A near-infrared detection device for sugar content and acidity of apples

Abstract

The utility model discloses a kind of apple sugar content and acidity near-infrared detection device, including instrument shell, the shock absorber is fixedly arranged in the bottom four corners of instrument shell, sample introduction conveying mechanism, positioning adjusting mechanism, spectral acquisition system and industrial computer control system are integrally arranged in the inside of instrument shell, the sample introduction conveying mechanism includes the conveying belt that is horizontally arranged along the length direction of instrument shell, conveying roller is rotatably supported in the conveying belt both sides, drive motor is fixedly installed in the conveying belt one end side, the output shaft of drive motor is connected with the transmission of conveying roller's rotating shaft by coupling, the utility model automatically transports apple by conveying belt, positioning mechanism is adjusted to apple equator line and multi-angle rotation, spectral system gathers near-infrared signal, industrial computer controls whole process and processes data, realizes apple sugar acid synchronous nondestructive testing, automatically reduces error, precision is high, adapts industrialization batch detection demand.

Description

Technical Field

[0001] This utility model relates to the field of agricultural product quality testing technology, specifically to a near-infrared detection device for apple sugar content and acidity. Background Technology

[0002] As one of the world's highest-producing and most widely consumed temperate fruits, apples had a global annual production exceeding 80 million tons in 2023. China, as the main producing country, accounted for over 50% of this production. Apples' internal quality indicators, such as sugar content and acidity (measured by malic acid content), not only directly determine the fruit's flavor and taste but also serve as core criteria influencing consumer purchasing intentions, supermarket pricing, and export trade grades. With the trend of consumption upgrading and the increasing emphasis on the quality of agricultural products, the market's demand for accurate evaluation of apple quality is becoming increasingly urgent. Efficient and non-destructive quality testing technologies have become a key support for the apple industry chain, from post-harvest sorting to final quality control.

[0003] Traditional methods for testing the sugar and acidity of apples primarily rely on chemical analysis. These methods include: using a handheld saccharimeter to measure sugar content requires juicing the apples and collecting the supernatant for testing, consuming 5-10 mL of juice per test – a typical destructive sampling method. Furthermore, sugar oxidation during juicing can easily lead to errors. Using acid-base titration to determine acidity requires homogenizing and filtering the pulp before titration, taking 6-30 minutes per test – extremely inefficient and unable to meet the demands of production lines requiring "dozens per minute." It also requires the use of chemical reagents such as phenolphthalein indicators, posing risks of reagent contamination and operational safety. In addition, traditional methods are limited by sampling limitations, failing to reflect the differences in sugar and acid distribution in different parts of the fruit. This results in test results that do not represent the overall quality of the apples, easily leading to misclassification and causing economic losses for fruit growers and businesses.

[0004] Near-infrared spectroscopy, with its advantages of being non-destructive, rapid, environmentally friendly, and enabling simultaneous detection of multiple components, has become the mainstream technology in the field of agricultural product quality testing, and related patented technologies are gradually emerging, such as: Patent application number 201611112269.4 and publication number CN105527244A discloses a fruit sugar content detection device based on near-infrared spectroscopy. It adopts a wavelength range of 500-1900nm and focuses on improving the accuracy of the detection model by improving the linear regression algorithm. However, the device has two major defects: First, the wavelength range does not cover the characteristic peak of apple acidity, so it cannot detect acidity. Second, the model calculation relies on complex advanced algorithms, and the calculation of a single sample takes more than 2 minutes. It is only suitable for laboratory sampling analysis and cannot meet the real-time requirements of industrial online detection. In addition, the device requires manual adjustment of the sample position, making the operation process cumbersome.

[0005] Although the patents with application numbers 201710121615.3 and 201710271814.2 optimized the spectral acquisition structure based on the aforementioned patents, they still failed to overcome the limitations of "single component detection" and "low automation": the former can only detect sugar content, and the latter requires manual assistance to position the apples, with a detection capacity of less than 50 per hour, far below the requirement of "more than 300 per hour" for large-scale production lines. Furthermore, they do not have an angle adjustment mechanism and can only collect the spectrum of a single surface of the apple, which cannot avoid detection deviations caused by differences in fruit parts.

[0006] The patent with publication number CN1430723A uses a combination of multispectral analyzers to collect spectral signals from 250 to 1150 nm, with a tungsten filament lamp as the light source. However, the device has a complex structure: the use of multispectral analyzers increases the cost of the equipment by more than 40% compared to a single spectrometer, and the spectral intensity stability of the tungsten filament lamp is poor, resulting in poor repeatability of the spectral signal and a sugar content detection error of more than 1.5 Brix. At the same time, the device does not integrate a sample loading and delivery mechanism, requiring manual loading of samples one by one, which is inconvenient to operate and prone to human error.

[0007] The patent with publication number CN119869969B focuses on sugar content sorting of Sanhua plums. It uses the 400-1100nm visible-near infrared band. However, the tissue structure and sugar-acid composition of Sanhua plums and apples are significantly different. The wavelength range, light source power and detection model of this device are not suitable for apples. If it is forcibly applied, the sugar content detection error of apples will exceed 2 Brix and the acidity detection error will exceed 0.2%, which cannot meet the requirements for accurate detection.

