A Target Conflict Detection Method for Low-Altitude High-Density Surveillance Based on Grid Coding

Abstract

The present invention discloses a low-altitude high-density surveillance target conflict detection method based on grid coding, including setting horizontal and vertical safety distances and surveillance target disappearance thresholds; selecting any point in the surveillance area as the origin, establishing a three-dimensional coordinate system and rasterizing the surveillance area; assigning a unique number to each grid and storing it in a dictionary table, and creating a surveillance target queue sorted by timestamp; calculating the grid number of the surveillance target according to its current position, and updating or adding the surveillance target position information in the dictionary table, while recording the timestamp and adding the information to the surveillance target queue; continuously monitoring the surveillance target queue, removing surveillance targets that exceed the disappearance threshold, and updating the dictionary table; judging whether a conflict occurs by checking whether there are other surveillance targets in the grid where the surveillance target is located and its neighboring 26 grids, and triggering an alarm if so. The method of the present invention can dynamically and quickly judge whether a large number of surveillance targets have a collision risk.

Description

Technical Field

[0001] The invention belongs to the field of civil aviation traffic management, and in particular relates to a low-altitude high-density surveillance target conflict detection method based on raster coding. Background Art

[0002] With the rapid development of low-altitude UAV technology, UAVs have been widely used in agriculture, logistics, monitoring, entertainment and other fields. However, the large-scale deployment of UAVs has also brought about the problem of track conflicts, especially in low-altitude areas, where the space is dense and the routes are intertwined, and the risk of collision between UAVs has increased significantly. Therefore, effective UAV track conflict detection technology has become the key to ensuring flight safety.

[0003] In the prior art, UAV track conflict detection mainly relies on directly calculating the distance between two UAVs to determine whether the two are in a potential conflict state. Specifically, by acquiring the position information of the UAVs in real time, the relative distance between the UAVs is calculated. When the relative distance is less than the preset safety threshold, it is determined that there is a conflict. This method is concise and easy to implement in theory, but it has great limitations in practical applications. As the number of UAVs increases, the amount of calculation of the distance between two UAVs increases exponentially, resulting in huge consumption of computing resources and long computing time, making it difficult to achieve real-time and efficient conflict detection. Therefore, it is necessary to study a more efficient UAV conflict detection method. Summary of the invention

[0004] In view of the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a low-altitude high-density surveillance target conflict detection method based on grid coding, grid modeling is performed for all low-altitude airspaces in the surveillance area, the airspace grid is divided by vertical intervals and horizontal intervals, and then according to the real-time position of the surveillance target, the decision-making judgment of the surveillance target track conflict is made to ensure that the surveillance target can achieve collision avoidance in the surveillance area. The present invention optimizes the conflict detection calculation method, can simultaneously process high-density surveillance target data, reduce the number of calculations, reduce the calculation time, and can improve the safe operation level of the surveillance target.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a low-altitude high-density surveillance target conflict detection method based on grid coding, and the steps are as follows:

[0007] Step S1: setting the horizontal safety distance, vertical safety distance and monitoring target track disappearance threshold between monitoring targets;

[0008] Step S2: Select any point in the monitoring area as the origin of the coordinate system, construct a three-dimensional space coordinate system based on the vertical safety distance and the horizontal safety distance, and rasterize the entire monitoring area;

[0009] Step S3: Create a monitoring area grid dictionary table, assign a unique number to each rasterized spatial position, and store it in the monitoring area grid dictionary table;

[0010] Step S4: creating a monitoring target queue, and sorting the monitoring targets in the queue according to the acquired monitoring target trajectory timestamps;

[0011] Step S5: Based on the location information of the current monitoring target, the grid number of the current monitoring target is calculated and determined, the grid of the current monitoring target is located in the monitoring area grid dictionary table by the grid number, the current monitoring target is classified into the corresponding grid, the location information of the current monitoring target is added or updated in the monitoring area grid dictionary table, and the current timestamp of the current monitoring target is recorded, and the location information of the current monitoring target is sent to the monitoring target queue;

[0012] Step S6: real-time monitoring of the monitoring target queue is performed, and the monitoring target position information exceeding the monitoring target disappearance threshold in the monitoring target queue is obtained and deleted regularly, and the monitoring target information in the monitoring area grid dictionary table is deleted according to the monitoring target position information;

[0013] Step S7: retrieve the grid where the monitoring target is located and its 26 surrounding adjacent grids from the monitoring area grid dictionary table by grid number, and determine whether there are other monitoring targets in the grid where the current monitoring target is located and its 26 surrounding adjacent grids. If so, it is considered that there is a security risk for the current monitoring target and a conflict alarm is issued; if not, the current monitoring target is in a safe state.

