CN114571498A

CN114571498A - Sealed rotary servo joint for underwater robot

Info

Publication number: CN114571498A
Application number: CN202210401677.0A
Authority: CN
Inventors: 丑武胜; 康松; 孟令达
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2022-04-18
Filing date: 2022-04-18
Publication date: 2022-06-03
Anticipated expiration: 2042-04-18
Also published as: CN114571498B

Abstract

The invention discloses a sealed rotary servo joint for an underwater robot, and belongs to the technical field of underwater robots. The invention structurally arranges an outer magnet assembly outside a waterproof sleeve, an inner magnet assembly inside the waterproof sleeve, the inner magnet assembly is coaxially connected with a power device in a transmission way, the power device is arranged on a motor bracket, the motor bracket is hermetically connected with the bottom of the waterproof sleeve, and the outer magnet assembly, the waterproof sleeve and the inner magnet assembly are coaxially arranged. When the magnetic coupling type motor is used, a motor support and the waterproof sleeve form a closed space, the power device drives the inner magnet assembly to rotate in the waterproof sleeve, and the outer magnet assembly and the inner magnet assembly transmit torque through a magnetic coupling effect. The invention has good waterproof performance and stable and reliable structure, can realize the output of joint torque of 10 Nm magnitude order under the high water pressure environment on the premise of ensuring the motion precision, and provides a reliable solution for the arm operation of an underwater robot, particularly an underwater machine based on a rotary joint.

Description

Sealed rotary servo joint for underwater robot

Technical Field

The embodiment of the invention relates to the technical field of underwater robots, in particular to a sealed rotary servo joint for an underwater robot.

Background

The boundless sea decipies of wide range reserves extremely abundant oil and gas resources, mineral resources, biological resources and the like. However, the marine environment, particularly the deep sea environment, is very harsh, and people cannot perform underwater operation for a long time and efficiently in the high-pressure, low-temperature, dark and anoxic environments for a while. In recent years, underwater operation robots have become an effective way to perform underwater operations in place of humans. Different from land robots, the underwater robot has complex and changeable working environment, and the design difficulty of the underwater robot, particularly a driving joint, is increased.

Conventional underwater robot driving joints can be broadly classified into hydraulic cylinder driving type or motor driving type. The motor-driven joint is sealed underwater by mechanical sealing elements such as O-rings, Gla-rings and the like. When facing pollution of underwater silt, grease and the like and complex and changeable water environments of high pressure, high salinity and the like, the mechanical dynamic sealing mechanical arm joint has the defects of complex structure, high manufacturing precision, low reliability and short service life. In addition, the power loss caused by friction is not negligible. Besides the above disadvantages, the hydraulic cylinder driven mechanical arm is difficult to measure and feed back the joint angle, and is easy to cause the creeping phenomenon of sudden and sudden adhesion, and has great adverse effects on the precision and the like of the underwater mechanical arm. Besides, hydraulic oil is easy to leak, so that the water environment is polluted. In addition, as the sealing elements wear and age, hydraulic oil leakage may be exacerbated.

Therefore, how to design a novel simple structure, reliable and stable, easy to maintain has good waterproof performance, has accurate motion control and high load moment of torsion output's underwater robot joint concurrently becomes the technical problem that technical staff in this field had a urgent need to solve.

Disclosure of Invention

Therefore, the invention provides a sealed rotary servo joint for an underwater robot, and aims to solve the problems that in the prior art, the structure of a mechanical arm is complex, the cost is high and the later maintenance is not easy to realize due to the fact that the traditional joint sealing technology is not in place. Compared with the existing underwater robot joint, the rotary joint has the advantages of simple structure and excellent waterproof performance, can transmit joint torque of 10 Nm order of magnitude by adopting servo closed-loop control based on an encoder, can be used in an underwater operation environment with high-precision position closed-loop control, and has important economic benefit and social value for promoting the development and application of the underwater robot.