[0008] In summary, current near-infrared spectroscopy (NIRS) detection technology still faces the following pressing issues in detecting the sugar and acidity of apples: Both destructive and inefficient: Traditional chemical methods require sampling and damaging the fruit, while near-infrared devices are non-destructive, but some patents (such as 201611112269.4) have low detection efficiency and are complicated to operate, making them unsuitable for industrial production lines. Insufficient comprehensiveness of testing: Most devices only detect sugar content or the spectrum of a single part of the fruit (such as CN1430723A), ignoring acidity detection and differences in fruit parts, resulting in incomplete quality evaluation; Low level of automation: It lacks integrated sample introduction, positioning, and angle adjustment mechanisms (such as 201710121615.3), requires manual intervention, is prone to introducing errors, and has a low detection volume; Poor accuracy and stability: Some devices have wavelength range mismatch with malic acid characteristic peaks, insufficient light source stability (such as tungsten filament lamps), or poor model adaptability (such as CN119869969B), resulting in large detection errors and low repeatability. Utility Model Content

[0009] The purpose of this invention is to provide a near-infrared detection device for apple sugar content and acidity, in order to solve the problems of destructiveness and low efficiency, insufficient detection comprehensiveness, low degree of automation, and poor accuracy and stability in the existing apple detection technology mentioned in the background art.

[0010] To achieve the above objectives, this utility model provides the following technical solution: a near-infrared detection device for apple sugar content and acidity, comprising an instrument housing, wherein shock absorbers are fixedly installed at the four corners of the bottom of the instrument housing, and the instrument housing integrates a sample delivery mechanism, a positioning adjustment mechanism, a spectral acquisition system, and an industrial control computer control system. The sample delivery mechanism includes a conveyor belt arranged horizontally along the length of the instrument housing. Conveyor rollers are rotatably supported on both sides of the conveyor belt. A drive motor is fixedly installed on one side of the conveyor belt. The output shaft of the drive motor is connected to the rotating shaft of the conveyor roller through a coupling. The positioning adjustment mechanism is set at the other end of the conveyor belt, including a lifting platform and a rotating platform horizontally located on the top surface of the lifting platform. A connecting seat is fixed at the center of the bottom of the lifting platform. The connecting seat is fixedly connected to a lead screw sleeve. A lead screw is threaded inside the lead screw sleeve. The bottom of the lead screw is connected to the output shaft of the lifting motor. Limiting vertical rods are set on the outer sides of the four corners of the lifting platform. The limiting vertical rods are vertically fixed to the rear side of the instrument housing through vertical rod L-shaped brackets. The spectral acquisition system is positioned directly above the rotating platform and includes a light source, a broadband halogen lamp, a spectral alignment box, a near-infrared spectrometer main unit, a CCD camera, and a fiber optic probe. The broadband halogen lamp is connected to the spectral alignment box via a broadband fiber optic cable, and the fiber optic probe is connected to the near-infrared spectrometer main unit via armored fiber optic cable. The light source, broadband halogen lamp, CCD camera, and fiber optic probe are all horizontally fixed inside the instrument housing above the instrument via a bracket, and the central axes of the four are located on the same horizontal plane. The CCD camera is located between the broadband halogen lamp and the fiber optic probe, and the light source and broadband halogen lamp are arranged adjacent to each other. The industrial control system includes an industrial computer, a control module, and a data acquisition card. A mounting plate is vertically fixed inside the rear side of the instrument housing. The industrial computer, control module, and data acquisition card are all fixed on the mounting plate. The industrial computer is electrically connected to the control module and the data acquisition card, respectively. The control module is electrically connected to the drive motor and the lifting motor, respectively.

[0011] As a preferred embodiment of this utility model, a through groove along the width direction of the conveyor belt is provided at one end of the conveyor belt near the positioning adjustment mechanism. A photoelectric sensor is fixedly installed on the side of the through groove away from the positioning adjustment mechanism by an L-shaped bracket. The detection end of the photoelectric sensor is horizontally oriented towards the conveying surface of the conveyor belt. The photoelectric sensor is electrically connected to a data acquisition card. The output shaft of the drive motor and the rotating shaft of the conveyor roller are coaxially driven by an elastic coupling to ensure transmission stability.

[0012] As a preferred technical solution of this utility model, a displacement sensor is vertically fixed on the side of the lifting platform away from the rotating platform by a displacement sensor bracket. The detection end of the displacement sensor is horizontally facing the side of the lifting platform. The displacement sensor is electrically connected to the data acquisition card. A connecting lifting frame is detachably installed on the outer wall of the lifting platform by fastening bolts. A vertical lifting groove is opened on the inner wall of the limiting vertical rod. The end of the connecting lifting frame away from the lifting platform is slidably embedded in the lifting groove.

