A multi-degree-of-freedom propulsion structure for a seafloor mining robot

Abstract

This utility model relates to the field of seabed mining robot technology, specifically disclosing a multi-degree-of-freedom propulsion structure for a seabed mining robot. The structure is mounted on a base frame connected to the robot's main body and includes an installation mechanism and a propulsion mechanism. The installation mechanism has two sets of propellers symmetrically arranged on the left and right sides of the base frame. The propulsion mechanism includes multiple identical propellers, which are fixedly installed in groups by the installation mechanism to form horizontal propulsion unit groups and vertical propulsion unit groups. The horizontal propulsion unit groups are symmetrically distributed on both sides of the base frame and located at both ends of the horizontal travel direction of the base frame. Their thrust axes are on the same plane as the central axis of the base frame and form an acute angle with the horizontal travel direction axis. The vertical propulsion unit groups are symmetrically arranged on both sides of the base frame and located in the middle of the base frame. Their thrust axes are perpendicular to the plane containing the central axis of the base frame. This utility model achieves six degrees of freedom motion through a specific spatial layout of fixed propellers, and has advantages such as simple structure, high reliability, strong maneuverability, and precise control.

Description

Technical Field

[0001] This utility model relates to the field of seabed mining robot technology, specifically a multi-degree-of-freedom propulsion structure for a seabed mining robot. Background Technology

[0002] The ocean contains abundant polymetallic nodules, rich in strategic metals such as manganese, nickel, cobalt, and copper, representing a significant potential source for meeting future resource demands in fields like green energy and high-end manufacturing. Developing efficient and intelligent seabed mining technologies has become a global consensus for the commercial exploitation of these deep-sea resources. Among these technologies, small, intelligent mining robots capable of replacing traditional extensive towed mining methods and achieving refined operations are a crucial direction for technological development in this field. The performance of their underwater propulsion systems directly determines the robot's mobility, stability, and operational efficiency.

[0003] In the field of underwater robot propulsion technology, vector propulsion is an effective way to improve maneuverability. For example, Chinese Patent No. CN117657400A discloses a propeller structure, a vector propeller, and an underwater robot. This prior art achieves vector adjustment of the thrust of a single propeller by setting a first flow pipe and a second flow pipe that can rotate relative to each other, and by using a driving device to change the water outlet direction of the second flow pipe, thus providing the underwater robot with steering capability.

[0004] However, for small robots that need to perform precision mining tasks in complex seabed terrain, the above-mentioned scheme of achieving vector thrust by changing the direction of a single thruster nozzle relies on the rotation of the mechanical structure for thrust output adjustment. In scenarios requiring rapid and frequent attitude adjustments, there may be response delays. More importantly, the mobility of the entire system heavily depends on the coordinated actions of a few vector propulsion units, and the method of propulsion synthesis is relatively simple. When faced with multiple tasks that require simultaneous precise hovering, lateral maneuvering, and resistance to complex water currents, this vector propulsion method based on mechanical rotation still faces challenges in terms of flexibility, reliability, and multi-dimensional force control accuracy, making it difficult to fully meet the stringent requirements of small mining robots for high mobility and high stability in complex seabed environments. Utility Model Content

[0005] To address the technical problems in the prior art, this utility model provides a multi-degree-of-freedom propulsion structure for a seabed mining robot, aiming to solve the problems of complex mechanical structure and slow dynamic response of existing propulsion systems, which make it difficult to meet the high mobility and high stability requirements of small seabed mining robots.

[0006] The technical solution of this utility model is implemented as follows: A multi-degree-of-freedom propulsion structure for an underwater mining robot, connected to a base frame of the robot body, includes an installation mechanism and a propulsion mechanism, wherein... The installation mechanism is provided in two sets, symmetrically distributed on the left and right sides of the base frame; The propulsion mechanism includes multiple propellers with identical structures; Multiple thrusters are grouped and fixedly installed by the mounting mechanism to form a horizontal propulsion unit group and a vertical propulsion unit group; The horizontal propulsion unit groups are symmetrically distributed on both sides of the base frame and located at both ends of the base frame in the horizontal direction of travel; The thrust axis of the horizontal propulsion unit group is on the same plane as the central axis of the base frame, and the thrust axis of the horizontal propulsion unit group forms an acute angle with the horizontal travel direction axis of the base frame; The vertical propulsion unit group is symmetrically arranged on both sides of the base frame and located in the middle of the base frame; The thrust axis of the vertical propulsion unit is perpendicular to the plane containing the central axis of the base frame.

[0007] Optionally, the horizontal propulsion unit group includes four propellers; The four thrusters are symmetrically distributed on both sides of the base frame, and are located at both ends of the base frame in the horizontal direction of travel.