In order to achieve the above purpose, the invention provides the following technical scheme:

the invention discloses a sealed rotary servo joint facing an underwater robot, which comprises an outer magnet assembly, a waterproof sleeve, an inner magnet assembly, a power device and a motor support, wherein the outer magnet assembly is arranged on the outer side of the waterproof sleeve, the inner magnet assembly is arranged on the inner side of the waterproof sleeve, the inner magnet assembly is coaxially connected with the power device in a transmission manner, the power device is arranged on the motor support, the motor support is in threaded connection with the bottom of the waterproof sleeve in a sealing manner, and the outer magnet assembly, the waterproof sleeve and the inner magnet assembly are coaxially arranged. And the outer side of the inner magnet assembly and the inner side of the outer magnet assembly are circumferentially and uniformly distributed with strip-shaped neodymium-iron-boron magnetic steel.

Further, interior magnet subassembly includes transmission flange, interior magnetic sleeve, inner bearing and zero-bit magnet seat, power device is connected with transmission flange coaxial drive, the side of transmission flange is fixed with interior magnetic sleeve upper end spiro union, interior magnetic sleeve installs the inner bearing in the inner wall, zero-bit magnet seat is installed to interior magnetic sleeve lower extreme, and the fixed zero-bit magnet that is provided with on the zero-bit magnet seat.

Furthermore, the waterproof sleeve comprises a sealing flange, a magnetic conduction sealing cylinder, a bearing cover and a fixed shaft, the outer ring of the inner bearing is abutted against the magnetic conduction sealing cylinder, the bottom of the magnetic conduction sealing cylinder is integrally connected with the sealing flange, the top of the magnetic conduction sealing cylinder is screwed and fixed with the bearing cover, and the fixed shaft is arranged at the center of the bearing cover.

Furthermore, power device includes the reduction gear, has brush direct current motor and incremental encoder, the transmission flange cover is established on the output shaft of reduction gear, the input shaft of reduction gear with brush direct current motor coaxial drive is connected, brush direct current motor's tip is installed incremental encoder.

Further, the motor support comprises a support barrel, a dry spring tube seat, a sealing bottom plate and a piercing bolt, the speed reducer is installed at one end of the support barrel, the support barrel is fixedly connected with the dry spring tube seat in a threaded mode, the other end of the support barrel is integrally connected with the sealing bottom plate, the sealing bottom plate is fixedly connected with a sealing flange in a threaded mode in a sealing mode, and the piercing bolt is connected to the sealing bottom plate in a threaded mode.

Further, interior magnetic sleeve includes rotatory steel ring, interior permanent magnetism strip, fixed steelframe and connection screw, the outer lane of inner bearing is fixed to be set up on rotatory steel ring, rotatory steel ring interference fit is in the bottom of steelframe, the outer wall circumference of fixed steelframe evenly is provided with a plurality of recesses parallel with the generating line, arbitrary one the recess all imbeds and has an interior permanent magnetism strip, fixed steelframe top is provided with the connection screw of a plurality of fixed bearing lid.

Furthermore, the outer magnet assembly comprises a bearing outer end cover, an outer bearing, an outer magnet sleeve and outer permanent magnet strips, the bearing cover is located in the center of the bearing outer end cover, the bearing outer end cover is fixedly connected with the outer magnet sleeve in a threaded mode, a plurality of outer permanent magnet strips parallel to the bus are arranged on the inner wall of the outer magnet sleeve in the circumferential direction, the outer permanent magnet strips are connected with the inner permanent magnet strips in a magnetic suction mode, the inner ring of the outer bearing is sleeved on the magnetic conduction sealing cylinder, and the outer ring of the outer bearing abuts against the outer magnet sleeve.

Furthermore, the outer permanent magnet strip and the inner permanent magnet strip are both made of neodymium iron boron permanent magnets.

Furthermore, the magnetic conduction sealing cylinder is made of austenitic stainless steel.

Furthermore, a reed pipe is arranged on the reed pipe seat and is electrically connected with the incremental encoder.

