CN220912970U

CN220912970U - Portable blade nitrogen content check out test set

Info

Publication number: CN220912970U
Application number: CN202322447362.2U
Authority: CN
Inventors: 胡瑾; 王浩宇; 魏子渊; 徐婧华
Original assignee: Northwest A&F University
Current assignee: Northwest A&F University
Priority date: 2023-09-08
Filing date: 2023-09-08
Publication date: 2024-05-07
Anticipated expiration: 2033-09-08

Abstract

The portable blade nitrogen content detection equipment comprises a shell structure formed by an upper shell and a lower shell, wherein a reflected light detection probe and a blade clamp are arranged above the shell structure, the blade clamp is covered on the reflected light detection probe, a display screen square hole and a key round hole are sequentially formed in the surface of the upper shell, the display screen square hole is used for installing a result display module, the key round hole is used for installing a key switch module, supporting plates are arranged at the edges of two sides of the interior of the lower shell, and a PCB limiting hole is formed in each supporting plate; the shell comprises a lithium battery, a PCB, an LED and a photodiode; the LEDs and the photodiodes are sequentially arranged; the lithium battery, the PCB board, the display screen and the keys are arranged in a three-layer stacking way, and the whole lithium battery, the PCB board, the display screen and the keys are arranged below the photodiode; the lithium battery is placed in the cavity of the lower shell and clings to the lower shell, and is positioned at the lower layer; the PCB is connected with the lower shell supporting plate through bolts and is positioned at the middle layer; the display screen and the keys are respectively fixed in the square holes of the upper shell display screen and the round holes of the keys and are positioned on the upper layer. The utility model can realize the detection of the nitrogen content of the blade.

Description

Portable blade nitrogen content check out test set

Technical Field

The utility model relates to the technical field of blade nitrogen content detection, in particular to portable blade nitrogen content detection equipment.

Background

The traditional nitrogen content detection method has an empirical judgment method and a chemical analysis method, and has the defects of lack of scientific basis, long time consumption, complex operation, destructiveness, environmental pollution, poor repeatability and the like. The spectrum detection technology has the advantages of rapidness, no damage and the like, and in recent years, certain progress is made by estimating the nitrogen content of the blade through the spectrum technology. However, the conventional spectrum detection system is mostly composed of a halogen light source, a photoelectric detector of a light splitting system, an optical accessory and the like, the measurement system is complex, the requirement on the measurement environment is high, the cost is high, the system is widely applied to laboratory researches, and the system is difficult to apply in the field of agricultural production.

In the aspect of portable instrument research, the SPAD-502 chlorophyll meter is a contact type nondestructive active remote sensing monitoring instrument, and can rapidly and nondestructively detect the chlorophyll content of plant leaves in the field. However, the SPAD instrument uses double light sources to measure the reflectivity of the leaf and calculate the vegetation index to invert the nitrogen content, which is not high in precision, and in practical application, is often affected by the variety of crops, the growth period, the growth environment and the like, and a correction curve is required to be established or a calculation method is improved. In addition, SPAD instruments are developed in japan, are expensive in domestic selling price, are widely used in the scientific research field, and are difficult to be widely applied to agricultural production.

Disclosure of utility model

In order to overcome the defects existing in the prior art, the utility model aims to provide portable blade nitrogen content detection equipment, which can realize the detection of the blade nitrogen content.

In order to achieve the above purpose, the technical scheme adopted by the utility model is as follows:

The portable blade nitrogen content detection equipment comprises an upper shell and a lower shell, wherein the upper shell and the lower shell form a shell structure, a reflected light detection probe and a blade clamp are arranged above the shell structure, the blade clamp is covered on the reflected light detection probe, a display screen square hole and a key round hole are sequentially formed in the surface of the upper shell, the display screen square hole is used for installing a result display module, the key round hole is used for installing a key switch module, a supporting plate is arranged at the edges of two sides inside the lower shell, and a PCB limiting hole is formed in the supporting plate;

The shell comprises a lithium battery, a PCB board, an LED and a photodiode; the LEDs and the photodiodes are sequentially arranged; the lithium battery, the PCB board, the display screen and the keys are arranged in a three-layer stacking way, and the whole lithium battery, the PCB board, the display screen and the keys are arranged below the photodiode; the lithium battery is placed in the cavity of the lower shell and clings to the lower shell, and is positioned at the lower layer; the PCB is connected with the lower shell supporting plate through bolts and is positioned at the middle layer; the display screen and the keys are respectively fixed in the square holes of the upper shell display screen and the round holes of the keys and are positioned on the upper layer.