[0013] As a preferred embodiment of this utility model, a rotating connecting rod is vertically fixed at the center of the bottom of the rotating platform. The rotating connecting rod passes through the central through hole of the lifting platform and is connected to the output shaft of the stepper motor via a synchronous belt. The stepper motor is fixed in the cavity inside the lifting platform by a motor bracket. An angle sensor is fixed on the lifting platform on the side of the rotating platform by a triangular bracket. The detection end of the angle sensor faces the edge groove of the rotating platform. The angle sensor is electrically connected to the data acquisition card. The control module is electrically connected to the stepper motor.

[0014] In a preferred embodiment of this invention, the light source and the broadband halogen lamp work together as a detection light source, the fiber optic probe and the broadband halogen lamp are at a horizontal angle, the CCD camera and the broadband halogen lamp are at a horizontal angle, and the CCD camera is electrically connected to the control module.

[0015] As a preferred technical solution of this utility model, a human-machine interface is embedded and installed on the front surface of the instrument shell. The human-machine interface is electrically connected to an industrial control computer. The data acquisition card is electrically connected to a displacement sensor, an angle sensor, and a photoelectric sensor, respectively. The control module is also electrically connected to a broadband halogen lamp, a light source, and a CCD camera, respectively.

[0016] As a preferred technical solution of this utility model, there are four limiting vertical rods, which correspond to the four outer corners of the lifting platform respectively, and the axes of the four limiting vertical rods are distributed in a rectangular shape. The length of the lifting groove is adapted to the maximum lifting stroke of the lifting platform.

[0017] Compared with the prior art, the beneficial effects of this utility model are: 1. By employing near-infrared spectroscopy technology, a spectral acquisition system, a broadband halogen lamp, a light source, a fiber optic probe, and a near-infrared spectrometer host are used to collect diffuse reflectance spectral signals from the surface of apples. This eliminates the need for destructive operations such as juicing or homogenization; sugar content and acidity can be determined solely through light signal analysis, preventing fruit damage. A sample feeding and conveying mechanism, with a conveyor belt and drive motor under closed-loop control by an industrial control computer, automatically transports the apples to be tested to the designated area. A photoelectric sensor triggers the system to stop when the apples are in position. Subsequent lifting, spectral acquisition, and data processing require no manual intervention. Furthermore, the conveyor belt speed is matched to the testing cycle, replacing the destructive sampling of traditional chemical methods. Apples can still be sold and stored normally after testing. The testing efficiency is significantly improved compared to existing manually assisted near-infrared devices, meeting the industrial-scale batch testing needs of apple processing plants and supermarkets for grading. This addresses the pain points of destructive sampling and inefficient testing, achieving non-destructive, industrial-scale batch testing of apples. 2. By designing a light source and a broadband halogen lamp synergistic light-emitting module, the effective spectral range covers the wavelength range, including both the characteristic response band of sugar and the characteristic peak of malic acid. In conjunction with the near-infrared spectrometer host, it synchronously collects the spectral signals corresponding to sugar and acid, providing comprehensive quality coverage. Through the rotation platform of the positioning adjustment mechanism and the cooperation of a stepper motor, the apple is driven to achieve four-level precise positioning, avoiding the part difference deviation caused by traditional devices that only detect a single surface. It reflects the overall sugar and acid distribution of the apple, solves the detection limitations of single components and single parts, and realizes the simultaneous detection of apple sugar and acidity and overall quality evaluation.

[0018] 3. By relying on the industrial control computer system and multiple sensors in collaboration, an unmanned process of sample loading, positioning, detection and result output is constructed. The front of the instrument shell is embedded with a human-machine interface, which supports parameter setting and result display. No professional personnel are required to disassemble the equipment. Ordinary operators can get started after simple training. It solves the limitations of detection of single components and single parts, and realizes simultaneous detection of apple sugar content and acidity and overall quality evaluation.

[0019] 4. By installing a shock absorber at the bottom of the instrument housing, the interference of equipment vibration on spectral acquisition is reduced. A combination of broadband halogen lamps and spectral alignment boxes is used to ensure the stability of the spectral signal by reducing light intensity attenuation. The tilt of the lifting platform is limited by the limiting vertical rod and the connecting lifting frame. The displacement sensor calibrates the lifting height in real time, and the angle sensor corrects the rotation angle to avoid spectral acquisition deviation caused by apple offset. This further improves the signal accuracy and solves the problems of unstable light intensity, positioning deviation and wavelength mismatch, achieving high-precision and high-stability detection. Attached Figure Description

[0020] Figure 1 This is a front perspective view of the present invention; Figure 2 This is a rear perspective view of the present invention; Figure 3 This is a left-side perspective view of the present invention; Figure 4 This is a top perspective view of the internal structure of this utility model; Figure 5 This is a schematic diagram illustrating the structure of the lifting platform and the rotating platform of this utility model; Figure 6 This is a schematic diagram illustrating the structure of the through-slot, photoelectric sensor, broadband halogen lamp, broadband fiber optic cable, light source, CCD camera, fiber optic probe, lifting platform, connecting seat, lead screw sleeve, lead screw, lifting motor, limiting vertical rod, vertical rod L-shaped bracket, lifting slot and connecting lifting frame of this utility model. Figure 7 This is a schematic diagram of the overall structure of this utility model; Figure 8 This is a schematic diagram of the spectral acquisition system of this utility model; Figure 9 This is a schematic diagram of the sample introduction structure, rotation positioning structure, and lifting adjustment mechanism of this utility model.

