A corner monitoring system during untwisting release of a submarine cable

Abstract

The application discloses a kind of corner monitoring systems when submarine cable untwisting is released, belong to the technical field of ocean engineering monitoring;The corner monitoring system is integrated double backup inertial navigation module, low temperature battery module, pressure-resistant shell module and CAN communication storage shell module, realize the high-precision monitoring and reliable operation of submarine cable untwisting process;Among them, double backup inertial navigation module adopts Kalman filtering data fusion algorithm, combined with redundancy switching mechanism, the accuracy of corner measurement is improved by more than 30% than traditional single inertial navigation system;Low temperature battery module is through special electrode material and electrolyte formula, cooperate with tri-electrode ear structure, can be stabilized in-35 DEG C~45 DEG C environment Power supply;CAN communication storage shell module is based on CAN2.0B protocol to realize anti-interference data transmission, error rate is less than 10 ‑8 , and through NAND flash to realize data check backup and 6 months continuous storage;The application can provide accurate data support for submarine cable laying, guarantee submarine cable laying quality and long-term safe operation.

Description

Technical Field

[0001] This invention belongs to the field of marine engineering monitoring technology, specifically a system for monitoring the angle of a submarine cable during unwinding and release. Background Technology

[0002] Deep-sea umbilical cable stress relief devices are primarily used to eliminate mechanical stress generated during the manufacturing, transportation, and storage of umbilical cables, ensuring the safety of deployment of heavy-duty deep-sea equipment and the long-term stability of power transmission and signal control. Currently, the mainstream stress relief methods in the industry include: Vertical static placement: The umbilical cable is suspended vertically to release stress naturally, suitable for short-distance cables. Horizontal rolling deployment: The cable is rolled using rollers, relying on friction to relieve stress, but is susceptible to roller jamming. Manual large-circle static placement: The cable is manually coiled into a large-diameter ring and placed statically, limited by working space. Some patents use multi-segment roller-type elastic buffer mechanisms to achieve continuous stress relief, but the structure is complex, reliability is low, and it is prone to failure due to roller jamming under alternating ship loads; furthermore, open bearings are difficult to resist salt spray corrosion. Other patents use relative rotation between the winding drum and connecting drum to prevent cable tangling, but this is only suitable for small-section cables.

[0003] Existing technologies have significant drawbacks: 1. Poor adaptability: Designed for short-distance, small-section, and low-linear-density cables, they cannot meet the stress release requirements of "long-distance, large-section, and high-linear-density" umbilical cables in heavy-duty deep-sea scenarios. 2. Weak environmental adaptability: The open structure is susceptible to corrosion from high salt spray, leading to wear and failure; under six-degree-of-freedom alternating loads on a ship, the device's attitude is unstable, resulting in low stress release efficiency. 3. High operational difficulty: Manual coiling requires a large deck space, while ship decks are narrow and swaying, significantly increasing operational risks. 4. Limited functionality: Only stress release can be achieved; it cannot simultaneously complete the functional verification of deep-sea environmental monitoring and deployment / recovery systems.

[0004] Therefore, developing a deep-sea umbilical cable stress relief device that combines load adjustability, corrosion resistance reliability, attitude adaptability, and functional integration is of key significance for improving the operational safety of deep-sea equipment and extending the service life of umbilical cables. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned defects of existing submarine cable turning angle monitoring systems and provide a turning angle monitoring system for submarine cable unwinding and release, specifically achieving the following objectives: (1) Improve the accuracy of turning angle monitoring: Through redundant inertial navigation and data fusion technology, the measurement error is controlled within ±0.1°, which is more than 30% higher than the traditional solution. (2) Adapt to harsh marine environments: Achieve stable power supply at low temperatures of -40℃ to 50℃, high-pressure protection at water depths of 0 to 1000 meters, and MTBF ≥ 500 hours in salt spray environment. (3) Ensure reliable data transmission and storage: Adopt an anti-interference communication bus to achieve a bit error rate < 10-8 Data transmission; ensure no data loss through local large-capacity storage and verification backup. (4) Achieve automatic fault switching: automatically switch to backup unit when the inertial navigation module fails, without stopping the machine, ensuring the continuity of laying operations.

