A radioactive source quick positioning device and control system

Abstract

The application provides a radioactive source rapid positioning device and a control system, which comprise a multidirectional integrated dose detector, an unmanned platform connecting adapter, an unmanned platform and a mobile control system; the multidirectional integrated dose detector is used for monitoring dose rates in multiple directions simultaneously and determining the position of the radioactive source; the unmanned platform connecting adapter is used for safely and reliably connecting the multidirectional integrated dose detector and the unmanned platform; the unmanned platform is used for loading the probe and the connecting adapter, and different connecting adapters can be selected according to different platforms; and the mobile control system is used for controlling the movement of the unmanned platform, calculating the position of the radioactive source and controlling the movement direction, speed and distance of the unmanned platform. The application can determine the initial direction; when the initial movement direction of the unmanned platform is determined, the initial position of the radioactive source is determined through the dose rates in multiple directions, the forward direction is determined, and the detection efficiency is greatly improved.

Description

Technical Field

[0001] This invention designs a rapid radiation source location device and control system, specifically a rapid radiation source location device and control system based on a multi-directional integrated dose detector. Based on the characteristic that the radiation values ​​measured by the detection units in different directions differ, the location range of the radiation source can be determined, and a radiation source location method is proposed accordingly. The feasibility of this location method is verified by constructing a simulated radiation field using MCNP software. The results show that this method can quickly locate the radiation source within a relatively small area. Compared with the traditional carpet search method, the location efficiency is improved by more than 50%. Background Technology

[0002] Radioactive source location technology has significant application value in nuclear safety supervision, radioactive source recovery, and nuclear emergency response. Traditional radioactive source search methods mainly rely on personnel wearing protective equipment and using handheld one-way dose rate detectors (such as Geiger counters and scintillator detectors) for a comprehensive search. This method has significant drawbacks: operators are exposed to radiation, posing a high safety risk; one-way detectors can only obtain the radiation intensity at the current location and cannot directly determine the direction of the radioactive source, resulting in long search paths and low location efficiency. Experiments show that to achieve a location accuracy of 1m within a 10m × 10m area, the average search path using traditional methods is as long as 100m, taking more than 30 minutes.

[0003] In recent years, with the development of unmanned platforms (such as inspection robots and drones), automated positioning solutions using robots equipped with unidirectional detectors have emerged. While these solutions avoid the risk of human radiation exposure, their core detection technology still suffers from the following problems:

[0004] ① Lack of directional awareness: Unidirectional detectors can only obtain the total radiation at a specific point in space and cannot distinguish the direction of radiation incidence. The robot needs to repeatedly move and compare historical data using complex path planning algorithms (such as spiral search and grid traversal) to indirectly infer the location of the radiation source, essentially remaining in a "blind search" mode. Figure 1 As shown.

[0005] ② Inefficient path routing: To cover the entire area, the robot needs to traverse a large number of invalid paths. Especially in complex environments, obstacle avoidance further prolongs the search time, and the average localization efficiency is only 20%-30% higher than that of manual methods.

[0006] ③ Insufficient real-time performance: Unidirectional detection relies on multiple movements to accumulate data, resulting in weak dynamic adjustment capabilities. When the location of the radiation source changes or multiple radiation sources are present, the system response is sluggish.

[0007] While existing technologies have attempted to employ detector arrays (such as multi-probe ring arrangements), they have largely failed to achieve practical application due to the following issues:

[0008] Poor adaptability: Combining multiple independent detectors results in a large volume and weight, making it difficult to adapt to lightweight unmanned platforms, and also making it unsuitable for multiple unmanned platforms at the same time;

[0009] Significant interference: Excessive probe spacing results in low angular resolution, while insufficient spacing causes shielding interference, reducing measurement accuracy.

[0010] Data processing is complex: Existing multi-probe solutions have relatively fixed paths and require real-time calculation of radiation field distribution to determine the location of radiation sources. This makes data processing relatively complex and the algorithm has poor robustness.

[0011] To address the aforementioned problems, this invention proposes a relatively compact, multi-directional integrated dose detector for rapid localization. Through an innovative detector structure and localization algorithm, it achieves physical-level sensing of radiation direction and couples the path with the detection results, overcoming the technical limitations of unidirectional detectors. Figure 2 As shown. Summary of the Invention

[0012] This invention proposes a rapid radiation source positioning device and control system, mainly comprising four parts: a multi-directional integrated dose detector, an unmanned platform connection adapter, an unmanned platform, and an action control system.

