Three-degree-of-freedom spherical joint motor module of integrated speed reducer

Abstract

The invention provides a three-degree-of-freedom spherical joint motor module of an integrated speed reducer, which belongs to the field of motors, and comprises a sphere, two groups of outer rotor permanent magnet direct current brushless motor modules of integrated single-stage speed reducers, a group of third axial magnetic flux permanent magnet direct current brushless motor modules for driving to rotate around an X / Y axis, and a group of third axial magnetic flux permanent magnet direct current brushless motor modules of integrated two-stage planetary speed reducers, the outer rotor permanent magnet direct current brushless motor modules of the two sets of integrated single-stage speed reducers integrally rotate around the Z axis, and the two sets of outer rotor permanent magnet direct current brushless motor modules are located on the outer surface of the ball body and are arranged in a 90-degree space mode. According to the ball joint motor, the two sets of outer rotor permanent magnet direct current brushless motor modules rotate around respective rotating shafts within a certain angle range, the movement range of the ball is remarkably expanded, the torque output capacity of the ball is improved, and the ball joint motor has the advantages of being compact in structure, high in space utilization rate and the like.

Description

Technical Field

[0001] The present invention belongs to the field of motors, and particularly relates to a three-degree-of-freedom spherical joint motor module integrated with a reducer. Background Art

[0002] For the shoulder joints and hip joints of humanoid robots, a three-rotational-degree-of-freedom joint motor system is composed of three independent joint motors. Although it can achieve large torque transmission, it has disadvantages such as low integration and large occupied space. As one of the branches of the three-degree-of-freedom system, the spherical joint motor system integrating three rotational degrees of freedom integrates three motors inside a sphere or a spherical shell to achieve three-rotational coordinate motion, and has become a research hotspot in recent years. The application fields involve vector vehicle lamps, radar seekers, neck joints, shoulder / hip joints and other fields.

[0003] In the application with the publication number CN115042224A and the invention name of a multi-degree-of-freedom spherical electric joint, a multi-degree-of-freedom spherical electric joint is disclosed. The working principle is that a connecting shaft is designed inside the third rotor located within the spherical frame, the output shaft passes through the cross connection of the first rotor and the second rotor, and the output shaft is connected to the connecting shaft through a universal joint, realizing the decoupling of the three-degree-of-freedom motion of the joint, with simple control and increased output torque. The characteristic is that the third rotor only drives the rotation of its own rotating shaft and is independent of the first rotor and the second rotor respectively. The disadvantages of this application are that the self-weights of the first motor, the second motor and the third motor inside the sphere lack effective bearing support, and the stator and rotor of each motor lack effective axial positioning and centering. It is a direct drive mode without a configured reducer, and the output torque is very small.

[0004] In the application with the publication number CN115229839A and the invention name of a three-degree-of-freedom spherical joint structure, a three-degree-of-freedom spherical joint structure is disclosed, which consists of three joint motors placed inside a spherical shell and independently controls the rotation around each axis. The characteristics are simple structure, small volume, large output torque, easy installation and maintenance, and a large three-degree-of-freedom motion range is achieved. The disadvantage of this application is that a large amount of space inside the sphere is not effectively utilized, and the entire sphere occupies a large volume. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a three-degree-of-freedom spherical joint motor module integrated with a reducer. To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A three-degree-of-freedom spherical joint motor module integrated with a reducer, comprising: a sphere, a first outer-rotor permanent magnet brushless DC motor module, a second outer-rotor permanent magnet brushless DC motor module, a third axial-flux permanent magnet brushless DC motor module, and a first housing assembly; wherein, the first outer-rotor permanent magnet brushless DC motor module integrates a first single-stage reducer, the second outer-rotor permanent magnet brushless DC motor module integrates a second single-stage reducer, and the third axial-flux permanent magnet brushless DC motor module integrates a two-stage planetary reducer;

[0007] Wherein, the first outer-rotor permanent magnet brushless DC motor module and the second outer-rotor permanent magnet brushless DC motor module are located on the outer surface of the sphere and are arranged at a 90-degree angle in space. The first outer-rotor permanent magnet brushless DC motor module, the second outer-rotor permanent magnet brushless DC motor module, and the sphere are placed in the first housing assembly. The first outer-rotor permanent magnet brushless DC motor module is used to realize the rotation of the sphere around the Y-axis; the second outer-rotor permanent magnet brushless DC motor module is used to realize the rotation of the sphere around the X-axis; the third axial-flux permanent magnet brushless DC motor module drives the first outer-rotor permanent magnet brushless DC motor module, the second outer-rotor permanent magnet brushless DC motor module, the sphere, and the first housing assembly to rotate as a whole around the Z-axis.

