CN111474590B - Non-contact electromagnetic detection system and method for dangerous liquid - Google Patents
Non-contact electromagnetic detection system and method for dangerous liquid Download PDFInfo
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- CN111474590B CN111474590B CN202010374645.7A CN202010374645A CN111474590B CN 111474590 B CN111474590 B CN 111474590B CN 202010374645 A CN202010374645 A CN 202010374645A CN 111474590 B CN111474590 B CN 111474590B
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- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
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Abstract
The invention relates to the technical field of safety detection, in particular to a non-contact electromagnetic detection system and a non-contact electromagnetic detection method for dangerous liquid. The hardware part comprises a signal generating circuit, a transmitting antenna, a receiving antenna, a signal receiving and demodulating circuit, a digital signal sampling and processing circuit and a related control circuit, and can realize reflected wave signal detection and high spatial resolution. The receiving and transmitting antenna is an antenna with high gain, narrow beam and low side lobe, and can realize effective detection of reflected wave signals, reduce clutter and realize high spatial resolution. The software part realizes the spatial reflection spectrum peak detection, the reflected signal intensity detection, the far-field electromagnetic wave system correction and the signal compensation of high spatial resolution by an algorithm. The invention establishes a multi-feature model and an algorithm theory to identify flammable and explosive liquid by detecting two features of the reflection intensity of the liquid to electromagnetic waves and the reflection spectrum peak, thereby realizing the safety check of the non-contact type liquid carried by a human body.
Description
Technical Field
The invention relates to the technical field of safety detection, in particular to a non-contact electromagnetic detection system and a non-contact electromagnetic detection method for dangerous liquid.
Background
In recent years, terrorist attacks around the world have severely threatened human lives and properties, especially in traffic-intensive areas, where terrorist attacks are more on the rise. In order to effectively suppress terrorist attacks and ensure the life safety of passengers and the operation safety of public transportation, safety detection needs to be implemented at public transportation stations such as subways, light rails, trains, buses and the like. Existing X-ray security inspection instruments are capable of performing security checks on items in passenger backpacks and trunks, yet require manual security checks on threat items concealed within the passenger's clothing. Terahertz (THz) technology has been used for security inspection in recent years, and is classified into an active type and a passive type, as shown in fig. 1. The active terahertz technology is used for imaging passengers in real time to detect hidden threats; the terahertz security check instrument used commercially in China at present mainly adopts a passive detection means, and passive detection can only discover foreign matters hidden in passenger clothes and cannot realize fine identification of the foreign matters. Whether the terahertz imaging security inspection instrument is an active or passive terahertz imaging security inspection instrument, whether the liquid is flammable and explosive liquid represented by pure ethanol, methanol, gasoline, banana oil and the like cannot be identified at the present stage. The detection technology based on the Raman spectrum utilizes the difference of molecular energy levels among different liquid substances and the difference of scattering spectra generated by the liquid irradiated by laser to detect the liquid. The detection technology based on the raman spectrum has the advantages of high accuracy, but needs a laser light source, has certain danger and is easily interfered by the external environment. The detection technology based on X-ray utilizes the different attenuation degrees of X-ray passing through the liquid to obtain the ordinal number and density of atoms, so as to identify the liquid. The X-ray detector has the advantages that the X-ray detector can penetrate through plastic, glass and even metal, but the X-ray detector is extremely high in cost and can cause damage to human bodies when being directly applied to human body detection.
Therefore, the existing detection technology can not detect flammable and explosive liquid in a safe and non-contact mode, and the safety detection and identification aiming at the flammable and explosive liquid become a research focus and an urgent need for attacking technology for public safety high-precision detection.
Disclosure of Invention
Aiming at the defects of the prior art, the invention discloses a non-contact electromagnetic detection system and a non-contact electromagnetic detection method for dangerous liquid, which are used for identifying flammable and explosive liquid by detecting two characteristics of the reflection intensity of the liquid to millimeter waves and a reflection spectrum peak by utilizing a millimeter wave technology lower than a terahertz frequency band, and realizing the safety check of the liquid carried by passengers.