The reflected light detection probe comprises a probe upper cover and a probe base, wherein a collection hole is formed in the center of the surface of the probe upper cover, and the reflected light detection probe is clung to the blade during collection; the probe base is in a shape of a reverse cone, clamping grooves are formed in the upper part of the outer part of the probe base, and LED limiting holes are uniformly distributed on the side surface of the probe base, perpendicular to a bus of the probe base and on the same horizontal line; the bottom is provided with a photodiode mounting hole.

The LEDs are distributed at an included angle of 45 degrees with the blade to be tested and are arranged between the photodiodes and the blade, and the photodiodes are parallel to the surface of the blade and receive reflected light rays on the surface of the blade; the LED and the photodiode are respectively arranged in the LED limiting hole and the photodiode mounting hole of the detection probe.

The LEDs are 6, the LEDs with the different emission wavelengths are distributed in a ring shape, the included angle of each LED is 60 degrees, the LEDs are arranged in the LED limiting holes, and a condensing lens is arranged above each LED limiting hole and aligned with the center of the LED limiting hole for converging LED light; the center of the reflected light detection probe is provided with a photodiode mounting hole for placing a photodiode. When the LED light source is used, the LED light is incident to the leaf surface from the acquisition hole, and the reflected light of the leaf surface is reflected to the photodiode through the acquisition hole, so that the detection of the reflected light signal is completed.

The upper shell is connected with the lower shell through bolts, assembly through holes are formed in four corners of the inner portion of the lower shell, blind holes are formed in the positions, corresponding to the upper shell, of the upper shell, and threaded copper columns are embedded in the blind holes.

The output end of the key switch module is connected with the input end of the processor module, the output end of the processor module is connected with the result display module and the light source module, and the input end of the processor module is connected with the output end of the reflected light detection module;

The processor module is integrated on a PCB board, takes an STM32F103C8T6 singlechip as a core processor, takes charge of overall control of each module, and coordinates other modules to complete detection tasks;

The light source module consists of an MOS switch circuit, an LED array and a constant current driving circuit thereof, wherein the MOS switch circuit and the constant current driving circuit are integrated on a PCB board and drive the LEDs in a constant current mode, so that the stability of a light source signal is ensured;

the key switch module comprises a power switch key and a detection key, the power switch key is integrated on the PCB, the detection key is fixed in the round hole of the upper shell key, and the control equipment is electrified and the activation equipment starts a detection process;

The reflected light detection module comprises a photoelectric signal conversion circuit, a signal amplification circuit and an A/D conversion circuit, receives the reflected light signals on the surface of the blade, converts the light signals into electric signals, and realizes amplification and noise reduction of the electric signals;

And the result display module displays the working state of the equipment by adopting an LED display screen.

The whole equipment is directly powered by a 5V lithium battery to the light source module and the reflecting light module, and the 5V voltage is reduced to 3.3V through the linear voltage stabilizing chip, so that the working voltage required by the working of the processor module is provided.

The utility model has the beneficial effects that:

the detection equipment overall structure comprises a detection probe and an equipment shell, and 6 detection light sources are annularly arranged in the design of the probe, so that the consistency of light source signals is ensured.

The center of the light source and the blade to be measured are distributed at an included angle of 45 degrees, and the photodiode is parallel to the surface of the blade, so that light is incident to the blade surface and reflected to the photodiode, and reflected light signals of the blade are collected.

And the arrangement of the external blade clamp above the probe can avoid stray light from entering and improve the signal-to-noise ratio of detection signals.

Drawings

FIG. 1 is a schematic diagram of the overall wire frame of the hardware circuit of the present utility model.

Fig. 2 is a circuit schematic of the present utility model.

FIG. 3 is a flow chart of the detection of the device of the present utility model.

Fig. 4 is an overall construction view of the apparatus housing of the present utility model.

FIG. 5 is a schematic view of the optical path of the reflected light according to the present utility model.

Fig. 6 is a cross-sectional view of the reflected light detection probe 3 of the present utility model.