[0008] Optionally, the thrust axis of the thruster in the horizontal propulsion unit group forms a 45° angle with the central axis of the base frame.

[0009] Optionally, the vertical propulsion unit group includes four propellers; The four thrusters are symmetrically distributed on both sides of the base frame and located in the middle of the base frame respectively. The thrust axis of the thruster in the vertical thrust unit group is perpendicular to the plane containing the central axis of the base frame.

[0010] Optionally, each set of the installation mechanisms includes two, which are respectively located at both ends of the base frame in the horizontal travel direction; The installation mechanism includes a mounting base and a mounting arm, wherein, The mounting base is fixedly disposed at the end of the base frame; The mounting arm is fixedly installed on the mounting base and is used to be fixedly connected to the corresponding thruster.

[0011] Optionally, the mounting base is integrally formed with the base frame.

[0012] Optionally, the mounting arm includes a horizontal mounting arm and a vertical mounting arm, wherein, The horizontal mounting arm extends horizontally from the mounting base to the outer end of the base frame and is used to fix and connect the thruster in the horizontal propulsion unit group. The vertical mounting arm extends horizontally from the mounting base toward the middle of the base frame and is used to fix and connect the thruster in the vertical propulsion unit group.

[0013] Optionally, the thruster includes a protective shield, a brushless motor, and a propeller, wherein, The protective cover is fixedly connected to the installation mechanism; The brushless motor is fixedly installed inside the protective cover; The propeller is connected to the output shaft of the brushless motor via a drive connection.

[0014] Optionally, the protective cover has a streamlined design that helps reduce fluid resistance.

[0015] Optionally, the propeller is a three-bladed propeller, wherein the pitch of the blades increases continuously from the hub to the tip.

[0016] Compared with the prior art, the multi-degree-of-freedom propulsion structure for a seabed mining robot provided by this utility model has the following advantages: (1) Multiple thrusters with identical structures and fixed installations are used to synthesize the required thrust vector through a preset, immovable spatial geometry layout. This eliminates all rotating seals, drive motors and transmission mechanisms, thereby eliminating the most vulnerable links in the deep-sea high-pressure environment and greatly improving the structural simplicity, operational reliability and environmental durability of the entire propulsion system.

[0017] (2) Since the change of thrust direction depends entirely on the rapid and independent adjustment of the thrust magnitude of the fixed thruster by the electrical signal, rather than the physical rotation of the mechanical structure, mechanical inertia and transmission delay are avoided; this enables the robot to achieve millisecond-level dynamic response, meet the high-frequency and precise closed-loop control requirements for attitude and position under complex seabed currents and rugged terrain, and lay the core capability foundation for realizing precision mining operations.

[0018] (3) By dividing the thrusters into horizontal thruster units and vertical thruster units and adopting an innovative 45° symmetrical layout, true six-degree-of-freedom omnidirectional motion control is achieved: the horizontal thruster units generate linear thrust through collaborative work and generate rotational torque through independent work on one side; the vertical thruster units provide stable heave and attitude adjustment capabilities; this thrust synthesis scheme based on fixed-angle thruster layout enables the robot to achieve precise lateral movement, in-situ rotation and multi-dimensional attitude adjustment in narrow and complex seabed terrain, and its maneuverability far exceeds that of traditional vector propulsion schemes.

[0019] (4) The combined effect of the streamlined protective cover of the propeller body, the anti-mud and sand filter screen, and the optimized design of the three-bladed propeller with the pitch of the blades continuously increasing from the hub to the tip effectively reduces fluid resistance, suppresses cavitation effect, and reduces the intake and adhesion of seabed mud and sand, thus maintaining high propulsion efficiency and long service life in complex and turbid operating environments. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of a multi-degree-of-freedom propulsion structure for a seabed mining robot according to the present invention; Figure 2 This is a top view schematic diagram of a multi-degree-of-freedom propulsion structure for an underwater mining robot according to this utility model; Figure 3 for Figure 2 Enlarged view of point A in the middle; Figure 4 This is a schematic diagram of the thruster structure of a multi-degree-of-freedom propulsion structure for an underwater mining robot according to this utility model.

[0021] In the diagram: 1. Base frame; 2. Mounting mechanism; 21. Mounting base; 22. Mounting arm; 221. Horizontal mounting arm; 222. Vertical mounting arm; 3. Thruster; 301. Horizontal propulsion unit group; 302. Vertical propulsion unit group; 31. Protective cover; 32. Brushless motor; 33. Propeller. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0023] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model based on the specific circumstances.

