A disaster evacuation traffic signal control method and device based on azimuth angle automatic determination and a storage medium

Abstract

The application provides a disaster evacuation traffic signal control method and device based on automatic azimuth angle determination and a storage medium, wherein the method comprises the following steps: determining a disaster influence range and demarcating a radius of an evacuation area based on disaster center coordinates and a disaster level, and selecting all affected intersections in the evacuation area from a city intersection library as evacuation objects; for each intersection in the evacuation objects, calculating a road azimuth angle of each intersection in each road exit direction, a disaster azimuth angle of each intersection pointing to the disaster center, and an included angle between the two, determining a corresponding road direction driving to / from the disaster center based on the calculated included angle, implementing a cut-off on the road driving to the disaster center, implementing an evacuation on the road driving away from the disaster center, and generating a signal control scheme accordingly; and the edge device locally generates and executes a disaster evacuation control scheme based on the signal control scheme to control the state of the intersection traffic signal lamp.

Description

Technical Field

[0001] This invention belongs to the technical field of intelligent traffic emergency management, and in particular relates to a disaster evacuation traffic signal control method, device and storage medium based on automatic azimuth angle determination. Background Technology

[0002] Following a disaster, rapid and orderly traffic evacuation is crucial for minimizing casualties and property damage. Currently, the main technical solutions for traffic signal control in disaster scenarios include: 1. Manual switching of pre-set plans: In this plan, traffic police, upon receiving a disaster report, manually log into the signal control terminals at each intersection and switch to the pre-defined evacuation timing plan one by one. However, this plan is limited by the complexity of the manual operation process, with a single response time typically exceeding 10 minutes, making it difficult to cover a large number of intersections within the golden evacuation window after a disaster. Furthermore, manual judgment of signal strategies in each direction is prone to subjective errors, leading to low evacuation efficiency.

[0003] 2. Pre-set Fixed Evacuation Plan: This plan pre-compiles timing schemes for specific disaster scenarios (such as factory explosions, chemical spills, and other known risk sources) and stores them in the intersection controller. Its technical drawbacks are: the location of disasters is highly random and unpredictable, and the pre-set plan can only cover a limited number of known risk sources. When a disaster occurs at a non-pre-set location, the plan becomes completely ineffective. Furthermore, each new risk source requires a new plan to be compiled and deployed, causing system maintenance costs to increase linearly with the number of risk sources, resulting in poor scalability.

[0004] 3. Single-Intersection Disaster Evacuation Control Scheme: This scheme only adjusts the signal independently at the intersection where the disaster occurs. Common practices include closing all directions with red lights or leaving all directions with green lights. This type of control does not consider the coordination between adjacent intersections, causing evacuation traffic to encounter signal congestion at downstream intersections immediately after leaving the disaster intersection, resulting in secondary congestion. More seriously, the lack of directional differentiation in the all-green light system may cause traffic flows from different directions to cross and conflict within the intersection, leading to secondary traffic accidents.

[0005] 4. Route Planning-Based Evacuation System: This approach relies on a central server for global route planning, assigning optimal evacuation routes to vehicles. However, urban road networks are vast, and global route planning is essentially an NP-hard problem with extremely high computational complexity, resulting in unacceptable response delays in practical applications. Furthermore, this system heavily depends on the continuous availability of the central server and communication network. Disaster sites are often accompanied by damaged communication infrastructure or power outages; once the central link fails, the entire evacuation system will be paralyzed, losing basic control capabilities.

[0006] In summary, existing disaster evacuation signal control technologies generally suffer from the following shortcomings: 1. The system cannot automatically calculate the optimal evacuation strategy for each intersection and each direction based on the actual coordinates of the disaster, resulting in reliance on manual judgment or preset plans, which leads to slow response and narrow coverage. 2. The lack of differentiated directional control capabilities for "allowing vehicles to leave the disaster area" and "intercepting vehicles entering the disaster area" leads to simple and crude red-blocking or green-blocking, which either blocks evacuation channels or introduces conflicting traffic flows. 3. The inability to achieve dynamic mapping between disaster level and impact range, as well as multi-intersection linkage control, results in the inability of single-point control to form a systematic evacuation corridor, and downstream intersections become evacuation bottlenecks; 4. Over-reliance on central servers or communication networks leads to system paralysis after disasters damage infrastructure, indicating a lack of distributed autonomous decision-making capabilities.

[0007] Therefore, there is an urgent need for a method that can automatically generate distributed, directional, and multi-intersection coordinated evacuation signal control based on the location and level of a disaster, in order to overcome the above-mentioned shortcomings of existing technologies. Summary of the Invention

[0008] This invention provides a disaster evacuation traffic signal control method and control device based on automatic azimuth angle determination, which has the advantages of strong adaptability and excellent evacuation effect.

[0009] Other objects and advantages of the present invention can be further understood from the technical features disclosed herein.

[0010] To achieve one, some, or all of the above objectives or other objectives, the present invention provides a disaster evacuation traffic signal control method based on automatic azimuth angle determination. This method receives disaster information, which includes at least the latitude and longitude of the disaster center and the disaster level. Based on the disaster center coordinates and the disaster level, it determines the disaster impact range and delineates the radius of the evacuation area. Based on the delineated evacuation area, it selects all affected intersections within the evacuation area from a city intersection database as evacuation targets, and the intersections immediately adjacent to the outermost affected intersections as coordinated interception targets. The intersections in the coordinated interception targets are located outside the evacuation area and directly connected to the outermost affected intersections. For each intersection in the evacuation targets, it defines a spatial plane coordinate system and coordinates. The system calculates the road azimuth angles of each intersection in all directions, representing the road exit directions. It also calculates the disaster azimuth angle pointing from each intersection to the disaster center. The edge device locally calculates the angle between the road azimuth angle and the disaster azimuth angle, determines the direction of travel towards / away from the disaster center based on the calculated angle, and implements traffic diversion for roads heading towards the disaster center and empties roads leaving the disaster center, generating corresponding signal control schemes. The edge device also implements traffic diversion for the entrance roads of each intersection towards the evacuation area in the coordinated diversion targets and generates signal control schemes. Based on the signal control schemes, the edge device locally generates and executes a disaster evacuation control scheme, controlling the state of the traffic lights at the intersections.