The invention has the following advantages:

1. the technical scheme mainly aims to solve the problems of easy leakage, low reliability, complex structure, high cost and the like of the existing underwater robot joint, a waterproof closed space is formed by utilizing a magnetic conduction sealing cylinder and a sealing bottom plate, neodymium iron boron permanent magnets are arranged inside and outside the magnetic conduction sealing cylinder, and torque is output through magnetic field coupling, so that the underwater robot joint based on magnetic coupling is developed. The waterproof performance is excellent, and the waterproof performance can reach the waterproof experimental grade standard of IPX 8 grade or above.

2. The invention adopts a mode of circumferentially and uniformly distributing the multi-stage magnets to increase the magnetic force between the inner magnetic steel and the outer magnetic steel, can realize the output of joint torque of 10 Nm magnitude order under the high water pressure environment on the premise of ensuring the joint movement precision, and has the advantages of higher reliability, longer service life, simple structure, easy maintenance, stability and reliability.

3. The invention adopts the reed switch as the zero position trigger switch of the incremental encoder, and plays a role in calibrating the absolute zero position of the rotary robot joint. The sealed rotary joint can be applied to high-precision closed-loop control of the underwater robot.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.

The structures, ratios, sizes, and the like shown in the present specification are only used for matching with the contents disclosed in the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions that the present invention can be implemented, so that the present invention has no technical significance, and any structural modifications, changes in the ratio relationship, or adjustments of the sizes, without affecting the effects and the achievable by the present invention, should still fall within the range that the technical contents disclosed in the present invention can cover.

FIG. 1 is an exploded view of a sealed rotary servo joint for an underwater robot according to the present invention;

FIG. 2 is a perspective view of a motor bracket of a sealed rotary servo joint for an underwater robot according to the present invention;

FIG. 3 is a perspective view of a waterproof sleeve for a sealed rotary servo joint of an underwater robot according to the present invention;

FIG. 4 is a perspective view of an outer magnet assembly of a sealed rotary servo joint for an underwater robot according to the present invention;

FIG. 5 is a perspective view of an inner magnetic sleeve of a sealed rotary servo joint for an underwater robot according to the present invention;

FIG. 6 is a perspective view of the inner magnet assembly of the sealed rotary servo joint for the underwater robot according to the present invention;

FIG. 7 is a perspective view of a power plant facing a sealed rotary servo joint of an underwater robot according to the present invention;

FIG. 8 is a perspective view of a sealed rotary servo joint for an underwater robot according to the present invention;

in the figure: 1 an outer magnet assembly; 11 bearing outer end covers; 12 an outer bearing; 13 an outer magnet sleeve; 14 outer permanent magnetic strips; 2, a waterproof sleeve; 21 sealing the flange; 22 a magnetically conductive sealing cylinder; 23 bearing caps; 24, fixing the shaft; 3 an inner magnet assembly; 31 a drive flange; 32 an internal magnetic sleeve; 321 rotating the steel ring; 322 inner permanent magnetic strips; 323 fixing the steel frame; 324 is connected with the screw hole; 33 an inner bearing; 34 a zero magnet mount; 35 a zero position magnet; 4, a power device; 41 a speed reducer; 42 brush DC motor; a 43 incremental encoder; 5, a motor bracket; 51 a support cylinder; 52 a dry reed pipe base; 53 sealing the bottom plate; 54 a feedthrough bolt; 55 dry reed pipes.

