阅读说明：本技术 一种海底缆线电磁探测系统及自主水下机器人装备 (Submarine cable electromagnetic detection system and autonomous underwater robot equipment ) 是由 向先波 张嘉磊 向巩 张琴 杨少龙 徐国华 于 2020-12-31 设计创作，主要内容包括：本发明属于海洋工程与技术领域,涉及一种海底缆线电磁探测系统及自主水下机器人装备。该系统包括两套三轴电磁探测传感器、一套双输入/单输出水密采集主机、一套水下组合导航定位单元和一套磁探测节点控制器。两套三轴电磁探测传感器采集获取海底缆线探测信号并传给水密采集主机。水密采集主机用于接收两套三轴电磁探测传感器采集的原始电磁信号,并输出至磁探测节点控制器。水下组合导航定位单元用于提供机器人的实时位置、姿态、速度信息。磁探测节点控制器用于根据原始电磁信号和机器人位置进行海底线缆定位。本发明所提供的海底缆线电磁探测用自主水下机器人方案为通用设计方案,可为海底缆线电磁探测装备的总体设计和实施提供指导。(The invention belongs to the field of ocean engineering and technology, and relates to a submarine cable electromagnetic detection system and an autonomous underwater robot device. The system comprises two sets of three-axis electromagnetic detection sensors, a set of double-input/single-output watertight collection host, a set of underwater combined navigation positioning unit and a set of magnetic detection node controller. Two sets of three-axis electromagnetic detection sensors acquire submarine cable detection signals and transmit the submarine cable detection signals to the water density acquisition host. The watertight collection host is used for receiving original electromagnetic signals collected by the two sets of three-axis electromagnetic detection sensors and outputting the original electromagnetic signals to the magnetic detection node controller. The underwater combined navigation positioning unit is used for providing real-time position, attitude and speed information of the robot. And the magnetic detection node controller is used for positioning the submarine cable according to the original electromagnetic signal and the position of the robot. The autonomous underwater robot scheme for electromagnetic detection of submarine cables is a general design scheme, and can provide guidance for overall design and implementation of submarine cable electromagnetic detection equipment.)

1. An electromagnetic submarine cable detection system for carrying a robot for submarine cable electromagnetic detection, comprising: the system comprises a No. 1 three-axis electromagnetic detection sensor, a No. 2 three-axis electromagnetic detection sensor, a watertight collection host, an underwater combined navigation positioning unit and a magnetic detection node controller;

the No. 1 three-axis electromagnetic detection sensor and the No. 2 three-axis electromagnetic detection sensor are symmetrically arranged on two sides of the carrying equipment and are connected with the watertight collection host; the X/Y/Z three axes of the No. 1 and No. 2 three-axis electromagnetic detection sensors are respectively parallel to the X/Y/Z three axes of the coordinate system of the robot, and the X-Y plane of the No. 1 and No. 2 three-axis electromagnetic detection sensors is superposed with the X-Y plane of the coordinate system of the robot appendage;

the watertight collection host is used for receiving the original electromagnetic signals collected by the No. 1 and No. 2 triaxial electromagnetic detection sensors and outputting the original electromagnetic signals to the magnetic detection node controller;

the underwater combined navigation positioning unit is used for providing real-time position, attitude and speed information of the robot and comprises an inertial navigation module, a Doppler velocimeter, an altimeter, a depth meter and a Beidou/GPS positioning module; the X/Y/Z three axes of the inertial navigation module correspond to the X/Y/Z three axes of the coordinate system of the robot respectively; the Doppler velocimeter and the altimeter are parallel to and perpendicular to the Z axis of the robot, and the altimeter is arranged at the position of a central point between the No. 1 and No. 2 three-axis electromagnetic detection sensors; the depth meter is arranged at the bottom of the robot; the Beidou/GPS positioning module is arranged in the robot;

in the underwater combined navigation positioning unit, the longitude and latitude of the robot are converted from the position of the inertial navigation module to the longitude and latitude (N) of the central point between the No. 1 and No. 2 three-axis electromagnetic detection sensors_mid，E_mid)：

(N_mid，E_mid)＝(N_AUV+DcosθcosΨ，E_AUV+DcosθsinΨ)

Wherein D is the horizontal distance between the action center point of the inertial navigation module and the center points of No. 1 and No. 2 triaxial electromagnetic detection sensors, (N)_AUV，E_AUV) The three-axis electromagnetic detection sensors No. 1 and No. 2 are the same as the robot in course, roll angle and pitch attitude angle, and are psi,And θ;

the magnetic detection node controller is used for calculating the position of the submarine cable relative to the robot according to the original electromagnetic signal and calculating the actual spatial position of the submarine cable by combining the real-time position of the robot.

