Positioning coordinate conversion system and method suitable for unmanned formation
By employing oblique Mercator projection and master-slave node collaborative calibration, the problems of trajectory jumps and long-distance distortion in unmanned formations were solved, achieving positioning accuracy and reliability for long-distance unmanned formations and adapting to various scenario requirements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-15
- Publication Date
- 2026-03-27
AI Technical Summary
Existing unmanned platooning positioning technology suffers from issues such as trajectory jumps, long-distance distortion, and inconsistent coordinate systems during long-distance driving, failing to meet the positioning requirements of truck trunk transportation and lacking sufficient platooning collaborative positioning capabilities.
The method of combining oblique Mercator projection with master-slave node collaborative calibration is adopted. The initial GNSS latitude and longitude of the formation master node is used as the reference point. The tilt angle of the projection surface is set to match the driving route to achieve accurate positioning in local areas. The collaborative calibration of the reference point within the formation is completed through vehicle-to-vehicle communication. The master-slave node collaborative calibration mechanism is designed to ensure that long-distance distortion is controllable.
It achieves continuous positioning of long-distance unmanned platoons, controls long-distance distortion, ensures collaborative perception and control of vehicles within the platoon, adapts to various scenario requirements, including short-distance urban and long-distance trunk roads, and does not require frequent switching of UTM bands, thus improving positioning accuracy and reliability.
Smart Images
Figure CN121751083A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the interdisciplinary fields of autonomous driving, geographic information engineering, and vehicle-to-everything (V2X) collaborative control, and more specifically, to a positioning coordinate transformation system and method suitable for autonomous driving formations. Background Technology
[0002] In the field of autonomous driving positioning technology, converting the latitude and longitude (geocentric coordinate system) acquired by GNSS into a Cartesian coordinate system (such as the ENU East-North-Sky coordinate system) for easier calculation is a core prerequisite for path planning, vehicle control, and cooperative perception. Existing technologies mainly employ two schemes to achieve coordinate transformation: "UTM area projection" and "UTM area locking," as detailed below: The coordinate transformation scheme based on UTM region switching is as follows: UTM (Universal Transverse Mercator) projection is currently the most commonly used coordinate transformation technology in the field of autonomous driving. Essentially, it is a variant of the Gauss-Kruger projection, dividing the Earth into 60 projection zones (each zone representing 6° of longitude). Within each projection zone, a planar coordinate system is unfolded with the central meridian as the reference. System components: Hardware includes: a GNSS module (supporting GPS / BeiDou dual-mode, positioning accuracy ≤1.5m), an onboard processor (such as ARM Cortex-A76, supporting real-time projection calculation), and a storage unit (storing UTM projection zone parameter tables); Software includes: a UTM projection algorithm module (implementing latitude and longitude to UTM planar coordinate transformation), a region determination module (real-time calculation of the UTM projection zone to which the current latitude and longitude belongs), and a reference point switching module (updating projection reference parameters when crossing zones). The workflow includes: the onboard GNSS module acquires the vehicle's latitude and longitude data in real time (sampling frequency 10Hz); the region determination module refers to the UTM projection zone parameter table to determine the current UTM zone to which the vehicle belongs (e.g., 114°-120°E belongs to zone 50); the UTM projection algorithm module uses the central meridian of the current UTM zone as a reference to convert latitude and longitude into planar coordinates (east X, north Y), and maps them to the East-North-Up (ENU) coordinate system; when the vehicle travels to the boundary of the UTM zone (e.g., from zone 50 to zone 51), the reference point switching module automatically updates the central meridian parameters and recalculates the ENU coordinates. Application scenarios: Primarily suitable for short-to-medium distance autonomous driving (e.g., urban delivery, park shuttle), scenarios requiring frequent crossings of UTM zones but with short single crossing distances.
[0003] The coordinate transformation scheme based on locking the UTM region is as follows: Addressing the "cross-zone reference switching" issue in Solution 1, this scheme optimizes the projection reference by using a "fixed projection reference": Upon system startup, the central meridian of the current UTM zone is selected as the unique reference. During subsequent travel, regardless of whether the vehicle crosses a UTM zone, the reference parameters are not updated, maintaining a fixed projection coordinate system. System composition: Based on Solution 1, the "regional judgment module" and "reference point switching module" are removed, and a "reference locking module" is added (stores the initial UTM zone central meridian parameters, preventing subsequent modification). The workflow is as follows: Upon initial GNSS latitude and longitude acquisition after system startup, the current UTM zone and its central meridian (e.g., 117°E) are determined, and this parameter is stored through the reference locking module. All subsequent latitude and longitude data are projected onto the UTM using this fixed central meridian as the reference, converting to ENU coordinates. Even if the vehicle crosses a UTM zone (e.g., moving from zone 50 to zone 51), the initial central meridian remains unchanged during projection. Application scenarios: Typically used in urban autonomous driving (such as Robotaxi), where the driving range is concentrated within a single UTM band (or the cross-band distance is ≤50km) and is not sensitive to long-distance distortion.
