Submarine cable positioning system based on magnetic field detection

Abstract

The invention discloses a submarine cable positioning system based on magnetic field detection. A fluxgate sensor array comprises a plurality of rows of uniformly arranged fluxgate sensors, X-axis magnetic component data, Y-axis magnetic component data and Z-axis magnetic component data of each row of fluxgate sensors convert voltage signals into digital signals through three high-precision analog-to-digital conversion chips in one group, and a main control chip synchronously controls the three high-precision analog-to-digital conversion chips in each group. X-axis, Y-axis and Z-axis magnetic component data of each row of fluxgate sensors are collected, the peak value of magnetic anomaly is regarded as right above the submarine cable, and therefore the relative position of the submarine cable and the submarine cable positioning system is judged. Through the self-developed synchronous acquisition circuit, the data synchronism between fluxgate sensors and between different components of the fluxgate sensors is improved, meanwhile, the data precision of the fluxgate sensors is improved, and the resolution of magnetic field data is improved; and azimuth guidance is provided for underwater cable searching.

Description

Technical Field

[0001] The present invention belongs to the technical field of underwater magnetic measurement, and relates to a submarine cable positioning system based on magnetic field detection. Background Art

[0002] A submarine cable, that is, an ocean cable, is a wire wrapped with insulating material laid on the seabed for international telecommunications, Internet data transmission, or power transmission, and plays an important role in economic development and security construction.

[0003] Due to the requirements of its working environment, compared with ordinary optical cables, submarine cables must ensure that the internal optical fibers can resist seabed pressure, withstand seabed corrosion, and adapt to complex seabed conditions during design. To protect submarine cables, an armor layer is usually wrapped on the outside.

[0004] The armor layer of a submarine cable is usually made of metal wires woven or spirally wound to protect the optical fibers or cables inside the submarine cable. The armor layer is mainly used to resist mechanical damage and chemical corrosion in a complex marine environment. The main core contents include: Mechanical protection: Resisting external force impacts such as seabed pressure, anchor dragging by ships, and rock friction. Anti-corrosion and shielding: Using galvanized layers, asphalt coatings, or polymer sheaths to prevent seawater erosion, and some armor layers can also shield electromagnetic interference through the Faraday cage effect. Elasticity and flexibility: The armor layer has a certain degree of elasticity and flexibility, enabling the submarine cable to adapt to changes in the seabed terrain and reducing stress concentration caused by terrain changes. Therefore, the armor layer of a submarine cable is an important part of protecting the optical fibers or cables inside the submarine cable, and can ensure the long-term stable and reliable operation of the submarine cable in the seabed environment.

[0005] During the laying process of submarine cables, they often pass through main channels or fishing operation areas with busy maritime traffic and numerous ships. This results in that during the process of ship anchoring, submarine cables in some special sections that are exposed or have a shallow burial depth will inevitably be damaged by ship anchors. Therefore, to ensure the stable operation of the interconnected power supply, it is very necessary to effectively avoid the possible ship anchor hazards at any time, and it is of great significance to quickly locate the submarine cables.

[0006] Magnetic field detection, as a relatively novel detection method, has certain applications in metals. Metal materials are magnetized and become magnetic under the influence of the geomagnetic field. Therefore, the magnetic field in the surrounding space of this material is the superposition of the geomagnetic field and the magnetic field generated by this material, manifested as the superposition of the geomagnetic field and the magnetic field generated by this material, manifested as geomagnetic anomalies. Magnetic field detection locates the position of the material by detecting the abnormal distribution characteristics of magnetic signals within a certain spatial range.

[0007] At present, the identification and positioning of submarine cables are mainly carried out from the following two aspects: (1) Manual identification. Long-term and high-intensity manual operations are likely to affect subjective judgment, with low identification accuracy and low identification efficiency. (2) Acoustic detection. Sonar uses the propagation and reflection characteristics of sound waves underwater to detect or locate underwater targets. However, it is easily affected by factors such as seabed disturbances, grooves, and abnormal bottom sediments, and cannot detect buried targets.

[0008] Traditional submarine cable searching methods cannot meet the detection requirements in harsh sea conditions, high turbidity, or special environments such as being buried in soil, lacking an effective means for quickly positioning submarine cables. Since the armor layer of submarine cables is usually composed of ferromagnetic materials, there will be obvious magnetic anomaly signals around it that are different from the geomagnetic field. Through material simulation and actual experiments, it can be known that the magnetic field reaches its peak at the axis and decreases on both sides, reaching the minimum at the edge.

[0009] For the above reasons, the present invention proposes a submarine cable positioning system based on magnetic field detection, which uses at least 10 three-component fluxgate sensors combined in an array form to scan the magnetic field in the underwater area, and sends the collected magnetic field data to the underwater robot in real time. The peak of the magnetic anomaly can be regarded as directly above the submarine cable, and the movement direction of the underwater robot is controlled by observing the change of the data to achieve fast and accurate positioning and searching of the submarine cable. Summary of the Invention

[0010] In order to solve the problems existing in the background technology, the present invention proposes a submarine cable positioning system based on magnetic field detection. By combining at least 10 three-component fluxgate sensors in an array form and through a self-developed synchronous acquisition circuit, the data synchronization between fluxgate sensors and between different components of a single fluxgate sensor is improved.