The invention is realized by the following technical scheme:
in a first aspect, the invention discloses a non-contact electromagnetic detection system for hazardous liquid, which is provided with a hardware system and a software system, wherein the hardware system is a radar system with a distance measurement function, the software system is software detection comprising reflection intensity detection and reflection space spectrum peak detection, and during detection, the hardware system acquires millimeter wave echo data of an object to be detected, and realizes non-contact detection through detection and analysis of the software system.
Furthermore, the radar system comprises a signal generating circuit, a transmitting antenna, a receiving antenna, a signal receiving and demodulating circuit, a digital signal sampling and processing circuit and an associated control circuit.
Furthermore, the receiving antenna and the transmitting antenna are both broadband and high-gain antennas.
Furthermore, the beam widths of the receiving antenna and the transmitting antenna are set to be extremely narrow, clutter caused by target reflection from the surrounding environment is reduced, and millimeter wave detection precision and stability are improved.
Furthermore, the working frequency range is a millimeter wave frequency range, but also includes a microwave frequency range and a terahertz frequency range.
In a second aspect, the present invention discloses a method for non-contact electromagnetic detection of a hazardous liquid, which is implemented by implementing the system for non-contact electromagnetic detection of a hazardous liquid of the first aspect, and the method includes the following steps:
s1, electrifying the radar system, calibrating the system, and entering a state to be detected;
s2, detecting the object to be detected by using a radar system to obtain millimeter wave echo data of the detected object;
s3, analyzing the data in S2 by selecting a reflection space spectrum peak detection method to obtain a detection result;
s4, analyzing the data in S2 by selecting a reflection intensity detection method to obtain a detection result;
s5 comprehensively analyzes the detection results in S3 and S4 to obtain the final conclusion.
Furthermore, the reflection space spectrum peak detection method is characterized in that the characteristic that the electric loss of millimeter waves in water is high is utilized, the receiving antenna only receives echoes reflected by a front wall of the liquid bottle, only a single reflection spectrum peak is generated in space, according to the characteristic that the electric loss of flammable and explosive liquid is low, the millimeter waves can penetrate through the liquid, secondary reflection is generated on the rear wall of the bottle, a double reflection spectrum peak can be generated in space, and the liquid to be detected is judged to be drinking water, dangerous liquid or an empty bottle.
Furthermore, the reflection intensity detection method is characterized in that the dangerous liquid and the water are distinguished by using the fact that the reflection signal of the water is obviously greater than that of the flammable and explosive liquid, and the dangerous liquid and the empty bottle are distinguished by using the fact that the intensity of the secondary reflection signal of the dangerous liquid is obviously less than that of the empty bottle, so that the dangerous liquid is detected, and a measurement result is obtained.
Furthermore, the container material of the article to be detected is a liquid container made of a nonmetal material, and the liquid contained in the container is safe liquid, dangerous liquid or not.
The invention has the beneficial effects that:
1. the detection system of the invention is a non-contact detection mode, and has the advantages of long detection distance, high resolution and low system power consumption.
2. The detection method can detect safe drinks and dangerous liquid, can detect the containing amount of the liquid, has no ionizing radiation, has no ionizing damage to human bodies, and is suitable for any scene.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a background art terahertz current security inspection diagram;
FIG. 2 is a schematic diagram of a non-contact electromagnetic detection system for hazardous liquids;
FIG. 3 is a flow chart of the operation of a non-contact electromagnetic detection system for hazardous liquids;
FIG. 4 is a comparison graph of real and imaginary parts of dielectric constants of different liquids in a millimeter wave frequency band;
FIG. 5 is a schematic illustration of the reflection of millimeter waves by water and flammable and explosive liquids;
FIG. 6 is a millimeter wave reflectance spectrum peak detection plot of drinking water, pure alcohol and empty bottles;
FIG. 7 is a diagram of the reflection spectrum peak detection of common drinks by millimeter wave technology;
FIG. 8 is a diagram of the reflection spectrum peak detection of a hazardous liquid by millimeter wave technology;
FIG. 9 is a graph of the reflected power of millimeter waves versus distance for a hazardous liquid and a control liquid.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The embodiment discloses a non-contact electromagnetic detection system for dangerous liquid, which is provided with a hardware system and a software system, wherein the hardware system is a radar system with a distance measuring function, the software system is software detection comprising reflection intensity detection and reflection space spectrum peak detection, during detection, the hardware system sends millimeter wave signals, millimeter wave echo data of an object to be detected are obtained and preprocessed, and non-contact detection is realized through detection and analysis of the software system.
