Unmanned ship water depth data collection and transmission method and system with position correlation and redundant storage function

Abstract

The application provides a unmanned ship water depth data acquisition and transmission method and system with position correlation and redundant storage function, belongs to the technical field of unmanned ship water depth data transmission, and the system comprises an RTK positioning system, a depth sensor, a data fusion system, a unmanned ship autopilot, a U disk storage, a ground station QGC, a data transmission module interface and a shore-based controller. Through integration of the autopilot module, the GPS positioning unit and the depth sensor, real-time fusion of the water depth data, the current position and the heading information is realized. Meanwhile, the fused data is synchronously transmitted to the shore-based controller for local display and redundant storage in a wireless communication mode such as LoRa. Even in the case of power failure or equipment abnormality, the recorded data can still be completely saved at the shore-based controller end, the reliability of data storage is improved, and through the unmanned plane as a temporary server and through a high-frequency acoustic communication mode, the influence of complex environment can be better overcome.

Description

Technical Field

[0001] This invention relates to the field of unmanned surface vessel (USV) depth data transmission technology, and in particular to a method and system for USV depth data acquisition and transmission with location association and redundant storage functions. Background Technology

[0002] Traditional unmanned surface vessel (USV) bathymetry systems typically acquire water depth data using only a single sensor, lacking real-time correlation with geographic location and heading information. This makes it difficult for operators to intuitively interpret water depth changes within a map environment. Furthermore, existing systems often use the MAVLink protocol to transmit water depth data to a QGroundControl (QGC) ground station for real-time display. However, in cases of network instability or equipment failure (such as power outages or system crashes), data transmission may be interrupted, leading to the loss of historical data and affecting the integrity of the surveying task. Current systems generally lack effective redundant storage mechanisms, failing to guarantee complete data preservation during data transmission interruptions and increasing the risk of data loss.

[0003] In industry applications, a general technical approach for water depth measurement and data transmission of unmanned vessels has been initially established: (1) Using sensor depth measurement: The output water depth value is directly provided to the control system, ground station (QGroundControl, MissionPlanner, etc.), or storage device. This type of solution usually treats water depth data as an independent parameter; it lacks synchronous integration with position and heading data, thereby reducing the spatial interpretability and application depth of the overall data. (2) Relying on a single communication protocol for transmission of depth sensors: The common practice in the industry is to transmit and present water depth data to QGC software through protocols such as MAVLink, NMEA0183, RS-232 / RS-485 to achieve remote monitoring and basic recording. However, the data acquisition and transmission link is still prone to instability under environmental interference, distance limitations, electromagnetic shielding and other factors. Once the transmission is blocked or the link is interrupted, the QGC side often lacks a backup path to acquire the corresponding data, which affects the continuity of real-time monitoring and subsequent analysis. (3) Data storage: At present, most systems concentrate data storage and management functions in a single storage medium inside the ground control terminal or the unmanned vessel. This means that in the event of a power outage, main control system crash, sensor malfunction, or communication link interruption on the unmanned vessel, some or even all of the depth measurement data may not be backed up and saved in time, resulting in the irreversible loss of critical mapping data and causing significant difficulties for subsequent analysis. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for acquiring and transmitting water depth data from unmanned surface vessels with location association and redundant storage functions, thereby solving the technical problems mentioned in the background art.

[0005] The system achieves synchronous acquisition and parsing of multi-source data through three independent serial port channels. During the data acquisition and parsing process, the system introduces a multi-layer logic parsing and data fusion mechanism. When receiving instructions from shore-based controllers or unmanned vessels, the system can flexibly adjust parameters and change states.

[0006] Depth sounder → (serial port 1) → Buffer 1, RTK positioning → (serial port 2) → Buffer 2, Autopilot & control commands → (serial port 3) → Command processing module.

[0007] Data parsing and preprocessing: The parsing module extracts the NMEA field from buffer 1 / 2 → removes outliers → and performs unit conversion.

[0008] Time synchronization and data fusion: timestamp verification → matching depth measurement data and positioning data → generating fused data records.

[0009] Data packaging and transmission: Data frame generation → Adding checksum and frame sequence number → Sending to the autopilot (serial port 3). Autopilot → Wireless module → Shore-based control / Ground station.

