Apple sugar degree nondestructive measurement device

Abstract

The utility model relates to an apple sugar degree nondestructive measurement device. The device comprises a control module, an infrared emission control module and an infrared light signal acquisition module, wherein the infrared emission control module comprises a reference voltage source, a first signal amplifier and a plurality of infrared light emitting diodes; the control module is connected with the reference voltage source, the output end of the reference voltage source is connected with the input end of the first signal amplifier, and the first signal amplifier is connected with the infrared light emitting diode; the infrared light signal acquisition module comprises an optical signal acquisition device, a second signal amplifier and an analog-to-digital converter, the optical signal acquisition device is connected with the second signal amplifier, the second signal amplifier is connected with the analog-to-digital converter, and the analog-to-digital converter is connected with the control module. The device can realize rapid and nondestructive measurement of the apple sugar degree, and is high in detection efficiency.

Description

Technical Field

[0001] The utility model relates to the technical field of non-destructive measurement of the sugar content of apples, in particular to a non-destructive measurement device for the sugar content of apples. Background Art

[0002] Apples are a fruit with high nutritional value and good shelf life, and their sugar content is an important criterion for people to choose apples. However, traditional sugar content measurement methods are mostly destructive, meaning they damage the apples during the testing process, which not only affects the integrity of the fruit but also limits its subsequent use, making it quite inconvenient to use. Currently, on the market, equipment that can accurately and non-destructively measure the sugar content of apples has excellent performance, but its high price has become a major obstacle to its widespread application. In view of this situation, the development of low-cost, high-precision non-destructive sugar content measurement instruments is particularly important. It is not only an urgent need to achieve the localization of technology, but also a key measure to promote agricultural scientific and technological progress and improve economic benefits.

[0003] Existing non-destructive testing methods for apple sugar content are becoming more diverse, but each faces different challenges:

[0004] Spectrometer technology estimates sugar content by collecting spectral information and applying the KS algorithm. While this method has some scientific merit, the complex equipment structure and high cost limit its widespread application. Phase-locked loop optical measurement, while effectively improving measurement accuracy, comes with a significant increase in instrument size, hindering portability and rapid on-site testing. Methods that employ complex multi-band data models can theoretically capture more detailed information, but in practice, their measurement accuracy has fallen short of expectations, likely due to a gap between the model's complexity and its adaptability to the actual application environment. Furthermore, neural network algorithms based on image analysis have also been applied to predict the sugar content of apples, indirectly assessing their sugar content by processing apple images. However, this method is significantly influenced by natural factors such as the apple's origin and climate. The resulting diversity of skin characteristics increases the difficulty of analysis, which in turn affects the accuracy of sugar content prediction. Utility Model Content

[0005] To address the above technical issues, the present invention provides a non-destructive device for measuring the sugar content of apples. Based on infrared spectroscopy technology, this device controls a high-precision voltage reference source to enable and disable the infrared emission control module. When the infrared emission control module is disabled, ambient light signals can be measured, eliminating the influence of ambient light and improving measurement accuracy. This device, combined with a single-power supply and a programmable differential amplifier circuit for receiving the spectrum, improves measurement accuracy while reducing circuit complexity. The present invention provides a non-destructive device for measuring the sugar content of apples, specifically including the following modules:

[0006] Control module;

[0007] An infrared emission control module, comprising a reference voltage source, a first signal amplifier, and a plurality of infrared light-emitting diodes; wherein the control module is connected to the reference voltage source, an output end of the reference voltage source is connected to an input end of the first signal amplifier, and the first signal amplifier is connected to the infrared light-emitting diodes;

[0008] And an infrared light signal acquisition module, which includes an optical signal collector, a second signal amplifier and an analog-to-digital converter. The optical signal collector is connected to the second signal amplifier, the second signal amplifier is connected to the analog-to-digital converter, and the analog-to-digital converter is connected to the control module.

[0009] In one embodiment of the present invention, the first signal amplifier includes a first operational amplifier, a second operational amplifier, a third operational amplifier and a fourth operational amplifier, the output end of the reference voltage source is connected to the non-inverting input end of the first operational amplifier, and the inverting input end of the first operational amplifier is connected to its output end.

