A river environment simultaneous localization and mapping method and system based on multi-sensor fusion

Abstract

This invention relates to the field of water surface mapping and navigation positioning technology, and discloses a method and system for synchronous positioning and map construction in river environments based on multi-sensor fusion. The method includes: collecting multi-source sensor data of the river, generating fused data through time synchronization and spatial registration; extracting shoreline contour point sequences and inertial data; identifying shoreline direction and spacing changes to generate geometric constraints, and correcting the motion direction to obtain a corrected pose by combining inertial data; obtaining water depth distribution from sonar bathymetry data, generating a riverbed topographic map and associating it with the corrected pose; constructing shoreline layer and water depth layer maps, spatially associating and fusing them to generate a multi-layer fused map; and updating the carrier position in real time based on the fused map. This invention aims to solve the problems of difficulty in unified fusion of multi-source sensor data, easy drift of carrier inertial heading, lack of effective association between shoreline information and underwater topographic information, isolated map layers, and insufficient robustness of real-time positioning in complex river environments.

Description

Technical Field

[0001] This invention relates to the field of water surface surveying and navigation positioning technology, and in particular to a method and system for synchronous positioning and map construction of river environment based on multi-sensor fusion. Background Technology

[0002] Synchronous localization and mapping (SMR) of the river environment is a crucial foundation for waterway surveying, waterway monitoring, and unmanned surface vessel (USV) navigation. Existing technologies typically utilize devices such as GNSS, inertial measurement units (INS), visual sensors, lidar, and sonar mounted on the water surface or underwater to acquire position, attitude, visual, and acoustic information within the river environment. River environments are generally characterized by features such as curved shorelines, varying widths, bridge and vegetation obstructions, water surface reflection, and significant multipath effects. In such environments, various sensors acquire data at different sampling frequencies and operating modes, which are then used for navigation and environmental perception.

[0003] However, under complex conditions such as curved riverbanks, bridge vegetation obstruction, and significant water surface reflection, GNSS signals become discontinuous due to obstruction and reflection. Inertial measurement units accumulate heading errors over time due to integration calculations. Visual and lidar systems mis-extract features due to water surface fluctuations and obstruction. Sonar depth sounding produces beam pointing errors due to carrier attitude changes and transducer deviations. Because of differences in time references, spatial references, and installation locations among multiple sensors, spatiotemporal misalignment occurs during data fusion. Shoreline information and underwater topographic information are difficult to accurately correlate, resulting in isolated map layers and contradictions during fusion. These errors accumulate and propagate over time in complex river environments, causing lateral offsets and heading deviations in real-time positioning. In degraded scenarios such as GNSS rejection or flat water depth, positioning robustness is insufficient. Summary of the Invention

[0004] This invention provides a method and system for synchronous positioning and mapping in river environments based on multi-sensor fusion. Its main purpose is to solve the problems of difficulty in unifying and fusing multi-source sensor data, easy drift of carrier inertial heading, lack of effective correlation between shoreline information and underwater topographic information, isolated map hierarchy, and insufficient robustness of real-time positioning in complex river environments.

[0005] To achieve the above objectives, this invention provides a method for simultaneous localization and mapping of river environments based on multi-sensor fusion, comprising: S1: Using a carrier equipped with multi-source sensors, collect multi-source sensor data in the river environment, and perform time synchronization and spatial registration on the multi-source sensor data to generate sensor fusion data; S2: Extract riverbank contour features from the sensor fusion data, generate a shoreline contour point sequence, and extract inertial measurement data from the sensor fusion data; S3: Based on the shoreline contour point sequence, identify the shoreline direction and shoreline spacing change trend on both sides of the river, generate shoreline geometric constraint relationship, determine the motion direction of the carrier according to the inertial measurement data, and when the motion direction deviates from the shoreline direction, correct the motion direction according to the shoreline geometric constraint relationship to generate carrier correction pose information; S4: Using the sonar depth data in the sensor fusion data, obtain the water depth values ​​at various locations on the bottom of the river. Determine the topographic undulation features of the bottom of the river based on the spatial distribution of the water depth values. Associate the topographic undulation features with the carrier's corrected pose information to generate a topographic map of the bottom of the river. S5: Construct the shoreline contour point sequence into a shoreline layer map, construct the riverbed topographic map into a water depth layer map, determine the spatial correspondence between the shoreline layer map and the water depth map based on the carrier correction pose information, perform spatial association fusion, and generate a multi-layer fused map of the river environment. S6: Based on the multi-layer fusion map of the river environment, the position of the carrier is updated in real time to generate real-time location information.

[0006] Preferably, the step of performing time synchronization and spatial registration of the multi-source sensor data to generate sensor fusion data includes: The cross section of the river channel is calibrated using the acquisition time and heading data from the multi-source sensor data, and the multi-source sensor data is merged into the cross section of the river channel to obtain time synchronization data. Based on the time synchronization data, the sonar depth data in the multi-source sensor data is corrected to the water surface elevation in the multi-source sensor data to obtain the vertical position assignment; Under the given vertical position assignment, the two ends of the water surface span and the depth measurement span in the multi-source sensor data are relatively coincided to obtain the lateral reference; Based on the vertical position attribution and the lateral reference, spatial registration is performed on the observation data from each source sensor in the multi-source sensor data to obtain the sensor fusion data.

[0007] Preferably, the step of identifying the shoreline orientation and shoreline spacing variation trend on both sides of the river based on the shoreline contour point sequence, and generating shoreline geometric constraint relationships, includes: Based on adjacent shoreline contour points in the shoreline contour point sequence, the shoreline orientation on both sides of the river channel is identified. By combining the orientation of the shorelines on both sides of the river channel and comparing the distance between paired shoreline contour points in the shoreline contour point sequence, the trend of the change in the shoreline spacing on both sides of the river channel can be identified. The trend of the distance between the banks of the river is used to verify the orientation of the banks of the river, and the corrected orientation of the banks is obtained. Remove shoreline contour points from the shoreline contour point sequence that do not match the corrected shoreline direction to obtain matching shoreline contour points; The riverbanks are constrained by the matching shoreline contour points and the trend of shoreline spacing changes, thus generating a shoreline geometric constraint relationship.

[0008] Preferably, the step of determining the motion direction of the carrier based on the inertial measurement data, and correcting the motion direction according to the geometric constraints of the shoreline when the motion direction deviates from the shoreline direction to generate carrier corrected pose information, includes: The direction of motion of the carrier is determined based on the relationship between the heading angle in the inertial measurement data and the geometric constraints of the shoreline; By comparing the direction of motion with the direction of the shoreline, the heading deviation of the direction of motion relative to the direction of the shoreline is obtained; Check the turning point of the course deviation and the shoreline direction along the trend of the shoreline spacing change, and mark the river channel turning deviation that follows the shoreline turning. After excluding the river channel turning deviation, the heading deviation that deviates from the shoreline direction is identified based on the shoreline geometric constraints. Based on the heading drift deviation and the river course turning deviation, the motion direction is corrected to generate carrier corrected pose information.

[0009] Preferably, the step of using sonar bathymetry data from the sensor fusion data to obtain water depth values ​​at various locations on the riverbed includes: Using the sonar depth data in the sensor fusion data, the beam slant range value of each beam is extracted; Based on the beam emission angle in the sonar depth sounding data and the roll and pitch angles in the carrier's corrected pose information, the actual direction of each beam is restored. Starting from the position of the sonar transducer determined by the carrier's corrected pose information, the beam slant range value is extended along the actual direction to obtain the echo point at the bottom of the river channel. Based on the shoreline orientation in the shoreline geometric constraint relationship, shoreline points located at the junction of the riverbank and the water surface are selected from the shoreline contour point sequence to obtain the waterfront points; Using the vertical height of the waterline point as the starting point, the water depth values ​​at each location on the bottom of the river channel at the echo point are obtained.

[0010] Preferably, the step of determining the topographic relief features of the riverbed based on the spatial distribution of the water depth values, and associating the topographic relief features with the carrier's corrected pose information to generate a riverbed topographic map includes: By comparing adjacent spatial distributions of the water depth values ​​based on the known spacing of the beam footprints in the sonar bathymetry data, the topographic abrupt boundary at the bottom of the river channel is obtained. The riverbed is categorized by the angle between the abrupt change boundary and the direction of the shoreline, thus obtaining the topographic undulation characteristics of the riverbed. Using the deep trench orientation of the terrain undulation features as a reference, the deviation of the carrier's corrected pose information is compared to obtain the pose deviation of the carrier's corrected pose information. The carrier's corrected pose information is reverse-corrected according to the pose deviation to obtain a matching pose associated with the terrain undulation features and the carrier's corrected pose information. The spatial distribution of the water depth values ​​is sequentially spread out using the matching pose to obtain a topographic map of the riverbed where the map boundary of the riverbed coincides with the sequence of shoreline contour points.

[0011] Preferably, the step of constructing a shoreline layer map from the sequence of shoreline contour points and constructing a depth layer map from the riverbed topographic map includes: According to the orientation of the carrier indicated by the carrier correction pose information, the shoreline contour point sequence is divided into columns to obtain the left shoreline elements and right shoreline elements of the shoreline contour point sequence. Along the direction of travel indicated by the carrier's corrected pose information, the left bank shoreline elements and the right bank shoreline elements are assigned numbers one by one, and the left bank shoreline elements and the right bank shoreline elements are combined in sequence to obtain a shoreline layer map. Starting from the left bank shoreline elements and the right bank shoreline elements, the water depth value at the bank of the river bottom topographic map is reset to zero to obtain the bank slope section. By performing deep channel demarcation on the riverbed topographic map along the bank slope and the water depth value, a water depth map is obtained.

[0012] Preferably, the step of determining the spatial correspondence between the shoreline layer map and the water depth layer map based on the carrier-corrected pose information, and performing spatial correlation fusion to generate a multi-layer fused map of the river environment includes: Based on the carrier's corrected pose information, the shoreline layer map and the water depth layer map are paired position by position to determine their spatial correspondence. Based on the spatial correspondence and the water depth value, the water boundary is identified in the water depth map; By cross-referencing the waterfront boundary with the shoreline contour point sequence, the shoreline water depth correlation zone in the spatial correspondence is obtained; Based on the shoreline water depth correlation zone, the shoreline layer map and the water depth layer map are spatially correlated and fused to obtain the spatial correlation fusion result; Based on the spatial correlation fusion result and the geometric constraint relationship of the shoreline, the shoreline contour point sequence is selected and discarded to generate a multi-level fused map of the river environment.