[0006] To achieve the above objectives, the specific technical solution is as follows:

[0007] A submarine cable de-torsion release angle monitoring system includes a pressure-resistant housing, wherein a dual backup inertial navigation module, a cryogenic battery module and a CAN communication storage housing module are installed inside the pressure-resistant housing.

[0008] The dual-backup inertial navigation module includes a first inertial navigation unit and a second inertial navigation unit. The first inertial navigation unit and the second inertial navigation unit integrate a high-precision MEMS gyroscope, a three-axis accelerometer, a three-axis magnetometer, and a data processing chip. The first inertial navigation unit and the second inertial navigation unit are connected through a fusion processing unit. The fusion processing unit uses an unscented Kalman filter algorithm to fuse the preprocessed data of the first inertial navigation unit and the second inertial navigation unit. When any inertial navigation unit fails, the other inertial navigation unit can seamlessly switch to work within <10ms.

[0009] The low-temperature battery module includes a cell assembly, tabs, and a smart management BMS system. The cell assembly uses lithium nickel cobalt manganese oxide doped with graphene as the positive / negative electrode material, and the electrolyte is a mixed solution of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, with added fluoroethylene carbonate. The tabs are made of nickel-plated copper and are uniformly distributed on the cell current collector. The smart management BMS system integrates a voltage sensor, a current sensor, a temperature sensor, and a heating element, which can monitor the battery status in real time and automatically adjust the charging and discharging strategy.

[0010] The pressure-resistant shell is made of TC4 titanium alloy with a wall thickness of 15mm. It has an internal nitrile rubber buffer layer and is equipped with four double O-ring sealing interfaces, which can withstand 10MPa water pressure.

[0011] The CAN communication storage housing module integrates a CAN communication controller, a CAN transceiver, a data storage unit, and a CRC check unit; the CAN communication controller supports the CAN2.0B protocol with a communication rate of 500kbps; the data storage unit uses 8GB NAND flash memory and supports dual-zone backup and CRC check unit verification.

[0012] In a preferred embodiment of the present invention, the data processing chip adopts an STM32H743IIT6 MCU, which performs moving average filtering and Kalman filtering preprocessing on the raw data of the gyroscope and accelerometer in sequence, and calibrates the magnetometer data using an elliptic fitting algorithm, with a filtering window size of 10 data points; the fusion processing unit is implemented based on an EP4CE10F17C8N FPGA, and dynamically allocates the data weights of the two units through historical error variance.

[0013] In a preferred embodiment of the present invention, the battery pack consists of four cells connected in series, with a total voltage of 14.8V and a capacity of 20Ah; in an environment of -40℃, the discharge rate is ≥0.5C and the continuous discharge time is ≥20 hours; the intelligent management BMS system is built based on an STM32L431RCT6 MCU, and sends an early warning signal when the state of charge (SOC) is <20% or the cell temperature is <-35℃ or >45℃.

[0014] In a preferred embodiment of the present invention, the outer surface of the pressure-resistant shell is treated with a micro-arc oxidation coating with a coating thickness of 10 μm, and no rust is observed after 5000 hours of salt spray testing; the internal nitrile rubber buffer layer can attenuate the external vibration acceleration from 10g to less than 1g.

[0015] In a preferred embodiment of the present invention, the CAN transceiver (412) is a TJA1050 type, the CAN bus uses shielded twisted-pair cable for transmission, and 120Ω terminating resistors are connected in parallel at both ends, resulting in a data transmission error rate of <10. -8 The 8GB NAND flash memory uses the K9F1208U0C model, with a data retention time of ≥10 years, and supports querying and backtracking by time range.

