CN221100464U - Near infrared multispectral online automatic measurement equipment suitable for water content of dead combustible on surface of field forest grassland - Google Patents

Abstract

The utility model discloses near-infrared multispectral online automatic measurement equipment suitable for the water content of dead combustible materials on the surface of a field forest grassland, which is characterized in that infrared light is emitted to a measured sample after passing through a four-wavelength filtering rotating wheel, a converging lens is connected with a photoelectric sensor through a thread adjusting mechanism, the received near-infrared light reflected by the measured sample is focused on a photosensitive surface of the photoelectric sensor, and the thread adjusting mechanism changes the focusing distance set by the lens by adjusting the relative distance between the converging lens and the photoelectric sensor; a fixed optical filter is inserted in the optical path between the converging lens and the photoelectric sensor; the control circuit is electrically connected with the photoelectric sensor, is communicated with the outside, receives an external time sequence control signal and generates a time sequence waveform, and controls the photoelectric sensor to work and read the induction signal value. The utility model can inhibit the interference of ambient stray light, improves the reliability of the system, and is more suitable for long-term use in field environment.

Description

Near infrared multispectral online automatic measurement equipment suitable for water content of dead combustible on surface of field forest grassland

Technical Field

The utility model relates to the application field of photoelectric measurement technology in forest grassland fire hazard early warning and monitoring, in particular to near infrared multispectral online automatic measurement equipment suitable for the water content of dead combustible on the surface of a field forest grassland.

Background

The water content of the dead combustible on the surface of the forest influences the probability, the propagation rate, the radiation efficiency and the energy release of the fire. The water content of dead combustible on the surface of the earth is an important basis for accurately assessing forest fire risk and is considered as a key parameter affecting fire behavior change. Therefore, on-line monitoring of the moisture content of forest combustibles, especially dynamic prediction of the moisture content of ground dead combustibles, has become the core of a forest fire risk rating system.

The dead combustible material on the surface of the forest grassland has complex composition, loose and irregular structure, takes a flat shape or a long needle shape as a main shape, and exists on the surface of the forest grassland in a lying shape, so that the forest grassland has large surface area, fully contacts with air, and has better consistency of the internal water content and the surface water content. The dead combustible on the surface of the earth is dynamic from generation to degradation, and the morphology and structure are correspondingly changed in different stages. The boundaries of combustibles, humus layers and soil are unclear.

At present, the widely applied water content measuring method comprises the following steps: gravimetric, dielectric constant (including specifically frequency domain reflectometry FDR and time domain reflectometry TDR), microwave, and near infrared reflectometry. The gravimetric method is an internationally accepted standard method, and has accurate measurement results, but needs to be sampled and dried for a long time, has a certain destructiveness on the sample, and is not suitable for long-term fixed-point continuous monitoring. The TDR and the FDR are mainly used for measuring the water content of soil, have higher measuring precision, have no radioactivity, can realize and automate long-term fixed-point observation, but both methods need to arrange probes in the field, which are in direct contact with detected objects, and are not suitable for measuring the water content of dead combustible objects on the surface of a forest grassland in the natural state.

The microwave method is suitable for measuring the average water content of substances in a volume (with fixed quantity), has high measurement accuracy and high speed, can be used for long-term online monitoring, but the combustible substances on the surface of the forest grassland are loose and irregular in structure in the natural state, the quantity and the density of the combustible substances can be changed, the limit of combustible substances, a littering layer, a humus layer and soil is unclear and dynamically changed, and microwaves can penetrate into the soil, so that the microwaves are not suitable for nondestructive and long-term online measurement of the water content of the combustible substances on the surface of the forest grassland in the natural state.