[0011] The present invention includes a power supply circuit, a signal acquisition circuit, a data processing and transmission circuit, and a fluxgate sensor array. The power supply circuit is used to supply power to the signal acquisition circuit, the data processing and transmission circuit, and the fluxgate sensor array; the signal acquisition circuit is used to convert the analog voltage quantity collected by the fluxgate sensor into a digital quantity; the data processing and transmission circuit is used to control the synchronous acquisition of the signal acquisition circuit, store the collected data, and send it to the host computer through the serial port.

[0012] The signal acquisition circuit includes multiple groups of high-precision analog-to-digital conversion chips, and the data processing and transmission circuit includes a main control chip.

[0013] The fluxgate sensor array includes multiple rows of fluxgate sensors arranged uniformly. For each row of fluxgate sensors, the magnetic component data of the X, Y, and Z axes of the fluxgate sensors are converted from voltage signals to digital signals by a group of 3 high-precision analog-to-digital conversion chips. The synchronous input pins SYNC of each group of 3 high-precision analog-to-digital conversion chips are connected in parallel to the same control pin of the main control chip to synchronously control each group of 3 high-precision analog-to-digital conversion chips. This enables the three analog-to-digital conversion chips in each group to start sampling in the same clock cycle, with a timing deviation not exceeding 1 main clock cycle, achieving multi-channel synchronous acquisition of the fluxgate sensors in the same group.

[0014] The data output pins of each group of 3 high-precision analog-to-digital conversion chips are connected to the I / O pins of the main control chip for data transmission; when the main control chip is powered on, a low level is input at the SYNC pin to trigger the synchronous operation, clear the internal sampling data, and reset the channel sequencer; the rising edge indicates the end of synchronization, and the chip starts collecting new samples from the next main clock falling edge.

[0015] Collect the magnetic component data of the X, Y, and Z axes of each row of fluxgate sensors, and regard the peak of the magnetic anomaly as directly above the submarine cable, thereby judging the relative position between the submarine cable and the submarine cable positioning system.

[0016] Furthermore, the present invention also includes a TTL-to-232 chip for converting the TTL-level serial signal output from the serial port of the main control chip into an RS-232-level serial signal, an LED lamp for displaying the operating status of the main control chip, an AD chip connector for connecting each lead of the fluxgate sensor to the circuit board, a wireless programmer for wirelessly programming the main control chip, a wireless radio for wireless communication with the upper computer, a UWB module for underwater positioning of the fluxgate sensor, a clock module for providing external clock information to the main control chip, and an SD card for storing the data received by the main control chip.

[0017] Furthermore, the power supply circuit includes a 12V output power supply circuit, a -12V output power supply circuit, a +5V output power supply circuit, and a +3.3V output power supply circuit 4. Among them, +12V and -12V are used to supply power to the fluxgate sensor array; among them, +5V is used to supply power to the ultra-wideband UWB positioning module, the wireless programmer, the wireless radio, and the TTL-to-232 module; among them, +3.3V is used to supply power for the normal operation of the single-chip microcomputer.

[0018] Preferably, the +12V output power supply circuit uses the switching power supply chip TPS5430 of Texas Instruments, the -12V output power supply circuit uses the bipolar switched-capacitor voltage converter LT1054 of Texas Instruments, the +5V output power supply circuit uses the TDK15-24S05 power supply chip produced by Tengda Power Company, and the +3.3V output power supply circuit uses the chip with the model A1117-3.3 produced by Yingruixin Electronic Technology Co., Ltd.

[0019] Further, the high-precision analog-to-digital conversion chip has a 24-bit analog-to-digital converter.

[0020] Preferably, the high-precision analog-to-digital conversion chip uses a chip with the model AD4111BCPZ produced by Analog Devices, Inc. The main control chip uses a chip with the model STM32F103VCT6 produced by STMicroelectronics. The fluxgate sensor uses the HSF243-2H3-AAA fluxgate sensor of Xi'an Huashun Measuring Equipment Co., Ltd.

[0021] Further, the fluxgate sensor array includes at least 10 fluxgate sensors. The distance between the left and right sensors is 30 cm, and the distance between the upper and lower sensors is 30 cm.

[0022] By using the submarine cable positioning system of the present invention, by setting a single control pin of the main control chip to control each group of 3 high-precision analog-to-digital conversion chips, any component of each row of fluxgate sensors can be synchronously collected, and the delay between different components is realized to the millisecond-level interval, meeting the needs of the X, Y, and Z three components of the fluxgate sensor; at the same time, the accuracy of the fluxgate sensor data is improved, and the actual resolution achieved is 16 bits with a fluctuation of 5 decimal places; by adopting the layout design of multiple rows of fluxgate sensors, the resolution of the magnetic field data is further improved; the data is saved in the SD card in real time and sent to the upper computer through the serial port, providing azimuth guidance for underwater cable search according to the magnetic field characteristics of the submarine cable armor layer. Description of the Drawings

[0023] Figure 1 It is the overall block diagram of the circuit of the present invention; Figure 2 It is the arrangement schematic diagram of the 10-fluxgate sensor array in the embodiment; Figure 3 It is the overall structure diagram of the power supply circuit of the present invention; Figure 4 It is Figure 3 the circuit diagram of the +12V output power supply circuit in Figure 5 It is Figure 3 the circuit diagram of the -12V output power supply circuit in Figure 6 It is Figure 3 the circuit diagram of the +5V output power supply circuit in Figure 7 It is Figure 3 the circuit diagram of the +3.3V output power supply in Figure 8 It is the circuit diagram of the analog-to-digital conversion circuit in the signal acquisition circuit; Figure 9 It isFigure 1 Circuit diagram of the data processing and transmission circuit Figure 10 Flowchart of the operation of the circuit of the present invention Figure 11 Example (partial) of the magnetic field data collected Figure 12 is Figure 11 Magnetic field heat map presented after the magnetic field data in is processed by MATLAB software, which more intuitively reflects the magnetic anomaly of the submarine cable Specific implementation manners

