A three-dimensional positioning method and system for radioactive materials in open fields

Abstract

The present invention provides a method for three-dimensional positioning of radioactive materials in an open field, comprising: step S1, formulating a flight plan; step S2, collecting data; step S3, collecting environmental information; step S4, transmitting data back; step S5, filtering and preprocessing the data; step S6, inverting and solving for α; step S7, inverting and solving for α1; step S8, determining azimuth and elevation angles; and step S9, determining the coordinates of the radioactive material in a spherical coordinate system. The present invention also provides a three-dimensional positioning system for radioactive materials in an open field.

Description

Technical Field

[0001] The present invention belongs to the technical field of nuclear radiation detection, and in particular relates to a three-dimensional positioning method and system for radioactive materials in an open field. Background Art

[0002] With the continuous development of nuclear technology, various radioactive materials are increasingly being used in scientific research, industry, agriculture, medicine, and other fields. However, the loss of radioactive materials due to improper management and control is a common occurrence, and due to limited public awareness, this can easily cause social panic. After radioactive materials are lost, rapid and accurate location requires significant manpower and resources. Emergency search personnel operating in areas with unknown radiation levels for extended periods of time may be exposed to high doses of radiation, which can cause radiation sickness. Therefore, a method and system that can quickly and remotely locate radioactive materials in three dimensions is highly desirable.

[0003] Radioactive materials are divided into α-source, β-source, γ-source and neutron source according to the type of rays they produce. Alpha-source and β-source emit charged particles with weak penetrating ability and short range, and cannot be used for long-distance measurement and positioning. Neutron sources are relatively expensive and rarely used, and are not the focus of radioactive material positioning research. γ-source is a photon source with strong penetrating ability and is widely used in all aspects of production and life. This patent is aimed at the positioning research of γ-radioactive materials.

[0004] The scenarios for locating radioactive materials can be broadly categorized as indoors and in the open. Different factors must be considered when conducting indoor and open-field nuclear detection. Factors to consider for indoor nuclear detection include: 1. Shielding effects of building materials such as concrete, rebar, and walls, or equipment on radioactive materials, may reduce the signal strength received by some detectors. However, background radiation levels indoors are generally low. 2. Indoor spaces are relatively enclosed, which may restrict the placement and movement of detectors, impacting detection coverage and flexibility. However, temperature and humidity are relatively stable, and their effects on detection equipment can be ignored. 3. Satellite positioning signals are weakened by building materials such as concrete, rebar, and walls, making it difficult to pinpoint the detector's position. Factors to consider for open-field nuclear detection include: 1. High background radiation levels in open areas, particularly interference from cosmic rays and natural background radiation. 2. Environmental factors such as air pressure, temperature, and humidity can affect the attenuation coefficient of radiation, thereby affecting detection results. Therefore, when conducting three-dimensional localization of radioactive materials, it is important to distinguish between indoor and open-field scenarios. This patent focuses on open-field localization.

[0005] There are three main methods for locating radioactive materials in the existing technology. The first method is a positioning method based on the relationship between detector counts and position. It usually uses a single or multiple detectors to collect count and position information, and uses corresponding algorithms such as contour mapping, maximum likelihood estimation, Bayesian estimation, Markov Chain Monte Carlo (MCMC), etc. to achieve the positioning of radioactive materials. However, in order to improve detection efficiency, more measurement points are required, which is time-consuming. The closer to the radioactive material, the higher the data value, but the greater the exposure to the measurement personnel. The second method is based on gamma camera imaging positioning, which mainly achieves radioactive material positioning by focusing the gamma camera and the optical camera. However, the gamma camera is made based on the principle of pinhole imaging, and its collection field of view is small and the efficiency is low. In order to improve collection efficiency, focusing must be performed every time the scene is changed, which is inconvenient to operate. In addition, when used in open fields, strong light must be avoided, otherwise the image clarity and color saturation will be destroyed. The third method is to locate radioactive materials based on directional detectors. It can locate radioactive materials at a certain distance, reducing the exposure time of search personnel. It is a safe and efficient source search method. For example, collimators, three-crystal coupled detectors, four-unit NaI crystal directional detectors, etc. Specifically, it collects data from multiple directional detectors and locates radioactive materials through data processing. The operation is relatively cumbersome, and the system error and human error are large, which brings great trouble to subsequent data processing.