[0008] The present invention has the following beneficial effects:

[0009] The spherical joint motor of the present invention realizes the rotation of the outer-rotor permanent magnet brushless DC motor module integrated with the first single-stage reducer and the outer-rotor permanent magnet brushless DC motor module integrated with the second single-stage reducer around their respective rotation axes within a certain angle range (±40°), significantly expanding the movement range of the sphere and improving the output torque capacity of the sphere, and having the advantages of compact structure and high space utilization rate. Description of the Drawings

[0010] Figure 1 Is an axonometric view of a three-degree-of-freedom spherical joint motor module integrated with a reducer of the present invention;

[0011] Figure 2 Is a sectional view of a three-degree-of-freedom spherical joint motor module integrated with a reducer of the present invention;

[0012] Figure 3 Is a top view of a three-degree-of-freedom spherical joint motor module integrated with a reducer of the present invention;

[0013] Figure 4 Is a first structure diagram of the sphere wrapped by two groups of permanent magnet brushless DC motors of the integrated reducer of the present invention;

[0014] Figure 5 Is a second structure diagram of the sphere wrapped by two groups of permanent magnet brushless DC motors of the integrated reducer of the present invention;

[0015] Figure 6Explosion diagram 1 of the spherical joint motor module of the present invention;

[0016] Figure 7 Explosion diagram 2 of the spherical joint motor module of the present invention;

[0017] Figure 8 Structural diagram of an external rotor permanent magnet DC brushless motor with a pinion gear;

[0018] Figure 9 Structural diagram of a two-stage planetary reducer;

[0019] Figure 10 Cross-sectional view of an axial flux permanent magnet DC brushless motor module;

[0020] Figure 11 Structural diagram of the fully sunken sphere interior of the axial flux permanent magnet DC brushless motor of the present invention;

[0021] Figure 12 Structural diagram of the partially sunken sphere interior of the axial flux permanent magnet DC brushless motor of the present invention.

[0022] Wherein: 1 is the sphere, 1a is the first arc groove, 1b is the second arc groove, 1c is the third arc groove, and 1d is the fourth arc groove.

[0023] 100 is the first external rotor permanent magnet DC brushless motor module, 101 is the first guide wheel, 102 is the first pin shaft, 103 is the first guide rail, 104 is the first large gear, 110 is the first external rotor permanent magnet DC brushless motor, 105 is the first housing, 105a is the first boss wheel shaft, 105b is the first lead hole, 111 is the first rotor, 111a is the first rotor back iron, 111b is the first magnet, 112 is the first stator, 112a is the first stator winding, 112b is the first main shaft, 112c is the first stator core, and 113 is the first pinion gear.

[0024] 200 is the second external rotor permanent magnet DC brushless motor module, 201 is the second guide wheel, 202 is the second pin shaft, 203 is the second guide rail, 204 is the second large gear, 210 is the second external rotor permanent magnet DC brushless motor, 205 is the second housing, 205a is the second boss wheel shaft, 205b is the second lead hole, 211 is the second rotor, 211a is the second rotor back iron, 211b is the second magnet, 212 is the second stator, 212a is the second stator winding, 212b is the second main shaft, 212c is the second stator core, and 213 is the second pinion gear.

[0025] 300 is the first machine base assembly, 301 is the first machine base, 301a is the first ear plate, 301b is the second wire outlet hole, and 302 is the first bearing.