2. The electromagnetic submarine cable detection system according to claim 1, further comprising a navigation/electromagnetic detection synchronization controller for synchronizing data output of the watertight collection host, the inertial navigation module, the altimeter and the depth meter, and maintaining time consistency of data output, thereby ensuring that corresponding timestamps are synchronized during data processing and data storage.

3. The electromagnetic detection system of submarine cables according to claim 1 or 2, wherein the magnetic detection node controller is further configured to collect and receive feedback signals of each sensor or module, perform preprocessing such as filtering and fusion of raw signals, perform time-frequency transformation on electromagnetic detection signals, and store data.

4. An autonomous underwater robot apparatus for submarine cable electromagnetic surveying, characterized in that a submarine cable electromagnetic surveying system according to any of claims 1-3 is carried.

5. The autonomous underwater robotic equipment for submarine cable electromagnetic surveying of claim 4 comprising a bow section, a non-watertight cabin section, a watertight cabin section, an inertial navigation cabin section, an energy battery cabin section, a stern section and a stern thruster connected in series end to end;

a pair of bow wing plates are symmetrically arranged on two sides of the non-watertight cabin section, and the No. 1 and No. 2 three-axis electromagnetic detection sensors are symmetrically arranged on the pair of bow wing plates; the watertight acquisition host body is in a watertight form, and the watertight acquisition host, the Doppler velocimeter and the altimeter are arranged in the nonwatertight cabin section; the underwater integrated navigation positioning unit is arranged in the inertial navigation cabin section, and the depth gauge is arranged at the bottom of the inertial navigation cabin section; the Beidou/GPS positioning module adopts a double-antenna form, and the two antennas are respectively arranged at the bow part and the stern part of the watertight cabin section.

6. An autonomous underwater robotic equipment for electromagnetic surveying of submarine cables according to claim 5 where the stern thruster number is one.

7. An autonomous underwater robot installation for electromagnetic exploration of submarine cables according to claim 5 characterized in that the energy battery is installed at the stern of the watertight bay, so as to guarantee the robot barycenter and the buoyancy center substantially on the same axis by optimizing the length ratio of the fore and aft nonwatertight bays of the robot and configuring the installation position of the nonwatertight bay sensors.

8. An autonomous underwater robot apparatus for electromagnetic surveying of submarine cables according to any of claims 4 to 7 where the robot apparatus is low electromagnetic radiator in its entirety and is designed for electromagnetic isolation at the robot population level and electromagnetic shielding at the system and critical component level.

9. An autonomous underwater robotic device for electromagnetic surveying of submarine cables according to claim 8 where all parts on the wing plate of the bow are machined from non-metallic materials or are non-metallic standard parts; the energy battery in the energy battery cabin section is in a lithium battery pack form, the outer side of the battery pack is coated with pig iron with high magnetic conductivity and brass with high electric conductivity from inside to outside, and the low-frequency electromagnetic wave of the battery pack is reduced from radiating outwards by adopting a plurality of layers of electromagnetic shielding materials; the driver of the propeller is positioned in the watertight cabin body, and the outer layer of the driver body is coated with pig iron with high magnetic conductivity and brass with high electric conductivity from inside to outside; the outer layer of a propulsion motor of the propeller is coated by iron foil paper, and the shell of the propeller body is a watertight metal shell; the watertight cabin section is a metal cabin section and is made of aluminum alloy, a plurality of layers of active electromagnetic shielding materials are arranged in the watertight cabin section, and metal coating processing is carried out on the inner wall of the watertight cabin section.

Technical Field

The invention belongs to the field of ocean engineering and technology, particularly relates to the field of underwater vehicle equipment and submarine cable maintenance, relates to a submarine cable electromagnetic detection system and autonomous underwater robot equipment, and more particularly relates to autonomous underwater robot equipment for submarine cable electromagnetic detection.

