CN114851240A

CN114851240A - Joint unit and robot arm

Info

Publication number: CN114851240A
Application number: CN202210364165.1A
Authority: CN
Inventors: 魏洪兴; 崔元洋; 张海豹; 靳宇; 牟联树; 赵永利
Original assignee: Aubo Beijing Robotics Technology Co ltd
Current assignee: Aubo Beijing Robotics Technology Co ltd
Priority date: 2022-04-07
Filing date: 2022-04-07
Publication date: 2022-08-05

Abstract

The joint unit comprises a machine shell, a main shaft, a motor assembly and a harmonic reducer. The housing includes a cavity. The cavity forms a cavity opening on the machine shell. The main shaft is rotatably arranged in the cavity along the axis of the main shaft, and one end of the main shaft is positioned at the cavity opening. The stator of the motor component is fixed in the cavity and arranged around the periphery of the main shaft. The stator can drive the rotor to rotate around the outer circumference of the main shaft. The harmonic reducer comprises a wave generator, a steel wheel and a flexible wheel. The joint unit has the advantages of compact overall structure, small volume, light weight, high structural strength, simple structure and low cost. Meanwhile, the connection strength between the main shaft and the flexible gear can be effectively ensured, and the flange is convenient for external structure connection.

Description

Joint unit and robot arm

Technical Field

The invention relates to a joint unit which can be used in the fields of robots, automatic processing devices, processing systems, industrial production and processing and can provide power for mechanical arms, processing arms or joints to meet the driving requirements of the mechanical arms. The invention also relates to a mechanical arm with the joint unit.

Background

The robot joint module adopts independent harmonic reducer to slow down more, because harmonic reducer is independent of robot joint spare, its overall structure is complicated, not enough simplify and volume and weight are big, and structural strength is low, can't guarantee long-term and stable use, and manufacturing cost is high, is unfavorable for batch production, therefore current structure is not suitable for the application occasion of arm.

Disclosure of Invention

The invention aims to provide a joint unit which is compact in overall structure, small in size, light in weight, simple in structure and low in cost, and can effectively improve the structural strength of a robot joint module.

Another object of the present invention is to provide a robot arm, which has high structural strength, easy assembly, simple structure and convenient application.

In one aspect of the invention, a joint unit is provided, comprising a housing, a spindle, a motor assembly, and a harmonic reducer. Wherein, the casing includes the cavity. The cavity forms a cavity opening on the machine shell. The main shaft is rotatably arranged in the cavity along the axis of the main shaft, and one end of the main shaft is positioned at the cavity opening.

The motor assembly is arranged in the cavity. A rotor in the motor assembly is capable of outputting torque for rotation about a main shaft.

The harmonic reducer comprises a wave generator, a steel wheel and a flexible wheel. The wave generator is connected to the rotor and rotates with the rotor around the outer circumference of the main shaft. The steel wheel is fixed in the cavity and is coaxial in the assembly of main shaft and has the interior drive hole towards the main shaft. The inner wall of the inner driving hole is provided with meshing teeth around the axis of the inner driving hole. The flexible gear is fixedly connected to the main shaft, and gear teeth are uniformly distributed on the outer surface of the flexible gear. The flexible gear is coaxially assembled on the outer periphery of the wave generator and can be driven by the wave generator to enable gear teeth at two ends of the same radial direction to be meshed with the meshing teeth, so that the rotating speed of the flexible gear is lower than that of the wave generator.

The output flange is assembled with one end of the main shaft positioned at the cavity opening through a flange hole. One end of the output flange facing the cavity is connected with the flexible gear.

In another embodiment of the joint assembly of the present invention, the end of the output flange defining the flange aperture includes an outer flange surface. The extension direction of the outer flange surface is parallel to the axis of the main shaft. And a plurality of outer bearing grooves corresponding to the width of the bearing outer ring are formed on the cavity wall of the outer flange surface opposite to the cavity at intervals. The outer flange surface is assembled in the cavity through a ball bearing. The outer ring of the ball bearing is fixed in the outer bearing groove, and the two ball bearings are arranged along the extending direction of the outer flange surface.

