A three-degree-of-freedom spherical joint motor module for humanoid robots

Abstract

The present invention proposes a three-degree-of-freedom spherical joint motor module for use in a humanoid robot, belonging to the field of humanoid robots. The module comprises: a sphere, a first permanent magnet brushless DC motor, a second permanent magnet brushless DC motor, and a third permanent magnet brushless DC motor. The first permanent magnet brushless DC motor and the second permanent magnet brushless DC motor are located on the outer surface of the sphere and arranged at 90 degrees in space. The first permanent magnet brushless DC motor is used to rotate the sphere around the X-axis; the second permanent magnet brushless DC motor is used to rotate the sphere around the Y-axis; and the third permanent magnet brushless DC motor drives the first permanent magnet brushless DC motor, the second permanent magnet brushless DC motor, and the sphere as a whole to rotate around the Z-axis. The spherical joint motor module of the present invention enables each motor to rotate 360 ​​degrees around its respective rotation axis, significantly expanding the range of motion of the sphere. The module has the advantages of a compact structure and high space utilization.

Description

Technical Field

[0001] The present invention is applied to the field of humanoid robots, and particularly relates to a three-degree-of-freedom spherical joint motor module applied to a humanoid robot. Background Art

[0002] The shoulder and hip joints of humanoid robots utilize three independent joint motors to form a three-degree-of-freedom joint motor system. While this system can achieve high torque transmission, it suffers from drawbacks such as low integration and large footprint. As a branch of three-degree-of-freedom systems, spherical joint motor systems with integrated three-degree-of-freedom (DOF) rotations integrate three motors within a sphere or shell to achieve three-rotational coordinate motion and have become a research hotspot in recent years.

[0003] The application with publication number CN115042224A, entitled "A Multi-Degree-of-Freedom Spherical Electric Joint," discloses a multi-degree-of-freedom spherical electric joint. The working principle is that a connecting shaft is designed on the inner side of the third rotor located in the spherical frame, and the output shaft passes through the cross-connection of the first rotor and the second rotor. The output shaft is connected to the connecting shaft through a universal joint, thereby realizing the decoupling of the three-degree-of-freedom motion of the joint, simplifying the control, and improving the output torque. The characteristic is that the third rotor only drives the rotation of its own shaft, and is independent of the first rotor and the second rotor. The disadvantage of this application is that the weight of the first motor, the second motor, and the third motor in the sphere lacks effective bearing support, and the stator and rotor of each motor lack effective axial positioning and alignment.

[0004] Application Publication No. CN115229839A, entitled "A Three-Degree-of-Freedom Spherical Joint Structure," discloses a three-degree-of-freedom spherical joint structure composed of three joint motors placed within a spherical shell, independently controlling rotation about each axis. Features include a simple structure, compact size, high output torque, easy installation and maintenance, and a wide range of three-degree-of-freedom motion. However, this application suffers from a significant lack of effective utilization of the internal space within the sphere, resulting in a relatively large sphere footprint. 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 for a humanoid robot. In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A three-degree-of-freedom spherical joint motor module for a humanoid robot includes: a sphere, a first permanent magnet brushless DC motor, a second permanent magnet brushless DC motor, and a third permanent magnet brushless DC motor;

[0007] Among them, the first permanent magnet brushless DC motor and the second permanent magnet brushless DC motor are located on the outer surface of the sphere and arranged at 90 degrees in space. The first permanent magnet brushless DC motor is used to realize the rotation of the sphere around the X axis; the second permanent magnet brushless DC motor is used to realize the rotation of the sphere around the Y axis; the third permanent magnet brushless DC motor drives the first permanent magnet brushless DC motor, the second permanent magnet brushless DC motor and the sphere as a whole to rotate around the Z axis.

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

[0009] The ball joint motor of the present invention enables each motor to rotate 360 ​​degrees around its own rotation axis, significantly expanding the range of motion of the sphere, and has the advantages of compact structure and high space utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is an axonometric diagram of a three-degree-of-freedom spherical joint motor module of the present invention;

[0011] Figure 2 This is a cross-sectional view of a three-degree-of-freedom spherical joint motor module of the present invention;

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

[0013] Figure 4 This is a structural diagram of two sets of permanent magnet brushless DC motors wrapped around a sphere according to the present invention;

[0014] Figure 5 This is an exploded view of a three-degree-of-freedom spherical joint motor module of the present invention;

[0015] Figure 6 Exploded diagram of the first permanent magnet brushless DC motor and the second permanent magnet brushless DC motor of the present invention;

[0016] Figure 7 This is an exploded view of the third permanent magnet brushless DC motor of the present invention.