Detailed Description

The present invention is described in terms of particular embodiments, other advantages and features of the invention will become apparent to those skilled in the art from the following disclosure, and it is to be understood that the described embodiments are merely exemplary of the invention and that it is not intended to limit the invention to the particular embodiments disclosed. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1-8, the invention discloses a sealed rotary servo joint facing an underwater robot, which comprises an outer magnet assembly 1, a waterproof sleeve 2, an inner magnet assembly 3, a power device 4 and a motor support 5, wherein the outer magnet assembly 1 is arranged on the outer side of the waterproof sleeve 2, the inner magnet assembly 3 is arranged on the inner side of the waterproof sleeve 2, and the waterproof sleeve 2 can be matched with the motor support 5 to directly and hermetically wrap the inner magnet assembly 3, the power device 4 and the motor support 5, so that the waterproof test grade standard above IPX 8 grade can be achieved. Interior magnet subassembly 3 is connected with the coaxial transmission of power device 4, and outer magnet subassembly 1, waterproof sleeve 2 and interior magnet subassembly 3 are coaxial to be arranged to it is rotatory to drive interior magnet subassembly 3, because interior magnet subassembly 3 passes waterproof sleeve 2 magnetic attraction with outer magnet subassembly 1, thereby drives outer magnet subassembly 1 and rotates, and outer magnet subassembly 1 directly links to each other with the load, thereby realizes the drive load from this, accomplishes the technical purpose of joint activity. The power device 4 is installed on the motor support 5, the motor support 5 is in threaded connection with the bottom of the waterproof sleeve 2, a rubber sealing ring is arranged at the joint, and long-time water immersion test or continuous diving test can be prohibited. In addition, the technical scheme mainly outputs the torque in a magnetic coupling mode on the principle design, so that the problem of mechanical friction does not exist, the joint transmission efficiency is higher than that of the traditional underwater joint, and the stability and the reliability of the output torque can be ensured.

According to an embodiment of the present invention, the inner magnet assembly 3 includes a transmission flange 31, an inner magnetic sleeve 32, an inner bearing 33, a zero-position magnet holder 34 and a zero-position magnet 35, as shown in fig. 5 and 6, an output shaft of the speed reducer 41 is directly inserted into the transmission flange 31, and transmits torque through a key, so that the power device 4 is coaxially connected with the transmission flange 31 in a transmission manner, and a side surface of the transmission flange 31 is fixed to an upper end of the inner magnetic sleeve 32 in a threaded manner, thereby driving the inner magnetic sleeve 32 to rotate. An inner bearing 33 is installed on the inner wall of the inner magnetic sleeve 32, a zero-position magnet seat 34 is installed at the lower end of the inner magnetic sleeve 32, a single zero-position magnet 35 is installed on the zero-position magnet seat 34, when the zero-position magnet 35 moves to be close to the reed pipe 55, the reed pipe 55 is triggered to generate an induction signal, the incremental encoder 43 receives the signal to be set to zero, and then the position of the mechanical arm joint is set to zero. Thereby controlling the rotational null position of the load.

According to an embodiment of the present invention, the waterproof sleeve 2 includes a sealing flange 21, a magnetic conductive sealing cylinder 22, a bearing cover 23 and a fixed shaft 24, an outer ring of the inner bearing 33 abuts against the magnetic conductive sealing cylinder 22, a bottom of the magnetic conductive sealing cylinder 22 is integrally connected to the sealing flange 21, a top of the magnetic conductive sealing cylinder 22 is screwed to the bearing cover 23, the fixed shaft 24 is disposed at a center of the bearing cover 23, the fixed shaft 24 serves as a rotation center of a load to perform a positioning function, and the incremental encoder 43 is used for transmitting a position signal. Because the joint of the technical scheme adopts the incremental encoder 43, the reed pipe seat 52 is provided with the reed pipe 55 as a zero position trigger element. The zero-position magnet seat 34 is provided with a zero-position magnet 35, the zero-position magnet 35 is close to the reed pipe 55 to act to generate an induction signal, and the incremental encoder 43 is set to be zero. Can separate power device 4's core part (reduction gear 41, brush DC motor 42 and incremental encoder 43) and external environment completely through this structure, prevent impurity such as steam, dust from invading, easy later maintenance to make underwater joint cost reduction, realize its lightweight, long service life's technical goal.