[0021] In the diagram: 1. Instrument housing; 2. Human-machine interface; 3. Shock absorber; 4. Conveyor belt; 5. Drive motor; 6. Conveyor roller; 7. Mounting plate; 8. Industrial computer; 9. Control module; 10. Data acquisition card; 11. Lifting platform; 12. Connecting seat; 13. Lead screw sleeve; 14. Lead screw; 15. Lifting motor; 16. Limiting vertical rod; 17. Vertical rod L-shaped bracket; 18. Lifting groove; 19. Connecting lifting frame; 20. Fastening bolt; 21. Rotating platform; 22. Rotating connecting rod; 23. Stepper motor; 24. Displacement sensor; 25. Displacement sensor bracket; 26. Through groove; 27. Photoelectric sensor; 28. Broadband halogen lamp; 29. ​​Broadband fiber optic cable; 30. Spectrum alignment box; 31. Near-infrared spectrometer main unit; 32. Light source; 33. CCD camera; 34. Fiber optic probe; 35. Angle sensor. Detailed Implementation

[0022] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0023] Please see Figure 1-9This utility model provides a near-infrared detection device for apple sugar content and acidity, including an instrument housing 1, shock absorbers 3 fixedly installed at the four corners of the bottom of the instrument housing 1, and an integrated sample delivery mechanism, a positioning adjustment mechanism, a spectral acquisition system and an industrial control computer control system inside the instrument housing 1. The sample delivery mechanism includes a conveyor belt 4 arranged horizontally along the length of the instrument housing 1. Conveyor rollers 6 are rotatably supported on both sides of the conveyor belt 4. A drive motor 5 is fixedly installed on one side of the conveyor belt 4. The output shaft of the drive motor 5 is connected to the rotating shaft of the conveyor roller 6 through a coupling. The positioning adjustment mechanism is set at the other end of the conveyor belt 4, including a lifting platform 11 and a rotating platform 21 horizontally located on the top surface of the lifting platform 11. A connecting seat 12 is fixed at the bottom center of the lifting platform 11. The connecting seat 12 is fixedly connected to the lead screw sleeve 13. The lead screw sleeve 13 is threaded with a lead screw 14. The bottom of the lead screw 14 is connected to the output shaft of the lifting motor 15. Limiting vertical rods 16 are set on the outer sides of the four corners of the lifting platform 11. The limiting vertical rods 16 are vertically fixed to the rear side of the instrument housing 1 through the vertical rod L-shaped bracket 17. The spectral acquisition system is positioned directly above the rotating platform 21 and includes a light source 32, a broadband halogen lamp 28, a spectral alignment box 30, a near-infrared spectrometer main unit 31, a CCD camera 33, and a fiber optic probe 34. The broadband halogen lamp 28 is connected to the spectral alignment box 30 via a broadband fiber optic cable 29, and the fiber optic probe 34 is connected to the near-infrared spectrometer main unit 31 via armored fiber optic cable. The light source 32, the broadband halogen lamp 28, the CCD camera 33, and the fiber optic probe 34 are all horizontally fixed inside the instrument housing 1 above the instrument housing 1 by a bracket, and the central axes of the four are located on the same horizontal plane. The CCD camera 33 is located between the broadband halogen lamp 28 and the fiber optic probe 34, and the light source 32 is arranged adjacent to the broadband halogen lamp 28. The industrial computer control system includes an industrial computer 8, a control module 9, and a data acquisition card 10. A mounting plate 7 is vertically fixed inside the rear side of the instrument housing 1. The industrial computer 8, the control module 9, and the data acquisition card 10 are all fixed on the mounting plate 7. The industrial computer 8 is electrically connected to the control module 9 and the data acquisition card 10 respectively. The control module 9 is electrically connected to the drive motor 5 and the lifting motor 15 respectively. Specifically: By using the instrument housing 1 as a carrier, the shock absorbers 3 fixed at the four corners of the bottom can reduce the mechanical vibration during the operation of the equipment, avoid vibration interference with the stability of the spectral acquisition signal, and solve the problem of detection accuracy deviation caused by vibration in traditional devices; The instrument housing 1 integrates four core modules: sample delivery mechanism, positioning adjustment mechanism, spectral acquisition system and industrial control computer control system, to realize full automation of the "sample loading-positioning-detection-data processing" process, replace manual operation and improve detection efficiency.

[0024] Sample delivery mechanism: The conveyor belt 4, which is horizontally arranged along the length of the instrument housing 1, serves as the apple delivery channel. The conveyor rollers 6 on both sides provide rotational support for the conveyor belt 4. The drive motor 5 is connected to the shaft of the conveyor rollers 6 through a coupling to achieve automatic sample loading, which solves the problem of low efficiency of manual sample loading in traditional devices and lays the foundation for industrial batch testing.