[0024] The following further details the present invention patent with reference to the accompanying drawings. It should be noted that, without conflict, the embodiments and features in the embodiments of the present application may be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments

[0025] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present application

[0026] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data used can be interchanged under appropriate circumstances so as to describe the embodiments of the present application here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices

[0027] As Figure 1 shown, a submarine cable positioning system based on magnetic field detection includes a power supply circuit I, a signal acquisition circuit II, a data processing and transmission circuit III, and a fluxgate sensor array S. The power supply circuit I is used to supply power to the signal acquisition circuit II, the data processing and transmission circuit III, and the fluxgate sensor array S. The signal acquisition circuit II is used to convert the analog voltage quantity collected by the fluxgate sensor S into a digital quantity. The data processing and transmission circuit III is used to control the synchronous acquisition of the signal acquisition circuit II and store the collected data and send it to the host computer through the serial port

[0028] In this embodiment, the fluxgate sensor array composed of 10 fluxgate sensors and the signal acquisition circuit including 6 analog-to-digital conversion circuits with the same structure are used as examples to further describe this application. As Figure 2 shown, the 10 fluxgate sensors are divided into two rows and evenly arranged on the fixed bracket. The 6 analog-to-digital conversion circuits are divided into two groups. Each of the 3 analog-to-digital conversion circuits in each group of analog-to-digital conversion circuits converts the voltage of the magnetic data of the X, Y, and Z axis components of 5 fluxgate sensors in the same row into digital quantities.

[0029] The voltage output channel of each fluxgate sensor is connected to the corresponding pin of the high-precision analog-to-digital conversion chip AD4111 in one of the analog-to-digital conversion circuits in the signal acquisition circuit.

[0030] In this embodiment, the fluxgate sensors in the upper row are marked as No. 1, No. 2, No. 3, No. 4, and No. 5 from left to right, and the fluxgate sensors in the lower row are respectively No. 6, No. 7, No. 8, No. 9, and No. 10 from left to right. After testing, when the distance between the left and right sensors is 30 cm and the distance between the upper and lower sensors is 30 cm, the overall size can be taken into account and the mutual interference of magnetic field data can be reduced.

[0031] The power supply circuit is responsible for the power supply of the entire signal acquisition system. As Figure 3 shown, the power supply circuit Ⅰ includes a 12V output power supply circuit 1, a -12V output power supply circuit 2, a +5V output power supply circuit 3, and a +3.3V output power supply circuit 4. Among them, +12V and -12V are used to supply power to the fluxgate sensor array; among them, +5V is used to supply power to the ultra-wideband UWB positioning module, wireless programmer, wireless radio, and TTL to 232 module; among them, +3.3V is used to supply power for the normal operation of the single-chip microcomputer.

[0032] As Figure 4 shown, in this embodiment, the +12V output power supply circuit 1 includes a switching power supply chip U2. In this embodiment, the switching power supply chip uses the switching power supply chip TPS5430 of Texas Instruments. The 9th pin and the 6th pin of the switching chip U2 are connected and then grounded; the 7th pin of the switching chip U2, one end of the capacitor C6, and the positive electrode of the electrolytic capacitor C7 are connected and then connected to the +24V power input; the other end of the capacitor C6 and the negative electrode of the electrolytic capacitor C7 are grounded; the 1st pin of the switching chip U2 is connected to the 8th pin of the switching chip U2 and the negative electrode of the Schottky diode D1 through the capacitor C4 and then connected to one end of the inductor L1; the other end of the inductor L1, one end of the electrolytic capacitor C5, one end of the resistor R2, one end of the capacitor C8, and one end of the capacitor C9 are connected and then used as the output end of the +12V output power supply circuit to output +12V power; the 4th pin of the switching chip U2 is connected to the other end of the resistor R2 and then grounded through the resistor R3, and the other end of the capacitor C8 and the other end of the capacitor C9 are grounded.

[0033] The output voltage of the switching power supply chip TPS5430 is set by a resistor divider (R2 and R3) from the output to the VSENSE pin (pin 4) as follows: .

[0034] For any TPS5430, starting from a resistance value of R2 of 10 kΩ; in this embodiment, when the output is +12V, if the resistance value of R2 is 10 kΩ, then the resistance value of R3 is 1.1 kΩ.

[0035] As Figure 5 shown, in this embodiment, the -12V output power supply circuit 2 includes a switching power supply chip U6. In this embodiment, the switching power supply chip uses the bipolar switched-capacitor voltage converter LT1054 of Texas Instruments, which can provide a higher output current and significantly reduce voltage loss, and by adding an external resistor divider, a regulated output can be obtained. The 8th pin of the switching power supply chip U6 is connected to the +12V power output terminal of the +12V output power supply circuit 1; the 2nd pin of the switching power supply chip U6 is connected to the capacitor C16 and then to the 4th pin of the switching power supply chip U6; the 3rd pin of the switching power supply chip U6 is grounded; the 5th pin of the switching power supply chip U6 outputs -12V voltage, and at the same time, the 5th pin of the switching power supply chip U6 is grounded through the capacitor C19.