[0026] 400 is a two-stage planetary reducer, 401 is the first-stage planetary reducer, 401a is the first ring gear, 401b is the first sun gear, 401c is the first planetary gear, and 401d is the first planet carrier; 402 is the second-stage planetary reducer, 402a is the second ring gear, 402b is the second sun gear, 402c is the second planetary gear, and 402d is the second planet carrier, 403 is the third housing, 404 is the first flange, and 405 is the second flange.

[0027] 500 is an axial-flux permanent magnet DC brushless motor, 510 is the third stator, 501 is the third stator winding, 502 is the third stator core, 520 is the third rotor, 503 is the third main shaft, 504 is the third permanent magnet, 505 is the rotor bracket, 506 is the second base, and 506a is the second ear plate.

[0028] 600 is the third axial-flux permanent magnet DC brushless motor module. Detailed implementation mode

[0029] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] The present invention will be described in detail below with reference to the accompanying drawings.

[0031] In application scenarios with space constraints, large output torque, and the requirement for the ability to rotate freely in the X, Y, and Z axes, although existing multi-motor systems can meet indicators such as torque and degrees of freedom, the price paid is often a relatively large volume and heaviness. The purpose of the present invention is to develop a spherical joint multi-motor system with high integration, high output torque, and three rotational degrees of freedom.

[0032] Such as Figure 1 , Figure 2 , Figure 3As shown in the figure, an integrated reducer three-degree-of-freedom spherical joint motor module includes: a sphere 1, a first outer-rotor permanent magnet brushless DC motor module 100, a second outer-rotor permanent magnet brushless DC motor module 200, a first base component 300, a two-stage planetary reducer 400, and an axial-flux permanent magnet brushless DC motor 500, which together achieve rotational motion about three degrees of freedom of the X, Y, and Z axes. Among them, the first outer-rotor permanent magnet brushless DC motor module 100 integrates a first single-stage reducer, the second outer-rotor permanent magnet brushless DC motor module 200 integrates a second single-stage reducer, and the third axial-flux permanent magnet brushless DC motor module 600 integrates the axial-flux permanent magnet brushless DC motor 500 and the two-stage planetary reducer 400; the first permanent magnet brushless DC motor module 100 and the second outer-rotor permanent magnet brushless DC motor module 200 wrap the sphere 1, and the sphere 1 is designed as a hollow sphere with a flange at the top.

[0033] The spherical shape of the sphere 1 itself serves as a support. A first arc-shaped groove 1a is machined on the outer surface of the sphere 1, and a second large gear 204 is installed using screws; a second arc-shaped groove 1b is machined on the outer surface of the sphere 1 and a first large gear 104 is installed using screws. A third arc-shaped groove 1c is machined on the outer surface of the sphere 1 for installing the second guide rail 203; a fourth arc-shaped groove 1d is machined for installing the first guide rail 103. Then, the first guide rail 103 and the second guide rail 203 are fixed to the sphere 1 using screws. One third arc-shaped groove 1c is arranged on each of the left and right sides of the first arc-shaped groove 1a; one fourth arc-shaped groove 1d is arranged on each of the left and right sides of the second arc-shaped groove 1b. The plane where the first arc-shaped groove 1a is located is perpendicular to the plane where the second arc-shaped groove 1b is located in space.

[0034] As Figure 4 , Figure 5 , the first single-stage reducer includes a first large gear 104 and a first small gear 113. Four first small gears 113 are arranged along the circumference of the sphere 1, and the rotation of each first small gear 113 is independently driven by a first outer-rotor permanent magnet brushless DC motor 110. The four first small gears 113 generate torque simultaneously and constitute a first-stage reduction through meshing with the first large gear 104, achieving an effect similar to torque increase of a two-stage planetary reducer. The first large gear 104 is fixed to the sphere 1 using screws and drives the sphere 1 to rotate about the Y axis.

[0035] Similarly, the second single-stage reducer includes a second large gear 204 and a second small gear 213. Four second small gears 213 are arranged along the circumference of the sphere 1, and the rotation of each second small gear 213 is independently driven by a second outer-rotor permanent magnet brushless DC motor 210. The four second small gears 213 generate torque simultaneously and constitute a first-stage reduction through meshing with the second large gear 204, achieving an effect similar to torque increase of a two-stage planetary reducer. The second large gear 204 is fixed to the sphere 1 using screws, thereby driving the sphere 1 to rotate about the X axis. The first large gear 104 and the second large gear 204 are spatially arranged at 90 degrees.