[0013] The multi-directional integrated dose detector is used to simultaneously monitor the dose rate in multiple directions and determine the location of the radiation source.

[0014] The unmanned platform connection adapter is used to achieve a safe and reliable connection between the multi-directional integrated dose detector and the unmanned platform, and to ensure that the probe remains relatively stable during the operation of the unmanned platform.

[0015] The unmanned platform is used to load probes and connection adapters, including unmanned aerial vehicles, unmanned vehicles, unmanned ships, robots, etc., and one of them can be selected according to the mission situation. Different connection adapters can be selected according to different platforms.

[0016] The action control system is used to control the movement of the unmanned platform. Based on the real-time received probe dose rate signal, it calculates the location of the radiation source and controls the movement direction, speed, and distance of the unmanned platform.

[0017] In a rapid radioactive source positioning device and control system of the present invention, the following further components are included:

[0018] The multidirectional integrated dose detector consists of six cylindrical sodium iodide detection units. Each detection unit has a three-layer cylindrical structure, with the cylinders made of aluminum, magnesium oxide, and sodium iodide from the outside in. The structure of a single detection unit is as follows: Figure 3 As shown.

[0019] Six identical detection units, closely spaced and arranged in a circular hexagonal distribution, are designated A, B, C, D, E, and F. With the front angle defined as 0°, the centers of units A, B, and C are located at 30°, 90°, and 150° respectively in a clockwise direction. Conversely, the centers of units D, E, and F are located at -150°, -90°, and -30° respectively in a counter-clockwise direction. The gap between the six units is 1 cm, and the overall cylinder height is 6 cm. The detection units operate independently. Figure 4 As shown.

[0020] The unmanned platform connection adapter is used to connect the multi-directional integrated dose detector to the unmanned platform. Its main structure consists of an upper support plate, a lower support plate, and spring shock absorbers. The upper support plate has four detector mounting holes, each 8-10mm in diameter, for fixing the multi-directional integrated dose detector. The lower support plate has four unmanned platform mounting holes, each 12-16mm in diameter, for fixing the detector to the unmanned platform. Figure 5 As shown.

[0021] The fixing method between the spring shock absorber and the upper support plate can be flexibly selected according to the structure of the unmanned platform, the terrain conditions, and the mission requirements. The options are riveting, welding, and threaded connection. Riveting is suitable for use when the connection space is limited and the vibration during detection is large; welding is suitable for use when the terrain is complex and the reliability requirements are high; threaded connection is suitable for use when the detector needs to be replaced frequently.

[0022] When fixing, the four corners of the upper support plate should be connected to the center of the spring shock absorber, and the four corners should cover the center, with an overlap of not less than Ф10.

[0023] The unmanned platform is used to mount probes and connection adapters, including but not limited to unmanned aerial vehicles, unmanned vehicles, unmanned ships, robots, etc. The maximum walking speed of the unmanned platform is not less than 3 meters per second, and it can turn 360 degrees on the spot. It has a remote control function and can walk according to the instructions of the control system. The distance error of a single walk is not greater than 0.1 meters, and the turning error is not greater than 5 degrees.

[0024] When the selected unmanned platform is an unmanned aerial vehicle (UAV), the lower support plate is connected to the bottom of the UAV. Four fixing holes for the UAV should be reserved at the bottom. The diameter of the holes is 12-16mm and the hole spacing is 100-200mm. The holes should be matched with the holes on the lower support plate and ensure that there is no obstruction around the multi-directional detector.

[0025] When the selected unmanned platform is an unmanned vehicle, unmanned ship, or robot, the lower support plate is connected to the top of the unmanned vehicle, unmanned ship, or robot. Four fixing holes for the unmanned platform should be reserved on the top. The diameter of the holes is 12-16mm and the hole spacing is 100-200mm, which should match the hole positions of the lower support plate and ensure that there is no obstruction around the multi-directional detector.

[0026] The motion control system consists of four parts: a data acquisition module, a central processing module, a motion control module, and a communication module. These modules are cascaded and controlled via hardware interfaces and logic protocols. The system architecture is as follows: Figure 6 As shown.

[0027] ① Data acquisition module

[0028] This device receives six radiation dose rate signals in real time from a multi-directional integrated dose detector (probe). It includes a 6-channel ADC (analog-to-digital converter, sampling rate ≥1kHz) and signal conditioning circuitry (including a preamplifier and noise filter). The input port is directly connected to the signal output of the detection unit AF via a shielded cable (physical interface: aviation connector, compliant with IP67 protection standard). The output port transmits digital signals to the central processing module via an SPI bus.