[0013] Preferably, the multi-layered fusion map based on the river environment performs real-time location updates on the carrier's position to generate real-time location information, including: The shoreline contour point sequence is projected onto the shoreline layer map and compared with the left and right shoreline point sequences along the shoreline direction to obtain the lateral offset in the position of the carrier. Based on the lateral offset and the trend of the shoreline spacing change, the shoreline spacing is compared segment by segment to obtain the equal-width segments in the shoreline layer map; By comparing the water depth distribution of the riverbed topographic map and the water depth map within the equal width section, the shoreline offset in the water depth map is obtained. The coastal offset is verified using the motion direction and the shoreline geometric constraint relationship to obtain the position update result of the carrier. Based on the multi-layered fused map and the location update results, the location of the carrier is updated in real time to generate real-time location information.

[0014] To address the aforementioned problems, this invention also provides a river environment synchronous localization and mapping system based on multi-sensor fusion, comprising: Synchronization and registration module: Utilizing a carrier equipped with multi-source sensors, it collects multi-source sensor data in the river environment, performs time synchronization and spatial registration on the multi-source sensor data, and generates sensor fusion data; Feature extraction module: Extracts riverbank contour features from the sensor fusion data, generates a sequence of shoreline contour points, and extracts inertial measurement data from the sensor fusion data; Pose correction module: Based on the shoreline contour point sequence, identify the shoreline direction and shoreline spacing change trend on both sides of the river, generate shoreline geometric constraint relationship, determine the motion direction of the carrier according to the inertial measurement data, and when the motion direction deviates from the shoreline direction, correct the motion direction according to the shoreline geometric constraint relationship to generate carrier corrected pose information; Terrain construction module: Using sonar depth data from the sensor fusion data, the water depth values ​​at various locations on the bottom of the river are obtained. Based on the spatial distribution of the water depth values, the topographic undulation features of the bottom of the river are determined. The topographic undulation features are correlated with the carrier's corrected pose information to generate a topographic map of the bottom of the river. Map fusion module: Constructs the shoreline contour point sequence into a shoreline layer map, constructs the riverbed topographic map into a water depth layer map, determines the spatial correspondence between the shoreline layer map and the water depth map based on the carrier correction pose information, performs spatial association fusion, and generates a multi-layer fused map of the river environment. Location update module: Based on the multi-layer fusion map of the river environment, the location of the carrier is updated in real time to generate real-time location information.

[0015] Beneficial effects This solution collects multi-source sensor data from the river channel and performs time synchronization and spatial registration. It extracts shoreline contour point sequences and inertial measurement data from the fused data, identifies the shoreline orientation and spacing variation trends on both sides of the river, and generates shoreline geometric constraints. Then, it combines inertial measurement data to correct the carrier's motion direction. This approach unifies data from different sensors under the same time and space reference and uses shoreline orientation and river width variations as references for course correction. It achieves relatively accurate carrier pose even under complex conditions such as shoreline curvature, bridge vegetation obstruction, and water surface reflection. This solution solves the problems of difficulty in unifying and fusing multi-source sensor data, easy drift of carrier inertial heading, and lack of effective correlation between shoreline information and underwater topographic information in existing technologies. It has the advantages of improving the accuracy of multi-source data fusion, suppressing the accumulation of heading errors, and enhancing adaptability to complex river environments.

[0016] This solution acquires water depth at various locations on the riverbed using sonar bathymetry data and generates a riverbed topographic map. It constructs a shoreline layer map from the sequence of shoreline contour points and a water depth layer map from the riverbed topographic map. Then, based on the corrected pose, it determines the spatial correspondence between the two and fuses them to generate a multi-layered fused map. This map is used for real-time positioning updates of the carrier's location. This achieves mutual correspondence between the shoreline layer and the water depth layer under the same spatial reference, and the map layers are no longer isolated. It realizes mutual verification and continuous correction between shoreline boundaries, water depth distribution, and carrier location, solving the problems of isolated map layers, contradictions during fusion, and insufficient real-time positioning robustness in existing technologies. It offers advantages such as more complete map representation, more stable positioning results, and good positioning performance even in scenarios with GNSS rejection or flat and degraded underwater topography. Simultaneously, it uses the corrected pose to restore the actual sonar beam direction, reducing the impact of carrier attitude changes and transducer installation deviations on water depth measurement. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating a method for synchronous localization and map construction of river environment based on multi-sensor fusion, provided in an embodiment of the present invention.

[0018] Figure 2A functional module diagram of a river environment synchronous positioning and mapping system based on multi-sensor fusion provided in an embodiment of the present invention;

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0021] This application provides a method and system for synchronous localization and mapping of river environments based on multi-sensor fusion. The executing entity of this method and system includes, but is not limited to, at least one of the following electronic devices that can be configured to execute the method provided in this application: a server, a terminal, etc. In other words, the method and system for synchronous localization and mapping of river environments based on multi-sensor fusion can be executed by software or hardware installed on a terminal device or a server device. The server includes, but is not limited to, a single server, a server cluster, a cloud server, or a cluster of cloud servers. The server can be an independent server or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, content delivery networks (CDNs), and big data and artificial intelligence platforms.

[0022] Reference Figure 1 The diagram shown is a flowchart illustrating a method and system for simultaneous localization and mapping of river environments based on multi-sensor fusion, according to an embodiment of the present invention. In this embodiment, the method for simultaneous localization and mapping of river environments based on multi-sensor fusion includes:

[0023] S1: Using a carrier equipped with multi-source sensors, collect multi-source sensor data in the river environment, and perform time synchronization and spatial registration on the multi-source sensor data to generate sensor fusion data;

[0024] In this embodiment, the step of performing time synchronization and spatial registration of the multi-source sensor data to generate sensor fusion data includes: The cross section of the river channel is calibrated using the acquisition time and heading data from the multi-source sensor data, and the multi-source sensor data is merged into the cross section of the river channel to obtain time synchronization data. Based on the time synchronization data, the sonar depth data in the multi-source sensor data is corrected to the water surface elevation in the multi-source sensor data to obtain the vertical position assignment; Under the given vertical position assignment, the two ends of the water surface span and the depth measurement span in the multi-source sensor data are relatively coincided to obtain the lateral reference; Based on the vertical position attribution and the lateral reference, spatial registration is performed on the observation data from each source sensor in the multi-source sensor data to obtain the sensor fusion data.

[0025] Specifically, multi-source sensors are a variety of sensing devices mounted on a carrier and used to collect observation data of different physical quantities in the river environment. They can acquire information such as shoreline, water depth, heading, attitude, and water surface height.

[0026] The carrier is a surface or underwater navigation platform that can move in the river environment and carry multiple source sensors, so that the multiple source sensors can acquire river environment data as they move.

[0027] The river environment is the aquatic space through which a vehicle travels, characterized by its shoreline, water surface, riverbed topography, and potential obstructions and reflections.

[0028] Multi-source sensor data is a collection of observation data acquired by multi-source sensors mounted on a carrier in the river environment. It includes at least the acquisition time, heading data, sonar bathymetry data, water surface elevation, water surface span, bathymetry span, and various observation data.

[0029] The acquisition time is the time information recorded when the multi-source sensor acquires the corresponding observation data, which is used to determine the position of the observation data in the time series.

[0030] Heading data is data that characterizes the direction of travel of a vehicle in a river environment and is used to determine the orientation of the vehicle relative to the direction of river extension.

[0031] A cross-section of a river channel is a cross section selected at intervals along the direction of the river's extension, perpendicular to the direction of the river's extension. It is used to organize and merge multi-source sensor data according to the cross-section.

[0032] Time synchronization data is obtained by merging multi-source sensor data into the transverse cross section of the river according to the acquisition time and heading data, so that the data collected by different sensors at different times correspond under the same cross section time reference.

[0033] Sonar depth sounding data is depth observation data obtained by sonar equipment in a multi-source sensor emitting sound waves to the riverbed and receiving the echoes. It is used to obtain water depth information at various locations on the bottom of the river.

[0034] Water surface elevation is the height information of the water surface relative to the same elevation benchmark in multi-source sensor data, used to provide the vertical starting position for sonar bathymetry data.

[0035] Vertical position attribution is the vertical correspondence obtained by correcting sonar bathymetry data to the water surface elevation in the vertical direction, so that the sonar bathymetry data and the water surface elevation are on the same vertical reference.

[0036] Water surface span is data from multi-source sensor data that characterizes the distance or coverage area of ​​the water surface in the lateral direction between the two banks, and is used to determine the lateral boundary of the water surface.

[0037] The sounding span is the lateral range covered by sonar sounding data or the lateral distance covered by the sounding beam, used to determine the lateral boundary of sonar sounding.

[0038] The lateral reference is a lateral alignment reference obtained by aligning the two ends of the water surface span and the depth sounding span under the vertical position assignment. It is used to unify the coordinate positions of different observation data in the lateral direction.

[0039] The observation data from each source is observation data from different sensors in the multi-source sensor data, including shoreline contour data, inertial measurement data, sonar bathymetry data, water surface elevation data, water surface span data, and bathymetry span data.

[0040] Spatial registration is the process of unifying observation data from various sources under the same spatial coordinate reference, so that data acquired by different sensors correspond to each other in terms of vertical position and lateral reference.

[0041] Sensor fusion data is the fused data obtained by time synchronization and spatial registration of various observation data. It is used for subsequent shoreline contour feature extraction, inertial measurement data extraction, sonar bathymetry data use, and map construction.

[0042] Furthermore, by using a carrier equipped with multi-source sensors to navigate in a river environment, the carrier collects multi-source sensor data from the river environment. This multi-source sensor data includes at least the acquisition time, heading data, sonar bathymetry data, water surface elevation, water surface span, bathymetry span, and observation data from each path.

[0043] Subsequently, the cross-section of the river channel was calibrated using the acquisition time and heading data from the multi-source sensor data. That is, the position of the data in the time series was determined based on the acquisition time, and the orientation of the carrier in the river channel was determined based on the heading data, thereby determining the position of the cross-section perpendicular to the river channel extension direction.

[0044] The multi-source sensor data are then merged into the corresponding cross-sections of the river channel according to their acquisition time and heading data, so that the data belonging to the same cross-section of the river channel are grouped together to obtain time-synchronized data.

[0045] Next, based on the time synchronization data, the sonar depth sounding data in the multi-source sensor data is corrected to the water surface elevation in the multi-source sensor data. That is, the sonar depth sounding data is aligned vertically to the same vertical reference represented by the water surface elevation to obtain the vertical position assignment.

[0046] Under the vertical position assignment, the two ends of the water surface span and the depth sounding span in the multi-source sensor data are relatively coincident, that is, the two boundary endpoints of the water surface span in the lateral direction correspond to the two boundary endpoints of the depth sounding span in the lateral direction, so as to obtain the lateral reference.