[0014] Furthermore, the step S1 specifically includes:

[0015] The horizontal safety distance h between surveillance targets is set to define the minimum interval that a surveillance target should maintain with other surveillance targets in the horizontal direction; the vertical safety distance k between surveillance targets is set to control the safety range of the surveillance target in the vertical direction; the surveillance target trajectory disappearance threshold l is set to determine whether the surveillance target has left effective surveillance or the trajectory has been interrupted.

[0016] Furthermore, the step S2 specifically includes:

[0017] Select any point in the monitoring area B as the origin of the coordinate system O, marked as , establish a spatial rectangular coordinate system with point O, use the horizontal safety distance h as the step length of the x-axis and y-axis of the spatial coordinate system, and use the vertical safety distance k as the step length of the z-axis of the spatial rectangular coordinate system to obtain the rasterized monitoring area as follows:

[0018] ;

[0019] Among them, n represents the total number of vertices rasterized along the x-axis direction with the horizontal safety distance as the step length; i represents the total number of vertices rasterized along the y-axis direction with the horizontal safety distance as the step length; u represents the total number of vertices rasterized along the z-axis direction with the vertical safety distance as the step length; B0 represents all grids with a height of 0, B1 represents all grids with a height of 1, and B u Represents all grids with height u;

[0020] In the spatial rectangular coordinate system, according to the numbered coordinates B (q, w, e) of the numbered areas from left to right and from bottom to top; wherein q represents the serial number of the grid in the x-axis direction in the three-dimensional spatial coordinates, w represents the serial number of the grid in the y-axis direction in the three-dimensional spatial coordinates; and e represents the serial number of the grid in the z-axis direction in the three-dimensional spatial coordinates; the division and numbering of the monitoring area grids are completed to obtain multiple monitoring area grids.

[0021] Furthermore, the step S3 specifically includes:

[0022] Create a monitoring area grid dictionary table P, the key of which is the number of the monitoring area grid, and the value is the set of all monitoring targets contained in the monitoring area grid; the monitoring area grid coordinates are B(q,w,e), assigned with a number qwe, and mapped to P(qwe) in the dictionary table P; each monitoring target set is represented as a set, which contains the location information of multiple monitoring targets, and each monitoring target includes the following attributes: longitude Lon, latitude Lat, height Height, and unique identification number ID of the monitoring target;

[0023] The unique number of the monitoring area is used to determine whether the monitoring area grid to be queried is in the monitoring area grid dictionary table. If so, the relevant information of the grid is returned or updated; if not, a new grid entry is added to the monitoring area grid dictionary table and an empty monitoring area grid is initialized.

[0024] Furthermore, the step S4 specifically includes:

[0025] Create a monitoring target queue S, which uses the monitoring target unique identification number ID as the key and the current position data of the monitoring target as the value; when the monitoring target queue receives new monitoring target position data, the queue is reordered according to the timestamp of the acquired data to ensure that the smallest timestamp in the queue is at the head of the queue.

[0026] Furthermore, the step S5 specifically includes:

[0027] The location information of the current monitoring target is obtained from the sensor or data source of the monitoring system. The set horizontal safety interval and vertical safety interval are used as the grid division standard. The grid index of the monitoring target in the horizontal direction is obtained by dividing the difference between the latitude and longitude coordinates of the monitoring target and the coordinates of the starting point of the monitoring area by the horizontal safety interval. The grid index of the monitoring target in the vertical direction is obtained by dividing the difference between the height of the monitoring target and the height of the starting point of the monitoring area by the vertical safety interval. The three-dimensional grid number where the monitoring target is located is calculated by combining the grid indexes in the horizontal and vertical directions.

[0028] According to the three-dimensional grid number obtained above, the corresponding grid is found in the monitoring area grid dictionary table, and the location information of the current monitoring target in the monitoring area grid dictionary table is updated. If the current monitoring target is not stored in the monitoring area grid dictionary table, a new record is created;

[0029] The current timestamp of the current monitoring target is used as the timestamp, and the location data and timestamp of the current monitoring target are sent to the monitoring target queue S according to the unique identification number ID of the monitoring target.