[0011] The calculation of the disaster azimuth angle includes the following steps: Step 1: Calculate the azimuth components of the sphere. The calculation formula is as follows: x=sin(λ2-λ1)×cos(φ2) (1); y=cos(φ1)×sin(φ2)-sin(φ1)×cos(φ2)×cos(λ2-λ1) (2); Where φ1 and λ1 are the intersection coordinates, and φ2 and λ2 are the disaster center coordinates; Step 2: Find the arctangent angle using the following formula: bearing_rad=atan2(x, y) (3); Step 3: Normalize to [0°, 360°), the calculation formula is as follows: bearing_deg=(bearing_rad×180 / π+360)%360 (4); Among them, bearing_deg refers to the azimuth angle from the intersection pointing towards the center of the disaster.

[0012] The disaster evacuation mode has the highest priority in the system. The edge state machine of the edge device receives the disaster evacuation control scheme, interrupts other control modes, and executes the disaster evacuation mode first. The edge state machine sets the traffic lights corresponding to the roads leading to the disaster center to red and the traffic lights corresponding to the roads leaving the disaster center to green.

[0013] The method for determining the direction of travel towards / away from the disaster center based on the calculated angle includes: calculating the original angle difference between the road azimuth angle and the disaster azimuth angle, and normalizing the original angle difference to [0°, 180°]; the method for normalizing the original angle difference to [0°, 180°] is as follows: if the original angle difference is less than 180°, no adjustment is made; if the original angle difference is greater than 180°, the normalized angle difference is obtained by subtracting the calculated original angle difference from 360°; if the normalized angle difference is greater than 90°, the direction of travel is determined to be away from the disaster center; if the normalized angle difference is less than or equal to 90°, the direction determination module determines that the direction of travel is towards the disaster center.

[0014] Before entering the disaster evacuation mode, the edge state machine receives the disaster evacuation control scheme and controls the traffic lights to pass through yellow lights and then all red lights in sequence before switching to evacuation timing. When the edge state machine receives the message to cancel the disaster evacuation mode, it controls the traffic lights to pass through yellow lights and then all red lights in sequence before resuming normal timing.

[0015] The method for selecting all affected intersections within the evacuation area as evacuation targets from the urban intersection database is as follows: The spherical distance from each intersection to the disaster center is calculated sequentially within the intersection database. The calculation method includes the following steps: Step 1: Convert angles to radians. Convert the coordinates of each intersection φ1, λ1 and the coordinates of the disaster center φ2, λ2 into radian values ​​φ1', λ1', φ2', λ2' respectively, where φ and λ are the latitude and longitude of the coordinates, respectively. Step 2: Calculate the difference in radians Δλ' between the longitude and the difference in radians Δφ' between the coordinates of the disaster center and the intersection; Step 3: Calculate the distance value using the following formula: Where R is the Earth's radius; The calculated spherical distance is compared with the radius of the evacuation area, and intersections with a radius less than or equal to that of the evacuation area are selected as evacuation targets.

[0016] Another technical solution of the present invention provides a disaster evacuation traffic signal control device based on automatic azimuth angle determination, comprising a data acquisition layer, a core calculation layer, and an execution control layer; the data acquisition layer receives disaster information, which includes at least the latitude and longitude of the disaster center and the disaster level; the core calculation layer includes a distance filtering module, an azimuth angle calculation module, and a direction determination module; the distance filtering module calculates the spherical distance from each intersection to the disaster center from the intersection database, selects all affected intersections whose spherical distance is less than or equal to the radius of the evacuation area as evacuation targets, and the intersections immediately adjacent to the outermost affected intersections as collaborative interception targets, wherein the intersections in the collaborative interception targets are located outside the evacuation area and are directly connected to the outermost affected intersections; the azimuth angle calculation module defines a spatial plane coordinate system and the angles of each direction of the coordinate system for each intersection in the evacuation targets, and obtains the road exits in each direction of each intersection. The system calculates the road azimuth angle at the intersection; simultaneously, it calculates the disaster azimuth angle pointing from each intersection to the disaster center; and it calculates the angle between the road azimuth angle and the disaster azimuth angle. The direction determination module, for each intersection in the evacuation target, determines the corresponding road direction towards / away from the disaster center based on the calculated angle. The execution control layer includes a scheme generation module and a signal control module. The scheme generation module intercepts roads heading towards the disaster center and empties roads leaving the disaster center, generating corresponding signal control schemes. It also intercepts the entrance roads of each intersection in the collaborative interception target that face the evacuation area and generates signal control schemes. The signal control module generates and executes the disaster evacuation control scheme. After receiving the disaster evacuation control scheme sent by the signal control module, the edge state machine of the edge device switches to disaster evacuation mode and controls the state of the traffic lights at the intersection.