[0047] Finally, under the vertical position assignment and lateral reference, spatial registration is performed on the observation data of each source sensor data. That is, the observation data from different sensors are unified to the same spatial coordinate position, so that the observation data correspond to each other in both vertical and lateral directions, and sensor fusion data is obtained.

[0048] S2: Extract riverbank contour features from the sensor fusion data, generate a shoreline contour point sequence, and extract inertial measurement data from the sensor fusion data; Specifically, riverbank contour features are information from sensor fusion data reflecting the contour morphology of the water-land interface on both sides of the river. This information reflects the curvature and width variations of the shoreline, as well as the shoreline edges obscured by bridges and vegetation. This feature is the basis for generating a sequence of shoreline contour points.

[0049] A shoreline contour point sequence is a set of shoreline contour points arranged in the direction of river extension, derived from the features of the riverbank contour. Each shoreline contour point represents the location where the riverbank meets the water surface. The sequence includes shoreline points on the left bank and right bank. This sequence is used to identify the direction of the shorelines on both sides of the river and the trend of changes in the shoreline spacing.

[0050] Inertial measurement data (IGM) is the carrier's attitude and orientation data acquired by the inertial measurement unit (IMU) and separated from sensor fusion data. This data includes heading angle, roll angle, pitch angle, angular velocity, and acceleration. It is used to determine the carrier's direction of motion in the river channel. This data is also used for correction when the direction of motion deviates from the shoreline.

[0051] Furthermore, the observation data from various channels are retrieved first from the time-synchronized and spatially registered sensor fusion data. These observation data include shoreline contour data, inertial measurement data, sonar bathymetry data, water surface elevation data, water surface span data, and bathymetry span data. From these data, observation information related to the water-land interface location on both sides of the river is separated.

[0052] Then, the separated observation information is organized according to the transverse cross section of the river channel. The water surface elevation data is used to determine the vertical reference position of the water surface, and the water surface span data is used to determine the left and right boundaries of the water surface in the transverse direction. Combined with the candidate points of the land-water edge obtained by visual sensors and lidar, as well as the echo intensity changes formed by sonar bathymetry data in the near-shore area, the shoreline contour features at the junction of the riverbank and the water surface are identified.

[0053] Next, the discrete points, jump points, duplicate points and missing points in the shoreline contour features caused by water surface fluctuations, bridge obstruction, vegetation obstruction, water surface reflection and multipath effect are screened and corrected, and continuous shoreline contour points that conform to the shoreline direction are retained.

[0054] Subsequently, based on the heading data in the sensor fusion data or the heading angle in the inertial measurement data indicating the carrier's orientation and direction of travel, the retained shoreline contour points are divided into left bank shoreline points and right bank shoreline points. The left bank shoreline points and right bank shoreline points are then sorted and numbered along the river channel extension direction, so that each shoreline contour point has an order relationship along the river channel extension direction and an affiliation relationship with its corresponding bank, thus forming a shoreline contour point sequence.

[0055] At the same time, inertial measurement data is separated from the fused data of the same sensor. This inertial measurement data is provided by the inertial measurement unit and includes heading angle, roll angle, pitch angle, angular velocity, and acceleration. The heading angle, roll angle, pitch angle, angular velocity, and acceleration are arranged according to the acquisition time to obtain inertial measurement data related to the carrier's motion attitude and direction.

[0056] Finally, the shoreline contour point sequence and inertial measurement data are output separately. The shoreline contour point sequence is used to identify the shoreline orientation and shoreline spacing trend on both sides of the river and generate shoreline geometric constraints. The inertial measurement data is used to determine the motion direction of the carrier. When the motion direction deviates from the shoreline orientation, the motion direction is corrected according to the shoreline geometric constraints to generate the carrier's corrected pose information.

[0057] S3: Based on the shoreline contour point sequence, identify the shoreline direction and shoreline spacing change trend on both sides of the river, generate shoreline geometric constraint relationship, determine the motion direction of the carrier according to the inertial measurement data, and when the motion direction deviates from the shoreline direction, correct the motion direction according to the shoreline geometric constraint relationship to generate carrier correction pose information; In this embodiment, the step of identifying the shoreline orientation and shoreline spacing variation trend on both sides of the river based on the shoreline contour point sequence, and generating shoreline geometric constraint relationships, includes: Based on adjacent shoreline contour points in the shoreline contour point sequence, the shoreline orientation on both sides of the river channel is identified. By combining the orientation of the shorelines on both sides of the river channel and comparing the distance between paired shoreline contour points in the shoreline contour point sequence, the trend of the change in the shoreline spacing on both sides of the river channel can be identified. The trend of the distance between the banks of the river is used to verify the orientation of the banks of the river, and the corrected orientation of the banks is obtained. Remove shoreline contour points from the shoreline contour point sequence that do not match the corrected shoreline direction to obtain matching shoreline contour points; The riverbanks are constrained by the matching shoreline contour points and the trend of shoreline spacing changes, thus generating a shoreline geometric constraint relationship.

[0058] Specifically, adjacent shoreline contour points are two adjacent shoreline contour points ordered along the river channel extension direction in the same shoreline contour point sequence. The direction of the line connecting them reflects the local extension direction of the shoreline at that point, which is the basis for identifying the shoreline direction.

[0059] The two banks of the river are the two boundaries formed by the intersection of the river surface and the left and right banks. The left and right banks each have their own sequence of shoreline contour points, which are used to determine the changes in river width and constrain the direction of carrier movement.

[0060] The shoreline orientation is the direction of shoreline extension on both sides of the river channel identified by adjacent shoreline contour points in the shoreline contour point sequence. The left bank shoreline orientation and the right bank shoreline orientation represent the local orientation of the left and right banks in the direction of river channel extension, respectively.

[0061] Paired shoreline contour points are shoreline contour points located on the left and right banks respectively in the shoreline contour point sequence and corresponding to the same transverse section of the river channel or the same river-side sequence number. They are used to measure the distance between the two banks of the river at that point.

[0062] The spacing length is the lateral distance between paired shoreline contour points, representing the width of the water surface or the distance between the two banks of the river at that location along the river, used to identify changes in the width of the river channel, such as widening, narrowing, or approximate equal width.

[0063] The trend of shoreline spacing is obtained by comparing the distance between paired shoreline contour points along the river's extension direction. This includes whether the distance gradually increases, decreases, or remains stable. It is used to verify the shoreline direction and constrain the riverbanks.

[0064] Corrected shoreline orientation is a corrected orientation obtained by verifying the changing trend of the distance between the shorelines on both sides of the river. It is used to eliminate incorrect shoreline orientations caused by water surface fluctuations, bridge obstruction, vegetation obstruction, water surface reflection, and multipath effects.

[0065] Consistent shoreline contour points are the shoreline contour points retained after removing those that do not conform to the corrected shoreline orientation from the shoreline contour point sequence. They are consistent with and continuous with the corrected shoreline orientation and are used to generate shoreline geometric constraint relationships. Inconsistency means that the deviation of the shoreline contour point from the corrected shoreline orientation exceeds the range allowed for continuous shoreline extension.

[0066] The shoreline geometric constraint relationship is a geometric relationship generated by constraining the two banks of the river according to the shoreline contour points and the trend of shoreline spacing. It represents the boundary position, extension direction and width variation at different riverside positions on both banks of the river. It is used for subsequent correction of the direction of carrier movement and spatial correlation and fusion of shoreline layer map and water depth layer map.

[0067] Furthermore, based on adjacent shoreline contour points in the shoreline contour point sequence, adjacent points on the same bank are taken in pairs along the river channel extension direction to determine the direction of the line connecting each pair of adjacent points. This line direction is then used as the local extension direction of the shoreline at that location. The above processing is performed along the left bank and the right bank respectively to obtain the shoreline direction of the left bank and the shoreline direction of the right bank.

[0068] Combining the orientation of the left and right bank shorelines, select paired shoreline contour points located on the left and right banks respectively, corresponding to the same transverse section of the river channel or the same riverside sequence, and measure the distance between each pair of paired shoreline contour points.

[0069] By comparing the distance between each pair of shoreline contour points along the river's extension direction, we can determine that the river is widening at a certain point when the distance gradually increases, that the river is narrowing at a certain point when the distance gradually decreases, and that the river is approximately equal in width at a certain point when the distance remains stable. This gives us the trend of the distance between the shorelines on both sides of the river.

[0070] The trend of the shoreline spacing is used to check the orientation of the left and right shorelines. When the orientation of the left and right shorelines does not match the change in the spacing, the shoreline orientation is corrected to obtain a corrected shoreline orientation. The shoreline contour points are checked one by one along the shoreline contour point sequence. Discrete points, jump points, duplicate points, or erroneous points caused by water surface fluctuations, bridge obstruction, vegetation obstruction, water surface reflection, and multipath effects that deviate from the corrected shoreline orientation are removed. The shoreline contour points that are consistent with the corrected shoreline orientation are retained to obtain the matching shoreline contour points.

[0071] The boundary positions and extension directions of the riverbanks are determined by matching shoreline contour points, the width changes of the riverbanks at different riverside locations are determined by the trend of shoreline spacing changes, and the geometric positions and extension directions of the riverbanks are restricted by matching shoreline contour points and the trend of shoreline spacing changes, thus generating shoreline geometric constraint relationships.

[0072] In this embodiment, determining the motion direction of the carrier based on the inertial measurement data, and correcting the motion direction based on the shoreline geometric constraints when the motion direction deviates from the shoreline direction to generate carrier corrected pose information, includes: The direction of motion of the carrier is determined based on the relationship between the heading angle in the inertial measurement data and the geometric constraints of the shoreline; By comparing the direction of motion with the direction of the shoreline, the heading deviation of the direction of motion relative to the direction of the shoreline is obtained; Check the turning point of the course deviation and the shoreline direction along the trend of the shoreline spacing change, and mark the river channel turning deviation that follows the shoreline turning. After excluding the river channel turning deviation, the heading deviation that deviates from the shoreline direction is identified based on the shoreline geometric constraints. Based on the heading drift deviation and the river course turning deviation, the motion direction is corrected to generate carrier corrected pose information.

[0073] Specifically, the heading angle is the angle in inertial measurement data that characterizes the longitudinal axis of the carrier in the horizontal plane relative to a selected reference direction. It varies as the carrier travels along the river and is used to determine the carrier's current orientation and direction of motion.

[0074] The direction of motion of the carrier is determined by the heading angle in the inertial measurement data and the geometric constraints of the shoreline. It indicates whether the carrier is currently moving along the direction of the river or deviating relative to the direction of the river.