In yet another embodiment of the joint assembly of the present invention, the joint assembly further comprises a sleeve shaft fixedly attached to the wave generator. The sleeve shaft and the main shaft are coaxially arranged and are arranged in the radial direction of the main shaft. The outer circumference of the sleeve shaft is connected with the rotor, so that the wave generator is connected with the rotor through the sleeve shaft.

The main shaft is rotatably connected with the sleeve shaft through a first rolling connecting piece, so that the sleeve shaft can rotate along the outer circumferential surface of the main shaft. One end of the main shaft, which is far away from the cavity opening, is connected with the machine shell through a second rolling connecting piece.

In another embodiment of the joint assembly of the present invention, the joint assembly further comprises a brake plate, an electromagnetic member, a stopper pin, and an elastic member. The brake plate has a rotation axis and the rotation axis is perpendicular to the plate surface of the brake plate. And a plurality of braking notches are formed on the plate surface of the braking plate around the rotating axis. The brake plate and the sleeve shaft are coaxially arranged. The electromagnetic part is fixed on the shell.

The limit pin is arranged on the shell in a sliding manner along the sliding direction. The sliding direction is perpendicular to the plate surface of the brake plate and can be positioned on the position of the brake notch. The limiting pin and the electromagnetic piece are arranged according to a set distance and can move from the braking position to the initial position when the electromagnetic piece is electrified. When the limiting pin is located at the braking position, the limiting pin covers the braking notch so as to brake the sleeve shaft connected with the braking plate. The elastic piece is connected with the limiting pin and continuously applies elastic force to the limiting pin to enable the limiting pin to be located at the braking position.

In another embodiment of the joint assembly of the present invention, the electromagnetic member has an extending direction and an inner hole is formed along the extending direction. One end of the limit pin is arranged in the inner hole in a sliding mode. The joint unit further includes: and the end cover covers the inner hole at the end far away from the brake plate. A spring hole is formed on the stopper pin in the extending direction of the stopper pin. The opening of the spring hole faces the arrangement direction of the electromagnetic piece. One end of the elastic piece is arranged in the spring hole, and the other end of the elastic piece is connected to the end cover.

In yet another embodiment of the joint assembly of the present invention, the joint assembly further comprises an optical encoder. The photoelectric encoder includes: code wheel and decoder. The code wheel is coaxially assembled on the sleeve shaft and a grating hole is formed on the disk surface. The decoding part is arranged on the main shaft and is provided with a photosensitive reading head which can be positioned in the extending direction of the grating hole. The decoding part can acquire the rotation angle information of the rotor thereof through the number information of the grating holes read by the photosensitive reading head.

In still another embodiment of the joint assembly of the present invention, the joint unit further includes: a magnetic encoded disk and a magnetic read head. Magnetic induction pieces are uniformly arranged on the outer circumference of the magnetic encoding disk. The magnetic coding disc is fixed on the outer flange surface and is positioned between the two ball bearings. The magnetic reading head is fixed on the inner wall of the cavity and is positioned in the direction facing the outer circumference of the magnetic encoding disk and can acquire the rotation angle information of the magnetic encoding disk.

In still another embodiment of the joint assembly of the present invention, the motor assembly includes: stator, rotor and motor drive. The stator is fixed in the cavity and is arranged around the periphery of the main shaft. The rotor is located between the stator and the main shaft and is arranged coaxially with the stator. The stator can drive the rotor to rotate around the outer circumference of the main shaft. The motor driving part can drive the rotor to rotate.

In another embodiment of the joint assembly of the present invention, the joint assembly further comprises a master control board. The master control board is arranged in the concave cavity and is provided with a master controller. The master controller has an input and an output.

