Magnetic gear transmission-based bionic robotic fish using static sealing and joint module thereof

Abstract

A magnetic gear transmission-based bionic robotic fish using static sealing and a joint module thereof. The joint module comprising a housing (101) and a magnetic gear assembly; the housing (101) comprises a waterproof sealed space, and the upper side and the lower side of the housing (101) respectively extend to form a first connection plate (102) and a second connection plate (103); the magnetic gear assembly comprises an input magnetic gear (12) arranged in the waterproof sealed space, modulation blocks (9), and an output magnetic gear (10) arranged on the first connection plate (102); and the upper and lower side surfaces of the housing (101), the first connection plate (102) and the second connection plate (103) are respectively provided with mounting structures for mounting rotary components. In the present invention, there is no need to use a rotary dynamic sealing structure, thereby avoiding use of a complex dynamic sealing structure or a high-cost customized waterproof motor, reducing the design / assembly difficulty, and improving the reliability of the bionic robotic fish.

Description

A bionic robotic fish with magnetic gear transmission and static seal and its joint module Technical Field

[0001] The present invention relates to the technical field of bionic robots, in particular to a bionic robotic fish with statically sealed magnetic gear transmission and a joint module thereof. Background Art

[0002] Compared with underwater robots propelled by propellers (such as AUVs, ROVs, etc.), bionic robotic fish that use the principle of body wave propulsion have a series of advantages such as strong maneuverability, high movement efficiency, low movement noise, and environmental friendliness. They have been widely studied in recent years and have broad application prospects in science, education and entertainment, water quality monitoring, ecological and environmental protection, rare aquaculture, and special reconnaissance.

[0003] The body of a bionic robotic fish is typically composed of reciprocating joints. The amplitude and frequency of the joints' reciprocating oscillations determine the robot's speed and, therefore, its performance. To ensure high performance and durability, the joints must possess both high torque output (the torque required by the joints is proportional to the square of the oscillation frequency) and overload protection (overload is easily caused by the reciprocating oscillations and frequent acceleration and deceleration of the joints). Furthermore, the joint modules must possess excellent waterproof sealing properties to prevent wear and tear of rotating seal components, circuit board shorts caused by water seepage, and internal corrosion. Meeting these requirements simultaneously is crucial for the design and application of robotic fish.

[0004] Common propeller waterproof drive motors are typically brushless DC motors (BLDCs), which only require speed control and operate at high speeds, resulting in low motor output torque. However, for bionic robotic fish, the motors typically need to operate in position control or torque control mode, and the joint output torque is high, which waterproof propeller drive motors cannot meet. To ensure efficient movement of robotic fish in wading environments, the following three solutions are currently used:

[0005] (1) The joint module adopts a waterproof servo solution, and the control circuit part adopts a static seal

[0006] On the one hand, this solution requires a custom waterproof servo, making its processing and manufacturing process difficult to guarantee. On the other hand, the servo's control function is relatively simple and its performance is unstable, capable only of position control. (To ensure the bionic fish's movement efficiency, it should also be able to control torque to support joint compliance.) These shortcomings often lead to the robotic fish experiencing problems such as grinding or jamming of the reduction gear teeth due to transient overloads (such as accelerating, turning too sharply, etc.), as well as stiff rotation and inflexible movement. This significantly reduces the overall reliability and smoothness of the robotic fish.

[0007] (2) The joint module adopts the motor + mechanical reducer + rotary dynamic seal solution

[0008] The rotary seal components of this solution are either complex in structure, require high precision in processing and assembly (especially for mechanical seals), or have high friction resistance (such as O-rings), making it difficult to achieve reliable sealing for a long time.

[0009] (3) The bionic robot fish body adopts a waterproof outer shell as the overall sealing solution

[0010] In this solution, a waterproof outer garment not only limits the range of motion of the joints and increases resistance, but also poses risks of wear and tear after repeated use, as well as scratches from sharp objects on the surface of the water. If the outer garment were to cover the entire robotic fish, heat dissipation would be difficult, leading to electrical control system shutdown or damage due to overheating after prolonged operation (>10 minutes).