[0029] ② Central Processing Module

[0030] The system executes the radiation source direction determination algorithm, path planning, and termination condition calculation. It includes an embedded processor (ARM Cortex-A53, clock speed ≥ 1.2GHz) and a storage unit (DDR4 RAM 2GB, used to cache historical coordinate data). The algorithm flow follows steps two through eight of the positioning device's control method. The input port receives signals from the data acquisition module via the SPI bus, and the output port sends motion commands to the motion control module via the UART serial port.

[0031] ③ Motion control module

[0032] The system parses motion commands to drive the unmanned platform to perform steering / movement. It includes a motion controller (STM32F407 with PID closed-loop control algorithm) and a motor drive circuit (H-bridge driver chip + current protection). The control logic is as follows: first, it receives the (angle α, step size d) command from the central processing module; then, it achieves precise 360° steering (error ≤ 5°) through encoder feedback; finally, it controls the travel distance (error ≤ 0.1m) through wheel speed pulse counting. The input port receives commands from the central processing module via a UART serial port, and the output port drives the unmanned platform's steering motor via a PWM signal, and the direction / enable signal drives the movement motor.

[0033] ④ Communication module

[0034] Enables remote data transmission from the probe to the processor and then to the unmanned platform. This includes a dual-band Wi-Fi / 4G module (SIM7600).

[0035] The protocol used is MQTT over TCP / IP. The uplink port sends probe data to the cloud monitoring terminal in real time, while the downlink port is used to receive emergency braking or manual intervention commands.

[0036] Because the six detector units in the multi-directional integrated dose detector are arranged in a cylindrical configuration and operate independently, there is some obstruction between each detector unit when the detector is placed in a radiation field for measurement. Specifically, the detector unit with the largest surface area corresponding to the incident radiation direction receives a larger number of radiation particles, while detector units further away or obstructed by other units receive a smaller number. Therefore, the number of radiation particles received by each detector unit in the six-unit NaI crystal multi-directional integrated dose detector varies within the radiation field and changes with the position of the radiation source. The angle corresponding to the unit with the larger value is the angle between the radiation source and the detector. Therefore, the incident radiation direction can be determined by the counting variation of the six detector units, thereby locating the radiation source.

[0037] If the spatial size of the radiation field is set to 10x10m 2 Establish a coordinate system with the radiation source located at (100, 0) and the unmanned equipment composed of multi-directional integrated dose detectors located at (0, 0). Figure 7 As shown.

[0038] Meanwhile, the six units A, B, C, D, E, and F of the multi-directional integrated dose detector are set to correspond to six angles, and the specific correspondence is shown in Table 1 below.

[0039] Table 1

[0040] A B C D E F 30° 90° 150° -30° -90° -150°

[0041] The radiation values ​​of the six detection units were obtained through simulation using MCNP software, as shown in Table 2.

[0042] Table 2

[0043] The code name of the detection unit A B C Detected radiation levels 1.07800E-04 1.27600E-04 1.15800E-04 The code name of the detection unit D E F Detected radiation levels 8.77000E-05 6.57000E-05 8.55000E-05

[0044] The maximum radiation value is 1.27600E-04, and the corresponding detection unit is designated B. According to Table 1, the radiation source is located to the right of the probe, within a fan-shaped area of ​​90°±30°. Figure 8 As shown.

[0045] When the multi-directional integrated dose detector detects nuclear radiation, each unit acquires a detection value and transmits it to the computer. The computer processes and analyzes the data, determining the letter number and angle corresponding to the maximum detection value among the six units, thus identifying the direction of the radiation source. The computer then sends a signal to the drive unit, controlling the unmanned equipment to turn and advance one step along the center of the sector area. For example, if unit A has the maximum detection value, the computer controls the ground-based unmanned equipment to turn 30° to the right and advance 200 centimeters. This process continues until the termination condition is met. The specific control process is as follows: Figure 9 As shown.

[0046] This invention further proposes a control method for a rapid radioactive source positioning device, comprising the following steps:

[0047] Step 1: Measure the radiation dose values ​​in 6 directions using a multi-directional integrated dose detector.

[0048] Step 2: Compare the radiation dose values ​​to obtain the maximum radiation value and its corresponding unit.

[0049] Step 3: Determine the direction of travel based on the unit number.