[0017] The azimuth calculation module calculates the disaster azimuth through the following steps: Step 1: Calculate the azimuth components of the sphere. The calculation formula is as follows: x=sin(λ2-λ1)×cos(φ2) (8); y=cos(φ1)×sin(φ2)-sin(φ1)×cos(φ2)×cos(λ2-λ1) (9); Where φ1 and λ1 are the intersection coordinates, and φ2 and λ2 are the disaster center coordinates; Step 2: Find the arctangent angle using the following formula: bearing_rad=atan2(x, y) (10); Step 3: Normalize to [0°, 360°), the calculation formula is as follows: bearing_deg=(bearing_rad×180 / π+360)%360 (11); Among them, bearing_deg refers to the azimuth angle from the intersection pointing towards the center of the disaster; The method by which the azimuth calculation module calculates the angle difference between the road azimuth and the disaster azimuth is as follows: The original angle difference between the road azimuth and the disaster azimuth is calculated and normalized to [0°, 180°]. The method for normalizing the original angle difference to [0°, 180°] is as follows: If the original angle difference is less than 180°, no adjustment is made; if the original angle difference is greater than 180°, the normalized angle difference is obtained by subtracting the calculated original angle difference from 360°; if the normalized angle difference is greater than 90°, the direction determination module determines that the corresponding road direction is away from the disaster center; if the normalized angle difference is less than or equal to 90°, the corresponding road direction is towards the disaster center.

[0018] After receiving the disaster evacuation control plan sent by the signal control module, the edge state machine of the edge device controls the signal lights to pass through yellow lights and then all red lights in sequence before entering the disaster evacuation mode and then switching to evacuation timing. When the edge state machine receives the signal control module to cancel the disaster evacuation mode, the edge state machine controls the signal lights to pass through yellow lights and then all red lights in sequence before resuming normal timing.

[0019] Another technical solution of the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the steps in the disaster evacuation traffic signal control method based on automatic azimuth angle determination described above.

[0020] Compared with existing technologies, the beneficial effects of this invention mainly include: 1. This invention determines the scope of disaster impact based on the coordinates and level of the disaster center, delineates evacuation areas, calculates the spherical distance between each intersection in the intersection database and the disaster center, compares it with the radius of the evacuation area, automatically filters affected intersections, and calculates the disaster azimuth angle, road azimuth angle, and the angle between them. Using the calculated angle as the judgment criterion, it independently generates an "exit release" or "entry interception" strategy for each intersection and each direction. Compared with the high response delay of the manual switching scheme in the prior art, the solution of this application has the advantages of fast response and the ability to cover sudden disasters in any location in the city. 2. This invention automatically filters affected intersections and generates an independent evacuation strategy for each intersection. All intersections are based on the same judgment rule, which can generate continuous evacuation corridors. That is, all roads leading to the disaster center are intercepted, and all roads leaving the disaster center are emptied, forming a continuous evacuation channel. This solves the problem that the existing technology cannot achieve intersection linkage when controlling a single intersection. 3. The control commands of this invention are issued via traffic lights, eliminating the need for vehicle-mounted communication or dedicated terminals, thus offering the advantage of wide applicability. Furthermore, the issuance of control signals can be achieved through edge devices, enabling autonomous operation even when the network is disconnected, avoiding the problem of evacuation commands failing to be issued due to communication link failures.

[0021] To make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a system architecture diagram of a disaster evacuation traffic signal control device according to the present invention.

[0024] Figure 2 This is a schematic diagram illustrating the principle of evacuation direction determination in this invention.

[0025] Figure 3 This is a schematic diagram of the intersection screening method of the present invention.

[0026] Figure 4 This is a schematic diagram illustrating the disaster classification response range of the present invention.

[0027] Figure 5 This is a schematic diagram of the evacuation strategy for a single intersection according to the present invention.

[0028] Figure 6 This is a schematic diagram of the multi-intersection linkage evacuation corridor of the present invention.

[0029] Figure 7 This is a timing diagram of the state transition of traffic lights controlled by the edge state machine of the present invention.

[0030] Figure 8 This is a diagram showing the relationship between mode priority and interruption in this invention. Detailed Implementation

[0031] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the accompanying drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front, or back, are merely for reference to the accompanying drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the present invention.

[0032] Example 1 Example 1 provides a disaster evacuation traffic signal control method based on automatic azimuth angle determination. The method includes receiving disaster information, which at least includes the latitude and longitude of the disaster center and the disaster level; determining the disaster impact range and delineating the radius of the evacuation area based on the disaster center coordinates and the disaster level; selecting all affected intersections within the evacuation area as evacuation targets from a city intersection database, and selecting the intersections immediately adjacent to the outermost affected intersections as coordinated interception targets. The intersections in the coordinated interception targets are located outside the evacuation area and directly connected to the outermost affected intersections; and defining a spatial plane coordinate system and angles in each direction for each intersection in the evacuation targets. The system obtains the road azimuth angles of each intersection's outbound direction; calculates the disaster azimuth angle of each intersection pointing towards the disaster center; the edge device locally calculates the angle between the road azimuth angle and the disaster azimuth angle, determines the corresponding road direction towards / away from the disaster center based on the calculated angle, and implements traffic diversion on roads heading towards the disaster center and empties roads leaving the disaster center, and generates corresponding signal control schemes; the edge device implements traffic diversion on the inbound roads of each intersection in the coordinated diversion targets facing the evacuation area, and generates signal control schemes; the edge device locally generates and executes a disaster evacuation control scheme based on the signal control scheme, controlling the state of the intersection traffic lights. Example 1 provides a disaster evacuation traffic signal control method based on automatic azimuth angle determination. Based on the latitude and longitude of the disaster center, it calculates the spherical distance from each intersection in the intersection database to the disaster center. Based on disaster information, it delineates evacuation areas and includes all affected intersections. Example 1 determines the direction of travel towards / away from the disaster center based on the calculated road azimuth angle and the angle between the disaster azimuth angle and the road azimuth angle. It then generates evacuation strategies for each direction of each intersection. These evacuation strategies are executed by the edge state machine of the edge device, controlling the state of the corresponding traffic lights to achieve the evacuation strategy. The technical solution provided in Example 1 has the advantages of rapid response and the ability to cover sudden disasters in any location within the city.