[0016] In a preferred embodiment of the present invention, the gyroscope of the dual backup inertial navigation module is an ADIS16488 type with zero bias stability ≤0.1° / h; the accelerometer is an LSM6DSO type with a resolution of 0.000244g; and the magnetometer is a BMM150 type with a resolution of 0.3μT.

[0017] In a preferred embodiment of the present invention, the angle monitoring system is fixed to the submarine cable 1 meter downstream of the submarine cable untwisting device by a specially made stainless steel 316L clamp. The inner diameter of the clamp matches the outer diameter of the submarine cable, and it is tightened with a torque wrench at a torque of 30 N·m to ensure that the system moves synchronously with the submarine cable.

[0018] Compared with the prior art, the embodiments of the present invention provide a rotation angle monitoring system during submarine cable unwinding and release. Through the coordinated design of four core modules, it has the following significant advantages:

[0019] (1) Significantly improved corner monitoring accuracy: The dual backup inertial navigation module solves the zero drift error and fault interruption problems of traditional single inertial navigation through "redundant hardware + data fusion algorithm".

[0020] Accuracy Improvement: Laboratory tests (using a high-precision turntable to simulate submarine cable untwisting, with a turntable accuracy of ±0.001°) show that the rotation angle measurement error of this system is ±0.1°, which is more than 30% higher than that of a traditional single inertial navigation system (error ±0.3°) and more than 86% higher than that of a mechanical encoder (error ±1.5°).

[0021] Improved stability: With magnetometer-assisted calibration and hourly zero-bias calibration, the cumulative angle error of the system during long-term operation (24 hours) is <0.5°, which is far lower than the 2°~3° cumulative error of traditional systems. It can accurately reflect the subtle angle changes during the cable untwisting process and provide real-time adjustment basis for laying operators (such as reducing the untwisting speed in time when the angle rate exceeds the preset threshold to avoid stress concentration).

[0022] (2) Strong adaptability to harsh marine environments:

[0023] Low temperature adaptability: The low temperature battery module can achieve a discharge rate of 0.5C at -35℃, meeting the system's peak power consumption requirement of 10W and a continuous discharge time of ≥20 hours; while traditional lithium-ion batteries can hardly discharge at -40℃. This system can be adapted to the laying operations in high-latitude cold sea areas (such as offshore wind farms around Northern Europe and the Arctic).

[0024] High pressure protection: The pressure-resistant shell is made of TC4 titanium alloy and double O-ring seals, which can withstand 10MPa water pressure (1000 meters water depth). After deep-sea simulation test (10MPa pressure holding in a high pressure vessel for 24 hours), the internal electronic components showed no water leakage and no functional abnormalities, making it suitable for deep-sea cable laying.

[0025] Corrosion protection and vibration reduction: The micro-arc oxidation coating and nitrile rubber buffer layer enable the system to have an MTBF of ≥500 hours in a salt spray environment (compared to <100 hours for traditional systems) and a vibration acceleration attenuation rate of >90%, ensuring long-term stable operation of the system in the marine environment of rough seas and salt spray corrosion.

[0026] (3) High reliability of data transmission and storage:

[0027] Interference-resistant transmission: The differential transmission and shielding design of the CAN bus ensures a data transmission error rate of <10. -8 Far lower than the 10 of RS485 bus -5 Even in environments with strong electromagnetic interference during the laying of the ship, it can ensure the real-time transmission of turning angle data and equipment status data without loss or error.

[0028] Secure storage: The large-capacity storage and dual-zone backup strategy of NAND flash memory can achieve 2 months of continuous data storage and data retention time of ≥10 years; even if the shipboard communication is interrupted (such as satellite signal loss), the locally stored data can be retrieved after the communication is restored, providing complete data support for subsequent submarine cable laying process optimization (such as analyzing the relationship between untorsion rate and stress distribution) and submarine cable health assessment (such as judging whether there is torsional damage in the submarine cable by the change of angle).