[0025] Positioning and Adjustment Mechanism: Located at the end of conveyor belt 4, its core function is to precisely adjust the apple to the "equatorial detection height" and achieve multi-angle positioning, solving the problem that traditional devices can only detect a single part and cannot reflect the overall quality of the fruit. Specifically: Lifting Adjustment: The lifting motor 15 drives the lead screw 14 to rotate. The threaded engagement between the lead screw 14 and the lead screw sleeve 13 converts the rotational motion into linear motion, driving the connecting seat 12 and the top lifting platform 11 to rise and fall vertically. The limiting vertical rods 16 on the four outer corners of the lifting platform 11 are fixed to the rear of the instrument housing 1 via vertical rod L-shaped brackets 17, guiding the lifting trajectory of the lifting platform 11 and preventing tilting. Rotation Adjustment: The rotation platform 21 is horizontally placed on the top surface of the lifting platform 11. It is subsequently driven by a stepper motor to achieve multi-angle rotation, ensuring that the spectrum of different parts of the apple can be collected.

[0026] Spectral acquisition system: Located directly above the rotating platform 21, this is the core component for simultaneous detection of sugar and acidity, solving the problem of traditional devices only being able to detect a single component and having mismatched wavelength ranges for apple characteristic peaks. Specifically: Light source coordination: Light source 32 and broadband halogen lamp 28 are positioned adjacent to each other, emitting light collaboratively. The effective spectral range covers both sugar characteristic peaks and the 2200-2500nm characteristic peak of malic acid OH bonding frequency vibration, providing a spectral basis for simultaneous sugar and acid detection. The broadband halogen lamp 28 is connected to the spectral alignment box 30 via broadband fiber optic cable 29, ensuring stable light intensity output and avoiding the rapid light decay problem of traditional tungsten filament lamps.

[0027] Signal acquisition: The fiber optic probe 34 is connected to the near-infrared spectrometer host 31 via armored fiber optic cable, and can acquire the near-infrared diffuse reflectance spectrum signal of the apple surface; the CCD camera 33 is located between the broadband halogen lamp 28 and the fiber optic probe 34, and its central axis is coplanar with other components, and can acquire the equatorial image of the apple to determine whether the apple is accurately aligned, avoiding acquisition errors caused by position deviation.

[0028] Industrial computer control system: The industrial computer 8, control module 9 and data acquisition card 10 are fixed on the mounting plate 7 on the rear side of the instrument housing 1, forming a closed-loop system of "central control - signal acquisition - execution drive": The industrial computer 8 serves as the core, running the detection and control program and data processing algorithm; the control module 9 receives instructions from the industrial computer and drives the drive motor 5, lifting motor 15 and other actuators to perform actions; the data acquisition card 10 synchronously receives signals from various sensors to ensure that all modules work together.

[0029] A through groove 26 along the width direction of the conveyor belt is provided at one end of the conveyor belt 4 near the positioning adjustment mechanism. A photoelectric sensor 27 is fixedly installed on the side of the through groove 26 away from the positioning adjustment mechanism by an L-shaped bracket. The detection end of the photoelectric sensor 27 is horizontally facing the conveying surface of the conveyor belt 4. The photoelectric sensor 27 is electrically connected to the data acquisition card 10. The output shaft of the drive motor 5 and the rotating shaft of the conveyor roller 6 are coaxially driven through an elastic coupling to ensure transmission stability. Specifically: A through slot 26 along the width direction is opened at the end of the conveyor belt 4 near the positioning and adjustment mechanism. A photoelectric sensor 27 is fixed next to the through slot 26 by an L-shaped bracket, with the detection end horizontally facing the conveyor surface of the conveyor belt 4. Its working principle is as follows: When the apple moves with the conveyor belt 4 above the through slot 26, the apple blocks the detection beam of the photoelectric sensor 27. The sensor immediately transmits a "apple in place" signal to the data acquisition card 10. After receiving the signal, the industrial control computer 8 controls the drive motor 5 to stop operating through the control module 9, so that the apple accurately stops at the end of the conveyor belt 4, waiting for the subsequent lifting platform 11 to receive it. At the same time, the drive motor 5 and the conveyor roller 6 shaft are connected by a flexible coupling, which can buffer the mechanical impact during transmission, avoid apple deviation due to conveyor belt 4 jamming, further improve conveying stability, and meet the needs of large-scale production lines.