[0004] The existing solutions mentioned above are all based on the geographic information principle of "zonal projection." The initial design intention of UTM projection is to reduce distortion within a single area through "narrow-band projection" (distortion rate ≤0.1% per 6° longitude of each band). Related technical details can be found in the "Transverse Mercator Projection" chapter of *Principles of Geographic Information Systems* (3rd edition, by Wu Lun et al.), and the rules for dividing UTM projection zones in the industry standard *GB / T12892-2019 National Basic Scale Topographic Map Sheet Division and Numbering*. Neither of the existing solutions can meet the positioning requirements of long-distance unmanned platooning (such as truck long-haul transportation, single trip ≥1000km), and they suffer from core defects in platooning cooperative positioning, as follows: 1. Existing technical solution one has a drawback: when a vehicle crosses a UTM zone, solution one requires switching the central meridian reference, causing abrupt changes in the ENU coordinates of the same physical location before and after crossing the zone (e.g., at 120°E, the difference in X coordinates between the 50th and 51st zones can reach hundreds of meters). This abrupt change can cause the path planning algorithm of the autonomous driving system to misjudge the "location change" as abnormal, triggering emergency braking or path replanning, which seriously affects the continuity of long-distance transportation. At the same time, if vehicles in a platoon cross the zone one after another, the asynchronous switching of the reference will cause a temporary mismatch in the coordinate systems of each vehicle, making it impossible to drive in coordination.
[0005] 2. Existing technical solution two suffers from severe distortion over long distances: Although solution two avoids cross-zone jumps, the distortion rate of the UTM projection increases significantly with distance from the central meridian. When the vehicle is ≥200km away from the initial reference central meridian, the plane coordinate distortion rate rises from 0.1% to over 5% (e.g., if the initial reference is 117°E, and the vehicle travels to 130°E, the actual distance of 100km is displayed as 105km in the ENU coordinate system). For long-haul truck transportation (e.g., from Beijing to Guangzhou, spanning approximately 20° of longitude), this distortion leads to accumulated positioning errors, causing vehicles to deviate from the planned path and even causing positional discrepancies with other vehicles in the convoy.
[0006] 3. Both of the aforementioned existing technical solutions share a common deficiency: the lack of platooning cooperative positioning capability. Autonomous platooning requires all vehicles to achieve cooperative perception (e.g., sharing obstacle positions) and cooperative control (e.g., maintaining distance) within a unified coordinate system. However, in existing solutions, each vehicle independently calculates its ENU coordinates based on its initial position. (1) If the starting positions of the vehicles in the formation are different (e.g., the lead vehicle starts at point A and the following vehicle starts at point B, and the distance between A and B is ≥1km), then the reference points of the ENU coordinate system of each vehicle are different. The same physical target (e.g., the obstacle in front) will show a position difference of ≥1km in the ENU coordinates of different vehicles, and it is impossible to achieve perception data matching. (2) Even if the vehicles start at similar positions, the distortion difference in Scheme 2 after long-distance driving (the initial reference of each vehicle may be different) will cause the coordinate system deviation to gradually increase, eventually destroying the formation coordination.
[0007] (3) Limited application scenarios: Option 1 is only suitable for short-to-medium distance, frequent cross-belt scenarios, and Option 2 is only suitable for short-distance city-level scenarios. Neither can cover the truck trunk transportation needs of "long distance + platooning collaboration", and there are obvious scenario limitations.
[0008] Overcoming existing problems such as trajectory jumps, long-distance distortion, and inconsistencies in coordinate systems, improving local positioning accuracy and reliability, achieving collaborative calibration of intra-team reference points, and flexibly adapting to different scenarios are urgent technical issues that need to be addressed. Summary of the Invention
[0009] The purpose of this invention is to provide a positioning coordinate transformation system and method suitable for unmanned vehicle formations, which can improve the positioning accuracy and reliability of local areas, realize the collaborative calibration of reference points within the formation, and flexibly adapt to different scenarios.