[0006] In order to quickly and effectively locate the position of radioactive materials, it is necessary to provide a three-dimensional positioning method and system for radioactive materials that can be used in open fields. Summary of the Invention

[0007] In order to solve the problems raised in the above-mentioned background technology, the present invention provides a three-dimensional positioning method and system for radioactive materials in open fields, which can search for radioactive materials in open places by carrying a detector on an aircraft, and then invert the position of the radioactive material in the coordinate system space through the detector's own position information and the relative position information between the detector and the radioactive material, the dose rate, and the environmental information. It can improve the search efficiency and positioning accuracy of nuclear radioactive materials in open fields, and provide position guidance information for guiding the rapid recovery of radioactive materials.

[0008] To achieve the above objectives, the first aspect of the present invention provides a method for three-dimensional positioning of radioactive materials in an open field, comprising:

[0009] Step S1, formulate a flight plan, divide the open field area to be searched into grids, formulate a flight plan, determine the flight altitude of the aircraft and the step grid distance, and the aircraft carrying the nuclear detector flies through each grid in turn;

[0010] Step S2, data acquisition, starts the detector and laser rangefinder, continuously detects the radiation level of the open field, records the detected dose rate, the Beidou positioning geographic coordinates of the detection point, and the flight altitude of the aircraft to generate a five-element array ,in is the three-dimensional coordinate data of the nuclear detector in the open field space, the unit is , is the flight altitude of the aircraft, in units of , The dose rate measured by the nuclear detector is that the lost radioactive material is a point source, a line source, a surface source or a volume source;

[0011] Step S3: Environmental information collection: start the temperature sensor, pressure sensor and humidity sensor to collect the temperature of the open field area to be searched. ,pressure , and humidity ;

[0012] Step S4, data backhaul, through the 5G module of the nuclear detector, the 5G modules of the temperature sensor, pressure sensor and humidity sensor, and the low-orbit satellite Internet of Things based on the 5G mobile communication technology system, the collected data is backhauled to the remote central data processing module;

[0013] Step S5, data filtering and preprocessing, the central data processing module filters the received data, deletes noise and invalid data, and establishes a relationship between environmental information and attenuation coefficient;

[0014] Step S6, inversion solution In the process of locating radioactive materials, the distance between the source and the detection device is usually far, much greater than 10 times the size of the detection device. At this time, the spatial angle of the radioactive material to the detection device is small. Therefore, it can be approximately considered that the source gamma ray reaching the surface of the detection device is a parallel beam. 、 and ,satisfy:

[0015] (1)

[0016] Step S7, inversion solution , similarly 、 and ,satisfy:

[0017] (2)

[0018] Step S8, determine the azimuth and elevation angles. Detectors A, B, and C move along the X axis, and the window surface of detector A is perpendicular to the XY horizontal plane and coincides with the XZ vertical plane. The azimuth angle is , elevation angle ;

[0019] Step S9, determine the coordinates of the radioactive material in the spherical coordinate system as , drive the laser rangefinder according to the inverse azimuth and pitch angle Deflection is performed to measure the distance between the radioactive material and the detector , that is, the coordinates of the radioactive material in the spherical coordinate system are .

[0020] As a further description of the above technical solution: the step S1 of determining the cruising altitude and the stepping grid distance of the aircraft further includes the following steps:

[0021] Step S101, estimate the effective detector distance of the detector , use the detector to obtain the average count of the natural background in the area to be searched To ensure good detection resolution, the detector is at an effective detection distance Count of radioactive materials to be searched The natural background count must be at least 3 times, without considering the attenuation of gamma rays by air, to estimate the effective detector distance ,satisfy:

[0022] (3)

[0023] Where, is the detection efficiency of the detector, is the area of ​​the detector, The activity of radioactive material is the average count of natural background in the search area, and the aircraft's flight altitude is , where the aircraft's flight altitude is Less than the detection distance ;