[0024] In the description of the embodiments of this utility model, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this utility model.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0027] The following disclosure provides numerous different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0028] Please see Figure 1-4 The present invention proposes a multi-degree-of-freedom propulsion structure for a seabed mining robot, which is connected to the base frame 1 of the robot body and includes an installation mechanism 2 and a propulsion mechanism.

[0029] like Figure 1-2As shown, the installation mechanism 2 has two sets, symmetrically distributed on the left and right sides of the base frame 1; the propulsion mechanism includes multiple propellers 3 with the same structure; the multiple propellers 3 are grouped and fixedly installed through the installation mechanism 2 to form a horizontal propulsion unit group 301 and a vertical propulsion unit group 302; the horizontal propulsion unit group 301 is symmetrically distributed on both sides of the base frame 1 and located at both ends of the horizontal travel direction of the base frame 1; the thrust axis of the horizontal propulsion unit group 301 is on the same plane as the central axis of the base frame 1, and the thrust axis of the horizontal propulsion unit group 301 forms an acute angle with the horizontal travel direction axis of the base frame 1; the vertical propulsion unit group 302 is symmetrically arranged on both sides of the base frame 1 and located in the middle of the base frame 1; the thrust axis of the vertical propulsion unit group 302 is perpendicular to the plane containing the central axis of the base frame 1.

[0030] Specifically, the innovative grouping layout achieves complete decoupling of the six degrees of freedom motion; the horizontal propulsion unit group 301 adopts a symmetrical layout at both ends of the base frame 1, and can simultaneously achieve forward, backward, lateral, and yaw control through thrust vector synthesis; the vertical propulsion unit group 302 is arranged in the middle of the base frame 1, and is specifically responsible for heave, pitch, and roll motion; this spatial layout avoids coupling interference between the various degrees of freedom motions. Compared with the existing technology that uses movable vector thrusters, this structure simplifies the mechanical structure and improves the system reliability through the coordinated work of fixed thrusters; in practical applications, the existing control system sends control commands to each thruster 3 via the CAN bus, and calculates the thrust requirements of each thruster 3 in real time according to the inverse kinematics model, thereby achieving precise motion control.

[0031] In some embodiments, such as Figure 1-2 As shown, the horizontal propulsion unit group 301 includes four propellers 3; the four propellers 3 are symmetrically distributed on both sides of the base frame 1 and are located at both ends of the horizontal travel direction of the base frame 1 respectively.

[0032] Specifically, the symmetrical layout of the four thrusters 3 is the key to achieving efficient thrust synthesis; the two thrusters 3 at the front end and the two thrusters 3 at the rear end form a force couple. When forward movement is required, all thrusters 3 work simultaneously, and the projections of their symmetrical angle thrusts on the plane are superimposed to generate a powerful forward thrust; when lateral movement is required, it can be achieved by adjusting the thrust difference between the left and right thrusters 3. This layout makes full use of the geometric characteristics of the base frame 1, so that the thrust application point is reasonably distributed and unnecessary torque interference is avoided.

[0033] In some embodiments, such as Figure 2 As shown, the thrust axis of the thruster 3 in the horizontal propulsion unit group 301 forms a 45° angle with the central axis of the base frame 1.

[0034] Specifically, the optimized design of the 45° included angle is one of the core innovations of this invention. Specifically, when the thruster 3 is installed at a 45° angle, its thrust can be decomposed into a component parallel to the central axis of the base frame 1 and a component perpendicular to the central axis. The magnitudes of these two components are equal, enabling the robot to perform forward and lateral movements with the same control efficiency. In actual control, the motion controller of the prior art calculates the desired velocity vector and decomposes it into the thrust set value of each thruster 3. The thrust distribution module calculates the rotational speed command of each thruster 3 according to the preset distribution algorithm, thereby achieving precise vector control.

[0035] In some embodiments, such as Figure 1-2 As shown, the vertical propulsion unit group 302 includes four thrusters 3; the four thrusters 3 are symmetrically distributed on both sides of the base frame 1 and are located in the middle of the base frame 1 respectively. The thrust axis of the thruster 3 in the vertical propulsion unit group 302 is perpendicular to the plane containing the central axis of the base frame 1.

[0036] Specifically, the four thrusters 3 of the vertical propulsion unit group 302 are arranged on the left and right sides of the middle of the base frame 1. This layout ensures the uniform distribution of heave force and attitude control torque. When the four thrusters 3 operate at the same speed, pure heave motion is generated. When the front and rear thrusters 3 have a speed difference, pitch control is achieved. When the left and right thrusters 3 have a speed difference, roll control is achieved. The vertical installation of the thrusters 3 avoids coupling with horizontal motion and simplifies the design of the control algorithm. The system uses high-precision attitude sensors to monitor the robot's attitude changes in real time, forming a closed-loop control to ensure that it can maintain a stable operating attitude under complex ocean current interference.

