Leveling mechanism, gravimeter and underwater gravity dynamic measurement system

Abstract

The invention relates to the technical field of underwater gravity measurement, and discloses a leveling mechanism, a gravimeter and an underwater gravity dynamic measurement system.The leveling mechanism comprises a bearing frame, a first frame, a second frame, a first electric executing mechanism and a second electric executing mechanism, the first frame can rotate around a first axis; the second frame is movably mounted in the first frame and can rotate around a second axis, and the first axis and the second axis are orthogonal; the first electric actuating mechanism is used for adjusting the roll angle of the first frame; the second electric actuating mechanism is used for adjusting the pitch angle of the second frame. By means of the design, compared with a single-axis compensation system, pitching and rolling disturbance in the navigation process of the AUV or the ROV can be offset at the same time, so that the horizontal keeping capacity of the underwater gravity dynamic measurement system in the three-dimensional dynamic environment is improved, measurement errors caused by multi-axis attitude coupling can be reduced, and the gravity measurement precision is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the underwater gravity measurement technical field, and particularly relates to a leveling mechanism, a gravimeter and an underwater gravity dynamic measurement system. BACKGROUND

[0002] Gravity measurement is an important geophysical means for studying crustal structure, resource distribution and geological anomalies, and the measurement accuracy directly depends on the attitude stability and leveling accuracy of the instrument. In the field of marine gravity measurement, especially in the underwater environment, the measurement platform (such as AUV or ROV) is disturbed by waves, ocean currents, propulsion system vibration and other factors, and is prone to attitude changes (pitch, roll, etc.), so that the measurement reference plane of the gravimeter deviates from the horizontal, resulting in significant amplification of measurement errors. High-precision gravity observation in deep-sea cold springs, hydrothermal systems and natural gas hydrates requires the gravimeter to maintain a horizontal state in a dynamic environment. Methane aggregation, stratum collapse and fluid activity in cold spring areas often cause slight changes in the gravity field, so even a very small attitude tilt or drift can mask the target signal, resulting in distorted data or misjudgment. To achieve such precise measurement, a high-response, high-precision dynamic leveling mechanism must be relied on to offset the disturbance of platform motion to the measurement reference. Therefore, the leveling structure is one of the most critical stability controls in the underwater gravity measurement system, and its performance directly determines the accuracy and reliability of the measurement system.

[0003] At present, the leveling mechanism of the underwater gravimeter mainly has the following problems: The traditional gravimeter adopts a mechanical damping type leveling mechanism, which mainly relies on mechanical pendulums, springs or liquid dampers to balance the gravity restoring force, and has certain effect in land and static environment, but in a dynamic underwater environment, due to slow response speed, large friction resistance and complex mechanical coupling, it cannot follow the attitude change of the vehicle in real time, and when the ROV or AUV has a rapid attitude change (such as ±10° pitch), the mechanical damping type leveling mechanism usually lags for several seconds to tens of seconds, causing short-term drift of gravity measurement data and increase of low-frequency noise. SUMMARY

[0004] The main purpose of the present application is to provide a leveling mechanism, which aims to improve the shortcomings of the prior art and solve the problem that the gravimeter is easily disturbed by pitch and roll, causing short-term drift of gravity measurement data.

[0005] To achieve the above purpose, the leveling mechanism provided by the present application comprises: a bearing frame; a first frame, the first frame is movably installed in the bearing frame, and the first frame can rotate around a first axis; A second frame is movably installed within the first frame, and the second frame is rotatable about a second axis, the first axis and the second axis being orthogonal; A first electric actuator is used to adjust the roll angle of the first frame; The second electric actuator is used to adjust the pitch angle of the second frame.

[0006] Optionally, the first frame and the supporting frame are connected by a first revolute joint, the central axis of the first revolute joint coincides with the first axis, and the first revolute joint includes: First bushing; The first bearing, the first bushing, and one of the first bearings are mounted on the first frame, and the other of the first bushing and the first bearing is mounted on the bearing frame. The first bushing is inserted into the bearing hole of the first bearing.

