Underwater gravity dynamic measurement system and method

Abstract

The invention relates to an underwater gravity dynamic measurement system and method, and relates to the technical field of ocean geophysics. Comprising an underwater navigation device and a gravity measurement device. The gravity measuring device is arranged on the underwater navigation device, and the gravity measuring device is used for carrying out underwater gravity measurement. The gravity measuring device comprises a pressure container, a gravimeter and a controller, the pressure container is arranged on the underwater navigation device, and a first accommodating space is formed in the pressure container; the controller is arranged in the first containing space, and the gravimeter is electrically connected with the controller. The gravity detection device is installed on an underwater navigation device, gravity measurement can be carried out on the seabed or near the bottom closer to a source body, attenuation of high-frequency components can be avoided, a gravity signal with higher strength can be obtained, small gravity abnormity cannot be sensed for traditional sea surface gravity measurement, and the measurement accuracy is improved. The problem that the resolution ratio and the observation range of an existing gravity measurement system are limited is solved.

Description

Technical Field

[0001] The present invention relates to the field of marine geophysical technology, and in particular to an underwater gravity dynamic measurement system and method. Background Art

[0002] Sea surface gravity measurements are effective for large-scale seafloor resources such as oil fields. However, the scale of seafloor mineral deposits is usually much smaller than that of oil fields. Since gravity changes inversely with the square of the distance, high-resolution gravity measurements above the seafloor are essential for exploring seafloor sediments.

[0003] However, the shipborne gravity measurement technology currently widely used has certain limitations. The intensity of the gravity signal propagates to the sea surface according to a certain attenuation law. This attenuation is related to the observation distance and the wavelength of each harmonic component of the gravity signal. As the ocean depth increases, the high-frequency components in the seabed gravity signal will decay rapidly and disappear first. The sensitivity limit of the current shipborne gravimeter cannot reach this level. The data collected by the ship's gravimeter does not have sufficient resolution for the investigation of seabed sediments. Although the seabed gravimeter used for stationary environment observation has sufficient resolution, it is difficult to observe multiple points in a short time.

[0004] Regarding the above-mentioned related technologies, there is a problem that the resolution and observation range of the existing gravity measurement system are limited. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide an underwater gravity dynamic measurement system and method, aiming to solve the problem of limitations in the resolution and observation range of the existing gravity measurement systems.

[0006] The present application provides an underwater gravity dynamic measurement system and method using the following technical solutions: An underwater gravity dynamic measurement system, comprising:

[0007] Underwater navigation devices, used for navigation underwater;

[0008] A gravity measuring device, arranged on the underwater navigation device, and used for performing underwater gravity measurement;

[0009] The gravity measuring device comprises:

[0010] A pressure container, arranged on the underwater navigation device, wherein a first accommodation space is formed in the pressure container;

[0011] A gravimeter, disposed in the first accommodation space, and used for underwater gravity measurement;

[0012] A controller is arranged in the first accommodating space, and the gravimeter is electrically connected to the controller.

[0013] Optionally, the gravimeter comprises:

[0014] A shielding shell, wherein the shielding shell is arranged in the first accommodating space, and a shielding space is formed in the shielding shell;

[0015] A gravity detection component is arranged in the shielding space, and the gravity detection component is electrically connected to the controller;

[0016] Wherein, the shielding shell is used for magnetic shielding.

[0017] Optionally, the gravimeter comprises:

[0018] A heat-insulating container is arranged in the shielding space, a heat-insulating space is formed in the heat-insulating container, and the gravity detection component is arranged in the heat-insulating space;

[0019] A temperature regulating component is arranged in the heat-insulating space, and the temperature regulating component is used to regulate the temperature in the heat-insulating space.

[0020] Optionally, the underwater gravity dynamic measurement system includes a gravity leveling system, the gravity leveling system is arranged in the first accommodating space, the gravimeter is arranged on the gravity leveling system, and the gravity leveling system is used to keep the gravimeter perpendicular to the ground.

[0021] Optionally, the gravity leveling system includes:

[0022] A first leveling frame is rotatably disposed in the pressure container, a first leveling hole is formed on the first leveling frame, and a rotation path of the first leveling frame is a first rotation path;

[0023] A second leveling frame is located in the first leveling hole, the second leveling frame is rotatably arranged in the first leveling frame, and a rotation path of the second leveling frame is a second rotation path;

[0024] A rotation angle is formed between the first rotation path and the second rotation path, and the rotation angle is greater than 0 degrees and less than 180 degrees;

[0025] The gravimeter is arranged on the second leveling frame.

[0026] Optionally, the gravity leveling system includes:

[0027] a first rotation driving member, disposed in the pressure vessel, wherein a driving end of the first rotation driving member is connected to the first leveling frame, and the first rotation driving member is used to drive the first leveling frame to rotate along the first rotation path;

[0028] a second rotation driving member, disposed on the first leveling frame, wherein a driving end of the second rotation driving member is connected to the second leveling frame, and the second rotation driving member is used to drive the second leveling frame to rotate along the second rotation path;

[0029] A rotation control member, electrically connected to the first rotation drive member and the second rotation drive member, respectively, and the rotation control member is used to control the first rotation drive member and the second rotation drive member to start or stop;

[0030] An angle monitoring component is arranged on the second leveling frame, and is used for collecting the tilt angle of the gravimeter and transmitting it to the rotation control component.

