photodetector and a retractable black rubber light-shielding sleeve. The photodetector uses a photomultiplier tube, which has advantages such as wide sensing range, high sensitivity, and low cost. A retractable accordion-shaped black rubber sleeve is designed at the end of the photodetector to adapt to changes in the distance between the photodetector and the watermelon, always maintaining a close contact with the watermelon surface to prevent stray light from entering.

[0072] This invention employs a multi-angle acquisition scheme. By acquiring light signals from multiple angles and directions, it expands traditional single-point light intensity acquisition into three-dimensional spatial acquisition, designing a three-dimensional array of photoelectric sensors distributed around the watermelon. Light from different angles carries different internal structural information; comprehensive analysis of these signals yields more complete internal structural information, effectively improving imaging resolution and accuracy, and providing strong support for accurately presenting the sugar content and firmness distribution inside the watermelon.

[0073] According to the present invention, a non-destructive testing device for the uniformity of internal quality distribution of watermelon, comprising an electric opening and closing mechanism, includes:

[0074] The linear module includes a stepper motor and a lead screw slide. The lead screw slide includes a lead screw with a positive and negative thread structure. The lead screw is divided by the central axis, with the left half having a positive thread and the right half having a negative thread.

[0075] The first slider and the second slider are respectively fitted on the positive thread and the negative thread; the output shaft of the stepper motor is coaxially connected to the lead screw. When the lead screw rotates clockwise, it drives the first slider and the second slider to move towards each other to achieve a closing action. When the lead screw rotates counterclockwise, it drives the two sliders to move away from each other to achieve an opening action.

[0076] refer to Figure 7 , Figure 7 This is a structural diagram of the electric opening and closing mechanism provided by the present invention.

[0077] The electric opening and closing mechanism is responsible for driving the opening and closing of the optical detection device. Figure 7 As shown, the linear module consists of two parts: a lead screw and a slide table linear module, and a stepper motor. The lead screw transmits motion through a lead screw, typically a spur or reverse lead screw. This invention combines both, using a spur and reverse lead screw design, with the left half of the lead screw being spur and the right half reverse. This design allows the two sliders to move towards the center when the lead screw rotates clockwise and to move to both sides when it rotates counterclockwise, achieving synchronous opening and closing. The linear module has a single-sided travel of 100 mm, a lead screw diameter of 16 mm, and a lead of 5 mm, ensuring sufficient opening and closing speed for the sliders. The stepper motor is connected to the linear module via a coupling and drives the linear module. A 57 stepper motor with a torque of 1.3 Nm is used.

[0078] refer to Figure 8 , Figure 8 This is a schematic diagram of the fruit holder provided by the present invention.

[0079] Fruit tray structure such as Figure 8 As shown, a certain depth of recess is designed at the top of the fruit holder to make the watermelon more stable when placed, and a door-shaped groove is opened at the bottom for cross-shaped installation with the electric opening and closing mechanism.

[0080] refer to Figure 9 , Figure 9 The overall structure of the diffused light three-dimensional acquisition module provided by this invention includes: an LED combination light panel, a light shield, a photomultiplier tube, a stepper motor, a forward and reverse toothed linear slide, and a fruit holder.

[0081] The complete watermelon three-dimensional multispectral acquisition module, consisting of a photoelectric acquisition module, an electric opening and closing module, and a fruit holder, is shown in the structural diagram below. Figure 9 As shown, two photoelectric acquisition modules are mounted on the slider of the electric opening and closing module, and the fruit holder is placed in the middle of the slide table, forming a stable cross base with the electric slide table.

[0082] According to the present invention, a non-destructive testing device for the uniformity of internal quality distribution of watermelon is provided. The light source wavelength combination includes a sensitive band of 1000-1400nm and a reference band of 700-750nm for sugar content detection, and a high absorption band of 850-1000nm for moisture content detection.

[0083] In related technologies, the size difference of watermelons can affect the shape and intensity of their spectra, which in turn affects the accuracy of predicting the internal quality of watermelons.