According to an embodiment of the present invention, the power device 4 includes a speed reducer 41, a brushed dc motor 42 and an incremental encoder 43, and the transmission flange 31 is sleeved on an output shaft of the speed reducer 41 to improve torque output and reduce inertia of a load. The speed reducer 41 described in this embodiment is a precision speed reducer such as a harmonic gear speed reducer, a cycloidal pin gear planetary speed reducer, an RV speed reducer, a precision planetary speed reducer, and a filter gear speed reducer, and has the characteristics of short transmission chain, small volume, large power, light weight, and easy control. The input shaft of the speed reducer 41 is in coaxial transmission connection with the brush direct current motor 42, the incremental encoder 43 is mounted at the end of the brush direct current motor 42, the incremental encoder 43 is electrically connected with the reed pipe 55 on the reed pipe seat 52, and therefore an electric signal is sent to the incremental encoder 43 through the reed pipe 55, and the zero position of the joint is sensed.

According to one embodiment of the present invention, the motor support 5 includes a support cylinder 51, a reed pipe seat 52, a sealing bottom plate 53 and a piercing bolt 54, the reducer 41 is installed at one end of the support cylinder 51, the support cylinder 51 is screwed and fixed with the reed pipe seat 52, the other end of the support cylinder 51 is integrally connected with the sealing bottom plate 53 to improve the mechanical strength of the support cylinder 51, the sealing bottom plate 53 is screwed and fixed with the sealing flange 21, the sealing grade is above IPX7, the sealing bottom plate 53 is screwed and connected with the piercing bolt 54, the piercing bolt 54 is a hollow bolt, the sealing and fixing is realized by screwing a hollow nut, the reed pipe 55 installed on the reed pipe seat 52, the power line and the data transmission line required by the brushed dc motor 42 and the incremental encoder 43 are all connected with the outside through the piercing bolt 54, the reed pipe 55 is installed on the reed pipe seat 52, when the zero-position magnet 35 installed on the zero-position magnet seat 34 is close to the reed pipe 55, under the action of magnetic force lines of the magnetic field, the two reeds in the tube are magnetized to attract and contact with each other, and the reeds are attracted together to enable the circuits connected with the nodes to be communicated. After the external magnetic force disappears, the two reeds are separated due to the elasticity of the two reeds, the circuit is disconnected, a single zero-position magnet 35 is installed on the zero-position magnet seat 34, when the zero-position magnet seat 34 rotates to be close to the reed pipe 55, the reed pipe reeds are triggered, the incremental encoder 43 is set to be zero by sensing the pulse current, and then the position is set to be the zero position of the rotary joint. The incremental encoder 43 is multiplied by the reduction ratio of the reducer 41 to derive the angle of rotation of the outer magnet sleeve 13 and the corresponding load, thereby providing achievable advantages for closed-loop control of the joint.

According to a specific embodiment provided by the present invention, the inner magnetic sleeve 32 includes a rotating steel ring 321, an inner permanent magnetic strip 322, a fixed steel frame 323, and a connecting screw hole 324, the outer ring of the inner bearing 33 is fixedly disposed on the rotating steel ring 321, and the rotating steel ring 321 is welded at the bottom of the fixed steel frame 323, so that a gap exists between the rotating steel ring 321 and the magnetic conductive sealing cylinder 22, and abrasion between the rotating steel ring 321 and the magnetic conductive sealing cylinder 22 is avoided. The outer wall of the fixed steel frame 323 is uniformly provided with a plurality of grooves parallel to the bus, as shown in fig. 6, any one of the grooves is embedded with an inner permanent magnet strip 322, and the inner permanent magnet strip 322 is fixed and then sealed by glue, so that the problem that the inner permanent magnet strip 322 falls off is prevented. The top of the fixed steel frame 323 is provided with a plurality of connecting screw holes 324 for fixing the bearing cover 23, so that the bearing cover 23 can drive the fixed steel frame 323 to rotate.