[0031] Optionally, the gravity measuring device includes an accelerometer, which is arranged on the gravity leveling system, and is used to detect the acceleration value of the underwater gravity dynamic detection system, and the accelerometer is electrically connected to the controller.

[0032] Optionally, the gravity measuring device includes a frequency meter, which is disposed in the first accommodating space and is electrically connected to the controller, and is used to provide a time reference for data synchronization of gravity data.

[0033] Optionally, the gravity measuring device includes a pressure gauge, which is disposed in the pressure vessel and electrically connected to the controller, and is used to detect the depth of the current position of the underwater gravity dynamic measurement system.

[0034] An underwater gravity dynamic measurement method, applied to an underwater gravity dynamic measurement system as described in any one of the above, the method comprising:

[0035] operating the underwater navigation device to the survey area;

[0036] Conducting underwater gravity measurement on the survey area to obtain gravity data;

[0037] The gravity data is corrected to obtain gravity acceleration.

[0038] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0039] The underwater navigation device can carry the gravity measuring device and navigate underwater in the survey area, so that the gravimeter can perform gravity measurement at the seabed or near the bottom closer to the source body. The controller can obtain the gravity data collected by the gravimeter, which can not only avoid the attenuation of high-frequency components, but also obtain higher-intensity gravity signals. Traditional sea surface gravity measurements are not sensitive to such small gravity anomalies, which solves the problem of limitations in resolution and observation range of existing gravity measurement systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 It is a schematic diagram of the installation of the underwater gravity dynamic measurement system in the embodiment of the present application;

[0042] Figure 2 It is a schematic diagram of the installation of the gravity measuring device and the mounting frame of the underwater gravity dynamic measurement system in the embodiment of the present application;

[0043] Figure 3 It is a structural schematic diagram of a gravity measuring device of an underwater gravity dynamic measurement system in an embodiment of the present application;

[0044] Figure 4 It is a schematic diagram of the internal structure of the gravity measuring device of the underwater gravity dynamic measurement system in the embodiment of the present application;

[0045] Figure 5 It is a schematic diagram of the internal structure of the gravity measuring device of the underwater gravity dynamic measurement system in the embodiment of the present application;

[0046] Figure 6 Schematic diagram of the internal structure of the gravimeter of the underwater gravity dynamic measurement system in the embodiment of the present application;

[0047] Figure 7 It is a block diagram of the electrical function principle of the underwater gravity dynamic measurement system in the embodiment of the present application;

[0048] Figure 8 It is a flow chart of the underwater gravity dynamic measurement method in an embodiment of the present application.

[0049] Description of reference numerals:

[0050] 1. Underwater navigation device; 2. Gravity measuring device; 201. Pressure vessel; 2011. Support ring; 202. Gravity meter; 2021. Shielding shell; 2022. Gravity detection component; 2022a. Mass block; 2022b. Zero length spring; 2022c. Permanent magnet; 2022d. Coil; 2022e. Capacitive sensor; 2022f. Tungsten wire; 2022g. Tension spring; 2023. Protective shell; 203, controller; 2031, control unit; 2032, storage unit; 204, gravity leveling system; 2041, first leveling frame; 2042, second leveling frame; 2043, first rotating drive member; 2044, second rotating drive member; 2045, angle monitoring member; 205, accelerometer; 206, frequency meter; 207, pressure gauge; 208, second thermometer; 209, odometer; 3, mounting bracket. DETAILED DESCRIPTION

[0051] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] The present application is further described in detail below in conjunction with the accompanying drawings.

[0053] The embodiments of the present application disclose an underwater gravity dynamic measurement system and method.

[0054] like Figure 1 As shown, an underwater gravity dynamic measurement system comprises an underwater navigation device 1 and a gravity measurement device 2. The underwater navigation device 1 is used for navigation underwater; the gravity measurement device 2 is arranged on the underwater navigation device 1, and the gravity measurement device 2 is used for underwater gravity measurement.

[0055] The underwater navigation device 1 is a remotely operated unmanned vehicle (ROV) or an autonomous underwater vehicle (AUV).

[0056] The speed of the underwater navigation device 1 in the water has a high spatial density of its trajectory line. A single underwater navigation device 1 can cover more than 1 square kilometer (km 2 ) of the survey area.

[0057] The underwater navigation device 1 is used as a platform for the gravity measurement device 2. When the measurement distance is 5m, the observation resolution can reach about 1 milligal (mGal) wavelength per 100 meters (m); on the sea surface, assuming a distance of 2000 meters (m), the peak value of the gravity anomaly will be less than 0.01mGal. Traditional sea surface gravity measurement is not sensitive to such small gravity anomalies, but these tiny gravity changes can be observed on the seabed or near the bottom.

[0058] By installing the gravity detection device on the underwater navigation device 1, gravity measurement can be carried out on the seabed or near the bottom closer to the source body, which can not only avoid the attenuation of high-frequency components, but also obtain higher-intensity gravity signals. Traditional sea surface gravity measurements are not sensitive to such small gravity anomalies, which solves the problem of limitations in resolution and observation range of existing gravity measurement systems.