[0024] Step S102: Determine the effective radius of the detector's detection area on the ground. ,satisfy:

[0025] (4)

[0026] Step S103: Determine the stepping grid distance ,satisfy:

[0027] (5)

[0028] As a further description of the above technical solution: the dose rate collected in step S2 The following steps are also included:

[0029] Step S201, the dose rate collected It includes the dose rates of two adjacent fixed-angle detectors A and B at the same position in the horizontal direction. The dose rate collected by detector A is The dose rate collected by detector B is , the angle between detector A and detector B is , the angle between detector A and radioactive material in the horizontal direction of detector A and detector B is , the angle between detector B and the radioactive material is ;

[0030] Step S202, the collected dose rate It also includes the dose rates of two adjacent fixed-angle detectors A and C at the same position in the vertical direction. The dose rate collected by detector A is The dose rate collected by detector C is , the angle between detector A and detector C is , the angle between detector A and radioactive material in the vertical direction is , the angle between detector C and radioactive material is .

[0031] As a further description of the above technical solution: the step S5 of establishing the relationship between the environmental information and the attenuation coefficient further includes the following steps:

[0032] Step S501: Establishing a temperature attenuation adjustment coefficient. satisfy:

[0033] (6)

[0034] in, is the attenuation coefficient at standard temperature, pressure and humidity, is the temperature coefficient, is the actual temperature, is the standard temperature;

[0035] Step S502: Establishing a pressure decay adjustment coefficient. satisfy:

[0036] (7)

[0037] in, is the attenuation coefficient at standard temperature, pressure and humidity, is the standard pressure is the actual temperature, is the standard temperature;

[0038] Step S503: Establishing humidity attenuation adjustment coefficient and temperature attenuation adjustment coefficient satisfy:

[0039] (8)

[0040] in, is the attenuation coefficient at standard temperature, pressure and humidity, is the temperature coefficient, is the relative humidity;

[0041] Step S504: Establish a comprehensive relationship between environmental information and attenuation coefficient:

[0042] (9)

[0043] As a further description of the above technical solution: Step S6 further includes the following steps:

[0044] Step 601, determine the equation:

[0045] (10)

[0046] in, is the relative dose rate;

[0047] Step 602: Input angle The initial guess value of , the initial guess value Is the starting point of the selection, usually choose An empirical angle value is used as an initial approximation;

[0048] Step 603, determine the function, function It can be expressed as:

[0049] (11)

[0050] Step 604, determine the derivative, the derivative It can be expressed as:

[0051] (12)

[0052] Step 605, iterative calculation, through the following formula Second Perform iterative calculations:

[0053] (13)

[0054] in, For the Iteration The approximate value of is a function exist The value at is a function The derivative of The value at

[0055] Step 606: Convergence judgment, setting error tolerance ,if ,make Output , end the iterative calculation, otherwise return to step 605.

[0056] As a further description of the above technical solution: Step S7 further includes the following steps:

[0057] Step 701, determine the equation:

[0058] (14)

[0059] in, is the relative dose rate;

[0060] Step 702: Input angle The initial guess value of , the initial guess value Is the starting point of the selection, usually choose An empirical angle value is used as an initial approximation;

[0061] Step 703, determine the function, function It can be expressed as:

[0062] (15)

[0063] Step 704, determine the derivative, the derivative It can be expressed as:

[0064] (16)

[0065] Step 705, iterative calculation, through the following formula Second Perform iterative calculations:

[0066] (17)

[0067] in, For the Iteration The approximate value of is a function exist The value at is a function The derivative of The value at

[0068] Step 706: Convergence judgment, setting error tolerance ,if ,make Output , end the iterative calculation, otherwise return to step 705.