Fig. 7 is a schematic diagram of the positions of the photodiode 12 and the LED limiting aperture 16.

Fig. 8 is a schematic view of the collection well 15.

Fig. 9 is a view showing the internal structure of the lower case 2.

Fig. 10 is a cross-sectional view A-A of fig. 9.

Detailed Description

The utility model is described in further detail below with reference to the accompanying drawings.

As shown in fig. 1: the detection equipment hardware circuit integrally comprises a processor module, a light source module, a key switch module, a reflected light detection module and a result display module.

The processor module takes an STM32F103C8T6 singlechip as a core processor, is responsible for overall control of hardware, and coordinates other modules to complete detection tasks;

The light source module consists of an MOS switch circuit, an LED11 array and a constant current driving circuit thereof, and the LED11 is driven in a constant current mode, so that the stability of a light source signal is ensured;

The key switch module comprises a power switch key and a detection key, and is used for controlling the equipment to power up and activating the equipment to start a detection process;

The result display module adopts an LED11 display screen to display the working state of the equipment.

The whole equipment is directly powered by a 5V lithium battery 9 to the light source module and the reflecting light module, and the 5V voltage is reduced to 3.3V through the linear voltage stabilizing chip, so that the working voltage required by the working of the processor module is provided.

As shown in fig. 2: the hardware circuit of the device comprises a power supply circuit, a constant current driving circuit, a MOS switch circuit, a photoelectric signal conversion circuit, a signal amplification circuit, an A/D conversion circuit, an LED11 circuit and a key circuit.

The power supply circuit converts the 5V input voltage into 3V to supply power for the processor. The constant current drive circuit provides a constant drive current for the LED11 by setting the ISET port input resistance to 2.7kΩ, adjusting the output current to 0.67A. The LEDs 11 are LED11 beads.

The MOS switch circuit controls the LED11 to be opened and closed, the grid electrode is connected to an I/O interface of the STM32F103C8T6 singlechip, when the I/O interface outputs high level, the drain electrode and the source electrode of the MOSFET are conducted, the current generated by the constant current drive circuit flows into the LED11, and the LED11 is lightened.

The input voltage of the photoelectric signal conversion circuit is 5V, the input end is connected with a capacitor to eliminate high-frequency noise of a power supply signal, the anode of a photodiode 12SGPN185 in the circuit is connected with a sampling resistor R2 with the resistance value of 1kΩ in series, and the voltage of the sampling resistor is sampled during detection to realize photoelectric signal conversion.

The signal amplifying circuit amplifies weak electric signals by adopting a method circuit of in-phase proportional operation amplification, and inputs and outputs are connected with decoupling capacitors C4 and C6 with the value of 0.1 mu F, so that the effects of reducing source impedance, reducing power supply noise and increasing operational amplifier stability are achieved, signal quality is improved, and normalization is completed. In the figure, R4 is a feedback resistor with a resistance value of 5kΩ, and R5 is a reverse-end external resistor with a resistance value of 1kΩ, so that the gain coefficient of the circuit signal is 6. The A/D conversion circuit converts the electric signal by adopting an ADS1115 high-precision analog-to-digital conversion chip, P5 is an input port of the voltage processed by the amplifying circuit, the input voltage is 5.0V, the processed digital signal is communicated with the singlechip by using an I2C interface, the I2C bus consists of SDA and SCL, the SDA carries data, and the SCL provides a clock. The SDA and the SCL are respectively connected with the pull-up resistors R6 and R8, so that the SDA and the SCL are high level in the idle period of the bus, and the false start caused by external interference is prevented. All data is transferred in 8 bits over the I2C bus. The LED11 circuit of the display module has an input voltage of 3.3V and is communicated with the core processor through an I2C interface. The input voltage of the key circuit is 5.0V, and the key circuit is used for controlling the equipment to start and activate the equipment detection process.