[0010] This invention provides a positioning coordinate transformation system suitable for unmanned driving platoons, including an onboard sensing and computing terminal, a Mercator projection transformation unit, and a vehicle-to-vehicle cooperative control unit. The onboard sensing and computing terminal, the Mercator projection transformation unit, and the vehicle-to-vehicle cooperative control unit achieve data interaction through an onboard bus and a vehicle-to-vehicle communication network. The onboard sensing and computing terminal is used for global navigation satellite system data acquisition, projection calculation, and reference parameter storage. The Mercator projection transformation unit is used for coordinate transformation using the Mercator projection method with a specified reference point as the center. The vehicle-to-vehicle cooperative control unit is used for master-slave node identity management, reference point synchronization, and calibration process control within the platoon to ensure that all vehicle coordinate systems are consistent.
[0011] The present invention also provides a positioning coordinate transformation method for unmanned driving formations, which is applied to the above-mentioned positioning coordinate transformation system suitable for unmanned driving formations, and performs positioning coordinate transformation using the positioning coordinate transformation system suitable for unmanned driving formations.
[0012] Implementing the positioning coordinate transformation system and method suitable for unmanned vehicle formations provided by this invention has the following beneficial effects: This invention addresses the problems of trajectory jumps, long-distance distortion, and coordinate system inconsistencies in existing coordinate transformation schemes for long-distance unmanned platooning (such as truck long-haul transportation). It combines the principle of "concentrated relative positions of vehicles within an unmanned platoon" to... This paper proposes a solution based on the characteristics of "vehicle-to-vehicle communication capability" and "oblique Mercator local projection + master-slave node collaborative calibration". It achieves precise local positioning through oblique Mercator projection and completes collaborative calibration of reference points within the formation based on vehicle-to-vehicle communication. Specifically, it uses the initial GNSS latitude and longitude of the formation's master node as a reference point, sets the projection plane tilt angle to match the formation's driving route, and achieves calibration of the reference point's surrounding area. Distortion rate within range ENU coordinate transformation; design a master-slave node collaborative calibration mechanism for autonomous driving formations, including master-slave identity triggering conditions (lead vehicle as master, following vehicles as slaves), periodic communication message format (including reference latitude and longitude, calibration status field), and static verification logic (vehicle speed). And continue ) and calibration failure rollback mechanism; radial distance between master node detection and reference point When a stationary calibration reminder is triggered, the lead vehicle driver confirms and performs a benchmark update to ensure dynamic benchmark updates during long-distance driving with controllable distortion; at latitudes In the region, the standard Mercator projection is replaced with the oblique Mercator projection, while maintaining compatibility with the original collaborative calibration logic. This achieves a balance between simplified calculations and accuracy, enabling the implementation of the standard Mercator projection in low-latitude scenarios. By combining "heartbeat messages + calibration event messages," daily communication resource consumption is reduced, while ensuring reliable reception of calibration messages, thus optimizing event-driven vehicle-to-vehicle communication.
[0013] This invention eliminates the need to switch UTM belts, achieving continuous coordinate transformation based on oblique Mercator projection. It ensures continuity in long-distance transportation without trajectory jumps across any longitude range, thus resolving the trajectory jump problem. Furthermore, this invention leverages the fact that the distortion rate of oblique Mercator projection around the reference point is significantly lower than that of the locked UTM scheme, meeting the requirements for long-haul truck transportation. This invention addresses the positioning accuracy requirements of vehicles and controls long-distance distortion. Through master-slave node collaborative calibration, all vehicles share the same reference latitude and longitude, ensuring the accuracy of collaborative perception (such as obstacle location sharing) and collaborative control (such as maintaining vehicle distance), achieving a unified platoon coordinate system. This invention supports both single-vehicle mode (such as independent driving after a vehicle leaves the platoon) and multi-vehicle platoon mode, covering all scenarios of autonomous driving needs, including short-distance urban driving and long-distance trunk roads, and can flexibly adapt to various scenarios. The calibration failure rollback mechanism ensures that even if calibration is interrupted, the platoon can still drive normally based on the original reference, avoiding system paralysis. Static calibration further reduces position errors during coordinate updates, resulting in high reliability. Attached Figure Description
[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a block diagram of the positioning coordinate transformation system suitable for unmanned driving formations provided by the present invention; Figure 2 This is a flowchart of the positioning coordinate transformation method suitable for unmanned driving formations provided by the present invention. Detailed Implementation
[0015] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0016] Figure 1 A schematic diagram of a positioning coordinate transformation system suitable for unmanned vehicle formations according to this embodiment is shown. In this embodiment, the positioning coordinate transformation system suitable for unmanned vehicle formations includes: The system includes an in-vehicle sensing and computing terminal, a Mercator projection conversion unit, and a vehicle-to-vehicle cooperative control unit; the in-vehicle sensing and computing terminal, the Mercator projection conversion unit, and the vehicle-to-vehicle cooperative control unit achieve data interaction through an in-vehicle bus and a vehicle-to-vehicle communication network. The vehicle-mounted sensing and computing terminal is used for global navigation satellite system data acquisition, projection calculation, and reference parameter storage; The Mercator projection transformation unit is used to perform coordinate transformation using the Mercator projection method with a specified reference point as the center. The vehicle-to-vehicle cooperative control unit is used for managing the identity of master and slave nodes within the formation, synchronizing reference points, and controlling the calibration process to ensure that all vehicle coordinate systems are consistent.