The radar system comprises a signal generating circuit, a transmitting antenna, a receiving antenna, a signal receiving and demodulating circuit, a digital signal sampling and processing circuit and a related control circuit.
The receiving antenna and the transmitting antenna are both broadband and high-gain antennas. The wave beam width of the receiving antenna and the wave beam width of the sending antenna are extremely narrow, clutter caused by target reflection from the surrounding environment is reduced, and millimeter wave detection precision and stability are improved. The working frequency is a millimeter wave frequency band, but also comprises a microwave frequency band and a terahertz frequency band.
The detection system of the embodiment is in a non-contact detection mode, and has the advantages of long detection distance, high resolution and low system power consumption.
Example 2
The embodiment discloses a non-contact electromagnetic detection method for hazardous liquid, which is implemented by implementing the non-contact electromagnetic detection system for hazardous liquid of the first aspect, and the method comprises the following steps:
s1, electrifying the radar system, calibrating the system, and entering a state to be detected;
s2, detecting the object to be detected by using a radar system to obtain millimeter wave echo data of the detected object;
s3, analyzing the data in S2 by selecting a reflection space spectrum peak detection method to obtain a detection result;
s4, analyzing the data in S2 by selecting a reflection intensity detection method to obtain a detection result;
s5 comprehensively analyzes the detection results in S3 and S4 to obtain the final conclusion.
The method for detecting the reflection space spectrum peak utilizes the characteristic that millimeter waves have high electric loss in water, millimeter wave signals are absorbed by liquid, a receiving antenna only receives echoes reflected by a front wall, only a single reflection spectrum peak is generated in space, the millimeter waves can penetrate through the liquid according to the characteristic that the electric loss of flammable and explosive liquid is low, secondary reflection is generated on the rear wall of a bottle, double reflection spectrum peaks can be generated in space, and the liquid to be detected is judged to be drinking water, dangerous liquid or an empty bottle.
The detection method of the reflection intensity is characterized in that a dangerous liquid and water are distinguished by using that the reflection signal of the water is obviously greater than that of the flammable and explosive liquid, and the dangerous liquid and an empty bottle are distinguished by using that the intensity of the secondary reflection signal of the dangerous liquid is obviously less than that of the empty bottle, so that the dangerous liquid is detected, and a measurement result is obtained.
The container material of waiting to detect article is the liquid container of non-metallic material, and the liquid that holds in the container is safe liquid, dangerous liquid or does not hold.
The detection method of the embodiment can be used for detecting safe drinks and dangerous liquid, can be used for detecting the containing amount of the liquid, has no ionizing radiation, has no ionizing damage to a human body, and is suitable for any scene.
Example 3
The present embodiment discloses an electromagnetic detection system and method for hazardous liquid, and it should be noted that the exemplary embodiment and description thereof in the present embodiment include, but are not limited to, a millimeter wave frequency band, which is only used for explaining and verifying the detection method of the present invention, and is still applicable to other frequency bands, and is not limited to the present invention.
As shown in fig. 2, the system and method for electromagnetic detection of hazardous liquid includes two parts, hardware and software. The hardware part is a continuous wave frequency modulation radar system 1 which comprises a signal generating circuit 2, a transmitting antenna 3, a receiving antenna 4, a signal receiving and demodulating circuit 5, a digital signal sampling and processing circuit 6 and a related control circuit 7. The software part is divided into a reflection intensity detection method 8 and a reflection space spectrum peak detection method 9.
The flow chart of the verification method is shown in fig. 3, the safe drinks such as coca-cola, orange juice, oolong tea, unified milk tea and drinking water can be respectively tested, the result is shown in fig. 6, the dangerous liquid ethanol and methanol are tested, meanwhile, the empty bottle is tested, and the result is shown in fig. 7. Safe drinks can be distinguished from other situations according to the number of spectral peaks in the reflection bispectrum peak image.
It should be noted that safe drinks include, but are not limited to, the above safe drinks, and hazardous liquids include, but are not limited to, methanol and ethanol. The liquid to be detected is only convenient to purchase and verifies the feasibility of the detection method, and the detection method can be used for detecting various liquids.