The output end is connected with the driving end of the electromagnetic piece, and the driving end of the electromagnetic piece can be driven to lose power under a set condition so that the limiting pin is located at the braking position. And/or the output end is connected with the driving end of the decoding part, so that the decoding part acquires the rotation angle information of the rotor. The input end is connected with the acquisition end of the decoding piece and can obtain the rotation angle information of the rotor from the acquisition end of the decoding piece.

And/or the output end is connected with the driving end of the magnetic reading head so that the magnetic reading head acquires the rotation angle information of the magnetic encoding disk. The input end is connected with the acquisition end of the magnetic reading head and can obtain the rotation angle information of the magnetic encoding disk from the acquisition end of the magnetic reading head. The output end is connected with the driving end of the motor driving piece, and the motor driving information can be output to the driving end of the motor driving piece when the motor driving information is obtained, so that the rotor of the motor rotates.

In another aspect of the invention, a mechanical arm is also provided. The mechanical arm comprises a joint piece and a joint unit. The joint unit is connected to the main shaft of the joint member.

Drawings

Fig. 1 is a schematic diagram for explaining the structure of a joint unit.

Fig. 2 is a schematic diagram for explaining a partial structure of the joint unit.

Fig. 3 is a schematic diagram for explaining the structure of the stopper pin partial structure in the initial position in the joint unit.

Fig. 3a is a schematic structural view for explaining a local structure of the limit pin in the joint unit at a braking position.

Fig. 4 is a schematic view for explaining the structure of a brake pad portion in the joint unit.

Fig. 5 is a schematic view for explaining the structure of a joint unit in another embodiment.

Fig. 6 is a schematic bottom view for explaining a partial structure of the joint unit.

Detailed Description

In order to more clearly understand the technical features, objects and effects of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings, in which the same reference numerals indicate the same or structurally similar but functionally identical elements.

"exemplary" means "serving as an example, instance, or illustration" herein, and any illustration, embodiment, or steps described as "exemplary" herein should not be construed as a preferred or advantageous alternative.

For the sake of simplicity, the drawings only schematically show the parts relevant to the present exemplary embodiment, and they do not represent the actual structure and the true scale of the product.

In one aspect of the present invention, as shown in fig. 1, there is provided a joint unit including a housing 10, a spindle 20, a motor assembly, and a harmonic reducer. Wherein the cabinet 10 includes a cavity 11. The cavity 11 forms a cavity opening 12 in the housing 10. The main shaft 20 is rotatably disposed in the cavity 11 along an axis 21 thereof and has one end located at the cavity opening 12.

As shown in fig. 1, the motor assembly is disposed in the cavity 11. The rotor 32 in the motor assembly is capable of outputting torque for rotation about the main shaft 20.

As shown in fig. 1 and 2, the harmonic reducer includes a wave generator 41, a steel wheel 42, and a flexible wheel 43. The wave generator 41 is connected to the rotor 32 and rotates with the rotor 32 around the outer circumference of the main shaft 20. A steel wheel 42 is fixed to the cavity 11 and is fitted coaxially to the spindle 20 and has an inner driving hole 44 facing the spindle 20. The inner wall of the inner drive bore 44 is provided with meshing teeth about its axial centre. The flexible gear 43 is fixedly connected to the main shaft 20 and has gear teeth uniformly distributed on the outer surface. The flexible gear 43 is coaxially assembled on the outer circumference of the wave generator 41 and can be driven by the wave generator 41 to enable gear teeth at two ends of the same radial direction to be meshed with meshing teeth, so that the rotating speed of the flexible gear 43 is lower than that of the wave generator 41.

As shown in fig. 1 and 2, the output flange 24 is fitted to the end of the main shaft 20 at the port 12 through its flange hole. The end of the output flange 24 facing the cavity 11 is connected to the flexible gear 43, so that the flexible gear 43 is fixedly connected to the main shaft 20 through the output flange 24.