[0030] Furthermore, the step S6 specifically includes:

[0031] Real-time monitoring of the surveillance target queue S. When the timestamp of the surveillance target at the head of the queue exceeds the surveillance target trajectory disappearance threshold, it is considered that the surveillance target has lost effective tracking or the trajectory has been interrupted. The surveillance target location information is obtained and deleted from the queue, and the location information of the surveillance target is deleted from the surveillance area raster dictionary table based on the obtained location information.

[0032] Furthermore, the step S7 specifically includes:

[0033] The number qwe of the grid where the current monitoring target is located is obtained through the location information of the monitoring target. The grid where the monitoring target is located is obtained from the monitoring area grid dictionary table, and the adjacent grid set R around the monitoring target is obtained through the current grid number qwe. The specific process is as follows:

[0034] ;

[0035] Obtain all surveillance targets in the surveillance area around the surveillance target through the grid set R;

[0036] If it is calculated that there are no other surveillance targets in the surveillance area grid where the current surveillance target is located and its adjacent 26 surveillance area grids , the current monitoring target is in a safe state;

[0037] If it is calculated that there are other surveillance targets in the surveillance area grid where the current surveillance target is located and its adjacent 26 surveillance area grids , then there is a security risk in the current monitoring target and a conflict alarm is issued.

[0038] Beneficial effects of the present invention:

[0039] The present invention rasterizes the entire monitoring area to achieve digitalization of the monitoring area, can monitor a large number of high-density monitoring targets at the same time, omits the calculation process between monitoring object points, directly performs conflict detection on the monitoring objects in the form of spatial views, avoids a large number of calculation and judgment processes, and improves computing efficiency; in addition, the present invention further accelerates the search speed and saves memory resources by introducing a monitoring area dictionary table; the present invention can dynamically delete invalid track points through the application of the monitoring area queue, thereby ensuring the accuracy and real-time nature of the monitoring data. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a flow chart of the method of the present invention;

[0041] Figure 2 It is a schematic diagram of the vertices of the monitoring area in the present invention;

[0042] Figure 3 It is a rasterized schematic diagram of the monitoring area in the present invention;

[0043] Figure 4 It is a schematic diagram of the conflict detection principle in the present invention;

[0044] Figure 5 This is a flow chart of monitoring target conflict detection in the present invention. DETAILED DESCRIPTION

[0045] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments and drawings. The contents mentioned in the implementation modes are not intended to limit the present invention.

[0046] Reference Figures 1 to 5 As shown, a low-altitude high-density surveillance target conflict detection method based on grid coding of the present invention comprises the following steps:

[0047] Step S1: setting the horizontal safety distance, vertical safety distance and monitoring target track disappearance threshold between monitoring targets;

[0048] The horizontal safety distance h between surveillance targets is set to define the minimum interval that a surveillance target should maintain with other surveillance targets in the horizontal direction; the vertical safety distance k between surveillance targets is set to control the safety range of the surveillance target in the vertical direction; the surveillance target trajectory disappearance threshold l is set to determine whether the surveillance target has left effective surveillance or the trajectory has been interrupted.

[0049] Step S2: Select any point in the monitoring area as the origin of the coordinate system, construct a three-dimensional space coordinate system based on the vertical safety distance and the horizontal safety distance, and rasterize the entire monitoring area;

[0050] Select any point in the monitoring area B as the origin of the coordinate system O, marked as , establish a spatial rectangular coordinate system with point O, use the horizontal safety distance h as the step length of the x-axis and y-axis of the spatial coordinate system, and use the vertical safety distance k as the step length of the z-axis of the spatial rectangular coordinate system to obtain the rasterized monitoring area as follows:

[0051] ;

[0052] Among them, n represents the total number of vertices rasterized along the x-axis direction with the horizontal safety distance as the step length; i represents the total number of vertices rasterized along the y-axis direction with the horizontal safety distance as the step length; u represents the total number of vertices rasterized along the z-axis direction with the vertical safety distance as the step length; B0 represents all grids with a height of 0, B1 represents all grids with a height of 1, and B u Represents all grids with height u;

[0053] In the spatial rectangular coordinate system, according to the numbered coordinates B (q, w, e) of the numbered areas from left to right and from bottom to top; wherein q represents the serial number of the grid in the x-axis direction in the three-dimensional spatial coordinates, w represents the serial number of the grid in the y-axis direction in the three-dimensional spatial coordinates; and e represents the serial number of the grid in the z-axis direction in the three-dimensional spatial coordinates; the division and numbering of the monitoring area grids are completed to obtain multiple monitoring area grids.