[0084] In predicting the internal quality of watermelons using spectral technology, the significant differences in watermelon size directly affect the shape and intensity of the spectrum. From an optical perspective, watermelons of different sizes have different internal material distributions and light propagation paths. When light passes through a watermelon, larger watermelons travel a longer distance and encounter more scattering and absorption than smaller ones. This results in differences in the shape and intensity of the reflected or transmitted spectra from watermelons of different sizes, thus significantly impacting the accuracy of predicting the watermelon's internal quality.

[0085] In this embodiment of the invention, a high absorption band of 850-1000 nm for components such as moisture and sugar is selected, combined with a band of 700-750 nm that is less affected by volume. Sensitive and reference band combinations: A band sensitive to the sugar content of the fruit pulp (e.g., 1000–1400 nm) is selected and combined with a band relatively unaffected by volume to obtain a light source wavelength combination. By calculating the ratio or difference of these bands, the influence of volume differences can be effectively eliminated.

[0086] Specifically, this includes data acquisition and wavelength selection. For example, spectral data from over 100 watermelon samples of different volumes are collected, covering a range of volumes. Wavelengths highly correlated with sugar content are selected as quality-sensitive wavelengths and combined with bands highly correlated with water absorption.

[0087] This invention eliminates systematic errors caused by volume differences by selecting different wavelength combinations. By selecting wavelengths where the signal intensity shows a stable relationship with volume when light passes through watermelons with varying internal sugar content, a base reference is used to calibrate the changing optical path. Specifically, this involves combining a sensitive wavelength corresponding to the soluble solids content that determines watermelon quality with a reference wavelength for water content, which is highly correlated with watermelon volume. This combination effectively eliminates or significantly reduces systematic errors caused by watermelon volume differences. Utilizing the high-response characteristics of the sensitive wavelength based on watermelon sugar content, and leveraging the stable characteristics of the reference wavelength for watermelon moisture content, the comparison of these two effectively eliminates interference factors caused by volume differences, thereby significantly improving the accuracy of predicting the internal quality of watermelons.

[0088] refer to Figure 10 , Figure 10 This is a schematic diagram of the basic method for detecting the sugar content and firmness distribution inside a watermelon provided by the present invention. It includes: a multi-wavelength visible-near-infrared light source (emitting near-infrared light of different wavelengths to penetrate the fruit), a photodetector matrix (receiving transmitted light signals inside the fruit), a data acquisition and control system (signal acquisition, preprocessing and control of the light source), a reconstruction algorithm and signal processing (reconstruction and processing based on diffusion method), and data visualization and output (generating a three-dimensional sugar content distribution image).

[0089] The basic method and procedure for detecting the internal sugar content and firmness distribution of watermelon are as follows: Figure 10 As shown, a multi-wavelength visible and near-infrared light source emits near-infrared light of different wavelengths in sequence, which penetrates the watermelon. A photodetector array distributed around the watermelon skin receives the transmitted light signal from inside the watermelon. The microprocessor performs signal acquisition, preprocessing, and light source control, and reconstructs sugar content and quality based on the watermelon tissue diffusion equation. Finally, the results are visualized to generate a three-dimensional sugar content distribution image.

[0090] In related technologies, for thin-skinned fruits such as apples and pears, the influence of the peel on the overall spectral characteristics of the fruit is usually negligible. However, the situation is quite different for watermelons, which are thick-skinned fruits. When using transmission spectroscopy alone to detect the internal quality of a watermelon, the light needs to penetrate the entire watermelon, including the peel which has strong spectral absorption. Therefore, the transmission spectral signal is significantly interfered with by the peel and cannot accurately reflect the true condition inside the watermelon. Furthermore, reflectance spectroscopy mainly reflects the characteristics of the watermelon's surface, i.e., the peel, and is insufficient to obtain adequate internal information.