[0017] 1 is a sphere, 1a is a first arcuate groove, 1b is a second arcuate groove, 1c is a third arcuate groove, and 1d is a fourth arcuate groove.

[0018] 100 is the first permanent magnet DC brushless motor, 101 is the first stator core, 102 is the first stator winding, 103 is the first rotor magnet, 104 is the first rotor back iron, 105 is the first guide rail, 106 is the first pin shaft, 107 is the first guide wheel, 108 is the first housing, 108a is the first boss wheel shaft, 109 is the first controller, 110 is the first stator, 111 is the first battery, 120 is the first rotor, and 130 is the first controller assembly.

[0019] 200 is a second permanent magnet brushless DC motor, 201 is a second stator core, 202 is a second stator winding, 203 is a second rotor magnet, 204 is a second rotor back iron, 205 is a second guide rail, 206 is a second pin shaft, 207 is a second guide wheel, 208 is a second housing, 208a is a second boss wheel shaft, 209 is a second controller, 210 is a second stator, 211 is a second battery, 220 is a second rotor, and 230 is a second controller assembly.

[0020] 300 is a third permanent magnet DC brushless motor, 301 is a third stator winding, 302 is a third stator core, 303 is a third rotor magnet, 304 is a third rotor back iron, 305 is a key, 306a is a first bearing, 306b is a second bearing, 307 is a rotor bracket, 307a is a first boss, 307b is a second boss, 307c is a first lead hole, 307d is a second lead hole, 308 is a first retaining ring, 309 is a cross roller bearing, 310 is a third stator, 311 is a third housing, 312 is a second retaining ring, 313 is a third control assembly, and 320 is a third rotor. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are merely illustrative of the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0022] The present invention will be described in detail below with reference to the accompanying drawings.

[0023] like Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 As shown, a three-degree-of-freedom spherical joint motor module consists of three parts: a sphere 1, a first permanent magnet DC brushless motor 100, a second permanent magnet DC brushless motor 200, and a third permanent magnet DC brushless motor 300, which respectively realize three degrees of freedom rotation around the XYZ axes.

[0024] A first permanent magnet brushless DC motor 100 and a second permanent magnet brushless DC motor 200 surround sphere 1, which is designed as a hollow sphere with a flange on top. The first and second permanent magnet brushless DC motors 100 and 200 are arranged at 90 degrees. The first permanent magnet brushless DC motor 100 rotates sphere 1 about the X-axis, while the second permanent magnet brushless DC motor 200 rotates sphere 1 about the Y-axis. A third permanent magnet brushless DC motor 300 drives the first and second permanent magnet brushless DC motors 100 and 200 to rotate as a whole about the Z-axis.

[0025] like Figure 6 , Figure 7 As shown, the first permanent magnet brushless DC motor 100 includes a first stator 110 , a first rotor 120 and a first housing 108 . The first stator 110 includes a first stator core 101 and a first stator winding 102 . The first rotor 120 includes a first rotor magnet 103 and a first rotor back iron 104 .

[0026] The second permanent magnet brushless DC motor 200 includes a second stator 210 , a second rotor 220 and a second housing 208 . The second stator 210 includes a second stator core 201 and a second stator winding 202 . The second rotor 220 includes a second rotor magnet 203 and a second rotor back iron 204 .

[0027] The third permanent magnet brushless DC motor 300 includes a third stator 310 , a third rotor 320 and a third housing 311 . The third stator 310 includes a third stator core 302 and a third stator winding 301 . The third rotor 320 includes a third rotor magnet 303 and a third rotor back iron 304 .

[0028] Using the spherical shape of the sphere 1 as support, a first arcuate groove 1a is machined on the outer surface of the sphere 1 for mounting the first rotor magnet 103 and the first rotor back iron 104; a second arcuate groove 1b is machined for mounting the second rotor magnet 203 and the second rotor back iron 204. The first and second rotor back irons 104 and 204 are fixed to the first and second arcuate grooves 1a and 1b of the sphere 1 using screws. The first and second rotor magnets 103 and 203 are respectively adhered to the first and second rotor back irons 104 and 204 using epoxy glue. The inner and outer walls of the first and second rotor magnets 103 and 203 are designed to be spherical, with equal side lengths. This allows the magnet at the bottom of the sphere 1 to be shared by both the first and second rotor magnets 103 and 203.