[0036] As Figure 6 shown, in this embodiment, the +5V output power supply circuit 3 includes a power supply chip U1. In this embodiment, the power supply chip uses the TDK15-24S05 power supply chip produced by Tenda Power Company, which is used for power supply in a distributed power system, isolates the input and output, and has functions of input undervoltage protection, overcurrent protection, and output short-circuit protection self-recovery. The 1st pin of the power supply chip U1 is connected to one end of the thermistor R1 and one end of the capacitor C1. The other end of the thermistor R1 is connected to the +24V input power supply, and the other end of the capacitor C1 is connected to the 2nd pin of the power supply chip U1 and then to GND; the 6th pin of the power supply chip U1 is connected to one end of the capacitor C2 and one end of the capacitor C3 and then serves as the output terminal of the +5V output power supply circuit to output +5V power. The other ends of the capacitor C2, the other end of the capacitor C3, and the 4th pin of the power supply chip U1 are grounded.

[0037] As Figure 7As shown, the +3.3V output power supply circuit 4 includes a linear power supply chip U3. In this embodiment, the linear power supply chip U3 is a chip with the model A1117-3.3 produced by Yingruixin Electronic Technology Co., Ltd. One end of the 3rd pin of the linear power supply chip U3, one end of the capacitor C11, and one end of the capacitor C10 are connected and then connected to the +5V power supply; one end of the 2nd pin of the linear power supply chip U3, one end of the capacitor C12, and one end of the capacitor C13 are connected and then used as the output end of the +3.3V output power supply circuit to output the +3.3V power supply; one end of the 1st pin of the linear power supply chip U3, the other end of the capacitor C10, the other end of the capacitor C11, the other end of the capacitor C12, and the other end of the capacitor C13 are connected to GND.

[0038] As Figure 8 shown, each analog-to-digital conversion circuit includes a high-precision analog-to-digital conversion chip U10. In this example, a high-precision analog-to-digital conversion chip for collecting the magnetic component of the X-axis of a group of fluxgate sensors is used as an example for illustration. The high-precision analog-to-digital conversion chip U10 is a chip with the model AD4111BCPZ produced by Analog Devices, Inc. This chip is a precision 24-bit analog-to-digital converter (ADC), with fluctuations in the 5th decimal place, a maximum channel scan rate of 6.21kSPS, a conversion output rate ranging from 1.25SPS to 31.25kSPS, and an input voltage range of 3.0V to 5.5V, suitable for the general input analog front-end of industrial process control systems.

[0039] One end of the 1st pin of the high-precision analog-to-digital conversion chip U10 is connected to one end of the capacitor C41 and one end of the resistor R25. The other end of the resistor R25, one end of the resistor R23, and one end of the bidirectional breakdown diode D2 are connected and then connected to AGND. The other end of the capacitor C41, the other end of the resistor R23, and the other end of the bidirectional breakdown diode D2 are connected to GND.

[0040] In this embodiment, the X-axis magnetic field signal outputs of the first row of fluxgate sensors numbered 1 to 5 are taken as an example.

[0041] One end of the 3rd pin of the high-precision analog-to-digital conversion chip U10 is connected to one end of the capacitor C44 and one end of the resistor R28; one end of the capacitor C44 is connected to one end of the bidirectional breakdown diode D4 and then grounded; the other end of the resistor R28 is connected to the other end of the bidirectional breakdown diode D4 and then connected to the X-axis magnetic field signal output end X5 of the 5th fluxgate sensor.

[0042] One end of the 4th pin of the high-precision analog-to-digital conversion chip U10 is connected to one end of the capacitor C45 and one end of the resistor R29; one end of the capacitor C45 is connected to one end of the bidirectional breakdown diode D5 and then grounded; the other end of the resistor R29 is connected to the other end of the bidirectional breakdown diode D5 and then connected to the X-axis magnetic field signal output end X4 of the 4th fluxgate sensor.

[0043] Pin 5 of the high-precision analog-to-digital conversion chip U10 is connected to one end of capacitor C48 and one end of resistor R30; one end of capacitor C48 is connected to one end of the bidirectional breakdown diode D6 and then grounded; the other end of resistor R30 is connected to the other end of the bidirectional breakdown diode D6 and then connected to the X-axis magnetic field signal output terminal X3 of the No. 3 fluxgate sensor.

[0044] Pin 26 of the high-precision analog-to-digital conversion chip U10 is connected to one end of capacitor C49 and one end of resistor R31; one end of capacitor C49 is connected to one end of the bidirectional breakdown diode D7 and then grounded; the other end of resistor R31 is connected to the other end of the bidirectional breakdown diode D7 and then connected to the X-axis magnetic field signal output terminal X2 of the No. 2 fluxgate sensor.

[0045] Pin 27 of the high-precision analog-to-digital conversion chip U10 is connected to one end of capacitor C50 and one end of resistor R32; one end of capacitor C50 is connected to one end of the bidirectional breakdown diode D8 and then grounded; the other end of resistor R32 is connected to the other end of the bidirectional breakdown diode D8 and then connected to the X-axis magnetic field signal output terminal X1 of the No. 1 fluxgate sensor.