[0033] The following, in conjunction with the accompanying drawings, provides a detailed explanation of a disaster evacuation traffic signal control method based on automatic azimuth angle determination, as described in this application. Figure 2-8 As shown, the disaster evacuation traffic signal control method based on automatic azimuth angle determination of this application includes the following steps: Step 1: Receive disaster information and determine the radius of the evacuation area based on the disaster information.

[0034] The system receives disaster information, including the coordinates (latitude and longitude) of the disaster center and the disaster level. Based on the mapping relationship between the disaster level and the radius of influence, it determines the spatial range that needs to be included in the control.

[0035] As an optional implementation method, such as Figure 4 As shown, the mapping relationship between disaster level and impact radius includes three levels: Level I, Level II, and Level III. Level I disasters correspond to earthquakes, with an evacuation range covering the entire city. Level II disasters correspond to floods and large-scale accidents, with an evacuation range within 3 km of the disaster center. Level III disasters correspond to localized accidents / fires, with an evacuation range within 1 km of the disaster center. For Level II and Level III disasters, the impact radius can be customized by overriding the default value through the radius_km field (a geographic data field whose standard unit of measurement is kilometers, used to define the radius of a circular area extending outward from a defined point). This allows emergency command personnel to dynamically adjust the response range according to the actual disaster scale without modifying the system configuration. Level I disasters always cover the entire city, and the radius_km parameter is ignored.

[0036] Step 2: Select intersections within the intersection database based on the defined evacuation radius.

[0037] Step 2-1: Select all affected intersections within the evacuation area from the city intersection database as evacuation targets.

[0038] like Figure 3As shown, the city intersection database contains information on every intersection. The spherical distance of each intersection in the database from the disaster center is calculated. Based on the calculated distance, the calculated distance is compared with the evacuation radius, and all intersections whose spherical distance is less than or equal to the evacuation radius are selected as evacuation targets.

[0039] Calculating the spherical distance from each intersection within the intersection database to the disaster center involves the following steps: Step 2-1-1: Convert angles to radians. Convert the coordinates of each intersection φ1, λ1 and the disaster center coordinates φ2, λ2 into radian values ​​φ1', λ1', φ2', λ2', respectively, where φ and λ are the latitude and longitude of the coordinates, respectively. Step 2-1-2: Calculate the difference in radians Δλ' between the longitude and the difference in radians Δφ' between the coordinates of the disaster center and the intersection; Step 2-1-3: Calculate the distance value. The calculation formula is as follows: Where R is the Earth's radius.

[0040] The atan2(x, y) function calculates the azimuth angle based on the position of a coordinate point and returns a value in radians. Its calculation process can be divided into three core steps: 1. Calculate the value of y / x; 2. Obtain the base angle of arctan(x / y); 3. Quadrant correction, adjusting the final angle value based on the signs of x and y. Solving the atan2(x, y) function is existing technology and will not be described in detail here.

[0041] Based on the calculated distance value, this value is compared with the defined evacuation radius, and intersections within the evacuation radius are included in the evacuation.

[0042] Step 2-2: Select the outermost affected intersection and the intersection immediately adjacent to it in the city intersection database as the collaborative interception target. The intersection in the collaborative interception target is located outside the evacuation area and is directly connected to the outermost affected intersection.

[0043] The selected collaborative interception targets are intersections that should be included in collaborative control, in addition to those whose evacuation radius is affected. When generating evacuation strategies, their role is to prevent traffic flow outside the evacuation area from entering the evacuation area.

[0044] Step 3: For each intersection in the evacuation area, calculate the disaster azimuth angle, the road azimuth angle, and the angle between the two.

[0045] Step 3-1: Calculate the azimuth of the disaster.

[0046] Calculating the azimuth of a disaster includes the following steps. Step 3-1-1: Calculate the azimuth components of the sphere. The calculation formula is as follows: x=sin(λ2-λ1)×cos(φ2) (4); y=cos(φ1)×sin(φ2)-sin(φ1)×cos(φ2)×cos(λ2-λ1) (5); Where φ1 and λ1 are the intersection coordinates, and φ2 and λ2 are the disaster center coordinates; Step 3-1-2: Find the arctangent angle using the following formula: bearing_rad=atan2(x, y) (6); Step 3-1-3: Normalize to [0°, 360°), the calculation formula is as follows: bearing_deg=(bearing_rad×180 / π+360)%360 (7); Among them, bearing_deg refers to the azimuth angle from the intersection towards the center of the disaster, which is also known as the disaster azimuth angle.

[0047] Step 3-2: Calculate the road azimuth.

[0048] Define a spatial plane coordinate system and the angles in each direction of the coordinate system.

[0049] Define four directions—east, south, west, and north—on a spatial plane, and define one direction as 0°. Then, define the angles of the remaining directions (ranging from 0° to 360°) according to the given direction (clockwise or counterclockwise). Figure 2 For example, we define north as 0°, and define the angles for other directions clockwise. That is, east-facing roads are 90°, south-facing roads are 180°, and west-facing roads are 270°. All roads are set perpendicular to the intersection. If the road is not perpendicular to the intersection, the road azimuth angle can be calculated based on the actual angle.