[0091] Using transmission spectra alone is affected by the peel, while reflectance spectra reflect the peel's characteristics more comprehensively. This invention, by combining transmission and reflectance spectra, can obtain more comprehensive internal and external information about the watermelon, thus helping to correct for the peel's influence. The photoelectric signal collected by the photodetector on each light panel is the reflected signal, and the photoelectric signal collected by the photodetector opposite along the diameter direction is the transmission signal. After the 18 light panels are sequentially turned on and off, the photoelectric acquisition system obtains 18 sets of reflectance and transmission spectra. Using the ratio of the reflectance spectrum to the transmission spectrum as the input value of the prediction model can reduce the influence of the peel in the transmission spectrum. The formula for calculating the ratio of the reflectance spectrum to the transmission spectrum is:

[0092]

[0093] in, Represents the intensity of the reflected spectral signal, which reflects the watermelon rind surface's ability to reflect light of different wavelengths and its related optical properties; This represents the intensity of the transmission spectrum signal, which contains information carried by light after it penetrates the internal tissues of the watermelon, but is affected by factors such as absorption by the peel. By calculating the ratio of the two, the influence of peel absorption characteristics can be eliminated or weakened to some extent, allowing subsequent watermelon internal quality prediction models based on this ratio to more accurately reflect the true quality status of the watermelon's interior, such as key indicators like sugar content and firmness distribution.

[0094] This invention proposes a scheme that combines transmission and reflectance spectroscopy to eliminate the influence of the rind on the prediction of watermelon's internal quality. By simultaneously acquiring transmission and reflectance spectra, more comprehensive information about the watermelon's internal and external structure can be obtained. The transmission spectrum carries information about light penetrating the watermelon's internal tissues, while the reflectance spectrum reflects the characteristics of the watermelon's surface, including the rind. Combining the two and using data analysis algorithms, the influence of the rind on the spectrum can be analyzed, and interfering components from the rind can be effectively removed from the overall spectral information, thereby correcting the rind's influence and providing a reliable data foundation for accurately predicting the watermelon's internal quality.

[0095] In related technologies, NIR and DOT technologies provide spectral information and three-dimensional imaging data, respectively. How to effectively integrate these two types of data to comprehensively reflect the quality distribution of sugar content and firmness inside a watermelon is an important technical challenge.

[0096] The three-dimensional sugar content inversion model of watermelon is constructed based on the theory of diffuse light tomography, and includes three main parts: photon transport model (forward problem), image reconstruction technology (inverse problem), and diffuse light measurement system.

[0097] DOT image reconstruction is an inverse problem: formally defined as follows: given the spatiotemporal distribution of the light source on the tissue surface and the corresponding spatiotemporal distribution of the transmitted light measurements, based on a specific photon transport model, solve for the three-dimensional distribution of optical parameters within the tissue. The task of DOT imaging is to simultaneously reconstruct the distribution of all optical parameters within the tissue domain. However, in applications, it is often assumed that one or two parameter distributions (usually the refractive index) are known constants to simplify the solution; that is, usually only the absorption coefficient and the reduced scattering coefficient are reconstructed. If random noise effects are not considered, image reconstruction can be represented by a nonlinear least-squares optimization problem, with commonly used methods such as the Newton-Raphson method, an image reconstruction technique based on forward model linearization.

[0098] The implementation of DOT requires measuring the optical flow distribution (generally considered as projection) at other points on the lower surface under multi-point excitation (generally considered as multi-angle scanning). Direct contact with optical fibers or spatial light can be used for light projection and reception. Currently, diffused light measurement systems mainly have three modes: time-resolved measurement mode, continuous light measurement mode, and frequency domain measurement mode.

[0099] A forward model based on the diffusion equation is used to simulate the propagation of light inside a watermelon. Watermelons are typically complex geometries with non-uniform optical parameter distributions, while analytical solutions to the diffusion equation can only be obtained in tissues with regular geometries and uniform optical parameter distributions. Therefore, this invention employs the finite element method based on the diffusion equation for numerical solution. The forward model can be customized according to the size and shape of the watermelon to improve the accuracy of the reconstruction results.