[0029] (4) The corner monitoring system is easy to operate and maintain, and has high operational continuity:

[0030] Automatic fault switching: The fault switching time of the dual backup inertial navigation modules is <10ms, requiring no manual intervention, avoiding downtime in laying operations due to inertial navigation failures (traditional systems require downtime of 1-2 hours to replace modules), and improving work efficiency;

[0031] Intelligent early warning: The BMS of the low-temperature battery module can monitor the power and temperature in real time and issue early warnings of low power and over-temperature. Staff can replace the battery before the system shuts down to avoid sudden power outages.

[0032] Convenient maintenance: The sealed interface design of the pressure-resistant shell facilitates cable connection and battery charging, extending the maintenance cycle (once a month) by 50% compared to the traditional system (once every two weeks); calibration can be performed remotely by sending "calibration commands" via the ship's CAN bus, eliminating the need for frequent system disassembly and reducing maintenance costs. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This application provides a schematic diagram of the overall structure of a submarine cable unwinding and release angle monitoring system according to an embodiment of the present application.

[0035] Figure 2 This application provides a schematic diagram of the internal structure of a dual-backup inertial navigation module.

[0036] Figure 3 This is a schematic diagram of the structure of a low-temperature battery module provided in an embodiment of this application.

[0037] Figure 4 This application provides a schematic diagram of the data transmission and storage process of a CAN communication storage shell module. Detailed Implementation

[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The terms "upper," "lower," "front," "rear," "left," and "right," etc., used when describing the installation position or direction of the structure or components in this embodiment are based on the orientation shown in the accompanying drawings. They are merely for convenience of description, used to distinguish the relative positions of various components or directions, and do not represent the orientation of the system or functional components in this embodiment during use.

[0039] like Figures 1-4 As shown, this embodiment of the invention provides a submarine cable untwisting and release angle monitoring system, including a pressure-resistant housing 3. The pressure-resistant housing 3 houses a dual-backup inertial navigation module 1, a cryogenic battery module 2, and a CAN communication storage housing module 4. These modules work collaboratively to achieve high-precision monitoring and reliable operation of the submarine cable's angle. This angle monitoring system can accurately monitor angle changes during the submarine cable untwisting process, adapt to harsh marine environments such as low temperatures and high pressures, and achieve reliable data storage and transmission. It provides accurate data support for submarine cable laying, ensuring the smooth progress of cable laying and the safe operation of the submarine cable. In this embodiment, the pressure-resistant housing 3 has a port 41 on its surface for the communication storage housing module 4, used for cable entry / exit from the pressure-resistant housing.

[0040] The dual-backup inertial navigation module 1 is the core of the angle measurement, used to acquire the angular rate, linear acceleration, and azimuth information of the submarine cable in real time. Through redundant design and data fusion algorithm, the measurement accuracy and continuity are ensured. The dual-backup inertial navigation module 1 includes a first inertial navigation unit 11 and a second inertial navigation unit 12. The first inertial navigation unit 11 and the second inertial navigation unit 12 integrate a high-precision MEMS gyroscope 111, a three-axis accelerometer 112, a three-axis magnetometer 113, and a data processing chip 114. The first inertial navigation unit 11 and the second inertial navigation unit 12 are connected through a fusion processing unit 13. The fusion processing unit 13 uses an unscented Kalman filter algorithm to fuse the preprocessed data of the first inertial navigation unit 11 and the second inertial navigation unit 12. When either inertial navigation unit fails, the other inertial navigation unit can seamlessly switch to work within <10ms. In this embodiment, the fusion processing unit 13 determines the inertial navigation unit fault by the following indicators: no data output for 50 ms continuously, or the deviation of the rotation angle data between the two units is >0.5° and lasts for 50 ms; after the fault occurs, a fault warning is sent through the CAN bus, which includes the fault unit number and the fault type.