[0059] like Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 7 As shown, the gravity measuring device 2 includes a pressure container 201, a gravimeter 202 and a controller 203. The pressure container 201 is arranged on the underwater navigation device 1, and a first accommodation space is formed in the pressure container 201; the gravimeter 202 is arranged in the first accommodation space, and the gravimeter 202 is used to perform underwater gravity measurement and collect gravity data; the controller 203 is arranged in the first accommodation space, and the gravimeter 202 is electrically connected to the controller 203, and the controller 203 is used to receive the gravity data.

[0060] Specifically, the underwater gravity dynamic measurement system comprises a mounting frame 3. The mounting frame 3 has an installation space formed therein.

[0061] The pressure vessel 201 is rectangular in shape and is a titanium alloy pressure vessel. The pressure vessel 201 is filled with pressurized gas and can be used normally at 2000 meters (m) below sea level. The pressure vessel 201 can prevent changes in external pressure from affecting the data collection of the gravimeter 202 in the first accommodation space.

[0062] The pressure container 201 is arranged in the installation space. The pressure container 201 is detachably connected to the mounting frame 3, and the mounting frame 3 is detachably connected to the underwater navigation device 1. In this embodiment, the pressure container 201 and the mounting frame 3, as well as the mounting frame 3 and the underwater navigation device 1 are all screwed.

[0063] Support rings 2011 are respectively provided on the side walls of both sides of the pressure vessel 201. The support rings 2011 can be provided to fix the pressure vessel 201 on the mounting frame 3 by threading ropes, thereby enhancing the installation stability of the pressure vessel 201. On the other hand, the pressure vessel 201 can be conveniently removed from the mounting frame 3 by threading ropes.

[0064] like Figure 5 and Figure 6 As shown, the gravimeter 202 includes a shielding shell 2021 and a gravity detection component 2022; the shielding shell 2021 is arranged in the first accommodating space, and a shielding space is formed in the shielding shell 2021; the gravity detection component 2022 is arranged in the shielding space, and the gravity detection component 2022 is electrically connected to the controller 203; wherein, the shielding shell 2021 is used for magnetic shielding and heat insulation.

[0065] Specifically, the gravity detection component 2022 is sensitive to the magnetic field, and the provision of the shielding shell 2021 can reduce the impact of changes in the environmental magnetic field.

[0066] In this embodiment, the shielding shell 2021 is made of Permalloy, which can not only reduce the change of the environmental magnetic field and realize the magnetic shielding in the shielding space, but also has high temperature resistance and heat insulation function.

[0067] Furthermore, the gravimeter 202 includes a protective shell 2023 , which is disposed in the first accommodation space, a second accommodation space is formed in the shell, and the shielding shell 2021 is disposed in the second accommodation space. The protective shell 2023 is used to protect the shielding shell 2021 and the gravity detection component 2022 .

[0068] Furthermore, the gravimeter 202 further includes an insulating container and a temperature adjustment component. The insulating container is arranged in the shielded space, and an insulating space is formed in the insulating container. The gravity detection component 2022 is arranged in the insulating space. The insulating container is used to ensure that the gravity detection component 2022 is not affected by sudden temperature changes. The temperature adjustment component is arranged in the insulating space, and the temperature adjustment component is used to adjust the temperature in the insulating space.

[0069] In this embodiment, the protective housing 2023, the shielding housing 2021 and the heat-insulating container are cylindrical in shape as a whole. The heat-insulating container is a Dewar container, and the temperature regulating component includes a heating net and a cooling system. The heating net is laid on the inner wall of the heat-insulating container, and the heating net is used to heat the heat-insulating space to keep the gravity detection component 2022 working at a constant temperature.

[0070] The cooling system is arranged in the heat-insulating space, and the cooling system can cool down the accommodation space.

[0071] When the outside temperature is high, the temperature of the gravimeter 202 cannot be controlled, so the gravity measuring device 2 includes a cooling system. The cooling system can be used to keep the gravimeter 202 at a constant temperature even in a high temperature environment.

[0072] The temperature adjustment component also includes a first thermometer, which is arranged in the heat-insulating space, and the first thermometer, the cooling system and the heating network are all electrically connected to the controller 203. The controller 203 can control the cooling system and the heating network to adjust the temperature of the accommodation space according to the temperature detected by the first thermometer.

[0073] In this embodiment, the temperature regulating assembly maintains the insulation space at a constant level of 50 degrees Celsius (°C) with a temperature variation of less than 0.01°C, so that the temperature of the insulation space is between 49.99°C-50.01°C.

[0074] like Figure 6 As shown, the gravity detection assembly 2022 includes a mass block 2022a, a zero-length spring 2022b, a permanent magnet 2022c, a coil 2022d, a capacitive sensor 2022e, a tungsten wire 2022f and a tension spring 2022g.

[0075] Specifically, the working principle of the gravimeter 202 is that the mass-spring system based on the axisymmetric sensor consists of 6 thin tungsten wires 2022f connected to a cylindrical mass block 2022a without friction. The movement of the mass block 2022a is restricted to one degree of freedom in the vertical direction. Therefore, the horizontal acceleration does not affect the movement and is not affected by any cross-coupling errors.

[0076] The frictionless connection of the mass block 2022a is achieved by the tension of the vertical elastic mass system. Starting from the outer frame, six horizontal tungsten wires 2022f in two planes perpendicular to the mass axis are tangentially fixed to the cylindrical mass block 2022a in a 120 degree configuration. These tungsten wires 2022f are tightened at an angle of 180 degrees (°) by a pair of tension springs 2022g.