[0010] In one embodiment of the present utility model, a first node and a second node are provided on a branch leading from the output end of the first operational amplifier, and the infrared emission control module further includes a first resistor, a second resistor, a third resistor and a fourth resistor, the first resistor is arranged between the first node and the second node, and the resistance values ​​of the second resistor, the third resistor and the fourth resistor are equal.

[0011] In one embodiment of the present invention, the inverting input terminal of the second operational amplifier is connected to the first node through the second resistor, and the non-inverting input terminal thereof is connected to the second node; the inverting input terminal of the third operational amplifier is connected to the first node through the third resistor, and the non-inverting input terminal thereof is connected to the second node; the inverting input terminal of the fourth operational amplifier is connected to the first node through the fourth resistor, and the non-inverting input terminal thereof is connected to the second node.

[0012] In one embodiment of the present invention, the infrared light emitting diode includes a first infrared light emitting diode, a second infrared light emitting diode and a third infrared light emitting diode; the positive electrode of the first infrared light emitting diode is connected to the inverting input terminal of the second operational amplifier, and the negative electrode is connected to the output terminal of the second operational amplifier.

[0013] In one embodiment of the present invention, the positive electrode of the second infrared light-emitting diode is connected to the inverting input terminal of the third operational amplifier, and the negative electrode is connected to the output terminal of the third operational amplifier; the positive electrode of the third infrared light-emitting diode is connected to the inverting input terminal of the fourth operational amplifier, and the negative electrode is connected to the output terminal of the fourth operational amplifier.

[0014] In one embodiment of the present invention, the optical signal collector is a photodiode, and the positive electrode of the optical signal collector is connected to the inverting input terminal of the second signal amplifier, and the negative electrode is connected to the non-inverting input terminal of the second signal amplifier, and the non-inverting input terminal is grounded.

[0015] In one embodiment of the present invention, the infrared light signal acquisition module further includes a filtering unit, and the inverting input end of the second signal amplifier is connected to the output end thereof through the filtering unit.

[0016] In one embodiment of the present invention, the input end of the analog-to-digital converter is connected to the output end of the second signal amplifier, and the analog-to-digital converter is connected to the data receiving port of the control module via a serial clock pin and a serial data pin.

[0017] The above technical solution of the utility model has the following advantages compared with the prior art:

[0018] The utility model realizes the rapid and non-destructive measurement of the sugar content of apples. Through precise infrared light constant current control and efficient optical signal processing, the measurement accuracy and stability are improved. The automated process simplifies the operation and improves the detection efficiency. It has strong adaptability and can be widely used in apple quality evaluation and grading, providing reliable technical support for agricultural production and market circulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the content of the utility model easier to understand, the utility model is further described in detail below based on the specific embodiments of the utility model and in conjunction with the accompanying drawings, wherein

[0020] Figure 1 This is a schematic structural diagram of the non-destructive measuring device for the sugar content of apples provided in Example 1 of the present invention;

[0021] Figure 2 This is a circuit diagram of the control module provided in Example 1 of the present utility model;

[0022] Figure 3 This is a circuit diagram of the infrared emission control module provided in Example 1 of the present utility model;

[0023] Figure 4 This is a circuit diagram of the infrared light signal acquisition module provided in Example 1 of the present utility model;

[0024] Description of the accompanying drawings in the specification: 10, control module; 20, infrared emission control module; 30, infrared light signal acquisition module. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0026] Reference Figures 1 to 4 As shown, the present invention provides a non-destructive measurement device for the sugar content of apples, which specifically includes the following modules:

[0027] Control module 10, infrared emission control module 20 and infrared light signal acquisition module 30;

[0028] The infrared emission control module 20 includes a reference voltage source U2, a first signal amplifier, and a plurality of infrared light-emitting diodes; the control module 10 is connected to the reference voltage source U2, the output end of the reference voltage source U2 is connected to the input end of the first signal amplifier, and the first signal amplifier is connected to the infrared light-emitting diodes;

[0029] The infrared light signal acquisition module 30 includes an optical signal collector D5, a second signal amplifier U5 and an analog-to-digital converter U6. The optical signal collector D5 is connected to the second signal amplifier U5, the second signal amplifier U5 is connected to the analog-to-digital converter U6, and the analog-to-digital converter U6 is connected to the control module 10.