According to a specific embodiment provided by the present invention, the outer magnet assembly 1 includes a bearing outer end cap 11, an outer bearing 12, an outer magnet sleeve 13 and outer permanent magnet bars 14, a bearing cap 23 is located at the center of the bearing outer end cap 11, and the bearing cap 23 mainly serves to improve the connection strength of the dead axle 24. The bearing outer end cover 11 is fixed with the outer magnet sleeve 13 in a threaded mode, and the bearing outer end cover 11 is used for connecting a load with the outer magnet sleeve 13, so that the load is driven to rotate through the outer magnet sleeve 13. The inner wall of the outer magnet sleeve 13 is provided with a plurality of outer permanent magnet strips 14 parallel to the bus, the outer permanent magnet strips 14 are magnetically attracted with the inner permanent magnet strips 322, so that torque is transmitted through magnetic coupling, the problem of the aging life of a sealing ring is not required to be considered in the sealing process of a traditional rubber ring, and the outer magnet sleeve has the advantages of simple structure, small design difficulty and good sealing effect. The magnetic field can be sleeved on the magnetic conduction sealing cylinder 22 through the inner ring of the outer bearing 12 of the magnetic conduction sealing cylinder 22, the outer ring of the outer bearing 12 is abutted against the outer magnet sleeve 13, and therefore the outer bearing 12 and the inner bearing 33 support the two ends of the magnetic conduction sealing cylinder 22, and the outer magnet sleeve 13 and the inner magnet sleeve 32 are enabled to be stably driven.

According to an embodiment of the present invention, the magnetic conductive sealing cylinder 22 is made of austenitic stainless steel with excellent magnetic permeability, which can ensure the magnetic attraction between the inner and outer magnetic strips. Furthermore, electrochemical protection can be used to improve the seawater corrosion resistance of the magnetically conductive sealing cylinder 22.

The application process of the embodiment of the invention is as follows:

the invention discloses a sealed rotary servo joint facing an underwater robot, wherein when the mechanism runs, firstly, a brush direct current motor 42 drives an input shaft of a speed reducer 41 to rotate, an output shaft of the speed reducer 41 drives an inner magnetic sleeve 32 to rotate through a bearing cover 23, the inner magnetic sleeve 32 is in magnetic attraction connection with an outer magnetic sleeve 13 so as to drive the outer magnetic sleeve 13 to rotate, the outer magnetic sleeve 13 drives a load to rotate, in the rotating process of the inner magnetic sleeve 32, a magnetic conduction sealing sleeve 22 is in threaded connection and fixed with a sealing bottom plate 53 in a sealing mode, so that water vapor cannot be in contact with electronic equipment such as the inner magnetic sleeve 32 and the brush direct current motor 42, the zero position of a coder is set through the action of a zero position magnet 35 and a reed pipe 55, and an incremental coder 43 is used for calculating the rotating position of the load so as to realize closed-loop control.

Although the invention has been described in detail above with reference to a general description and specific examples, it will be apparent to one skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. A sealed rotary servo joint facing an underwater robot is characterized by comprising an outer magnet assembly (1), a waterproof sleeve (2), an inner magnet assembly (3), a power device (4) and a motor support (5), the outer magnet assembly (1) is arranged on the outer side of the waterproof sleeve (2), the inner magnet assembly (3) is arranged on the inner side of the waterproof sleeve (2), the inner magnet assembly (3) is in coaxial transmission connection with the power device (4), the power device (4) is arranged on the motor support (5), the motor support (5) is in threaded connection with the bottom of the waterproof sleeve (2) in a sealing way, the outer magnet assembly (1), the waterproof sleeve (2) and the inner magnet assembly (3) are coaxially arranged, and strip-shaped neodymium iron boron magnetic steels are uniformly distributed on the outer side of the inner magnet assembly (3) and the inner side of the outer magnet assembly (1) in the circumferential direction.

2. The sealed rotary servo joint facing the underwater robot is characterized in that the inner magnet assembly (3) comprises a transmission flange (31), an inner magnet sleeve (32), an inner bearing (33) and a zero magnet seat (34), the power device (4) is in coaxial transmission connection with the transmission flange (31), the side face of the transmission flange (31) is in threaded connection with the upper end of the inner magnet sleeve (32) and fixed to the upper end of the inner magnet sleeve (32), the inner bearing (33) is installed on the inner wall of the inner magnet sleeve (32), the zero magnet seat (34) is installed at the lower end of the inner magnet sleeve (32), and the zero magnet (35) is fixedly arranged on the zero magnet seat (34).