[0077] The coil 2022d is located at the lower part of the mass block 2022a in the magnetic field of the two pairs of permanent magnets 2022c. The coil 2022d is wound along the mass axis, and the winding of the coil 2022d is rectangular, and its normal is perpendicular to the mass axis. The permanent magnet 2022c is made of samarium cobalt, which has very good temperature stability, high coercive force and high magnetic energy product, and a low inflection point of the demagnetization curve, generating a highly stable and uniform magnetic field.

[0078] A pair of samarium cobalt permanent magnets 2022c are installed horizontally, opposite to the axis of the mass block 2022a, and the air gap between the two permanent magnets 2022c surrounds the upper horizontal part of the coil 2022d winding. The magnetic induction is parallel to the normal of the coil 2022d. Another pair of magnets is installed at the lower part of the coil 2022d winding, on the same vertical plane as the two permanent magnets 2022c above. The magnetic induction intensities of the upper and lower pairs of permanent magnets 2022c are equal in magnitude, completely opposite in direction, and approximately uniform.

[0079] The coil 2022d fixed on the mass block 2022a is displaced in the vertical direction when subjected to gravity or vertical acceleration changes in the permanent magnetic field. Magnetic damping is generated by the change in magnetic flux of the coil 2022d caused by the mass movement. A high level of damping is achieved without the use of liquid.

[0080] The capacitive sensor 2022e is installed on the top of the mass block 2022a, and the capacitive sensor 2022e is used to detect the displacement of the mass block 2022a.

[0081] The gravimeter 202 also includes servo electronics, which include an excitation oscillator, a precision differential capacitive displacement sensor, a servo amplifier, and a feedback servo compensation circuit.

[0082] The servo electronics responds to the working signal and generates a proportional current through the coil 2022d. The electromagnetic force generated is equal to and opposite to the applied acceleration, which just balances the inertial reaction force. The disturbance acceleration superimposed in the vertical direction is suppressed by the electrical damping. At the same time, the servo electronics generates an integral current, driving the displacement of the mass block 2022a to zero and suppressing the vertical acceleration. Therefore, the current passing through the coil 2022d is an accurate measurement of the change in gravity and is also the gravity data obtained by the gravimeter 202.

[0083] like Figure 2 , Figure 4 , Figure 5 and Figure 7 As shown, the gravity measuring device 2 includes a gravity leveling system 204, which is disposed in the first accommodating space, and the gravimeter 202 is disposed on the gravity leveling system 204, and the gravity leveling system 204 is used to keep the gravimeter 202 vertical to the ground.

[0084] The gravity leveling system 204 includes a first leveling frame 2041 and a second leveling frame 2042. The first leveling frame 2041 is rotatably arranged in the pressure vessel 201, and a first leveling hole is formed on the first leveling frame 2041, and the rotation path of the first leveling frame 2041 is a first rotation path; the second leveling frame 2042 is located in the first leveling hole, and the second leveling frame 2042 is rotatably arranged in the first leveling frame 2041, and the gravimeter 202 is arranged on the second leveling frame 2042, and the rotation path of the second leveling frame 2042 is a second rotation path; a rotation angle is formed between the first rotation path and the second rotation path, and the rotation angle is greater than 0 degrees and less than 180 degrees. The gravimeter 202 is arranged on the second leveling frame 2042.

[0085] In this embodiment, a second leveling hole is formed on the second leveling frame 2042 , and the gravimeter 202 is clamped on the second leveling hole.

[0086] The gravity leveling system 204 further includes a first rotation driving member 2043, a second rotation driving member 2044, a rotation control member and an angle monitoring member 2045. The first rotation driving member 2043 is disposed in the pressure vessel 201, the driving end of the first rotation driving member 2043 is connected to the first leveling frame 2041, and the first rotation driving member 2043 is used to drive the first leveling frame 2041 to rotate along the first rotation path; the second rotation driving member 2044 is disposed on the first leveling frame 2041, the driving end of the second rotation driving member 2044 is connected to the second leveling frame 2042, and the second rotation driving member 2044 is used to drive the second leveling frame 2042 to rotate along the second rotation path. The rotation control component is electrically connected to the first rotation driving component 2043 and the second rotation driving component 2044 respectively, and the angle monitoring component 2045 is used to control the start or shut down of the first rotation driving component 2043 and the second rotation driving component 2044; the angle monitoring component 2045 is set on the second leveling frame 2042, and the angle monitoring component 2045 is used to collect the inclination angle of the gravimeter 202 and transmit it to the rotation control component.

[0087] Specifically, the first leveling frame 2041 is in a rectangular shape as a whole, the first leveling hole is in a rectangular shape similar to that of the first leveling frame 2041 , and the first leveling hole is concentrically arranged with the first leveling frame 2041 .

[0088] The shape of the second leveling frame 2042 is similar to that of the first leveling hole. The second leveling frame 2042 is arranged in the first leveling hole, and the second leveling frame 2042 is concentrically arranged with the first leveling hole. The shape of the second leveling hole is a rectangular hole similar to that of the second leveling frame 2042, and the second leveling hole is concentrically arranged with the second leveling frame 2042.