[0069] The second aspect of the present invention is a three-dimensional positioning system for radioactive materials in an open field, characterized by being used for the three-dimensional positioning method for radioactive materials in an open field as described above, comprising: an aircraft, a detector module, a laser rangefinder, a numerically controlled angle adjustment base, a 5G mobile communication module, a low-orbit satellite Internet of Things based on the 5G mobile communication technology system, and a remote central data processing module, characterized by:

[0070] The detector module also includes a radioactive ray isolation base, a detector, a preamplifier, a main amplifier, a multi-channel analyzer, a microcontroller module, and a Beidou satellite positioning module. The number of detectors is ,and The detector is arranged at the center of the circumference of the radioactive ray isolation base. The placement angle between each pair of adjacent detectors is equal and greater than 90°, and they are separated by the radioactive ray isolation base. The preamplifier, main amplifier, multi-channel analyzer, and microcontroller module are placed in the cavity of the radioactive ray isolation base. The 5G mobile communication module and Beidou satellite positioning module are placed outside the cavity of the radioactive ray isolation base.

[0071] The laser rangefinder is placed on the radioactive ray isolation base through a numerically controlled angle adjustment base and at the center of the symmetry axis between each pair of detectors;

[0072] The detector is electrically connected to a microcontroller module via a preamplifier, a main amplifier, and a multi-channel analyzer;

[0073] The laser rangefinder, the numerically controlled angle adjustment base, and the 5G mobile communication module are electrically connected to the microcontroller module;

[0074] The microcontroller module is connected to the remote data processing terminal through a 5G mobile communication module and a low-orbit satellite Internet of Things based on a 5G mobile communication technology system.

[0075] As a further description of the above technical solution: the radioactive ray isolation base includes a base, a cavity and a ring cover. The base is a part of three regular dodecagonal prisms that are perpendicular to each other in pairs, and the intersecting sides completely overlap. The horizontal and vertical directions are 7 faces connected to the sides of the dodecagonal prisms. The circumference of the bottom surface is a complete regular dodecagonal prism, and each face is a square with a side length of 12 cm. A plurality of detector mounting holes are provided on the top surface of the base. The front of the detector mounting hole is a square with a side length of 10 cm, located in the center of each side of the regular dodecagonal prism. The detector mounting hole extends along the center direction of the sphere of the radioactive ray isolation base, and the cavity is a spherical shell with a radius of 15 cm embedded in the base.

[0076] The present invention provides a three-dimensional positioning method and system for radioactive materials in open fields, which are used for remotely searching for radioactive materials in open fields. Radioactive materials in open fields are searched by carrying a detector on an aircraft, and the position of the radioactive materials in the coordinate system space is inverted by using the detector's own position information and the relative position information between the detector and the radioactive materials, the dose rate, and environmental information. This can improve the search efficiency and positioning accuracy of nuclear radioactive materials in open fields, and provide position guidance information for guiding the rapid recovery of radioactive materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0078] Figure 1 This is a flow chart of a three-dimensional positioning method for radioactive materials in an open field proposed by the present invention;

[0079] Figure 2 Schematic diagram of the relationship between the effective detection distance and the flight altitude of the aircraft according to the present invention;

[0080] Figure 3 Schematic diagram of the relationship between the effective radius and the step grid distance of the present invention;

[0081] Figure 4 This is a schematic structural diagram of a three-dimensional positioning system for radioactive materials used in an open field, as proposed by the present invention;

[0082] Figure 5 Schematic diagram of the structure of the detector module of the present invention;

[0083] Figure 6 is a cross-sectional view of the structure of the detector module of the present invention;

[0084] In the figure: 1. Aircraft, 2. Detector module, 3. Laser rangefinder, 4. CNC angle adjustment base, 5. 5G mobile communication module, 6. Low-orbit satellite Internet of Things based on 5G mobile communication technology system, 7. Remote central data processing module, 201. Radioactive ray isolation base, 202. Detector, 203. Preamplifier, 204. Main amplifier, 205. Multi-channel analyzer, 206. Microcontroller module, 207. Beidou satellite positioning module. DETAILED DESCRIPTION

[0085] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0086] Example 1

[0087] In conjunction with the instructions Figure 1 、 2 3. A first aspect of the present invention provides a method for three-dimensional positioning of radioactive materials in an open field, comprising:

[0088] Step S1, formulates a flight plan, divides the open field area to be searched into grids, formulates a flight plan, determines the flight altitude of the aircraft and the step grid distance, and the aircraft carrying the nuclear detector flies through each grid in turn, including the following steps:

[0089] Step S101, estimate the effective detector distance of the detector , use the detector to obtain the average count of the natural background in the area to be searched To ensure good detection resolution, the detector is at an effective detection distance Count of radioactive materials to be searched The natural background count must be at least 3 times, without considering the attenuation of gamma rays by air, to estimate the effective detector distance ,satisfy:

[0090] (18)

[0091] Where, is the detection efficiency of the detector, is the area of ​​the detector, The activity of radioactive material is the average count of natural background in the search area, and the aircraft's flight altitude is , where the aircraft's flight altitude is Less than the detection distance ;

[0092] Step S102: Determine the effective radius of the detector's detection area on the ground. ,satisfy:

[0093] (19)

[0094] Step S103: Determine the stepping grid distance ,satisfy:

[0095] (20)

[0096] Step S2, data acquisition, starts the detector and laser rangefinder, continuously detects the radiation level of the open field, records the detected dose rate, the Beidou positioning geographic coordinates of the detection point, and the flight altitude of the aircraft to generate a five-element array ,in is the three-dimensional coordinate data of the nuclear detector in the open field space, the unit is , is the flight altitude of the aircraft, in units of , The dose rate measured by the nuclear detector is that the lost radioactive material is a point source, a line source, a surface source or a volume source;

[0097] Step S3: Environmental information collection: start the temperature sensor, pressure sensor and humidity sensor to collect the temperature of the open field area to be searched. ,pressure , and humidity ;

[0098] Step S4, data backhaul, through the 5G module of the nuclear detector, the 5G modules of the temperature sensor, pressure sensor and humidity sensor, and the low-orbit satellite Internet of Things based on the 5G mobile communication technology system, the collected data is backhauled to the remote central data processing module;

[0099] Step S5, data filtering and preprocessing, the central data processing module filters the received data, deletes noise and invalid data, and establishes a relationship between environmental information and attenuation coefficient;

[0100] Step S6, inversion solution In the process of locating radioactive materials, the distance between the source and the detection device is usually far, much greater than 10 times the size of the detection device. At this time, the spatial angle of the radioactive material to the detection device is small. Therefore, it can be approximately considered that the source gamma ray reaching the surface of the detection device is a parallel beam. 、 and ,satisfy:

[0101] (twenty one)

[0102] Step S7, inversion solution , similarly 、 and ,satisfy:

[0103] (twenty two)

[0104] Step S8, determine the azimuth and elevation angles. Detectors A, B, and C move along the X axis, and the window surface of detector A is perpendicular to the XY horizontal plane and coincides with the XZ vertical plane. The azimuth angle is , elevation angle ;

[0105] Step S9, determine the coordinates of the radioactive material in the spherical coordinate system as , drive the laser rangefinder according to the inverse azimuth and pitch angle Deflection is performed to measure the distance between the radioactive material and the detector , that is, the coordinates of the radioactive material in the spherical coordinate system are .

[0106] Example 2

[0107] In conjunction with the instructions Figure 4 The present invention provides a three-dimensional positioning system for radioactive materials in an open field, comprising: an aircraft 1, a detector module 2, a laser rangefinder 3, a numerically controlled angle adjustment base 4, a 5G mobile communication module 5, a low-orbit satellite Internet of Things (IoT) system based on 5G mobile communication technology 6, and a remote central data processing module 7, characterized in that:

[0108] The detector module also includes a radioactive ray isolation base 201, a detector 202, a preamplifier 203, a main amplifier 204, a multi-channel analyzer 205, a microcontroller module 206, and a Beidou satellite positioning module 207. The number of the detectors 202 is The detectors are arranged at the center of the circumference of the radioactive ray isolation base. The angle between each pair of adjacent detectors is equal to 120 degrees, and they are separated by the radioactive ray isolation base 201. The preamplifier 203, the main amplifier 204, the multi-channel analyzer 205, and the microcontroller module 206 are placed in the cavity of the radioactive ray isolation base 201. The 5G mobile communication module 5 and the Beidou satellite positioning module 207 are placed outside the cavity of the radioactive ray isolation base 201.