[0007] Optionally, the first frame and the second frame are connected by a second revolute joint, the central axis of the second revolute joint coincides with the second axis, and the second revolute joint includes: Second bushing; The second bearing, the second bushing, and one of the second bearings are mounted on the first frame, and the other of the second bushing and the second bearing is mounted on the second frame. The second bushing is inserted into the bearing hole of the second bearing.

[0008] Optionally, a first linkage mechanism is provided on one side of the first frame, and the first electric actuator is installed on the side wall of the supporting frame, with the first electric actuator in contact with the first linkage mechanism.

[0009] Optionally, the first linkage mechanism includes: Two first links are mounted on the first frame; A first arc-shaped component, one end of which is connected to a first connecting rod, and the other end of which is connected to another first connecting rod; The arc-shaped opening of the first arc-shaped component faces the first electric actuator, and the first electric actuator is arranged radially along the first arc-shaped component.

[0010] Optionally, a second linkage mechanism is provided on one side of the second frame, and the second electric actuator is installed on the side wall of the first frame, with the second electric actuator and the second linkage mechanism in contact.

[0011] Optionally, the second linkage mechanism includes: Two second links are mounted on the second frame; The second arc-shaped component has one end connected to a second connecting rod and the other end connected to another second connecting rod. The arc-shaped opening of the second arc-shaped member faces the second electric actuator, and the second electric actuator is arranged radially along the second arc-shaped member.

[0012] Optionally, the bottom of the second frame is provided with a support structure, which includes a connecting plate and a support plate, and the support plate and the second frame are connected by the connecting plate.

[0013] This application also provides a gravimeter, including the above-described leveling mechanism, gravity sensor, and spherical sealed chamber, wherein the leveling mechanism is installed inside the spherical sealed chamber, and the gravity sensor is installed inside the leveling mechanism.

[0014] In addition, this application also provides an underwater gravity dynamic measurement system, including the above-mentioned gravimeter and mounting frame, wherein the gravimeter is installed in the mounting frame.

[0015] Beneficial Effects: The leveling mechanism proposed in this invention includes a support frame, a first frame, a second frame, a first electric actuator, and a second electric actuator. The first frame is movably installed within the support frame and can rotate around a first axis. The second frame is movably installed within the first frame and can rotate around a second axis, which is orthogonal to the first axis. The first electric actuator is used to adjust the roll angle of the first frame, and the second electric actuator is used to adjust the pitch angle of the second frame. Specifically, the first frame is placed within the support frame, and its roll angle is independently adjusted by the first electric actuator. The second frame is placed within the first frame, and its pitch angle is independently adjusted by the second electric actuator. This design creates a nested, decoupled arrangement between the first and second frames, forming a dual-axis inertial decoupling structure. The rotation axes of the first and second frames are orthogonal in space. Compared to a single-axis compensation system, this design can simultaneously counteract the pitch and roll disturbances during AUV or ROV navigation, thereby improving the leveling capability of the underwater gravity dynamic measurement system in a three-dimensional dynamic environment. Furthermore, it can reduce measurement errors caused by multi-axis attitude coupling and improve gravity measurement accuracy. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a structural exploded view of the leveling mechanism disclosed in this application; Figure 2 This is a three-dimensional structural diagram of the leveling mechanism disclosed in this application; Figure 3 This is a top view of the leveling mechanism disclosed in this application; Figure 4 This is one of the schematic diagrams of the internal structure of the gravimeter disclosed in this application; Figure 5 This is the second schematic diagram of the internal structure of the gravimeter disclosed in this application; Figure 6 This is a three-dimensional structural schematic diagram of the gravimeter disclosed in this application; Figure 7 This is an exploded structural diagram of the gravimeter disclosed in this application; Figure 8 This is a schematic diagram of the underwater gravity dynamic measurement system disclosed in this application. Figure 9 This is a schematic diagram of the installation of the underwater gravity dynamic measurement system and underwater vehicle disclosed in this application.