Background

The submarine cable mainly comprises a submarine cable, a submarine optical cable and a submarine photoelectric composite cable. The submarine cable system is large in scale, the total length exceeds 120 kilometers, the average annual failure frequency reaches 250 times, and the maintenance rate of the submarine cable per 1000 kilometers is basically about 0.2 time, so that the maintenance demand of the submarine cable is huge. Early submarine cable detection operation depends on a professional diver to perform shallow water area detection and deep water saturation diving operation, and at present, partial submarine cable detection engineering cases still depend on the diver to perform diving operation. The submarine cable detection operation is carried out by depending on divers, on one hand, the operation water depth is limited, and on the other hand, the long-term diving operation has higher physiological damage to the divers. With the development of underwater equipment technology and the increase of underwater detection requirements, the remote control underwater robot technology is gradually mature and widely applied to underwater detection engineering practice. Most of the existing submarine cable detection depends on remote control underwater robot equipment, detection information is uploaded to an engineering mother ship in real time through an umbilical cable, and remote control operation of an upper computer and submarine cable target identification are carried out by professional technicians. Although the submarine cable detection mode depending on the remote control underwater robot expands the detection water depth, the submarine cable detection method has high dependence on a mother ship of an engineering and large human resource consumption on one hand. In recent years, with the development of intelligent control technology, autonomous underwater robots have been widely studied and gradually put into the field of underwater exploration. The autonomous underwater robot greatly gets rid of the dependence of an underwater detection operation process on a mother engineering ship and professional technicians.

Submarine cables are laid under the seabed and often break, damage and other faults occur due to the influence of natural and human activities. Therefore, daily inspection on submarine cables needs to be carried out by means of an underwater vehicle, position data of the submarine cables after the submarine cables change along with the topography of the submarine topography are updated, and guidance basis can be provided for fishing and maintenance of the submarine cables. Because the submarine cable system is large in scale, the remote control underwater robot is difficult to detect in a large sea area at one time, and therefore the autonomous underwater robot is an ideal platform carrier for realizing efficient detection and tracking of submarine cables. Submarine cables are relatively small in size and lay beneath the seabed, so underwater electromagnetic detection is an ideal means for performing submarine cable tracking detection. The underwater electromagnetic detection technology has higher requirements on the aspects of the configuration, the electromagnetic compatibility and the like of the autonomous underwater robot equipment, so that the integration of the submarine cable electromagnetic detection technology and the autonomous underwater robot equipment is still a technical problem.

Disclosure of Invention

Aiming at the defects or improvement requirements in the prior art, the invention provides an electromagnetic detection system for submarine cables and autonomous underwater robot equipment, provides a set of overall design scheme of autonomous underwater robot equipment which is in accordance with ocean engineering practice and has higher intelligent degree for operation maintenance personnel and equipment research personnel of submarine cable systems, and aims to accurately detect a radiation space electromagnetic field of submarine cables and realize automatic tracking detection of submarine cables based on the designed autonomous underwater robot for submarine cable detection.

To achieve the above object, according to one aspect of the present invention, there is provided a submarine cable electromagnetic surveying system for loading on a robot to perform submarine cable electromagnetic surveying, comprising: the system comprises a No. 1 three-axis electromagnetic detection sensor, a No. 2 three-axis electromagnetic detection sensor, a watertight collection host, an underwater combined navigation positioning unit and a magnetic detection node controller;

the No. 1 three-axis electromagnetic detection sensor and the No. 2 three-axis electromagnetic detection sensor are symmetrically arranged on two sides of the carrying equipment and are connected with the watertight collection host; the X/Y/Z three axes of the No. 1 and No. 2 three-axis electromagnetic detection sensors are respectively parallel to the X/Y/Z three axes of the coordinate system of the robot, and the X-Y plane of the No. 1 and No. 2 three-axis electromagnetic detection sensors is superposed with the X-Y plane of the coordinate system of the robot appendage;

the watertight collection host is used for receiving the original electromagnetic signals collected by the No. 1 and No. 2 triaxial electromagnetic detection sensors and outputting the original electromagnetic signals to the magnetic detection node controller;

the underwater combined navigation positioning unit is used for providing real-time position, attitude and speed information of the robot and comprises an inertial navigation module, a Doppler velocimeter, an altimeter, a depth meter and a Beidou/GPS positioning module; the X/Y/Z three axes of the inertial navigation module correspond to the X/Y/Z three axes of the coordinate system of the robot respectively; the Doppler velocimeter and the altimeter are parallel to and perpendicular to the Z axis of the robot, and the altimeter is arranged at the position of a central point between the No. 1 and No. 2 three-axis electromagnetic detection sensors; the depth meter is arranged at the bottom of the robot; the Beidou/GPS positioning module is arranged in the robot;

in the underwater combined navigation positioning unit, the longitude and latitude of the robot are converted from the position of the inertial navigation module to the longitude and latitude (N) of the central point between the No. 1 and No. 2 three-axis electromagnetic detection sensors_mid，E_mid)：

(N_mid，E_mid)＝(N_AUV+D cosθcosΨ，E_AUV+D cosθsinΨ)

Wherein D is the horizontal distance between the action center point of the inertial navigation module and the center points of No. 1 and No. 2 triaxial electromagnetic detection sensors, (N)_AUV，E_AUV) The three-axis electromagnetic detection sensors No. 1 and No. 2 are the same as the robot in course, roll angle and pitch attitude angle, and are psi,And θ;

the magnetic detection node controller is used for calculating the position of the submarine cable relative to the robot according to the original electromagnetic signal and calculating the actual spatial position of the submarine cable by combining the real-time position of the robot.