As shown in fig. 3: the equipment detection flow of the utility model is as follows:

Firstly, initializing equipment, powering up an equipment hardware circuit after a power switch is pressed, and initializing an IO interface of an STM32F103C8T6 singlechip; the LED11 display screen displays characters and prompts the equipment to be electrified, and the detection flow can be executed. The STM32F103C8T6 singlechip detects the key state, and if the key is pressed, the reflected light detection flow is started. STM32F103C8T6 singlechip drives first LED11 to turn on 500ms. And the ADS1115 chip collects voltage signals at two ends of a sampling resistor R2 in the photoelectric signal conversion circuit for 10 times, and transmits the average value to the STM32F103C8T6 singlechip for storage, and the LED11 is turned off. And repeating the detection process until the 6 th LED11 is turned off, calculating the nitrogen content by using a fitting formula, and displaying the detection result on the LED11 display screen. The fitting formula is:

N＝-877.27λ₅₃₀-330.59λ₆₈₀+268.99λ₇₀₅-14λ₇₅₀+60.77λ₈₄₅+46.69λ₉₇₀+135.19

where N is the nitrogen content and λ is the specific wavelength reflectivity.

As shown in fig. 4: the whole structure of the device comprises a reflected light detection probe 3, a device shell and a blade clamp 4;

The reflected light detection probe 3 can ensure that the light of each LED11 is effectively emitted to the surface of the blade to be detected, and the photoelectric sensor is utilized to receive the reflected light signals, so that the external light is prevented from entering and the influence of the direct light of the light source on the detection process is reduced. The equipment shell is designed to be convenient for a user to carry and use, the upper shell 1 is provided with a display screen square hole 5 and a key round hole 6, and the inner space of the shell is used for placing a lithium battery 9, a PCB 10, an LED11 and a photoelectric sensor. The blade clamp 4 is used for clamping the blade, manufacturing implies a detection environment, and the influence of ambient light on detection precision is reduced.

As shown in fig. 5: the LEDs 11 are arranged at an included angle of 45 degrees with the blade to be tested and are arranged between the photodiodes 12 and the blade, and the photodiodes 12 are parallel to the surface of the blade and receive reflected light rays on the surface of the blade. The LED11 and the photodiode 12 are mounted in the LED limiting hole 16 and the photodiode 12 mounting hole of the inspection probe, respectively, as shown in fig. 5.

As shown in fig. 6-8: the LEDs 11 with 6 different emitted light wavelengths are distributed in a ring shape, the included angle of each LED11 is 60 degrees, and the LEDs are arranged in the LED limiting holes 16. A condensing lens is disposed above each LED limiting hole 16 for condensing the light of the LED 11. The center of the probe is a mounting hole of the photodiode 12 for placing the photodiode 12. When in use, the light of the LED11 is incident to the leaf surface from the acquisition hole 15, and the reflected light of the leaf surface is reflected to the photodiode 12 through the acquisition hole, so that the detection of the reflected light signal is completed.

As shown in fig. 9 and 10: the internal structure of the lower case 2 is shown in the figure. The inner components are arranged in a three-layer laminated mode so that the inner space can be utilized to the greatest extent, and the length of the shell is reduced. The battery is placed at the lowest layer and is clung to the lower shell 2, and a battery charging hole is formed in the lower shell 2. Referring to the size of the PCB 10, four supporting plates 7 are designed on the lower case 2 for supporting the PCB 10, four holes on the supporting plates 7 are limiting holes of the PCB 10, and the PCB 10 is placed in the middle layer. The button and the screen are tightly attached to the upper shell 1, are arranged on the uppermost layer, and are arranged on the square hole 5 of the display screen and the round hole 6 of the key. Four positions of the lower shell 2 are reserved with shell assembly through holes, four holes are reserved at the same position of the upper shell 1, and threaded copper columns are embedded for assembling the upper shell 2 and the lower shell 2. The torsion spring mounting hole on the outer side of the lower case 2 is used to fix the blade clamp 4 and mount the torsion spring so that it can clamp the blade.

The device selects the narrow-band LED11 beads when detecting the light source selection, and has the advantages of high light source efficiency, long service life, low power consumption, pure light color, narrow spectrum range, low heat, short response time, capability of covering partial areas on the surface of the blade at a proper distance, and contribution to detection work. When the photodiode 12 is selected, the photodiode 12SGPN MQ silicon photodiode 12 is selected as a photoelectric sensor of the device for signal acquisition, the photosensitive area is 10mm multiplied by 10mm, the spectral response range is 320 nm-1050 nm, the dark current is less than 8nA, and the device has stable performance, high conversion efficiency and good linearity.