Therefore, the joint unit integrates the stator and the rotor of the motor and the harmonic reducer in the cavity, the rotor drives the wave generator to rotate, and the flexible gear outputs the torque after speed reduction through the main shaft. The flexspline and the spindle are supported inside the housing by an output flange. The joint piece is compact in structure, small in size, light in weight and high in integration, and the problems that the existing joint piece is loose in overall structure, large in size and weight and low in structural strength are solved. Meanwhile, the connection strength between the main shaft and the flexible gear can be effectively ensured, and the flange is convenient for external structure connection.

In yet another embodiment of the joint assembly of the present invention, as shown in fig. 5, the end of the output flange 24 defining the flange bore includes an outer flange surface 27. The outer flange face 27 extends parallel to the axis of the spindle 20. The cavity wall of the outer flange surface 27 opposite to the cavity 11 is provided with a plurality of outer bearing grooves 16 at intervals, and the width of the outer bearing grooves corresponds to that of the outer ring of the bearing. The outer flange face 27 is fitted into the cavity 11 by means of ball bearings.

As shown in fig. 5, the outer ring of the ball bearing is fixed in the outer bearing groove 16, and two ball bearings are provided along the extending direction of the outer flange surface 27. The ball bearing can preferably be a deep groove ball bearing, so that on the one hand, the fixation of the bearing itself is facilitated. On the other hand, the assembly of the bearing is facilitated. The outer flange face 27 is fitted into the cavity 11 by means of two

ball bearings

25, 26. Two ball bearings are arranged in the extension direction of the outer flange face 27. Therefore, the flange can be better fixed, and the rotation of the main shaft is more stable.

In yet another embodiment of the joint assembly of the present invention, as shown in fig. 1, the joint assembly further comprises a sleeve shaft 21 fixedly connected to the wave generator 41. The sleeve shaft 21 is disposed coaxially with the main shaft 20 and is disposed in a radial direction of the main shaft 20. The rotor 32 is coupled to the outer circumference of the sleeve shaft 21 such that the wave generator 41 is coupled to the rotor 32 through the sleeve shaft 21. So that the torque of the rotor driving to the wave generator is more stable. The sleeve shaft 21 and the main shaft 20 which are connected with the rotor output are coaxially arranged, and the main shaft is positioned in the sleeve shaft 21, so that the structure is compact while the transmission strength of the main shaft is ensured.

As shown in fig. 1, the main shaft 20 is rotatably connected to the sleeve shaft 21 via a first rolling connection 22, so that the sleeve shaft 21 can rotate along the outer circumferential surface of the main shaft 20. The first rolling connections 22 may be provided at both ends of the main shaft 20 in the extending direction of the main shaft 20, i.e., at two ends, to make the support of the main shaft 20 more stable. When the axial length of the main shaft 20 is long, the first rolling connection member 22 may be provided in plurality according to actual support requirements.

The end of the main shaft 20 remote from the bore 12 is connected to the housing 10 by a second roll connection 23. Thereby securing the supporting strength of the main shaft 20.

In another embodiment of the joint assembly according to the present invention, as shown in fig. 3 and fig. 3a, the joint assembly further comprises a brake plate 51, an electromagnetic member 52, a stopper pin 53 and an elastic member 54. The brake plate 51 has a pivot axis and the pivot axis is perpendicular to the plate surface of the brake plate 51. A plurality of detent notches 55 are provided in the plate surface of the detent plate 51 around the pivot axis. The brake plate 51 is disposed coaxially with the sleeve shaft 21. The electromagnetic member 52 is fixed to the casing 10.

As shown in fig. 3, fig. 3a, and fig. 4, the stopper pin 53 is slidably provided to the housing 10 in the sliding direction a 1. The sliding direction a1 is perpendicular to the plate surface of the brake plate 51 and can be located at the position of the brake notch 55. The stopper pin 53 and the solenoid 52 are provided at a set interval and can move from the braking position to the initial position (shown in fig. 3) when the solenoid 52 is energized. When the stopper pin 53 is located at the braking position (as shown in fig. 3 a), the stopper pin 53 is shielded in the braking notch 55 to brake the sleeve shaft connected to the braking plate 51. The elastic member 54 is connected to the stopper pin 53, and continuously applies an elastic force to the stopper pin 53 to position it at the detent position. The sleeve shaft is braked through the brake plate so as to brake the sleeve shaft and control the output torque of the joint unit.