3. The sealed rotary servo joint facing the underwater robot as claimed in claim 2, wherein the waterproof sleeve (2) comprises a sealing flange (21), a magnetic conductive sealing cylinder (22), a bearing cover (23) and a fixed shaft (24), the outer ring of the inner bearing (33) abuts against the magnetic conductive sealing cylinder (22), the bottom of the magnetic conductive sealing cylinder (22) is integrally connected with the sealing flange (21), the top of the magnetic conductive sealing cylinder (22) is fixed with the bearing cover (23) in a threaded manner, and the fixed shaft (24) is arranged at the center of the bearing cover (23).

4. The sealed rotary servo joint facing the underwater robot is characterized in that the power device (4) comprises a speed reducer (41), a brush direct current motor (42) and an incremental encoder (43), the transmission flange (31) is sleeved on an output shaft of the speed reducer (41), an input shaft of the speed reducer (41) is in coaxial transmission connection with the brush direct current motor (42), and the incremental encoder (43) is installed at the end part of the brush direct current motor (42).

5. The sealed rotary servo joint facing the underwater robot of claim 4, wherein the motor support (5) comprises a support barrel (51), a dry reed pipe seat (52), a sealing bottom plate (53) and a piercing bolt (54), the speed reducer (41) is installed at one end of the support barrel (51), the support barrel (51) is fixed with the dry reed pipe seat (52) in a threaded manner, the other end of the support barrel (51) is integrally connected with the sealing bottom plate (53), the sealing bottom plate (53) is fixed with the sealing flange (21) in a threaded manner in a sealing manner, and the piercing bolt (54) is connected with the sealing bottom plate (53) in a threaded manner.

6. The sealed rotary servo joint facing the underwater robot as claimed in claim 5, wherein the inner magnetic sleeve (32) comprises a rotary steel ring (321), inner permanent magnetic strips (322), a fixed steel frame (323) and connecting screw holes (324), the outer ring of the inner bearing (33) is fixedly arranged on the rotary steel ring (321), the rotary steel ring (321) is assembled at the bottom of the steel frame (323) in an interference manner, a plurality of grooves parallel to a bus are uniformly arranged on the outer wall of the fixed steel frame (323) in the circumferential direction, one inner permanent magnetic strip (322) is embedded in any one of the grooves, and the connecting screw holes (324) of a plurality of fixed bearing covers (23) are arranged at the top of the fixed steel frame (323).

7. The sealed rotary servo joint facing the underwater robot as claimed in claim 6, wherein the outer magnet assembly (1) comprises a bearing outer end cover (11), an outer bearing (12), an outer magnet sleeve (13) and outer permanent magnet strips (14), the bearing cover (23) is located at the center of the bearing outer end cover (11), the bearing outer end cover (11) is fixed to the outer magnet sleeve (13) in a threaded manner, a plurality of outer permanent magnet strips (14) parallel to a bus are arranged on the inner wall of the outer magnet sleeve (13) in the circumferential direction, the outer permanent magnet strips (14) are connected with the inner permanent magnet strips (322) in a magnetic attraction manner, the inner ring of the outer bearing (12) is sleeved on the magnetic conductive sealing cylinder (22), and the outer ring of the outer bearing (12) abuts against the outer magnet sleeve (13).

8. The sealed rotary servo joint for the underwater robot as claimed in claim 7, wherein the outer permanent magnet strips (14) and the inner permanent magnet strips (322) are made of neodymium iron boron permanent magnets.

9. The sealed rotary servo joint for underwater robots according to claim 8, characterized in that the magnetically conductive sealing cylinder (22) is made of austenitic stainless steel.

10. A sealed rotary servo joint towards a underwater robot according to claim 5, characterized in that the reed pipe socket (52) is provided with a reed pipe (55).