[0030] A displacement sensor 24 is vertically fixed on the side of the lifting platform 11 away from the rotating platform 21 by a displacement sensor bracket 25. The detection end of the displacement sensor 24 is horizontally facing the side of the lifting platform 11. The displacement sensor 24 is electrically connected to the data acquisition card 10. A connecting lifting frame 19 is detachably installed on the outer wall of the lifting platform 11 by fastening bolts 20. A vertical lifting groove 18 is opened on the inner wall of the limiting vertical rod 16. The end of the connecting lifting frame 19 away from the lifting platform 11 is slidably embedded in the lifting groove 18. Specifically: To ensure that the lifting platform 11 accurately adjusts the apple to the "equatorial detection height," a displacement sensor 24 is fixed on the side of the lifting platform 11 away from the rotating platform 21 via a displacement sensor bracket 25. Its detection end faces the side of the lifting platform 11, allowing it to collect height data of the lifting platform 11 in real time, which is then fed back to the industrial control computer 8 via a data acquisition card 10. When the height reaches the preset value, the industrial control computer 8 controls the lifting motor 15 to stop via the control module 9, solving the problem of low accuracy in manual height adjustment using traditional devices. Furthermore, a connecting lifting frame 19 is installed on the outer wall of the lifting platform 11 via fastening bolts 20. Its end slides into the lifting groove 18 inside the limiting vertical rod 16, forming a "guide-limit" dual guarantee: limiting the horizontal deviation of the lifting platform 11 and preventing tilting during lifting, further improving positioning stability.

[0031] A rotating connecting rod 22 is vertically fixed at the bottom center of the rotating platform 21. The rotating connecting rod 22 passes through the central through hole of the lifting platform 11 and is connected to the output shaft of the stepper motor 23 via a synchronous belt. The stepper motor 23 is fixed in the cavity inside the lifting platform 11 by a motor bracket. An angle sensor 35 is fixed on the lifting platform 11 on the side of the rotating platform 21 by a triangular bracket. The detection end of the angle sensor 35 faces the edge groove of the rotating platform 21. The angle sensor 35 is electrically connected to the data acquisition card 10, and the control module 9 is electrically connected to the stepper motor 23. Specifically, the drive and angle control of the rotating platform 21 adopt the following design: the rotating connecting rod 22 at the bottom of the rotating platform 21 passes through the central through hole of the lifting platform 11 and is connected to the output shaft of the stepper motor 23 in the internal cavity of the lifting platform 11 via a synchronous belt; the stepper motor 23 is a high-precision servo motor, which can drive the rotating platform 21 to achieve precise positioning at four levels: 0°, 90°, 180°, and 270°. At the same time, the angle sensor 35 on the side of the rotating platform 21 is fixed to the lifting platform 11 by a triangular bracket, with the detection end facing the edge groove of the rotating platform 21, which can collect rotation angle data in real time and feed it back to the data acquisition card 10; the industrial control computer 8 will control the stepper motor 23 to make fine adjustments to ensure that the spectral acquisition at each angle is accurate and avoid detection errors caused by angle deviation.

[0032] The light source 32 and the broadband halogen lamp 28 work together as a detection light source. There is a horizontal angle between the fiber optic probe 34 and the broadband halogen lamp 28. There is a horizontal angle between the CCD camera 33 and the broadband halogen lamp 28. The CCD camera 33 is electrically connected to the control module 9. Specifically: the horizontal angle between the fiber optic probe 34 and the broadband halogen lamp 28 is set to 120°, which maximizes the reception of diffuse reflectance spectral signals from the apple surface; the horizontal angle between the CCD camera 33 and the broadband halogen lamp 28 is set to 60°, and the CCD camera 33 is electrically connected to the control module 9. When the apple equatorial image acquired by the CCD camera 33 displays "Apple not aligned," the control module 9 will trigger the lifting motor 15 or the stepper motor 23 to fine-tune until the position is accurate, avoiding acquisition deviation from the source. At the same time, the coordinated light emission design of the light source 32 and the broadband halogen lamp 28 can improve the uniformity of illumination on the apple surface, avoiding the problems of weak spectral signals and low signal-to-noise ratio caused by insufficient local illumination, ensuring that the signal received by the near-infrared spectrometer host 31 is stable and reliable.

[0033] A human-machine interface 2 is embedded in the front surface of the instrument housing 1. The human-machine interface 2 is electrically connected to the industrial control computer 8. The data acquisition card 10 is electrically connected to the displacement sensor 24, the angle sensor 35, and the photoelectric sensor 27 respectively. The control module 9 is also electrically connected to the broadband halogen lamp 28, the light source 32, and the CCD camera 33 respectively. Specifically: To improve the ease of operation and control accuracy of the device, the human-machine interface 2 embedded in the front surface of the instrument shell 1 is electrically connected to the industrial control computer 8. The data acquisition card 10 is electrically connected to the displacement sensor 24, the angle sensor 35, and the photoelectric sensor 27, which can simultaneously acquire signals from the three types of sensors to ensure that the industrial control computer 8 can monitor the equipment status in real time. In addition to driving the motor, the control module 9 is also electrically connected to the broadband halogen lamp 28, the light source 32, and the CCD camera 33, which can realize the timing coordination of "light source start / stop - image acquisition - spectrum acquisition".

[0034] There are four limit rods 16, which correspond to the four outer corners of the lifting platform 11 respectively, and the axes of the four limit rods 16 are distributed in a rectangle. The length of the lifting groove 18 is adapted to the maximum lifting stroke of the lifting platform 11. Specifically, there are four limiting vertical rods 16, which correspond to the four outer corners of the lifting platform 11 respectively. The axes of the four limiting vertical rods 16 are distributed in a rectangle to form a "four-point positioning" guide structure. Compared with the two-rod guide method, the length of the lifting groove 18 is adapted to the maximum lifting stroke of the lifting platform 11, ensuring that the lifting platform 11 can cover the equatorial positioning requirements of apples of different sizes and improve the compatibility of the device with apple sizes.