[0018] Explanation of icon numbers: 1. Support frame; 11. First mounting plate; 12. First hub slot; 13. Fan-shaped structure; 2. First frame; 21. First linkage mechanism; 211. First link; 212. First arc-shaped component; 22. First support part; 23. Second mounting plate; 24. Second hub slot; 3. Second frame; 31. Second linkage mechanism; 311. Second linkage; 312. Second arc-shaped component; 32. Lifting structure; 321. Connecting plate; 322. Support plate; 33. Second support part; 4. First electric actuator; 41. First drive motor; 42. First roller; 5. Second electric actuator; 51. Second drive motor; 52. Second roller; 6. First rotating joint; 61. First bushing; 62. First bearing; 7. Second rotating joint; 71. Second bushing; 72. Second bearing; 8. Gravity sensor; 81. Groove; 9. Spherical sealed chamber; 91. Load-bearing platform; 92. Pressure gauge; 93. Thermometer; 94. DVL speedometer; 95. AC-DC converter; 96. Storage module; 10. Install the frame; 100. Underwater vehicles.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0022] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0024] Gravity measurement is an important geophysical method for studying crustal structure, resource distribution, and geological anomalies. Its accuracy directly depends on the instrument's attitude stability and leveling precision. In marine gravity measurement, especially in underwater environments, AUVs (Autonomous Underwater Vehicles) and ROVs (Remote Operated Vehicles) are easily affected by various factors such as waves, ocean currents, and propulsion system vibrations, leading to attitude changes (pitch, roll, etc.). This causes the gravimeter's measurement reference plane to deviate from horizontal, significantly amplifying measurement errors. High-precision gravity observations in complex environments such as deep-sea cold seeps, hydrothermal systems, and natural gas hydrates require the gravimeter to maintain a horizontal position even in dynamic environments. Methane aggregation, strata collapse, and fluid activity in cold seep areas often cause subtle changes in the gravity field. Therefore, even minute attitude tilts or drifts can mask target signals, leading to data distortion or misinterpretation. To achieve such precise measurements, a high-response, high-precision dynamic leveling mechanism is essential to counteract the disturbances to the measurement reference caused by platform movement. Therefore, the leveling structure is one of the most critical stability controls in an underwater gravity measurement system, and its performance directly determines the accuracy and reliability of the measurement system.

[0025] Currently, the leveling technology for underwater gravimeters mainly suffers from the following problems: 1. Traditional gravimeters use mechanically damped leveling mechanisms, which rely mainly on mechanical pendulums, springs, or liquid damping to balance the gravity restoring force. This is effective in land and static environments, but in dynamic underwater environments, due to slow response speed, high frictional resistance, and complex mechanical coupling, it cannot keep up with the attitude changes of the ROV in real time. When the ROV or AUV undergoes rapid attitude changes (such as ±10° pitch), the mechanically damped leveling mechanism usually lags behind by several seconds to tens of seconds, causing short-term drift of gravity measurement data and an increase in low-frequency noise.

[0026] 2. Some new underwater gravity measurement devices employ a single-axis electric leveling system, using a motor or electric actuator to drive the platform in a specific direction for automatic correction. However, the attitude changes of underwater vehicles often exhibit three-dimensional coupling characteristics, and single-axis compensation alone cannot completely eliminate the combined interference of roll and pitch. When the vehicle experiences multi-axis attitude disturbances simultaneously, the gravimeter reference plane will still tilt, causing measurement errors to exceed the allowable range.

[0027] 3. In recent years, inertial navigation systems (INS) have been introduced into gravity measurement attitude control to monitor attitude angle changes and correct data. However, most systems only perform post-processing algorithmic compensation based on attitude angles, failing to achieve real-time leveling at the physical level, resulting in the accumulation of dynamic errors during measurement. Especially in deep-sea cold seep areas, where environmental pressure can reach tens of megapascals and temperature gradients are significant, traditional inertial compensation algorithms struggle to completely offset the effects of mechanical structural deformation and time-varying drift.