[0017] In one exemplary embodiment, the vehicle-mounted sensing and computing terminal includes a GNSS module, a vehicle-mounted edge processor, a vehicle-mounted communication module, and a human-machine interaction unit. The GNSS module is used to acquire latitude and longitude, location accuracy, and velocity information. The vehicle-mounted edge processor is used for projection calculation, storage and updating of historical trajectory and map data; The vehicle-mounted communication module is used for direct communication, sending and / or receiving reference point data, master-slave identity information and calibration status; The human-computer interaction unit is used to output calibration status, calibration request, calibration result, and audio-visual reminders.
[0018] In one exemplary embodiment, the coordinate transformation process is as follows: The initial latitude and longitude of the formation master node are selected as the projection origin, and the initial latitude and longitude are used as the designated reference point for the East-North-Sky coordinates. Based on the specified reference point, convert the latitude and longitude of the target point into the target point's East-North-Sky coordinates.
[0019] In one exemplary embodiment, the process of converting the target point's latitude and longitude into its East-North-Sky coordinates is as follows: Calculate the spherical distance and azimuth between the target point's latitude and longitude and the specified reference point; Based on the equiangular characteristics of the oblique Mercator projection, the spherical distance is converted into a planar distance; The planar distance is decomposed into eastward and northward components, and the east-north-sky coordinates of the target point are obtained based on the eastward and northward components.
[0020] In one exemplary embodiment, the formulas for calculating the eastward and northward components are as follows: , , in, For the eastward component, For the northward component, The distance is the planar distance. It is the azimuth angle.
[0021] In one exemplary embodiment, the coordinate transformation method is the oblique Mercator projection method.
[0022] In one exemplary embodiment, the coordinate transformation method is the standard Mercator projection.
[0023] In one exemplary embodiment, the management of master and slave node identities within the formation includes: when a vehicle has not joined the formation, setting the vehicle as the master node; after a vehicle successfully joins the formation, if the vehicle is set as the navigator, then the vehicle is the master node; if the vehicle is not set as the navigator, then the vehicle is the slave node. The master node is used to store and broadcast the formation reference latitude and longitude, initiate the calibration process, check the calibration status of all slave nodes, determine whether the calibration is successful, and trigger the rollback mechanism. The slave nodes are used to receive the reference latitude and longitude broadcast by the master node, recalculate the historical trajectory, map data east-north-sky coordinates and other reference point update operations, and report the calibration progress and results to the master node.
[0024] In one exemplary embodiment, the communication messages of the vehicle-to-vehicle cooperative control unit are formatted using Protobuf encoding.
[0025] In one exemplary embodiment, the period of the communication message is .
[0026] In one exemplary embodiment, the communication messages of the vehicle-to-vehicle cooperative control unit include event messages, which include a node type field, a reference point latitude field, a reference point longitude field, a reference point synchronization status field, a current vehicle speed field, and a calibration result field.
[0027] In one exemplary embodiment, the communication message further includes a heartbeat message; the heartbeat message includes a node type field, a current vehicle speed field, and a calibration result field.
[0028] In one exemplary embodiment, the period of the heartbeat message is... .
[0029] In one exemplary embodiment, the process of controlling the reference point synchronization and calibration process includes: ① Calibration Trigger: The slave node sends an enqueue request to the master node. After the master node agrees, it broadcasts a calibration start message to all slave nodes. ② Static Verification: Based on the vehicle speeds of all slave nodes, confirm that all vehicles are stationary and for what duration. If a vehicle is not stationary, the master node will issue an audible and visual alarm. ③ Reference point synchronization: The master node broadcasts the master node's reference latitude and longitude; the slave node receives the master node's reference latitude and longitude and initiates a local update on the slave node: recalculate all location information related to the unfolded point, including historical trajectories and the East-North-Sky coordinate values of the prior high-precision map, and replace the coordinate data under the original reference. ④ Status Feedback: After the slave node completes the local update, it sets the reference point synchronization status of the slave node to false and the calibration result to pass, and feeds back the reference point synchronization status and calibration result to the master node. ⑤ Calibration Judgment: If the reference point synchronization status of all slave nodes is false and the calibration result is passed, the calibration is determined to be successful, the reference point synchronization status of the master node is set to false, and a "calibration completed" message is broadcast; if the calibration result of at least one slave node is failed, the master node rollback mechanism is triggered: all master nodes and slave nodes resume using the master node reference latitude and longitude before calibration, broadcast a calibration failure rollback to the original reference message, and retry after the vehicle stops again; ⑥ Confirm the radial distance between the current position of the master node and the reference point. And all vehicles are stationary for a period of time. The main node's human-computer interaction unit generates a calibration reminder, confirms the start of calibration, and returns to step ①.
