A method for identifying flow direction at intersection entrances with priority passage on escorted routes

Abstract

The present invention relates to the field of traffic technology and discloses a method for identifying flow directions at intersection entrances with priority access on escorted routes. The method comprises obtaining navigation route trajectory data and sequentially numbering the trajectory points; matching intersections along the trajectory path based on intersection latitude and longitude information to generate a sequence of sequentially arranged intersections; determining the entrance direction at the first intersection by matching the angle between the forward trajectory vector and the vector of the adjacent intersection based on intersection adjacency data; determining the exit direction at the last intersection by matching the angle between the backward trajectory vector and the vector of the adjacent intersection based on the adjacent intersection relationship data; dividing the driving flow direction angle ranges according to the entrance direction angle, and matching the exit direction angle with the angle range to determine the driving flow direction; and verifying the identified flow direction in combination with the lane flow attributes of the entrance, and outputting the flow direction information. This method solves the problems of tedious manual calibration and poor error tolerance in the prior art, achieving the goals of dynamic route adaptation, intelligent flow direction determination, and dual verification and correction.

Description

Technical Field

[0001] The present invention relates to the technical field of signal devices, in particular to traffic. Background Art

[0002] With the acceleration of urbanization, urban road networks are becoming increasingly complex, and traffic signal control systems are densely covering major road nodes. While this improves normal traffic efficiency, it also creates challenges for special-service vehicles (such as ambulances, fire trucks, and police cars) performing emergency operations. Delays due to traffic light restrictions are common. Traditional special-service priority access solutions rely on a static, manual configuration model, which suffers from systemic technical limitations. Traditional methods rely on manual pre-planning of fixed routes. Operators must manually annotate the entrance direction (e.g., east entrance, west entrance) and traffic flow (left turn, straight ahead, right turn) at each intersection on the control platform. For example, if an escort route from a fire station to a key unit passes through 20 intersections, 40 key parameters (entrance and flow direction at each intersection) must be manually confirmed. This configuration process requires subjective judgment based on paper road network maps and historical experience, takes hours, and is unable to adapt to temporary adjustments.

[0003] The preset routes of existing technologies are unable to respond to real-time traffic conditions. When an accident occurs on a certain road section, special service vehicles need to detour, but the system still applies signal priority according to the original route, causing the actual driving path to deviate from the system's preset path. Critical intersections are not included in the priority release range, and non-essential intersections are mistakenly triggered to trigger green lights, causing traffic disruption. Urban road network reconstruction (such as adding ramps and adjusting intersection channels) will lead to high manual maintenance costs, prone to entrance direction marking errors, and flow configurations that do not match the actual function of the lane (such as the preset left turn but the lane has been changed to a straight right). Emergency tasks are highly uncertain. For example, an ambulance may temporarily change its destination due to hospital occupancy, and a fire may spread, requiring fire trucks to dynamically adjust their travel direction. Current traditional systems cannot support this type of real-time path reconstruction.

[0004] Problems with current existing technologies can lead to manual configuration delays, causing special service vehicles to wait an average of 1-2 more signal cycles at intersections. False triggering of priority phases can cause secondary congestion, and frequent misjudgments lead traffic management departments to adopt a conservative attitude towards automated priority mechanisms.

[0005] For example, Chinese patent publication number CN111489571B discloses a V2X-based vehicle intersection priority passage method and system, and provides the following technical solutions. The present invention belongs to the field of vehicle networking and discloses a V2X-based vehicle intersection priority passage method and system. The method is as follows: a roadside communication terminal is provided with an RSU to receive collected intersection map information and broadcast it to all vehicles' onboard OBUs; the onboard terminal OBU downloads the intersection map information sent by the RSU, and compares it with the real-time position of the vehicle uploaded by the onboard GPS. The vehicle's real-time position and map configuration algorithm are used to calculate and match the vehicle position and intersection map information in real time. When the priority condition is triggered, a command is sent to the traffic light via Ethernet. The system includes an onboard communication terminal OBU, a roadside communication terminal RSU, and an intelligent traffic light. The present invention can maximize the efficiency of special vehicles' intersection passage and solve the problem of special vehicles' priority passage. However, the above-mentioned V2X-based vehicle intersection priority passage method and system cannot dynamically plan routes, relies on manually preset maps and calibration parameters, cannot automatically identify the entrance flow direction of vehicles at any intersection, and the system fails when the vehicle deviates from the preset route. Summary of the Invention

[0006] This invention addresses the existing issues of cumbersome manual calibration, lack of flow direction identification, and poor fault tolerance. It proposes a method for identifying flow direction at intersection entrances for priority passage on escort routes, achieving dynamic route adaptation, intelligent flow direction determination, dual verification and correction, and fully automated execution. This method primarily addresses the issue of special service vehicles arriving at intersections, where unknown flow direction information at the entrance prevents the signal control system from identifying the priority release phase. This approach reduces travel time for special service vehicles on the road.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for identifying flow directions at intersection entrances with priority passage on escorted routes, comprising:

[0009] Obtain navigation route trajectory data and number the trajectory points in sequence; match the intersections along the trajectory based on the intersection latitude and longitude information to generate a sequence of intersections arranged in sequence;

[0010] Based on the intersection adjacent relationship data, the first intersection determines the entrance direction by matching the angle between the forward trajectory vector and the vector of the adjacent intersection. The last intersection determines the exit direction by matching the angle between the backward trajectory vector and the vector of the adjacent intersection. The middle intersection determines the entrance and exit directions based on the relationship between adjacent intersections.