[0028] Based on this, this embodiment provides a leveling mechanism, see [link to relevant documentation]. Figures 1-3 As shown, the leveling mechanism includes a support frame 1, a first frame 2, a second frame 3, a first electric actuator 4, and a second electric actuator 5. The first frame 2 is movably installed inside the support frame 1 and can rotate around a first axis. The second frame 3 is movably installed inside the first frame 2 and can rotate around a second axis, which is orthogonal to the first axis. The first electric actuator 4 is used to adjust the roll angle of the first frame 2, and the second electric actuator 5 is used to adjust the pitch angle of the second frame 3.

[0029] Specifically, the first frame 2 is placed inside the supporting frame 1, and its roll angle is independently adjusted by the first electric actuator 4. The second frame 3 is placed inside the first frame 2, and its pitch angle is independently adjusted by the second electric actuator 5. The first frame 2 and the second frame 3 are arranged in a nested decoupled manner to form a dual-axis inertial decoupling structure. The rotation axis of the first frame 2 and the rotation axis of the second frame 3 are orthogonal in space. When the gravity sensor 8 is installed in the second frame 3, the installation position of the gravity sensor 8 can be adjusted so that the intersection of the rotation axis of the first frame 2 and the rotation axis of the second frame 3 coincides with the center of gravity of the gravity sensor 8, thereby achieving complete attitude decoupling at the physical level. Compared with a single-axis compensation system, it can simultaneously cancel the pitch and roll disturbances during AUV or ROV navigation, thereby improving the horizontal maintenance capability of the underwater gravity dynamic measurement system in a three-dimensional dynamic environment. Moreover, it can also reduce the measurement error caused by multi-axis attitude coupling and improve the gravity measurement accuracy.

[0030] In this embodiment, the first frame 2 and the second frame 3 are decoupled, meaning that the roll adjustment of the first frame 2 and the pitch adjustment of the second frame 3 are respectively completed by two independent electric actuators. The driving method and sensor feedback are separated from each other. When the system adjusts in the pitch direction to compensate, it will not affect the stability of the roll direction; similarly, when adjusting in the roll direction to compensate, it will not cause pitch angle error.

[0031] In one embodiment of this application, the first frame 2 and the bearing frame 1 are connected by a first rotating joint 6. The central axis of the first rotating joint 6 coincides with the first axis. The first rotating joint 6 includes a first bushing 61 and a first bearing 62. One of the first bushing 61 and the first bearing 62 is mounted on the first frame 2, and the other of the first bushing 61 and the first bearing 62 is mounted on the bearing frame 1. The first bushing 61 is inserted into the bearing hole of the first bearing 62.

[0032] Specifically, the first bearing 62 is a deep groove ball bearing, and the first frame 2 and the second frame 3 are both made by an integral molding process. The preferred material is aluminum alloy or titanium alloy. Of course, the materials used to make the first frame 2 and the second frame 3 can also be other composite materials that meet the structural strength requirements. Those skilled in the art can select the specific materials to make the first frame 2 and the second frame 3 according to actual production needs. This application does not impose too many restrictions on this.

[0033] See Figures 1-2 As shown, the first frame 2 and the second frame 3 are connected by a second rotating joint 7. The central axis of the second rotating joint 7 coincides with the second axis. The second rotating joint 7 includes a second bushing 71 and a second bearing 72. One of the second bushing 71 and the second bearing 72 is installed on the first frame 2, and the other of the second bushing 71 and the second bearing 72 is installed on the second frame 3. The second bushing 71 is inserted into the bearing hole of the second bearing 72.

[0034] Specifically, the second bearing 72 is a deep groove ball bearing.

[0035] See Figure 2 As shown, a first linkage mechanism 21 is provided on one side of the first frame 2, and a first electric actuator 4 is installed on the side wall of the supporting frame 1. The first electric actuator 4 and the first linkage mechanism 21 are in contact.