Furthermore, the system also comprises a navigation/electromagnetic detection synchronous controller which is used for synchronizing the data output of the watertight collection host, the inertial navigation module, the altimeter and the depth meter and keeping the time consistency of the data output, thereby ensuring that the corresponding timestamps are synchronous when the data are processed and stored.

Furthermore, the magnetic detection node controller is also used for collecting and receiving feedback signals of each sensor or module, performing preprocessing such as filtering and fusion of original signals, performing time-frequency transformation on electromagnetic detection signals, and storing data.

To achieve the above object, according to another aspect of the present invention, there is provided an autonomous underwater robotic equipment for electromagnetic exploration of submarine cables, carrying a submarine cable electromagnetic exploration system as described in any one of the preceding claims.

Further, the device comprises a bow section, a non-watertight cabin section, a watertight cabin section, an inertial navigation cabin section, an energy battery cabin section, a stern section and a stern propeller which are sequentially connected end to end;

a pair of bow wing plates are symmetrically arranged on two sides of the non-watertight cabin section, and the No. 1 and No. 2 three-axis electromagnetic detection sensors are symmetrically arranged on the pair of bow wing plates; the watertight acquisition host body is in a watertight form, and the watertight acquisition host, the Doppler velocimeter and the altimeter are arranged in the nonwatertight cabin section; the underwater integrated navigation positioning unit is arranged in the inertial navigation cabin section, and the depth gauge is arranged at the bottom of the inertial navigation cabin section; the Beidou/GPS positioning module adopts a double-antenna form, and the two antennas are respectively arranged at the bow part and the stern part of the watertight cabin section.

Further, the stern thruster is one in number.

Further, the energy battery pack is installed at the stern of the watertight cabin section, so that the gravity center and the floating center of the robot are basically located on the same axis by optimizing the length ratio of the bow to the non-watertight cabin section of the stern of the robot and configuring the installation position of a sensor of the non-watertight cabin section.

Furthermore, the whole robot equipment is a low electromagnetic radiator, electromagnetic isolation design is carried out on the whole robot equipment, and electromagnetic shielding design is carried out on the system and key part level.

Furthermore, all parts on the wing plate of the bow part are processed by adopting non-metallic materials or non-metallic standard parts; the energy battery in the energy battery cabin section is in a lithium battery pack form, the outer side of the battery pack is coated with pig iron with high magnetic conductivity and brass with high electric conductivity from inside to outside, and the low-frequency electromagnetic wave of the battery pack is reduced from radiating outwards by adopting a plurality of layers of electromagnetic shielding materials; the driver of the propeller is positioned in the watertight cabin body, and the outer layer of the driver body is coated with pig iron with high magnetic conductivity and brass with high electric conductivity from inside to outside; the outer layer of a propulsion motor of the propeller is coated by iron foil paper, and the shell of the propeller body is a watertight metal shell; the watertight cabin section is a metal cabin section and is made of aluminum alloy, a plurality of layers of active electromagnetic shielding materials are arranged in the watertight cabin section, and metal coating processing is carried out on the inner wall of the watertight cabin section.

In general, compared with the prior art, the above technical solution contemplated by the present invention can obtain the following beneficial effects:

1. the invention designs the submarine cable electromagnetic detection autonomous underwater robot equipment, can replace the existing remote control underwater robot in engineering practice to search, position and track submarine cables in a large-scale sea area, and has the advantages of low dependence on guarantee conditions of engineering mother ships, technicians and the like, high efficiency, energy conservation, environmental protection and the like.

2. The designed submarine cable electromagnetic detection system and the installation mode thereof provide a complete submarine cable electromagnetic detection system design and construction scheme, and the submarine cable electromagnetic detection system can be carried on designed autonomous underwater robot equipment, and a simplified system (an underwater combination navigation system) can be carried on various underwater carrier platforms such as a remote control underwater robot, a hybrid underwater robot and the like.