The near infrared reflection method utilizes the principle that near infrared wavelength energy can be absorbed by water molecules, adopts near infrared wavelength (measuring light) with high water absorptivity and near infrared wavelength (reference light) with low water absorptivity to respectively irradiate a sample to be measured, and can invert the water content of the sample by analyzing corresponding different reflection energy changes. The measurement accuracy is affected by the color, the shape and the structure of a measured sample, but forest grassland fire is mainly concerned with the condition that the water content of combustible matters is lower than 35%, chlorophyll, lutein and the like of the combustible matters with the water content are basically completely degraded, the consistency of the color, the shape and the structure is good, and the consistency of measured data is good after the data calibration of a fixedly installed comprehensive station is finished. The near infrared spectrometry avoids the sampling process, and is very suitable for rapid, nondestructive and non-contact continuous on-line detection of the water content of the dead combustible in the forest and grassland.

Light sources common to near infrared light sources at present are halogen lamps, lasers and LED light sources. The laser has complex light path, complex structure and high price; the single lamp bead of the LED light source is difficult to achieve more than 5 watts, special heat dissipation is needed, the natural light interference suppression capability of a working area with natural light is weak, the spectrum is greatly influenced by temperature drift, and the LED light only provides a light source with a wave band below 1600nm at present.

Moisture is particularly obvious for light absorption of a few wavelengths in the near infrared, and can be used for measuring the moisture content in the industrial field. The reference light is used as a reference for correcting interference factors of external or material composition changes, so that the measurement degree and accuracy of the water content are improved, and theoretically, the more multiple bands are used as references, the less influence is exerted on the measurement of the instrument.

At present, a photoelectric sensor mainly comprises a lead sulfide (Pbs) infrared detector and an indium gallium arsenide (InGaAs) infrared detector, and the lead sulfide (Pbs) infrared detector is applied to gas detection, optical temperature measurement, photometer, medical gas analysis and the like; the InGaAs infrared detector has excellent comprehensive performance, high sensitivity, wide band coverage, high resolution, high speed, low noise and other advantages.

The near infrared reflection method is used for measuring the water content, because of the technical characteristics of near infrared light, the ambient stray light and meteorological factors directly influence near infrared measurement accuracy, for example, the larger the total solar radiation is, the faster the water content value of the surface combustible is reduced by heat, and meanwhile, the photoelectric energy value detected by a near infrared water content sensor is increased by the energy of light with specific wavelength, so that the measured water content value is reduced, the photoelectric energy value is required to be corrected by a method, the measured value is optimized, and the measurement accuracy is improved, so that the method can meet the service requirement of the field environment under natural light.

Disclosure of utility model

The utility model aims to solve the technical problem of providing near infrared multispectral online automatic measurement equipment suitable for the water content of the dead combustible on the surface of a field forest grassland so as to realize more stable, accurate and rapid online measurement of the water content of the dead combustible on the surface in a natural state.

In order to solve the technical problems, the technical scheme provided by the utility model is as follows: the near infrared multispectral online automatic measurement equipment suitable for the water content of dead combustible substances on the surface of a field forest grassland comprises a rapid replacement light source device, a reinforced power infrared light source, a four-wavelength filtering rotating wheel, a converging mirror, a photoelectric sensor, a light filter, a thread adjusting mechanism, a control circuit, a singlechip, a communication control module, a time sequence control module, a photoelectric sensor driving module and the like. The infrared light source with enhanced power is assembled with a structure for supporting quick disassembly and assembly by the quick replacement light source device, infrared light is emitted to a tested sample after passing through the four-wavelength filtering rotating wheel, the converging lens is connected with the photoelectric sensor through the thread adjusting mechanism, the received near infrared light reflected by the tested sample is focused on a photosensitive surface of the photoelectric sensor, and the thread adjusting mechanism changes the focusing distance set by the lens by adjusting the relative distance between the converging lens and the photoelectric sensor; a fixed optical filter is inserted in the optical path between the converging lens and the photoelectric sensor; the control circuit is electrically connected with the photoelectric sensor, is communicated with the outside, receives an external time sequence control signal and generates a time sequence waveform, and controls the photoelectric sensor to work and read the induction signal value.