The curve in fig. 7 is plotted in fig. 8 and compared with the curve in fig. 8, based on the reflection bispectrum peak detection method in combination with the reflection intensity detection method. Since the imaginary part of the relative dielectric constant of methanol is higher than that of ethanol, the attenuation of millimeter waves by methanol is greater than that of ethanol. The intensity of an echo signal (namely a second reflection spectrum peak) of a millimeter wave signal which passes through ethanol and is reflected by the wall side of the rear bottle, passes through the ethanol again and returns to a radar is larger than that of methanol, but the intensity of the second echo signal of the ethanol and the intensity of the second echo signal of the methanol are far smaller than that of an empty bottle. Thus, in fig. 8, it can be seen that the second reflection peak is highest for the empty bottle, and that the second reflection peak for ethanol is slightly higher than for methanol, thus distinguishing the empty bottle from different hazardous liquids.
Meanwhile, the second spectral peak is a signal of the millimeter wave signal returning through the liquid twice, and therefore it is the first spectral peak distance position P1 plus twice the diameter of the liquid bottle at the distance position P2. Thereby, a calculation formula of the diameter d of the liquid bottle is obtained
d＝(P2-P1)/2
The diameter of the liquid bottle is calculated through the distance position of the bispectrum peak, the diameter of the liquid bottle is calculated to be 6.65 cm, the diameter is basically consistent with the actually measured diameter of the liquid bottle to be 6.5 cm, and the correctness of the scheme is verified.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (1)
1. A non-contact electromagnetic detection system for dangerous liquid is characterized in that the system is provided with a hardware system and a software system, the hardware system is a radar system with a distance measuring function, the software system is software detection comprising reflection intensity detection and reflection space spectrum peak detection, during detection, the hardware system sends millimeter wave signals, millimeter wave echo signals of an object to be detected are obtained and preprocessed, and non-contact detection is realized through detection and analysis of the software system;
the radar system comprises a signal generating circuit, a transmitting antenna, a receiving antenna, a signal receiving and demodulating circuit, a digital signal sampling and processing circuit and a related control circuit;
the receiving antenna and the transmitting antenna are both broadband and high-gain antennas;
the wave beam widths of the receiving antenna and the transmitting antenna are set to be extremely narrow, clutter caused by target reflection from the surrounding environment is reduced, and the millimeter wave detection precision and stability are improved;
the working frequency bands of the receiving antenna and the transmitting antenna are millimeter wave frequency bands, but also comprise microwave frequency bands and terahertz frequency bands;
the detection method of the non-contact electromagnetic detection system comprises the following steps:
s1, electrifying the radar system, calibrating the system, and entering a state to be detected;
s2, detecting the object to be detected by using a radar system to obtain millimeter wave echo data of the object to be detected;
s3, analyzing the data in S2 by selecting a reflection space spectrum peak detection method to obtain a detection result;
s4, analyzing the data in S2 by selecting a reflection intensity detection method to obtain a detection result;
s5 comprehensively analyzing the detection results in S3 and S4 to obtain a final conclusion;
the reflection space spectrum peak detection method is characterized in that the characteristic that the electric loss of millimeter waves in water is high is utilized, a receiving antenna only receives echoes reflected by a front wall of a liquid bottle, only a single reflection spectrum peak is generated in space, according to the characteristic that the electric loss of flammable and combustible liquid is low, the millimeter waves can penetrate through the liquid, secondary reflection is generated on the rear wall of the bottle, double reflection spectrum peaks can be generated in space, and the liquid to be detected is judged to be drinking water, dangerous liquid or an empty bottle;
the detection method of the reflection intensity is characterized in that a dangerous liquid and water are distinguished by using that the reflection signal of the water is obviously greater than that of the flammable and explosive liquid, and the dangerous liquid and an empty bottle are distinguished by using that the intensity of the secondary reflection signal of the dangerous liquid is obviously less than that of the empty bottle, so that the dangerous liquid is detected;
the container material of waiting to detect article is the liquid container of non-metallic material, and the liquid that holds in the container is safe liquid, dangerous liquid or does not hold.
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