[0050] Step 3-3: Calculate the angle between the disaster azimuth and the road azimuth.

[0051] Calculating the angle between the disaster azimuth and the road azimuth includes calculating the original angle difference between the road azimuth and the disaster azimuth, and normalizing the original angle difference to [0°, 180°]. The method for normalizing the original angle difference to [0°, 180°] is as follows: if the original angle difference is less than 180°, no adjustment is made; if the original angle difference is greater than 180°, the normalized angle difference is obtained by subtracting the calculated original angle difference from 360°.

[0052] Step 4: Generate a signal control scheme.

[0053] The edge device determines the direction of travel towards / away from the disaster center based on the calculated angle (the direction of travel is the direction in which the vehicle travels along the road; in this application, the direction of travel refers to the direction of the road exit), and implements traffic diversion on the road heading towards the disaster center and emptying the road leaving the disaster center, and generates a corresponding signal control scheme.

[0054] Specifically, if the normalized angle difference is greater than 90°, it is determined that the corresponding road direction is away from the disaster center, and the traffic light corresponding to the road direction away from the disaster center is set to green.

[0055] If the normalized angle difference is ≤90°, then the corresponding road direction is determined to be heading towards the disaster center, and the traffic light corresponding to the road heading towards the disaster center is set to red.

[0056] The edge device intercepts traffic at each intersection in the collaborative interception target that faces the evacuation area, and generates a signal control scheme to set the traffic lights corresponding to the entrance roads leading to the evacuation area to red. Other directions that do not enter the evacuation area should not interfere with normal traffic in principle.

[0057] by Figure 2 For example, when the disaster center is located at a 45° northeast angle from the intersection, the calculated angles of the roads in each direction are: North: 45°, East: 45°, South: 135°, West: 135°. Therefore, based on the calculated angles, the traffic lights for the north and east directions are set to red, indicating that the road is under traffic control; the traffic lights for the south and west directions are set to green, indicating that the road is under drainage control.

[0058] When the disaster direction is located at an intersection or along the horizontal extension of the intersection, there are two directions with a calculated angle of 90°. For safety, in this case, the traffic light status of the road corresponding to the 90° angle is also set to red. Figure 5 For example, if the disaster direction is due east of the intersection, the calculated angle of the eastbound road is 0°, indicating the road is heading towards the disaster center and should be classified as a closure. The calculated angles of the southbound and northbound roads are both 90°; to ensure system safety, a conservative strategy should be adopted, classifying these two intersections as closures as well. The calculated angle of the westbound road is 180°, indicating the road is moving away from the disaster center, and this road should be classified as a drainage point.

[0059] In this application's solution, based on the angle determination rule, the control status of each direction of the road at each intersection is determined, enabling the linkage of multiple intersections to form a continuous evacuation corridor. Specifically, as... Figure 6As shown, each intersection is calculated independently based on its position relative to the disaster center, with unified judgment rules. Each intersection generates an independent control plan based on the judgment rules, and the differentiated plans of multiple intersections work together to form a coordinated evacuation corridor. At this time, intersections closer to the disaster center evacuate quickly, intermediate intersections take over, and outer intersections intercept traffic on roads leading to the evacuation area. The coordinated operation of multiple intersections improves evacuation efficiency and avoids chaos during evacuation.

[0060] Step 5: The edge device generates and executes the disaster evacuation control scheme locally based on the signal control scheme.

[0061] The disaster evacuation mode has the highest priority in the system. The edge state machine of the edge device receives the disaster evacuation control scheme, interrupts other control modes, and switches to the disaster evacuation mode.

[0062] like Figure 8 As shown, the system signals received by the edge state machine correspond to system modes with different priorities. The edge state machine determines the execution order based on the priority of the system modes in the received system signals. Specifically, in this application, based on the disaster level in the received disaster information, a disaster evacuation control scheme is generated after confirming a disaster requiring evacuation. This disaster evacuation control scheme is transmitted to the edge state machine as a system signal. After parsing the disaster evacuation control scheme, the edge state machine switches to the disaster evacuation mode. This disaster evacuation mode has the highest priority in the system and can interrupt other system modes (e.g., the disaster evacuation mode can interrupt the special vehicle priority mode, the accident circuit breaker mode, the normal operation mode, and the yellow flashing mode).

[0063] The priority rules include: 1. Disaster evacuation mode can interrupt priority for special vehicles, accident circuit breaker and normal operation.

[0064] 2. During disaster evacuation mode, low-priority mode switching requests are rejected.

[0065] 3. Disaster evacuation mode can only be exited when the emergency command center sends a disaster cancellation order or the evacuation duration exceeds the predetermined limit.

[0066] 4. The default duration of the disaster evacuation mode is 90 seconds, after which it will automatically exit.

[0067] In this application, the activation condition for the disaster evacuation mode is receiving disaster information containing valid coordinates and level. The conditions for exiting the disaster evacuation mode are receiving a disaster relief order from the emergency command center or the evacuation duration exceeding a predetermined limit (default 90s).

[0068] Entering and exiting disaster evacuation mode must go through a safe clearing phase to ensure that all vehicles at the intersection have passed before switching signals.

[0069] Before entering disaster evacuation mode, the edge state machine receives the evacuation control plan. The state machine control lights sequentially pass through yellow lights, then all red lights, before switching to evacuation timing. When the state machine receives the de-disaster evacuation mode, the edge state machine control signals sequentially pass through yellow lights, then all red lights, before resuming normal timing.