[0075] The heading deviation is the deviation of the vehicle's direction of motion relative to the shoreline direction obtained by comparing the vehicle's direction of motion with the shoreline direction. It represents the angle or degree of deviation of the vehicle's current heading relative to the direction of the riverbank extension.

[0076] The trend of shoreline spacing is obtained by comparing the distance between paired shoreline contour points along the river's extension direction. This includes whether the distance gradually increases, decreases, or remains stable. It is used to verify the shoreline direction and constrain the riverbanks.

[0077] A turning point in the direction of the shoreline is a location or section where the shoreline changes from one direction to another along the river channel. This can be manifested as a bend in the river channel, a turn in the shoreline, or a simultaneous change in the direction of the left and right shorelines. When a vehicle passes through this point, its course will change accordingly as the shoreline turns.

[0078] The deviation of the river course due to the turning of the shoreline is the reasonable deviation in the course deviation caused by the natural curvature of the river or the turning of the shoreline. It is represented by the change in course caused by the turning of the river course and does not belong to the drift caused by the cumulative error of inertial measurement.

[0079] The heading drift deviation is the deviation from the shoreline identified based on the geometric constraints of the shoreline after excluding the deviation from the river channel turning. It is caused by cumulative errors in inertial measurements, water surface reflection, bridge vegetation obstruction, multipath effects, or attitude changes, and belongs to unreasonable heading changes that need to be corrected.

[0080] The carrier's corrected pose information is generated after correcting the direction of motion based on the heading drift deviation and the river turning deviation. It includes the corrected heading angle and combines the pitch and roll angles from the inertial measurement data, which are used for subsequent sonar bathymetry data repositioning, terrain association, and map construction.

[0081] Furthermore, based on the relationship between the heading angle and the geometric constraints of the shoreline in the inertial measurement data, the direction of motion of the carrier is determined. The direction of motion is then compared with the direction of the shoreline to obtain the heading deviation of the direction of motion relative to the direction of the shoreline.

[0082] The trend of changes in shoreline spacing is compared with the turning point of the course deviation and the shoreline direction, and the river channel turning deviation that follows the shoreline turning is marked.

[0083] Calculate the rate of change of shoreline spacing in the current river segment, and calculate the rate of change of the vehicle's heading within the corresponding river segment based on inertial measurement data. Calculate the ratio of the rate of change of heading to the rate of change of shoreline spacing to obtain the steering coupling coefficient. The steering coupling coefficient is mainly obtained through the following steps: Step a: Obtain the shoreline change angle and corresponding river length of the current river segment, and divide the shoreline change angle by the corresponding river length to obtain the shoreline change rate; Step b: Obtain the heading change angle and corresponding river length of the carrier in the current river section, and divide the heading change angle by the corresponding river length to obtain the heading change rate; Step c: Divide the rate of change of heading by the rate of change of shoreline to obtain the steering coupling coefficient; Step d: Compare the steering coupling coefficient with the preset coupling threshold range. If it falls within the range, mark it as the river channel steering deviation as the shoreline turns.

[0084] The preset coupling threshold range can be determined statistically based on the ratio of the rate of change of navigation direction to the rate of change of shoreline direction in historical river sections, or calibrated based on the degree of river channel curvature.

[0085] The steering coupling coefficient is compared with a pre-set coupling threshold. When the steering coupling coefficient is within a reasonable range defined by the coupling threshold, the corresponding heading deviation is determined to be the river steering deviation due to the turning of the shoreline and is marked.

[0086] Subtract the river course deviation from the heading deviation to obtain the residual deviation. Project and decompose the residual deviation with the current river segment's shoreline orientation in the shoreline geometric constraints to obtain the longitudinal component along the river's extension direction and the lateral component perpendicular to the shoreline direction.

[0087] When the lateral component exceeds the lateral allowable range determined based on the trend of shoreline spacing changes, the lateral component is determined to be the heading drift deviation; when the longitudinal component exceeds the longitudinal allowable range determined based on the trend of shoreline spacing changes, the longitudinal component is determined to be the heading drift deviation.

[0088] The deviation from the river course is retained as a reasonable heading change component. A reverse correction proportional to the drift amplitude is applied to the heading deviation to obtain the heading correction value. The reasonable heading change component is then superimposed with the heading correction value to obtain the corrected heading angle.

[0089] Heading correction is mainly achieved through the following steps: Step a: Subtract the river course deviation from the heading deviation to obtain the residual deviation; Step b: Using the current riverbank orientation as the reference direction, decompose the residual deviation along the reference direction to obtain the longitudinal component; Step c: Decompose the residual deviation along the vertical reference direction to obtain the lateral component; Step d: Compare the lateral component with the preset lateral allowable range, and take the part that exceeds the preset lateral allowable range as the heading drift deviation; Step e: Multiply the heading drift deviation by a preset reverse correction ratio coefficient to obtain the reverse correction amount. The preset reverse correction ratio coefficient is a value that is greater than zero and less than one. Step f: Add the river course deviation to the reverse correction to obtain the heading correction value.

[0090] Among them, the preset lateral allowable range is determined based on the trend of shoreline spacing changes and the statistics of heading error.

[0091] Based on the position observations, dead reckoning results, and shoreline geometric constraints in the sensor fusion data, the corrected position of the carrier is determined, and the corrected position, corrected heading angle, pitch angle, and roll angle together constitute the corrected attitude information of the carrier.

[0092] The carrier's corrected pose information is used to suppress cumulative inertial heading drift in environments with curved riverbanks, bridge and vegetation obstruction, water surface reflection, and significant multipath effects. It also provides a unified pose reference for subsequent sonar bathymetry data repositioning, riverbed topographic map generation, and spatial correlation and fusion of shoreline layer maps and water depth layer maps.

[0093] S4: Using the sonar depth data in the sensor fusion data, obtain the water depth values ​​at various locations on the bottom of the river. Determine the topographic undulation features of the bottom of the river based on the spatial distribution of the water depth values. Associate the topographic undulation features with the carrier's corrected pose information to generate a topographic map of the bottom of the river. In this embodiment, obtaining water depth values ​​at various locations on the riverbed using sonar depth data from the sensor fusion data includes: Using the sonar depth data in the sensor fusion data, the beam slant range value of each beam is extracted; Based on the beam emission angle in the sonar depth sounding data and the roll and pitch angles in the carrier's corrected pose information, the actual direction of each beam is restored. Starting from the position of the sonar transducer determined by the carrier's corrected pose information, the beam slant range value is extended along the actual direction to obtain the echo point at the bottom of the river channel. Based on the shoreline orientation in the shoreline geometric constraint relationship, shoreline points located at the junction of the riverbank and the water surface are selected from the shoreline contour point sequence to obtain the waterfront points; Using the vertical height of the waterline point as the starting point, the water depth values ​​at each location on the bottom of the river channel at the echo point are obtained.

[0094] Specifically, a beam is a directional acoustic beam emitted and received by a sonar transducer towards the bottom of a river. Each beam forms an illumination area on the bottom of the river and generates an echo, which is the basic unit for obtaining the echo point on the bottom of the river.

[0095] The beam slant range is a measured distance along the beam propagation path between the sonar transducer and the echo point at the bottom of the river. It is determined by the round-trip time of the sound wave and the speed of sound in water, and represents the slant distance the beam travels from the sonar transducer to the bottom and back.

[0096] The beam emission angle is the directional angle of the beam centerline relative to the reference axis of the sonar equipment when the sonar transducer emits a beam. It is used to reconstruct the actual direction of the beam in the river environment by combining the carrier attitude.

[0097] The roll angle is an angular measure in the carrier's corrected pose information that represents the left and right tilt of the carrier around its longitudinal axis. It is generated when the river surface is fluctuating, turning, or the load is uneven, and it will affect the actual lateral direction of the sonar beam.

[0098] Pitch angle is an angular measure in the carrier's corrected pose information that represents the forward and backward tilt of the carrier around its horizontal axis. It is generated when the carrier accelerates, decelerates, experiences wave undulations, or passes through bridge areas, and it affects the actual longitudinal direction of the sonar beam.

[0099] The actual beam pointing is the true propagation direction of the beam in the river space, determined by the beam emission angle and the roll and pitch angles in the carrier's corrected attitude information. It is no longer limited to the ideal installation direction of the sonar equipment, but reflects the beam pointing after changes in the carrier's attitude. Specifically, step a: Obtain the beam emission angle from the sonar depth sounding data; Step b: Obtain the roll and pitch angles from the carrier's corrected pose information; Step c: The beam emission angle is laterally rotated and corrected according to the roll angle to obtain the lateral correction angle; Step d: Rotate the lateral correction angle longitudinally according to the pitch angle to obtain the longitudinal correction angle; Step e: Use the longitudinal correction angle as the actual pointing angle of the beam in the river channel space; Step f: Starting from the position of the sonar transducer, extend the beam slant range along the actual pointing angle to obtain the echo point at the bottom of the river.

[0100] The sonar transducer position is the coordinate position of the sonar transducer in the river space determined by the carrier's corrected pose information. It serves as the starting point of the beam propagation path and is used to convert the beam slant range value into the spatial position of the echo point at the bottom of the river.

[0101] The echo point is the location where the beam falls on the bottom of the river and generates a reflected echo after extending the beam slant distance along the actual direction. The set of echo points reflects the topographic undulations of the riverbed.

[0102] The shoreline geometric constraint relationship is a geometric relationship generated after identifying the direction of the shoreline and the trend of the shoreline spacing on both sides of the river based on the shoreline contour point sequence. It represents the boundary position, extension direction and width variation at different riverside locations on both sides of the river, and is used to constrain the direction of carrier movement and associate the shoreline layer with the water depth layer.

[0103] The shoreline orientation is the direction of shoreline extension on both sides of the river channel identified by adjacent shoreline contour points in the shoreline geometric constraint relationship. The left bank shoreline orientation and the right bank shoreline orientation represent the local orientation of the left and right banks in the direction of river channel extension, respectively, and are used to select shoreline points and correct pose.

[0104] The point where the riverbank meets the water is the location where the land or bank slope on both sides of the river meets the water. This point on the shoreline reflects both the direction of the shoreline and the elevation boundary of the water surface, and is the basis for determining the boundary line.

[0105] Shoreline points are points in the sequence of shoreline outline points that represent the location where the riverbank meets the water surface. They have an order relationship along the direction of river extension and belong to the bank. They are used to select the shoreline points located at the boundary between the riverbank and the water surface.