[0030] In one exemplary embodiment, the process of synchronizing the reference point and controlling the calibration process further includes: starting the timer when calibration is initiated; if all slave nodes complete calibration within the calibration timeout threshold, the calibration is deemed successful; otherwise, all nodes trigger a rollback mechanism, the master node adopts the previous reference expansion point, and all slave nodes also adopt the previous master node's reference expansion point.
[0031] In one exemplary embodiment, the calibration timeout threshold is 10 seconds.
[0032] This embodiment provides a positioning coordinate transformation method suitable for unmanned driving formations, which is applied to the above-mentioned positioning coordinate transformation system suitable for unmanned driving formations. The positioning coordinate transformation is performed using the positioning coordinate transformation system suitable for unmanned driving formations.
[0033] In some embodiments, the aforementioned positioning coordinate transformation system suitable for unmanned formations can also be implemented in the following ways.
[0034] Example 1: Slanted Mercator Local Projection Master-Slave Node Collaborative Calibration Solution This embodiment combines the concept of "the relative positions of vehicles within an unmanned platoon" (… Based on the characteristics of "vehicle-to-vehicle communication capability", a solution of "oblique Mercator local projection + master-slave node collaborative calibration" is proposed. The system architecture is as follows: Figure 1 As shown: the entire link from vehicle-mounted terminal to vehicle-to-vehicle communication to collaborative control to projection conversion, with the specific solution as follows: 1.1 System Overall Architecture This system consists of three core units, which interact with each other via the vehicle bus (CAN / LIN) and the vehicle-to-vehicle communication network (5G-V2X): (1) Vehicle-mounted sensing and computing terminal: responsible for GNSS data acquisition, projection calculation and local status storage; (2) Vehicle-to-vehicle cooperative control unit: realizes the identity management of master and slave nodes in the formation, the synchronization of reference points and the control of calibration logic; (3) Oblique Mercator projection conversion unit: core algorithm module, realizing latitude and longitude. Precise conversion of ENU coordinates.
[0035] 1.2 Detailed Description of Each Component 1.2.1 Vehicle-mounted sensing and computing terminal (hardware core) Core functions: Acquiring Global Navigation Satellite System (GNSS) data, performing projection calculations, and storing reference parameters. Specific components are as follows: (1) GNSS module: The output data includes latitude and longitude (WGS-84 coordinate system), location confidence, and velocity information; (2) Vehicle-mounted edge processor: It has a high-performance computing processor that supports real-time oblique Mercator projection calculation and has the ability to store and update historical trajectories and map data (pre-existing high-precision maps); (3) 5G-V2X communication module: supports PC5 direct communication, used to send / receive reference point data, master-slave identity information and calibration status; (4) Human-computer interaction unit (navigation vehicle only): includes a display screen and an audio-visual alarm, used to show the navigation vehicle driver “calibration status”, “calibration request” and “calibration result”, and to issue an audio-visual reminder when static calibration is required.
[0036] 1.2.2 Oblique Mercator Projection Conversion Unit (Algorithm Core) Core function: To generate latitude and longitude coordinates using the oblique Mercator projection with a specified reference point as the center. The ENU coordinate transformation solves the problem of local distortion. The specific algorithm design is as follows: (1) Principle of oblique Mercator projection: Oblique Mercator projection is an "oblique variant" of standard Mercator projection. The cylindrical projection surface is tangent to the Earth's surface at an arbitrary angle (rather than the standard Mercator equator tangency or the central meridian tangency of the UTM). The tangent trajectory can be set along the formation's travel route (such as a diagonal line or curve) to ensure that the local area of the formation's travel (around the reference point) is tangent. It is always in the projection "low distortion zone".
[0037] (2) Projection parameter design: Reference point: Select the initial GNSS latitude and longitude of the formation master node (lead vehicle). As the origin of the projection, the transformed ENU coordinates of this point are: ; (3) Coordinate transformation formula (simplified form): Let the latitude and longitude of the target point be... Transformed ENU coordinates The calculation is performed using the following steps: ① Calculate the spherical distance between the target point and the reference point ( ) and azimuth ( ); ② Based on the conformal characteristics of the oblique Mercator projection, the spherical distance Convert to planar distance (S), azimuth ③ The decomposed planar distance S is the eastward component. Northward component Complete the ENU coordinate transformation.