[0036] Specifically, the first linkage mechanism 21 includes two first links 211 and a first arc-shaped member 212. The two first links 211 are mounted on the first frame 2. One end of the first arc-shaped member 212 is connected to one of the first links 211, and the other end of the first arc-shaped member 212 is connected to the other first link 211. The arc-shaped opening of the first arc-shaped member 212 faces the first electric actuator 4, and the first electric actuator 4 is arranged radially along the first arc-shaped member 212.

[0037] In this embodiment, the first electric actuator 4 includes a first drive motor 41 and a first roller 42. The first drive motor 41 drives the first roller 42 to rotate, thereby causing friction between the first roller 42 and the first arc-shaped member 212 to control the roll angle of the first frame 2.

[0038] Of course, the first drive motor 41 can also be a voice coil motor, a servo motor, or a piezoelectric driver.

[0039] When the gravity sensor 8 installed in the second frame 3 is disturbed in the roll direction as the attitude of the aircraft changes, the first drive motor 41 drives the first roller 42 to rotate. Power is transmitted through the frictional coupling between the first roller 42 and the first arc-shaped member 212. The frictional action generates a corresponding compensating torque on the arc surface of the first arc-shaped member 212, thereby achieving active attitude correction to counteract the roll disturbance of the gravity sensor 8.

[0040] See Figure 2 As shown, a second linkage mechanism 31 is provided on one side of the second frame 3, and a second electric actuator 5 is installed on the side wall of the first frame 2. The second electric actuator 5 is in contact with the second linkage mechanism 31.

[0041] Specifically, the second linkage mechanism 31 includes two second linkages 311 and a second arc-shaped member 312. The two second linkages 311 are mounted on the second frame 3. One end of the second arc-shaped member 312 is connected to one of the second linkages 311, and the other end of the second arc-shaped member 312 is connected to another second linkage 311. The arc-shaped opening of the second arc-shaped member 312 faces the second electric actuator 5, and the second electric actuator 5 is arranged radially along the second arc-shaped member 312.

[0042] In this embodiment, the second electric actuator 5 includes a second drive motor 51 and a second roller 52. The second drive motor 51 drives the second roller 52 to rotate, thereby causing friction between the second roller 52 and the second arc-shaped member 312 to control the pitch angle of the second frame 3.

[0043] Of course, the second drive motor 51 can also be a voice coil motor, a servo motor, or a piezoelectric driver.

[0044] When the gravity sensor 8 installed in the second frame 3 is disturbed in the pitch direction as the attitude of the aircraft changes, the second drive motor 51 drives the second roller 52 to rotate. Power is transmitted through the frictional coupling between the second roller 52 and the second arc-shaped member 312. The frictional action generates a corresponding compensating torque on the arc surface of the second arc-shaped member 312, thereby achieving active attitude correction to counteract the pitch disturbance of the gravity sensor 8.

[0045] See Figure 1 As shown, a support structure 32 is provided at the bottom of the second frame 3. The support structure 32 includes a connecting plate 321 and a support plate 322. The support plate 322 is connected to the second frame 3 through the connecting plate 321.

[0046] See Figures 4-5As shown, the gravity sensor 8 is installed inside the second frame 3. Grooves 81 are provided on both sides of the bottom of the gravity sensor 8. When the gravity sensor 8 is placed inside the second frame 3, a portion of the support plate 322 is embedded in the groove 81 to support the gravity sensor 8 and prevent the gravity sensor 8 from falling out of the second frame 3.

[0047] See Figure 1 As shown, in this embodiment, the first frame 2 is provided with two first support parts 22, which are respectively provided at the upper and lower ends of the first frame 2. One of the two first connecting rods 211 is installed on one first support part 22, and the other of the two first connecting rods 211 is installed on the other first support part 22.

[0048] The second frame 3 is provided with two second support parts 33, which are respectively located at the upper and lower ends of the second frame 3. One of the two second connecting rods 311 is installed on one second support part 33, and the other of the two second connecting rods 311 is installed on the other second support part 33.