[0106] The shoreline point is a shoreline point selected from the shoreline outline point sequence based on the shoreline orientation in the shoreline geometric constraint relationship. It is located at the junction of the riverbank and the water surface. Its vertical height represents the elevation of the water surface or the shore-water junction at that point and is used as the starting surface for the water depth value.

[0107] Vertical height is the height of a point on the waterline relative to the same elevation datum in the vertical direction. It represents the elevation position at the boundary between the shore and the water, and is used to provide a starting point for determining the water depth at the bottom echo point of the river channel.

[0108] The datum plane is a reference plane determined by the vertical height of the point on the waterline. It is used to calculate the water depth value of each echo point at the bottom of the river from this plane, so that the water depth value has a unified vertical reference.

[0109] The water depth value is the vertical distance from the bottom of the riverbed at the echo point to the vertical height of the boundary line point. It represents the water depth from the water surface to the bottom of the riverbed at that location and is used to generate a topographic map of the riverbed.

[0110] Specifically, this includes: Step a: Obtaining the water surface elevation corresponding to the point on the waterfront; Step b: Obtain the riverbed elevation of the echo point; Step c: Subtract the riverbed elevation from the water surface elevation to obtain the water depth at the echo point.

[0111] The locations at the bottom of the river channel are the spatial locations corresponding to the beam echo points at the bottom of the river channel. The water depth values ​​are arranged according to spatial distribution to reflect the topographic undulations of the bottom of the river channel.

[0112] The preset selection rules are based on the shoreline orientation in the shoreline geometric constraints. The shoreline outline point sequence is pre-set with the shoreline orientation as the reference and the junction of the riverbank and the water surface as the selection condition. The shoreline points that match the corrected shoreline orientation and are located at the water-land junction are selected as shoreline points, while the shoreline points that do not match the corrected shoreline orientation or are located on pure water or pure land are excluded.

[0113] Furthermore, sonar depth data is extracted from the sensor fusion data, and the beam slant range value of each beam is read one by one according to the arrangement order of the beams in the sonar depth data. The beam slant range value represents the slant distance that the sound wave travels from the sonar transducer to the bottom of the river and is reflected back.

[0114] While reading the beam slant range value, the corresponding beam emission angle is read, and the roll angle and pitch angle in the carrier's corrected pose information are also read.

[0115] The beam emission angle represents the angle at which the beam is emitted from the sonar device in its own reference direction; the roll angle represents the angle at which the carrier tilts left and right around its longitudinal axis; and the pitch angle represents the angle at which the carrier tilts forward and backward around its transverse axis.

[0116] By combining the beam emission angle with the roll angle and pitch angle, the actual direction of the beam in the river channel is obtained. This actual direction can reflect the change in beam direction caused by water surface fluctuations, turns, acceleration and deceleration, or attitude changes of the carrier in the river channel.

[0117] Then, taking the position of the sonar transducer determined by the carrier's corrected pose information as the starting point, the beam slant range value is extended towards the bottom of the river along the actual direction. The position where the beam intersects with the bottom of the river forms an echo point. The above reading and extension operations are performed on all beams to obtain echo points distributed at various locations on the bottom of the river.

[0118] Next, based on the shoreline orientation in the shoreline geometric constraints, the shoreline point located at the junction of the riverbank and the water surface is found in the shoreline outline point sequence, and the found shoreline point is taken as the waterfront point.

[0119] When searching, the shoreline direction is used as a guide. Shoreline points that conform to the shoreline direction and are located at the water-land interface are retained, while shoreline points that deviate from the shoreline direction or are located on pure water or pure land are excluded.

[0120] Then, using the vertical height of the point on the waterline as the starting plane, the vertical distance from the starting plane to each echo point is determined, and this vertical distance is taken as the water depth value at the bottom of the river at that echo point.

[0121] The water depth is determined for all echo points in this manner to obtain the water depth at each location on the bottom of the river.

[0122] These water depth values ​​are arranged according to the spatial location of the echo points, reflecting the topographic undulations of the riverbed and providing a basis for the subsequent generation of riverbed topographic maps.

[0123] In this embodiment, the step of determining the topographic relief features of the riverbed based on the spatial distribution of the water depth values, and associating the topographic relief features with the carrier's corrected pose information to generate a riverbed topographic map includes: By comparing adjacent spatial distributions of the water depth values ​​based on the known spacing of the beam footprints in the sonar bathymetry data, the topographic abrupt boundary at the bottom of the river channel is obtained. The riverbed is categorized by the angle between the abrupt change boundary and the direction of the shoreline, thus obtaining the topographic undulation characteristics of the riverbed. Using the deep trench orientation of the terrain undulation features as a reference, the deviation of the carrier's corrected pose information is compared to obtain the pose deviation of the carrier's corrected pose information. The carrier's corrected pose information is reverse-corrected according to the pose deviation to obtain a matching pose associated with the terrain undulation features and the carrier's corrected pose information. The spatial distribution of the water depth values ​​is sequentially spread out using the matching pose to obtain a topographic map of the riverbed where the map boundary of the riverbed coincides with the sequence of shoreline contour points.

[0124] Specifically, a beam footprint is a finite area formed when a single beam emitted by a sonar transducer illuminates the bottom of a river. The center of this area corresponds to the echo point, and the beam footprint is distributed on the bottom of the river according to the beam alignment direction.

[0125] The known spacing is the distance between the centers of adjacent beam footprints in sonar bathymetry data. This spacing is determined by the beam arrangement, beam emission angle, and transducer installation structure of the sonar transducer. In the bathymetry data, it is used as a known quantity to compare the water depth changes at adjacent locations.

[0126] The spatial distribution of water depth values ​​is the data distribution formed by arranging the water depth values ​​of each echo point at the bottom of the river according to the position of the echo point in the river space, including the distribution along the extension direction of the river and the distribution along the transverse direction of the river.

[0127] The topographic abrupt change boundary is a boundary formed by connecting adjacent water depth values ​​in the spatial distribution of water depth values ​​where the change exceeds the allowable range of natural continuous changes in the riverbed. It indicates locations such as abrupt changes in riverbed slope, deep channel edges, shallow shoal edges, or bank slope toes. Its preset rule is based on whether the change in water depth value within the known distance between adjacent beam footprints exceeds the allowable range of natural continuous changes in the riverbed. This allowable range is determined based on the beam footprint distance and the continuous slope conditions of the riverbed.

[0128] The angle between the direction of the abrupt change in topography and the direction of the shoreline is used to determine whether the abrupt change in topography at the bottom of the river extends along the shoreline or intersects it obliquely or transversely.

[0129] The riverbed is the area below the water surface and between the two banks, including deep channels, shallows, bank slopes, and undulating terrain.

[0130] Orientation classification is based on the angle between the topographic change boundary and the shoreline orientation, classifying the topographic change boundary of the corresponding area at the bottom of the river into categories such as along the bank, oblique, or transverse, in order to obtain the topographic undulation characteristics of the riverbed.

[0131] The topographic relief features are the undulating shapes of the riverbed, consisting of deep channels, shallow shoals, bank slopes, and abrupt topographic boundaries. These features are determined by the spatial distribution of water depth values ​​and the orientation of abrupt topographic boundaries.

[0132] The direction of the deep channel is the direction in which the area with the greatest water depth at the bottom of the river extends continuously, indicating the overall orientation of the deepest part of the river bottom extending along the river channel.

[0133] Deviation comparison uses the orientation of the deep channel in the topographic relief features as a benchmark. The carrier heading and position indicated by the carrier's corrected pose information are compared with the orientation of the deep channel segment by segment to determine whether the carrier's corrected pose information is consistent with the orientation of the riverbed topography.

[0134] Position deviation is the deviation between the direction of the deep channel and the heading or position indicated by the carrier's corrected position information. It includes angular deviation and position deviation. The preset rule is that when the deviation between the direction of the deep channel and the heading of the carrier exceeds the allowable range of the direction, it is determined that there is a position deviation in the carrier's corrected position information. The allowable range of the direction is determined according to the degree of river curvature and the geometric constraints of the shoreline.

[0135] The matching pose is the pose obtained by reverse correction of the carrier's corrected pose information according to the pose deviation. This pose makes the terrain undulation features correspond to the carrier's corrected pose information under the same spatial reference.

[0136] Position deviation and matching pose specifically include: Step a: Obtain the direction of deep channels in the terrain undulation features; Step b: Compare the heading indicated by the carrier's corrected pose information with the direction of the deep trench to obtain the heading deviation; Step c: Compare the position indicated by the carrier's corrected pose information with the center line of the deep trench to obtain the lateral position deviation; Step d: Use the heading deviation and lateral position deviation as pose deviations; Step e: Correct the carrier's pose information in the opposite direction of the pose deviation to obtain a matching pose.

[0137] Sequential deployment uses the alignment of positions as the basis for spatial arrangement. The water depth values ​​of each echo point at the bottom of the river are placed one by one in the corresponding position on the map sheet according to the direction of river extension and the transverse direction of the river, so that the water depth values ​​form continuous topographic map data.

[0138] The map boundary is the boundary of the area covered by the topographic map at the bottom of the river channel. If this boundary coincides with the sequence of shoreline contour points, it means that the outer boundary of the topographic map fits the left and right shoreline contour points.

[0139] A riverbed topographic map is a map obtained by sequentially unfolding the spatial distribution of water depth values ​​according to the pose. Its map boundary coincides with the sequence of shoreline outline points and is used to reflect the topographic undulations of the riverbed.

[0140] Furthermore, in a river environment, as the carrier navigates along the river, the sonar transducer continuously emits beams towards the riverbed and receives echoes. The sonar depth data in the sensor fusion data records the beam slant range, beam emission angle, and beam footprint position of each beam. First, based on the beam arrangement and installation structure of the sonar transducer, the known spacing between adjacent beam footprints is extracted.

[0141] Then, following the known interval, the water depth values ​​at adjacent beam footprints are read one by one along the transverse direction of the river channel and along its extension. During the reading, the vertical height of the waterline point is used as the starting point to determine the water depth value at the bottom of the river channel at each echo point. Subsequently, the magnitude and direction of change of adjacent water depth values ​​are compared to determine whether the water depth values ​​between adjacent beam footprints are continuously increasing, continuously decreasing, or remaining stable.

[0142] When the spacing between adjacent beam footprints is small, and the difference in water depth is greater than the difference allowed by the continuous slope change of the riverbed, it indicates that there is a sudden change in slope, deep channel edge, shallow beach edge, or bank slope toe at that location. Record these locations and connect them along the direction of river extension to form the boundary of the topographic change of the riverbed.