[0011] A research team at the Biorobotics Institute at the University of Santa Ana applied the contactless and overload-protective advantages of magnetic transmission to a bionic robotic fish. By cleverly arranging the spatial placement of permanent magnets, they converted the motor's continuous rotational motion into reciprocating oscillation of components. This oscillation of a single joint was then transmitted to the entire body of the robotic fish via a wire drive, enabling the bionic robotic fish to swim with undulating motion. However, to maintain a certain oscillation angle, the distances between the permanent magnets in this magnetic transmission structure varied significantly, resulting in a low output torque for the joints. Furthermore, this solution cannot adjust the amplitude of the robotic fish's oscillation and is only suitable for micro-scale bionic robotic fish using wire drives.

[0012] Summary of the Invention

[0013] The main purpose of the present invention is to solve the problem that the rotary dynamic seal of the existing bionic robotic fish joint module is prone to failure.

[0014] Another object of the present invention is to solve the problems of short-term overload and insufficient motor output torque of existing bionic robotic fish.

[0015] To achieve the above object, the technical solution of the present invention is:

[0016] The first aspect of the present invention provides a joint module of a bionic robotic fish, comprising a shell and a magnetic gear assembly; the shell comprises a waterproof sealed space, and the upper and lower sides of the shell extend respectively to form a first connecting plate and a second connecting plate; the magnetic gear assembly comprises an input magnetic gear, a modulation block, and an output magnetic gear arranged in the waterproof sealed space; the upper and lower side surfaces of the shell, the first connecting plate, and the second connecting plate are respectively provided with mounting structures for installing rotating parts, so that the two joint modules can realize joint connection by forming a rotating pair with the rotating parts installed on the first connecting plate and the second connecting plate of the other joint module through the rotating parts installed on the upper and lower sides of the shell of one joint module, and the output magnetic gear in the other joint module is driven to rotate by the input magnetic gear in one joint module to realize joint movement.

[0017] In other embodiments, the central axes of the revolute pair for achieving joint connection, the input magnetic gear and modulation block of one joint module, and the output magnetic gear of another joint module are coaxial.

[0018] In other embodiments, the shell includes a base, an upper cover and a sealing ring, the base has a cavity, and a second connecting plate extends along one side of the cavity to form; the upper cover is arranged above the base to cover the cavity, and one side of the upper cover extends to form a first connecting plate arranged opposite to the second connecting plate; the sealing material is arranged between the upper cover and the base to seal the cavity into a waterproof sealed space.

[0019] In other embodiments, the magnetic gear assembly further includes a motor disposed in the cavity, a gear mounting plate fixedly mounted on the motor, the gear mounting plate including a plurality of fan-shaped or trapezoidal mounting grooves evenly arranged along the circumferential direction, and the input magnetic gear including a plurality of magnets correspondingly fixedly mounted in the mounting grooves.

[0020] In other embodiments, the magnetic gear assembly further includes a battery and a control board disposed in the cavity, which are electrically connected to the motor respectively.

[0021] In other embodiments, a plurality of mounting grooves are evenly arranged along the circumferential direction on the lower surface of the upper cover, and a plurality of modulation blocks are correspondingly fixedly installed in the mounting grooves; a plurality of mounting grooves are evenly arranged along the circumferential direction on the lower surface of the first connecting plate, and the input magnetic gear includes a plurality of magnets correspondingly fixedly installed in the mounting grooves.

[0022] In other embodiments, a blind hole is provided on the upper surface of the upper cover, a bearing is embedded in the blind hole, the first connecting plate is provided with a stepped through hole for installing a flange shaft, and the size of the flange shaft is adapted to the bearing to form a revolute pair when the two joint modules are articulated.

[0023] In other embodiments, the lower surface of the base is provided with a mounting hole for installing a sleeve, and the second connecting plate is provided with a mounting hole for installing a rotating shaft. The size of the sleeve is adapted to the rotating shaft to form a rotating pair when the two joint modules are connected.

[0024] The second aspect of the present invention provides a bionic robotic fish, comprising at least two of the aforementioned joint modules, wherein the two joint modules are connected to the joint by forming a rotating pair through rotating parts installed on the upper and lower sides of the shell of one joint module and rotating parts installed on the first connecting plate and the second connecting plate of the other joint module, respectively, and the joint movement is achieved by driving the output magnetic gear in the other joint module to rotate through the input magnetic gear in one joint module.

[0025] In other embodiments, one of the joint modules does not have an input magnetic gear and a modulation block set in a waterproof sealed space.