[0011] The driving direction is divided into angle ranges according to the entrance direction angle, and the exit direction angle is matched with the angle range to determine the driving direction; the identified flow direction is verified in combination with the lane flow attributes at the intersection entrance, and the flow direction information is output.

[0012] By automatically processing navigation trajectory data and intersection information, manual intervention is reduced and recognition efficiency is improved. At the same time, combined with secondary verification of angle range and lane attributes, the accuracy and reliability of flow direction recognition are enhanced, ensuring that the signal control system can respond quickly when special service vehicles have priority passage, thereby reducing travel time.

[0013] Preferably, the first intersection determines the entrance direction by matching the angle between the forward trajectory vector and the adjacent intersection vector, specifically comprising:

[0014] Extract the number of trajectory points before the corresponding trajectory point of the first intersection and generate the forward vector;

[0015] Obtain the set of adjacent intersections of the first intersection and generate the first vector pointing from the first intersection to each adjacent intersection;

[0016] Calculate the angle between the front vector and each head vector, and select the adjacent intersection direction with the smallest angle as the entrance direction.

[0017] By matching the angle between the forward vector generated by the trajectory points and the vector of the adjacent intersection, errors caused by incomplete intersection data are avoided, the accuracy of the first intersection entrance direction identification is ensured, and a reliable basis is provided for subsequent flow direction judgment.

[0018] Preferably, the step of determining the exit direction at the tail intersection by matching the angle between the backward trajectory vector and the vector of the adjacent intersection specifically includes:

[0019] Extract the number of trajectory points after the corresponding trajectory point of the end intersection and generate the back vector;

[0020] Obtain the set of adjacent intersections of the tail intersection and generate a tail vector pointing from the tail intersection to each adjacent intersection;

[0021] Calculate the angle between the rear vector and each tail vector, and select the adjacent intersection direction with the smallest angle as the exit direction.

[0022] By calculating the angle between the rear vector and the vector of the adjacent intersection, the uncertainty of the exit direction of the tail intersection is effectively handled, data errors are compatible, flow direction misjudgment caused by the lack of adjacent relationships is prevented, and system stability is improved.

[0023] Preferably, the dividing of the angle ranges of each driving direction according to the entrance direction angle specifically includes: calculating the left turn angle range, the straight go angle range, the right turn angle range and the U-turn angle range according to the intersection entrance angle, and adjusting all angle ranges to the 0°-360° range.

[0024] Preferably, the matching of the exit direction angle with the angle range to determine the driving direction specifically includes:

[0025] Prioritize straight flow. If the exit angle falls within the straight flow range, the flow direction is straight flow.

[0026] The second priority is to judge right turn. If there is no match for straight driving and the exit angle falls within the right turn range, the flow direction is right turn;

[0027] Determine the left turn again. If there is no matching right turn and the exit angle falls within the left turn range, the flow direction is left turn;

[0028] Finally, the U-turn is judged. If there is no left turn matched and the exit angle falls within the U-turn range, the flow direction is a U-turn.

[0029] The priority order is used to match the flow direction, which complies with actual traffic rules and reduces the misjudgment rate. It improves the recognition efficiency, especially in complex intersection scenarios, and ensures the correctness of the priority release of special service vehicles.

[0030] Preferably, the flow direction verification of the identified lane flow attributes at the intersection entrance specifically includes:

[0031] If the flow direction is identified as straight, check whether the entrance lane has a straight attribute. If there is no straight lane, calculate the vector angle based on the number of trajectory points before the entrance and the number of trajectory points after the exit. If the angle is greater than 180°, correct it to straight, otherwise correct it to a left turn.

[0032] If the direction of flow is identified as a left turn, check whether the entrance lane has a left turn attribute. If there is no left turn lane, calculate the vector angle. If the angle is <180°, correct it to a straight ahead direction; otherwise, correct it to a right turn.

[0033] If the flow direction is identified as a right turn, check whether the import lane has a right turn attribute; if there is no right turn lane, calculate the vector angle. If the angle is <180°, correct it to a left turn, otherwise correct it to a straight go.

[0034] The dual mechanisms of lane attribute verification and vector angle correction solve the problem of program misjudgment. When lane attributes are missing or mismatched, the flow direction is dynamically adjusted based on trajectory point data, significantly enhancing the reliability and adaptability of flow direction recognition.

[0035] Preferably, in the process of matching the exit direction angle with the angle range to determine the driving direction, when the exit and exit directions cannot be matched, a certain number of trajectory points before the current intersection are extracted to generate an entry vector, and the angle between the vector and the due east direction is calculated as the entry angle; a certain number of trajectory points after the current intersection are extracted to generate an exit vector, and the angle between the vector and the due east direction is calculated as the exit angle.