[0037] In some embodiments, such as Figure 2-3 As shown, each set of mounting mechanisms 2 includes two, which are respectively located at both ends of the base frame 1 in the horizontal travel direction; the mounting mechanism 2 includes a mounting base 21 and a mounting arm 22. The mounting base 21 is fixedly located at the end of the base frame 1 and integrally formed therewith; the mounting arm 22 is fixedly mounted on the mounting base 21 and is used to be fixedly connected to the corresponding thruster 3.

[0038] Specifically, the installation mechanism 2 adopts a modular integrated design; the installation base 21 and the base frame 1 are manufactured using an integral casting process, with high-strength aluminum alloy or stainless steel being the preferred materials; this integrated structure eliminates the risk of loosening associated with traditional bolt connections, significantly improving overall rigidity and stability; the installation support arm 22 is precision machined and fixed to the installation base 21 using a flange connection; the surface of the support arm is treated with anti-corrosion measures to improve corrosion resistance; each installation support arm 22 has a standardized interface at its end, equipped with a waterproof electrical connector, facilitating the rapid installation and maintenance of the pusher 3.

[0039] In some embodiments, such as Figure 3As shown, the mounting arm 22 includes a horizontal mounting arm 221 and a vertical mounting arm 222. The horizontal mounting arm 221 extends horizontally from the mounting base 21 to the outer end of the base frame 1 and is used to fix the thruster 3 in the horizontal propulsion unit group 301. The vertical mounting arm 222 extends horizontally from the mounting base 21 to the middle of the base frame 1 and is used to fix the thruster 3 in the vertical propulsion unit group 302.

[0040] Specifically, the division of labor between the horizontal mounting arm 221 and the vertical mounting arm 222 enables precise positioning of the thruster. The horizontal mounting arm 221 adopts a cantilever beam structure, and its length has been optimized to ensure that the thrust generated by the horizontal thruster 3 has a suitable lever arm, thereby efficiently generating yaw torque. The vertical mounting arm 222 adopts a short arm design, placing the vertical thruster 3 close to the central axis of the base frame 1, which can reduce the additional torque generated during heave motion. Both types of arms are optimized using finite element analysis, achieving lightweight design while ensuring rigidity.

[0041] In some embodiments, such as Figure 4 As shown, the thruster 3 includes a protective cover 31, a brushless motor 32, and a propeller 33. The protective cover 31 is fixedly connected to the mounting mechanism 2; the brushless motor 32 is fixedly installed inside the protective cover 31; and the propeller 33 is drively connected to the output shaft of the brushless motor 32.

[0042] Specifically, the integrated design of the thruster 3 ensures its reliable operation in underwater environments; the protective cover 31 is made of corrosion-resistant metal material and filled with pressure-compensating oil to balance internal and external pressures and protect the brushless motor 32 from the high pressure of the deep sea; the brushless motor 32 is a low-speed, high-torque model, combined with magnetic coupling sealing technology, to achieve a completely leak-free shaft seal design; the propeller 33 is CNC machined to ensure consistent blade shape accuracy; as a preferred solution, multiple sealing rings are installed between the output shaft of the brushless motor 32 and the hub of the propeller 33 to effectively prevent sediment intrusion; at the same time, a removable sediment filter is installed at the inlet of the protective cover 31 to intercept larger particles of impurities and protect the internal rotating parts.

[0043] In some embodiments, such as Figure 4 As shown, the protective cover 31 is streamlined to reduce fluid resistance.

[0044] Specifically, the streamlined shape of the protective shield 31 has been optimized for hydrodynamics, and its length-to-diameter ratio has been specially designed. The front end adopts an oval curve, and the rear end adopts a gradually tapering tail cone design. This shape can effectively reduce the shape drag of the thruster 3 during the movement process, while avoiding flow separation on the surface of the protective shield 31. The surface of the protective shield 31 has also been polished to further reduce surface friction resistance. This streamlined design improves propulsion efficiency and extends endurance.

[0045] In some embodiments, such as Figure 4 As shown, propeller 33 is a three-bladed propeller, and the pitch of its blades increases continuously from the hub to the tip.

[0046] Specifically, in this embodiment, the propeller 33 adopts a three-bladed design; this design achieves the best balance between propulsion efficiency and anti-cavitation performance. The blades of the propeller 33 adopt a special variable pitch design, with the pitch continuously increasing from the hub to the blade tip. This design allows the water flow to maintain the best angle of attack distribution at different radii of the blades, thereby obtaining a uniform load distribution on the entire propeller disk surface.