[0029] A third arcuate groove 1c is machined on the outer surface of sphere 1 for mounting first guide rail 105; a fourth arcuate groove 1d is machined for mounting second guide rail 205. Screws are then used to secure first and second guide rails 105, 205, to sphere 1. A third arcuate groove 1c is positioned on either side of first arcuate groove 1a; a fourth arcuate groove 1d is positioned on either side of second arcuate groove 1b. The plane of first arcuate groove 1a is perpendicular to the plane of second arcuate groove 1b.

[0030] The first guide wheel 107 has a bearing installed inside. The first guide wheel 107 is mounted on the first pin 106, which is then threaded and mounted on the side surface of the first housing 108. The first guide wheel 107 cooperates with the first guide rail 105 to restrict the first guide rail 105 from moving along the circular path of the three first guide wheels 107, i.e., rotating about the X-axis. Similarly, the second guide wheel 207 has a bearing installed inside. The second guide wheel 207 is mounted on the second pin 206, which is then threaded and mounted on the side surface of the second housing 208. The second guide wheel 207 cooperates with the second guide rail 205 to restrict the second guide rail 205 from moving along the circular path of the three second guide wheels 207, i.e., rotating about the Y-axis.

[0031] The first housing 108 of the first permanent magnet brushless DC motor 100 is designed with circular first boss axles 108a at both ends, and these first boss axles 108a are fitted with first bearings 306a. The second housing 208 of the second permanent magnet brushless DC motor 200 is designed with circular second boss axles 208a at both ends, and these second boss axles 208a are fitted with second bearings 306b. The first and second bearings 306a, 306b are mounted in the inner wall holes of the rotor bracket 307. The weight of the sphere 1, the first permanent magnet brushless DC motor 100, and the second permanent magnet brushless DC motor 200 is supported by four bearings, namely the first and second bearings 306a, 306b.

[0032] The third permanent magnet brushless DC motor 300 also includes a first retaining ring 308, a second retaining ring 312, a cross-roller bearing 309, and a rotor bracket 307. The third stator 310 includes a third stator winding 301 and a third stator core 302. The third stator 310 is placed within a third housing 311, with its circular motion limited by a key 305 on the third stator core 302. The second retaining ring 312 is fixed to the third housing 311 with screws to compress the third stator 310. The third rotor 320 includes a third rotor magnet 303 and a third rotor back iron 304. The outer ring of the cross-roller bearing 309 is fixed to the third housing 311 with screws. Screws are used to secure the inner ring of the cross-roller bearing 309, the first retaining ring 308, the rotor bracket 307, and the third rotor 320.

[0033] The rotor bracket 307 is designed with a first boss 307a and a second boss 307b on the upper and lower end surfaces. The first boss 307a is designed with a first lead hole 307c for use as a lead wire outlet hole for the second stator winding 202; the second boss 307b is designed with a second lead hole 307d for use as a lead wire outlet hole for the first stator winding 102.

[0034] Based on design requirements and considering the wire entanglement issues that may arise during the full rotation of the first and second permanent magnet brushless DC motors 100 and 200, wireless charging and wireless communication can be used to address both power and communication issues. Alternatively, the first and second boss axles 108a and 208a can be hollow shafts, with lead wires extending from the hollow shafts to connect to the controller assembly and battery. Alternatively, the host computer can configure the angular range of motion for each motor to enable a simple pendulum-like motion (±90°). The third permanent magnet brushless DC motor 300 is spatially positioned at the outermost periphery, eliminating the wire entanglement issue. The third rotor can achieve full rotation, and power can be directly supplied to the third permanent magnet brushless DC motor 300 via the battery-controller.

[0035] The twelve first guide wheels 107 of the first permanent magnet brushless DC motor 100 cooperate with the first guide rail 105, and the twelve second guide wheels 207 of the second permanent magnet brushless DC motor 200 cooperate with the second guide rail 205 to jointly support the weight of the sphere 1 and limit the movement displacement along the three directions of XYZ.

[0036] The cross roller bearing 309 supports the weight of the first permanent magnet brushless DC motor 100 , the second permanent magnet brushless DC motor 200 and the third rotor 320 , and rotates as a whole relative to the third stator 310 .

[0037] The first stator 110 is fixed to the first housing 108 via screws. The relative rotation between the first stator 110 and the first rotor 120 is achieved through the relative motion between the first guide rail 105 and the first guide wheels 107. The relative motion between the first guide rail 105 and the three first guide wheels 107 is specifically achieved by the first guide rail 105 being fixed to the sphere 1. The rotation of the first rotor 120 drives the sphere 1 and the second permanent magnet brushless DC motor 200 to rotate as a whole about the X-axis.