[0030] Specific as Figure 3 As shown, the first signal amplifier includes a first operational amplifier U3A, a second operational amplifier U3B, a third operational amplifier U4A and a fourth operational amplifier U4B, the output terminal VOUT of the reference voltage source U2 is connected to the non-inverting input terminal of the first operational amplifier U3A, and the inverting input terminal of the first operational amplifier U3A is connected to its output terminal.

[0031] Furthermore, a branch extending from the output of the first operational amplifier U3A is provided with a first node LEDPOW and a second node LEDCON. The infrared emission control module further includes a first resistor R6, a second resistor R8, a third resistor R9, and a fourth resistor R10. The first resistor R6 is provided between the first node LEDPOW and the second node LEDCON to form a voltage drop. The second resistor R8, the third resistor R9, and the fourth resistor R10 have equal resistance values.

[0032] The inverting input terminal of the second operational amplifier U3B is connected to the first node LEDPOW through the second resistor R8, and the non-inverting input terminal thereof is connected to the second node LEDCON.

[0033] The inverting input terminal of the third operational amplifier U4A is connected to the first node LEDPOW through the third resistor R9, and the non-inverting input terminal thereof is connected to the second node LEDCON.

[0034] The inverting input terminal of the fourth operational amplifier U4B is connected to the first node LEDPOW through the fourth resistor R10, and the non-inverting input terminal thereof is connected to the second node LEDCON.

[0035] In addition, the infrared light-emitting diode includes a first infrared light-emitting diode D1, a second infrared light-emitting diode D2 and a third infrared light-emitting diode D3; the positive electrode of the first infrared light-emitting diode D1 is connected to the inverting input terminal of the second operational amplifier U3B, and the negative electrode is connected to the output terminal of the second operational amplifier U3B.

[0036] The positive electrode of the second infrared light-emitting diode D2 is connected to the inverting input terminal of the third operational amplifier U4A, and the negative electrode is connected to the output terminal of the third operational amplifier U4A; the positive electrode of the third infrared light-emitting diode D3 is connected to the inverting input terminal of the fourth operational amplifier U4B, and the negative electrode is connected to the output terminal of the fourth operational amplifier U4B.

[0037] like Figure 4 As shown, the optical signal collector D5 is a photodiode S2387, and the second signal amplifier U5 is a precision op amp SGM8551. The positive terminal of the optical signal collector D5 is connected to the inverting input of the second signal amplifier U5, and the negative terminal is connected to the non-inverting input of the second signal amplifier U5, which is grounded. The optical signal collector D5 and the second signal amplifier U5 form a single-supply spectrum receiving circuit based on the precision op amp SGM8551.

[0038] When light strikes the photodiode D5, a current proportional to the light intensity flows. This current enters the inverting input of the second signal amplifier U5. Since the non-inverting input is grounded (forming a virtual ground), the second signal amplifier U5 adjusts its output voltage so that the voltage at the inverting input (i.e., the voltage at the anode of the photodiode) is as close to ground as possible, thereby maintaining the voltage difference at the input of the second signal amplifier U5 at zero (i.e., a virtual short).

[0039] In this embodiment, the infrared light signal acquisition module 30 further includes a filtering unit, and the inverting input terminal of the second signal amplifier U5 is connected to its output terminal through the filtering unit. Figure 4 It can be seen that the filtering unit is an RC filtering circuit composed of a resistor R11 and a capacitor C3 connected in parallel to eliminate circuit noise.

[0040] Furthermore, the input end of the analog-to-digital converter U6 is connected to the output end of the second signal amplifier U5, and the analog-to-digital converter U6 is connected to the data receiving port (SCL pin, SDA pin) of the control module 10 through the serial clock pin SCL1 and the serial data pin SDA1.