[0047] Specifically, a smaller pitch is used near the blade hub to accommodate lower linear velocities, while the pitch gradually increases towards the blade tip to match higher linear velocities. This variable pitch design effectively reduces the load on the blade tip, reduces eddy currents, and significantly suppresses cavitation. At the same time, this design also improves propulsion efficiency, reduces energy loss, and allows water to flow more smoothly across the blade disk.

[0048] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-degree of freedom propulsion structure for a seabed mining robot, connected to a base frame (1) of a robot body, characterized in that, Includes an installation mechanism (2) and a propulsion mechanism, wherein, The installation mechanism (2) is provided in two sets, symmetrically distributed on the left and right sides of the base frame (1); The propulsion mechanism includes multiple propellers (3) with the same structure. Multiple thrusters (3) are grouped and fixedly installed by the mounting mechanism (2) to form a horizontal thrust unit group (301) and a vertical thrust unit group (302). The horizontal propulsion unit group (301) is symmetrically distributed on both sides of the base frame (1) and located at both ends of the horizontal travel direction of the base frame (1); The thrust axis of the horizontal propulsion unit group (301) is on the same plane as the central axis of the base frame (1), and the thrust axis of the horizontal propulsion unit group (301) forms an acute angle with the horizontal travel direction axis of the base frame (1). The vertical propulsion unit group (302) is symmetrically arranged on both sides of the base frame (1) and located in the middle of the base frame (1); The thrust axis of the vertical propulsion unit group (302) is perpendicular to the plane containing the central axis of the base frame (1).

2. The multi-degree-of-freedom propulsion structure for a seabed mining robot according to claim 1, characterized in that, The horizontal propulsion unit group (301) includes four propellers (3); The four propellers (3) are symmetrically distributed on both sides of the base frame (1) and located at both ends of the horizontal travel direction of the base frame (1).

3. A multi-degree of freedom propulsion structure for a seafloor mining robot according to claim 2, wherein, The thrust axis of the thruster (3) in the horizontal propulsion unit group (301) forms a 45° angle with the central axis of the base frame (1).

4. The multi-degree-of-freedom propulsion structure for a seabed mining robot according to claim 1, characterized in that, The vertical propulsion unit group (302) includes four propellers (3); The four thrusters (3) are symmetrically distributed on both sides of the base frame (1) and located in the middle of the base frame (1). The thrust axis of the thruster (3) in the vertical thrust unit group (302) is perpendicular to the plane containing the central axis of the base frame (1).

5. The multi-degree of freedom propulsion structure for a seafloor mining robot according to claim 1, wherein, Each set of installation mechanisms (2) includes two, which are respectively located at both ends of the base frame (1) in the horizontal direction of travel; The installation mechanism (2) includes a mounting base (21) and a mounting arm (22), wherein, The mounting base (21) is fixedly disposed at the end of the base frame (1); The mounting arm (22) is fixedly mounted on the mounting base (21) for fixed connection with the corresponding thruster (3).

6. A multi-degree-of-freedom propulsion structure for a seabed mining robot according to claim 5, characterized in that, The mounting base (21) is integrally formed with the base frame (1).

7. A multi-degree of freedom propulsion structure for a seafloor mining robot according to claim 5, wherein, The mounting arm (22) includes a horizontal mounting arm (221) and a vertical mounting arm (222), wherein, The horizontal mounting arm (221) extends horizontally from the mounting base (21) to the outer side of the end of the base frame (1) for fixing the thruster (3) in the horizontal propulsion unit group (301). The vertical mounting arm (222) extends horizontally from the mounting base (21) toward the middle of the base frame (1) for fixing the thruster (3) in the vertical propulsion unit group (302).

8. A multi-degree of freedom propulsion structure for a seafloor mining robot according to any one of claims 1 to 7, wherein, The thruster (3) includes a protective cover (31), a brushless motor (32), and a propeller (33), wherein, The protective cover (31) is fixedly connected to the mounting mechanism (2); The brushless motor (32) is fixedly installed inside the protective cover (31); The propeller (33) is connected to the output shaft of the brushless motor (32) via a drive connection.

9. The multi-degree-of-freedom propulsion structure for a seabed mining robot according to claim 8, characterized in that, The protective cover (31) has a streamlined design that helps reduce fluid resistance.

10. A multi-degree of freedom propulsion structure for a seafloor mining robot according to claim 8, wherein, The propeller (33) is a three-bladed propeller, and the pitch of its blades increases continuously from the hub to the tip.

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