[0046] Pin 7 of the high-precision analog-to-digital conversion chip U10 is connected to capacitor C40 and then grounded, and pin 11 of the high-precision analog-to-digital conversion chip U10 is connected to resistor R24 and then to GND; Pin 8, pin 30, pin 31, and pin 32 of the high-precision analog-to-digital conversion chip U10 are connected to GND.

[0047] Pin 9 and pin 20 of the high-precision analog-to-digital conversion chip U10 are connected to the +3.3V power supply, and at the same time, capacitor C38 and capacitor C39 are connected in parallel and then to GND.

[0048] Pin 12 of the high-precision analog-to-digital conversion chip U10 is connected to crystal oscillator G2 and then to pin 13 of the high-precision analog-to-digital conversion chip U10. Both ends of crystal oscillator G2 are respectively connected to capacitor C46 and capacitor C47 and then to GND; Pin 14 of the high-precision analog-to-digital conversion chip U10 is connected to pin 31 of the main control chip U7, and one end of resistor R34 is connected in parallel and then to the 3.3V power supply; pin 15 of the high-precision analog-to-digital conversion chip U10 is connected to pin 32 of the main control chip U7, pin 16 of the high-precision analog-to-digital conversion chip U10 is connected to pin 30 of the main control chip U7; pin 17 of the high-precision analog-to-digital conversion chip U10 is connected to resistor R26 and then to pin 29 of the main control chip U7 (the other 5 high-precision analog-to-digital conversion chips are respectively connected to pins 42, 43, 44, 51, and 64 of the main control chip U7).

[0049] Pin 18 of the high-precision analog-to-digital conversion chip U10 is connected to the resistor R35, then to the cathode of the light-emitting diode LED2, and then to the 3.3V power supply; Pin 19 of the high-precision analog-to-digital conversion chip U10 is connected to Pin 63 of the main control chip U7, and one end of the resistor R33 is connected and then to the 3.3V power supply; Pin 22 of the high-precision analog-to-digital conversion chip U10 is connected to the capacitor C42 and then to GND; Pin 21 of the high-precision analog-to-digital conversion chip U10 is connected to GND. A capacitor C52 is connected between Pin 4 and Pin 5 of the high-precision analog-to-digital conversion chip U10; a capacitor C53 is connected between Pin 26 and Pin 27 of the high-precision analog-to-digital conversion chip U10.

[0050] Pin 41 of the high-precision analog-to-digital conversion chip U10 is connected to GND; the remaining pins of the high-precision analog-to-digital conversion chip are all left unconnected.

[0051] As Figure 9 shown, the data processing and transmission circuit includes the main control chip U7. In this example, the main control chip U7 uses a chip with the model STM32F103VCT6 produced by STMicroelectronics; in this example, the TTL-to-232 chip U8 selects the ADM3251EARWZ chip of (Analog Devices) company, which is used to convert the TTL-level serial signal output by the serial port of the main control chip U7 into an RS-232-level serial signal that can be recognized by a computer or the like, so as to achieve the function of serial communication between the main control chip U7 and the host computer; in this example, the LED light selects the 67-23 / R6GHBHC-B05 / 2T type surface-mount diode LED light produced by Beijing Duchengyiguang Electronics Co., Ltd., which will flash when the main control chip U7 normally collects data, and the operating status of the main control chip U7 can be intuitively seen; in this example, the AD chip connector U9 selects the 37-pin micro-rectangular connector aviation plug with the model J30J-37ZKW-J produced by Taishan Pilot Connector Co., Ltd., which is used to connect the respective leads of 10 fluxgate sensors to the circuit board for power supply, signal input, etc.; in this embodiment, the wireless programmer selects the high-speed wireless debugger with the model ATK-HSWLDBG produced by Guangzhou Xingyi Electronic Technology Co., Ltd., which is used to wirelessly burn the program for the main control chip U7; the wireless radio selects the wireless serial port module with the model AS32-TTL-1W produced by Zeyao Technology, which is used to perform wireless communication with the host computer; the UWB module selects the positioning module with the model RTLS1-LD150 produced by Haoru Technology, which is used to perform water positioning on the fluxgate sensors; the clock module selects the real-time clock chip with the model DS1337U produced by Rochester Electronics, which is used to provide external clock information for the main control chip U7; the SD card selects the 8GB SD card with the model SDSDQAB-008G-MK-A produced by Mikefangde, which is used to store the data received by the main control chip U7.

[0052] Pin 1 of the main control chip U7 is connected to the enable pins of one set of 3 high-precision analog-to-digital conversion chips and then connected to the 3.3V power supply through resistor R36; Pin 2 of the main control chip U7 is connected to Pin 3 of the clock module DS1337U+T&R, and after being connected in parallel with resistor R7, it is connected to the 3.3V power supply; Pin 3 of the main control chip U7 is connected to Pin 5 of the clock module DS1337U+T&R, and after being connected in parallel with resistor R5, it is connected to the 3.3V power supply; Pin 4 of the main control chip U7 is connected to Pin 6 of the clock module DS1337U+T&R, and after being connected in parallel with resistor R4, it is connected to the 3.3V power supply; Pins 6, 50, 75, 100, 28, 11, and 22 of the main control chip U7 are connected to the 3.3V power supply, and after being connected in parallel with capacitor C20, they are grounded; Pins 20, 49, 74, 99, 27, 10, and 19 of the main control chip U7 are connected to GND; Pin 21 of the main control chip U7 is connected to the 3.3V power supply.