In yet another embodiment of the joint assembly of the present invention, as shown in fig. 3 and 4, the electromagnetic member 52 has an extending direction and an inner hole 56 is opened along the extending direction. One end of the limit pin 53 is slidably disposed in the inner bore 56.

As shown in fig. 3 and 4, the joint unit further includes: and an end cap 13 covering the inner bore 56 at an end facing away from the brake plate 51. A spring hole is formed in the stopper pin 53 in the extending direction of the stopper pin 53. The opening of the spring hole faces the direction in which the electromagnetic member 52 is disposed. One end of the elastic member 54 is disposed in the spring hole, and the other end of the elastic member 54 is connected to the end cap 13. Thereby facilitating the replacement of the braking part through the end cover and saving the space in the cavity.

In yet another embodiment of the joint assembly of the present invention, as shown in fig. 5, a photoelectric encoder is further included. The photoelectric encoder includes: a code wheel 61 and a decoder 62. The code wheel 61 is coaxially fitted to the sleeve shaft 21 and a grating hole is formed on the disk surface. The decoder 62 is provided to the spindle 20 and has a photosensitive read head that can be positioned in the direction in which the grating holes extend. The decoding member 62 can acquire the rotation angle information of its rotor 32 from the information of the number of grating holes read by the photosensitive reading head. So that the rotational speed of the sleeve shaft 21, i.e., the rotor, can be obtained.

As shown in fig. 5, the joint unit further includes: a magnetic encoded disk 71 and a magnetic read head 72. Magnetic induction pieces are uniformly arranged on the outer periphery of the magnetic encoding disk 71. The magnetic encoding disk 71 is fixed to the outer flange face 27 and is located between the two ball bearings. The magnetic reading head 72 is fixed on the inner wall of the cavity 11 and located in the direction facing the outer circumference of the magnetic encoding disk 71 and can collect the rotation angle information of the magnetic encoding disk 71. A plurality of magnetic parts or areas are uniformly arranged on the outer circumferential surface of the magnetic encoding disk 71, when the flange 24 is driven by the spindle to rotate, the magnetic encoding disk 71 rotates along with the flange, and the magnetic reading head 72 of the magnetic encoding disk induces the magnetic parts or areas on the outer circumference of the magnetic encoding disk 71, so that the rotation angle, namely the speed of the spindle is obtained.

In yet another embodiment of the joint assembly of the present invention, as shown in fig. 1, the housing 10 has a housing extension direction B1. The cavity 11 is disposed along the cabinet extending direction B1. The housing 10 has a first end 14 and a second end 15 in its housing extension direction B1. The first end 14 defines the orifice 12.

As shown in fig. 5, the joint unit further comprises an outer cap 81 having an inner cavity 82. The outer cap 81 can cover the second end 15 and the inner cavity 82 can face the second end 15.

In one embodiment of the present invention, a motor assembly includes: a stator 31, a rotor 32 and a motor drive. The stator 31 is fixed in the cavity 11 and disposed around the outer circumference of the main shaft 20. The rotor 32 is located between the stator 31 and the main shaft 20 and is disposed coaxially with the stator 31. The stator 31 can drive the rotor 32 to rotate around the outer circumference of the main shaft 20. The motor drive can drive the rotor 32 to rotate. Thereby making the overall structure more compact.

In yet another embodiment of the joint assembly of the present invention, as shown in fig. 5, a master control board 91 is further included. The master control board 91 is disposed in the inner cavity 82 and has a master controller. The master controller has an input and an output.