[0036] As Figure 6 , Figure 7 shown, the first base component 300 includes a first base 301. The first base 301 has four first ear plates 301a along the circumference. Each first ear plate 301a is designed with a bearing mounting hole and a second wire outlet hole 301b for mounting a first bearing 302 and the motor lead wire. The first outer-rotor permanent magnet brushless DC motor 110 has a first housing 105, and the second outer-rotor permanent magnet brushless DC motor 210 includes a second housing 205. The first boss wheel shaft 105a of the first housing 105 and the second boss wheel shaft 205a of the second housing 205 are sleeved with the first bearing 302, and then installed into the second wire outlet hole 301b of the first base 301, so as to place the first outer-rotor permanent magnet brushless DC motor module 100, the second outer-rotor permanent magnet brushless DC motor module 200, and the sphere 1 together inside the cavity of the first base component 300.

[0037] After the axial-flux permanent magnet brushless DC motor 500 drives the first-stage planetary reducer 401 and the second-stage planetary reducer 402, through the connection of the first flange 404 with the first base 301, it drives the first base component 300, the second outer-rotor permanent magnet brushless DC motor module 200, the first outer-rotor permanent magnet brushless DC motor module 100, and the sphere 1 to rotate around the Z axis together.

[0038] A bearing is installed inside the first guide wheel 101. The first guide wheel 101 is sleeved on the first pin shaft 102. The first pin shaft 102 with threads is installed on the side end face of the first housing 105. The first guide wheel 101 and the first guide rail 103 are in trapezoidal cross-section fit, restricting the first guide rail 103 to move along the circular arc track of the three first guide wheels 101, that is, to rotate around the Y axis.

[0039] Similarly, a bearing is installed inside the second guide wheel 201. The second guide wheel 201 is sleeved on the second pin shaft 202. The second pin shaft 202 with threads is installed on the side end face of the second housing 205. The second guide wheel 201 and the second guide rail 203 are in trapezoidal cross-section fit, restricting the second guide rail 203 to move along a circular arc with respect to the three second guide wheels 201, that is, to rotate around the X axis.

[0040] The weights of the sphere 1, the first outer-rotor permanent magnet brushless DC motor module 100, and the second outer-rotor permanent magnet brushless DC motor module 200 are supported by the four first bearings 302.

[0041] According to the design requirements, considering the wire winding problem generated during the full-circle rotation of the first outer-rotor permanent magnet brushless DC motor module 100 and the second outer-rotor permanent magnet brushless DC motor module 200, a hollow shaft solution is adopted for the first boss wheel shaft 105a and the second boss wheel shaft 205a. The lead wires are led out from the hollow shaft to connect the controller assembly and the battery, and the controller assembly and the battery are fixed to the first base 301 using screws.

[0042] The host computer sets the motion angle range of the first outer-rotor permanent magnet brushless DC motor module 100 and the second outer-rotor permanent magnet brushless DC motor module 200 to only perform a similar pendulum motion (±40°). The third axial-flux permanent magnet brushless DC motor module 600 realizes a full-circle rotation around the Z-axis without wire winding problems.

[0043] The cooperation between the 12 first guide wheels 101 of the first outer-rotor permanent magnet brushless DC motor module 100 and the first guide rail 103, and the cooperation between the 12 second guide wheels 201 of the second outer-rotor permanent magnet brushless DC motor module 200 and the second guide rail 203 jointly support the weight of the sphere 1 and limit the displacement along the three directions of XYZ.

[0044] An absolute position encoder is installed according to the design requirements and sleeved on the first boss wheel shaft 105a and the second boss wheel shaft 205a for position detection of the first outer-rotor permanent magnet brushless DC motor module 100 and the second outer-rotor permanent magnet brushless DC motor module 200. Similarly, an absolute position encoder is installed on the third axial-flux permanent magnet brushless DC motor module 600 for position detection.