[0010] Redundant storage: Data → stored on USB drive → simultaneously sent to QGC for storage in txt text file.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] A method for acquiring and transmitting water depth data from an unmanned surface vessel (USV) with location association and redundant storage capabilities, the method comprising the following steps:

[0013] Step 1: Data acquisition. The depth data from the depth sounder and the positioning information from the RTK positioning device are acquired through the serial port. The acquired data are fused and then transmitted to the unmanned vessel's autopilot to realize the transmission of fused data and the reception of commands.

[0014] Step 2: Data parsing and preprocessing, format parsing of depth sounding and positioning messages, extraction of key fields, conversion of extracted latitude and longitude information from degree-minute format, filtering of abnormal or invalid data, and interpolation repair as needed;

[0015] Step 3: Time synchronization and data fusion. Data synchronization and matching are performed based on timestamps. Etching and positioning data with similar times are bound together to obtain a fused data structure containing location and depth. Data exceeding the time synchronization threshold is processed by waiting, discarding, or interpolation.

[0016] Step 4: Data Packaging and Transmission. The fused data is packaged according to the set protocol format, with frame headers, frame sequence numbers, and checksums added. It is then sent to the unmanned vessel's autopilot via a serial port, and then transmitted to the ground station and shore-based controller via the autopilot's wireless link. The fused data is stored and displayed at the ground station and shore-based controller to achieve real-time monitoring.

[0017] Step 5: Redundant storage and fault response. Real-time or periodic data is packaged and stored locally on the unmanned vessel using storage media. Data received at the shore-based control terminal is also redundantly stored to prevent data loss due to link interruption or equipment failure. When the network is restored or the unmanned vessel returns to shore, the data on the storage media is checked, merged, or updated with the shore-based data.

[0018] Furthermore, the specific process of step 1 is as follows:

[0019] Step 1.1: Read depth sounder data. Listen to the NMEA 0183 format messages output by the depth sounder through the first serial port 1. The messages include three water depth values ​​and check data. Each message received is placed into the depth sounding data circular buffer for subsequent parsing.

[0020] Step 1.2: RTK positioning data reading. Listen for NMEA 0183 messages output by the RTK positioning device through serial port 2. Each received message is placed into the positioning data circular buffer for subsequent parsing.

[0021] Step 1.3: Serial port interface of the autopilot. Communicate with the autopilot of the unmanned vessel through serial port 3, receive control commands sent by the autopilot, including start sampling, stop sampling and change transmission frequency, and package the fused water depth data and positioning data and transmit them to the autopilot.

[0022] Furthermore, the specific process of step 2 is as follows:

[0023] Step 2.1: Split the message fields. Using commas as delimiters or regular expressions, split the NMEA message into independent fields. For GGA messages, extract the fields of time, latitude, longitude, positioning quality, number of satellites, and altitude. For RMC messages, extract the fields of time, positioning status, latitude, longitude, speed, heading, and date. For SDBTT messages, extract the water depth value and its depth unit.

[0024] Step 2.2: Unit and format conversion. Convert latitude and longitude in degree and minute format to decimal format in degrees, and convert the water depth value unit to meters.

[0025] Step 2.3: Handling outliers and missing values. Anomaly detection is performed for cases such as negative water depth values. If outliers are found, they are marked or filtered. Missing water depth values ​​are interpolated before or after the specified values ​​or discarded.

[0026] Furthermore, the specific process of step 3 is as follows:

[0027] Step 3.1: Time synchronization. Establish a unified time reference. Based on the timestamp provided by RTK, compare the timestamps of the water depth data and the positioning data. If the time difference between the two is within ±0.1 seconds, they are considered to correspond to the same time period and can be directly fused. If the difference exceeds the threshold, it is handled as follows: Interpolation strategy: When the interval between the two is greater than the set value, use the aligned data before and after to perform linear interpolation and estimate the mean of the water depth or position at the intermediate time.

[0028] Step 3.2: Data fusion. Bind the time-aligned water depth values ​​with latitude, longitude, altitude and heading to form a new fused data structure, namely timestamp, latitude, longitude, water depth, heading and speed.