The output end is connected with the driving end of the electromagnetic piece 52, and the driving end of the electromagnetic piece 52 can be driven to lose power under a set condition, so that the limit pin 53 is located at the braking position. And/or the output end is connected to the drive end of the decoding member 62 so that the decoding member 62 acquires the rotational angle information of the rotor 32. The input end is connected with the collecting end of the decoding part 62 and can obtain the rotation angle information of the rotor 32 from the collecting end of the decoding part 62.

And/or the output end is connected to the driving end of the magnetic reading head 72 so that the magnetic reading head 72 acquires the rotation angle information of the magnetic encoder disk 71. The input end is connected with the acquisition end of the magnetic reading head 72 and can obtain the rotation angle information of the magnetic encoding disk 71 from the acquisition end of the magnetic reading head 72. The output end is connected with the driving end of the motor driving piece, and can output the motor driving information to the driving end of the motor driving piece when the motor driving information is acquired, so that the rotor 32 of the motor rotates.

In another aspect of the present invention, as shown in fig. 6, a robot arm is also provided. The robot arm includes a joint member 92 and a joint unit 93 in the present invention. The joint unit 93 is connected to the main shaft 20 of the joint member by means of a flange 24.

It should be understood that although the present description has been described in terms of various embodiments, not every embodiment includes only individual features, which are described herein for clarity purposes only, and those skilled in the art will recognize that the embodiments described herein can be combined as a whole to form other embodiments as would be understood by those skilled in the art.

The above-listed detailed description is only a specific description of a possible embodiment of the present invention, and they are not intended to limit the scope of the present invention, and equivalent embodiments or modifications made without departing from the technical spirit of the present invention should be included in the scope of the present invention.

Claims

1. A joint unit, characterized by comprising,

a housing comprising a cavity; the cavity forms a cavity opening on the shell;

the main shaft is rotatably arranged in the cavity along the axis of the main shaft, and one end of the main shaft is positioned at the cavity opening;

a motor assembly disposed in the cavity; a rotor in the motor assembly is capable of outputting torque rotating around the main shaft; a harmonic reducer, comprising:

a wave generator connected to the rotor and rotating with the rotor around an outer circumference of the main shaft;

a steel wheel fixed to the cavity and coaxially assembled with the main shaft and having an inner driving hole facing the main shaft; the inner wall of the inner driving hole is provided with meshing teeth around the axis of the inner driving hole; and

the flexible gear is fixedly connected to the main shaft, and gear teeth are uniformly distributed on the outer surface of the flexible gear; the flexible gear is coaxially assembled on the outer periphery of the wave generator and can be driven by the wave generator to enable gear teeth at two ends of the flexible gear in the same radial direction to be meshed with the meshing teeth, so that the rotating speed of the flexible gear is lower than that of the wave generator;

the output flange is assembled with one end, located at the cavity opening, of the main shaft through a flange hole of the output flange; one end, facing the cavity, of the output flange is connected with the flexible gear.

2. The joint unit of claim 1,

one end of the output flange, which forms the flange hole, comprises an outer flange surface; the extending direction of the outer flange surface is parallel to the axis of the main shaft; a plurality of outer bearing grooves corresponding to the width of the bearing outer ring are formed in the cavity wall of the outer flange surface opposite to the cavity at intervals;

the outer flange surface is assembled in the cavity through a ball bearing; the outer ring of the ball bearing is fixed in the outer bearing groove, and the two ball bearings are arranged along the extending direction of the outer flange surface.

3. The joint unit of claim 2, further comprising,

a sleeve shaft fixedly connected to the wave generator; the sleeve shaft and the main shaft are coaxially arranged and are arranged in the radial direction of the main shaft; the outer circumference of the sleeve shaft is connected with the rotor, so that the wave generator is connected with the rotor through the sleeve shaft;

the main shaft and the sleeve shaft are rotatably connected through a first rolling connecting piece, so that the sleeve shaft can rotate along the outer circumferential surface of the main shaft;

and one end of the main shaft, which is far away from the cavity opening, is connected with the machine shell through a second rolling connecting piece.