[0045] As Figure 8 , the first outer-rotor permanent magnet brushless DC motor module 100 includes a first outer-rotor permanent magnet brushless DC motor 110 and a first large gear 104. The first rotor 111 of the first outer-rotor permanent magnet brushless DC motor 110 has a first rotor back iron 111a and first magnetic steels 112b. The first stator 112 has a first stator winding 112a, a first main shaft 112b, and a first stator core 112c. The first outer-rotor permanent magnet brushless DC motor 110 is located inside the first pinion 113, and the first rotor back iron 111a is connected to the first pinion 113 using a key or screws. The first pinion 113 and the first large gear 104 form a main reducer.

[0046] Similarly, the second outer rotor permanent magnet brushless DC motor module 200 includes a second outer rotor permanent magnet brushless DC motor 210 and a second large gear 204. The second rotor 211 of the second outer rotor permanent magnet brushless DC motor 210 has a second rotor back iron 211a and second magnetic steel 211b. The stator part has a second stator winding 212a, a second main shaft 212b, and a second stator core 212c. The second outer rotor permanent magnet brushless DC motor 210 is located within the second small gear 203, and the second rotor back iron 211a is connected to the second small gear 213 using a key or screws. The second small gear 213 and the second large gear 204 form a main speed reducer.

[0047] The three-phase lead wires of the first stator winding 112a are led out from the first lead hole 105b; the three-phase lead wires of the second stator winding 212a are led out from the second lead hole 205b.

[0048] Such as Figure 9 , Figure 10 , the third axial flux permanent magnet brushless DC motor module 600 includes a two-stage planetary speed reducer 400 and an axial flux permanent magnet brushless DC motor 500, where the two-stage planetary speed reducer 400 is composed of a series connection of two-stage planetary speed reducers, namely a first-stage planetary speed reducer 401 and a second-stage planetary speed reducer 402.

[0049] The first-stage planetary speed reducer 401 includes a first ring gear 401a, a first sun gear 401b, first planet gears 401c, and a first planet carrier 401d. The first ring gear 401a, the first sun gear 401b, and the four first planet gears 401c are in mutual tooth engagement, and the four first planet gears 401c are sleeved on the first planet carrier 401d to rotate together.

[0050] Similarly, the second-stage planetary speed reducer 402 includes a second ring gear 402a, a second sun gear 402b, second planet gears 402c, and a second planet carrier 402d. The second ring gear 402a, the second sun gear 402b, and the three second planet gears 402c are in mutual tooth engagement, and the three second planet gears 402c are sleeved on the second planet carrier 402d to rotate together.

[0051] The two-stage planetary speed reducer 400 also includes a third housing 403. The first-stage planetary speed reducer 401 and the second-stage planetary speed reducer 402 are installed in series inside the third housing 403 to form a two-stage planetary speed reducer. The second planet carrier 402d of the second-stage planetary speed reducer 402 is connected to the first flange 404 by screws, and the first flange 404 is connected to the first machine base 301 by screws.

[0052] The third main shaft 503 of the axial flux permanent magnet brushless DC motor 500 is connected to the first sun gear 401b of the first-stage planetary speed reducer 401.

[0053] The axial flux permanent magnet brushless DC motor 500 includes two third stators 510 and a third rotor 520. The third stator 510 includes a third stator winding 501, a third stator core 502, and a second base 506. The second base 506 is designed with a second ear plate 506a for providing stable support for the axial flux permanent magnet brushless DC motor 500. The third rotor 520 includes a third main shaft 503, third magnets 504, and a rotor bracket 505.

[0054] The third main shaft 503 is inserted into the cavity of the first sun gear 401b of the first-stage planetary reducer 401, and the protruding shaft of the first planet carrier 401d is inserted into the second sun gear 402b. Thus, the third rotor 520 of the axial flux permanent magnet brushless DC motor 500 drives the two-stage planetary reducer 400 to rotate, and the rotation of the second planet carrier 402d drives the first machine base 301 to rotate around the Z axis.