3. Aiming at autonomous underwater robot equipment for electromagnetic detection of submarine cables, the invention designs an overall scheme of an autonomous underwater robot which is additionally provided with a bow port/starboard symmetrical streamline long wing plate, carries a submarine cable electromagnetic detection system and has electromagnetic compatibility. The design of the electromagnetic compatibility of the autonomous underwater robot comprises optimization of energy cabin section configuration, active electromagnetic shielding of a watertight cabin section, active electromagnetic shielding of an energy battery and a propeller, a long bow wing carrying mode of an electromagnetic detection sensor and non-ferromagnetic part design around the electromagnetic detection sensor, so that the electromagnetic radiation intensity generated by the autonomous robot body can be reduced to the greatest extent, and the interference on a submarine cable radiation electromagnetic field is reduced to the greatest extent.

4. The autonomous underwater robot driving system comprises a single stern propeller, a double fore-aft elevator and a single stern rudder, and can reduce electromagnetic radiation generated by the robot driving system, improve the horizontal navigation stability and the depth navigation maneuverability of the robot, meet the near-bottom navigation electromagnetic detection requirement of the robot and the actual condition that a submarine cable is locally linear, namely meet the requirements of actual detection working conditions on the vertical high maneuverability and the horizontal high stability of the robot.

Drawings

FIG. 1 is a general outline of an autonomous underwater robotic apparatus for electromagnetic surveying of submarine cables according to the invention;

FIG. 2 is a communication topology diagram of a magnetic detection system of an autonomous underwater robot for submarine cable detection;

FIG. 3 is three views of a robot magnetic detection non-watertight cabin section, wherein (a) - (c) are respectively a front view, a side view and a top view;

FIG. 4 is a schematic view of the connection of the wing plate of the bow to the three-axis electromagnetic detection sensor, wherein (a) is a front view and (b) is an isometric view;

FIG. 5 is a schematic view of the mounting and fixing of a three-axis electromagnetic detection sensor;

FIG. 6 is a schematic view of a positioning/mounting bracket for a three-axis electromagnetic probe sensor, wherein (a) is a front view and (b) is an isometric view;

FIG. 7 is a schematic view of a mounting bracket for a three-axis electromagnetic detection sensor;

FIG. 8 is a schematic view of a movable cartridge of a three-axis electromagnetic detection sensor;

fig. 9 is a schematic diagram of results of electromagnetic detection tests of the submarine cable of the autonomous underwater robot, wherein Ch1(mV) is a submarine cable power-on signal characteristic, and Ch1(nT) -Ch 6(nT) are 6 induced electromagnetic signal characteristics detected by two three-axis electromagnetic detection sensors.

The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:

1-three-axis electromagnetic detection sensor, 2, 3-positioning/mounting bracket, 4-fixed bracket, 5-movable cartridge, 6-long bow wing plate, 7-bow control rudder plate, 8-sensor three-axis identification buckle and 9-mounting bayonet.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

As shown in fig. 1, the autonomous underwater robot general model for electromagnetic exploration of submarine cables is designed for the present invention. The robot adopts a driving control form of a single propeller, a stern cross rudder and a bow elevator.

Two sets of three-axis electromagnetic detection sensors are symmetrically arranged on the outer side of a long wing plate of a robot bow. Each set of three-axis electromagnetic detection sensor comprises X, Y, Z three mutually orthogonal axes, each axis is an independent magnetic induction intensity measuring system, and can measure the magnetic induction intensity parallel to the axis, and each set of electromagnetic detection sensor can measure the magnetic induction intensity at a certain point in a space vector mode by three-axis simultaneous. Preferably, the two sets of three-axis electromagnetic detection sensors have the same model, and the technical indexes of measurement precision, measurement noise and the like are the same.