[0036] When the adjacent relationship data is incomplete, an alternative solution based on trajectory points is provided to directly calculate the entry and exit angles, ensuring that the system is compatible with various data error scenarios, avoiding recognition interruptions, and improving the fault tolerance of the overall method.

[0037] Preferably, the vector angle is calculated by combining a vector cross product and a dot product to determine a clockwise angle value.

[0038] Preferably, the numbering of the track points in the driving order specifically includes: breaking up the track points after processing the navigation track points, with the distance between each two adjacent track points being less than or equal to 35 meters, and numbering them in the driving order.

[0039] This ensures that the trajectory points have a moderate density and are numbered in order, which facilitates subsequent intersection matching and vector generation, improves the processing efficiency and matching accuracy of trajectory data, and reduces recognition omissions caused by trajectory sparsity.

[0040] Preferably, the left turn angle range is the entrance angle +45° to +135°; the straight-ahead angle range is the entrance angle +135° to +225°; the right turn angle range is the entrance angle +225° to +315°; and the U-turn angle range is the entrance angle -45° to +45°.

[0041] Compared with the prior art, the present invention has the following beneficial effects.

[0042] 1. This invention significantly improves the efficiency of special service missions through dynamic route adaptation. It supports generating navigation routes by arbitrarily selecting starting and ending points, and automatically identifies the entrance direction and vehicle flow direction of intersections, completely replacing the traditional manual calibration method. This not only significantly shortens route creation and review time, but also enables real-time and flexible adjustments to special service vehicle routes, effectively ensuring rapid response capabilities for emergency missions.

[0043] 2. This invention uses a dual verification mechanism to enhance the accuracy of flow direction recognition. First, it intelligently divides the flow direction range and performs priority matching based on the entrance and exit angles to preliminarily determine the turn type. Then, it conducts a secondary review based on lane attribute data. When the recognition result conflicts with the lane function, the flow direction is dynamically corrected based on the angle between the trajectory point vectors. This process significantly reduces the program's misjudgment rate and improves the reliability of priority passage instructions.

[0044] 3. This invention boasts excellent fault tolerance and data compatibility. When intersection adjacency relationships are missing or data errors occur, it can directly generate entrance and exit vector angles based on trajectory points to determine flow direction. Furthermore, through the dual safeguards of lane attribute verification and vector angle correction, it resolves recognition interruptions caused by incomplete basic information, ensuring that the system can still stably output effective priority instructions in complex road network environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The present invention is an overall flow chart of an embodiment of a method for identifying flow direction at an intersection entrance with priority passage on escorted routes.

[0046] Figure 2The present invention provides a flow chart of a method for identifying the entrance flow direction of an intersection with priority passage on escorted routes, which calculates the entrance direction and exit direction of each intersection in an intersection sequence.

[0047] Figure 3 This is a flow chart of determining the driving direction by angle matching in a method for identifying the flow direction at an intersection entrance with priority passage on escorted routes according to the present invention.

[0048] Figure 4 The present invention provides a flow chart of a secondary verification of flow direction in a method for identifying flow direction at an intersection entrance with priority passage on escorted routes.

[0049] Figure 5 This is a detailed flow chart of the calculation of the angle range of each flow direction based on the entrance angle of a method for identifying the entrance flow direction of an intersection with priority passage on escorted routes of the present invention. DETAILED DESCRIPTION

[0050] To make the objectives, technical solutions, and advantages of the present disclosure more apparent, embodiments of the present disclosure are described in further detail below with reference to the accompanying drawings. The proportions of the components herein are not drawn to scale, and the proportions and dimensions shown in the accompanying drawings are not intended to limit the essential technical solutions of the present disclosure. These embodiments do not describe all details in detail, nor do they limit the present disclosure to the specific embodiments described.

[0051] See also Figure 1-5 As shown, a method for identifying the flow direction at an intersection entrance with priority passage on a escort route includes:

[0052] Obtain navigation route trajectory data and number the trajectory points in sequence; match the intersections along the trajectory based on the intersection latitude and longitude information to generate a sequence of intersections arranged in sequence;

[0053] Based on the intersection adjacent relationship data, the first intersection determines the entrance direction by matching the angle between the forward trajectory vector and the vector of the adjacent intersection. The last intersection determines the exit direction by matching the angle between the backward trajectory vector and the vector of the adjacent intersection. The middle intersection determines the entrance and exit directions based on the relationship between adjacent intersections.

[0054] The driving direction is divided into angle ranges according to the entrance direction angle, and the exit direction angle is matched with the angle range to determine the driving direction; the identified flow direction is verified in combination with the lane flow attributes at the intersection entrance, and the flow direction information is output.