[0055] Based on Figure 1 for expansion, such as Figure 11 , Figure 12 , the spatial position of the third axial flux permanent magnet brushless DC motor module 600 relative to the sphere 1 is given. Figure 11 is the internal structure diagram of the third axial flux permanent magnet brushless DC motor module 600 completely sunk inside the sphere 1. Figure 9 is the internal structure diagram of the partial sinking inside the sphere 1. In Figure 11 , Figure 12 's solution, the first machine base 301 remains stationary, and the first outer rotor permanent magnet brushless DC motor module 100, the second outer rotor permanent magnet brushless DC motor module 200, and the third axial flux permanent magnet brushless DC motor module 600 are each responsible for the rotation of the coordinate axes XYZ. This layout can be applied to scenarios such as vector vehicle lights and vector propellers.

[0056] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An integrated reducer three-degree-of-freedom spherical joint motor module, characterized in that Comprising: A sphere, a first outer-rotor permanent magnet brushless DC motor module, a second outer-rotor permanent magnet brushless DC motor module, a third axial-flux permanent magnet brushless DC motor module, and a first housing assembly; wherein, the first outer-rotor permanent magnet brushless DC motor module integrates a first single-stage reducer, the second outer-rotor permanent magnet brushless DC motor module integrates a second single-stage reducer, and the third axial-flux permanent magnet brushless DC motor module integrates a two-stage planetary reducer; Wherein, the first outer-rotor permanent magnet brushless DC motor module and the second outer-rotor permanent magnet brushless DC motor module are located on the outer surface of the sphere and are arranged at a 90-degree angle in space. The first outer-rotor permanent magnet brushless DC motor module, the second outer-rotor permanent magnet brushless DC motor module, and the sphere are placed in the first housing assembly. The first outer-rotor permanent magnet brushless DC motor module is used to rotate the sphere around the Y-axis; the second outer-rotor permanent magnet brushless DC motor module is used to rotate the sphere around the X-axis; the third axial-flux permanent magnet brushless DC motor module drives the first outer-rotor permanent magnet brushless DC motor module, the second outer-rotor permanent magnet brushless DC motor module, the sphere, and the first housing assembly as a whole to rotate around the Z-axis.

2. The three-degree-of-freedom spherical joint motor module integrated with a speed reducer according to claim 1, wherein The first single-stage reducer includes a first large gear and a first small gear. A plurality of first small gears are arranged along the circumference of the sphere. The rotation of each first small gear is driven by the first outer-rotor permanent magnet brushless DC motor. The first small gears generate torque simultaneously and constitute the first-stage reduction by meshing with the first large gear. The first large gear is fixed to the sphere to drive the sphere to rotate around the Y-axis.

3. The three-degree-of-freedom spherical joint motor module integrated with a speed reducer according to claim 1, characterized in that, The second single-stage reducer includes a second large gear and a second small gear. A plurality of second small gears are arranged along the circumference of the sphere. The rotation of each second small gear is driven by the second outer-rotor permanent magnet brushless DC motor. The plurality of second small gears generate torque simultaneously and constitute the first-stage reduction by meshing with the second large gear. The second large gear is fixed to the sphere by screws to drive the sphere to rotate around the X-axis.

4. The three-degree-of-freedom spherical joint motor module integrated with a speed reducer according to claim 2, characterized in that The first outer-rotor permanent magnet brushless DC motor module further includes a first outer-rotor permanent magnet brushless DC motor. The first rotor of the first outer-rotor permanent magnet brushless DC motor has a first rotor back iron and first magnetic steel. The first stator of the first outer-rotor permanent magnet brushless DC motor has a first stator winding, a first main shaft, and a first stator core. The first outer-rotor permanent magnet brushless DC motor is located inside the first small gear. Wherein, the first rotor back iron is connected to the first small gear.

5. The three-degree-of-freedom spherical joint motor module integrated with a speed reducer according to claim 3, characterized in that The second outer-rotor permanent magnet brushless DC motor module further includes a second outer-rotor permanent magnet brushless DC motor. The second rotor of the second outer-rotor permanent magnet brushless DC motor has a second rotor back iron and second magnetic steel. The stator part has a second stator winding, a second main shaft, and a second stator core. The second outer-rotor permanent magnet brushless DC motor is located inside the second small gear. Wherein, the second rotor back iron is connected to the second small gear.