[0035] In this invention, the instrument housing 1 serves as a carrier, and the shock absorbers 3 fixed at the four corners of the bottom can reduce the mechanical vibration during equipment operation, avoid vibration interference with the stability of the spectral acquisition signal, and solve the problem of detection accuracy deviation caused by vibration in traditional devices. The instrument housing 1 integrates four core modules: a sample delivery mechanism, a positioning adjustment mechanism, a spectral acquisition system, and an industrial control computer control system, realizing full automation of the "sample loading-positioning-detection-data processing" process, replacing manual operation and improving detection efficiency.

[0036] Sample delivery mechanism: The conveyor belt 4, which is horizontally arranged along the length of the instrument housing 1, serves as the apple delivery channel. The conveyor rollers 6 on both sides provide rotational support for the conveyor belt 4. The drive motor 5 is connected to the shaft of the conveyor rollers 6 through a coupling to achieve automatic sample loading, which solves the problem of low efficiency of manual sample loading in traditional devices and lays the foundation for industrial batch testing.

[0037] Positioning and Adjustment Mechanism: Located at the end of conveyor belt 4, its core function is to precisely adjust the apple to the "equatorial detection height" and achieve multi-angle positioning, solving the problem that traditional devices can only detect a single part and cannot reflect the overall quality of the fruit. Specifically: Lifting Adjustment: The lifting motor 15 drives the lead screw 14 to rotate. The threaded engagement between the lead screw 14 and the lead screw sleeve 13 converts the rotational motion into linear motion, driving the connecting seat 12 and the top lifting platform 11 to rise and fall vertically. The limiting vertical rods 16 on the four outer corners of the lifting platform 11 are fixed to the rear of the instrument housing 1 via vertical rod L-shaped brackets 17, guiding the lifting trajectory of the lifting platform 11 and preventing tilting. Rotation Adjustment: The rotation platform 21 is horizontally placed on the top surface of the lifting platform 11. It is subsequently driven by a stepper motor to achieve multi-angle rotation, ensuring that the spectrum of different parts of the apple can be collected.

[0038] Spectral acquisition system: Located directly above the rotating platform 21, this is the core component for simultaneous detection of sugar and acidity, solving the problem of traditional devices only being able to detect a single component and having mismatched wavelength ranges for apple characteristic peaks. Specifically: Light source coordination: Light source 32 and broadband halogen lamp 28 are positioned adjacent to each other, emitting light collaboratively. The effective spectral range covers both sugar characteristic peaks and the 2200-2500nm characteristic peak of malic acid OH bonding frequency vibration, providing a spectral basis for simultaneous sugar and acid detection. The broadband halogen lamp 28 is connected to the spectral alignment box 30 via broadband fiber optic cable 29, ensuring stable light intensity output and avoiding the rapid light decay problem of traditional tungsten filament lamps.

[0039] Signal acquisition: The fiber optic probe 34 is connected to the near-infrared spectrometer host 31 via armored fiber optic cable, and can acquire the near-infrared diffuse reflectance spectrum signal of the apple surface; the CCD camera 33 is located between the broadband halogen lamp 28 and the fiber optic probe 34, and its central axis is coplanar with other components, and can acquire the equatorial image of the apple to determine whether the apple is accurately aligned, avoiding acquisition errors caused by position deviation.

[0040] Industrial computer control system: The industrial computer 8, control module 9 and data acquisition card 10 are fixed on the mounting plate 7 on the rear side of the instrument housing 1, forming a closed-loop system of "central control - signal acquisition - execution drive": The industrial computer 8 serves as the core, running the detection and control program and data processing algorithm; the control module 9 receives instructions from the industrial computer and drives the drive motor 5, lifting motor 15 and other actuators to perform actions; the data acquisition card 10 synchronously receives signals from various sensors to ensure that all modules work together.