[0089] The first rotating driving member 2043 and the second rotating driving member 2044 are both torque motors. The first rotating driving member 2043 is disposed on the inner wall of the pressure container 201 , and a driving end of the first rotating driving member 2043 is disposed on the first leveling frame 2041 .

[0090] There is a gap between the second leveling frame 2042 and the first leveling hole. The second rotation driving member 2044 is disposed on the first leveling frame 2041 , and a driving end of the second rotation driving member 2044 is disposed on the second leveling frame 2042 .

[0091] The axial direction of the rotation axis of the first rotation driving member 2043 is the X direction, and the axial direction of the rotation axis of the second rotation driving member 2044 is the Y direction, and the X direction is perpendicular to the Y direction. That is, the rotation axis of the first rotation driving member 2043 is perpendicular to the rotation axis of the second rotation driving member 2044.

[0092] The angle monitoring component 2045 is a fiber optic gyroscope, which includes an X-axis fiber optic gyroscope and a Y-axis fiber optic gyroscope. The X-axis fiber optic gyroscope is set in the X direction and is used to measure the rotation angle and angular velocity data of the first leveling frame 2041; the Y-axis fiber optic gyroscope is used to measure the rotation angle and angular velocity data of the second leveling frame 2042.

[0093] The X-axis fiber optic gyroscope and the Y-axis fiber optic gyroscope can measure the rotation angle and angular velocity data of the first leveling frame 2041 and the second leveling frame 2042 respectively.

[0094] The rotation control member is a servo driver, which is composed of two identical channels and a digital signal processing (DSP) controller 203. The rotation control member is electrically connected or communicatively connected to the angle monitoring member 2045, the first rotation driving member 2043, and the second rotation driving member 2044. The servo driver can receive the rotation data of the first leveling frame 2041 and the second leveling frame 2042 measured by the angle monitoring member 2045 (the rotation data includes the angle and angular velocity data of the first leveling frame 2041 rotating relative to the horizontal plane and the angle and angular velocity data of the second leveling frame 2042 rotating relative to the horizontal plane), so that the servo driver controls the first rotation driving member 2043 and the second rotation driving member 2044 to level the first leveling frame 2041 and the second leveling frame 2042 according to the rotation data.

[0095] The specific working principle is that when the gravity leveling system 204 is subjected to a disturbance torque along the axial direction (the disturbance torque refers to the external torque acting on the underwater gravity dynamic measurement system, which will cause the underwater gravity dynamic measurement system to produce forced vibration. The disturbance torque is caused by various factors, such as external forces such as wind, waves, water flow, and friction torque inside the system, etc.), it will cause the first leveling frame 2041 and the second leveling frame 2042 to rotate, and the angle monitoring component 2045 installed on the second leveling frame 2042 becomes sensitive to the rotation of the angle of the first leveling frame 2041 and the second leveling frame 2042, and uploads the rotation data to the servo driver. After the signal processing of the servo driver, the control signal is sent to the first rotating drive component 2043 and the second rotating drive component 2044 respectively. After receiving the control signal, the first rotating drive component 2043 and the second rotating drive component 2044 respectively drive the first leveling frame 2041 and the second leveling frame 2042 to rotate. When the unloading torque generated by the first rotating driving member 2043 and the second rotating driving member 2044 is equal to the disturbance torque experienced by the first leveling frame 2041 and the second leveling frame 2042, the disturbance torque is completely offset, and the first leveling frame 2041 and the second leveling frame 2042 are stabilized again in a state horizontal to the ground, so that the gravimeter 202 remains perpendicular to the ground.

[0096] Furthermore, the rotation angle range of the first leveling frame 2041 and the second leveling frame 2042 is greater than or equal to -25 degrees and less than or equal to 25 degrees. To prevent the first leveling frame 2041 and the second leveling frame 2042 from rotating at a large angle so that the rotation angle exceeds the rotation angle range, the gravity leveling system 204 also includes a limiter.

[0097] In one implementation of the embodiment of the present application, a plurality of limit members are provided, and the plurality of limit members are respectively provided on the first rotation path of the first leveling frame 2041 and the second rotation path of the second leveling frame 2042 , thereby limiting the rotation angles of the first leveling frame 2041 and the second leveling frame 2042 .

[0098] In another implementation of the embodiment of the present application, the limit member includes a first limit member and a second limit member, both of which are electrically or communicatively connected to the rotation control member, and the first limit member and the second limit member are respectively arranged on the conductive circuits of the first rotation driving member 2043 and the second rotation driving member 2044, the first limit member is used to limit the rotation of the first rotation driving member 2043, and the second limit member is used to limit the rotation of the second rotation driving member 2044.

[0099] When the rotation angle of the first leveling frame 2041 or the second leveling frame 2042 is less than -25 degrees or greater than 25 degrees, the potentiometer of the first limit member or the second limit member will be triggered to cut off the power supply of the first rotating drive member 2043 or the second rotating drive member 2044, so that the first rotating drive member 2043 and the second rotating drive member 2044 maintain the current rotation angle position, so as to protect the gravimeter 202 and the gravity leveling system 204.

[0100] Furthermore, in order to minimize the magnetic field, the first rotating driving member 2043 and the second rotating driving member 2044 are covered with a magnetic shielding layer, wherein the material of the magnetic shielding layer is Permalloy.