[0100] The main steps of the diffusion equation: emissivity mentioned in radiative transfer theory... Scattering phase function and light source items Expand using spherical harmonics. The three-term time-domain expansion is as follows:

[0101]

[0102] In the formula, Indicates emissivity, indicating the location ,direction ,time The distribution of emitted light energy Indicates the internal mode of order, Indicates the order, It is a spherical harmonic function; For expansion coefficients, This represents the scattering phase function, describing the direction of photon scattering. Scattered to direction The probability distribution, Represents the Legendre expansion coefficients. Represents the complex conjugate of a spherical harmonic function. Indicates the light source item. The spherical harmonic expansion coefficient represents the directionality of a light source. This represents the normalization factor, ensuring the orthogonality of spherical harmonic functions.

[0103] A low-order expansion of the radiation equation yields the time-domain diffusion equation as follows:

[0104]

[0105]

[0106] The diffusion coefficient is:

[0107]

[0108] Reduced scattering coefficient:

[0109]

[0110] in, Represents photon energy density. Indicates the diffusion coefficient. Indicates the absorption coefficient. For the reduced scattering coefficient, For anisotropy factor, At the speed of light, This is an isotropic light source term.

[0111] When measuring watermelon tissue, based on the temporal and spatial distribution of incident light (source term) and outgoing light (detector term), the calculated value is infinitely close to the measured value by repeatedly solving the forward problem of light propagation, thereby reversing the distribution of optical parameters such as absorption coefficient and scattering coefficient inside the tissue.

[0112] After sequentially acquiring data from five wavelength light sources, the spatiotemporal distribution of the light source on the surface of the watermelon tissue and the corresponding spatiotemporal distribution of the downtransmitted light were obtained. Based on the photon transport model, the three-dimensional distribution of optical parameters corresponding to the five different wavelengths of light within the tissue was solved. The absorption and scattering coefficients were inverted using a nonlinear iterative method (Levenberg-Marquardt method), and the sugar content distribution at different depths of the watermelon was reconstructed based on a traditional sugar content and firmness regression model. To avoid noise amplification and errors introduced by ill-posed data, the Tikhonov regularization method was employed to ensure the smoothness and physical meaning of the reconstructed sugar content distribution.

[0113] This invention proposes a tissue optical diffusion model for watermelons, develops a data fusion algorithm integrating NIR spectral data and DOT imaging data, and extracts comprehensive features. Three-dimensional sugar content and quality are then determined from the collected data.

[0114] The uniformity of sugar content and firmness distribution within watermelons was graded based on the coefficient of variation. The formulas for calculating the coefficients of variation for sugar content and firmness are:

[0115]

[0116] in, It is the standard deviation of sugar content or hardness at each point; It is the average of the sugar content or hardness at each point.

[0117] The formula for calculating the average is:

[0118]

[0119] Where N is the total number of data points for sweetness or hardness. It is the sugar content or hardness value of the i-th point.

[0120] The formula for calculating the standard deviation is:

[0121]

[0122] in It is the sugar content or hardness value at the i-th point. This represents the average sugar content or hardness.

[0123] Sugar content and hardness distribution uniformity are each divided into three grades, with grade 1 having the highest uniformity, grade 2 the next highest, and grade 3 the lowest. The grading criteria are as follows:

[0124]

[0125] Considering that the sugar content uniformity and firmness uniformity of watermelons are not uniform, this invention takes into account both sugar content uniformity and firmness uniformity to establish an overall uniformity index for the internal quality of watermelons, which is divided into 5 levels, with level 1 having the highest overall uniformity and level 5 having the lowest overall uniformity. The grading standards are shown in Table 1.

[0126] Table 1 Grading Standards for Overall Uniformity of Watermelon Internal Quality

[0127]

[0128] The following describes an example of the non-destructive testing device for the uniformity of watermelon internal quality distribution provided by this invention in a practical application scenario. Specifically, it includes the following steps:

[0129] Step 1, Watermelon Placement: Place the watermelon on the detection platform, and adjust the distance between the light source and detector and the watermelon surface according to the size of the watermelon to ensure detection effect.