[0041] Preferably, the control module 10 is a STM32F103C8T6ARM single chip microcomputer, the reference voltage source U2 is a high precision reference voltage source ADR421, and the first operational amplifier U3A, the second operational amplifier U3B, the third operational amplifier U4A and the fourth operational amplifier U4B are all operational amplifiers AD8629.

[0042] The analog-to-digital converter U6 is preferably an 18-bit AD conversion chip MCP3421. The photocurrent of the photodiode D5 flows through the resistor R11, and the obtained voltage is input to the analog-to-digital converter U6 for differential sampling. The programmable amplification factor of the analog-to-digital converter U6 is set to 8 to obtain accurate AD data.

[0043] The GND pin of the second signal amplifier U5 is connected to the Vin- pin of the analog-to-digital converter U6 through a resistor R12. The resistor R12 is a 0 ohm resistor and is placed close to the GND pin of the second signal amplifier U5 during PCB wiring. The analog-to-digital converter U6 and the GND of the second signal amplifier U5 are separately connected to improve the differential sampling accuracy of the analog-to-digital converter U6.

[0044] The working principle of the measuring device provided in this embodiment is described in detail below:

[0045] (1) Collecting ambient light signals

[0046] The PB2 pin of the STM32F103C8T6ARM single-chip microcomputer (control module 10) is set to zero. The input terminal (POW pin) voltage of the high-precision reference voltage source ADR421 (reference voltage source U2) is 0.7V, making the output terminal (VREF pin) voltage 0V. The voltage of the first node LEDPOW pin connected to the output terminal of the first operational amplifier U3A is also 0V. Therefore, infrared light-emitting diodes D1, D2, and D3 are all turned off. At this time, the light signal collected by the light signal collector D5 is the ambient light signal. Removing the interference of the ambient light signal when measuring the sugar content of the apple makes the measurement more accurate.

[0047] The ambient light signal data is amplified and differentially sampled by the second signal amplifier U5 and the analog-to-digital converter U6 to obtain first light data.

[0048] (2) Collect the light signal after the apple absorbs infrared light

[0049] The PB2 pin of the control module 10 is set to a floating input. The voltage of the input terminal (POW pin) of the reference voltage source U2 is 4.7V, which meets the power supply requirement of the reference voltage source U2. Therefore, the voltage of the output terminal (VREF pin) is 2.5V. The voltage of the first node LEDPOW pin connected to the output terminal of the first operational amplifier U3A is also 2.5V. Due to the voltage division of the resistor R6, the voltage of the second node LEDCON pin is 2.0V. The voltage difference of the resistors R8, R9, and R10 is 0.5V. Therefore, the current flowing through the infrared light-emitting diodes D1, D2, and D3 is a constant current. The infrared light-emitting diodes D1, D2, and D3 emit stable infrared rays, providing a stable light signal for subsequent measurements.

[0050] The infrared light emitting diodes D1, D2, and D3 emit stable infrared rays to illuminate the apple to be tested. The apple absorbs part of the light. The optical signal is collected by the optical signal collector D5, and then the optical signal is amplified and differentially sampled by the second signal amplifier U5 and the analog-to-digital converter U6 to obtain the second optical data.

[0051] (3) Estimate the sugar content of the apple to be tested

[0052] The first optical data and the second optical data are transmitted back to the control module 10 through the serial clock pin SCL1 and the serial data pin SDA1 of the analog-to-digital converter U6, and the difference between the first optical data and the second optical data is processed using the least squares algorithm to obtain the estimated sugar content data of the apple to be tested.

[0053] The device further includes a display device, which includes but is not limited to an OLED liquid crystal display screen. The control module 10 can display the calculated sugar content data of the apple to be tested on the display device.