[0054] Step S3: Create a monitoring area grid dictionary table, assign a unique number to each rasterized spatial position, and store it in the monitoring area grid dictionary table;

[0055] Create a monitoring area grid dictionary table P, the key of which is the number of the monitoring area grid, and the value is the set of all monitoring targets contained in the monitoring area grid; the monitoring area grid coordinates are B(q,w,e), assigned with a number qwe, and mapped to P(qwe) in the dictionary table P; each monitoring target set is represented as a set, which contains the location information of multiple monitoring targets, and each monitoring target includes the following attributes: longitude Lon, latitude Lat, height Height, and unique identification number ID of the monitoring target;

[0056] The unique number of the monitoring area is used to determine whether the monitoring area grid to be queried is in the monitoring area grid dictionary table. If so, the relevant information of the grid is returned or updated; if not, a new grid entry is added to the monitoring area grid dictionary table and an empty monitoring area grid is initialized.

[0057] Step S4: creating a monitoring target queue, and sorting the monitoring targets in the queue according to the acquired monitoring target trajectory timestamps;

[0058] Create a monitoring target queue S, which uses the monitoring target unique identification number ID as the key and the current position data of the monitoring target as the value; when the monitoring target queue receives new monitoring target position data, the queue is reordered according to the timestamp of the acquired data to ensure that the smallest timestamp in the queue is at the head of the queue.

[0059] Step S5: Based on the location information of the current monitoring target, the grid number of the current monitoring target is calculated and determined, the grid of the current monitoring target is located in the monitoring area grid dictionary table by the grid number, the current monitoring target is classified into the corresponding grid, the location information of the current monitoring target is added or updated in the monitoring area grid dictionary table, and the current timestamp of the current monitoring target is recorded, and the location information of the current monitoring target is sent to the monitoring target queue;

[0060] The location information of the current monitoring target is obtained from the sensor or data source of the monitoring system. The set horizontal safety interval and vertical safety interval are used as the grid division standard. The grid index of the monitoring target in the horizontal direction is obtained by dividing the difference between the latitude and longitude coordinates of the monitoring target and the coordinates of the starting point of the monitoring area by the horizontal safety interval. The grid index of the monitoring target in the vertical direction is obtained by dividing the difference between the height of the monitoring target and the height of the starting point of the monitoring area by the vertical safety interval. The three-dimensional grid number where the monitoring target is located is calculated by combining the grid indexes in the horizontal and vertical directions.

[0061] According to the three-dimensional grid number obtained above, the corresponding grid is found in the monitoring area grid dictionary table, and the location information of the current monitoring target in the monitoring area grid dictionary table is updated. If the current monitoring target is not stored in the monitoring area grid dictionary table, a new record is created;

[0062] The current timestamp (current system time) of the current monitoring target is used as the timestamp, and the location data and timestamp of the current monitoring target are sent to the monitoring target queue S according to the unique identification number ID of the monitoring target.

[0063] Step S6: real-time monitoring of the monitoring target queue is performed, and the monitoring target position information exceeding the monitoring target disappearance threshold in the monitoring target queue is obtained and deleted regularly, and the monitoring target information in the monitoring area grid dictionary table is deleted according to the monitoring target position information;

[0064] Real-time monitoring of the surveillance target queue S. When the timestamp of the surveillance target at the head of the queue exceeds the surveillance target trajectory disappearance threshold, it is considered that the surveillance target has lost effective tracking or the trajectory has been interrupted. The surveillance target location information is obtained and deleted from the queue, and the location information of the surveillance target is deleted from the surveillance area raster dictionary table based on the obtained location information.