[0038] Similarly, the second stator 210 is fixed to the second housing 208 via screws. The relative rotation between the second stator 210 and the second rotor 220 is achieved through the relative motion between the second guide rail 205 and the second guide wheels 207. The relative motion between the second guide rail 205 and the three second guide wheels 207 is specifically achieved by the second guide rail 205 being fixed to the sphere 1, and the second rotor 220 rotating to drive the sphere 1 and the first permanent magnet brushless DC motor 100 to rotate together about the Y-axis.

[0039] The third permanent magnet brushless DC motor 300 drives the third rotor 320 to rotate, thereby driving the first permanent magnet brushless DC motor 100 and the second permanent magnet brushless DC motor 200 to rotate around the Z axis as a whole.

[0040] Furthermore, the system includes a first controller assembly 130, a second controller assembly 230, and a third control assembly 313. The first controller assembly 130 is used to control the first permanent magnet brushless DC motor 100 and includes a first controller 109 and a first battery 111. The second controller assembly 230 is used to control the second permanent magnet brushless DC motor 200 and includes a second controller 209 and a second battery 211. The first and second controller assemblies 130 and 230 are fixed to the end face of the rotor bracket 307 via screws and rotate with the third rotor 320. The third control assembly 313 is used to control the third permanent magnet brushless DC motor 300 and is fixed to the bottom of the third housing 311 via screws and is powered directly by an external DC power supply.

[0041] The inner and outer walls of the first, second, and third rotor magnets 103, 203, and 303 are designed to be spherical. The first, second, and third stator cores 101, 201, and 302 are made of SMC, facilitating their spherical design. The inner and outer walls of the first and second stator cores 101, 201, and 302 are designed to be spherical, while the inner wall of the third stator core 302 is also designed to be spherical.

[0042] Absolute position encoders are installed according to design requirements and mounted on first boss axle 108a and second boss axle 208a to detect the positions of first permanent magnet brushless DC motor 100 and second permanent magnet brushless DC motor 200. Similarly, an absolute position encoder is installed on the rotor of third permanent magnet brushless DC motor 300 for position detection.

[0043] The third permanent magnet brushless DC motor 300 drives the third rotor 320 to rotate, thereby driving the rotor bracket 307 to drive the first permanent magnet brushless DC motor 100 and the second permanent magnet brushless DC motor 200 to rotate as a whole around the Z axis. The third rotor 320 is supported by the cross roller bearing 309.

[0044] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A three-degree-of-freedom spherical joint motor module for a humanoid robot, characterized in that: include: sphere, a first permanent magnet brushless DC motor, a second permanent magnet brushless DC motor, and a third permanent magnet brushless DC motor; Among them, the first permanent magnet brushless DC motor and the second permanent magnet brushless DC motor are located on the outer surface of the sphere and arranged at 90 degrees in space. The first permanent magnet brushless DC motor is used to realize the rotation of the sphere around the X axis; the second permanent magnet brushless DC motor is used to realize the rotation of the sphere around the Y axis; the third permanent magnet brushless DC motor drives the first permanent magnet brushless DC motor, the second permanent magnet brushless DC motor and the sphere as a whole to rotate around the Z axis; The first permanent magnet brushless DC motor includes a first stator, a first rotor, and a first housing, the first stator including a first stator core and a first stator winding, and the first rotor including a first rotor magnet and a first rotor back iron; the second permanent magnet brushless DC motor includes a second stator, a second rotor, and a second housing, the second stator including a second stator core and a second stator winding, and the second rotor including a second rotor magnet and a second rotor back iron; the third permanent magnet brushless DC motor includes a third stator, a third rotor, and a third housing, the third stator including a third stator core and a third stator winding, and the third rotor including a third rotor magnet and a third rotor back iron; The outer surface of the sphere has a first arc groove for installing the first rotor magnet and the first rotor back iron; the outer surface of the sphere has a second arc groove for installing the second rotor magnet and the second rotor back iron, the first rotor back iron and the second rotor back iron are fixed to the first and second arc grooves of the sphere, the first rotor magnet and the second rotor magnet are fixed to the first rotor back iron and the second rotor back iron, the inner and outer wall surfaces of the first rotor magnet and the second rotor magnet are designed to be spherical and the side lengths of the spherical surfaces of the magnets are equal; a third arc groove is provided on the outer surface of the sphere for installing the first guide rail; a fourth arc groove is provided on the outer surface of the sphere for installing the second guide rail, and then the first guide rail and the second guide rail are fixed to the sphere, a third arc groove is arranged on each side of the left and right sides of the first arc groove; a fourth arc groove is arranged on each side of the left and right sides of the second arc groove, and the plane where the first arc groove is located is perpendicular to the plane where the second arc groove is located in space.