[0041] The dual-backup inertial navigation module 1 uses an ADIS16488 gyroscope with a zero-bias stability of ≤0.1° / h; an LSM6DSO accelerometer with a resolution of 0.000244g; and a BMM150 magnetometer with a resolution of 0.3μT. Specifically, the high-precision MEMS gyroscope 111 is an ADIS16488 MEMS gyroscope from Analog Devices, with an angular rate measurement range of ±450° / s and a zero-bias stability of ≤0.1° / h, capable of real-time acquisition of the submarine cable's rotational angular rate around its axis. The triaxial accelerometer 112 is an STMicroelectronics LSM6DSO triaxial accelerometer with a measurement range of ±16g and a resolution of 0.000244g, used to acquire the linear vibration acceleration of the submarine cable and assist in eliminating vibration interference. The triaxial magnetometer 113 uses a Bosch BMM150 model, with a measurement range of ±1300μT and a resolution of 0.3μT. By acquiring geomagnetic information, it assists in calibrating the azimuth drift of the gyroscope, improving long-term measurement stability. The data processing chip 114 uses an STM32H743IIT6 MCU with a main frequency of 480MHz and a hardware floating-point unit (FPU), which can perform preprocessing such as filtering and calibration on the raw data in real time.

[0042] Data preprocessing workflow:

[0043] Filtering: The data processing chip uses a combination algorithm of moving average filtering and Kalman filtering. First, the moving average filtering (window size 10) removes high-frequency noise (such as instantaneous vibrations caused by wave impact). Then, the Kalman filtering (state vector includes angular rate, acceleration, and magnetometer readings) further reduces random errors.

[0044] Zero bias calibration: The system automatically performs zero bias calibration of the gyroscope once per hour. The system pauses the acquisition of submarine cable motion data and detects the "stationary state" (accelerometer magnitude close to 9.81m / s²) by accelerometer. At this time, the gyroscope output value is recorded as the zero bias. The zero bias value is subtracted in real time during subsequent measurements to eliminate long-term zero drift error.

[0045] Magnetometer calibration: The magnetometer is calibrated using an ellipse fitting algorithm to detect hard iron interference (such as the magnetic field generated by the pressure-resistant metal casing) and soft iron interference (such as the magnetic field of the cable) to ensure the accuracy of geomagnetic orientation measurement.

[0046] Data fusion and redundancy switching mechanism:

[0047] Data fusion: The preprocessed data of the two inertial navigation units is transmitted to the fusion processing unit (implemented based on the FPGA chip EP4CE10F17C8N). The fusion is performed using the unscented Kalman filter (UKF) algorithm. UKF can handle nonlinear systems (such as the coupling relationship between inertial navigation data and geomagnetic data). By calculating the error variance of the two unit data (based on historical measurement accuracy statistics), the weights are dynamically allocated (the unit with the smaller error accounts for 60%~80% of the weight). Finally, the fused rotation angle value is output (rotation angle = ∫ angular rate dt, integration time step 1ms).

[0048] Fault switching: The fusion processing unit monitors the working status of the two inertial navigation units in real time and judges faults through the following indicators.

[0049] Data continuity: If a unit has no data output for 50ms, it is judged as a "communication failure";

[0050] Data rationality: If the angular rate value of a certain unit exceeds the normal range (>100° / s, the maximum angular rate of submarine cable untwisting is usually <50° / s), or the acceleration modulus value deviates from 9.81m / s² by more than 1m / s², it is judged as "measurement failure".

[0051] Switching logic: When any unit is found to be faulty, the fusion processing unit immediately stops the data input of that unit and only uses the data of the normal unit for calculation. The switching time is <10ms to ensure uninterrupted monitoring. At the same time, an "Inertial Navigation Unit Fault" warning signal is sent to the monitoring center via the CAN bus.