[0055] The present invention first calls the AutoNavi API interface when a special service vehicle navigation task is initiated, and pre-processes the returned navigation route trajectory data; secondly, based on the point information with longitude and latitude at the intersection, all intersections along the navigation route trajectory are matched; furthermore, based on the intersection adjacent relationship data, the upstream and downstream directions between two adjacent intersections along the trajectory are matched, and the first and last intersections along the trajectory are processed and matched separately, that is, the entry and exit directions of all intersections along the trajectory are obtained; finally, according to the angles of the entry and exit directions, when entering the intersection at the entry angle, different flow direction angle ranges of left turn, straight going, right turn, and U-turn are divided, and according to the exit angle, it is determined which flow direction angle range it falls into, so that the entrance and flow direction information at the current intersection can be automatically identified, and according to the lane attributes at the intersection entrance, a secondary judgment is made as to whether the identified flow direction is reasonable, and finally the intersection entrance and flow direction information is obtained.

[0056] Specifically, it includes:

[0057] Identify the entrances and exits of all intersections along the route based on the path and intersection adjacency: Match all intersections along the route based on the intersection's latitude and longitude points. Furthermore, match the upstream and downstream directions between two adjacent intersections along the route based on the intersection adjacency data. Separately process and match the first and last intersections along the route to obtain the entry and exit directions of all intersections along the route.

[0058] Identify flow direction based on entrance and exit angles: Based on the entrance and exit angles, the system can automatically identify the entrance and flow direction information at the current intersection by determining the flow angle range for left turn, straight ahead, right turn, and U-turn when entering the intersection from the entrance angle.

[0059] Secondary review of whether the flow direction is reasonable and correction based on the attributes of the entrance lane: Based on the attributes of the lane at the intersection entrance, secondary judgment is made on whether the recognized flow direction is reasonable, and finally the intersection entrance and flow direction information is obtained.

[0060] like Figure 1 In one embodiment shown, Figure 1 This is a flowchart of an embodiment of a method for identifying flow direction at intersection entrances with priority access on escorted routes. First, the system acquires the vehicle's navigation route trajectory data and numbers the trajectory points in order of travel. When processing the trajectory points, they are broken up to ensure that the distance between any two adjacent trajectory points is less than or equal to 35 meters. Then, based on the intersection's longitude and latitude information, the system matches all intersections along the trajectory's path, generating a sequentially arranged intersection sequence.

[0061] Next, the system determines the entrance and exit directions of each intersection in the sequence. For the first intersection in the sequence (the first intersection), the system extracts the number of trajectory points preceding the corresponding trajectory point of the first intersection and generates a vector pointing to the first intersection (the preceding vector). It then obtains the set of adjacent intersections of the first intersection and generates vectors pointing from the first intersection to each of the adjacent intersections (the first vector).

[0062] Subsequently, the angle between the front vector and each head vector is calculated, and the direction of the adjacent intersection with the smallest angle is selected as the entrance direction of the first intersection. For the last intersection (tail intersection) in the sequence: the system extracts the number of trajectory points after the trajectory point corresponding to the tail intersection, and generates a vector (back vector) pointing from the tail intersection to this point; then, the set of adjacent intersections of the tail intersection is obtained, and vectors (tail vectors) pointing from the tail intersection to each adjacent intersection are generated; then, the angle between the back vector and each tail vector is calculated, and the direction of the adjacent intersection with the smallest angle is selected as the exit direction of the tail intersection. For each intersection in the middle of the sequence, its entrance and exit directions are determined directly based on the known intersection adjacent relationship data.

[0063] Next, the vehicle flow direction at each intersection is determined based on the entrance angle. Based on the current intersection entrance angle, the system calculates the left turn angle range (+45° to +135°), the straight-ahead angle range (+135° to +225°), the right turn angle range (+225° to +315°), and the U-turn angle range (-45° to +45°), adjusting these angle ranges to fall within the 0°-360° range. The system then matches the previously determined exit angle with these defined angle ranges to determine the flow direction.

[0064] The matching rules are as follows:

[0065] The system prioritizes determining whether a vehicle is going straight. If the exit angle falls within the straight-line range, the direction is straight. If a straight-line direction is not matched, the system prioritizes determining a right turn. If the exit angle falls within the right-turn range, the direction is right. If a right turn is still not matched, the system then determines whether a vehicle is going left. If the exit angle falls within the left-turn range, the direction is left. Finally, the system determines whether a vehicle is going U-turn. If a left turn is still not matched and the exit angle falls within the U-turn range, the direction is U-turn. (Note: If the intersection adjacency relationship cannot be used to match the inlet and outlet directions, the system will extract a certain number of trajectory points before the current intersection to generate the inlet vector and calculate the angle between it and the due east direction as the inlet angle. It will also extract a certain number of trajectory points after the current intersection to generate the outlet vector and calculate the angle between it and the due east direction as the outlet angle before performing the above matching.)

[0066] Finally, the system verifies and corrects the previously identified driving direction based on the actual lane flow attributes at the intersection entrance:

[0067] If the flow direction is identified as straight, check whether the import lane contains the straight attribute;

[0068] If there is no through lane, the system calculates the vector angle between the two trajectory points based on a certain number of trajectory points before the entrance and a certain number of trajectory points after the exit (the vector angle is calculated by combining the vector cross product and dot product to determine the clockwise angle value). If the angle is greater than 180°, the vehicle is corrected to go straight, otherwise it is corrected to turn left.