[0054] From the above implementation methods, the utility model overcomes the shortcomings of the existing apple sugar content non-destructive measurement control circuit, and makes improvements in measurement accuracy, portability, convenience, and cost. The STM32F103C8T6 single-chip microcomputer is used to control the opening and closing of the high-precision reference voltage source ADR421, and further control the constant current source of the infrared emission circuit. On the one hand, it can emit stable infrared light to illuminate the apple, improving the measurement accuracy. On the other hand, when the infrared light is turned off, the ambient light can be measured, eliminating the influence of ambient light, and no light shielding is required during the measurement process. The single-power spectrum receiving circuit composed of the precision operational amplifier SGM8551 is designed, and then the precision ADC chip MCP3421 is used for differential sampling and program-controlled amplification to obtain a stable voltage, which simplifies the circuit structure and improves the anti-noise ability. The sugar content is calculated according to the least squares model to achieve non-destructive measurement of the sugar content of apples.

[0055] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A non-destructive measuring device for the sugar content of apples, characterized in that: include: Control module; An infrared emission control module, comprising a reference voltage source, a first signal amplifier, and a plurality of infrared light-emitting diodes; wherein the control module is connected to the reference voltage source, an output end of the reference voltage source is connected to an input end of the first signal amplifier, and the first signal amplifier is connected to the infrared light-emitting diodes; and an infrared light signal acquisition module, the infrared light signal acquisition module comprising an optical signal collector, a second signal amplifier and an analog-to-digital converter, the optical signal collector being connected to the second signal amplifier, the second signal amplifier being connected to the analog-to-digital converter, and the analog-to-digital converter being connected to the control module; The optical signal collector is a photodiode, and the positive electrode of the optical signal collector is connected to the inverting input terminal of the second signal amplifier, and the negative electrode is connected to the non-inverting input terminal of the second signal amplifier, and the non-inverting input terminal is grounded.

2. The non-destructive measuring device for the sugar content of apples according to claim 1, characterized in that: The first signal amplifier includes a first operational amplifier, a second operational amplifier, a third operational amplifier and a fourth operational amplifier. The output end of the reference voltage source is connected to the non-inverting input end of the first operational amplifier, and the inverting input end of the first operational amplifier is connected to its output end.

3. The non-destructive measuring device for the sugar content of apples according to claim 2, characterized in that: A first node and a second node are provided on a branch extending from the output end of the first operational amplifier. The infrared emission control module further includes a first resistor, a second resistor, a third resistor and a fourth resistor. The first resistor is provided between the first node and the second node.

4. The non-destructive measuring device for the sugar content of apples according to claim 3, characterized in that: The inverting input terminal of the second operational amplifier is connected to the first node through the second resistor, and the non-inverting input terminal thereof is connected to the second node; the inverting input terminal of the third operational amplifier is connected to the first node through the third resistor, and the non-inverting input terminal thereof is connected to the second node; the inverting input terminal of the fourth operational amplifier is connected to the first node through the fourth resistor, and the non-inverting input terminal thereof is connected to the second node.

5. The non-destructive measuring device for the sugar content of apples according to claim 3, characterized in that: The infrared light emitting diodes include a first infrared light emitting diode, a second infrared light emitting diode and a third infrared light emitting diode; the positive electrode of the first infrared light emitting diode is connected to the inverting input terminal of the second operational amplifier, and the negative electrode is connected to the output terminal of the second operational amplifier.

6. The non-destructive measuring device for the sugar content of apples according to claim 5, characterized in that: The positive electrode of the second infrared light-emitting diode is connected to the inverting input terminal of the third operational amplifier, and the negative electrode is connected to the output terminal of the third operational amplifier; the positive electrode of the third infrared light-emitting diode is connected to the inverting input terminal of the fourth operational amplifier, and the negative electrode is connected to the output terminal of the fourth operational amplifier.

7. The non-destructive measuring device for the sugar content of apples according to claim 3, characterized in that: The resistance values ​​of the second resistor, the third resistor and the fourth resistor are equal.

8. The non-destructive measuring device for the sugar content of apples according to claim 1, characterized in that: The infrared light signal acquisition module further includes a filtering unit, and the inverting input end of the second signal amplifier is connected to the output end thereof through the filtering unit.

9. The non-destructive measuring device for the sugar content of apples according to claim 8, characterized in that: The input end of the analog-to-digital converter is connected to the output end of the second signal amplifier, and the analog-to-digital converter is connected to the data receiving port of the control module through a serial clock pin and a serial data pin.

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