[0130] Step 2, Multi-wavelength three-dimensional distributed light intensity detection: After the system is started, multi-wavelength near-infrared light sources emit light in sequence, and the detector array synchronously collects light signals passing through the watermelon at different angles and depths to obtain detection data.

[0131] Step 3, Data Preprocessing: The acquired optical signal enters the data acquisition module and undergoes real-time preprocessing operations such as noise cancellation and signal amplification to improve data quality.

[0132] Step 4, Reconstructing Sugar Content and Firmness Distribution: The preprocessed signal is input into the reconstruction algorithm, and after solving the forward model and inverse problem, the absorption and scattering coefficient distribution of watermelon at different depths is reconstructed. Then, the specific sugar content distribution is inferred based on the light absorption characteristics.

[0133] Step 5, Visualization and Output: Generate and display a three-dimensional sugar content and firmness distribution map inside the watermelon in real time. At the same time, the system generates a quality report to present the test results intuitively.

[0134] refer to Figure 11 , Figure 11This is a schematic diagram illustrating application scenarios of the watermelon internal quality distribution detector provided by the present invention, including: (A) Application scenario 1: desktop detection equipment; (B) Application scenario 2: watermelon in-situ detection robot end effector.

[0135] The detection device of this invention has two main application scenarios. Firstly, application scenario 1: it can be used as a stand-alone desktop device, suitable for testing watermelon quality in fixed locations such as laboratories and warehouses (e.g., Figure 11 (A) shown). Secondly, application scenario 2: The device base is installed on the robotic arm as an end effector, which can realize in-situ detection during the growth of watermelons in the orchard and provide real-time data (such as...). Figure 11 (As shown in (B)).

[0136] refer to Figure 12 , Figure 12 This is a schematic diagram of the closed state of the three-dimensional multispectral acquisition module provided by the present invention.

[0137] refer to Figure 13 , Figure 13 This is a schematic diagram showing the powered-on state of the three-dimensional multispectral acquisition module provided by the present invention.

[0138] This invention enables non-destructive testing of watermelons before harvesting, ensuring that the sugar content and firmness of each watermelon meet preset standards. The test results are displayed in real time, helping farmers select high-quality watermelons and improve market competitiveness and economic benefits. Analysis of the sugar content and firmness distribution of different watermelon varieties can identify superior genes with uniform sugar content, high sweetness, and moderate firmness, guiding the improvement of watermelon varieties and cultivation, and accelerating the breeding of new high-quality watermelon varieties.

[0139] The above embodiments of the present invention achieve at least the following technical effects:

[0140] This invention enables the three-dimensional spatial distribution measurement of sugar content in watermelons. Utilizing the scattering and absorption characteristics of near-infrared light in watermelons, the multi-wavelength absorption properties of near-infrared light, and optimized detector arrangement, combined with a diffusion optical tomography reconstruction algorithm, it achieves non-destructive testing of the sugar content and firmness distribution at different depths within the watermelon.

[0141] The light source structure is rationally designed. This invention arranges multi-wavelength LED light sources in a ring, ensuring uniform light exposure for the watermelon while dispersing heat to prevent burns to the watermelon's skin. The ring light sources are individually controlled to turn on and off in turn according to wavelength, enabling a single device to collect optical diffusion information at multiple wavelengths.

[0142] Effective stray light control. This invention effectively avoids interference from ambient light by designing an openable, contour-following miniature darkroom. Inside the miniature darkroom, each photodetector is equipped with a compressible black rubber light-shielding tube at its end, which can adapt to different distances between the photodetector and the watermelon rind, preventing light crosstalk near the photodetector.