[0038] 1.2.3 Vehicle-to-Vehicle Cooperative Control Unit (Cooperative Core) Core functions: Implement master-slave node management, reference point synchronization, and calibration process control within the formation to ensure that all vehicle coordinate systems are consistent. The specific logic is shown in Table 1. Table 1: Master-Slave Node Identity Design Logic Table
[0039] Use periodic messages (recommended period) To avoid the complexity of request / response logic in event-driven messages, the message format is based on Protobuf encoding, and the core fields included are shown in Table 2: Table 2: Vehicle-to-Vehicle Communication Message Design Table
[0040] The benchmark point collaborative calibration process is divided into two categories: "calibration upon joining the platoon" and "calibration during long-distance travel." The core steps are the same, as follows (taking calibration upon joining the platoon as an example): (1) Calibration trigger: The following vehicle (slave node) sends an enqueue request to the navigator vehicle (master node). After the master node agrees, it broadcasts a "calibration start" message (calibration_state=true) to all slave nodes. (2) Static verification: The master node obtains the vehicle speed (vehicle_speed) of all slave nodes through vehicle-to-vehicle communication to confirm the vehicle speed of all vehicles. And continue (Ensure all vehicles are stationary); if any vehicle is not stationary, the master node will alert the lead vehicle driver via an audible and visual alarm, and continue only after all vehicles have come to a complete stop; (3) Baseline point synchronization: The master node broadcasts its own base latitude and longitude (base_latitude, base_longitude); after receiving the base latitude and longitude from the slave node, it starts local update: recalculates all location information related to the unfolded point, including but not limited to historical trajectory and ENU value of the prior high-precision map, and replaces the coordinate data under the original baseline; (4) Status feedback: After the slave node completes the local update, it sets calibration_state to false and calibration_result to SUCCESS and sends feedback to the master node; (5) Calibration determination: The master node detects the feedback status of all slave nodes in real time. If all slave nodes are "calibration_state=false and calibration_result=SUCCESS", the calibration is determined to be successful. The master node sets its own calibration_state to false and broadcasts a "calibration complete" message. If a slave node reports FAIL (such as local update timeout), the master node triggers a rollback mechanism: all nodes restore the master node's reference latitude and longitude before calibration, broadcast a "calibration failed, rollback to the original reference" message, and retry after the vehicle stops again.
[0041] When the master node (navigation vehicle) detects the radial distance between its current position and the reference point... When (the spherical distance is calculated via GNSS), the following process is triggered: (1) The master node obtains the vehicle speed of all slave nodes through vehicle-to-vehicle communication and determines whether they are all equal. And continue (2) If the static condition is met, the master node displays a "calibration reminder" to the navigator driver through the human-machine interaction unit, including "estimated calibration time". The option “Whether to start calibration”; (3) After the driver confirms the start, the master node executes the “baseline point collaborative calibration process”; if the driver refuses, the master node will remind the driver again after the rule logic is met (such as after a certain interval, or after driving a certain distance again, or other rules), until the calibration is completed. The driver can also actively trigger the calibration at an appropriate time.
[0042] 1.3 System Workflow (Taking truck platooning as an example: Onboard terminal → Vehicle-to-vehicle communication → Cooperative control → Projection conversion full link) like Figure 2 As shown, the process of the positioning coordinate transformation method suitable for unmanned driving formations includes: Single-vehicle startup phase: The lead vehicle and follower vehicles start their systems separately. When acquiring valid GNSS data for the first time, each vehicle uses that latitude and longitude as a reference and converts it to ENU coordinates via oblique Mercator projection (its own coordinates being the master node). (Its initial latitude and longitude). Formation formation phase: Follower vehicles send joining requests to the lead vehicle. The lead vehicle agreed Master node (navigator) triggers calibration All vehicles are stationary. Synchronous reference latitude and longitude Calibration complete; coordinate systems of all vehicles within the formation now unified. Long-distance driving phase: The formation travels along the planned route, and all vehicles convert ENU coordinates in real time based on a unified reference oblique Mercator projection to achieve collaborative perception and control; Long-distance calibration phase: The lead vehicle detects the distance to the reference point. Confirm all vehicles are stationary Driver confirms calibration Perform calibration Update the reference point and continue driving; Formation disbandment phase: Follow-up vehicles send departure requests. Master node agrees The following vehicle switches to a single vehicle master node, using the current latitude and longitude as the new benchmark, and independently performs coordinate transformation.