[0052] The low-temperature battery module provides stable power to the entire system, solving the problem of poor low-temperature discharge performance of traditional batteries. For example... Figure 3 As shown, the low-temperature battery module 2 includes a cell assembly 21, tabs 22, and a smart management BMS system 23. The cell assembly 21 uses lithium nickel cobalt manganese oxide doped with graphene as the positive / negative electrode material, and the electrolyte is a mixed solution of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, with added fluoroethylene carbonate. The tabs 22 are made of copper-plated nickel and are evenly distributed on the cell current collector. The smart management BMS system 23 integrates a voltage sensor 25, a current sensor 26, a temperature sensor 27, and a heating element 24, which can monitor the battery status in real time and automatically adjust the charging and discharging strategy.

[0053] The pressure-resistant shell 3 is made of TC4 titanium alloy with a wall thickness of 15mm. It has an internal nitrile rubber buffer layer and is equipped with 4 double O-ring sealing interfaces, which can withstand 10MPa water pressure.

[0054] The CAN communication storage housing module 4 integrates a CAN communication controller 411, a CAN transceiver 412, a data storage unit 421, and a CRC verification unit 422. The CAN communication controller 411 supports the CAN2.0B protocol with a communication rate of 500kbps. The 421 uses 8GB NAND flash memory and supports dual-zone backup and CRC verification by the CRC verification unit 422.

[0055] The data processing chip 114 uses an STM32H743IIT6 MCU to perform moving average filtering and Kalman filtering preprocessing on the raw data from the gyroscope and accelerometer, and to calibrate the magnetometer data using an ellipse fitting algorithm. The filtering window size is 10 data points. The fusion processing unit 13 is implemented based on an EP4CE10F17C8N FPGA and dynamically allocates the data weights of the two units based on the historical error variance.

[0056] Cell group 21 consists of 4 cells connected in series, with a total voltage of 14.8V and a capacity of 20Ah. In an environment of -40℃, the discharge rate is ≥0.5C, and the continuous discharge time is ≥20 hours. The intelligent management BMS system 23 is built based on an STM32L431RCT6 MCU. It sends a warning signal when the SOC is <20% or the cell temperature is <-35℃ or >45℃. The heating element 24 of the low-temperature battery module 2 has a power of 5W and is controlled by the intelligent management BMS system 23 through a PI algorithm. Heating is activated when the cell temperature is <-35℃ and deactivated when the temperature rises to -30℃ to prevent performance degradation during low-temperature discharge.

[0057] The outer surface of the pressure shell 3 is treated with a micro-arc oxidation coating with a thickness of 10μm. After 5000 hours of salt spray testing, there is no rust. The internal nitrile rubber buffer layer can reduce the external vibration acceleration from 10g to less than 1g.

[0058] In the CAN communication storage module 4, the CAN transceiver 412 adopts the TJA1050 type. The CAN bus uses shielded twisted-pair cable transmission, with 120Ω terminating resistors connected in parallel at both ends. The data transmission error rate is <10. -8 The 8GB NAND flash memory uses the K9F1208U0C model, with a data retention time of ≥10 years, and supports querying and backtracking by time range.

[0059] The structure and function of CAN communication storage shell module 4 are as follows:

[0060] Hardware composition: Based on the SJA1000 CAN controller and TJA1050 CAN transceiver, it supports the CAN2.0A / B protocol and the communication rate is configurable (50kbps~1Mbps, this system is configured to 500kbps); the controller is connected to the dual backup inertial navigation module and the cryogenic battery module through the SPI interface to collect cornering data (frequency 100Hz), inertial navigation status data (frequency 10Hz), and battery status data (frequency 5Hz).

[0061] Data packaging and transmission:

[0062] Data frame structure: CAN2.0B extended frame (29-bit identifier) ​​is used, and the identifier is assigned as follows:

[0063] Corner data frame: 0x18000001, data field 8 bytes (including timestamp 4 bytes, corner value 2 bytes, checksum 2 bytes);

[0064] Inertial navigation status frame: 0x18000002, data field 8 bytes (including 2 bytes of cell status, 2 bytes of zero bias, 2 bytes of error variance, and 2 bytes of checksum);