Preferably, the control circuit comprises a singlechip, a communication control module, a time sequence control module and a detector driving module which are electrically connected with the singlechip;

The communication control module is communicated with the outside, acquires and sets time sequence parameters sampled by the detector, and externally transmits the reference wavelength signal measured value, the measured wavelength signal measured value and the background light signal measured value acquired by the detector driving module to the upper computer;

the time sequence control module generates a specific sampling time sequence waveform according to sampling time sequence parameters and synchronous measurement period signals which are set by the upper computer, and the reference light measurement, the measurement light measurement and the background light measurement are distinguished through time sequence sequencing;

the detector driving module sets the photoelectric sensor in a bias working state, reads out the sensing signal value output by the photoelectric sensor according to the sampling time sequence waveform, and accordingly obtains a reference wavelength signal measured value, a measuring wavelength signal measured value and a background light signal measured value.

Preferably, the device comprises a rapid replacement light source, is a structural member supporting rapid disassembly and assembly, and is convenient for rapid replacement of the infrared light source bulb with enhanced power;

Preferably, the enhanced power infrared light source is a high power halogen broadband infrared lamp;

Preferably, the four-wavelength filtering rotating wheel is a 5-hole filtering rotating wheel with average distribution, wherein the 4-hole precision infrared filter allows the reference light with the valley wavelength close to the measured light wave peak and the pulse of the measured light to alternately pass through the filter, and the 1-hole is opaque, so that any measured light and the reference light cannot pass through, and the photoelectric sensor is ensured to only collect the signals of natural light;

Preferably, the photoelectric sensor is an InGaAs infrared detector, and the sensing wavelength range of the photoelectric sensor is 1300 nm-2000 nm.

Preferably, the filter is a 1300nm to 2000nm bandpass filter that defines the photosensor to only sense infrared light energy between the reference wavelength 1300nm and the measurement wavelength 2000 nm.

Preferably, the timing control module measures a rising edge of the periodic signal as the synchronization signal; after the rising edge comes, sampling the reference optical signal for N times, and then sampling the measuring optical signal for N times, wherein N is a positive integer greater than 6.

Compared with the prior art, the utility model has the advantages that: the utility model adopts an enhanced power infrared light source supporting quick disassembly and assembly, a fixed bandpass filter selects a response wavelength range, limits the response wavelength range of a photoelectric sensor between a reference wavelength and a measurement wavelength, selects a plurality of light with the most moisture sensitive wavelength as measurement light, takes valley wavelength light close to a measurement light wave peak as reference light, takes natural light as background light, and carries out certain correction on measurement signals and reference signals; receiving by using an InGaAs infrared detector; the time sequence working mode is adopted to distinguish the reference wavelength sampling, the measurement wavelength sampling and the background light sampling, so that the ambient parasitic light interference can be restrained, and the method is more suitable for being used in the field environment.

Drawings

Fig. 1 is a diagram showing the composition of a near infrared measurement system.

Fig. 2 is a control flow diagram of the near infrared measurement system.

Fig. 3 is a near infrared measurement sampling timing diagram.

Fig. 4 is a near infrared measurement workflow diagram.

As shown in the figure: 1. the device comprises a light source device, a reinforced power infrared light source, a four-wavelength filtering rotating wheel, a converging lens, a photoelectric sensor, a light filter, a thread adjusting mechanism, a control circuit, a singlechip, a communication control module, a timing sequence control module, a detector driving module and a detector driving module, wherein the light source device is rapidly replaced, the power infrared light source is reinforced, the light source is powered up, the light source is filtered through the four-wavelength filtering rotating wheel, the converging lens is powered up, the light source is converged, the light source is powered up, the light source is focused through the four-wavelength filtering rotating wheel, the light source is focused through the converging lens, the light source is powered up, the photoelectric sensor is powered up, the light source is powered down, the light source is powered up, the light source is screwed by.

Detailed Description

In the description of the present utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", "vertical", "circumferential", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

In the present utility model, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

The near infrared multispectral on-line automatic measuring equipment for the water content of the dead combustible on the surface of the wild forest grassland is described in further detail below with reference to the accompanying drawings.