[0109] The laser rangefinder 3 is placed on the radioactive ray isolation base 201 through a numerically controlled angle adjustment base 4 and is located at the center of the symmetry axis between each pair of detectors 202;

[0110] The detector is electrically connected to a microcontroller module 206 via a preamplifier 203, a main amplifier 204, and a multi-channel analyzer 205;

[0111] The laser rangefinder 3, the numerically controlled angle adjustment base 4, and the 5G mobile communication module 5 are electrically connected to the microcontroller module 206;

[0112] The microcontroller module 206 is connected to the remote data processing terminal 7 through the 5G mobile communication module 5 and the low-orbit satellite Internet of Things 6 based on the 5G mobile communication technology system.

[0113] In this embodiment, after the system is powered on, the aircraft 1 carries the nuclear detector 2 and flies through each grid in turn according to the flight plan. The detector module 2 collects the dose rate of the open field radioactive material, first converts the photons or electrons generated by the rays into electrical signals, and transmits them to the preamplifier 203. The preamplifier 203 amplifies the weak primary signal to ensure that the signal is not interfered with during the transmission process, and then transmits it to the main amplifier 204. The main amplifier 204 further amplifies and shapes the signal to ensure that the signal has an amplitude and shape suitable for analysis. The main amplifier 204 then transmits the signal to the multi-channel analyzer 205, and the multi-channel analyzer 205 transmits it to the microcontroller module 206 to obtain the dose rate of different detectors 2. Among them, the count rate collected by detector A is , the count rate collected by detector B is , the count collected by detector C is , detectors A and B are adjacent in the horizontal direction, and detectors A and C are adjacent in the vertical direction. The microcontroller module 206 transmits the collected dose rate information to the remote data processing terminal 7 through the 5G mobile communication module 5 and the low-orbit satellite Internet of Things 6 of the 5G mobile communication technology system. The remote data processing terminal 7 、 、 , the angle between detector A and detector B , the angle between A and detector C , calculate the azimuth , elevation angle , controls the laser rangefinder 3's rotation angle controller 4 according to the azimuth and elevation angle Rotate to measure the distance between the detector 20 and the radioactive material. The data processing terminal 7 obtains the position information of the detector module 2 through the Beidou satellite positioning module 207, and combines the azimuth , elevation ,distance Calculate the coordinates of the radioactive material.

[0114] Example 3

[0115] In conjunction with the instructions Figure 5 、 6 The present invention provides a three-dimensional positioning system for radioactive materials in an open field. The radioactive ray isolation base 201 includes a base, a cavity and a ring cover. The base is a part of three regular dodecagonal prisms that are perpendicular to each other, and the intersecting sides completely overlap. The horizontal and vertical directions are 7 faces connected to the sides of the dodecagonal prisms. The circumference of the bottom surface is a complete regular dodecagonal prism, and each face is a square with a side length of 12 cm. A plurality of detector 202 mounting holes are provided on the top surface of the base. The front of the detector 202 mounting hole is a square with a side length of 10 cm and is located in the center of each side of the regular dodecagonal prism. The detector 202 mounting hole extends along the center of the sphere of the radioactive ray isolation base 201. The cavity is a spherical shell with a radius of 15 cm embedded in the base.

[0116] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0117] Those skilled in the art will clearly understand that for the sake of convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the system can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into a single processing unit, or each unit can exist physically separately, or two or more units can be integrated into a single unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the purpose of distinguishing them from each other and are not intended to limit the scope of protection of this application. The specific working processes of the units and modules in the above-mentioned wireless terminal can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0118] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0119] In the embodiments provided by the present invention, it should be understood that the disclosed systems / terminal devices and methods can be implemented in other ways. For example, the system / terminal device embodiments described above are merely illustrative. For example, the division of the modules or units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the system or unit can be electrical, mechanical or other forms.