[0029] Furthermore, the specific process of step 4 is as follows:

[0030] Step 4.1: Data frame structure design. After fusion, assemble the data frame, data content, fixed characters, frame sequence number and check field according to the custom protocol. The frame header is a fixed byte 0xAA55, which is used to identify the start of data. The data content includes timestamp, latitude, longitude, water depth, heading and speed. The fixed bytes and frame sequence number facilitate the receiver to detect packet loss or out-of-order delivery. The check field is an F* checksum to ensure that the data has not been tampered with or damaged.

[0031] Step 4.2: Serial port parameters and transmission strategy. Select a baud rate that matches the unmanned vessel's autopilot. To ensure real-time performance and stability, use a batch packaging method to package every N data items into a data block and send them together to reduce transmission overhead.

[0032] Step 4.3: Receiver processing. After receiving the data, the autopilot forwards the data to the ground station and shore-based controller via the built-in or external wireless communication module. The ground station and shore-based controller display the ship's position, heading, and water depth curve in real time, and store the data locally.

[0033] Furthermore, the specific process of step 5 is as follows:

[0034] Step 5.1: Local storage on USB flash drive. After the data is generated or processed, the unmanned vessel periodically writes the data to the USB flash drive for segmented storage. Every 10 minutes or when the data volume reaches a threshold, a new file is created to prevent a single file from exceeding the set value. Verification and breakpoint continuation are performed. After the writing is completed, the file is verified. If the power is lost in the middle, it will be detected and resumed after the next power-on.

[0035] Step 5.2: Shore-based redundant storage. After receiving data, the shore-based controller synchronously writes it to a USB flash drive to form another backup. This creates a primary and backup storage method with the QGC ground station to prevent data loss or errors due to the failure of a single device.

[0036] Furthermore, in step 5, the unmanned surface vessel (USV) is equipped with a high-frequency acoustic transmitter. When the USV loses communication with the ground station and shore-based controller, the high-frequency acoustic transmitter on the USV initiates a communication attempt. The ground station is equipped with a relay drone, which carries a high-frequency acoustic receiver. When the ground station and shore-based controller lose communication with the USV, the relay drone is launched and flies to the latitude and longitude of the USV last received by the ground station. It then establishes high-frequency acoustic communication with the USV until communication between the USV and the ground station and shore-based controller is restored, or until staff determine the specific location of the USV and manually control the relay drone to fly back. This effectively avoids the problems of the USV losing contact and being difficult to locate.

[0037] A system for acquiring and transmitting water depth data from an unmanned surface vessel (USV) with location association and redundant storage functions includes an RTK positioning system, a depth sounding sensor, a data fusion system, an USV autopilot, a USB flash drive, a ground station QGC, a data transmission module interface, and a shore-based controller. The RTK positioning system and the depth sounding sensor are both connected to the data fusion system, which is connected to the USV autopilot. The USB flash drive is connected to the USV autopilot, the ground station QGC is wirelessly connected to the USV autopilot, the data transmission module interface is wirelessly connected to the USV autopilot, and the shore-based controller is connected to the data transmission module interface.

[0038] Furthermore, the internal process of implementing flow control and event response mechanisms within the system is as follows:

[0039] (1) The RTK data reading subtask detects and parses NMEA messages in a loop after initializing the serial port, and injects the updated latitude, longitude and time information into the circular buffer for the data fusion module to call at any time;

[0040] (2) Water depth data parsing subtask, then real-time decoding of SDBTT messages, writing instantaneous water depth values ​​into a circular buffer, and waiting for fusion processing together with positioning data;

[0041] (3) The data fusion and transmission subtask periodically retrieves data from the circular buffer. Once a water depth value and location data that can be associated are found, the fusion and data packaging process is triggered, and the packaged data frame is sent to the unmanned vessel and LORA wireless link to achieve external output.

[0042] The specific process for system parameter adjustment and status change is as follows:

[0043] (1) When the sampling start command is received, the system starts the continuous data recording and transmission process;

[0044] (2) After receiving instructions such as stop sampling or change transmission frequency, the system adjusts the running status and data writing strategy of the corresponding subtasks according to the instructions.