[0069] If the flow direction is identified as a left turn, check whether the import lane contains a left turn attribute;

[0070] If there is no left-turn lane, the vector angle is calculated based on the same method. If the angle is less than 180°, it is corrected to go straight, otherwise it is corrected to turn right.

[0071] If the flow direction is identified as a right turn, it is checked whether the import lane contains a right turn attribute; if there is no right turn lane, the vector angle is calculated based on the same method. If the angle is less than 180°, it is corrected to a left turn, otherwise it is corrected to a straight go.

[0072] After completing all the above steps, the system outputs the final confirmed intersection entrance flow direction information.

[0073] The proposed method for identifying traffic flow direction at intersection entrances during escort route priority passage pioneers solutions to the core pain points of traditional special service vehicle signal priority systems, including cumbersome manual calibration, inadequate traffic flow identification, and poor fault tolerance. Through intelligent dynamic route adaptation and a dual verification mechanism, it significantly improves the efficiency and system reliability of emergency vehicles.

[0074] First, the system achieves dynamic planning and key parameter identification of special service routes in a fully automated manner. It uses the navigation service interface to obtain real-time trajectory data, performs high-precision density processing and sequential numbering of trajectory points, and automatically matches and generates an ordered intersection sequence in combination with the longitude and latitude information of the intersection. This process completely replaces the traditional model that relies on manual marking of entrance directions and turning directions at each intersection, supports flexible route planning with arbitrary starting and ending points, and reduces route configuration time from hours to minutes. More importantly, when a vehicle needs to detour due to sudden road conditions or the mission objectives are temporarily changed, the system can instantly reconstruct priority instructions based on the new trajectory, overcoming the fundamental defect of the rigidity and failure of traditional preset routes.

[0075] Secondly, the method innovatively establishes a multi-level intelligent flow direction judgment and verification system. In view of the special location characteristics of the head-to-tail intersection, the system uses the angle matching strategy of the forward and backward trajectory vectors and the adjacent intersection vectors to accurately calculate the entry and exit directions; at the intermediate intersection, the adjacent relationship data is directly called to efficiently determine the flow direction. More importantly, the flow direction recognition process sets a strict priority logic based on traffic rules: the straight flow direction is judged first, and right turns, left turns and U-turns are matched in turn, and the entrance angle is scientifically divided into four non-overlapping turning fan-shaped areas. This orderly matching mechanism based on the angle range effectively reduces the risk of misjudgment in complex intersection environments.

[0076] To ensure absolute reliability of the recognition results, the system introduces a dual verification process for lane attribute data and trajectory point vectors. When the initially determined turning type does not match the actual function of the lane, the system automatically triggers the vector angle correction algorithm: extracting key trajectory points before and after the entrance to generate vectors, calculating the clockwise angle through cross products and dot products, and dynamically correcting the flow direction based on the preset threshold. For example, if the straight-ahead judgment encounters a situation where the lane does not have a straight-ahead function, the system intelligently corrects it to straight ahead or turn left based on whether the angle is greater than the threshold. This design fundamentally solves the flow direction conflicts caused by changes in lane functions or data errors due to road network reconstruction.

[0077] Finally, the method demonstrates excellent fault tolerance and data compatibility. When intersection adjacency data is missing, the system can be downgraded to pure trajectory vector analysis mode, directly generating entry and exit vectors based on trajectory points and calculating angles based on the east direction. This ensures stable and effective command output even when basic information is incomplete. Furthermore, by standardizing angles to a circular range and combining lane attribute verification, the system can handle complex scenarios such as newly added ramps and irregular intersections in urban road networks, significantly improving its universality.

[0078] This invention fundamentally reshapes the execution logic of the special service priority mechanism. Its application will significantly reduce the amount of time vehicles spend waiting at intersections, avoid secondary congestion caused by false signal triggering, and gain a critical window of time for emergency rescue. Consequently, traffic management departments can use this technology to establish a highly reliable automated priority system, ultimately boosting the effectiveness of the entire city's emergency response system.

[0079] Reference Figures 2 to 5 In one embodiment, wherein, Figure 2 The present invention provides a flow chart of a method for identifying the entrance flow direction of an intersection with priority passage on escorted routes, which calculates the entrance direction and exit direction of each intersection in an intersection sequence. Figure 3 This is a flow chart of determining the driving direction by angle matching in a method for identifying the flow direction at an intersection entrance with priority passage on escorted routes according to the present invention. Figure 4The present invention provides a flow chart of a secondary verification of flow direction in a method for identifying flow direction at an intersection entrance with priority passage on escorted routes. Figure 5 This is a detailed flow chart of the method for identifying the flow direction at the entrance of an intersection with priority passage on escorted routes, which calculates the range of flow direction angles based on the entrance angle. The present invention is carried out in the following manner:

[0080] Step 1:

[0081] Known navigation trajectory points, intersection ID, longitude and latitude; intersection entrance angles and lane flow information, and intersection adjacent relationship information.