[0065] Step S7: retrieve the grid where the monitoring target is located and its 26 surrounding adjacent grids from the monitoring area grid dictionary table by grid number, and determine whether there are other monitoring targets in the grid where the current monitoring target is located and its 26 surrounding adjacent grids. If so, it is considered that the current monitoring target has a security risk and a conflict alarm is issued; if not, the current monitoring target is in a safe state;

[0066] The number qwe of the grid where the current monitoring target is located is obtained through the location information of the monitoring target. The grid where the monitoring target is located is obtained from the monitoring area grid dictionary table, and the adjacent grid set R around the monitoring target is obtained through the current grid number qwe. The specific process is as follows:

[0067] ;

[0068] Obtain all surveillance targets in the surveillance area around the surveillance target through the grid set R;

[0069] If it is calculated that there are no other surveillance targets in the surveillance area grid where the current surveillance target is located and its adjacent 26 surveillance area grids , the current monitoring target is in a safe state;

[0070] If it is calculated that there are other surveillance targets in the surveillance area grid where the current surveillance target is located and its adjacent 26 surveillance area grids , then there is a security risk in the current monitoring target and a conflict alarm is issued.

[0071] The present invention has many specific application paths. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements can be made without departing from the principle of the present invention. These improvements should also be regarded as the protection scope of the present invention.

Claims

1. A low-altitude high-density surveillance target conflict detection method based on grid coding, characterized in that: Here are the steps: Step S1: setting the horizontal safety distance, vertical safety distance and monitoring target track disappearance threshold between monitoring targets; Step S2: Select any point in the monitoring area as the origin of the coordinate system, construct a three-dimensional space coordinate system based on the vertical safety distance and the horizontal safety distance, and rasterize the entire monitoring area; Step S3: Create a monitoring area grid dictionary table, assign a unique number to each rasterized spatial position, and store it in the monitoring area grid dictionary table; Step S4: creating a monitoring target queue, and sorting the monitoring targets in the queue according to the acquired monitoring target trajectory timestamps; Step S5: Based on the location information of the current monitoring target, the grid number of the current monitoring target is calculated and determined, the grid of the current monitoring target is located in the monitoring area grid dictionary table by the grid number, the current monitoring target is classified into the corresponding grid, the location information of the current monitoring target is added or updated in the monitoring area grid dictionary table, and the current timestamp of the current monitoring target is recorded, and the location information of the current monitoring target is sent to the monitoring target queue; Step S6: real-time monitoring of the monitoring target queue is performed, and the monitoring target position information exceeding the monitoring target disappearance threshold in the monitoring target queue is obtained and deleted regularly, and the monitoring target information in the monitoring area grid dictionary table is deleted according to the monitoring target position information; Step S7: retrieve the grid where the monitoring target is located and its 26 surrounding adjacent grids from the monitoring area grid dictionary table by grid number, and determine whether there are other monitoring targets in the grid where the current monitoring target is located and its 26 surrounding adjacent grids. If so, it is considered that there is a security risk for the current monitoring target and a conflict alarm is issued; if not, the current monitoring target is in a safe state.

2. The low-altitude high-density surveillance target conflict detection method based on grid coding according to claim 1 is characterized in that: The step S1 specifically includes: The horizontal safety distance h between surveillance targets is set to define the minimum interval that a surveillance target should maintain with other surveillance targets in the horizontal direction; the vertical safety distance k between surveillance targets is set to control the safety range of the surveillance target in the vertical direction; the surveillance target trajectory disappearance threshold l is set to determine whether the surveillance target has left effective surveillance or the trajectory has been interrupted.

3. The low-altitude high-density surveillance target conflict detection method based on grid coding according to claim 1 is characterized in that: The step S2 specifically includes: Select any point in the monitoring area B as the origin of the coordinate system O, marked as , establish a spatial rectangular coordinate system with point O, use the horizontal safety distance h as the step length of the x-axis and y-axis of the spatial coordinate system, and use the vertical safety distance k as the step length of the z-axis of the spatial rectangular coordinate system to obtain the rasterized monitoring area as follows: ； Among them, n represents the total number of vertices rasterized along the x-axis direction with the horizontal safety distance as the step length; i represents the total number of vertices rasterized along the y-axis direction with the horizontal safety distance as the step length; u represents the total number of vertices rasterized along the z-axis direction with the vertical safety distance as the step length; B0 represents all grids with a height of 0, B1 represents all grids with a height of 1, and B u Represents all grids with height u; In the spatial rectangular coordinate system, according to the numbered coordinates B (q, w, e) of the numbered areas from left to right and from bottom to top; wherein q represents the serial number of the grid in the x-axis direction in the three-dimensional spatial coordinates, w represents the serial number of the grid in the y-axis direction in the three-dimensional spatial coordinates; and e represents the serial number of the grid in the z-axis direction in the three-dimensional spatial coordinates; the division and numbering of the monitoring area grids are completed to obtain multiple monitoring area grids.