[0045] The present invention, by adopting the above-described technical solution, has the following beneficial effects:

[0046] This invention integrates an autopilot module, a GPS positioning unit, and a depth sensor to achieve real-time fusion of water depth data with current location and heading information. Simultaneously, it employs wireless communication methods such as LoRa to synchronously transmit the fused data to a shore-based controller for local display and redundant storage. Even in the event of power outages or equipment malfunctions, the recorded data remains intact on the shore-based controller, improving data storage reliability. Furthermore, by using the drone as a temporary server and employing high-frequency acoustic communication, it can better overcome the influence of complex environments. Attached Figure Description

[0047] Figure 1 This is a system block diagram of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are merely to provide the reader with a thorough understanding of one or more aspects of the present invention, and these aspects of the invention can be implemented even without these specific details.

[0049] A method for acquiring and transmitting water depth data from an unmanned surface vessel (USV) with location association and redundant storage capabilities, comprising the following steps:

[0050] Step 1: Multi-source data acquisition

[0051] Depth data (such as SDBTT messages) from the depth sounder is acquired via serial port 1. Positioning information (such as GGA and RMC messages) from the RTK positioning device is acquired via serial port 2. The unmanned surface vessel's autopilot is connected via serial port 3 to enable the transmission of fused data and the reception of commands.

[0052] 1.1 Depth Sounder Data Reading

[0053] Listen to the NMEA0183 format message (SDDBT, water depth value 1, water depth value 2, water depth value 3, F* checksum) output by the depth sounder through serial port 1.

[0054] Each received message is placed in a circular buffer for depth sounding data for subsequent parsing.

[0055] 1.2 RTK Positioning Data Reading

[0056] Listen to the NMEA 0183 messages (such as GGA, RMC, etc.) output by the RTK positioning device via serial port 2.

[0057] Each received message is placed into a location data circular buffer for subsequent parsing.

[0058] 1.3 Autopilot Serial Port Interface

[0059] Communicate with the unmanned surface vessel's autopilot via serial port 3: Receive control commands or requests from the autopilot (such as start sampling, stop sampling, change transmission frequency, etc.). Package the fused depth and positioning data and transmit it to the autopilot.

[0060] Step 2: Data parsing and preprocessing

[0061] Parse the bathymetry and positioning messages to extract key fields (such as timestamp, latitude, longitude, and depth). Convert the extracted latitude and longitude information from degrees to decimals (if necessary). Filter out abnormal or invalid data and perform interpolation repair if necessary.

[0062] 2.1 Message Field Splitting

[0063] Use commas as delimiters or other suitable methods (regular expressions, etc.) to split NMEA messages into independent fields. For GGA messages, extract fields such as time, latitude, longitude, positioning quality, number of satellites, and altitude. For RMC messages, extract fields such as time, positioning status, latitude, longitude, speed, heading, and date. For SDBPT messages, extract water depth values ​​and their units.

[0064] 2.2 Unit and Format Conversion

[0065] Convert latitude and longitude in degrees to decimal format. Also, convert water depth values ​​to meters (m).

[0066] 2.3 Handling outliers and missing values.

[0067] Anomalies are identified when the water depth value is negative, and if anomalies are found, they are marked or filtered out. Missing water depth values ​​can be interpolated or discarded as appropriate.

[0068] Step 3: Time Synchronization and Data Fusion

[0069] Synchronization and matching of multi-source data are performed based on timestamps. Depth and positioning data with similar times (within a set threshold) are bound together to obtain a fused data structure containing both location and depth. Data exceeding the time synchronization threshold can be processed by waiting, discarding, or interpolation.

[0070] 3.1 Time Synchronization

[0071] Establish a unified time reference (based on the timestamps provided by RTK). Compare the timestamps of the water depth data and the positioning data. If the time difference between the two is within the threshold of ±0.1 seconds, they are considered to correspond to the same time period and can be directly fused.

[0072] If the threshold is exceeded, it will be handled as follows:

[0073] Interpolation strategy: When the interval between the two is too large, use the aligned data to perform linear interpolation and estimate the mean of the water depth or position at the intermediate time.