[0070] As an alternative approach, before the edge state machine switches to the yellow light, it can maintain the current phase of the traffic light state for the entire time before executing the traffic light switch, thus avoiding sudden changes in traffic lights that may cause the driver to be unable to react in time and reducing the probability of accidents.

[0071] Understandably, all traffic lights at an intersection turn red after the yellow light and remain red for a short period (i.e., clearing the intersection completely), allowing vehicles that entered the intersection during the yellow light period to safely exit, avoiding conflicts with vehicles in the next phase, and eliminating congested vehicles at the intersection. Simultaneously setting all traffic lights to red and maintaining this position clears the intersection of vehicles, ensuring safety during signal switching and reducing the probability of accidents.

[0072] by Figure 7 Taking the timing sequence as an example, if the current phase is running with a green light, before the edge state machine needs to switch to the disaster evacuation mode, it needs to switch the state of the traffic lights. At this time, after the edge state machine controls the traffic lights of the current phase to complete the remaining time (i.e., after the green light ends), they will pass through the yellow light and then all red light before the evacuation timing takes effect. The edge state machine controls the traffic lights corresponding to each direction of each intersection to execute the signal control scheme. The holding time for the yellow light and all red light clearing is 3 seconds each.

[0073] Similarly, when the state machine receives the message to exit the disaster evacuation mode, the evacuation timing will sequentially pass through the yellow light and then be cleared by all red lights before gradually returning to normal timing.

[0074] The safe clearance time ensures that vehicles currently passing through the intersection have enough time to exit the intersection area, preventing cross-traffic conflicts that may occur during signal switching.

[0075] In this application, the edge state machine is based on the evacuation control scheme and controls the color of the traffic lights at the intersection. The edge state machine does not communicate directly with the vehicles. The corresponding evacuation control scheme is transmitted to the driver through the color display of the traffic lights. Since it does not rely on vehicle communication or dedicated terminals, the scheme has universality and feasibility.

[0076] Based on the above scheme mentioned in Example 1, performance testing was conducted using simulated intersection grid data under a standard testing environment (Windows 11 / Python 3.11 / ordinary x86 platform). The test scale was 100 intersections, and the disaster azimuth angle, road azimuth angle, and the angle between the two were calculated for the 100 intersections. The measured result was 2.2ms, while the design target was less than or equal to 500ms. The measured result met the design target.

[0077] When the test scale was 500 intersections, the measured result was 10.1ms, while the design target was less than or equal to 2300ms. The measured result met the design target.

[0078] The test results show that the generation of evacuation plans for 100 intersections took 2.2ms, and the stress test for 500 intersections took 10.1ms, which meets the system objective of signal activation within 30 seconds after a disaster (including communication delay and safe transition time).

[0079] The disaster evacuation traffic signal control method based on automatic azimuth angle determination provided in Example 1 has all core calculations completed locally on the edge device. Even when communication is interrupted, the disaster evacuation control scheme can still be triggered and executed. It does not rely on real-time path planning and preset plans of the central server and has high reliability.

[0080] Example 2 Example 2 provides a disaster evacuation traffic signal control device based on automatic azimuth angle determination, such as... Figure 1 The diagram shows the data acquisition layer, the core computing layer, and the execution control layer. The data acquisition layer receives disaster information, which includes at least the latitude and longitude of the disaster center and the disaster level; the core calculation layer includes a distance filtering module, an azimuth calculation module, and a direction determination module.

[0081] The distance filtering module calculates the spherical distance from each intersection in the intersection database to the disaster center one by one, selects all affected intersections whose spherical distance is less than or equal to the radius of the evacuation area as evacuation targets, and selects the intersections immediately adjacent to the outermost affected intersections as collaborative interception targets. The intersections in the collaborative interception targets are located outside the evacuation area and are directly connected to the outermost affected intersections.

[0082] The distance filtering module's calculation includes the following steps: Step 1: Convert angles to radians. Convert the coordinates of each intersection φ1, λ1 and the coordinates of the disaster center φ2, λ2 into radian values ​​φ1', λ1', φ2', λ2' respectively, where φ and λ are the latitude and longitude of the coordinates, respectively. Step 2: Calculate the difference in radians Δλ' between the longitude and the difference in radians Δφ' between the coordinates of the disaster center and the intersection; Step 3: Calculate the distance value using the following formula: Where R is the Earth's radius.

[0083] The atan2(x, y) function calculates the azimuth angle based on the position of a coordinate point and returns a value in radians. Its calculation process can be divided into three core steps: 1. Calculate the value of y / x; 2. Obtain the base angle of arctan(x / y); 3. Quadrant correction, adjusting the final angle value based on the signs of x and y. Solving the atan2(x, y) function is existing technology and will not be described in detail here.

[0084] The azimuth calculation module defines a spatial plane coordinate system and the angles of each direction in the coordinate system for each intersection in the evacuation target, and obtains the road azimuth angle of each intersection in each direction of the road exit direction; at the same time, it calculates the disaster azimuth angle of each intersection pointing to the disaster center; and calculates the angle between the road azimuth angle and the disaster azimuth angle. The azimuth calculation module calculates the disaster azimuth through the following steps: Step 1: Calculate the azimuth components of the sphere. The calculation formula is as follows: x=sin(λ2-λ1)×cos(φ2) (11); y=cos(φ1)×sin(φ2)-sin(φ1)×cos(φ2)×cos(λ2-λ1) (12); Where φ1 and λ1 are the intersection coordinates, and φ2 and λ2 are the disaster center coordinates; Step 2: Find the arctangent angle using the following formula: bearing_rad=atan2(x, y) (13); Step 3: Normalize to [0°, 360°), the calculation formula is as follows: bearing_deg=(bearing_rad×180 / π+360)%360 (14); Among them, bearing_deg refers to the azimuth angle from the intersection pointing towards the center of the disaster; The method for the azimuth calculation module to calculate the angle difference between the road azimuth and the disaster azimuth is to calculate the original angle difference between the road azimuth and the disaster azimuth and normalize the original angle difference to [0°, 180°]. The method for normalizing the original angle difference to [0°, 180°] is as follows: if the original angle difference is less than 180°, no adjustment is made; if the original angle difference is greater than 180°, the normalized angle difference is obtained by subtracting the calculated original angle difference from 360°.