The present utility model will be described in detail with reference to fig. 1 to 4.

The near infrared multispectral online automatic measurement equipment suitable for the water content of dead combustible substances on the surface of a field forest grassland comprises a rapid replacement light source device 1, a reinforced power infrared light source 2, a four-wavelength light filtering rotating wheel 3, a converging lens 4, a photoelectric sensor 5, a light filter 6, a thread adjusting mechanism 7, a control circuit 8, a singlechip 9, a communication control module 10, a time sequence control module 11 and a photoelectric sensor driving module 12. The infrared light source 2 with enhanced power is assembled with the structure for supporting quick disassembly and assembly by the quick replacement light source device 1, infrared light is emitted to a tested sample after passing through the four-wavelength filtering rotating wheel 3, the converging lens 4 is connected with the photoelectric sensor 5 through the thread adjusting mechanism 7, the received near infrared light reflected by the tested sample is focused on a photosensitive surface of the photoelectric sensor 5, and the thread adjusting mechanism 7 changes the focusing distance set by the lens by adjusting the relative distance between the converging lens 4 and the photoelectric sensor 5; a fixed optical filter 6 is inserted in the optical path between the converging lens 4 and the photoelectric sensor 5; the control circuit 8 is electrically connected with the photoelectric sensor 5, and is in communication with the outside, receives an external time sequence control signal and generates a time sequence waveform, and controls the photoelectric sensor 5 to work and read the sensing signal value.

The control circuit 8 comprises a singlechip 9, a communication control module 10, a time sequence control module 11 and a detector driving module 12 which are electrically connected with the singlechip; the communication control module 10 communicates with the outside, acquires and sets time sequence parameters sampled by the photoelectric sensor, and externally transmits the reference wavelength signal measured value, the measured wavelength signal measured value and the background light signal measured value acquired by the detector driving module 12 to the upper computer; the time sequence control module 11 generates specific sampling time sequence waveforms according to sampling time sequence parameters and synchronous measurement period signals set by the upper computer, and distinguishes reference light measurement, measurement light measurement and background light through time sequence sequencing; the detector driving module 12 sets the photosensor 5 in a bias operation state, and reads out the sensing signal value output by the photosensor 3 according to the sampling timing waveform, thereby obtaining a reference wavelength signal measurement value, a measurement wavelength signal measurement value, and a background light signal measurement value.

The rapid replacement light source device 1 is a structural member supporting rapid disassembly and assembly, and is convenient for rapidly replacing the bulb of the reinforced power infrared light source 2;

the enhanced power infrared light source 2 is a high power halogen broadband infrared lamp;

The four-wavelength filtering rotating wheel 3 is a 5-hole filtering rotating wheel with average distribution, wherein a 4-hole precision infrared filter allows reference light (valley wavelength light close to a measuring light wave peak) and pulses of measuring light to alternately pass through the filter 6, and the other 1 hole is opaque, so that any measuring light and the reference light cannot pass through, and the photoelectric sensor 5 is ensured to only collect signals of natural light;

The photoelectric sensor 5 is an InGaAs infrared detector, and the induction wavelength range is 1300 nm-2000 nm;

the optical filter 6 is a band-pass optical filter between 1300nm and 2000nm, and the optical filter is used for limiting the photoelectric sensor to only sense infrared light energy between 1300nm of reference wavelength and 2000nm of measurement wavelength;

The timing control module 11 measures the rising edge of the periodic signal as a synchronous signal; after the rising edge comes, sampling the reference optical signal for N times, and then sampling the measuring optical signal for N times, wherein N is a positive integer greater than 6.

The utility model relates to a multispectral (near infrared) online automatic measuring device for the water content of dead combustible on the surface of a field forest grassland, which comprises the following specific working processes:

The near infrared detection system consists of a photoelectric sensor 5, a converging lens 4, an optical filter 6 and a control circuit 8; wherein the photoelectric sensor 5 is an InGaAs infrared detector, and the induction wavelength range is 1300 nm-2000 nm.