[0082] Step 2:

[0083] Process the navigation track points, break them up, make sure the distance between any two adjacent track points is less than or equal to 35 meters, and number them sequentially.

[0084] Step 3:

[0085] The intersection ID is matched to the nearest track point according to the longitude and latitude, and the track number is attached to obtain an ordered intersection sequence list.

[0086] Step 4:

[0087] Process the intersection sequence table, extract the previous intersection of each intersection, and match the entrance and exit directions of adjacent intersections for the intersection sequence table based on the intersection adjacency relationship.

[0088] Step 5:

[0089] For the first intersection A' in the intersection sequence, calculate its entrance direction and upstream virtual intersection ID:

[0090] 5.1 Get the latitude and longitude B' of the third point before the trajectory number corresponding to A', and construct a vector A'B' with intersection A' as the starting point and B' as the end point;

[0091] 5.2 Call the adjacent intersection interface to obtain the adjacent intersection ID, then call the intersection interface based on the ID to obtain the intersection latitude and longitude, and generate a vector set A'C' with intersection A' as the starting point and the adjacent intersection as the end point;

[0092] 5.3 Calculate the angle between vector A'B' and vector set A'C', and select the one with the closest angle difference. If there are two closest ones, select only one.

[0093] 5.4 Output the first intersection entrance direction, including "adjacent entrance direction ID", "adjacent intersection ID", "entrance direction ID", "intersection ID (A')", and "angle difference".

[0094] Step 6:

[0095] For the last intersection A'' in the intersection sequence, calculate its entrance direction and downstream virtual intersection ID:

[0096] 6.1 Get the latitude and longitude B'' of the third point after the track number corresponding to A'', and construct the vector A''B'' with the intersection A'' as the starting point and B'' as the end point

[0097] 6.2 Call the adjacent intersection interface to obtain the adjacent intersection ID, then call the intersection interface based on the ID to obtain the intersection latitude and longitude, and generate a vector set A''C'' with intersection A'' as the starting point and the adjacent intersection latitude and longitude as the end point;

[0098] 6.3 Calculate the angle between vector A''B'' and vector set A''C'', and select the one with the closest angle difference. If there are two closest ones, select only one.

[0099] 6.4 Output the last intersection entrance direction and the previous intersection exit direction, including "adjacent entrance direction ID", "adjacent intersection ID", "entry direction ID", "intersection ID (A')", and "angle difference".

[0100] Step 7:

[0101] According to the inlet and outlet directions and the entrance angles of the intersection, the entrance angle and exit angle of the intersection are identified.

[0102] Step 8:

[0103] When the entrance and exit angles cannot be calculated successfully, the third point C1 of the trajectory before the intersection C0 is extracted, about 50 meters away, and the angle between the vector C0C1 and the east direction is calculated as the entrance angle into the intersection;

[0104] Extract the third point C2 of the trajectory after passing through the intersection C0, about 50 meters away, and calculate the angle between the vector C0C2 and the east direction as the exit angle of the exit.

[0105] Step 9:

[0106] According to the intersection entrance angle calculation, if you enter from the entrance and turn left, the angle range calculation process for turning left, going straight, turning right, and turning around is as follows:

[0107] 9.1 Calculating the left turn angle range

[0108] a_left = in_degree + 45° (starting angle of left turn)

[0109] b_left = in_degree + 135° (the ending angle of the left turn);

[0110] 9.2 Calculating the straight-ahead angle range

[0111] a_straight = in_degree + 135° (straight start angle)

[0112] b_straight = in_degree + 225° (the end angle of the straight line);

[0113] 9.3 Calculating the right turn angle range

[0114] a_right = in_degree + 225° (the angle at which the right turn begins)

[0115] b_right = in_degree + 315° (right turn end angle);

[0116] 9.4 Calculating U-turn Angle Range

[0117] a_turn_back = in_degree - 45° (the angle at which the U-turn begins)

[0118] b_turn_back = in_degree + 45° (the end angle of the U-turn);

[0119] 9.5 Adjusting the Angle

[0120] Call the adjust_angle method to adjust all angle values ​​to ensure they are between 0° and 360°.

[0121] Step 10:

[0122] According to the intersection exit angle calculation, if you enter from the entrance and turn left, the angle range calculation process for turning left, going straight, turning right, and turning around is as follows:

[0123] 1: Prioritize straight ahead

[0124] If a_straight is less than b_straight, then check if out_degree is in the range [a_straight, b_straight],

[0125] If the exit angle is within the range, return 2, indicating straight ahead.

[0126] Otherwise, if a_straight is greater than b_straight, check if the exit angle is greater than or equal to a_straight or less than or equal to b_straight;

[0127] If the exit angle meets the conditions, return 2, indicating straight ahead.

[0128] 2: Next, determine whether to turn right

[0129] If a_right is less than b_right, check if out_degree is in the range [a_right, b_right],

[0130] If the exit angle is within the range, return 3, indicating a right turn.

[0131] Otherwise, if a_right is greater than b_right, check if the exit angle is greater than or equal to a_right or less than or equal to b_right;

[0132] If the exit angle meets the conditions, return 3, indicating a right turn.