[0101] like Figure 2 , Figure 5 and Figure 7 As shown, the gravity measuring device 2 includes an accelerometer 205 , which is disposed on the gravity leveling system 204 . The accelerometer 205 is used to detect the acceleration value of the underwater gravity dynamic detection system, and the accelerometer 205 is electrically connected to the controller 203 .

[0102] Specifically, the direction perpendicular to the ground is assumed to be the Z direction.

[0103] The accelerometer 205 includes a first accelerometer, a second accelerometer, and a third accelerometer, and the first accelerometer, the second accelerometer, and the third accelerometer are respectively disposed on the second leveling frame 2042 .

[0104] The first accelerometer, the second accelerometer and the third accelerometer are respectively used to detect the acceleration of the underwater gravity dynamic measurement system in the X direction, the Y direction and the Z direction during the movement, wherein the acceleration recorded in the Z direction is the vertical acceleration, and the accelerations recorded in the X direction and the Y direction are both non-vertical accelerations.

[0105] The first accelerometer, the second accelerometer and the third accelerometer are electrically connected to the controller 203 respectively, and the acceleration values ​​detected by the first accelerometer, the second accelerometer and the third accelerometer can be uploaded to the controller 203 for signal processing.

[0106] The configuration of the accelerometer 205 has the following advantages:

[0107] 1. The accelerometer 205 can be used for horizontal calibration.

[0108] Since the first leveling frame 2041 and the second leveling frame 2042 may not be horizontal initially or the angle monitoring component 2045 may drift or the earth rotates. In order to keep the height of the second leveling frame 2042 and the first leveling frame 2041 horizontal, the non-vertical acceleration values ​​detected by the first accelerometer and the second accelerometer can be used as horizontal marks, and the controller 203 is pre-set with a horizontal signal value. When the non-vertical acceleration values ​​detected by the first accelerometer and the second accelerometer received by the controller 203 do not match the horizontal signal value, an error signal will be generated, and each error signal will be fed back to the angle monitoring component 2045 in the corresponding direction, and the correction will be performed step by step.

[0109] Second, the accelerometer 205 can check and filter out gravity data.

[0110] Since the underwater gravity dynamic measurement system moves and rotates in all directions, the gravity data measured by the gravimeter 202 contains not only gravity acceleration but also non-gravity acceleration. The gravimeter 202 itself cannot identify and distinguish these two accelerations, so the data of the gravimeter 202 needs to be corrected in various ways.

[0111] By setting up the accelerometer 205 for separately measuring the vertical acceleration and the non-vertical acceleration, the non-gravity acceleration value in the gravity data is finally deducted according to the detected vertical acceleration and the non-vertical acceleration in the data processing link of the controller 203.

[0112] Furthermore, since the acceleration value detected by the third accelerometer is a vertical acceleration value and not a gravity acceleration value, it is difficult to calibrate the gravity data by relying solely on the accelerometer 205. To improve the accuracy of the gravity data, the gravity detection device further includes a pressure gauge 207, which is disposed in the pressure vessel 201 and connected to the seawater through a high-pressure port. The pressure gauge 207 is electrically connected to the controller 203, and the pressure gauge 207 is used to detect the depth of the current position of the underwater gravity dynamic measurement system.

[0113] The pressure gauge 207 is a precision pressure gauge using resonant quartz technology. Its resolution is better than one millionth of the maximum measured value. The pressure gauge 207 has a digital output and a selectable sampling frequency. In this embodiment, in order to increase the sampling rate and obtain a wider signal bandwidth, a frequency of 50 Hz (hz) is selected for observation.

[0114] In order to achieve more accurate navigation, the gravity measuring device 2 further includes an odometer 209, which is disposed on the outer surface of the pressure vessel 201 and is electrically connected to the controller 203. The odometer 209 can transmit the collected data to the controller 203. In this embodiment, the odometer 209 is a Doppler velocity odometer 209.

[0115] It should be noted that, in order to protect the odometer 209 from being damaged and to increase the service life of the odometer 209, the odometer 209 can also be disposed in the pressure vessel 201 and only needs to be connected to the seawater through the high-pressure port.

[0116] The odometer 209 can measure the speed of the underwater vehicle 1 to suppress the error in the inertial system, thereby providing a more accurate position of the underwater vehicle 1 in the seawater.

[0117] The gravity measuring device 2 includes a second thermometer 208, which is disposed on the outer surface of the pressure vessel 201. The second thermometer 208 is electrically connected to the controller 203, and the second thermometer 208 can detect the water temperature at the current depth and upload it to the controller 203. It should be noted that in order to protect the second thermometer 208 from damage and to increase the service life of the second thermometer 208, the second thermometer 208 can also be disposed in the pressure vessel 201, and only needs to be connected to the seawater through the high-pressure port.

[0118] The gravity measuring device 2 includes a frequency meter 206 . The frequency meter 206 is disposed in the first accommodation space. The frequency meter 206 is electrically connected to the controller 203 . The frequency meter 206 is used to provide a time reference for data synchronization of gravity data.

[0119] Specifically, the frequency meter 206 has a resolution of 0.1 ppm within 1 second (s); the frequency meter 206 can be used to provide a time reference for data synchronization for the output data of sensors such as the gravimeter 202, the gravity leveling system 204, the odometer 209, the pressure gauge 207 and the second thermometer 208. The time reference of the frequency meter 206 can effectively integrate the data of sensors such as the gravimeter 202, the gravity leveling system 204, the odometer 209, the pressure gauge 207 and the second thermometer 208.