4. The method for detecting conflict between low-altitude and high-density surveillance targets based on grid coding according to claim 1, characterized in that: The step S3 specifically includes: Create a monitoring area grid dictionary table P, the key of which is the number of the monitoring area grid, and the value is the set of all monitoring targets contained in the monitoring area grid; the monitoring area grid coordinates are B(q,w,e), assigned with a number qwe, and mapped to P(qwe) in the dictionary table P; each monitoring target set is represented as a set, which contains the location information of multiple monitoring targets, and each monitoring target includes the following attributes: longitude Lon, latitude Lat, height Height, and unique identification number ID of the monitoring target; The unique number of the monitoring area is used to determine whether the monitoring area grid to be queried is in the monitoring area grid dictionary table. If so, the relevant information of the grid is returned or updated; if not, a new grid entry is added to the monitoring area grid dictionary table and an empty monitoring area grid is initialized.

5. The low-altitude high-density surveillance target conflict detection method based on grid coding according to claim 1 is characterized in that: The step S4 specifically includes: Create a monitoring target queue S, which uses the unique identification number ID of the monitoring target as the key and the current position data of the monitoring target as the value; when the monitoring target queue receives new monitoring target position data, the queue is reordered according to the timestamp of the acquired data to ensure that the smallest timestamp in the queue is at the head of the queue.

6. The method for low-altitude high-density surveillance target conflict detection based on grid coding according to claim 1, characterized in that: The step S5 specifically includes: The location information of the current monitoring target is obtained from the sensor or data source of the monitoring system. The set horizontal safety interval and vertical safety interval are used as the grid division standard. The grid index of the monitoring target in the horizontal direction is obtained by dividing the difference between the latitude and longitude coordinates of the monitoring target and the coordinates of the starting point of the monitoring area by the horizontal safety interval. The grid index of the monitoring target in the vertical direction is obtained by dividing the difference between the height of the monitoring target and the height of the starting point of the monitoring area by the vertical safety interval. The three-dimensional grid number where the monitoring target is located is calculated by combining the grid indexes in the horizontal and vertical directions. According to the three-dimensional grid number obtained above, the corresponding grid is found in the monitoring area grid dictionary table, and the location information of the current monitoring target in the monitoring area grid dictionary table is updated. If the current monitoring target is not stored in the monitoring area grid dictionary table, a new record is created; The current timestamp of the current monitoring target is used as the timestamp, and the position data and timestamp of the current monitoring target are sent to the monitoring target queue S according to the unique identification number ID of the monitoring target.

7. The method for low-altitude high-density surveillance target conflict detection based on grid coding according to claim 1, characterized in that: The step S6 specifically includes: Real-time monitoring of the surveillance target queue S. When the timestamp of the surveillance target at the head of the queue exceeds the surveillance target trajectory disappearance threshold, it is considered that the surveillance target has lost effective tracking or the trajectory has been interrupted. The surveillance target location information is obtained and deleted from the queue, and the location information of the surveillance target is deleted from the surveillance area raster dictionary table based on the obtained location information.

8. The low-altitude high-density surveillance target conflict detection method based on grid coding according to claim 1 is characterized in that: The step S7 specifically includes: The number qwe of the grid where the current monitoring target is located is obtained through the location information of the monitoring target. The grid where the monitoring target is located is obtained from the monitoring area grid dictionary table, and the adjacent grid set R around the monitoring target is obtained through the current grid number qwe. The specific process is as follows: ； Obtain all surveillance targets in the surveillance area around the surveillance target through the grid set R; If it is calculated that there are no other surveillance targets in the surveillance area grid where the current surveillance target is located and its adjacent 26 surveillance area grids , the current monitoring target is in a safe state; If it is calculated that there are other surveillance targets in the surveillance area grid where the current surveillance target is located and its adjacent 26 surveillance area grids , then there is a security risk in the current monitoring target and a conflict alarm is issued.

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