[0133] 3: Then judge to turn left

[0134] If a_left is less than b_left, check if the exit angle is in the range [a_left, b_left],

[0135] If the exit angle is within the range, return 1, indicating a left turn.

[0136] Otherwise, if a_left is greater than b_left, check if the exit angle is greater than or equal to a_left or less than or equal to b_left;

[0137] If the exit angle meets the conditions, it returns 1, indicating a left turn.

[0138] 4: Final judgment of U-turn

[0139] If a_turn_back is less than b_turn_back, check if the exit angle is within the range [a_turn_back, b_turn_back],

[0140] If the exit angle is within the range, it returns 8, indicating a U-turn.

[0141] Otherwise, if a_turn_back is greater than b_turn_back, check if the exit angle is greater than or equal to a_turn_back or less than or equal to b_turn_back;

[0142] If the exit angle meets the conditions, the function returns 8, indicating a U-turn.

[0143] 5: If no type is matched, return 0

[0144] If the exit angle does not match any type, it returns 0, indicating an unknown type.

[0145] Step 11:

[0146] Check the lane flow attributes at the intersection entrance to see if the flow direction is correct:

[0147] If it is identified as going straight at the entrance of the intersection, check whether there is a lane with straight-line attributes such as going straight, straight right, or straight left in the direction of the entrance of the intersection. If so, the straight-line judgment is normal.

[0148] If there is no straight lane attribute, but there are left-turn and right-turn lanes, extract the third point C1 of the trajectory point before the intersection C0, about 50 meters away, as the entrance angle into the intersection, and extract the third point C2 of the trajectory point after the intersection C0, about 50 meters away.

[0149] Calculate the angle between the two vectors, starting from vector C0C1 and ending in clockwise direction with vector C0C2. If the angle is less than 180 degrees, turn left; if it is greater than 180 degrees, go straight.

[0150] If a left turn is identified at the entrance of the intersection, check whether there is a lane with left-turn attributes such as left turn or straight left in the direction of the entrance of the intersection. If so, the left turn is judged to be normal.

[0151] If there is no left-turn lane attribute, but there are straight and right-turn lanes, extract the third point C1 of the trajectory point before the intersection C0, about 50 meters away, as the entrance angle into the intersection, and extract the third point C2 of the trajectory point after the intersection C0, about 50 meters away.

[0152] Calculate the vector angle starting from vector C0C1 and ending in clockwise direction with vector C0C2. If the angle is less than 180 degrees, go straight. If it is greater than 180 degrees, turn right.

[0153] If a right turn is identified at the entrance of the intersection, check whether there is a lane with right-turn attributes such as a right turn or a right straight in the direction of the entrance of the intersection. If so, the right turn is judged to be normal.

[0154] If there is no right-turn lane attribute, but there are straight and left-turn lanes, extract the third point C1 of the trajectory point before the intersection C0, about 50 meters away, as the entrance angle into the intersection, and extract the third point C2 of the trajectory point after the intersection C0, about 50 meters away.

[0155] Calculate the angle between the two vectors, starting from vector C0C1 and ending in clockwise direction with vector C0C2. If the angle is less than 180 degrees, turn left; if it is greater than 180 degrees, go straight.

[0156] Step 12:

[0157] Finally, the entrance direction of each intersection and the flow direction when entering can be output as left turn, straight ahead, right turn, or U-turn.

[0158] The advantage of this invention is that special service routes can arbitrarily select their starting and ending points. After confirmation, the route automatically identifies the intersections, their entrances, and flow directions, reducing manual creation and review time. It also addresses programmatic flow direction misjudgments, provides secondary evidence of lane flow direction, and increases flow reliability. It also addresses incomplete relationships between adjacent intersections by automatically identifying entrances and flow directions based on the entrance and exit angles of the navigation trajectory. This provides superior compatibility with data errors that prevent accurate entrance and flow direction information from being provided.

[0159] The present invention is not limited to the above-mentioned embodiments. Regardless of any changes in shape or material composition, any structural design provided by the present invention is a variation of the present invention and should be considered within the scope of protection of the present invention.

Claims

1. A method for identifying the flow direction at an intersection entrance with priority passage on escorted routes, characterized in that: include: Obtain navigation route trajectory data and number the trajectory points in sequence; Match the intersections along the trajectory based on the intersection latitude and longitude information to generate an intersection sequence arranged in order; Based on the intersection adjacent relationship data, the entrance direction of the first intersection is determined by matching the angle between the forward trajectory vector and the vector of the adjacent intersection. The exit direction of the last intersection is determined by matching the angle between the backward trajectory vector and the vector of the adjacent intersection. Specifically, the following steps are performed: extracting a certain number of trajectory points before or after the corresponding trajectory point of the intersection, generating a vector pointing to the intersection, obtaining a set of adjacent intersections of the intersection, generating vectors pointing from the intersection to each adjacent intersection, calculating the angle between the vectors, and selecting the adjacent intersection direction with the smallest angle as the entrance and exit directions. The exit and entry directions of the intermediate intersection are determined by the relationship between adjacent intersections. The driving direction is divided into angle ranges according to the import direction angle, and the export direction angle is matched with the angle range to determine the driving direction. The identified flow direction is verified in combination with the lane flow attribute at the intersection entrance. Specifically, the flow direction is identified and verified whether the import lane contains the flow attribute. If not, the intersection is used as the starting point, and the vector angle is calculated based on the number of trajectory points before the import and the number of trajectory points after the exit. The flow direction is corrected according to the vector angle and the flow direction information is output.