[0143] Next, the angle between the extension direction of the topographic change boundary and the direction of the shoreline is compared. According to the size of the angle, the corresponding area of ​​the river bottom is classified into the direction along the bank, the oblique direction, or the transverse direction, so as to obtain the topographic undulation characteristics of the river bottom.

[0144] Then, taking the direction of the deep trough in the terrain undulation features as a reference, the heading and position indicated by the carrier's corrected pose information are compared with the direction of the deep trough segment by segment. The angular difference between the carrier's heading and the direction of the deep trough, as well as the lateral difference between the carrier's position and the center line of the deep trough, are compared to obtain the pose deviation of the carrier's corrected pose information.

[0145] Then, the carrier's corrected pose information is reversed in the opposite direction of the pose deviation, so that the terrain undulation features and the carrier's corrected pose information correspond to each other under the same spatial reference, thus obtaining a matching pose.

[0146] Finally, based on the matching pose, the water depth values ​​of each echo point at the bottom of the river are laid out one by one in the order of the river direction and the lateral direction, so that the boundary of the map sheet after the laying out coincides with the sequence of shoreline outline points, thus generating a topographic map of the bottom of the river.

[0147] The resulting riverbed topographic map reflects both the changes in riverbed depth and is consistent with the shoreline position and the orientation of the carrier.

[0148] S5: Construct the shoreline contour point sequence into a shoreline layer map, construct the riverbed topographic map into a water depth layer map, determine the spatial correspondence between the shoreline layer map and the water depth map based on the carrier correction pose information, perform spatial association fusion, and generate a multi-layer fused map of the river environment. In this embodiment, constructing the shoreline contour point sequence into a shoreline layer map and constructing the riverbed topographic map into a water depth layer map includes: According to the orientation of the carrier indicated by the carrier correction pose information, the shoreline contour point sequence is divided into columns to obtain the left shoreline elements and right shoreline elements of the shoreline contour point sequence. Along the direction of travel indicated by the carrier's corrected pose information, the left bank shoreline elements and the right bank shoreline elements are assigned numbers one by one, and the left bank shoreline elements and the right bank shoreline elements are combined in sequence to obtain a shoreline layer map. Starting from the left bank shoreline elements and the right bank shoreline elements, the water depth value at the bank of the river bottom topographic map is reset to zero to obtain the bank slope section. By performing deep channel demarcation on the riverbed topographic map along the bank slope and the water depth value, a water depth map is obtained.

[0149] Specifically, the carrier orientation is the direction of the carrier's longitudinal axis in the horizontal plane as indicated by the carrier's corrected pose information. It reflects the direction of the carrier's bow in the river environment and is used to distinguish the shoreline points on the left and the shoreline points on the right in the shoreline contour point sequence with the carrier as a reference.

[0150] The right bank shoreline element is the set of shoreline contour points located on the right side of the carrier in the shoreline contour point sequence. It represents the boundary position and extension direction at the water-land junction on the right bank of the river channel and is used in conjunction with the left bank shoreline element to determine the changes in river width.

[0151] The direction of travel is the direction in which the carrier travels forward along the river, as indicated by the carrier's corrected pose information. It is used to determine the order of the left bank shoreline elements and the right bank shoreline elements along the river's extension direction.

[0152] Assigning numbers to each point is an operation that assigns sequential numbers to each shoreline contour point in the left shoreline element and each shoreline contour point in the right shoreline element according to the direction of travel indicated by the carrier's corrected pose information, in the order of their movement along the river. This operation makes the left and right shoreline contour points correspond to each other at the same location along the river.

[0153] Sequential combination is an operation that arranges and combines the left bank shoreline elements with the right bank shoreline elements one by one according to the order relationship formed by assigning numbers to each location. This operation makes the boundaries of the two banks of the river correspond to each other at the same riverside location, thus forming a shoreline layer map.

[0154] The shoreline layer map is a layer constructed from a sequence of shoreline outline points, representing the location, direction of extension, and width changes of the river's two banks. It includes left bank shoreline elements and right bank shoreline elements, and is used for spatial correlation and fusion with the water depth layer map.

[0155] The area near the bank is the region near the water-land boundary close to the left and right bank shoreline elements on the riverbed topographic map. Physically, this area corresponds to the position where the bank slope meets the water surface and transitions towards the riverbed.

[0156] The bank slope area is the bank slope region obtained by setting the water depth value at the bank near the river bottom topographic map to zero, starting from the left bank shoreline elements and the right bank shoreline elements. It represents the sloping area that transitions from the shoreline to the deep channel at the bottom of the river.

[0157] The deep channel demarcation is an operation that divides the riverbed topographic map along the bank slope section and the water depth value and determines the boundary and range of the deep channel. This operation takes the bank slope section as the starting point and the water depth value gradually increases from zero along the transverse direction of the river to the position of the deep channel boundary as the demarcation basis.

[0158] The water depth map is a layer obtained by defining the bottom topographic map of the river channel along the bank slope and the water depth value, which represents the water depth distribution and the direction of the deep channel. It is used to spatially correlate and fuse with the shoreline layer map to generate a multi-layer fused map of the river environment.

[0159] Furthermore, in the river environment, the carrier travels along the river, and multi-source sensors collect multi-source sensor data in the river environment. The multi-source sensor data is synchronized in time and registered in space to generate sensor fusion data. The river shoreline contour features are extracted from the sensor fusion data and a shoreline contour point sequence is generated.

[0160] Inertial measurement data is extracted from sensor fusion data. The direction of motion of the carrier is determined based on the heading angle and the geometric constraint relationship of the shoreline in the inertial measurement data. When the direction of motion deviates from the shoreline, the direction of motion is corrected according to the geometric constraint relationship of the shoreline to generate the corrected pose information of the carrier.

[0161] Using the orientation of the carrier indicated by the carrier's corrected pose information as a reference, the shoreline contour points located on the port side of the carrier in the shoreline contour point sequence are assigned to the port shoreline elements, and the shoreline contour points located on the starboard side of the carrier are assigned to the starboard shoreline elements, thus completing the sorting of the shoreline contour point sequence.

[0162] Then, using the direction of travel indicated by the carrier's corrected pose information as the sequential reference, each shoreline contour point in the left bank shoreline element is sequentially assigned a left bank number along the river extension direction, and each shoreline contour point in the right bank shoreline element is sequentially assigned a right bank number, so that the left bank shoreline elements and the right bank shoreline elements form a corresponding relationship at the same riverside location.

[0163] Then, the left bank shoreline elements and right bank shoreline elements are combined and arranged one by one according to the numbering order to form a shoreline layer map that represents the location, extension direction and width changes of the river's two sides.

[0164] After obtaining water depth values ​​at various locations on the riverbed using sonar bathymetry data and determining the topographic undulations of the riverbed based on the spatial distribution of water depth values, a riverbed topographic map is generated. Starting from the locations of the left and right bank shoreline elements, the water depth values ​​at the riverbed topographic map near the bank are searched towards the center of the river. The water depth values ​​at the bank are then set to zero, resulting in the bank slope section that transitions from the shoreline to the deep channel at the riverbed.

[0165] Then, compare the changes in water depth along the bank slope towards the center of the river channel. The position where the water depth gradually increases from zero and reaches the deep channel boundary is determined as the deep channel boundary. The deep channel boundary is then used to demarcate the river bottom topography map along the deep channel boundary, resulting in a water depth layer map that represents the water depth distribution and direction of the deep channel at the bottom of the river.

[0166] In this embodiment, determining the spatial correspondence between the shoreline layer map and the water depth layer map based on the carrier-corrected pose information, performing spatial correlation fusion, and generating a multi-layer fused map of the river environment includes:

[0167] Based on the carrier's corrected pose information, the shoreline layer map and the water depth layer map are paired position by position to determine their spatial correspondence. Based on the spatial correspondence and the water depth value, the water boundary is identified in the water depth map; By cross-referencing the waterfront boundary with the shoreline contour point sequence, the shoreline water depth correlation zone in the spatial correspondence is obtained; Based on the shoreline water depth correlation zone, the shoreline layer map and the water depth layer map are spatially correlated and fused to obtain the spatial correlation fusion result; Based on the spatial correlation fusion result and the geometric constraint relationship of the shoreline, the shoreline contour point sequence is selected and discarded to generate a multi-level fused map of the river environment.

[0168] Specifically, position-by-position pairing is an operation that, based on the carrier position, carrier orientation, corrected heading angle, pitch angle, and roll angle indicated by the carrier's corrected pose information, establishes a one-to-one correspondence between the shoreline contour points in the shoreline layer map and the riverbed positions in the depth layer map, according to the same riverside position and the same lateral position.

[0169] Spatial correspondence is the coordinate correspondence between the shoreline layer map and the depth layer map, determined by pairing them position by position, in the river-direction, lateral direction, and vertical reference. This relationship is used to ensure that the shoreline position in the shoreline layer map and the water depth distribution in the depth layer map are on the same spatial reference.

[0170] A water boundary is a boundary between land and water, or a boundary where the water depth transitions from zero to a positive value, identified in a depth map based on spatial correspondence and water depth values. This boundary represents the water-adjacent location between a bank slope and a deep channel or water-covered area.

[0171] Cross-checking is a check that compares the position of the waterfront boundary with the position of each shoreline point in the shoreline contour point sequence to determine whether they match. This operation compares the positional differences between the waterfront boundary and the shoreline contour points segment by segment along the shoreline and determines the correlation between them.

[0172] The shoreline-depth correlation zone is the area where the shoreline location and water depth distribution are correlated, determined through spatial correspondence after cross-referencing the sequence of shoreline contour points with the shoreline boundary. This zone represents the range within which the shoreline location in the shoreline layer map and the water depth value in the depth layer map can correspond to each other.

[0173] Spatial correlation fusion is an operation that merges shoreline layer maps and water depth layer maps into a unified map under the same spatial reference, based on the shoreline-water depth correlation zone. This operation uses the shoreline-water depth correlation zone as a common reference and overlays shoreline contour points and water depth values ​​point by point along the river and laterally.

[0174] The spatial correlation fusion result is a unified dataset containing shoreline boundaries and water depth distribution, obtained by spatially correlating and fusing shoreline layer maps and depth layers. This result is used in conjunction with shoreline geometric constraints to select and discard shoreline contour point sequences.

[0175] The multi-layered fusion map of the river environment is a unified map containing both the shoreline layer and the water depth layer, generated by selecting shoreline contour point sequences based on spatial correlation fusion results and shoreline geometric constraints. This map is used for real-time location updates of the carrier.