[0053] Pins 29, 42, 43, 44, 51, and 64 of the main control chip U7 are respectively connected to Pin 17 (enable pin) of 6 high-precision analog-to-digital conversion chips. Pin 98 of the main control chip U7 is connected to Pin 17 of one set of 3 high-precision analog-to-digital conversion chips, and after passing through resistor R22, it is connected to 3.3V; Pin 1 of the main control chip U7 is connected to Pin 17 of another set of 3 high-precision analog-to-digital conversion chips, and after passing through resistor R36, it is connected to the 3.3V power supply; It is used to uniformly control the enabling of each set of 3 high-precision analog-to-digital conversion chips.

[0054] Pin 63 of the main control chip U7 is connected to Pin 19 of one set of 3 high-precision analog-to-digital conversion chips, and after being connected to resistor R8, it is connected to the 3.3V power supply, which is used to uniformly control the synchronization of these 3 high-precision analog-to-digital conversion chips; Pin 67 of the main control chip U7 is connected to Pin 19 of another set of 3 high-precision analog-to-digital conversion chips, and after being connected to resistor R6, it is connected to the 3.3V power supply, which is used to uniformly control the synchronization of the remaining 3 high-precision analog-to-digital conversion chips.

[0055] Pin 30 of the main control chip U7 is connected to Pin 16 of 2 high-precision analog-to-digital conversion chips for measuring the X-axis magnetic component; Pin 31 of the main control chip U7 is connected to Pin 14 of 2 high-precision analog-to-digital conversion chips for measuring the X-axis magnetic component; Pin 32 of the main control chip U7 is connected to Pin 15 of 2 high-precision analog-to-digital conversion chips for measuring the X-axis magnetic component; Pin 89 of the main control chip U7 is connected to Pin 16 of 2 high-precision analog-to-digital conversion chips for measuring the Z-axis magnetic component; Pin 90 of the main control chip U7 is connected to Pin 14 of 2 high-precision analog-to-digital conversion chips for measuring the Z-axis magnetic component; Pin 91 of the main control chip U7 is connected to Pin 15 of the high-precision analog-to-digital conversion chip for measuring the Z-axis magnetic component; Pin 52 of the main control chip U7 is connected to pin 16 of two high-precision analog-to-digital conversion chips for measuring the magnetic component of the Y-axis; pin 53 of the main control chip U7 is connected to pin 14 of two high-precision analog-to-digital conversion chips for measuring the magnetic component of the Y-axis; pin 54 of the main control chip U7 is connected to pin 15 of two high-precision analog-to-digital conversion chips for measuring the magnetic component of the Y-axis.

[0056] At the same time, the main control chip U7 controls the switching of two groups of high-precision analog-to-digital conversion chips (pins 30, 89, and 52 of the main control chip U7 are connected to a group of three high-precision analog-to-digital conversion chips each time), and the time is in the millisecond level, effectively improving the data synchronization between different components of a single fluxgate sensor.

[0057] Pin 68 of the main control chip U7 is connected to pin 7 of the wireless programming connector S2; pin 69 of the main control chip U7 is connected to pin 5 of the wireless programming connector S2; pin 72 of the main control chip U7 is connected to pin 6 of the wireless programming connector S2; pin 76 of the main control chip U7 is connected to pin 8 of the wireless programming connector S2.

[0058] Pin 65 of the main control chip U7 is connected to pin 7 of the SD card SD1, and after connecting the resistor R9, it is connected to 3.3V; pin 66 of the main control chip U7 is connected to pin 8 of the SD card SD1; pin 80 of the main control chip U7A is connected to pin 5 of the SD card SD1, and pin 83 of the main control chip U7 is connected to pin 3 of the SD card module, and after connecting the parallel resistor R10, it is connected to the 3.3V power supply.

[0059] Pin 78 of the main control chip U7A is connected to pin 3 of the radio connector S3; pin 79 of the main control chip U7A is connected to pin 4 of the radio connector S3.

[0060] Pin 47 of the main control chip U7 is connected to pin 3 of the UWB positioning module connector S1; pin 48 of the main control chip U7 is connected to pin 5 of the UWB positioning module connector S1.

[0061] Pin 86 of the main control chip U7 is connected to pin 9 of the TTL-to-232 chip U8 after connecting the series resistor R18; pin 87 of the main control chip U7 is connected to pin 8 of the TTL-to-232 U8 chip after connecting the series resistor R16.

[0062] Pin 60 of the main control chip U7 is connected to the RED of the LED light; pin 61 of the main control chip U7 is connected to the GREEN of the LED light; pin 62 of the main control chip U7 is connected to the BLUE of the LED light; Pins 12 and 13 of the main control chip U7 are respectively connected to both ends of the crystal oscillator G1; pin 94 of the main control chip U7 is connected to the download button BOOT0; pin 14 of the main control chip U7 is connected to the reset button NRST. The remaining pins of the main control chip U7 are left vacant.

[0063] In this embodiment, the HSF243-2H3-AAA fluxgate sensor of Xi'an Huashun Measuring Equipment Co., Ltd. is used. The 5th to 7th pins of this sensor are for three-axis voltage output, and each voltage output channel is connected to the corresponding pins of its respective high-precision analog-to-digital conversion chips (all AD4111) through the AD chip connector U9.