2. A method for identifying the flow direction at an intersection entrance with priority passage on a escorted route according to claim 1, characterized in that: The first intersection determines the entrance direction by matching the angle between the forward trajectory vector and the adjacent intersection vector: Extract the number of trajectory points before the trajectory point corresponding to the first intersection and generate a forward vector pointing to the first intersection; Obtain the set of adjacent intersections of the first intersection and generate the first vector pointing from the first intersection to each adjacent intersection; Calculate the angle between the front vector and each head vector, and select the adjacent intersection direction with the smallest angle as the entrance direction.

3. A method for identifying the flow direction at an intersection entrance with priority passage on a escorted route according to claim 1 or 2, characterized in that: The method of determining the exit direction by matching the angle between the backward trajectory vector and the adjacent intersection vector at the tail intersection specifically includes: Extract the number of trajectory points after the trajectory point corresponding to the end intersection and generate a back vector pointing to the end intersection; Obtain the set of adjacent intersections of the tail intersection and generate a tail vector pointing from the tail intersection to each adjacent intersection; Calculate the angle between the rear vector and each tail vector, and select the adjacent intersection direction with the smallest angle as the exit direction.

4. A method for identifying flow direction at an intersection entrance with priority passage on escorted routes according to claim 3, characterized in that: The dividing of the angle ranges of each driving direction according to the entrance direction angle specifically includes: calculating the left turn angle range, the straight angle range, the right turn angle range and the U-turn angle range according to the intersection entrance angle, and adjusting all angle ranges to the 0°-360° range.

5. The method for identifying the flow direction at an intersection entrance with priority passage on a escorted route according to claim 4, characterized in that: The method of matching the exit direction angle with the angle range to determine the driving direction specifically includes: Prioritize straight flow. If the exit angle falls within the straight flow range, the flow direction is straight flow. The second priority is to judge right turn. If there is no match for straight driving and the exit angle falls within the right turn range, the flow direction is right turn; Determine the left turn again. If there is no matching right turn and the exit angle falls within the left turn range, the flow direction is left turn; Finally, the U-turn is judged. If there is no left turn matched and the exit angle falls within the U-turn range, the flow direction is a U-turn.

6. The method for identifying the flow direction at an intersection entrance with priority passage on a escorted route according to claim 5, characterized in that: The correction of the flow direction according to the vector angle specifically includes: If the flow direction is identified as straight, check whether the entrance lane has a straight attribute. If there is no straight lane, calculate the vector angle based on the number of trajectory points before the entrance and the number of trajectory points after the exit, starting from the intersection. If the angle is greater than 180°, correct it to straight, otherwise correct it to a left turn. If the direction of the traffic flow is identified as a left turn, check whether the entrance lane has a left-turn attribute. If there is no left-turn lane, calculate the vector angle starting from the intersection. If the angle is less than 180°, correct it to a straight ahead direction; otherwise, correct it to a right turn. If the direction of flow is identified as a right turn, check whether the import lane has a right-turn attribute; if there is no right-turn lane, calculate the vector angle with the intersection as the starting point. If the angle is <180°, correct it to a left turn, otherwise correct it to a straight ahead.

7. A method for identifying flow direction at an intersection entrance with priority passage on a escorted route according to claim 5 or 6, characterized in that: In the process of matching the exit direction angle with the angle range to determine the driving direction, when the exit and exit directions cannot be matched, a certain number of trajectory points before the current intersection are extracted to generate an entry vector with the intersection as the starting point, and the angle between the entry vector and the due east direction is calculated as the entry angle; a certain number of trajectory points after the current intersection are extracted to generate an exit vector with the intersection as the starting point, and the angle between the exit vector and the due east direction is calculated as the exit angle.

8. The method for identifying the flow direction at an intersection entrance with priority passage on a escorted route according to claim 6, characterized in that: The vector angle is calculated by combining the vector cross product and the dot product to determine the clockwise angle value.

9. The method for identifying the flow direction at an intersection entrance with priority passage on a escorted route according to claim 1, characterized in that: The numbering of the track points in the driving order specifically includes: breaking up the track points after processing the navigation track points, so that the distance between each two adjacent track points is less than or equal to 35 meters, and numbering them in the driving order.

10. The method for identifying the flow direction at an intersection entrance with priority passage on a escorted route according to claim 4, characterized in that: The left turn angle range is the entrance angle +45° to +135°; the straight-ahead angle range is the entrance angle +135° to +225°; the right turn angle range is the entrance angle +225° to +315°; and the U-turn angle range is the entrance angle -45° to +45°.

Images