[0120] like Figure 1 and Figure 7 As shown, the underwater navigation device 1 is electrically connected to the gravity measuring device 2. During the observation period, the underwater navigation device 1 can regularly send the gravity data detected by the gravity measuring device 2 to the surface mother ship. At the same time, the underwater navigation device 1 is equipped with a backup UPS for emergency shutdown.

[0121] like Figure 5 and Figure 7As shown, the underwater gravity dynamic measurement system must simultaneously receive and store data from sensors such as the gravimeter 202, the gravity leveling system 204, the odometer 209, the pressure gauge 207, and the second thermometer 208. The data time is very important for the correction of gravity data. The clock and the recording system of the underwater navigation device 1 are synchronized, and when the recording system receives the data of each sensor, a timestamp is added to the data of each sensor.

[0122] The controller 203 includes a control unit 2031 and a storage unit 2032. The control unit 2031 is electrically connected to the storage unit 2032. The storage unit 2032 includes a sensor interface and a data recording unit.

[0123] The sensor interface and data logging unit are developed using a central processing unit (CPU) and a field programmable gate array (FPGA).

[0124] The data of sensors such as the gravimeter 202, the gravity leveling system 204, the odometer 209, the pressure gauge 207 and the second thermometer 208 can be recorded by the sensor interface and the data recording unit at the same time. The control unit 2031 can obtain the data of sensors such as the gravimeter 202, the gravity leveling system 204, the odometer 209, the pressure gauge 207 and the second thermometer 208 from the storage unit 2032 and process them. The processed data can be uploaded to the remote control center on the one hand, and can also control sensors such as the gravimeter 202 and the gravity leveling system 204 to perform automatic adjustments on the other hand.

[0125] The sensor interface and data logging unit are equipped with a rubidium clock, which adds a time stamp when receiving the data from each sensor.

[0126] For analog data, a timestamp is added during analog-to-digital (A / D) conversion. The rubidium clock in the sensor interface and data logging unit can be synchronized with the rubidium clock in the sensor through the communication function. The data collected by the sensor interface and data logging unit is stored in a storage device, and a plurality of storage devices are provided, each storage device has the same data as a backup of another.

[0127] In this embodiment, the storage element is an SD memory card. Two SD memory cards are provided, and each SD memory card has the same data as a backup of the other. The sensor interface and data recording unit device has an Ethernet interface, which enables the data in the SD memory card to be retrieved through the Ethernet interface without opening the pressure vessel 201. The Ethernet interface is also used for the maintenance of the sensor interface and the data recording unit.

[0128] The sensor interface and data logging unit arrangement may monitor the gravimeter 202 and gravity leveling system 204 during operation.

[0129] like Figure 8 As shown, an underwater gravity dynamic measurement method is applied to the underwater gravity dynamic measurement system as described in any one of the above items, comprising the steps of:

[0130] S100, operating the underwater navigation device 1 to the investigation area.

[0131] Specifically, the investigation area is the seabed or near the bottom close to the source body.

[0132] By installing the specially made gravimeter 202 on the underwater navigation device 1 and performing gravity measurement in the survey area, it is possible to avoid the attenuation of high-frequency components and obtain a higher-intensity gravity signal.

[0133] Due to the speed of the underwater navigation device 1 in the water, the spatial density of its trajectory is very high, and a single submersible can cover more than 1 square kilometer (km 2 ) of the survey area.

[0134] The underwater navigation device 1 is used as the bearing platform of the gravimeter 202. When the underwater gravity dynamic measurement system is 5m away from the seabed, its observation resolution can reach about 1mGal / 100m wavelength; on the sea surface, the peak value of gravity anomaly will be less than 0.01mGal. Traditional sea surface gravity measurement cannot be sensitive to such small gravity anomalies, but these tiny gravity changes can be observed on the seabed or near the bottom.

[0135] S200: Perform underwater gravity measurement on the survey area to obtain gravity data.

[0136] Specifically, gravity data includes gravitational acceleration and other accelerations.

[0137] The gravimeter 202 collects gravity data while moving with the underwater navigation device 1 .

[0138] S300, calibrating gravity data and obtaining gravity acceleration.

[0139] Specifically, while the gravimeter 202 is collecting gravity data, the odometer 209, the pressure gauge 207, the frequency meter 206, the accelerometer 205, the second thermometer 208 and other sensors will collect corresponding correction data, and the gravity data and the correction data will be stored in the storage unit 2032. Then the control unit 2031 will call the gravity data and the correction data in the storage unit 2032. After the data processing by the control unit 2031, the correction data can balance other accelerations in the gravity data, and finally obtain the gravity acceleration required for the test. The processed gravity acceleration will be uploaded to the remote control center.

[0140] When the gravimeter 202 is collecting gravity data, the gravity leveling system 204 will cooperate with the accelerometer 205 to monitor the gravimeter 202 in real time. When the non-vertical acceleration values ​​detected by the first accelerometer 205 and the second accelerometer 205 received by the controller 203 do not match the horizontal signal values, an error signal will be generated, and each error signal will be fed back to the angle monitoring component 2045 in the corresponding direction. The angle monitoring component 2045 will control the first leveling frame 2041 and the second leveling frame 2042 to adjust and gradually feed the calibration.