[0064] As Figure 10 shown, the working process of the above system is as follows: Each voltage output channel is connected to the corresponding pins of its respective high-precision analog-to-digital conversion chip: The first high-precision analog-to-digital conversion chip (AD4111-1) collects the X-component magnetic data of the 1st to 5th magnetic probes, the second high-precision analog-to-digital conversion chip (AD4111-2) collects the Y-component magnetic data of the 1st to 5th magnetic probes, the third high-precision analog-to-digital conversion chip (AD4111-3) collects the Z-component magnetic data of the 1st to 5th magnetic probes, the fourth high-precision analog-to-digital conversion chip (AD4111-4) collects the X-component magnetic data of the 6th to 10th magnetic probes, the fifth high-precision analog-to-digital conversion chip (AD4111-5) collects the Y-component magnetic data of the 6th to 10th magnetic probes, and the sixth high-precision analog-to-digital conversion chip (AD4111-6) collects the Z-component magnetic data of the 6th to 10th magnetic probes.

[0065] The 14th pin (DOUT data output pin) of each high-precision analog-to-digital conversion chip is connected to the I / O pin of the STM32 single-chip microcomputer for data transmission. The STM32 single-chip microcomputer controls the 19th pin (SYNC) of AD4111-1, AD4111-2, and AD4111-3 through its 63rd pin (CONTROL1_2_3) to synchronize the above three AD4111s. The overall working process is as follows: When the STM32 single-chip microcomputer is powered on, it pulls down the SYNC pin, and the above AD4111-1, AD4111-2, and AD4111-3 will enter the synchronization mode. At this time, no data will be read out. After waiting for 1 second, the STM32 single-chip microcomputer pulls up the CONTROL1_2_3 pin, and the above AD4111-1, AD4111-2, and AD4111-3 start to collect voltage data. At the same time, the collected voltage data is transmitted to the STM32 single-chip microcomputer through the SPI bus. The above AD4111-1, AD4111-2, and AD4111-3 transmit data through SPI1, SPI2, and SPI3, and the data is transmitted to the on-chip Flash of the STM32, improving the synchronization of multi-channel data acquisition of the 1st to 5th fluxgate sensors arranged side by side; The STM32 single-chip microcomputer controls the 19th pin (SYNC) of AD4111-4, AD4111-5, and AD4111-6 through its 67th pin (CONTROL4_5_6) to synchronize the above three AD4111s. When the STM32 single-chip microcomputer is powered on, it pulls down the SYNC pin, and the above AD4111-4, AD4111-5, and AD4111-6 will enter the synchronization mode. At this time, no data will be read out. After waiting for 1 second, the STM32 single-chip microcomputer pulls up the CONTROL4_5_6 pin, and the above AD4111-4, AD4111-5, and AD4111-6 start to collect voltage data. At the same time, the collected voltage data is transmitted to the STM32 single-chip microcomputer through the SPI bus. The above AD4111-4, AD4111-5, and AD4111-6 transmit data through SPI1, SPI2, and SPI3, and the data is transmitted to the on-chip Flash of the STM32, improving the synchronization of multi-channel data acquisition of the 6th to 10th fluxgate sensors arranged side by side.

[0066] The 86th and 87th pins of the STM32 are connected to the 8th and 9th pins of the chip ADM3251EARWZ, and the magnetic field data stored in the on-chip Flash of the STM32 is converted into RS232 level and sent to the host computer through serial port 2.

[0067] During use, the submarine cable positioning system is installed on the underwater robot. Onshore operators determine the relative position of the submarine cable and the underwater robot (submarine cable positioning system) based on the magnetic field data displayed by the host computer, and control the underwater robot's movement to conduct underwater cable search. Specifically, the peak of the magnetic anomaly can be considered to be directly above the submarine cable. The direction of the underwater robot's movement is controlled by observing changes in the data (for example, if the magnetic field value of the right fluxgate sensor is higher than that of the left, the submarine cable is judged to be to the right of the underwater robot. At this time, the underwater robot needs to be controlled to move to the right until the magnetic field data collected by the middle fluxgate sensor reaches the highest value of all fluxgate sensors, which can determine that the submarine cable is directly below the underwater robot), achieving fast and accurate submarine cable positioning and search.

[0068] In actual engineering, the two rows of collected magnetic field signals can be displayed in real time on the host computer. In this embodiment, the distance between the front and rear rows of sensors is 30 cm. During the collection process, it is equivalent to sampling the same route twice, which in effect doubles the sampling rate of the equipment to prevent the loss of some magnetic anomaly data due to the excessive speed of the underwater robot; it also improves the sampling rate and the resolution of the collected magnetic field data.

[0069] The submarine cable positioning system designed in this embodiment is installed on an underwater robot (any underwater robot can be used), as shown in FIG. Figure 11 The following is a partial list of actual data from an underwater cable search experiment. The M in the first column stands for magnetic field. Thereafter, every three columns form a group, totaling 10 groups. From left to right, they are groups 1 to 10, each representing the magnetic field data collected by the fluxgate sensor with that number. Each group is divided into three columns, representing the magnetic field data in the X, Y, and Z directions of the fluxgate sensor with that number. The data received by the microcontroller is a voltage value in volts, with 5 decimal places. Multiplying it by 10,000 gives Figure 11 The magnetic field value presented is in txt format and the unit is nanoT.