6. The three-degree-of-freedom spherical joint motor module integrated with a speed reducer according to claim 1, wherein, The third axial flux permanent magnet brushless DC motor module includes a two-stage planetary reducer and an axial flux permanent magnet brushless DC motor. The two-stage planetary reducer is composed of two-stage planetary reducers in series, namely the first-stage planetary reducer and the second-stage planetary reducer. The first-stage planetary reducer includes a first ring gear, a first sun gear, first planet gears and a first planet carrier. The first ring gear, the first sun gear and the four first planet gears are meshed with each other, and the four first planet gears are sleeved on the first planet carrier. The second-stage planetary reducer includes a second ring gear, a second sun gear, second planet gears and a second planet carrier. The second ring gear, the second sun gear and the three second planet gears are meshed with each other, and the three second planet gears are sleeved on the second planet carrier. The two-stage planetary reducer also includes a third housing. The first-stage planetary reducer and the second-stage planetary reducer are installed in series inside the third housing. The second planet carrier is connected to a first flange, and the first flange is connected to a first base assembly. The third output shaft of the axial flux permanent magnet brushless DC motor is connected to the first sun gear of the first-stage planetary reducer. The axial flux permanent magnet brushless DC motor includes two third stators and a third rotor. The third stator includes a third stator winding, a third stator core and a second base. The third rotor includes a third main shaft, third permanent magnets and a rotor bracket. The third main shaft is inserted into the cavity of the first sun gear of the first-stage planetary reducer, and the extended shaft of the first planet carrier is inserted into the second sun gear.

7. The three-degree-of-freedom spherical joint motor module integrated with a speed reducer according to claim 1, characterized in that, The first base assembly includes a first base. The first base has four first ear plates along the circumference. Each first ear plate is provided with a bearing mounting hole and a second wire outlet hole for mounting a first bearing and leading out wires. The first outer rotor permanent magnet brushless DC motor has a first housing, and the second outer rotor permanent magnet brushless DC motor includes a second housing. The first boss wheel shaft of the first housing and the second boss wheel shaft of the second housing are sleeved with a first bearing and then installed into the second wire outlet hole of the first base. The first outer rotor permanent magnet brushless DC motor module, the second outer rotor permanent magnet brushless DC motor module and the sphere are placed together inside the cavity of the first base assembly.

8. The three-degree-of-freedom spherical joint motor module integrated with a speed reducer according to claim 1, characterized in that A first arc groove is machined on the outer surface of the sphere for mounting a second large gear; a second arc groove is machined on the outer surface of the sphere for a first large gear; a third arc groove is machined on the outer surface of the sphere for mounting a second guide rail; a fourth arc groove is machined on the outer surface of the sphere for mounting a first guide rail. One third arc groove is arranged on each of the left and right sides of the first arc groove; one fourth arc groove is arranged on each of the left and right sides of the second arc groove. The plane where the first arc groove is located is perpendicular to the plane where the second arc groove is located in space.

9. The three-degree-of-freedom spherical joint motor module integrated with a speed reducer according to claim 8, characterized in that A bearing is installed inside the first guide wheel. The first guide wheel is sleeved on a first pin shaft. The first pin shaft with threads is installed on the side end face of the first housing of the first outer rotor permanent magnet brushless DC motor. The first guide wheel and the first guide rail are matched through a trapezoidal cross section to limit the movement of the first guide rail along the circular arc track of the first guide wheel, that is, to rotate around the Y axis.

10. The three-degree-of-freedom spherical joint motor module integrated with a speed reducer according to claim 9, characterized in that, A bearing is installed inside the second guide wheel. The second guide wheel is sleeved onto the second pin shaft, and the threaded second pin shaft is installed on the side end face of the second housing of the second outer rotor permanent magnet DC brushless motor. The second guide wheel and the second guide rail are matched through a trapezoidal cross section to limit the second guide rail to move in an arc along the second guide wheel, that is, to rotate around the X axis.

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