2. The three-degree-of-freedom spherical joint motor module for a humanoid robot according to claim 1, characterized in that: A bearing is installed inside the first guide wheel, and the first guide wheel is mounted on the first pin shaft, and the first pin shaft is mounted on the side end surface of the first housing. The first guide wheel cooperates with the first guide rail to limit the first guide rail to move along the circular trajectory of the first guide wheel, that is, to rotate around the X-axis; a bearing is installed inside the second guide wheel, and the second guide wheel is mounted on the second pin shaft, and the second pin shaft is mounted on the side end surface of the second housing. The second guide wheel cooperates with the second guide rail to limit the second guide rail to move in a circular arc along the second guide wheel, that is, to rotate around the Y-axis.

3. The three-degree-of-freedom spherical joint motor module for a humanoid robot according to claim 2, characterized in that: A first boss axle is provided at both ends of the first housing of the first permanent magnet brushless DC motor, and the first boss axle is sleeved on the first bearing; a second boss axle is provided at both ends of the second housing of the second permanent magnet brushless DC motor, and the second boss axle is sleeved on the second bearing, the first bearing and the second bearing are installed in the inner wall hole of the rotor bracket of the third permanent magnet brushless DC motor, and the weight of the sphere, the first permanent magnet brushless DC motor and the second permanent magnet brushless DC motor is supported by the first bearing and the second bearing.

4. The three-degree-of-freedom spherical joint motor module for a humanoid robot according to claim 1, characterized in that: The third permanent magnet brushless DC motor also includes a first retaining ring, a second retaining ring, a cross-roller bearing, and a rotor bracket; the third stator is placed inside the cavity of the third housing and its circular motion is limited by a key; the second retaining ring is fixed to the third housing for pressing the third stator; the outer ring of the cross-roller bearing is fixed to the third housing, and the inner ring of the cross-roller bearing, the first retaining ring, the rotor bracket, and the third rotor are fixed together.

5. The three-degree-of-freedom spherical joint motor module for a humanoid robot according to claim 4, characterized in that: The rotor bracket is designed with a first boss and a second boss on the upper and lower end surfaces. The first boss is designed with a first lead-out hole for the lead-out wire of the second stator winding; the second boss is designed with a second lead-out hole for the lead-out wire of the first stator winding.

6. The three-degree-of-freedom spherical joint motor module for a humanoid robot according to claim 4, characterized in that: The cross roller bearing supports the weight of the first permanent magnet brushless DC motor, the second permanent magnet brushless DC motor and the third rotor, and the whole rotates relative to the third stator.

7. The three-degree-of-freedom spherical joint motor module for a humanoid robot according to claim 6, characterized in that: The first stator is fixed to the first housing. The relative rotation between the first stator and the first rotor is achieved by the relative movement of the first guide rail and the first guide wheel. The first guide rail is fixed to the sphere. The rotation of the first rotor drives the sphere and the second permanent magnet DC brushless motor to rotate as a whole around the X-axis. The second stator is fixed to the second housing. The relative rotation between the second stator and the second rotor is achieved by the relative movement of the second guide rail and the second guide wheel. The second guide rail is fixed to the sphere. The second rotor rotates to drive the sphere and the first permanent magnet brushless DC motor to rotate as a whole around the Y axis. The third permanent magnet brushless DC motor drives the third rotor to rotate, thereby driving the first permanent magnet brushless DC motor and the second permanent magnet brushless DC motor to rotate around the Z axis as a whole.

8. The three-degree-of-freedom spherical joint motor module for a humanoid robot according to claim 2, characterized in that: It also includes a first controller component, a second controller component, and a third control component; the first controller component is used to control the first permanent magnet DC brushless motor, and includes a first controller and a first battery; the second controller component is used to control the second permanent magnet DC brushless motor, and includes a second controller and a second battery. The first controller component and the second controller component are fixed to the end face of the rotor bracket and rotate with the third rotor. The third control component is used to control the third permanent magnet DC brushless motor, and the third control component is fixed to the bottom of the third housing and is directly powered by an external DC power supply.

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