The converging lens 4 focuses the received near infrared light reflected by the sample to be measured onto the photosensitive surface of the aforementioned photosensor 5. The converging lens 4 used in the utility model is a K9 glass lens with the diameter of 50mm and the focal length of 50 mm. The converging lens 4 is designed with a screw thread adjusting mechanism 7, and the focusing distance set by the lens can be changed by adjusting the relative distance between the converging lens 4 and the photoelectric sensor 5, so that the signal value of a target on a 50cm measuring distance sensed by the photoelectric sensor 5 can be maximized.

A fixed filter 6 is inserted in the optical path between the receiving lens and the photosensor 5. The type of the optical filter 6 is 1300 nm-2500 nm, the photoelectric sensor 5 is limited to only sense infrared light energy between 1300nm of reference wavelength and 2000nm of measurement wavelength, stray light which is not in the range is filtered, and interference of ambient light is restrained.

The control circuit 8 is a circuit board based on an STM32 singlechip 9 chip. The control circuit 8 comprises a communication control module 10, a time sequence control module 11, a detector driving module 12 and other circuit structures.

The communication control module 10 of the control circuit 8 communicates with the outside, acquires and sets the time sequence parameters of the photoelectric sensor sampling, and transmits the reference wavelength signal measurement value, the measurement wavelength signal measurement value and the background light signal measurement value acquired by the photoelectric sensor driving module 12 to the upper computer.

The timing control module 11 of the control circuit 8 generates specific sampling timing waveforms according to the sampling timing parameters set by the upper computer and the synchronous measurement period signals, and can distinguish the reference light measurement, the measurement light measurement and the background light measurement through the timing sequence. In the utility model, the rising edge of a measurement periodic signal is used as a synchronous signal; after the rising edge arrives, N reference optical signal samples (n=10 in the present utility model) are performed first, then N measurement optical signal samples (n=10 in the present utility model) are performed, and finally N background optical signal samples (n=10 in the present utility model) are performed.

The detector driving module 12 of the control circuit 8 sets the photosensor 5 in a suitable bias operating state, and reads out the sensing signal value output by the photosensor 5 according to the sampling time sequence waveform, thereby obtaining the reference wavelength signal measurement value, the measurement wavelength signal measurement value and the background light signal measurement value.

The utility model adopts a fixed band-pass filter 6 to select a response wavelength range; the response wavelength range of the photoelectric sensor is limited between the reference wavelength and the measurement wavelength, so that the ambient parasitic light interference can be restrained, the reliability of the system is improved, and the photoelectric sensor is more suitable for long-term use in a field environment.

The utility model adopts a time sequence working mode to distinguish reference wavelength sampling, measurement wavelength sampling and background light sampling.

The utility model adopts an InGaAs infrared detector for receiving; the structure is simple, the product volume is small, the system reliability is improved, and the device is more suitable for long-term use in a field environment.

The utility model and its embodiments have been described above with no limitation, and the actual construction is not limited to the embodiments of the utility model as shown in the drawings. In summary, if one of ordinary skill in the art is informed by this disclosure, a structural manner and an embodiment similar to the technical solution should not be creatively devised without departing from the gist of the present utility model.

Claims (8)

1. Near-infrared multispectral online automatic measurement equipment suitable for water content of dead combustible on surface of field forest grassland, and is characterized in that: the device comprises a rapid replacement light source device (1), an enhanced power infrared light source (2), a four-wavelength filtering rotating wheel (3), a converging lens (4), a photoelectric sensor (5), a light filter (6), a thread adjusting mechanism (7), a control circuit (8), a singlechip (9), a communication control module (10), a time sequence control module (11) and a detector driving module (12); the infrared light source (2) with enhanced power is assembled with the rapid replacement light source device (1) to support rapid disassembly and assembly, infrared light is emitted to a tested sample after passing through the four-wavelength filtering rotating wheel (3), the converging lens (4) is connected with the photoelectric sensor (5) through the thread adjusting mechanism (7), received near infrared light reflected by the tested sample is focused on a photosensitive surface of the photoelectric sensor (5), and the thread adjusting mechanism (7) changes the focusing distance set by the lens by adjusting the relative distance between the converging lens (4) and the photoelectric sensor (5); a fixed optical filter (6) is inserted in the light path between the converging lens (4) and the photoelectric sensor (5); the control circuit (8) is electrically connected with the photoelectric sensor (5), is communicated with the outside, receives an external time sequence control signal and generates a time sequence waveform, and controls the photoelectric sensor (5) to work and read the induction signal value.