The processor selects STM32F103C8T6 singlechip as the core processor of the device. The single chip microcomputer is a 32-bit microcontroller with 64K byte flash memory based on ARM core, the highest working frequency can reach 72MHz, the single chip microcomputer has a wide power supply range of 2.0-3.6V, can realize single-period multiplication and hardware division, has low power consumption modes of sleep, shutdown, standby and the like, has 37 quick I/O interfaces, 2I 2C interfaces and 2 SPI interfaces, and has the advantages of high processing speed, large address space, multiple stored programs and abundant peripheral equipment. The power module selects the 5V polymer lithium battery 9 as the power supply of the equipment, has the advantages of long service life, low self-discharge rate, light weight, environmental protection, simple battery structure, convenient carrying, simple and easy charging and discharging operation and little influence from the external environment, and is the best choice for supplying power to the equipment.

When the power supply circuit is designed, the low-dropout linear regulator LD1117 is selected to convert the output voltage of the lithium battery 9, and output 3.3V voltage to supply power for the processor. The output voltage of the polymer lithium battery 9 is 5V, and the power can be directly supplied to the light source module and the reflecting light module. When the constant current driving circuit is designed, a CN5711 constant current driving chip is selected to provide constant current for the light source, so that the stability of the brightness of the light source is ensured, and the robustness of the detection equipment is improved. When the MOS switch circuit is designed, the 5N10MOSFET is adopted to control the LED11 to be turned on or off, the input capacitance and the output capacitance are lower, the Ciss is 206pf, the output capacitance Coss is 29pf, the reverse transmission capacitance Crss is 1.4pf, and the requirement of high-speed switching is met. The static drain-source on-resistance of the 5N10MOSFET is 110mΩ, and the low power consumption is achieved. The photoelectric signal conversion circuit realizes the conversion from the optical signals reflected by the blades to the electric signals, and by setting SGPN to the light guide mode operation mode of the photodiode 12, when the light irradiates on the PN junction, the two ends of the PN junction generate electromotive force, and a certain current and voltage are output between the electrodes. The signal amplifying circuit adopts an OPA350UA precision amplifier to amplify the input electric signal for the A/D converting circuit to collect the voltage. The A/D conversion circuit converts the electric signal by adopting an ADS1115 analog-to-digital conversion chip, converts the analog quantity into a digital quantity, the chip is a 16-bit high-precision low-power-consumption analog-to-digital converter compatible with I2C, the acquisition voltage signal range is +/-0.256 to +/-6.144V, a low-drift voltage reference and an oscillator are adopted, the size is small, the acquisition precision is high, the power consumption is low, and the equipment requirement is met. The result display module adopts an LED11 display screen to display the working state and the detection result of the equipment, the input voltage is 3.3V, and the input voltage is communicated with the core processor through an I2C interface. The input voltage of the key circuit is 5.0V, and the key circuit is used for controlling the equipment to start and activate the equipment detection process. Proper wire widths are selected according to functions (such as power lines and signal lines) of the circuit module, separation of the signal lines and the power lines is noted, signal lines are prevented from crossing during wiring, the length consistency of the signal lines is ensured as much as possible, and the wiring quality and reliability are improved to complete the design of the PCB 10.

The working principle of the utility model is as follows:

The device is designed according to the principle of absorption and reflection of light by plant leaves, and pigments such as chlorophyll, carotenoid and the like in the plant leaves can absorb light with specific wavelength and reflect light with other wavelengths. The reflectivity of the light with different wavelengths on the blade is jointly influenced by plant pigment and the blade structure to scatter and reflect the light, so that different reflection spectrum characteristics are shown, and therefore, the reflected light signals contain parameter information closely related to the physiological quantity content and the property of the blade. The characteristic wavelength highly related to the nitrogen content of the blade is selected as a light source of the detection device, when a detection switch key is pressed, the light source with specific wavelength is circularly lightened, light is reflected or scattered by the surface of the blade and enters the photodiode 12, the photodiode 12 generates saturated leakage current, an optical signal is converted into an electric signal Vi through a series sampling resistor and is input into a precision operational amplifier OPA350UA, the gain coefficient of the operational amplifier is 6, and the electric signal Vi is amplified by 6 times and then output as Vo. Since the output voltage signal Vo is an analog signal, it is input to the ADS1115 chip to be converted into a digital signal for output, and is transmitted to the core processor STM32F103C8T6 through the I2C protocol. And after receiving the reflected light signals of the blades under the 6 characteristic light sources, the core processor calls a detection model, calculates the nitrogen content value of the blades, and transmits the nitrogen content value to the LED11 display screen through an I2C protocol to display the detection result.