[0049] See Figures 1-2 As shown, the side wall of the supporting frame 1 is provided with two first mounting plates 11 arranged side by side, and both first mounting plates 11 are provided with first mounting holes for mounting the first drive motor 41; the side wall of the first frame 2 is provided with two second mounting plates 23 arranged side by side, and both second mounting plates 23 are provided with second mounting holes for mounting the second drive motor 51.

[0050] See Figures 1-2 As shown, the side wall of the supporting frame 1 is provided with a first hub slot 12. The first hub slot 12 and the first electric actuator 4 are arranged on the same side. The first hub slot 12 is used to organize and store a series of cables used to control the first electric actuator 4.

[0051] The side wall of the first frame 2 is provided with a second hub slot 24. The second hub slot 24 is located on the same side as the second electric actuator 5. The second hub slot 24 is used to organize and store a series of cables used to control the second electric actuator 5.

[0052] See Figure 3 As shown, each of the four corners of the supporting frame 1 is provided with an outwardly protruding fan-shaped structure 13. Each fan-shaped structure 13 is provided with at least two screw holes, which are used to cooperate with fasteners to fix the supporting frame 1 in the middle of the spherical sealed cabin 9. Rubber vibration isolation pads are installed below the fan-shaped structures 13. This design takes into account both low-frequency vibration isolation and high-frequency stiffness. At low frequencies, the rubber vibration isolation pads can absorb low-frequency attitude disturbances of the aircraft. At high frequencies, it can prevent the leveling mechanism from shifting inside the spherical sealed cabin 9, thereby avoiding the risk of collision between the leveling mechanism and the inner wall of the spherical sealed cabin 9.

[0053] See Figures 6-7 As shown, this embodiment also provides a gravimeter, which includes the above-mentioned leveling mechanism, gravity sensor 8 and spherical sealed chamber 9. The leveling mechanism is installed inside the spherical sealed chamber 9, and the gravity sensor 8 is installed inside the leveling mechanism.

[0054] In this embodiment, the spherical sealed chamber 9 is a three-section combined shell structure. Due to the isotropic force of the sphere, it can maintain minimal deformation in the high-pressure environment of the deep sea. The spherical sealed chamber 9 adopts a spherical design, which maximizes the space utilization while reducing the use of design materials, making the overall volume of the gravimeter smaller.

[0055] The upper, middle, and lower sections of the combined shell structure are each designed with 12 equally spaced bolt holes on their edges. The upper, middle, and lower shells are each fixed with 12 bolts, and the joints between the upper, middle, and lower shells are sealed with double O-rings. The surfaces of the upper, middle, and lower shells are all coated with anti-corrosion coatings to ensure the structural stability and performance reliability of the spherical sealed chamber 9 in the complex environment of the deep sea.

[0056] A support platform 91 is provided in the middle of the inner cavity of the spherical sealed chamber 9. The support platform 91 extends along the circumference of the spherical sealed chamber 9. The support platform 91 is used to support the four sector structures 13 of the support frame 1, and the four sector structures 13 are fixed to the support platform 91 by bolts.

[0057] The spherical sealed chamber 9 has a cable sealing interface at the rear of its middle section, through which internal cables communicate and transmit data with the outside.

[0058] The lower part of the spherical sealed chamber 9 is designed with a support bracket for mounting devices such as pressure gauge 92, thermometer 93, and DVL log 94. The pressure gauge 92, thermometer 93, DVL log 94, AC-DC converter 95, and storage module 96 are connected to the support bracket by bolts. This design facilitates installation and disassembly and effectively isolates the direct transmission of external pressure fluctuations and temperature changes to devices such as pressure gauge 92, thermometer 93, and DVL log 94, avoiding mechanical deformation of the devices and ensuring the measurement accuracy and operational reliability of the underwater gravity dynamic measurement system during long-term deep-sea operations.

[0059] See Figures 8-9 As shown, this application also provides an underwater gravity dynamic measurement system, including the above-mentioned gravimeter and mounting frame 10, with the gravimeter installed inside the mounting frame 10.