[0143] Diverse application scenarios. This invention designs the photoelectric acquisition module to open and close from left to right, and uses a linear mechanism with positive and negative teeth for electrically controlled opening and closing. This allows the instrument to be used not only as a tabletop device, but also as an end effector mounted on a robotic arm to perform in-situ detection of watermelons on branches, meeting the needs of different agricultural production.

[0144] The following describes the non-destructive testing method for the uniformity of internal quality distribution of watermelon provided by the present invention. The non-destructive testing method for the uniformity of internal quality distribution of watermelon described below can be referred to in correspondence with the non-destructive testing device for the uniformity of internal quality distribution of watermelon described above.

[0145] The photoelectric signal of the watermelon under test is collected by a preset combination of light source wavelengths to obtain the transmitted light signal.

[0146] Based on the transmitted light signal, the three-dimensional distribution of watermelon sugar content and watermelon hardness is inverted to obtain the watermelon detection signal;

[0147] Based on the watermelon detection signal, a three-dimensional sugar content and firmness distribution map corresponding to the tested watermelon is generated and displayed.

[0148] Specifically, the non-destructive testing method for the uniformity of internal quality distribution of watermelon provided by the present invention can realize all the method steps implemented in the embodiment of the non-destructive testing device for the uniformity of internal quality distribution of watermelon, and can achieve the same technical effect. Here, the parts that are the same as those in the method embodiment and the beneficial effects will not be described in detail.

[0149] Figure 14 This is a schematic diagram of the physical structure of the electronic device provided by the present invention, such as... Figure 14As shown, the electronic device may include: a processor 1410, a communication interface 1420, a memory 1430, and a communication bus 1440. The processor 1410, communication interface 1420, and memory 1430 communicate with each other via the communication bus 1440. The processor 1410 can call logic instructions in the memory 1430 to execute a non-destructive testing method for the uniformity of the internal quality distribution of a watermelon. This method includes: acquiring photoelectric signals from the watermelon under test using a preset combination of light source wavelengths to obtain a transmitted light signal; performing a three-dimensional inversion of the watermelon's sugar content and hardness distribution based on the transmitted light signal to obtain a watermelon detection signal; generating and displaying a three-dimensional sugar content and hardness distribution map corresponding to the watermelon under test based on the watermelon detection signal.

[0150] Furthermore, the logical instructions in the aforementioned memory 1430 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0151] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the non-destructive testing method for the uniformity of internal quality distribution of watermelon provided by the above methods. The method includes: acquiring photoelectric signals of the watermelon under test through a preset combination of light source wavelengths to obtain a transmitted light signal; performing a three-dimensional inversion of the sugar content and hardness distribution of the watermelon based on the transmitted light signal to obtain a watermelon detection signal; generating a three-dimensional sugar content and hardness distribution map corresponding to the watermelon under test based on the watermelon detection signal, and displaying the three-dimensional sugar content and hardness distribution map.

[0152] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon. When executed by a processor, the computer program implements a non-destructive testing method for the uniformity of internal quality distribution of watermelon provided by the above methods. The method includes: acquiring photoelectric signals from the watermelon under test using a preset combination of light source wavelengths to obtain a transmitted light signal; performing a three-dimensional inversion of the sugar content and hardness distribution of the watermelon based on the transmitted light signal to obtain a watermelon detection signal; generating a three-dimensional sugar content and hardness distribution map corresponding to the watermelon under test based on the watermelon detection signal, and displaying the three-dimensional sugar content and hardness distribution map.