[0065] Battery status frame: 0x18000003, data field 8 bytes (including SOC 1 byte, voltage 2 bytes, current 2 bytes, temperature 2 bytes, checksum 1 byte);

[0066] Anti-interference measures: The CAN bus uses differential signal transmission, with 120Ω terminating resistors connected in parallel at both ends of the bus to reduce signal reflection; the cable uses shielded twisted pair (the shielding layer is aluminum foil + braided mesh), and the grounding resistance is <1Ω, which can resist electromagnetic interference from the submarine cable laying vessel (EMC testing is based on EN61000-6-2 standard, and the communication bit error rate is <10% under an electric field strength of 10V / m). -8 );

[0067] Command reception: The controller can receive control commands sent by the shipborne monitoring center, such as "system calibration command" (0x28000001), "data query command" (0x28000002), and "restart command" (0x28000003), with a command response time of <100ms.

[0068] Data storage unit:

[0069] Storage medium: Samsung K9F1208U0C NAND flash memory chip, 8GB capacity, erase / write cycle life ≥100,000 times, data retention time ≥10 years (at room temperature); the chip is connected to the CAN communication controller 411 via SPI interface, supporting page programming (2KB / page) and block erasure (128KB / block).

[0070] Storage strategy:

[0071] Real-time storage: All collected data is stored in the format of "timestamp + data type + data content + verification". The storage frequency is consistent with the data acquisition frequency: 100Hz for corner data and 5-10Hz for other data. 8GB capacity can support continuous storage for 6 months. Based on an average daily storage of 400MB: 400MB × 180 days = 72GB. Correction: The actual calculation is: corner data 100 frames / second × 8 bytes / frame = 800 bytes / second, other data 10 frames / second × 8 bytes / frame × 2 (INS + battery) = 160 bytes / second, total rate 960 bytes / second, storage per hour 3.456MB, storage per day 82.944MB, 8GB / 82.944MB ≈ 96 days. After reserving 20% ​​redundancy, it becomes 77 days. This is adjusted to support continuous storage for 2 months.

[0072] Data verification and backup: For each block of data (128KB) stored, a CRC32 check value is calculated and stored together with the data; at the same time, a "dual-zone backup" strategy is adopted - the data is stored in two different block areas of the flash memory (primary storage area and backup storage area). If the data verification in the primary storage area fails, the data in the backup storage area is automatically read to ensure data integrity.

[0073] Data backtracking: Supports sending "data query command" via CAN bus, specifying a time range (accurate to the second), and the storage unit can locate and read the corresponding data within 1 second, and transmit it back to the monitoring center via CAN bus.

[0074] The angle monitoring system is fixed to the submarine cable 1 meter downstream of the cable untwisting device using a specially made 316L stainless steel clamp. The inner diameter of the clamp matches the outer diameter of the submarine cable, and it is tightened with a torque wrench at a torque of 30 N·m to ensure that the system moves synchronously with the submarine cable. Regular maintenance includes daily appearance and function checks, monthly sealing and battery performance checks, and annual pressure shell flaw detection and module calibration. The dual backup inertial navigation module 1 is calibrated quarterly using a high-precision turntable (accuracy ±0.001°) to ensure that the angle measurement error is ≤0.1°.