[0074] 3.2 Data Fusion

[0075] By binding time-aligned water depth values ​​with latitude, longitude, altitude, and heading, a new fused data structure is formed, which includes timestamp, latitude, longitude, water depth, heading, and speed.

[0076] Step 4: Data Packaging and Transmission

[0077] The fused data is packaged according to the set protocol format, including frame headers, frame sequence numbers, checksums, etc. It is then transmitted to the unmanned surface vessel's autopilot via serial port 3, and from there transmitted via the autopilot's wireless link to the ground station and shore-based controller. The fused data is stored and displayed at the ground station and shore-based controller for real-time monitoring.

[0078] 4.1 Data Frame Structure Design

[0079] After fusion, data frames are assembled according to a custom protocol: Frame header (fixed byte: 0xAA55), used to identify the start of data; Data content (timestamp, latitude, longitude, water depth, heading, speed, etc.), fixed bytes; Frame sequence number, to facilitate the receiver's detection of packet loss or out-of-order delivery; Checksum field (F*checksum), to ensure that the data has not been tampered with or corrupted.

[0080] 4.2 Serial Port Parameters and Transmission Strategy

[0081] Select a baud rate (e.g., 115200bps) that matches the unmanned surface vessel's autopilot. To ensure real-time performance and stability, a batch packetization method is adopted, where every N data points are packaged into a single data block and sent together to reduce transmission overhead.

[0082] 4.3 Receiver Processing

[0083] After receiving data, the autopilot forwards it to the ground station and shore-based controller via a built-in or external wireless communication module. The ground station and shore-based controller display the ship's position, course, and depth curve in real time, and store the data locally.

[0084] Step 5: Redundant Storage and Fault Response

[0085] On the unmanned surface vessel (USV), real-time or periodically packaged data is stored locally using storage media such as USB flash drives. Data received at the shore-based control station is also redundantly stored to prevent data loss due to link interruptions or equipment failures. When the network is restored or the USV returns to shore, the data on the USB flash drive can be compared, merged, or updated with the shore-based data.

[0086] 5.1 USB flash drive local storage

[0087] After data generation or processing is complete, the unmanned vessel periodically writes the data to a USB flash drive: Segmented storage: Every 10 minutes or when the data volume reaches a threshold, a new file is created to prevent a single file from becoming too large. Verification and breakpoint continuation: The file is verified after writing is complete; if power is lost during the process, it can be checked and resumed upon the next power-on.

[0088] 5.2 Shore-based redundant storage

[0089] After receiving data, the shore-based controller synchronously writes it to a USB flash drive, creating another backup. This forms a primary and backup storage system with the QGC ground station, preventing data loss or errors due to the failure of a single device.

[0090] like Figure 1 As shown, the system for acquiring and transmitting water depth data from an unmanned surface vessel (USV) with location association and redundant storage functions includes an RTK positioning system, a depth sounding sensor, a data fusion system, an USV autopilot, a USB flash drive, a ground station QGC, a data transmission module interface, and a shore-based controller. The RTK positioning system and the depth sounding sensor are both connected to the data fusion system, which is connected to the USV autopilot. The USB flash drive is also connected to the USV autopilot. The ground station QGC is wirelessly connected to the USV autopilot, the data transmission module interface is wirelessly connected to the USV autopilot, and the shore-based controller is connected to the data transmission module interface.

[0091] The unmanned surface vessel (USV) is equipped with a high-frequency acoustic transmitter. When the USV loses communication with the ground station and shore-based controller, the USV's high-frequency acoustic transmitter activates to seek communication. The ground station is equipped with a relay drone, which carries a high-frequency acoustic receiver. When the ground station and shore-based controller lose communication with the USV, the relay drone is launched and flies to the latitude and longitude of the USV last received by the ground station. It then establishes high-frequency acoustic communication with the USV until communication between the USV and the ground station and shore-based controller is restored, or until personnel determine the USV's exact location and manually control the relay drone to fly back. This effectively avoids the problems of the USV losing contact and being difficult to locate.

[0092] If communication cannot be established even after launching the drone, it is determined that the machinery has malfunctioned and cannot function.