[0141] In summary, due to the observation distance and the attenuation effect of seawater, the existing ship-borne gravity measurements cannot observe the high-frequency gravity field information of the shallow seabed, such as oil and gas resources, natural gas hydrates, submarine volcanoes, etc., nor can they detect small-scale targets on the seabed.

[0142] The present invention integrates sensors such as a gravimeter 202, a gravity leveling system 204, a speedometer 209, and a pressure gauge 207 into a pressure vessel 201, and uses an underwater navigation device 1 to carry it, so as to dynamically observe gravity near the seabed. This can overcome the limitations of traditional surface ship-borne gravity measurement systems and observe high-resolution ocean gravity field information.

[0143] The problem of limitations in resolution and observation range of existing gravity measurement systems is solved.

[0144] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0145] It should be noted that the present invention takes an underwater dynamic gravity measurement system and method as an example to introduce the specific structure and working principle of the present invention, but the application of the present invention is not limited to an underwater dynamic gravity measurement system and method, and can also be applied to the production and use of other similar workpieces.

[0146] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0147] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An underwater gravity dynamic measurement system, characterized in that: include: Underwater navigation devices, used for navigation underwater; A gravity measuring device, arranged on the underwater navigation device, and used for performing underwater gravity measurement; The gravity measuring device comprises: A pressure container, arranged on the underwater navigation device, wherein a first accommodation space is formed in the pressure container; A gravimeter, disposed in the first accommodation space, and used for underwater gravity measurement; A controller is arranged in the first accommodating space, and the gravimeter is electrically connected to the controller.

2. The underwater gravity dynamic measurement system according to claim 1, characterized in that: The gravimeter comprises: A shielding shell, wherein the shielding shell is arranged in the first accommodating space, and a shielding space is formed in the shielding shell; A gravity detection component is arranged in the shielding space, and the gravity detection component is electrically connected to the controller; Wherein, the shielding shell is used for magnetic shielding.

3. The underwater gravity dynamic measurement system according to claim 2, characterized in that: The gravimeter comprises: A heat-insulating container is arranged in the shielding space, a heat-insulating space is formed in the heat-insulating container, and the gravity detection component is arranged in the heat-insulating space; A temperature regulating component is arranged in the heat-insulating space, and the temperature regulating component is used to regulate the temperature in the heat-insulating space.

4. The underwater gravity dynamic measurement system according to claim 1, characterized in that: The underwater gravity dynamic measurement system includes a gravity leveling system, which is arranged in the first accommodating space, and the gravimeter is arranged on the gravity leveling system, and the gravity leveling system is used to keep the gravimeter perpendicular to the ground.

5. The underwater gravity dynamic measurement system according to claim 4, characterized in that: The gravity leveling system comprises: A first leveling frame is rotatably disposed in the pressure container, a first leveling hole is formed on the first leveling frame, and a rotation path of the first leveling frame is a first rotation path; A second leveling frame is located in the first leveling hole, the second leveling frame is rotatably arranged in the first leveling frame, and a rotation path of the second leveling frame is a second rotation path; A rotation angle is formed between the first rotation path and the second rotation path, and the rotation angle is greater than 0 degrees and less than 180 degrees; The gravimeter is arranged on the second leveling frame.

6. The underwater gravity dynamic measurement system according to claim 5, characterized in that: The gravity leveling system comprises: a first rotation driving member, disposed in the pressure vessel, wherein a driving end of the first rotation driving member is connected to the first leveling frame, and the first rotation driving member is used to drive the first leveling frame to rotate along the first rotation path; a second rotation driving member, disposed on the first leveling frame, wherein a driving end of the second rotation driving member is connected to the second leveling frame, and the second rotation driving member is used to drive the second leveling frame to rotate along the second rotation path; A rotation control member, electrically connected to the first rotation drive member and the second rotation drive member, respectively, and the rotation control member is used to control the first rotation drive member and the second rotation drive member to start or stop; An angle monitoring component is arranged on the second leveling frame, and is used for collecting the tilt angle of the gravimeter and transmitting it to the rotation control component.

7. The underwater gravity dynamic measurement system according to claim 5, characterized in that: The gravity measuring device comprises an accelerometer, which is arranged on the gravity leveling system and used to detect the acceleration value of the underwater gravity dynamic detection system. The accelerometer is electrically connected to the controller.

8. The underwater gravity dynamic measurement system according to claim 1, characterized in that: The gravity measuring device comprises a frequency meter, which is arranged in the first accommodation space and is electrically connected to the controller. The frequency meter is used to provide a time reference for data synchronization of gravity data.

9. The underwater gravity dynamic measurement system according to claim 1, characterized in that: The gravity measuring device comprises a pressure gauge, which is arranged in the pressure container and electrically connected to the controller. The pressure gauge is used to detect the depth of the current position of the underwater gravity dynamic measurement system.

10. A method for underwater dynamic gravity measurement, characterized in that: Applied to the underwater gravity dynamic measurement system according to any one of claims 1 to 9, the method comprises: operating the underwater navigation device to the survey area; Underwater gravity measurement is performed on the survey area to obtain gravity data; and the gravity data is corrected to obtain gravity acceleration.

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