[0120] The units described as separate components may or may not be physically separate, and the components described as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0121] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A three-dimensional positioning method for radioactive materials in an open field, characterized in that: include: Step S1: Formulate a flight plan, divide the open field area to be searched into grids, determine the flight altitude of the aircraft and the stepping grid distance, and the aircraft carrying the nuclear detector flies through each grid in turn; Step S2, data acquisition, starts the detector and laser rangefinder, continuously detects the radiation level of the open field, records the detected dose rate, the Beidou positioning geographic coordinates of the detection point, and the flight altitude of the aircraft to generate a five-element array ,in is the three-dimensional coordinate data of the nuclear detector in the open field space, the unit is , is the flight altitude of the aircraft, in units of , The dose rate measured by the nuclear detector is that the lost radioactive material is a point source, a line source, a surface source or a volume source; Step S3: Environmental information collection: start the temperature sensor, pressure sensor and humidity sensor to collect the temperature of the open field area to be searched. ,pressure , and humidity ; Step S4, data backhaul, through the 5G module of the nuclear detector, the 5G modules of the temperature sensor, pressure sensor and humidity sensor, and the low-orbit satellite Internet of Things based on the 5G mobile communication technology system, the collected data is backhauled to the remote central data processing module; Step S5, data filtering and preprocessing, the central data processing module filters the received data, deletes noise and invalid data, and establishes a relationship between environmental information and attenuation coefficient; Step S6, inversion solution , 、 and ,satisfy: ; Step S7, inversion solution , 、 and ,satisfy: ; Step S8, determine the azimuth and elevation angles. Detectors A, B, and C move along the X axis, and the window surface of detector A is perpendicular to the XY horizontal plane and coincides with the XZ vertical plane. The azimuth angle is , elevation angle ; Step S9, determine the coordinates of the radioactive material in the spherical coordinate system as , drive the laser rangefinder according to the inverse azimuth and pitch angle Deflection is performed to measure the distance between the radioactive material and the detector , that is, the coordinates of the radioactive material in the spherical coordinate system are .

2. A three-dimensional positioning method for radioactive materials in an open field according to claim 1, characterized in that: The step S1 determines the cruising altitude and stepping grid distance of the aircraft, and further includes the following steps: Step S101, estimate the effective detector distance of the detector , use the detector to obtain the average count of the natural background in the area to be searched , estimate the effective detector distance ,satisfy: , where is the detection efficiency of the detector, is the area of ​​the detector, The activity of radioactive material is the average count of natural background in the search area, and the aircraft's flight altitude is , where the aircraft's flight altitude is Less than the detection distance ; Step S102: Determine the effective radius of the detector's detection area on the ground. ,satisfy: ; Step S103: Determine the stepping grid distance ,satisfy: .

3. The method for three-dimensional positioning of radioactive materials in an open field according to claim 1, characterized in that: The dose rate collected in step S2 The following steps are also included: Step S201, the dose rate collected It includes the dose rates of two adjacent fixed-angle detectors A and B at the same position in the horizontal direction. The dose rate collected by detector A is The dose rate collected by detector B is , the angle between detector A and detector B is , the angle between detector A and radioactive material in the horizontal direction of detector A and detector B is , the angle between detector B and the radioactive material is ; Step S202, the collected dose rate It also includes the dose rates of two adjacent fixed-angle detectors A and C at the same position in the vertical direction. The dose rate collected by detector A is The dose rate collected by detector C is , the angle between detector A and detector C is , the angle between detector A and radioactive material in the vertical direction is , the angle between detector C and radioactive material is .