[0026] Compared with the existing solutions, the present invention has the following beneficial effects:

[0027] (1) The present invention does not require the use of a rotating dynamic sealing structure, thus avoiding a complex dynamic sealing structure or a high-cost customized waterproof motor, reducing the difficulty of design / assembly, and improving the reliability of the bionic robotic fish.

[0028] (2) The magnetic gear assembly used in the present invention can be used in conjunction with a mature joint motor, and can also directly replace a mechanical planetary reduction gear, thereby greatly simplifying the joint module structure;

[0029] (3) The joint module of the present invention using magnetic gears has an automatic overload protection function, which can effectively protect the reducer and motor during sudden acceleration or sharp turns.

[0030] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0032] In the attached figure:

[0033] FIG1 is a schematic diagram of the overall structure of a joint module according to an embodiment of the present invention;

[0034] FIG2 is a schematic structural diagram of a joint module upper cover and a portion of a magnetic gear assembly according to an embodiment of the present invention;

[0035] 3 is a schematic structural diagram of a joint module base and a portion of a magnetic gear assembly according to an embodiment of the present invention;

[0036] FIG4 is a schematic diagram of the joint connection structure of two joint modules;

[0037] FIG5 is an exploded view of two joint modules connected by joints;

[0038] Figures 6 and 7 are schematic diagrams of the motion of the robotic fish joint module. DETAILED DESCRIPTION

[0039] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. It should be understood that the embodiments described are only some of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention, its application, or use.

[0040] Figures 1-3 exemplarily illustrate the joint module structure according to an embodiment of the present invention. As shown in Figures 1-3, the present invention provides a joint module of a bionic robotic fish, comprising:

[0041] The housing 101 includes a waterproof sealed space. A first connecting plate 102 is extended from the upper side of the housing, and a second connecting plate 103 is extended from the lower side of the housing.

[0042] The magnetic gear assembly includes an input magnetic gear 12 arranged in a waterproof sealed space, a modulation block 9 and an output magnetic gear 10 arranged on a first connecting plate.

[0043] In the present invention, the upper and lower side surfaces of the shell 101, the first connecting plate 102 and the second connecting plate 103 are respectively provided with mounting structures for installing rotating parts, so that the two joint modules 100 and 200 can realize joint connection by forming a rotating pair through the rotating parts installed on the upper and lower side surfaces of the shell of one joint module 200 and the rotating parts installed on the first connecting plate and the second connecting plate of the other joint module 100, and realize joint movement by driving the output magnetic gear in the other joint module 100 to rotate through the input magnetic gear in one joint module 200, as shown in Figure 4.

[0044] In the present invention, as shown in FIG1-4 , the central axes of the revolute pair for realizing joint connection, the input magnetic gear and modulation block of one joint module 200 and the output magnetic gear of another joint module 100 are coaxial.

[0045] Continuing to refer to Figures 2, 3, and 5, the housing includes a base 16, an upper cover 8, and a sealing ring 2. The base 16 has a cavity, and the second connecting plate 103 mentioned above is extended along one side of the cavity. The upper cover 8 is arranged above the base 16 to cover the cavity, and one side thereof extends to form a first connecting plate 102 arranged opposite to the second connecting plate 103. A sealing material, such as a rubber sealing ring, is arranged between the upper cover 8 and the base 16 to seal the cavity into a waterproof sealed space. For example, an annular groove for positioning the sealing material is provided at the connection between the upper cover 8 and the base 16.

[0046] In the present invention, the magnetic gear assembly further includes a motor 15 disposed within the cavity and a gear mounting plate 13 fixedly mounted on the motor 15. The gear mounting plate 13 includes a plurality of sector-shaped or trapezoidal mounting slots uniformly arranged along the circumference. The input magnetic gear 12 includes a plurality of magnets fixedly mounted (e.g., clipped) within the corresponding mounting slots.

[0047] The magnetic gear assembly also includes a battery 18 and a control board 17, both of which are electrically connected to the motor 15. Battery 18 powers the motor and control board, while control board 17 controls the motor's operating parameters, thereby controlling the torque and speed output by the magnetic gear assembly.

[0048] For example, as shown in the figure, motor 15 is mounted in a slot within the housing of base 16 and secured by bolts 14. Input magnetic gear 12 is mounted in a corresponding slot in input magnetic gear mounting plate 13, which is secured to the output shaft of motor 15 by bolts 11. Battery 18 is placed at the bottom of the housing of base 16, with control board 17 positioned above battery 18.