Robot appendage coordinate system X_AUV/Y_AUV/Z_AUVNo. 1 three-axis electromagnetic detection sensor coordinate system X_SEN,1/Y_SEN,1/Z_SEN,1No. 2 three-axis electromagnetic detection sensor coordinate system X_SEN,2/Y_SEN,2/Z_SEN,2Three groups of three-axis coordinates are respectively corresponding to the Y axis Y of the No. 1 three-axis electromagnetic detection sensor in parallel_SEN,1Y-axis Y of No. 2 three-axis electromagnetic detection sensor_SEN,2X for keeping coaxial No. 1 three-axis electromagnetic detection sensor_SEN,1-Y_SEN,1X of plane, No. 2 three-axis electromagnetic detection sensor_SEN,2-Y_SEN,2X of plane and robot appendage_AUV-Y_AUVThe three parts are coplanar. The inertial navigation module occupies an independent cabin section and is positioned at the center gravity position of the robot, and the three X/Y/Z axes identified by the inertial navigation module and the attached coordinate system X of the robot_AUV/Y_AUV/Z_AUVThe three axes coincide. The two sets of electromagnetic detection sensors are symmetrically arranged on two sides of the robot and fixed at the outer end of the long bow wing plate through the designed mounting bracket, and the distance between the action central points of the two sets of electromagnetic detection sensors is L (unit: m). The horizontal distance between the action center point of the inertial navigation module and the connecting line center point of the two electromagnetic detection sensors is D (unit: m), and the longitude and latitude of the robot are N_AUV，E_AUV) Heading Ψ (unit: degree), roll and pitch attitude angles are respectively(unit: degree) and θ (unit: degree). The heading, roll and pitch angles of the electromagnetic detecting sensor are psi,And theta. The result of the submarine cable positioning is generally the position of the center point relative to the connecting line of the two sensors, thus converting the longitude and latitude of the robot body to the longitude and latitude of the center point of the two sensors (N)_mid，E_mid) Namely:

(N_mid，E_mid)＝(N_AUV+D cosθcosΨ，E_AUV+D cosθsinΨ)

the converted longitude and latitude coordinates of the submarine cable can be directly positioned through the converted central longitude and latitude of the double-triaxial electromagnetic detection sensor.

The robot watertight cabin section is made of aluminum alloy, the inner surface and the outer surface of the cabin section are subjected to oxidation treatment, and metal plating is processed inside the watertight cabin section. Because the electric equipment and the power supply line in the robot watertight compartment only radiate low-frequency electromagnetic fields, the heterogeneous metal plating layer and the metal shell can shield most of the electromagnetic waves radiated in the compartment, and the electromagnetic leakage generated by the sealing ring gaps between the sections of the robot watertight compartment and the tiny holes on the watertight compartment body can be basically ignored.

The robot energy battery adopts a lithium battery pack, and the energy battery cabin section is a watertight cabin section and is positioned at the stern of the robot. The energy battery pack is one of main electromagnetic field radiation sources of the robot, and the stern section of the energy battery pack is arranged to be away from the electromagnetic detection sensor at the bow part, so that the interference to the electromagnetic detection sensor in the process of inducing the submarine cable to radiate the magnetic field is reduced. In addition, the energy battery pack adopts an active electromagnetic shielding design, and the outer side of the battery pack is respectively coated with multiple layers of pig iron with high magnetic conductivity and brass with high electric conductivity from inside to outside, so that the reflection effect of the battery radiation electromagnetic waves is enhanced, the eddy current effect is increased, and the magnetic flux leakage is reduced as much as possible.

The robot propeller takes the form of an external drive, i.e. without mounting the drive inside the propeller watertight housing, the drive of the propulsion motor is built inside the robot watertight cabin and an active electromagnetic shielding design is used. The outer layer is coated by utilizing multiple layers of pig iron with high magnetic conductivity and brass with high electric conductivity, and the multiple layers of active electromagnetic shielding materials in the watertight cabin section are added, so that the active shielding effect on the driver is better. In addition, the outer layer of the propulsion motor is coated by iron foil paper, and the shell of the propulsion motor body is a watertight metal shell, so that magnetic leakage can be greatly prevented.

Fig. 2 shows a communication topology diagram of an electromagnetic detection system carried by the submarine cable electromagnetic detection autonomous underwater robot according to the present invention. The electromagnetic detection system comprises 2 sets of isomorphic electromagnetic detection sensors, a set of watertight collection host, a set of combined navigation system (comprising an inertial navigation module, a Doppler log, a Beidou/GPS, an altimeter and a depth meter), a set of navigation/electromagnetic detection synchronous controller and a set of magnetic detection node controller. The navigation/electromagnetic detection synchronous controller, the magnetic detection node controller and the inertial navigation module are installed inside a watertight cabin section of the robot, the Beidou/GPS antenna and the depth meter are used for watertight cabin penetrating installation, and the Doppler log, the altimeter, the electromagnetic detection sensor and the watertight collection host are installed on a non-watertight cabin section of the bow.

The watertight collection host mainly finishes collection, signal amplification and synchronization of electromagnetic signals of the electromagnetic detection sensors, and is in a double-input single-output form, the double-input mode means that the signals of the two sets of electromagnetic detection sensors are collected and input into the collection host in a watertight shielding cable form, and the collection host is output to a watertight cabin section of the robot in the watertight shielding cable form so as to be used for positioning and resolving of sea cables.