[0050] Step 4: The motion control system moves the unmanned platform forward by a fixed step size d.

[0051] Step 5: Calculate and record the position coordinates of the unmanned platform.

[0052] Step Six: Continue probing at the new location and repeat Step Two.

[0053] Step 7: When the cumulative number of recorded coordinates is greater than 5, the current step number is recorded as n. Obtain the coordinates from step n-4 to step n, and calculate the variance of the coordinates.

[0054] Step 8: Determine if the variance is less than the set value. If it is less than the set value, output the current coordinates as the location of the radiation source. If it is greater than the set value, repeat Step 2.

[0055] Step five further includes: calculating the position coordinates of the unmanned platform.

[0056] X n =X n-1 +d*cos(∑α)

[0057] Y n =Y n-1 +d*sin(∑α)

[0058] Among them, (X) n Y n (X) represents the current position coordinates of the unmanned platform. n-1 Y n-1() represents the coordinates of the previous position of the unmanned platform.

[0059] ∑α represents the sum of the rotation angles α of the unmanned platform at each step from the first step to the nth step.

[0060] Step seven further includes: variance σ X 2 , σ Y 2 The calculation is as follows:

[0061] σ X 2 , σ Y 2 This represents the variance of the coordinate positions in the first 5 steps.

[0062]

[0063]

[0064] Among them, (X) i Y i Let ) represent the position coordinates of the unmanned platform after moving forward i steps, and μ represent the position coordinates of the unmanned platform. X μ Y Let σ be the average value of X and Y over the last 5 steps. X 2 ,σ Y 2 That is, the corresponding variance.

[0065] Step eight further includes:

[0066] When the variance is less than the set value, i.e. σ X 2 <1.1e+4、σ Y 2 If the value is less than 6.0e+3, the source tracing process ends.

[0067] The coordinates of the radiation source (X) f Y f Estimation formula:

[0068]

[0069] The advantages and beneficial effects of this invention are as follows: 1. It can clearly define the initial direction. When determining the initial direction of travel of the unmanned platform, it is not randomly selected, but the initial orientation of the radiation source can be determined by the dose rate in multiple directions, thus clarifying the direction of travel and greatly improving the detection efficiency; 2. By utilizing the different measurement values ​​of the multi-directional integrated dose detector in different directions, the direction of travel of the unmanned platform is continuously corrected, enabling it to quickly approach the radiation source. This can significantly shorten the detection path and improve the detection efficiency. Attached Figure Description

[0070] Figure 1 This is a traditional method for locating radioactive sources.

[0071] Figure 2 This invention relates to a method for locating radioactive sources.

[0072] Figure 3 It is a structure for a single detection unit.

[0073] Figure 4 It is a multi-directional integrated dose detector structure.

[0074] Figure 5 It is an adapter structure for unmanned platforms.

[0075] Figure 6 This is a schematic diagram of the action control system architecture.

[0076] Figure 7 This is a schematic diagram showing the location of the radiation source.

[0077] Figure 8 This is the positioning principle of a multi-directional integrated dose detector.

[0078] Figure 9 Methods for controlling the movement of unmanned platforms.

[0079] Figure 10 This is a schematic diagram of the path for locating the radioactive source.

[0080] Figure 11 This is a schematic diagram illustrating an embodiment of the present invention. Detailed Implementation

[0081] To make the objectives, technical solutions, and advantages of this invention clearer and more understandable, the following description is provided in conjunction with the appendix. Figure 1-11 The present invention will be further described in detail below with reference to the technical solutions.

[0082] Taking the selection of a robot as an unmanned platform as an example, a robot dog is a type of robot with advantages such as high speed, flexible turning ability, large turning angle, high radiation resistance, ability to carry heavy detectors, strong adaptability to complex terrain, and the ability to be further developed. In this embodiment, its technical parameters are:

[0083] Standing size Approximately 1098mm × 450mm × 645mm Folding size Approximately 880mm × 460mm × 330mm weight Approximately 60kg Battery life The combined operating range is 4-6 hours. Continuous walking load >40kg Running speed >6m / s Protection level IP67 Sensing sensor configuration 3D LiDAR ×1 + Depth Camera ×2 + Optical Camera ×2

[0084] This embodiment includes a rapid radiation source positioning device and a control system, which are connected wirelessly. The multi-directional integrated dose detector and the connection adapter are connected via four M12 threads, and the connection adapter is connected to the top of the robot dog via an M14 thread, ensuring the detector is stable and secure. Figure 11 As shown.