[0176] Furthermore, when the carrier's corrected attitude information is used to pair the shoreline layer map with the water depth map point by point, the corrected heading angle in the carrier's corrected attitude information is first used to determine the carrier's direction of travel along the river, and the pitch angle and roll angle are used to determine the carrier's attitude reference. Then, the left bank shoreline elements and right bank shoreline elements in the shoreline layer map are arranged point by point along the shoreline direction using this attitude reference.

[0177] At the same time, the deep channel boundaries and water depth values ​​in the water depth map are arranged point by point according to the same riverside position and the same lateral position, so that each shoreline point in the shoreline layer map is associated with the corresponding water depth value in the water depth map, thereby determining the spatial correspondence between the two.

[0178] Then, based on the spatial correspondence and water depth values, the locations where the water depth values ​​transition from zero to positive values ​​and the water-land interface locations are found in the water depth map, and the consecutively arranged locations are connected to form the water boundary.

[0179] Next, the sequence of waterfront boundary and shoreline outline points is cross-checked. The positional differences between the waterfront boundary and shoreline outline points are compared segment by segment along the shoreline. Shoreline outline points with consistent positions or positional differences within the allowable range of continuous shoreline extension are retained. The shoreline points and waterfront boundary segments with correlation are marked to obtain the shoreline water depth correlation zone in the spatial correspondence.

[0180] Then, based on the shoreline-water-depth correlation zone, the shoreline layer map and the water depth layer map are spatially correlated and fused. Using the shoreline-water-depth correlation zone as a common benchmark, the shoreline contour points in the shoreline layer map and the water depth values ​​in the water depth layer map are superimposed one by one along the river direction and the lateral direction, so that the shoreline position and the water depth distribution correspond under the same coordinate, and the spatial correlation and fusion result is obtained.

[0181] Finally, based on the spatial correlation fusion results and the geometric constraints of the shoreline, the shoreline contour point sequence is selected. The shoreline contour points that are consistent with the corrected shoreline direction, the water boundary, and the trend of shoreline spacing change are retained, while the shoreline contour points that deviate from the corrected shoreline direction or contradict the water depth distribution are removed. The retained shoreline contour points are then combined with the spatial correlation fusion results in sequence to generate a multi-level fusion map of the river environment.

[0182] S6: Based on the multi-layer fusion map of the river environment, the position of the carrier is updated in real time to generate real-time location information.

[0183] In this embodiment, the multi-layered fusion map based on the river environment is used to update the location of the carrier in real time, generating real-time location information, including: The shoreline contour point sequence is projected onto the shoreline layer map and compared with the left and right shoreline point sequences along the shoreline direction to obtain the lateral offset in the position of the carrier. Based on the lateral offset and the trend of the shoreline spacing change, the shoreline spacing is compared segment by segment to obtain the equal-width segments in the shoreline layer map; By comparing the water depth distribution of the riverbed topographic map and the water depth map within the equal width section, the shoreline offset in the water depth map is obtained. The coastal offset is verified using the motion direction and the shoreline geometric constraint relationship to obtain the position update result of the carrier. Based on the multi-layered fused map and the location update results, the location of the carrier is updated in real time to generate real-time location information.

[0184] Specifically, the left and right shoreline point sequence is a point sequence formed by separating the left and right shoreline points according to the orientation of the carrier in the shoreline outline point sequence, arranged along the direction of river extension. It is used to determine the position of the left and right shorelines and to make lateral comparisons in the shoreline layer map.

[0185] The shoreline orientation is the direction of shoreline extension on both sides of the river channel identified by adjacent shoreline contour points in the shoreline contour point sequence. The left bank shoreline orientation and the right bank shoreline orientation represent the local orientation of the left and right banks in the direction of river channel extension, respectively.

[0186] The location of a carrier is its spatial position relative to the shoreline layer map and the multi-layer fused map within the river environment, including its position along the river's extension direction and its lateral position perpendicular to the shoreline direction.

[0187] Lateral offset is the deviation of the carrier's position in the direction perpendicular to the shoreline direction, obtained by projecting the shoreline contour point sequence onto the shoreline layer map and comparing it with the left and right shoreline point sequences along the shoreline direction. It represents the degree to which the carrier deviates from the river center or corresponding shoreline position defined by the left and right shorelines. Specifically, it includes: Step a: Projecting the shoreline contour points onto the shoreline layer map; Step b: Calculate the vertical distance from the projection point to the sequence of points on the left shoreline to obtain the left distance; Step c: Calculate the perpendicular distance from the projection point to the sequence of points on the right shoreline to obtain the right distance; Step d: Divide the difference between the right distance and the left distance by two to obtain the lateral offset.

[0188] The distance between the two banks is the lateral distance between the left bank shoreline elements and the right bank shoreline elements at the same riverside location or corresponding number in the shoreline layer map. It is used to determine whether the river channel is widening, narrowing, or approximately equal in width.

[0189] Equal width sections are sections in the shoreline layer map where the distance between the left and right shorelines remains stable or is within the allowable range of continuous shoreline changes, after comparing the distance between the two shorelines segment by segment based on the trend of the change in the lateral offset and the distance between the shorelines. This allowable range is determined based on the trend of continuous shoreline changes and the change in river width. When there is no sudden change in the distance between the left and right shorelines within the continuous section that exceeds this allowable range, it is classified as an equal width section.

[0190] Water depth distribution is the data distribution formed by arranging the water depth values ​​of each echo point at the bottom of the river according to the position of the echo points in the river space, including the distribution along the extension direction of the river and the distribution along the transverse direction of the river.

[0191] The offset along the riverbank is the amount of displacement along the river's extension direction in the water depth map obtained by comparing the water depth distribution of the riverbed topographic map and the water depth map within the equal width section. It represents the deviation of the carrier's position in the riverside direction.

[0192] The position update result is the carrier position correction result obtained after verifying the offset along the shoreline based on the direction of movement and the geometric constraints of the shoreline. It is used for real-time positioning and updating of the carrier position.

[0193] Real-time location updates are operations that continuously correct the position of the carrier based on multi-layered fused maps and location update results, and output the current position.

[0194] Real-time location information is the current location information of the carrier in the river environment, generated after the carrier's position is updated in real time.

[0195] Furthermore, the sequence of shoreline outline points is projected onto the shoreline layer map according to the established spatial correspondence, so that the shoreline outline points and the left and right shoreline elements in the shoreline layer map are classified into the same riverside location and the same lateral reference.

[0196] Subsequently, the projected shoreline contour point sequence is compared point by point with the left and right shoreline point sequences along the shoreline direction to obtain the lateral deviation of the carrier position relative to the left and right shorelines, forming the lateral offset.

[0197] Then, based on the trend of lateral offset and shoreline spacing, the distance between the left and right shoreline elements is read segment by segment along the river channel extension direction. Continuous segments where the distance between the two shorelines remains stable or within the allowable range of continuous variation determined by the shoreline orientation and the trend of shoreline spacing are identified as equal-width segments.

[0198] Within the equal-width section, the water depth distribution on the riverbed topographic map is compared with the water depth distribution on the water depth layer map at the same riverside location and the same lateral location to determine the amount of displacement of the water depth distribution along the river's extension direction, thus obtaining the amount of offset along the bank.

[0199] The offset along the river is then verified by the relationship between the direction of movement and the geometric constraints of the shoreline. Reasonable offsets caused by the natural turning of the river channel and the turning of the shoreline are excluded. The offset along the river that needs to be corrected is retained and combined with the lateral offset to obtain the position update result of the carrier.

[0200] Finally, using a multi-layered fused map as the spatial reference, the location update results are continuously associated with the carrier's previous location, and the carrier's location is updated in real time, outputting the carrier's current real-time location information in the river environment.

[0201] like Figure 2 The diagram shown is a functional block diagram of a river environment synchronous positioning and mapping system based on multi-sensor fusion provided in an embodiment of the present invention.

[0202] The river environment synchronous positioning and mapping system 100 based on multi-sensor fusion described in this invention can be installed in an electronic device. Depending on the functions implemented, the river environment synchronous positioning and mapping system 100 may include a synchronous registration module 101, a feature extraction module 102, a pose correction module 103, a terrain construction module 104, a map fusion module 105, and a positioning update module 106. The modules described in this invention can also be referred to as units, which are a series of computer program segments that can be executed by the processor of an electronic device and can perform a fixed function, and are stored in the memory of the electronic device.

[0203] In this embodiment, the functions of each module / unit are as follows: Synchronization and registration module 101: Utilizes a carrier equipped with multi-source sensors to collect multi-source sensor data in the river environment, and performs time synchronization and spatial registration on the multi-source sensor data to generate sensor fusion data; Feature extraction module 102: Extracts riverbank contour features from the sensor fusion data, generates a shoreline contour point sequence, and extracts inertial measurement data from the sensor fusion data; Pose correction module 103: Based on the shoreline contour point sequence, it identifies the shoreline direction and shoreline spacing change trend on both sides of the river, generates shoreline geometric constraint relationship, determines the motion direction of the carrier according to the inertial measurement data, and when the motion direction deviates from the shoreline direction, it corrects the motion direction according to the shoreline geometric constraint relationship to generate carrier corrected pose information. Terrain construction module 104: Using sonar depth data from the sensor fusion data, it obtains water depth values ​​at various locations on the bottom of the river, determines the topographic undulation features of the river bottom based on the spatial distribution of the water depth values, and associates the topographic undulation features with the carrier's corrected pose information to generate a topographic map of the river bottom. Map fusion module 105: Constructs the shoreline contour point sequence into a shoreline layer map, constructs the riverbed topographic map into a water depth layer map, determines the spatial correspondence between the shoreline layer map and the water depth layer map based on the carrier correction pose information, performs spatial association fusion, and generates a multi-layer fused map of the river environment. Location update module 106: Based on the multi-layer fusion map of the river environment, the location of the carrier is updated in real time to generate real-time location information.

[0204] The synchronous registration module, feature extraction module, pose correction module, terrain construction module, map fusion module, and positioning update module are sequentially connected for data transfer. The synchronous registration module outputs sensor fusion data to the feature extraction module. The feature extraction module outputs shoreline contour point sequences and inertial measurement data to the pose correction module. The pose correction module outputs carrier-corrected pose information to the terrain construction module and the map fusion module. The terrain construction module outputs a riverbed topographic map to the map fusion module. The map fusion module outputs a multi-layered fused map to the positioning update module.

[0205] In the several embodiments provided by this invention, it should be understood that the disclosed methods and systems can be implemented in other ways. For example, the system embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and other division methods may be used in actual implementation.

[0206] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0207] Furthermore, the functional modules in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or in the form of hardware plus software functional modules.