As shown in figure 3, the body of the watertight collection host is in a watertight form and is arranged in a non-watertight cabin section where the long bow wing is located, so that the length of a watertight transmission cable can be reduced, and the interference of electromagnetic fields radiated by complex electric equipment and power supply circuits in a sealed cabin of the robot on the collection of electromagnetic signals of the collection host is reduced.

The navigation/electromagnetic detection synchronous controller is used for synchronizing the timestamps of the watertight acquisition host, the inertial navigation system, the altimeter and the depth meter multi-channel equipment, and ensures the synchronism of acquired data so as to improve the detection and positioning precision of submarine cables. Specifically, the navigation/electromagnetic detection synchronous controller is used for synchronizing data output of four devices/systems including the watertight acquisition host, the inertial navigation system, the altimeter and the depth meter, maintaining time consistency of data output of the connection devices, and ensuring that corresponding timestamps of signal output of each sensor device are synchronous when the magnetic detection node controller carries out data processing and data storage, namely ensuring time and space consistency of each sensing device/system. The accurate positioning of the submarine cable depends on data output of four mutually independent systems/equipment, namely a watertight acquisition host, an inertial navigation system, an altimeter and a depth meter, the autonomous underwater robot needs to perform dynamic electromagnetic detection and positioning on the submarine cable in the cruising process, and if the data of each system/equipment is not time-synchronized, the corresponding moments of the acquired data fed back by each system/equipment are inconsistent, so that information such as electromagnetic signals for submarine cable positioning and resolving, the absolute position of the robot, the height, the depth and the like do not correspond to the same moment and position, and the accuracy of the submarine cable electromagnetic positioning is reduced. Therefore, the navigation/electromagnetic detection synchronous controller can ensure that the acquired data of each device/system for submarine cable space positioning calculation come from the same time, so as to improve the accuracy and precision of submarine cable space positioning. The robot obtains time information and establishes a time reference by receiving radio signals sent by a GPS satellite or a Beidou satellite when the robot is on the water surface; after the robot submerges, a high-precision time frequency standard is provided through a timing system such as a rubidium atom oscillator and the like in the controller, and the controller is enabled to have self-timing capability.

The magnetic detection node controller is used for collecting and receiving feedback signals of each sensor or subsystem, carrying out preprocessing such as filtering and fusion of original signals, carrying out time-frequency change on electromagnetic detection signals, storing data and operating a positioning algorithm of submarine cables.

Fig. 3 shows three views of a non-watertight cabin section of a bow of the autonomous underwater robot for electromagnetic detection of submarine cables according to the present invention. The relative installation positions of the watertight acquisition host, the altimeter, the Doppler log and the electromagnetic detection sensor on the cabin section are shown. Wherein the altimeter is arranged at the action center O of the two electromagnetic detection sensors₁、O₂The midpoint position of (a). The position of the submarine cable detected by the double triaxial electromagnetic detection sensor is the relative position relative to the midpoint, so that the installation position of the altimeter can detect the vertical distance of the same point from the surface of the seabed, and the burying/suspending/seabed bare leakage state of the submarine cable can be determined.

Fig. 4 shows the structural design of the long bow wing of the submarine cable electromagnetic detection autonomous underwater robot in the invention. The general assembly effect of the three-axis electromagnetic detection sensor and the mounting bracket thereof is shown in fig. 5. The movable plug-in component 5 can stretch out and draw back between the three-axis electromagnetic detection sensor 1 and the fixed support 4 after final assembly, and when the movable plug-in component is final assembled with the long bow wing plate 6, the movable plug-in component 5 is pulled out from the hole sites of the fixed support 4 and is matched with the corresponding hole sites on the long bow wing plate 6 in a plug-in manner. As shown in fig. 5 and 6, the two positioning/mounting brackets 2 and 3 have the same structure, and the mounting bayonet on the positioning/mounting bracket 3 is matched with the three-axis identification buckle on the head of the three-axis electromagnetic detection sensor 1, so that the Y axes of the two three-axis electromagnetic sensors are coaxial, and the two X-Y planes are coincident with the X-Y plane under the coordinates of the robot appendage. The structural design of the fixed bracket 4 is shown in fig. 7, and the structural design of the movable cartridge 5 is shown in fig. 8. All parts shown in fig. 4 are processed by adopting high-strength resin materials, so that the electromagnetic detection sensor is far away from the electromagnetic radiation source of the robot, and no ferromagnetic part exists around the electromagnetic detection sensor.