[0070] In order to more intuitively see the effect of the submarine cable positioning system based on magnetic field detection described in this article, Figure 12 As shown in the figure, Figure 11 The magnetic field data from the area was processed using MATLAB software (the raw data was filtered, interpolated, and normalized; the data for the front and back rows was processed by adding or subtracting 30 cm along the Y axis). This results in a regional magnetic field heat map. The horizontal axis represents the X-axis coordinate of the area, the vertical axis represents the Y-axis coordinate, the right legend represents the magnetic field modulus, the center main image represents the magnetic field heat map of the area, and the white curved line represents a schematic diagram of the underwater cable. The image shows that the underwater robot is directly above the cable, demonstrating that the submarine cable positioning system based on magnetic field detection described in this article can achieve underwater cable locating.

Claims

1. A submarine cable positioning system based on magnetic field detection, characterized in that: It includes a power supply circuit, a signal acquisition circuit, a data processing and transmission circuit, and a fluxgate sensor array; the power supply circuit is used to supply power to the signal acquisition circuit, the data processing and transmission circuit, and the fluxgate sensor array; The signal acquisition circuit is used to convert the analog voltage quantity collected by the fluxgate sensor into a digital quantity; the data processing and transmission circuit is used to control the synchronous acquisition of the signal acquisition circuit and store the collected data and send it to the host computer through the serial port; The signal acquisition circuit includes multiple groups of high-precision analog-to-digital conversion chips, and the data processing and transmission circuit includes a main control chip; The fluxgate sensor array includes multiple rows of fluxgate sensors arranged evenly. The X, Y, and Z axis magnetic component data of the fluxgate sensors in each row of fluxgate sensors are converted into digital signals by a group of 3 high-precision analog-to-digital conversion chips. The synchronous input pins SYNC of each group of 3 high-precision analog-to-digital conversion chips are connected in parallel to the same control pin of the main control chip to synchronously control each group of 3 high-precision analog-to-digital conversion chips; so that the three analog-to-digital conversion chips in each group start sampling in the same clock cycle, and the timing deviation does not exceed 1 main clock cycle, realizing multi-channel synchronous acquisition of the fluxgate sensors in the same group; The data output pins of each group of 3 high-precision analog-to-digital conversion chips are connected to the I / O pins of the main control chip for data transmission; when the main control chip is powered on, a low level is input at the SYNC pin to trigger the synchronous operation, clear the internal sampling data, and reset the channel sequencer; the rising edge indicates the end of synchronization, and the chip starts collecting new samples from the next main clock falling edge; Collect the X, Y, and Z axis magnetic component data of each row of fluxgate sensors, and regard the peak of the magnetic anomaly as directly above the submarine cable, so as to judge the relative position between the submarine cable and the submarine cable positioning system.

2. The submarine cable positioning system based on magnetic field detection according to claim 1, wherein: It also includes a TTL-to-232 chip for converting the TTL level serial signal output by the main control chip's serial port into an RS-232 level serial signal, an LED lamp for displaying the operating status of the main control chip, an AD chip connector for connecting each lead of the fluxgate sensor to the circuit board, a wireless programmer for wirelessly programming the main control chip, a radio station for wireless communication with the host computer, a UWB module for underwater positioning of the fluxgate sensor, a clock module for providing external clock information to the main control chip, and an SD card for storing the data received by the main control chip.

3. The submarine cable positioning system based on magnetic field detection according to claim 2, characterized in that: The power supply circuit includes a 12V output power supply circuit, a -12V output power supply circuit, a +5V output power supply circuit, and a +3.3V output power supply circuit 4; among them, +12V and -12V are used to supply power to the fluxgate sensor array; among them, +5V is used to supply power to the ultra-wideband UWB positioning module, the wireless programmer, the radio station, and the TTL-to-232 module; among them, +3.3V is used to supply power for the normal operation of the single-chip microcomputer.

4. The submarine cable positioning system based on magnetic field detection according to claim 1, characterized in that: The high-precision analog-to-digital conversion chip has a 24-bit analog-to-digital converter.

5. The submarine cable positioning system based on magnetic field detection according to claim 1, characterized in that: The high-precision analog-to-digital conversion chip adopts the chip with the model AD4111BCPZ produced by Analog Devices, Inc.

6. The submarine cable positioning system based on magnetic field detection according to claim 1, characterized in that: The main control chip adopts the chip with the model STM32F103VCT6 produced by STMicroelectronics.

7. The submarine cable positioning system based on magnetic field detection according to claim 1, wherein: The described fluxgate sensor array includes at least 10 fluxgate sensors.

8. The submarine cable positioning system based on magnetic field detection according to claim 1 or 8, characterized in that: The distance between the left and right sensors is 30 cm, and the distance between the upper and lower sensors is 30 cm.

9. The submarine cable positioning system based on magnetic field detection according to claim 1, characterized in that: The described fluxgate sensors use the HSF243-2H3-AAA fluxgate sensors of Xi'an Huashun Measuring Equipment Co., Ltd.

10. The submarine cable positioning system based on magnetic field detection according to claim 2, wherein: The +12V output power supply circuit uses the switching power supply chip TPS5430 of Texas Instruments. The -12V output power supply circuit uses the bipolar switched-capacitor voltage converter LT1054 of Texas Instruments. The +5V output power supply circuit uses the TDK15-24S05 power supply chip produced by Tengda Power Company. The +3.3V output power supply circuit uses the chip with the model number A1117-3.3 produced by Yingruixin Electronic Technology Co., Ltd.

Images