[0208] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0209] The embodiments of this application can acquire and process relevant data based on artificial intelligence technology. Artificial intelligence is the theory, method, technology, and application system that uses digital computers or machines controlled by digital computers to simulate, extend, and expand human intelligence, perceive the environment, acquire knowledge, and use that knowledge to obtain optimal results.

[0210] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A river environment simultaneous localization and mapping method based on multi-sensor fusion, characterized in that, The method includes: S1: Using a carrier equipped with multi-source sensors, collect multi-source sensor data in the river environment, and perform time synchronization and spatial registration on the multi-source sensor data to generate sensor fusion data; S2: Extract riverbank contour features from the sensor fusion data, generate a shoreline contour point sequence, and extract inertial measurement data from the sensor fusion data; S3: Based on the shoreline contour point sequence, identify the shoreline direction and shoreline spacing change trend on both sides of the river, generate shoreline geometric constraint relationship, determine the motion direction of the carrier according to the inertial measurement data, and when the motion direction deviates from the shoreline direction, correct the motion direction according to the shoreline geometric constraint relationship to generate carrier correction pose information; S4: Using the sonar depth data in the sensor fusion data, obtain the water depth values ​​at various locations on the bottom of the river. Determine the topographic undulation features of the bottom of the river based on the spatial distribution of the water depth values. Associate the topographic undulation features with the carrier's corrected pose information to generate a topographic map of the bottom of the river. S5: Construct the shoreline contour point sequence into a shoreline layer map, construct the riverbed topographic map into a water depth layer map, determine the spatial correspondence between the shoreline layer map and the water depth map based on the carrier correction pose information, perform spatial association fusion, and generate a multi-layer fused map of the river environment. S6: Based on the multi-layer fusion map of the river environment, the position of the carrier is updated in real time to generate real-time location information.

2. The river environment simultaneous localization and mapping method based on multi-sensor fusion of claim 1, wherein, The step of performing time synchronization and spatial registration of the multi-source sensor data to generate sensor fusion data includes: The cross section of the river channel is calibrated using the acquisition time and heading data from the multi-source sensor data, and the multi-source sensor data is merged into the cross section of the river channel to obtain time synchronization data. Based on the time synchronization data, the sonar depth data in the multi-source sensor data is corrected to the water surface elevation in the multi-source sensor data to obtain the vertical position assignment; Under the given vertical position assignment, the two ends of the water surface span and the depth measurement span in the multi-source sensor data are relatively coincided to obtain the lateral reference; Based on the vertical position attribution and the lateral reference, spatial registration is performed on the observation data from each source sensor in the multi-source sensor data to obtain the sensor fusion data.

3. The river environment simultaneous localization and mapping method based on multi-sensor fusion of claim 1, wherein, The step of identifying the shoreline orientation and spacing trends on both sides of the river based on the shoreline contour point sequence, and generating shoreline geometric constraints, includes: Based on adjacent shoreline contour points in the shoreline contour point sequence, the shoreline orientation on both sides of the river channel is identified. By combining the orientation of the shorelines on both sides of the river channel and comparing the distance between paired shoreline contour points in the shoreline contour point sequence, the trend of the change in the shoreline spacing on both sides of the river channel can be identified. The trend of the distance between the banks of the river is used to verify the orientation of the banks of the river, and the corrected orientation of the banks is obtained. Remove shoreline contour points from the shoreline contour point sequence that do not match the corrected shoreline direction to obtain matching shoreline contour points; The riverbanks are constrained by the matching shoreline contour points and the trend of shoreline spacing changes, thus generating a shoreline geometric constraint relationship.

4. The river environment simultaneous localization and mapping method based on multi-sensor fusion of claim 1, wherein, The step of determining the motion direction of the carrier based on the inertial measurement data, and correcting the motion direction according to the geometric constraints of the shoreline when the motion direction deviates from the shoreline direction to generate carrier corrected pose information, includes: The direction of motion of the carrier is determined based on the relationship between the heading angle in the inertial measurement data and the geometric constraints of the shoreline; By comparing the direction of motion with the direction of the shoreline, the heading deviation of the direction of motion relative to the direction of the shoreline is obtained; Check the turning point of the course deviation and the shoreline direction along the trend of the shoreline spacing change, and mark the river channel turning deviation that follows the shoreline turning. After excluding the river channel turning deviation, the heading deviation that deviates from the shoreline direction is identified based on the shoreline geometric constraints. Based on the heading drift deviation and the river course turning deviation, the motion direction is corrected to generate carrier corrected pose information.

5. The river environment simultaneous localization and mapping method based on multi-sensor fusion of claim 1, wherein, The step of using sonar depth data from the sensor fusion data to obtain water depth values ​​at various locations on the riverbed includes: Using the sonar depth data in the sensor fusion data, the beam slant range value of each beam is extracted; Based on the beam emission angle in the sonar depth sounding data and the roll and pitch angles in the carrier's corrected pose information, the actual direction of each beam is restored. Starting from the position of the sonar transducer determined by the carrier's corrected pose information, the beam slant range value is extended along the actual direction to obtain the echo point at the bottom of the river channel. Based on the shoreline orientation in the shoreline geometric constraint relationship, shoreline points located at the junction of the riverbank and the water surface are selected from the shoreline contour point sequence to obtain the waterfront points; Using the vertical height of the waterline point as the starting point, the water depth values ​​at each location on the bottom of the river channel at the echo point are obtained.

6. The river environment simultaneous localization and mapping method based on multi-sensor fusion of claim 1, wherein, The step of determining the topographic relief features of the riverbed based on the spatial distribution of the water depth values, and associating the topographic relief features with the carrier's corrected pose information to generate a riverbed topographic map includes: By comparing adjacent spatial distributions of the water depth values ​​based on the known spacing of the beam footprints in the sonar bathymetry data, the topographic abrupt boundary at the bottom of the river channel is obtained. The riverbed is categorized by the angle between the abrupt change boundary and the direction of the shoreline, thus obtaining the topographic undulation characteristics of the riverbed. Using the deep trench orientation of the terrain undulation features as a reference, the deviation of the carrier's corrected pose information is compared to obtain the pose deviation of the carrier's corrected pose information. The carrier's corrected pose information is reverse-corrected according to the pose deviation to obtain a matching pose associated with the terrain undulation features and the carrier's corrected pose information. The spatial distribution of the water depth values ​​is sequentially spread out using the matching pose to obtain a topographic map of the riverbed where the map boundary of the riverbed coincides with the sequence of shoreline contour points.

7. The river environment simultaneous localization and mapping method based on multi-sensor fusion of claim 1, wherein, The step of constructing a shoreline layer map from the sequence of shoreline contour points and constructing a depth layer map from the riverbed topographic map includes: According to the orientation of the carrier indicated by the carrier correction pose information, the shoreline contour point sequence is divided into columns to obtain the left shoreline elements and right shoreline elements of the shoreline contour point sequence. Along the direction of travel indicated by the carrier's corrected pose information, the left bank shoreline elements and the right bank shoreline elements are assigned numbers one by one, and the left bank shoreline elements and the right bank shoreline elements are combined in sequence to obtain a shoreline layer map. Starting from the left bank shoreline elements and the right bank shoreline elements, the water depth value at the bank of the river bottom topographic map is reset to zero to obtain the bank slope section. By performing deep channel demarcation on the riverbed topographic map along the bank slope and the water depth value, a water depth map is obtained.

8. The river environment simultaneous localization and mapping method based on multi-sensor fusion of claim 1, wherein, The process of determining the spatial correspondence between the shoreline layer map and the water depth layer map based on the carrier-corrected pose information, performing spatial correlation and fusion, and generating a multi-layered fused map of the river environment includes: Based on the carrier's corrected pose information, the shoreline layer map and the water depth layer map are paired position by position to determine their spatial correspondence. Based on the spatial correspondence and the water depth value, the water boundary is identified in the water depth map; By cross-referencing the waterfront boundary with the shoreline contour point sequence, the shoreline water depth correlation zone in the spatial correspondence is obtained; Based on the shoreline water depth correlation zone, the shoreline layer map and the water depth layer map are spatially correlated and fused to obtain the spatial correlation fusion result; Based on the spatial correlation fusion result and the geometric constraint relationship of the shoreline, the shoreline contour point sequence is selected and discarded to generate a multi-level fused map of the river environment.

9. The river environment simultaneous localization and mapping method based on multi-sensor fusion of claim 1, wherein, The multi-layered fusion map based on the river environment updates the location of the carrier in real time, generating real-time location information, including: The shoreline contour point sequence is projected onto the shoreline layer map and compared with the left and right shoreline point sequences along the shoreline direction to obtain the lateral offset in the position of the carrier. Based on the lateral offset and the trend of the shoreline spacing change, the shoreline spacing is compared segment by segment to obtain the equal-width segments in the shoreline layer map; By comparing the water depth distribution of the riverbed topographic map and the water depth map within the equal width section, the shoreline offset in the water depth map is obtained. The coastal offset is verified using the motion direction and the shoreline geometric constraint relationship to obtain the position update result of the carrier. Based on the multi-layered fused map and the location update results, the location of the carrier is updated in real time to generate real-time location information.

10. A river environment simultaneous localization and mapping system based on multi-sensor fusion, characterized in that, The system includes: Synchronization and registration module: Utilizing a carrier equipped with multi-source sensors, it collects multi-source sensor data in the river environment, performs time synchronization and spatial registration on the multi-source sensor data, and generates sensor fusion data; Feature extraction module: Extracts riverbank contour features from the sensor fusion data, generates a sequence of shoreline contour points, and extracts inertial measurement data from the sensor fusion data; Pose correction module: Based on the shoreline contour point sequence, identify the shoreline direction and shoreline spacing change trend on both sides of the river, generate shoreline geometric constraint relationship, determine the motion direction of the carrier according to the inertial measurement data, and when the motion direction deviates from the shoreline direction, correct the motion direction according to the shoreline geometric constraint relationship to generate carrier corrected pose information; Terrain construction module: Using sonar depth data from the sensor fusion data, the water depth values ​​at various locations on the bottom of the river are obtained. Based on the spatial distribution of the water depth values, the topographic undulation features of the bottom of the river are determined. The topographic undulation features are correlated with the carrier's corrected pose information to generate a topographic map of the bottom of the river. Map fusion module: Constructs the shoreline contour point sequence into a shoreline layer map, constructs the riverbed topographic map into a water depth layer map, determines the spatial correspondence between the shoreline layer map and the water depth map based on the carrier correction pose information, performs spatial association fusion, and generates a multi-layer fused map of the river environment. Location update module: Based on the multi-layer fusion map of the river environment, the location of the carrier is updated in real time to generate real-time location information.

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