[0093] The system achieves synchronous acquisition and parsing of multi-source data through three independent serial port channels:

[0094] (1) Serial port 1 is used to communicate with the water depth measuring instrument, and to digitally collect and parse the output SDBTT messages to obtain real-time water depth data (water depth value change per unit time).

[0095] (2) Serial port 2 is used to communicate with RTK positioning equipment, digitally collect and parse NMEA standard format messages such as RMC and GGA, obtain real-time latitude, longitude and elevation information, and give spatial position and time reference to water depth data.

[0096] (3) Serial port 3 is directly connected to the serial port interface of the unmanned vessel control terminal to transmit the processed water depth data associated with geographic coordinates to the unmanned vessel, realizing local data integration and status sharing. This serial port also receives control commands or communication feedback information from the unmanned vessel.

[0097] During the data acquisition and parsing process, the system introduces a multi-layered logical parsing and data fusion mechanism as follows:

[0098] (1) Real-time fusion of water depth data and RTK positioning data, binding water depth values ​​with geographic location parameters at the same timestamp, so that the operator can intuitively interpret underwater terrain changes in a graphical way during later data analysis or real-time monitoring.

[0099] (2) The data fusion unit synchronizes and calibrates the data of serial port 1 and serial port 2 in the logic controller, and integrates the water depth data and latitude and longitude information into a target data frame with geographic reference coordinates according to the set rules.

[0100] The process of remote data transmission and monitoring using a LoRa module in a wireless communication link is as follows:

[0101] (1) After the fusion is completed, the system sends the water depth and positioning data to the shore-based controller through the LORA link. After receiving the signal, the shore-based controller can display and monitor the ship's position, water depth parameters and communication status in real time in the graphical interface.

[0102] (2) LORA communication has the advantages of low power consumption, anti-interference and long-distance transmission. Even in relatively complex aquatic environments, it can maintain the stability and continuity of the data link.

[0103] The redundant data storage mechanism ensures data security and traceability through the following process:

[0104] (1) The system is configured with a USB interface to connect to a USB flash drive storage medium and write the fusion data acquired in real time or periodically to the USB flash drive.

[0105] (2) In the event of network interruption, equipment malfunction (such as power failure or system crash), or unstable transmission, even if the shore-based system cannot obtain all the data in a timely manner, the records on the USB drive can still ensure the complete preservation of the survey data. Operators can subsequently export the data from the USB drive for later manual analysis, correction, or tracing of underwater survey results.

[0106] To ensure the orderly execution of data processing logic, the system internally implements process control and event response mechanisms as follows:

[0107] (1) The RTK data reading subtask initializes the serial port and then continuously detects and parses the NMEA messages, injecting the updated latitude, longitude and time information into the circular buffer for the data fusion module to call at any time.

[0108] (2) The water depth data parsing subtask decodes the SDBDT message in real time in a similar manner, writes the instantaneous water depth value into the circular buffer, and waits for fusion processing together with the positioning data.

[0109] (3) The data fusion and transmission subtask periodically retrieves data from the ring buffer. Once a water depth value and location data that can be associated are found, the fusion and data packaging process is triggered, and the packaged data frame is sent to the unmanned vessel and LORA wireless link to achieve external output.

[0110] When receiving instructions from a shore-based controller or unmanned surface vessel, the system can flexibly adjust parameters and change states as follows:

[0111] (1) When the sampling start command is received, the system starts the continuous data recording and transmission process.

[0112] (2) After receiving instructions such as stop sampling or change transmission frequency, the system adjusts the running status and data writing strategy of the corresponding subtasks according to the instructions.

[0113] Matters not covered in this invention are common knowledge.