[0041] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A near-infrared detection device for apple sugar content and acidity, comprising an instrument housing (1), characterized in that: The instrument housing (1) has shock absorbers (3) fixedly installed at the four corners of the bottom. The instrument housing (1) integrates a sample delivery mechanism, a positioning adjustment mechanism, a spectral acquisition system and an industrial control computer control system. The sample delivery mechanism includes a conveyor belt (4) arranged horizontally along the length of the instrument housing (1). Conveyor rollers (6) are rotatably supported on both sides of the conveyor belt (4). A drive motor (5) is fixedly installed on one side of the conveyor belt (4). The output shaft of the drive motor (5) is connected to the rotating shaft of the conveyor roller (6) through a coupling. The positioning adjustment mechanism is set at the other end of the conveyor belt (4), including a lifting platform (11) and a rotating platform (21) horizontally located on the top surface of the lifting platform (11). A connecting seat (12) is fixed at the bottom center of the lifting platform (11). The connecting seat (12) is fixedly connected to the lead screw sleeve (13). The lead screw sleeve (13) is threaded with a lead screw (14). The bottom of the lead screw (14) is connected to the output shaft of the lifting motor (15). Limiting vertical rods (16) are set on the four outer corners of the lifting platform (11). The limiting vertical rods (16) are vertically fixed to the rear side of the instrument shell (1) through the vertical rod L-shaped bracket (17). The spectral acquisition system is positioned directly above the rotating platform (21) and includes a light source (32), a broadband halogen lamp (28), a spectral alignment box (30), a near-infrared spectrometer main unit (31), a CCD camera (33), and an optical fiber probe (34). The broadband halogen lamp (28) is connected to the spectral alignment box (30) via a broadband fiber (29), and the optical fiber probe (34) is connected to the near-infrared spectrometer main unit (31) via armored optical fiber. The light source (32), broadband halogen lamp (28), CCD camera (33), and optical fiber probe (34) are all horizontally fixed above the inside of the instrument housing (1) by a bracket, and the central axes of the four are located on the same horizontal plane. The CCD camera (33) is located between the broadband halogen lamp (28) and the optical fiber probe (34), and the light source (32) is arranged adjacent to the broadband halogen lamp (28). The industrial control system includes an industrial computer (8), a control module (9) and a data acquisition card (10). A mounting plate (7) is vertically fixed inside the rear side of the instrument housing (1). The industrial computer (8), the control module (9) and the data acquisition card (10) are all fixed on the mounting plate (7). The industrial computer (8) is electrically connected to the control module (9) and the data acquisition card (10) respectively. The control module (9) is electrically connected to the drive motor (5) and the lifting motor (15) respectively.

2. The near-infrared detection device for apple sugar content and acidity according to claim 1, characterized in that: The conveyor belt (4) has a through groove (26) along the width direction of the conveyor belt at one end near the positioning adjustment mechanism. A photoelectric sensor (27) is fixedly installed on the side of the through groove (26) away from the positioning adjustment mechanism by an L-shaped bracket. The detection end of the photoelectric sensor (27) is horizontally facing the conveying surface of the conveyor belt (4). The photoelectric sensor (27) is electrically connected to the data acquisition card (10). The output shaft of the drive motor (5) and the rotating shaft of the conveyor roller (6) are coaxially driven by an elastic coupling to ensure transmission stability.

3. The near-infrared detection device for apple sugar content and acidity according to claim 1, characterized in that: A displacement sensor (24) is vertically fixed on the side of the lifting platform (11) away from the rotating platform (21) by a displacement sensor bracket (25). The detection end of the displacement sensor (24) is horizontally facing the side of the lifting platform (11). The displacement sensor (24) is electrically connected to the data acquisition card (10). A connecting lifting frame (19) is detachably installed on the outer wall of the lifting platform (11) by fastening bolts (20). A lifting groove (18) is opened on the inner wall of the limiting vertical rod (16) along the vertical direction. The end of the connecting lifting frame (19) away from the lifting platform (11) is slidably embedded in the lifting groove (18).

4. The near-infrared detection device for apple sugar content and acidity according to claim 1, characterized in that: A rotating connecting rod (22) is vertically fixed at the bottom center of the rotating platform (21). The rotating connecting rod (22) passes through the central through hole of the lifting platform (11) and is connected to the output shaft of the stepper motor (23) via a synchronous belt. The stepper motor (23) is fixed in the cavity inside the lifting platform (11) by a motor bracket. An angle sensor (35) is fixed on the lifting platform (11) on the side of the rotating platform (21) by a triangular bracket. The detection end of the angle sensor (35) faces the edge tooth groove of the rotating platform (21). The angle sensor (35) is electrically connected to the data acquisition card (10). The control module (9) is electrically connected to the stepper motor (23).

5. The near-infrared detection device for apple sugar content and acidity according to claim 1, characterized in that: The light source (32) and the broadband halogen lamp (28) work together as a detection light source. There is a horizontal angle between the fiber optic probe (34) and the broadband halogen lamp (28). There is a horizontal angle between the CCD camera (33) and the broadband halogen lamp (28). The CCD camera (33) is electrically connected to the control module (9).

6. The near-infrared detection device for apple sugar content and acidity according to claim 1, characterized in that: The front surface of the instrument housing (1) is embedded with a human-machine interface (2), which is electrically connected to the industrial control computer (8). The data acquisition card (10) is electrically connected to the displacement sensor (24), the angle sensor (35), and the photoelectric sensor (27). The control module (9) is also electrically connected to the broadband halogen lamp (28), the light source (32), and the CCD camera (33).

7. The near-infrared detection device for apple sugar content and acidity according to claim 3, characterized in that: There are four limiting vertical rods (16), which correspond to the four outer corners of the lifting platform (11) respectively, and the axes of the four limiting vertical rods (16) are distributed in a rectangular shape. The length of the lifting groove (18) is adapted to the maximum lifting stroke of the lifting platform (11).

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