2. The near infrared multispectral online automatic measurement device for the water content of dead combustible on the surface of a field forest grassland according to claim 1, wherein the device comprises: the control circuit (8) comprises a singlechip (9), a communication control module (10), a time sequence control module (11) and a detector driving module (12), wherein the communication control module (10), the time sequence control module (11) and the detector driving module are electrically connected with the singlechip;

The communication control module (10) is communicated with the outside, acquires and sets time sequence parameters sampled by the photoelectric sensor, and externally transmits the reference wavelength signal measured value, the measured wavelength signal measured value and the background light signal measured value acquired by the detector driving module (12) to the upper computer;

The time sequence control module (11) generates specific sampling time sequence waveforms according to sampling time sequence parameters and synchronous measurement period signals set by the upper computer, and the reference light measurement, the measurement light measurement and the background light measurement are distinguished according to time sequence sequences;

The detector driving module (12) sets the photoelectric sensor (5) in a bias working state, and reads out the sensing signal value output by the photoelectric sensor (5) according to the sampling time sequence waveform, so as to obtain a reference wavelength signal measurement value and a measurement wavelength signal measurement value.

3. The near infrared multispectral online automatic measurement device for the water content of dead combustible on the surface of a field forest grassland according to claim 2, wherein the device comprises: the device comprises a rapid replacement light source device (1) which is a structural member supporting rapid disassembly and assembly, and is convenient for rapid replacement of the bulb of the infrared light source (2) with enhanced power.

4. A near infrared multi-spectrum on-line automatic measuring device for water content of dead combustible on surface of field forest grassland according to claim 3, characterized in that: the enhanced power infrared light source (2) is a high power halogen broadband infrared lamp.

5. The near infrared multispectral online automatic measurement device for the water content of dead combustible on the surface of a field forest grassland according to claim 1, wherein the device comprises: the four-wavelength filtering rotating wheel (3) is a 5-hole filtering rotating wheel with average distribution, wherein a 4-hole precision infrared filter allows pulses of measuring light with a wavelength of 1450nm, measuring light with a valley wavelength reference light with a wavelength of 1940nm, and measuring light with a valley wavelength reference light with a wavelength of 1940nm, wherein the measuring light with a wavelength of 1450nm and the valley wavelength reference light with a wavelength of 1940nm are alternately transmitted through the filter (6), and in addition, 1 hole is opaque, so that any measuring light and reference light cannot pass, and the photoelectric sensor (5) is ensured to only acquire signals of natural light.

6. The near infrared multispectral online automatic measurement device for the water content of dead combustible on the surface of a field forest grassland according to claim 2, wherein the device comprises: the photoelectric sensor (5) is an InGaAs infrared detector, and the induction wavelength range of the photoelectric sensor is 1300 nm-2000 nm.

7. The near infrared multispectral online automatic measurement device for the water content of dead combustible on the surface of a field forest grassland according to claim 1, wherein the device comprises: the filter (6) is a band-pass filter between 1300nm and 2000nm, which defines that the photosensor (5) only senses infrared light energy between a reference wavelength of 1300nm and a measurement wavelength of 2000 nm.

8. The near infrared multispectral online automatic measurement device for the water content of dead combustible on the surface of a field forest grassland according to claim 2, wherein the device comprises: the time sequence control module (11) takes the rising edge of the measured periodic signal as a synchronous signal; after the rising edge comes, sampling the reference optical signal for N times, and then sampling the measuring optical signal for N times, wherein N is a positive integer greater than 6.