[0114] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for acquiring and transmitting water depth data from an unmanned surface vessel (USV) with location association and redundant storage functions, characterized in that: The method includes the following steps: Step 1: Data acquisition. The depth data from the depth sounder and the positioning information from the RTK positioning device are acquired through the serial port. The acquired data are fused and then transmitted to the unmanned vessel's autopilot to realize the transmission of fused data and the reception of commands. Step 2: Data parsing and preprocessing, format parsing of depth sounding and positioning messages, extraction of key fields, conversion of extracted latitude and longitude information from degree-minute format, filtering of abnormal or invalid data, and interpolation repair as needed; Step 3: Time synchronization and data fusion. Data synchronization and matching are performed based on timestamps. Etching and positioning data with similar times are bound together to obtain a fused data structure containing location and depth. Data exceeding the time synchronization threshold is processed by waiting, discarding, or interpolation. Step 4: Data Packaging and Transmission. The fused data is packaged according to the set protocol format, with frame headers, frame sequence numbers, and checksums added. It is then sent to the unmanned vessel's autopilot via a serial port, and then transmitted to the ground station and shore-based controller via the autopilot's wireless link. The fused data is stored and displayed at the ground station and shore-based controller to achieve real-time monitoring. Step 5: Redundant storage and fault response. Real-time or periodic data is packaged and stored locally on the unmanned vessel using storage media. Data received at the shore-based control terminal is also redundantly stored to prevent data loss due to link interruption or equipment failure. When the network is restored or the unmanned vessel returns to shore, the data on the storage media is checked, merged, or updated with the shore-based data.

2. The method for acquiring and transmitting unmanned surface vessel depth data with location association and redundant storage functions according to claim 1, characterized in that: The specific process of step 1 is as follows: Step 1.1: Read depth sounder data. Listen to the NMEA 0183 format messages output by the depth sounder through the first serial port 1. The messages include three water depth values ​​and check data. Each message received is placed into the depth sounding data circular buffer for subsequent parsing. Step 1.2: RTK positioning data reading. Listen for NMEA 0183 messages output by the RTK positioning device through serial port 2. Each received message is placed into the positioning data circular buffer for subsequent parsing. Step 1.3: Serial port interface of the autopilot. Communicate with the autopilot of the unmanned vessel through serial port 3, receive control commands sent by the autopilot, including start sampling, stop sampling and change transmission frequency, and package the fused water depth data and positioning data and transmit them to the autopilot.

3. The method for acquiring and transmitting unmanned surface vessel depth data with location association and redundant storage functions according to claim 1, characterized in that: The specific process of step 2 is as follows: Step 2.1: Split the message fields. Using commas as delimiters or regular expressions, split the NMEA message into independent fields. For GGA messages, extract the fields of time, latitude, longitude, positioning quality, number of satellites, and altitude. For RMC messages, extract the fields of time, positioning status, latitude, longitude, speed, heading, and date. For SDBTT messages, extract the water depth value and its depth unit. Step 2.2: Unit and format conversion. Convert latitude and longitude in degree and minute format to decimal format in degrees, and convert the water depth value unit to meters. Step 2.3: Handling outliers and missing values. Anomaly detection is performed for cases such as negative water depth values. If outliers are found, they are marked or filtered. Missing water depth values ​​are interpolated before or after the specified values ​​or discarded.

4. The method for acquiring and transmitting unmanned surface vessel depth data with location association and redundant storage functions according to claim 1, characterized in that: The specific process of step 3 is as follows: Step 3.1: Time synchronization. Establish a unified time reference. Based on the timestamp provided by RTK, compare the timestamps of the water depth data and the positioning data. If the time difference between the two is within ±0.1 seconds, they are considered to correspond to the same time period and can be directly fused. If the difference exceeds the threshold, it is handled as follows: Interpolation strategy: When the interval between the two is greater than the set value, use the aligned data before and after to perform linear interpolation and estimate the mean of the water depth or position at the intermediate time. Step 3.2: Data fusion. Bind the time-aligned water depth values ​​with latitude, longitude, altitude and heading to form a new fused data structure, namely timestamp, latitude, longitude, water depth, heading and speed.