4. The method for three-dimensional positioning of radioactive materials in an open field according to claim 1, characterized in that: The step S5 of establishing the relationship between the environmental information and the attenuation coefficient further includes the following steps: Step S501: Establishing a temperature attenuation adjustment coefficient. satisfy: ,in, is the attenuation coefficient at standard temperature, pressure and humidity, is the temperature coefficient, is the actual temperature, is the standard temperature; Step S502: Establishing a pressure decay adjustment coefficient. satisfy: ,in, is the attenuation coefficient at standard temperature, pressure and humidity, is the standard pressure is the actual temperature, is the standard temperature; Step S503: Establishing humidity attenuation adjustment coefficient and temperature attenuation adjustment coefficient satisfy: ,in, is the attenuation coefficient at standard temperature, pressure and humidity, is the temperature coefficient, is the relative humidity; Step S504: Establish a comprehensive relationship between environmental information and attenuation coefficient: 。 5. The method for three-dimensional positioning of radioactive materials in an open field according to claim 1, characterized in that: The step S6 further comprises the following steps: Step 601, determine the equation: ,in, is the relative dose rate; Step 602: Input angle The initial guess value of , the initial guess value Is the starting point of choice, choice An empirical angle value is used as an initial approximation; Step 603, determine the function, function It can be expressed as: ; Step 604, determine the derivative, the derivative It can be expressed as: ； Step 605, iterative calculation, through the following formula Second Perform iterative calculations: ,in, For the Iteration The approximate value of is a function exist The value at is a function The derivative of The value at Step 606: Convergence judgment, setting error tolerance ,if ,make Output , end the iterative calculation, otherwise return to step 605.

6. The method for three-dimensional positioning of radioactive materials in an open field according to claim 1, characterized in that: The step S7 further comprises the following steps: Step 701, determine the equation: ,in, is the relative dose rate; Step 702: Input angle The initial guess value of , the initial guess value Is the starting point of choice, choice An empirical angle value is used as an initial approximation; Step 703, determine the function, function It can be expressed as: ; Step 704, determine the derivative, the derivative It can be expressed as: ； Step 705, iterative calculation, through the following formula Second Perform iterative calculations: ,in, For the Iteration The approximate value of is a function exist The value at is a function The derivative of The value at Step 706: Convergence judgment, setting error tolerance ,if ,make Output , end the iterative calculation, otherwise return to step 705.

7. A three-dimensional positioning system for radioactive materials in an open field, used in the three-dimensional positioning method for radioactive materials in an open field according to any one of claims 1 to 6, comprising: Aircraft, detector module, laser rangefinder, numerical control angle adjustment base, 5G mobile communication module, low-orbit satellite Internet of Things based on 5G mobile communication technology system, remote central data processing module, characterized in that: the detector module also includes a radioactive ray isolation base, a detector, a preamplifier, a main amplifier, a multi-channel analyzer, a microcontroller module, and a Beidou satellite positioning module, the number of detectors is n, and n ≥ 5, the detector is set at the center of the circumference of the radioactive ray isolation base, the placement angle between each pair of adjacent detectors is equal and greater than 90°, and they are separated by the radioactive ray isolation base, the preamplifier, the main amplifier, the multi-channel analyzer, the microcontroller module, and the Beidou satellite positioning module. The device module is placed in the cavity of the radioactive ray isolation base, and the 5G mobile communication module and the Beidou satellite positioning module are placed outside the cavity of the radioactive ray isolation base; the laser rangefinder is placed on the radioactive ray isolation base through a numerically controlled angle adjustment base and at the center of the symmetry axis between each pair of detectors; the detector is electrically connected to the microcontroller module through a preamplifier, a main amplifier, and a multi-channel analyzer; the laser rangefinder, the numerically controlled angle adjustment base, and the 5G mobile communication module are electrically connected to the microcontroller module; the microcontroller module is connected to a remote data processing terminal through the 5G mobile communication module and a low-orbit satellite Internet of Things based on the 5G mobile communication technology system.

8. The three-dimensional positioning system for radioactive materials in an open field according to claim 7, characterized in that: The radioactive ray isolation base includes a base, a cavity and a ring cover. The base is part of three regular dodecagonal prisms that are perpendicular to each other in pairs, and the intersecting sides completely overlap. The horizontal and vertical directions are 7 faces connected to the sides of the dodecagonal prisms. The circumference of the bottom surface is a complete regular dodecagonal prism, and each face is a square with a side length of 12 cm. Multiple detector mounting holes are provided on the top surface of the base. The front of the detector mounting hole is a square with a side length of 10 cm and is located in the center of each side of the regular dodecagonal prism. The detector mounting hole extends along the center of the sphere of the radioactive ray isolation base. The cavity is a spherical shell with a radius of 15 cm embedded in the base.

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