[0153] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0154] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0155] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A non-destructive testing device for the uniformity of internal quality distribution in watermelons, characterized in that, include: The three-dimensional multispectral acquisition module is used to acquire photoelectric signals from the watermelon under test by using a preset combination of light source wavelengths to obtain transmitted light signals. The signal acquisition and control circuit is communicatively connected to the three-dimensional multispectral acquisition module and is used to drive the three-dimensional multispectral acquisition module in response to the control signal. The microprocessor is communicatively connected to the signal acquisition and control circuit and the three-dimensional multispectral acquisition module, respectively. It is used to send the control signal to the signal acquisition and control circuit and receive the transmitted light signal transmitted by the three-dimensional multispectral acquisition module. Based on the transmitted light signal, it performs three-dimensional distribution inversion of watermelon sugar content and watermelon hardness to obtain watermelon detection signal. The display module is communicatively connected to the microprocessor and is used to receive the watermelon detection signal transmitted by the microprocessor, generate a three-dimensional sugar content and hardness distribution map of the tested watermelon based on the watermelon detection signal, and display the three-dimensional sugar content and hardness distribution map. The power supply module is electrically connected to the signal acquisition and control circuit, the microprocessor, and the display module, respectively, and is powered by an AC 220V to DC 24V switching power supply. The three-dimensional multispectral acquisition module includes: a photoelectric acquisition module, an electric opening and closing mechanism, and a fruit holder; The photoelectric acquisition module is installed on the electric opening and closing mechanism, which is used to open or close the photoelectric acquisition module. The photoelectric acquisition module is used to collect the transmission spectrum and reflection spectrum of the watermelon under test in a closed detection space. The fruit holder is installed in the middle of the electric opening and closing mechanism, forming a cross base with the electric opening and closing mechanism; The photoelectric acquisition module includes: The multi-wavelength ring light source is composed of multiple multi-wavelength light-emitting diode (LED) panels arranged in a ring. Each multi-wavelength LED panel integrates multiple wavelength LEDs, and each wavelength LED is equipped with multiple LED beads. The multiple LED beads are arranged in a preset row and column number, and the multiple LED beads of each wavelength are independently controlled to turn on and off. The photoelectric detector assembly includes multiple photoelectric detectors distributed along the latitude direction and multiple photoelectric detectors distributed along the longitude direction, forming a transmitted light signal acquisition array with a preset number of rows and columns. The ends of the photoelectric detectors are equipped with retractable black rubber light-shielding sleeves to fit the surface of the watermelon being tested. The contoured micro anechoic chamber is symmetrically divided into two half-shells. The side walls of the contoured micro anechoic chamber are provided with a light source mounting area and upper and lower photodetector mounting areas. The light source mounting area is used to install the multi-wavelength ring light source, and the upper and lower photodetector mounting areas are used to install the photodetector assembly. Light-shielding partitions are set on both sides of the light source mounting area to limit the illumination angle to 0 degrees. The upper and lower photodetector mounting areas are respectively arranged with photodetector slots of a preset number of rows and columns.

2. The non-destructive testing device for the uniformity of internal quality distribution of watermelon according to claim 1, characterized in that, The photodetector is a photomultiplier tube, and the retractable black rubber light-shielding sleeve is an accordion-shaped retractable structure used to adapt to changes in the surface distance between the photomultiplier tube and the watermelon being tested.

3. The non-destructive testing device for the uniformity of internal quality distribution of watermelon according to claim 1, characterized in that, The contoured micro anechoic chamber is closed by the two semi-shells to form a closed detection space. The closed detection space is a complete hollow cylinder used to shield against environmental stray light interference.

4. The non-destructive testing device for the uniformity of internal quality distribution of watermelon according to claim 1, characterized in that, The electric opening and closing mechanism includes: A stepper motor and a linear module with a lead screw slide, wherein the linear module with a lead screw has a positive and negative thread structure, and the lead screw is machined with a positive thread on the left half and a negative thread on the right half with the central axis as the boundary; The positive and negative threads are respectively equipped with a first slider and a second slider; the output shaft of the stepper motor is coaxially connected to the lead screw. When the lead screw rotates clockwise, it drives the first slider and the second slider to move towards each other to achieve a closing action. When the lead screw rotates counterclockwise, it drives the two sliders to move away from each other to achieve an opening action.

5. The non-destructive testing device for the uniformity of internal quality distribution of watermelon according to claim 1, characterized in that, The light source wavelength combination includes a sensitive band of 1000-1400nm and a reference band of 700-750nm for sugar content detection, and a high absorption band of 850-1000nm for moisture content detection.

Images