Preferably, the invention performs an electromagnetic isolation design on the overall level of the robot shape, the cabin section, the drive and the like, and performs an electromagnetic shielding design on the level of the system and key components such as the battery pack, the propeller, the sensor carrying device and the like, specifically:

the driving form is as follows: the robot adopts a single stern thruster form, the thrust requirement of the robot for low-speed detection and cruising is met, and the electromagnetic radiation generated by a plurality of thrusters is reduced;

cabin section configuration: the conventional design is that the battery pack is arranged at the center gravity position of the robot. Because the energy battery pack is the largest electromagnetic radiation source of the robot, the energy battery pack is arranged at the stern of the watertight cabin section of the robot, the length ratio of the bow of the robot to the nonwatertight cabin section of the stern is reasonably optimized, and the installation position of a sensor of the nonwatertight cabin section is reasonably configured, so that the gravity center and the floating center of the robot are basically in the same axis;

electromagnetic shielding of watertight sections: the metal cabin section is made of aluminum alloy, the inner wall of the watertight cabin section is subjected to metal coating processing, and as the electromagnetic radiation field inside the robot is mostly a low-frequency magnetic field, the influence of a sealing ring gap between the watertight cabin sections, a tiny hole on the watertight cabin section and the like on electromagnetic leakage is small;

carrying mode of long bow wing plate at bow part: by utilizing the characteristic that electromagnetic signals are quickly attenuated in water, an electromagnetic detection sensor carrying mode adopting a long bow wing plate is designed, so that the electromagnetic detection sensor is far away from main electromagnetic radiation sources such as an energy battery cabin section and a propeller on the spatial position as far as possible;

design of the sensor mounting bracket: all parts on the long bow wing, such as the electromagnetic detection sensor carrying and mounting bracket, the long bow wing plate, the bow control rudder plate, the rudder shaft, the bearing, the wing plate reinforcing rib and the like, are processed by adopting non-metallic materials or non-metallic standard parts are selected, so that the interference of a secondary magnetic field generated by a metal part near the electromagnetic detection sensor on a submarine cable radiation electromagnetic field is reduced;

active electromagnetic shielding of the battery: the robot energy battery is in a lithium battery pack form, pig iron with high magnetic conductivity and brass with high electric conductivity are coated on the outer side of the battery pack from inside to outside, and low-frequency electromagnetic waves of the battery pack are reduced from radiating outwards by adopting a plurality of layers of electromagnetic shielding materials;

active electromagnetic shielding of the propeller: the main electromagnetic radiation source of the propeller is a driver, the driver is externally arranged, namely, the driver of the propulsion motor is positioned in the watertight cabin, the outer layer of the driver body is coated with pig iron with high magnetic conductivity and brass with high electric conductivity from inside to outside, and the driver is provided with a plurality of layers of active electromagnetic shielding materials in the watertight cabin, so that the driver has a better active shielding effect; in addition, the outer layer of the propulsion motor is coated by iron foil paper, and the shell of the propeller body is a watertight metal shell, so that electromagnetic leakage can be effectively reduced.

As shown in fig. 9, Ch1(mV) is an electromagnetic signal characteristic of the submarine cable when the submarine cable is powered on, and Ch1(nT) -Ch 6(nT) are 6 electromagnetic signal characteristics detected by the dual-triaxial electromagnetic detection sensor, which are the test results of the submarine cable electromagnetic detection test performed by the autonomous underwater robot according to the preferred embodiment of the present invention. The diameter of a submarine cable used in the test process is about 1.8cm, the submarine cable is buried at about 3m, and the distance between the autonomous underwater robot and the submarine cable is about 20 m. It can be seen that each detection axis of each electromagnetic detection sensor accurately detects a 30Hz electromagnetic signal characteristic radiated by the submarine cable. Therefore, the autonomous underwater robot equipment developed by the invention can accurately detect the submarine cable with the diameter less than or equal to 4cm and the burying depth more than or equal to 2m, and can meet the detection requirement of an actual submarine cable system.

The embodiment only provides a preferred embodiment of the optimized submarine cable electromagnetic detection autonomous underwater robot overall equipment, and in other embodiments, developers can improve or simplify the overall equipment on the basis of the preferred embodiment, for example, the robot can adopt different profile lines, the long wing plate of the bow can be simplified into structures such as a long cylindrical rod and the like, and different mounting and positioning brackets can be designed according to different sensor structures.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.