[0049] As shown in Figure 2, in the present invention, the lower surface of the upper cover 8 is provided with multiple mounting grooves evenly spaced along the circumference, and the multiple modulation blocks 9 are fixedly mounted in the corresponding mounting grooves. The lower surface of the first connecting plate 102 is also provided with multiple mounting grooves evenly spaced along the circumference, and the output magnetic gear 10 includes multiple magnets fixedly mounted in the corresponding mounting grooves. As shown in the figure, all of these mounting grooves include a bottom, meaning that the mounting grooves do not extend through the upper cover or the first connecting plate.

[0050] It should be noted that the materials and structures of the magnets, modulation blocks and other components of the above-mentioned magnetic gear assembly, including the control method of the magnetic gear assembly by the control board, are all known technologies to those skilled in the art, and the present invention does not impose additional restrictions on them. Therefore, the specific technical content will not be repeated in the present invention.

[0051] The upper surface of the upper cover 8 is provided with a blind hole, into which a bearing 7 is embedded (i.e., a non-through hole including the bottom of the hole). The first connecting plate 102 is provided with a stepped through hole for mounting the flange shaft 4. The size of the flange shaft 4 is adapted to the bearing 7, thereby forming a revolute pair when the two joint modules are articulated. As shown in the figure, when the two joint modules are connected, the flange shaft 4 is inserted into the through hole of the first connecting plate and secured with bolts 3. At the same time, the flange shaft 4 is inserted into the bearing hole of the other joint module provided on the upper cover, allowing the two joint modules to rotate around the flange shaft 4.

[0052] The lower surface of the base 16 is provided with a mounting hole for mounting the sleeve 5. The second connecting plate 103 is provided with a mounting hole for mounting the shaft 6. The size of the sleeve 5 is adapted to the shaft 6 to form a revolute pair when the two joint modules are articulated.

[0053] 4-7 , and in combination with FIG1-3 , the present invention provides a bionic robotic fish, comprising at least two of the aforementioned joint modules 100, 200. The two joint modules 100, 200 are connected to each other by rotating parts installed on the upper and lower sides of the shell of one joint module, respectively forming a rotating pair with rotating parts installed on the first connecting plate and the second connecting plate of the other joint module. Joint movement is achieved by driving the output magnetic gear in the other joint module to rotate through the input magnetic gear in one joint module.

[0054] In the present invention, a bionic robotic fish using magnetic gear transmission generates propulsion waves through the mutual rotation of its joints, thereby moving forward. Specifically, as shown in Figures 6 and 7, when the second joint module 200 rotates around the first joint module 100 with equal amplitude and frequency, it generates an anti-Kármán vortex street (an anti-Kármán vortex street refers to a vortex that rotates in the opposite direction when a fluid rotates under certain conditions), thereby propelling the fish forward. When the second joint module 200 rotates around the first joint module 100 with unequal amplitude but equal frequency, it propels the fish to turn.

[0055] It can be understood that the bionic robotic fish provided by the present invention can be composed of multiple joint modules connected end to end, and each joint module can have the same or different sizes and shapes. Power transmission between adjacent joint modules is achieved through magnetic gears.

[0056] Furthermore, the head or tail of the robotic fish, connected end to end, do not require power output. Therefore, the corresponding joint modules can be free of components such as input magnetic gears and modulation blocks, reducing the weight of the robotic fish and lowering manufacturing costs.

[0057] Regarding the waterproof (dynamic sealing) requirements of the motion joint modules of robotic fish or other forms of articulated underwater robots, existing solutions have problems with reliability, durability and motion performance. The present invention adopts a magnetic gear assembly as a power transmission mechanism, and there is no need to set a sealing structure in the power transmission path. By utilizing the advantages of the contactless transmission of magnetic gears, the underwater working requirements of the robotic fish can be met only by setting a static seal for sealing the shell, avoiding the use of complex dynamic sealing structures or high-cost customized waterproof joint motors, and fundamentally circumventing the defects of waterproof dynamic sealing.