Claims

1. The portable blade nitrogen content detection equipment is characterized by comprising an upper shell (1) and a lower shell (2), wherein the upper shell (1) and the lower shell (2) form a shell structure, a reflected light detection probe (3) and a blade clamp (4) are arranged above the shell structure, the blade clamp (4) is covered on the reflected light detection probe (3), a display screen square hole (5) and a key round hole (6) are sequentially formed in the surface of the upper shell (1), the display screen square hole (5) is used for installing a result display module, the key round hole (6) is used for installing a key switch module, support plates (7) are arranged at edges of two sides inside the lower shell (2), and PCB limiting holes (8) are formed in the support plates (7);

the shell comprises a lithium battery (9), a PCB (10), an LED (11) and a photodiode (12); the LED (11) and the photodiode (12) are sequentially arranged; the lithium battery (9), the PCB (10) and the display screen and the keys are arranged in a three-layer stacking way, and the whole lithium battery is arranged below the photodiode (12); the lithium battery (9) is placed in the cavity of the lower shell (2) and clings to the lower shell (2) and is positioned at the lower layer; the PCB (10) is connected with the support plate (7) of the lower shell (2) through bolts and is positioned in the middle layer; the display screen and the keys are respectively fixed in the square holes (5) of the display screen and the round holes (6) of the keys of the upper shell (1) and are positioned at the upper layer.

2. The portable blade nitrogen content detection device according to claim 1, wherein the reflected light detection probe (3) comprises a probe upper cover (13) and a probe base (14), a collection hole (15) is formed in the center of the surface of the probe upper cover (13), and the reflected light detection probe is tightly attached to the blade during collection; the probe base (14) is in a shape of a reverse cone, clamping grooves are formed in the upper part of the outer part of the probe base, and LED limiting holes (16) are uniformly distributed on the side surface of the probe base, perpendicular to a bus of the probe base and on the same horizontal line; the bottom is provided with a photodiode (12) mounting hole; the LEDs (11) are distributed at an included angle of 45 degrees with the blade to be tested, and are arranged between the photodiodes (12) and the blade, and the photodiodes (12) are parallel to the surface of the blade and receive reflected light rays on the surface of the blade; the LED (11) and the photodiode (12) are respectively arranged in an LED limit hole (16) and a photodiode mounting hole of the detection probe.

3. The portable blade nitrogen content detection device according to claim 2, wherein the LEDs (11) are 6, the LEDs (11) of 6 different emission wavelengths are distributed in a ring, the included angle of each LED (11) is 60 °, the LEDs are installed in the LED limiting holes (16), and a condensing lens is placed above each LED limiting hole (16) and aligned with the center of the LED limiting hole (16) for condensing the light of the LEDs (11); the center of the reflected light detection probe (3) is provided with a photodiode (12) mounting hole for placing the photodiode (12).

4. The portable blade nitrogen content detection device according to claim 1, wherein the upper shell (1) and the lower shell (2) are connected through bolts, assembly through holes are formed in four corners of the inner portion of the lower shell (2), blind holes are formed in corresponding positions of the upper shell (1), and threaded copper columns are embedded in the blind holes.

5. The portable blade nitrogen content detection device according to claim 1, wherein an output end of the key switch module is connected with an input end of the processor module, an output end of the processor module is connected with the result display module and the light source module, and an input end of the processor module is connected with an output end of the reflected light detection module;

the processor module is integrated on a PCB (10) and takes an STM32F103C8T6 singlechip as a core processor;

The light source module consists of an MOS switch circuit, an LED (11) array and a constant current driving circuit thereof, wherein the MOS switch circuit and the constant current driving circuit are integrated on a PCB (10) and drive the LED (11) in a constant current mode;

The key switch module comprises a power switch key and a detection key, wherein the power switch key is integrated on a PCB (10), and the detection key is fixed in a key round hole (6) of the upper shell (1);

The result display module adopts an LED (11) display screen to display the working state of the equipment.