[0085] The direction determination module determines the direction of travel towards / away from the disaster center for each intersection in the evacuation area based on the calculated included angle. If the normalized angle difference is greater than 90°, the direction determination module determines that the corresponding road direction is away from the disaster center; if the normalized angle difference is less than or equal to 90°, the direction determination module determines that the corresponding road direction is towards the disaster center.

[0086] The execution control layer includes a scheme generation module and a signal control module. The scheme generation module intercepts roads leading to the disaster center and empties roads leaving the disaster center, and generates corresponding signal control schemes. It also intercepts the entrance roads of each intersection facing the evacuation area in the coordinated interception objects and generates signal control schemes. The signal control module generates and executes the disaster evacuation control scheme. After receiving the disaster evacuation control scheme sent by the signal control module, the edge state machine of the edge device switches to the disaster evacuation mode and controls the state of the traffic lights at the intersection.

[0087] After receiving the disaster evacuation control plan sent by the signal control module, the edge state machine of the edge device controls the signal lights to pass through yellow lights and then all red lights in sequence before entering the disaster evacuation mode and then switching to evacuation timing. When the edge state machine receives the signal control module to cancel the disaster evacuation mode, the edge state machine controls the signal lights to pass through yellow lights and then all red lights in sequence before resuming normal timing.

[0088] Example 2 provides a disaster evacuation traffic signal control device for implementing the steps of the disaster evacuation traffic signal control method based on automatic azimuth angle determination in Example 1.

[0089] Example 3 Example 3 provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the steps in the disaster evacuation traffic signal control method based on automatic azimuth angle determination described in Example 1.

[0090] The foregoing has provided a detailed description of a disaster evacuation traffic signal control method, device, and storage medium based on automatic azimuth angle determination provided by the present invention. Specific examples have been used to illustrate the structure and working principle of the invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A disaster evacuation traffic signal control method based on automatic azimuth angle determination, characterized in that, Receive disaster information, which includes at least the latitude and longitude of the disaster center and the disaster level; Based on the disaster center coordinates and disaster level, the scope of disaster impact is determined and the radius of the evacuation area is delineated. Based on the delineated evacuation area, all affected intersections within the evacuation area are selected as evacuation targets in the urban intersection database, and the intersections adjacent to the outermost affected intersections are selected as collaborative interception targets. The intersections in the collaborative interception targets are located outside the evacuation area and are directly connected to the outermost affected intersections. For each intersection in the evacuation target, a spatial plane coordinate system and the angles of each direction in the coordinate system are defined to obtain the road azimuth angles of each intersection in the direction of the road exit. Calculate the azimuth angle of each intersection pointing towards the center of the disaster; The edge device locally calculates the angle between the road azimuth and the disaster azimuth, determines the direction of the corresponding road towards / away from the disaster center based on the calculated angle, and implements traffic diversion on the road towards the disaster center and drainage on the road away from the disaster center, and generates a corresponding signal control scheme. The edge device intercepts the incoming roads of each intersection in the collaborative interception object that are facing the evacuation area, and generates a signal control scheme. The edge device generates and executes a disaster evacuation control scheme locally based on the signal control scheme, and controls the state of traffic lights at the intersection.

2. The disaster evacuation traffic signal control method based on automatic azimuth angle determination according to claim 1, characterized in that, The calculation of the disaster azimuth angle includes the following steps: Step 1: Calculate the azimuth components of the sphere. The calculation formula is as follows: x=sin(λ2-λ1)×cos(φ2) (1); y=cos(φ1)×sin(φ2)-sin(φ1)×cos(φ2)×cos(λ2-λ1) (2); Where φ1 and λ1 are the intersection coordinates, and φ2 and λ2 are the disaster center coordinates; Step 2: Find the arctangent angle using the following formula: bearing_rad=atan2(x, y) (3); Step 3: Normalize to [0°, 360°), the calculation formula is as follows: bearing_deg=(bearing_rad×180 / π+360)%360 (4); Among them, bearing_deg refers to the azimuth angle from the intersection pointing towards the center of the disaster.

3. The disaster evacuation traffic signal control method based on automatic azimuth angle determination according to claim 2, characterized in that, The disaster evacuation mode has the highest priority in the system. The edge state machine of the edge device receives the disaster evacuation control scheme, interrupts other control modes, and executes the disaster evacuation mode first. The edge state machine sets the traffic lights corresponding to roads heading towards the disaster center to red and the traffic lights corresponding to roads heading away from the disaster center to green.

4. The disaster evacuation traffic signal control method based on automatic azimuth angle determination according to claim 3, characterized in that, Determining the direction of the road towards / away from the disaster center based on the calculated included: calculating the original angle difference between the road azimuth and the disaster azimuth, and normalizing the original angle difference to [0°, 180°]; The method for normalizing the original angle difference to [0°, 180°] is as follows: if the original angle difference is less than 180°, no adjustment is made; if the original angle difference is greater than 180°, the normalized angle difference is obtained by subtracting the calculated original angle difference from 360°. If the normalized angle difference is greater than 90°, it is determined that the corresponding road direction is away from the disaster center; If the normalized angle difference is ≤90°, then the corresponding road direction is determined to be heading towards the disaster center.