[0043] Example 2: Standard Mercator projection scheme in low-latitude scenarios 2.1 Overview of the Solution This scheme is a simplified alternative to the oblique Mercator projection, suitable for latitudes < In low-latitude regions. Core logic: Utilizing the characteristic that the distortion rate of the standard Mercator projection in low-latitude regions is close to that of the oblique Mercator projection, the standard Mercator projection is used instead of the oblique Mercator projection, simplifying the algorithm complexity and reducing the computational load on the onboard processor.
[0044] 2.2 Adjustment of Scheme Composition (1) Projection algorithm adjustment: Delete the oblique Mercator projection unit and replace it with the standard Mercator projection algorithm (with the equator as the projection reference and the conformal characteristics unchanged). (2) The design of the reference point remains unchanged: the initial latitude and longitude of the master node are still used as the reference point, and the standard Mercator coordinates of the point are mapped to... Ensure that the formation coordinate system is consistent; (3) Distortion control range: In low latitude regions, the standard Mercator projection distortion rate is small within the range around the reference point, which meets the positioning accuracy requirements. If it is necessary to cooperate with this scheme, the radial distance mentioned in the calibration timing can be appropriately reduced to further control the error.
[0045] 2.3 Beneficial Effects: The algorithm complexity is reduced, which decreases the single-frame computation time of the on-board processor and reduces energy consumption; there is no need to design the tilt angle parameters of the oblique Mercator projection, simplifying the system configuration process; it is compatible with the original vehicle-to-vehicle cooperative calibration logic, requiring no changes to hardware and communication modules, resulting in low modification costs.
[0046] Example 3: Collaborative Calibration Optimization Scheme with Timeout Detection 3.1 Overview of the Solution This solution is a functional extension of the original "vehicle-to-vehicle cooperative control unit". The core logic is to add a "timeout detection mechanism" to the benchmark calibration process to avoid the entire formation waiting for calibration for a long time due to the failure of individual slave nodes, thereby improving the robustness of the system.
[0047] 3.2 Adjustment of Scheme Composition (1) Add a timeout detection module: Set the "calibration timeout threshold" on the master node (default). (Configurable), timing begins when calibration starts; (2) Timeout handling logic: If the timeout is... If all slave nodes have completed calibration, the original procedure is followed to determine success; if timing is not complete... If any slave node fails to report calibration results, all nodes will trigger a rollback mechanism. The master node will continue to use the previous baseline expansion point, and all slave nodes will also use the previous master node's baseline expansion point.
[0048] 3.3 Beneficial Effects To avoid excessive waiting time for formation calibration due to the failure of a single slave node (reduced from infinite waiting to within 10 seconds), thus improving the efficiency of long-distance transportation; the offline recovery mechanism for faulty nodes ensures that the formation does not need to be disbanded, and only the faulty node needs to be handled individually, thus ensuring the integrity of the formation.
[0049] Example 4: Event-based vehicle-to-vehicle communication optimization scheme 4.1 Overview of the Solution This solution is an optimization of the original "vehicle-to-vehicle communication message" transmission. The core logic is to change the "periodic message" to a combination of "event message + heartbeat message". Complete reference data is sent only when collaborative calibration is required (event triggered), and simplified heartbeat messages are sent during daily driving to reduce the waste of air interface communication resources.
[0050] 4.2 Adjustment of Scheme Composition (1) Message type splitting: Heartbeat message (cycle) ): Contains only the node_type, vehicle_speed, and calibration_state fields; data volume byte; Calibration event message (triggered): Sent only when calibration is initiated, contains complete fields (base_latitude, base_longitude, etc.), data size byte; (2) Triggering mechanism design: When the master node starts calibration, it actively broadcasts a calibration event message. Send three times consecutively to ensure reception from the node. After receiving a calibration event message from the node, a calibration event message is sent when the calibration status is reported (only once, after which a heartbeat message is resumed).
[0051] 4.3 Beneficial Effects Reduced communication data volume during daily driving (from Down to This reduces 5G-V2X channel occupancy and avoids communication conflicts with other vehicles; the multiple-sending mechanism for calibration events improves message reception success rate and ensures reliable triggering of the calibration process.
[0052] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.
Claims
1. A positioning coordinate transformation system suitable for unmanned driving formations, characterized in that, It includes an onboard sensing and computing terminal, a Mercator projection conversion unit, and a vehicle-to-vehicle cooperative control unit; the onboard sensing and computing terminal, the Mercator projection conversion unit, and the vehicle-to-vehicle cooperative control unit achieve data interaction through an onboard bus and a vehicle-to-vehicle communication network; the onboard sensing and computing terminal is used for global navigation satellite system data acquisition, projection calculation, and reference parameter storage; the Mercator projection conversion unit is used for coordinate transformation using the Mercator projection method with a specified reference point as the center; the vehicle-to-vehicle cooperative control unit is used for master-slave node identity management within the formation, reference point synchronization, and calibration process control to ensure that the coordinate system of all vehicles is consistent.