5. The method for acquiring and transmitting unmanned surface vessel depth data with location association and redundant storage functions according to claim 1, characterized in that: The specific process of step 4 is as follows: Step 4.1: Data frame structure design. After fusion, assemble the data frame, data content, fixed characters, frame sequence number and check field according to the custom protocol. The frame header is a fixed byte 0xAA55, which is used to identify the start of data. The data content includes timestamp, latitude, longitude, water depth, heading and speed. The fixed bytes and frame sequence number facilitate the receiver to detect packet loss or out-of-order delivery. The check field is an F* checksum to ensure that the data has not been tampered with or damaged. Step 4.2: Serial port parameters and transmission strategy. Select a baud rate that matches the unmanned vessel's autopilot. To ensure real-time performance and stability, use a batch packaging method to package every N data items into a data block and send them together to reduce transmission overhead. Step 4.3: Receiver processing. After receiving the data, the autopilot forwards the data to the ground station and shore-based controller via the built-in or external wireless communication module. The ground station and shore-based controller display the ship's position, heading, and water depth curve in real time, and store the data locally.

6. The method for acquiring and transmitting unmanned surface vessel depth data with location association and redundant storage functions according to claim 1, characterized in that: The specific process of step 5 is as follows: Step 5.1: Local storage on USB flash drive. After the data is generated or processed, the unmanned vessel periodically writes the data to the USB flash drive for segmented storage. Every 10 minutes or when the data volume reaches a threshold, a new file is created to prevent a single file from exceeding the set value. Verification and breakpoint continuation are performed. After the writing is completed, the file is verified. If the power is lost in the middle, it will be detected and resumed after the next power-on. Step 5.2: Shore-based redundant storage. After receiving data, the shore-based controller synchronously writes it to a USB flash drive to form another backup. This creates a primary and backup storage method with the QGC ground station to prevent data loss or errors due to the failure of a single device.

7. The method for acquiring and transmitting unmanned surface vessel depth data with location association and redundant storage functions according to claim 1, characterized in that: In step 5, the unmanned surface vessel (USV) is equipped with a high-frequency acoustic transmitter. When the USV loses communication with the ground station and shore-based controller, the USV's high-frequency acoustic transmitter activates to seek communication. The ground station is equipped with a relay drone, which carries a high-frequency acoustic receiver. When the ground station and shore-based controller lose communication with the USV, the relay drone is launched and flies to the latitude and longitude of the USV last received by the ground station. It then establishes high-frequency acoustic communication with the USV until communication between the USV and the ground station and shore-based controller is restored, or until staff determine the USV's exact location and manually control the relay drone to fly back. This effectively avoids the problems of the USV losing contact and being difficult to locate.

8. The system for unmanned surface vessel (USV) depth data acquisition and transmission method with location association and redundant storage functions according to any one of claims 1-7, characterized in that: It includes an RTK positioning system, a depth sounding sensor, a data fusion system, an unmanned surface vessel (USV) autopilot, a USB flash drive, a ground station QGC, a data transmission module interface, and a shore-based controller. The RTK positioning system and the depth sounding sensor are both connected to the data fusion system, which is connected to the USV autopilot. The USB flash drive is connected to the USV autopilot, the ground station QGC is wirelessly connected to the USV autopilot, the data transmission module interface is wirelessly connected to the USV autopilot, and the shore-based controller is connected to the data transmission module interface.

9. The system for unmanned surface vessel depth data acquisition and transmission method with location association and redundant storage function according to claim 8, characterized in that: The internal process of implementing flow control and event response mechanisms within the system is as follows: (1) The RTK data reading subtask detects and parses NMEA messages in a loop after initializing the serial port, and injects the updated latitude, longitude and time information into the circular buffer for the data fusion module to call at any time; (2) Water depth data parsing subtask, then real-time decoding of SDBTT messages, writing instantaneous water depth values ​​into a circular buffer, and waiting for fusion processing together with positioning data; (3) The data fusion and transmission subtask periodically retrieves data from the ring buffer. Once a water depth value and location data that can be associated are found, the fusion and data packaging process is triggered, and the packaged data frame is sent to the unmanned vessel and LORA wireless link to achieve external output.

10. The system for unmanned surface vessel depth data acquisition and transmission method with location association and redundant storage function according to claim 8, characterized in that: The specific process for system parameter adjustment and status change is as follows: (1) When the sampling start command is received, the system starts the continuous data recording and transmission process; (2) After receiving instructions such as stop sampling or change transmission frequency, the system adjusts the running status and data writing strategy of the corresponding subtasks according to the instructions.

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