[0085] Experimental principle:

[0086] Real-world scenario description: The multi-directional integrated dose detector receives radiation information and transmits it to the motion control system. The motion control system processes and analyzes the information to determine the approximate direction of the radiation source. Then, the motion control system sends a signal to the drive components (motor, servo motor, etc.) to control the motor or servo motor to work for a certain period of time and rotate to a predetermined angle before moving forward a certain distance.

[0087] Simulation experiment: Some insignificant factors need to be ignored; only the probe, radiation source, and air are considered, while other factors are not taken into account. The radiation values ​​detected by the probe are simulated using MCNP5 software, and then the useful information is extracted and input into a MATLAB program for analysis, drawing the operation path diagram of the radiation source localization device with multiple detection units.

[0088] Simulated two-dimensional plane, area: 10 x 10 m 2 Considering the effects of airflow and ignoring obstacles, a point-type simulation is performed. 60 A Co-type radioactive source, similar to a point source, is isotropic. Particle energy: 0.662 MeV. (Length unit precision: cm. Time unit precision: millisecond). The coordinates of the radioactive source are (800, 700). The rapid positioning device for the radioactive source has a forward stride of 200 cm and a travel speed of 1 m / s.

[0089] Experimental data:

[0090]

[0091] The location of the radioactive source is calculated, and a schematic diagram of the radioactive source location path is shown below. Figure 10 As shown.

[0092] Results Analysis and Comparison:

[0093] Using the control method proposed in this invention, a total of 13 steps are required, with a step length of 200cm and a total path length of 26m. Through data processing and analysis, it was found that after the ground-based unmanned equipment completes the 6th step, it continues to wander near the radiation source. Its wandering area is relatively small, and the radiation source is within this area, thus achieving the localization of the radiation source. Calculations using formulas show that the radiation source is located within a circular area with a radius of 1m centered at coordinates (794.641, 691.3845), and the actual coordinates of the radiation source (800, 700) are indeed within this area.

[0094] If adopted Figure 1 The traditional method shown requires a total path length of 10 x 10 = 100 m to achieve a positioning accuracy of 1 m, without considering the turning radius.

[0095] Based on the above analysis, under the condition that the positioning accuracy remains unchanged, the total path length of the method proposed in this invention is reduced by 74%, the unmanned platform movement speed remains unchanged, and the positioning efficiency is improved by 74%.

Claims

1. A rapid radioactive source positioning device, characterized in that: It includes a multi-directional integrated dose detector, an unmanned platform connection adapter, an unmanned platform, and a motion control system; among which, The multi-directional integrated dose detector is used to simultaneously monitor the dose rate in multiple directions to determine the location of the radiation source; The unmanned platform connection adapter is used to achieve a safe and reliable connection between the multi-directional integrated dose detector and the unmanned platform, and to ensure that the probe remains relatively stable during the operation of the unmanned platform. The unmanned platform is used to load probes and connection adapters, including unmanned aerial vehicles, unmanned vehicles, unmanned ships or robots, one of which is selected according to the mission, and different connection adapters are selected according to different platforms. The action control system is used to control the movement of the unmanned platform. Based on the real-time received probe dose rate signal, it calculates the location of the radiation source and controls the movement direction, speed, and distance of the unmanned platform.

2. The rapid radioactive source positioning device according to claim 1, characterized in that: The multidirectional integrated dose detector consists of six cylindrical sodium iodide detection units. Each detection unit has a three-layer cylindrical structure, with the cylinders made of aluminum, magnesium oxide, and sodium iodide from the outside to the inside.

3. The rapid radioactive source positioning device according to claim 2, characterized in that: The six detection units are identical in size and structure and are close to each other, arranged in a circular hexagonal pattern. The detection units are designated as A, B, C, D, E, and F. With the front angle as 0°, the centers of detection units A, B, and C are located at 30°, 90°, and 150° respectively in a clockwise direction. In a counterclockwise direction, the centers of detection units D, E, and F are located at -150°, -90°, and -30° respectively. The detection units operate independently of each other.

4. The rapid radioactive source positioning device according to claim 1, characterized in that: The unmanned platform connection adapter is used to connect the multi-directional integrated dose detector to the unmanned platform. Its structure consists of an upper support plate, a lower support plate, and spring shock absorbers. The upper support plate has four detector mounting holes for fixing the multi-directional integrated dose detector; the lower support plate has four unmanned platform mounting holes for fixing it to the unmanned platform. The fixing method between the spring shock absorbers and the upper support plate can be flexibly selected according to the structure of the unmanned platform, the terrain being probed, and the mission requirements. The selection method includes riveting, welding, and threaded connection. During fixing, the four corners of the upper support plate are connected to the center of the spring shock absorber, with the four corners covering the center and the overlap not less than Ф10.