[0060] Specifically, the mounting frame 10 is a six-bar / truss type mounting frame, and the spherical sealed cabin 9 is connected to the underwater vehicle 100 (AUV / ROV) through the mounting frame 10. The mounting frame 10 is composed of multiple high-strength rods.

[0061] The base and the cross-section of the middle part of the mounting frame 10 are both regular hexagons, and the connection points are all thickened. The base and top of the mounting frame 10 form a hollow structure of a spatial triangular stabilizing system, which takes into account both structural strength and fluid permeability.

[0062] After testing, the leveling mechanism of this application has a leveling range of ±25°, which can adapt to a large range of attitude disturbances; the residual attitude angle can be controlled within 20 arcseconds, and the dynamic response time is less than 30 seconds, which enables the underwater gravity dynamic measurement system to have good real-time compensation capability, thereby ensuring that the gravimeter can maintain a high level reference in dynamic marine environments.

[0063] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural transformations made using the contents of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

Claims

1. A levelling mechanism characterised in that, The application relates to a levelling mechanism, which comprises a bearing frame, a first frame movably mounted in the bearing frame and capable of rotating around a first axis, a second frame movably mounted in the first frame and capable of rotating around a second axis, a first electric actuator for adjusting the roll angle of the first frame, and a second electric actuator for adjusting the pitch angle of the second frame. The first frame and the bearing frame are connected through a first rotating pair, the central axis of the first rotating pair coincides with the first axis, and the first rotating pair comprises a first shaft sleeve, and a first bearing, one of which is mounted on the first frame and the other of which is mounted on the bearing frame, and the first shaft sleeve is inserted into the bearing hole of the first bearing. The first frame and the second frame are connected through a second rotating pair, the central axis of the second rotating pair coincides with the second axis, and the second rotating pair comprises a second shaft sleeve, and a second bearing, one of which is mounted on the first frame and the other of which is mounted on the second frame, and the second shaft sleeve is inserted into the bearing hole of the second bearing. One side of the first frame is provided with a first linkage mechanism, the first electric actuator is mounted on the side wall of the bearing frame, and the first electric actuator is in contact with the first linkage mechanism. The first linkage mechanism comprises two first linkages mounted on the first frame, and a first arc-shaped piece, one end of which is connected with one of the first linkages and the other end of which is connected with the other first linkage. The arc-shaped opening of the first arc-shaped piece faces the first electric actuator, and the first electric actuator is arranged along the radial direction of the first arc-shaped piece.

2. Levelling mechanism according to claim 1, characterized in that One side of the second frame is provided with a second linkage mechanism, the second electric actuator is mounted on the side wall of the first frame, and the second electric actuator is in contact with the second linkage mechanism. The second linkage mechanism comprises two second linkages mounted on the second frame, and a second arc-shaped piece, one end of which is connected with one of the second linkages and the other end of which is connected with the other second linkage. The arc-shaped opening of the second arc-shaped piece faces the second electric actuator, and the second electric actuator is arranged along the radial direction of the second arc-shaped piece.

3. The leveling mechanism of claim 1, wherein, The bottom of the second frame is provided with a lifting structure, which comprises a connecting plate and a supporting plate, and the supporting plate and the second frame are connected through the connecting plate. The application further relates to a gravity sensor and a spherical sealed cabin body, wherein the levelling mechanism is mounted in the spherical sealed cabin body, and the gravity sensor is mounted in the levelling mechanism. ​ 4. The leveling mechanism of claim 1, wherein, ​ 5. Levelling mechanism according to claim 4, characterized in that ​ ​ ​ ​ 6. The leveling mechanism of claim 1, wherein, ​ 7. Levelling mechanism according to claim 6, characterized in that ​ ​ ​ ​ 8. The leveling mechanism of claim 1, wherein, ​ 9. A gravimeter characterized in that, ​ 10. An underwater gravity dynamic measurement system, characterized by, The gravimeter of claim 9 and a mounting frame, the gravimeter being mounted within the mounting frame.

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