[0075] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for monitoring the angle of rotation during the release of a submarine cable, characterized in that, It includes a pressure-resistant housing (3), which houses a dual-backup inertial navigation module (1), a cryogenic battery module (2), and a CAN communication storage housing module (4). The dual-backup inertial navigation module (1) includes a first inertial navigation unit (11) and a second inertial navigation unit (12). The first inertial navigation unit (11) and the second inertial navigation unit (12) integrate a high-precision MEMS gyroscope (111), a three-axis accelerometer (112), a three-axis magnetometer (113) and a data processing chip (114). The first inertial navigation unit (11) and the second inertial navigation unit (12) are connected through a fusion processing unit (13). The fusion processing unit (13) uses an unscented Kalman filter algorithm to fuse the preprocessed data of the first inertial navigation unit (11) and the second inertial navigation unit (12). When any inertial navigation unit fails, the other inertial navigation unit can seamlessly switch to work within <10ms. The low-temperature battery module (2) includes a cell assembly (21), a tab (22), and an intelligent management BMS system (23). The cell assembly (21) uses lithium nickel cobalt manganese oxide doped with graphene as the positive / negative electrode material, and the electrolyte is a mixed solution of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, with added fluoroethylene carbonate. The tab (22) is made of copper-plated nickel material and is uniformly distributed on the cell current collector. The intelligent management BMS system (23) integrates a voltage sensor (25), a current sensor (26), a temperature sensor (27), and a heating element (24), which can monitor the battery status in real time and automatically adjust the charging and discharging strategy. The pressure-resistant shell (3) is made of TC4 titanium alloy with a wall thickness of 15mm. It has an internal nitrile rubber buffer layer and four double O-ring sealing interfaces on the pressure-resistant shell (3), which can withstand 10MPa water pressure. The CAN communication storage shell module (4) integrates a CAN communication controller (411), a CAN transceiver (412), a data storage unit (421), and a CRC verification unit (422). The CAN communication controller (411) supports the CAN2.0B protocol with a communication rate of 500kbps. The data storage unit (421) uses 8GB NAND flash memory and supports dual-zone backup and CRC verification unit (422) verification.

2. The angle monitoring system for submarine cable unwinding and release according to claim 1, characterized in that, The data processing chip (114) uses an STM32H743IIT6 MCU to perform moving average filtering and Kalman filtering preprocessing on the raw data of the gyroscope and accelerometer in sequence, and to calibrate the magnetometer data using an ellipse fitting algorithm. The filtering window size is 10 data points. The fusion processing unit (13) is implemented based on an EP4CE10F17C8N FPGA and dynamically allocates the data weights of the two units through the historical error variance.

3. The angle monitoring system for submarine cable unwinding and release according to claim 1, characterized in that, The battery cell group (21) consists of 4 battery cells connected in series, with a total voltage of 14.8V and a capacity of 20Ah; in an environment of -40℃, the discharge rate is ≥0.5C and the continuous discharge time is ≥20 hours; the intelligent management BMS system (23) is built based on the STM32L431RCT6 MCU, and sends a warning signal when the state of charge (SOC) is <20% or the battery cell temperature is <-35℃ or >45℃.

4. The angle monitoring system for submarine cable unwinding and release according to claim 1, characterized in that, The outer surface of the pressure-resistant shell (3) is treated with a micro-arc oxidation coating with a coating thickness of 10μm. After 5000 hours of salt spray testing, there is no rust. The internal nitrile rubber buffer layer can reduce the external vibration acceleration from 10g to less than 1g.

5. The angle monitoring system for submarine cable unwinding and release according to claim 1, characterized in that, The CAN transceiver (412) is a TJA1050 type, and the CAN bus uses shielded twisted-pair cable for transmission. A 120Ω terminating resistor is connected in parallel at both ends, and the data transmission error rate is <10%. -8 The 8GB NAND flash memory uses the K9F1208U0C model, with a data retention time of ≥10 years, and supports querying and backtracking by time range.

6. The angle monitoring system for submarine cable unwinding and release according to claim 1, characterized in that, The dual backup inertial navigation module (1) uses an ADIS16488 gyroscope with a zero bias stability of ≤0.1° / h and an LSM6DSO accelerometer with a resolution of 0.000244g. The magnetometer used is the BMM150 model, with a resolution of 0.3 μT.

7. The angle monitoring system for submarine cable unwinding and release according to claim 1, characterized in that, The angle monitoring system is fixed to the submarine cable 1 meter downstream of the cable untwisting device using a specially made 316L stainless steel clamp. The inner diameter of the clamp matches the outer diameter of the submarine cable. The clamp is tightened with a torque wrench at a torque of 30 N·m to ensure that the system moves synchronously with the submarine cable.

Images