4. The joint unit of claim 3, further comprising,

a brake plate having a rotational axis perpendicular to a plate surface of the brake plate; a plurality of braking notches are formed in the plate surface of the braking plate around the rotation axis; the brake plate and the sleeve shaft are coaxially arranged;

an electromagnetic member fixed to the case;

a limit pin slidably disposed on the housing along a sliding direction; the sliding direction is perpendicular to the plate surface of the brake plate and can be positioned on the position of the brake notch; the limiting pin and the electromagnetic piece are arranged according to a set distance and can move from a braking position to an initial position when the electromagnetic piece is electrified; when the limiting pin is located at the braking position, the limiting pin is shielded in the braking notch, so that the sleeve shaft connected with the braking plate is braked;

and the elastic piece is connected with the limiting pin and continuously applies elastic force to the limiting pin to enable the limiting pin to be located at the braking position.

5. The joint unit according to claim 3, wherein the electromagnetic member has an extending direction and an inner hole is opened along the extending direction; one end of the limiting pin is arranged in the inner hole in a sliding manner;

the joint unit further includes: the end cover covers an inner hole at one end deviating from the brake plate;

forming a spring hole on the limit pin along the extending direction of the limit pin; the hole opening of the spring hole faces the arrangement direction of the electromagnetic piece; one end of the elastic piece is arranged in the spring hole, and the other end of the elastic piece is connected to the end cover.

6. The joint unit of claim 3, further comprising,

an optical-to-electrical encoder, comprising:

a code wheel coaxially assembled to the sleeve shaft and having a grating hole formed on a disc surface; and

a decoding member provided to the spindle and having a photosensitive reading head that can be positioned in the direction in which the grating hole extends; the decoding part can acquire the rotation angle information of the rotor thereof through the number information of the grating holes read by the photosensitive reading head.

7. The joint unit of claim 6, further comprising:

the magnetic encoding disk is uniformly provided with magnetic induction pieces at the outer circumference; the magnetic coding disc is fixed on the outer flange surface and is positioned between the two ball bearings; and

the magnetic reading head is fixed on the inner wall of the cavity, is positioned in the direction facing the outer circumference of the magnetic coding disk and can collect the rotation angle information of the magnetic coding disk.

8. The joint unit according to claim 1 to 7, wherein the motor assembly comprises,

the stator is fixed in the cavity and arranged around the periphery of the main shaft; and

the rotor is positioned between the stator and the main shaft and is coaxially arranged with the stator; the stator can drive the output to rotate around the main shaft;

and the motor driving part is connected to the stator and can drive the rotor to rotate through the stator.

9. The joint unit of claim 8, further comprising,

the master control board is arranged in the concave cavity and is provided with a master controller; the master controller is provided with an input end and an output end;

the output end is connected with the driving end of the electromagnetic piece and can drive the driving end of the electromagnetic piece to lose power under a set condition so as to enable the limiting pin to be located at the braking position; and/or

The output end is connected with the driving end of the decoding piece so that the decoding piece can acquire the corner information of the rotor; the input end is connected with the acquisition end of the decoding piece and can acquire the rotation angle information of the rotor from the acquisition end of the decoding piece; and/or

The output end is connected with the driving end of the magnetic reading head so that the magnetic reading head can acquire the rotation angle information of the magnetic encoding disk; the input end is connected with the acquisition end of the magnetic reading head and can obtain the rotation angle information of the magnetic encoding disk from the acquisition end of the magnetic reading head;

the output end is connected with the driving end of the motor driving piece and can output motor driving information to the driving end of the motor driving piece when the motor driving information is obtained, so that a rotor of the motor rotates.

10. A robot arm, characterized in that it comprises,

a joint member; and

comprising a joint unit according to any one of claims 1 to 9; the joint unit is connected to the main shaft of the joint member.