5. The disaster evacuation traffic signal control method based on automatic azimuth angle determination according to claim 3, characterized in that, The edge state machine receives the disaster evacuation control scheme. Before entering the disaster evacuation mode, the edge state machine controls the traffic lights to pass through yellow lights and then all red lights in sequence before switching to evacuation timing. When the edge state machine receives the signal to cancel the disaster evacuation mode, the edge state machine controls the signal to pass through the yellow light and then the red light in sequence before restoring the normal timing.

6. The disaster evacuation traffic signal control method based on automatic azimuth angle determination according to claim 1, characterized in that, The method for selecting all affected intersections within the evacuation area as evacuation targets from the urban intersection database is as follows: The spherical distance from each intersection to the disaster center is calculated sequentially within the intersection database. The calculation method includes the following steps: Step 1: Convert angles to radians. Convert the coordinates of each intersection φ1, λ1 and the coordinates of the disaster center φ2, λ2 into radian values ​​φ1', λ1', φ2', λ2' respectively, where φ and λ are the latitude and longitude of the coordinates, respectively. Step 2: Calculate the difference in radians Δλ' between the longitude and the difference in radians Δφ' between the coordinates of the disaster center and the intersection; Step 3: Calculate the distance value using the following formula: Where R is the Earth's radius; The calculated spherical distance is compared with the radius of the evacuation area, and intersections with a radius less than or equal to that of the evacuation area are selected as evacuation targets.

7. A disaster evacuation traffic signal control device based on automatic azimuth angle determination, characterized in that, It includes a data acquisition layer, a core computing layer, and an execution control layer; The data acquisition layer receives disaster information, which includes at least the latitude and longitude of the disaster center and the disaster level. The core computing layer includes a distance filtering module, an azimuth calculation module, and a direction determination module; The distance filtering module calculates the spherical distance from each intersection to the disaster center from the intersection database one by one, selects all affected intersections whose spherical distance is less than or equal to the radius of the evacuation area as evacuation targets, and the intersections immediately adjacent to the outermost affected intersections as collaborative interception targets. The intersections in the collaborative interception targets are located outside the evacuation area and are directly connected to the outermost affected intersections. The azimuth calculation module defines a spatial plane coordinate system and the angles of each direction in the coordinate system for each intersection in the evacuation target, and obtains the road azimuth angle of each intersection in each direction of the road exit direction; at the same time, it calculates the disaster azimuth angle of each intersection pointing to the disaster center; and calculates the angle between the road azimuth angle and the disaster azimuth angle. The direction determination module, for each intersection among the evacuation targets, determines the corresponding road direction towards / away from the disaster center based on the calculated included angle; The execution control layer includes a scheme generation module and a signal control module. The scheme generation module intercepts roads leading to the disaster center and empties roads leaving the disaster center, and generates corresponding signal control schemes. It also intercepts the entrance roads of each intersection facing the evacuation area in the coordinated interception objects and generates signal control schemes. The signal control module generates and executes a disaster evacuation control scheme. After receiving the disaster evacuation control scheme sent by the signal control module, the edge state machine of the edge device switches to the disaster evacuation mode and controls the state of the traffic lights at the intersection.

8. A disaster evacuation traffic signal control device according to claim 7, characterized in that, The azimuth calculation module calculates the disaster azimuth through the following steps: Step 1: Calculate the azimuth components of the sphere. The calculation formula is as follows: x=sin(λ2-λ1)×cos(φ2) (8); y=cos(φ1)×sin(φ2)-sin(φ1)×cos(φ2)×cos(λ2-λ1) (9); Where φ1 and λ1 are the intersection coordinates, and φ2 and λ2 are the disaster center coordinates; Step 2: Find the arctangent angle using the following formula: bearing_rad=atan2(x, y) (10); Step 3: Normalize to [0°, 360°), the calculation formula is as follows: bearing_deg=(bearing_rad×180 / π+360)%360 (11); Among them, bearing_deg refers to the azimuth angle from the intersection pointing towards the center of the disaster; The method for the azimuth calculation module to calculate the angle difference between the road azimuth and the disaster azimuth is to calculate the original angle difference between the road azimuth and the disaster azimuth and normalize the original angle difference to [0°, 180°]. The method for normalizing the original angle difference to [0°, 180°] is as follows: if the original angle difference is less than 180°, no adjustment is made; if the original angle difference is greater than 180°, the normalized angle difference is obtained by subtracting the calculated original angle difference from 360°. If the normalized angle difference is greater than 90°, the direction determination module determines that the corresponding road direction is away from the disaster center; If the normalized angle difference is ≤90°, the direction determination module determines that the corresponding road direction is heading towards the disaster center.

9. A disaster evacuation traffic signal control device according to claim 7, characterized in that, After receiving the disaster evacuation control scheme sent by the signal control module, the edge state machine of the edge device controls the signal lights to pass through yellow lights and then all red lights in sequence before entering the disaster evacuation mode and then switching to evacuation timing. When the edge state machine receives the signal control module's message to cancel the disaster evacuation mode, the edge state machine controls the signal to pass through the yellow light and then the red light in sequence before restoring the normal timing.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the disaster evacuation traffic signal control method based on automatic azimuth angle determination according to any one of claims 1-6.

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