5. A rapid radioactive source positioning device according to claim 1 or 4, characterized in that: The unmanned platform is used to load probes and connect adapters, including but not limited to unmanned aerial vehicles, unmanned vehicles, unmanned ships, and robots; the maximum walking speed of the unmanned platform is not less than 3 meters per second, and it can turn 360 degrees on the spot. It has a remote control function and walks according to the instructions of the control system. The distance error of a single walk is not greater than 0.1 meters, and the turning error is not greater than 5 degrees.

6. The rapid radioactive source positioning device according to claim 1, characterized in that: The motion control system consists of a data acquisition module, a central processing module, a motion control module, and a communication module. Each module achieves cascaded control through hardware interfaces and logic protocols; specifically: ① Data acquisition module It is used to receive 6 radiation dose rate signals from a multi-directional integrated dose detector in real time; it includes a 6-channel ADC and signal conditioning circuit; the input port is directly connected to the signal output terminal of the detection unit AF through a shielded cable, and the output port transmits digital signals to the central processing module through the SPI bus; ② Central Processing Module Execute the algorithm for determining the direction of the radioactive source, perform path planning, and calculate the termination conditions; It includes an embedded processor and a storage unit; the input port receives signals from the data acquisition module via the SPI bus, and the output port sends motion commands to the motion control module via the UART serial port; ③ Motion control module The system parses motion commands to drive the unmanned platform to perform steering / movement; it includes a motion controller and a motor drive circuit; the control logic is as follows: first, it receives commands from the central processing module, then achieves 360° precise steering through encoder feedback, and then controls the travel distance through wheel speed pulse counting; the input port receives commands from the central processing module through the UART serial port, and the output port drives the unmanned platform steering motor through PWM signals, and the direction / enable signal drives the travel motor. ④ Communication module It enables remote data transmission from the probe to the embedded processor to the unmanned platform; it includes a dual-band Wi-Fi / 4G module and a transparent transmission protocol: MQTT over TCP / IP; the uplink port sends probe data to the cloud monitoring terminal in real time, and the downlink port is used to receive emergency braking or manual intervention commands.

7. A control method for the rapid radioactive source positioning device according to claim 1, characterized in that: Includes the following steps: Step 1: Measure the radiation dose values ​​in 6 directions using a multi-directional integrated dose detector; Step 2: Compare the radiation dose values ​​to obtain the maximum radiation value and its corresponding unit; Step 3: Determine the direction of travel based on the unit number; Step 4: The motion control system moves the unmanned platform forward by a fixed step size d; Step 5: Calculate and record the position coordinates of the unmanned platform; Step Six: Continue probing at the new location and repeat Step Two; Step 7: When the cumulative number of recorded coordinates is greater than 5, the current step number is recorded as n. Obtain the coordinates from step n-4 to step n, and calculate the variance of the coordinates. Step 8: Determine if the variance is less than the set value. If it is less than the set value, output the current coordinates as the location of the radiation source. If it is greater than the set value, continue to repeat Step 2.

8. The control method according to claim 7, characterized in that: Step five further includes: calculating the position coordinates of the unmanned platform. Among them, (X) n ,Y n (X) represents the current position coordinates of the unmanned platform. n-1 ,Y n-1 ) represents the previous position coordinates of the unmanned platform; Σα represents the sum of the rotation angles α of the unmanned platform at each step from the first step to the nth step.

9. The control method according to claim 7, characterized in that: Step seven further includes: variance σ X 2 , σ Y 2 The calculation is as follows: σ X 2 , σ Y 2 This represents the variance of the coordinate positions in the first 5 steps. Among them, (X) i Y i Let ) represent the position coordinates of the unmanned platform after moving forward i steps, and μ represent the position coordinates of the unmanned platform. X μ Y Let σ be the average value of X and Y over the last 5 steps. X 2 , σ Y 2 That is, the corresponding variance.

10. The control method according to claim 6, characterized in that: Step eight further includes: when the variance is less than a set value, i.e. σ X 2 <1.1e+4、σ Y 2 If the value is less than 6.0e+3, the source tracing process ends. The coordinates of the radiation source (X) f Y f Estimation formula:

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