2. The positioning coordinate transformation system suitable for unmanned driving formations according to claim 1, characterized in that, The vehicle-mounted sensing and computing terminal includes a GNSS module, a vehicle-mounted edge processor, a vehicle-mounted communication module, and a human-machine interaction unit. The GNSS module is used to acquire latitude and longitude, location accuracy, and speed information. The vehicle-mounted edge processor is used for projection calculation, storage and updating of historical trajectory and map data. The vehicle-mounted communication module is used for direct communication, sending and / or receiving reference point data, master-slave identity information, and calibration status. The human-machine interaction unit is used to output calibration status, calibration request, calibration result, and audio-visual reminders.
3. The positioning coordinate transformation system suitable for unmanned driving formations according to claim 1, characterized in that, The coordinate transformation method is the oblique Mercator projection method.
4. The positioning coordinate transformation system suitable for unmanned driving formations according to claim 1, characterized in that, The coordinate transformation method is the standard Mercator projection method.
5. The positioning coordinate transformation system suitable for unmanned driving formations according to claim 1, characterized in that, The management of master and slave node identities within the formation includes: when a vehicle has not joined the formation, it is set as the master node; after a vehicle successfully joins the formation, if the vehicle is set as the lead vehicle, it becomes the master node; if the vehicle is not set as the lead vehicle, it becomes the slave node; the master node is used to store and broadcast the formation's reference latitude and longitude, initiate the calibration process, check the calibration status of all slave nodes, determine whether the calibration is successful, and trigger a rollback mechanism; the slave nodes are used to receive the reference latitude and longitude broadcast by the master node, recalculate historical trajectories, update reference points such as the east-north-sky coordinates of map data, and report the calibration progress and results back to the master node.
6. The positioning coordinate transformation system suitable for unmanned driving formations according to claim 1, characterized in that, The communication messages of the vehicle-to-vehicle cooperative control unit include event messages, which include a node type field, a reference point latitude field, a reference point longitude field, a reference point synchronization status field, a current vehicle speed field, and a calibration result field.
7. The positioning coordinate transformation system suitable for unmanned driving formations according to claim 6, characterized in that, The communication message also includes a heartbeat message, which includes a node type field, a current vehicle speed field, and a calibration result field.
8. The positioning coordinate transformation system suitable for unmanned driving formations according to claim 1, characterized in that, The process of controlling the reference point synchronization and calibration procedure includes: ① Calibration Trigger: The slave node sends an enqueue request to the master node. After the master node agrees, it broadcasts a calibration start message to all slave nodes. ② Static Verification: Based on the vehicle speeds of all slave nodes, confirm that all vehicles are stationary and for what duration. If a vehicle is not stationary, the master node will issue an audible and visual alarm. ③ Reference point synchronization: The master node broadcasts the master node's reference latitude and longitude; the slave node receives the master node's reference latitude and longitude and initiates a local update on the slave node: recalculate all location information related to the unfolded point, including historical trajectories and the East-North-Sky coordinate values of the prior high-precision map, and replace the coordinate data under the original reference. ④ Status Feedback: After the slave node completes the local update, it sets the reference point synchronization status of the slave node to false and the calibration result to pass, and feeds back the reference point synchronization status and calibration result to the master node. ⑤ Calibration Judgment: If the reference point synchronization status of all slave nodes is false and the calibration result is passed, the calibration is considered successful, the reference point synchronization status of the master node is set to false, and a "calibration complete" message is broadcast; if the calibration result of at least one slave node is failed, the master node rollback mechanism is triggered: all master nodes and slave nodes resume using the master node reference latitude and longitude before calibration, broadcast a calibration failure rollback to the original reference message, and retry after the vehicle stops again; ⑥ Confirm the radial distance between the current position of the master node and the reference point. And all vehicles are stationary for a period of time. The main node's human-computer interaction unit generates a calibration reminder, confirms the start of calibration, and returns to step ①.
9. The positioning coordinate transformation system suitable for unmanned driving formations according to claim 8, characterized in that, The process of synchronizing and calibrating the reference point also includes: starting the timer when calibration is initiated; if all slave nodes complete calibration within the calibration timeout threshold, the calibration is considered successful; otherwise, all nodes trigger the rollback mechanism, the master node uses the previous reference expansion point, and all slave nodes also use the previous master node's reference expansion point.
10. A method for positioning coordinate transformation suitable for unmanned formations, applied to the positioning coordinate transformation system suitable for unmanned formations as described in any one of claims 1-9, characterized in that, The positioning coordinates are transformed using the positioning coordinate transformation system suitable for unmanned driving formations.