[0058] At the same time, in response to the joint torque output (low-speed high torque, instantaneous explosive force) and control (position control or torque control) requirements of robotic fish or other forms of articulated underwater robots, existing technical solutions either directly use high-torque output servos or use servo torque motors + reducers + dynamic seal structures. The present invention can directly use magnetic gears for deceleration, while taking into account waterproof sealing and overload protection requirements, greatly reducing the difficulty of joint module structural design and assembly. At the same time, the magnetic gear reduction ratio can be flexibly configured as needed based on the original motor output capacity to adapt to different application scenarios.

[0059] In the present invention, the magnetic gear can be used in conjunction with a mature joint motor (such as Xiaomi's Cyber-gear), or it can directly replace the mechanical planetary reduction gear and be used in conjunction with a frameless torque motor, thereby further simplifying the joint module structure.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents; without departing from the spirit of the technical solutions of the present invention, they should all be included in the scope of the technical solutions for which protection is sought in the present invention.

Claims

1. A joint module of a bionic robotic fish, characterized in that: It includes a shell and a magnetic gear assembly; the shell includes a waterproof sealed space, and the upper and lower sides of the shell extend respectively to form a first connecting plate and a second connecting plate; the magnetic gear assembly includes an input magnetic gear, a modulation block and an output magnetic gear arranged on the first connecting plate arranged in the waterproof sealed space; the upper and lower side surfaces of the shell, the first connecting plate and the second connecting plate are respectively provided with mounting structures for installing rotating parts, so that two joint modules can realize joint connection through rotating parts installed on the upper and lower sides of the shell of one joint module and rotating parts installed on the first connecting plate and the second connecting plate of the other joint module respectively to form a rotating pair, and realize joint movement by driving the output magnetic gear in the other joint module to rotate through the input magnetic gear in one joint module.

2. The joint module according to claim 1, characterized in that: The central axes of the revolute pair, the input magnetic gear and the modulation block of one joint module and the output magnetic gear of another joint module that realize the joint connection are coaxial.

3. The joint module according to claim 2, characterized in that: The shell includes a base, an upper cover and a sealing ring. The base has a cavity, and a second connecting plate is extended along one side of the cavity. The upper cover is arranged above the base to cover the cavity, and one side of the upper cover extends to form a first connecting plate arranged opposite to the second connecting plate. The sealing material is arranged between the upper cover and the base to seal the cavity into a waterproof sealed space.

4. The joint module according to claim 3, characterized in that: The magnetic gear assembly also includes a motor arranged in the cavity, a gear mounting plate fixedly mounted on the motor, the gear mounting plate including a plurality of fan-shaped or trapezoidal mounting grooves evenly arranged along the circumferential direction, and the input magnetic gear including a plurality of magnets fixedly mounted in the mounting grooves.

5. The joint module according to claim 4, characterized in that: The magnetic gear assembly also includes a battery and a control board arranged in the cavity, which are electrically connected to the motor respectively.

6. The joint module according to claim 3, characterized in that: A plurality of mounting grooves are evenly arranged along the circumferential direction on the lower surface of the upper cover, and a plurality of modulation blocks are fixedly installed in the mounting grooves accordingly; a plurality of mounting grooves are evenly arranged along the circumferential direction on the lower surface of the first connecting plate, and the input magnetic gear includes a plurality of magnets fixedly installed in the mounting grooves accordingly.

7. The joint module according to claim 3, characterized in that: A blind hole is provided on the upper surface of the upper cover, a bearing is embedded in the blind hole, and the first connecting plate is provided with a stepped through hole for installing the flange shaft. The size of the flange shaft is adapted to the bearing to form a rotating pair when the two joint modules are connected.

8. The joint module according to claim 3, characterized in that: The lower surface of the base is provided with a mounting hole for mounting a shaft sleeve, and the second connecting plate is provided with a mounting hole for mounting a rotating shaft. The size of the shaft sleeve is adapted to the rotating shaft to form a revolute pair when the two joint modules are connected.

9. A bionic robotic fish, characterized in that: The invention comprises at least two joint modules as described in any one of claims 1 to 8, wherein the two joint modules realize joint connection by forming a rotating pair with rotating parts installed on the upper and lower sides of the shell of one joint module and the first connecting plate and the second connecting plate of the other joint module respectively, and realize joint movement by driving the output magnetic gear in the other joint module to rotate through the input magnetic gear in one joint module.

10. The bionic robotic fish according to claim 9, characterized in that: One of the joint modules does not have an input magnetic gear and a modulation block set in a waterproof sealed space.

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