Three-degree-of-freedom spherical joint motor module applied to humanoid robot

Abstract

The invention provides a three-degree-of-freedom spherical joint motor module applied to a humanoid robot, and belongs to the field of humanoid robots. The three-degree-of-freedom spherical joint motor module comprises a sphere, a first permanent magnet direct current brushless motor, a second permanent magnet direct current brushless motor and a third permanent magnet direct current brushless motor; wherein the first permanent magnet direct current brushless motor and the second permanent magnet direct current brushless motor are located on the outer surface of the ball body and are arranged at an angle of 90 degrees in space, and the first permanent magnet direct current brushless motor is used for achieving rotation of the ball body around the X axis; the second permanent magnet direct current brushless motor is used for realizing rotation of the sphere around the Y axis; the third permanent magnet brushless direct current motor drives the first permanent magnet brushless direct current motor, the second permanent magnet brushless direct current motor and the sphere to rotate around the Z axis as a whole. The spherical joint motor module realizes 360-degree rotation of each motor around the respective rotating shaft, remarkably expands the movement range of the sphere, and has the advantages of compact structure, high space utilization rate and the like.

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 for humanoid robots. Background Art

[0002] For the shoulder joints and hip joints of humanoid robots, a three-rotation-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.

[0003] In the application with publication number CN115042224A and invention name "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 intersection 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 disadvantage of this application is that the self-weights of the first motor, the second motor, and the third motor inside the sphere lack effective bearing support, and the stators and rotors of each motor lack effective axial positioning and centering.

[0004] In the application with publication number CN115229839A and invention name "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 for humanoid robots. 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 for humanoid robots, comprising: a sphere, a first permanent magnet direct current brushless motor, a second permanent magnet direct current brushless motor, and a third permanent magnet direct current brushless 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 are arranged at a 90-degree angle 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 spherical joint motor of the present invention realizes 360-degree rotation of each motor around its respective rotation axis, significantly expanding the movement range of the sphere. It has the advantages of compact structure and high space utilization rate. Brief Description of the Drawings

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

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

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

[0013] Figure 4 is a structural diagram of two groups of permanent magnet brushless DC motors of the present invention wrapping the sphere;

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

[0015] Figure 6 is an exploded view of the first permanent magnet brushless DC motor and the second permanent magnet brushless DC motor of the present invention;

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

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

[0018] 100 is the first permanent magnet brushless DC 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, 130 is the first controller assembly.

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

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

[0021] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with 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.

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

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

[0024] The first permanent magnet brushless DC motor 100 and the second permanent magnet brushless DC motor 200 wrap the sphere 1, and the sphere 1 is designed as a hollow sphere with a flange at the top. The first permanent magnet brushless DC motor 100 and the second permanent magnet brushless DC motor 200 are spatially arranged at 90 degrees. The first permanent magnet brushless DC motor 100 is used to rotate the sphere 1 around the X-axis, and the second permanent magnet brushless DC motor 200 is used to rotate the sphere 1 around the Y-axis. The third permanent magnet brushless DC motor 300 drives 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.

[0025] As Figure 6 , Figure 7 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, and 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, and 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, and 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 itself as a support, a first arc-shaped groove 1a is machined on the outer surface of the sphere 1 for installing the first rotor magnet 103 and the first rotor back iron 104; a second arc-shaped groove 1b is machined for installing the second rotor magnet 203 and the second rotor back iron 204. Screws are used to fix the first rotor back iron 104 and the second rotor back iron 204 into the first arc-shaped groove 1a and the second arc-shaped groove 1b of the sphere 1. The first rotor magnet 103 and the second rotor magnet 203 are respectively pasted onto the first rotor back iron 104 and the second rotor back iron 204 using epoxy glue. The inner and outer wall surfaces of the first rotor magnet 103 and the second rotor magnet 203 are designed as spherical surfaces and the side lengths of the magnet spherical surfaces are equal, with the aim that the magnets located at the bottom of the sphere 1 can be shared by the first rotor magnet 103 and the second rotor magnet 203.

[0029] On the outer surface of the sphere 1, a third arc-shaped groove 1c is machined for installing the first guide rail 105; a fourth arc-shaped groove 1d is machined for installing the second guide rail 205, and then the first guide rail 105 and the second guide rail 205 are fixed to the sphere 1 using screws. On each of the left and right sides of the first arc-shaped groove 1a, a third arc-shaped groove 1c is arranged; on each of the left and right sides of the second arc-shaped groove 1b, a fourth arc-shaped groove 1d is arranged. 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.

[0030] A bearing is installed inside the first guide wheel 107. The first guide wheel 107 is sleeved onto the first pin shaft 106, and the first pin shaft 106 with threads is installed on the side end face of the first housing 108. The first guide wheel 107 cooperates with the first guide rail 105 to limit the movement of the first guide rail 105 along the circular arc trajectory of the three first guide wheels 107, that is, to rotate around the X axis. Similarly, a bearing is installed inside the second guide wheel 207. The second guide wheel 207 is sleeved onto the second pin shaft 206, and the second pin shaft 206 with threads is installed on the side end face of the second housing 208. The second guide wheel 207 cooperates with the second guide rail 205 to limit the movement of the second guide rail 205 along the circular arc of the three second guide wheels 207, that is, to rotate around the Y axis.

[0031] At both ends of the first housing 108 of the first permanent magnet brushless DC motor 100, circular first boss wheel shafts 108a are designed, and the first boss wheel shafts 108a are sleeved with first bearings 306a; at both ends of the second housing 208 of the second permanent magnet brushless DC motor 200, circular second boss wheel shafts 208a are designed, and the second boss wheel shafts 208a are sleeved with second bearings 306b. The first bearings 306a and the second bearings 306b are installed in the inner wall holes of the rotor bracket 307. The weights of the sphere 1, the first permanent magnet brushless DC motor 100, and the second permanent magnet brushless DC motor 200 are supported by a total of four bearings, namely the first bearings 306a and the second bearings 306b.

[0032] The third permanent magnet brushless DC motor 300 further includes a first retaining ring 308, a second retaining ring 312, a crossed 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 inside the cavity of the third housing 311 and is limited in circumferential movement by the key 305 of the third stator core 302; the second retaining ring 312 is fixed to the third housing 311 using screws and is used to press 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 crossed roller bearing 309 is fixed to the third housing 311 using screws, and the inner ring of the crossed roller bearing 309, the first retaining ring 308, the rotor bracket 307, and the third rotor 320 are fixed together using screws.

[0033] On the upper and lower end faces of the rotor bracket 307, a first boss 307a and a second boss 307b are designed. A first lead hole 307c is designed on the first boss 307a for use as the lead wire outlet hole of the second stator winding 202; a second lead hole 307d is designed on the second boss 307b for use as the lead wire outlet hole of the first stator winding 102.

[0034] According to the design requirements and considering the wire winding problem generated during the full-circle rotation of the first permanent magnet brushless DC motor 100 and the second permanent magnet brushless DC motor 200, the power supply and communication problems can be solved by adopting the technology of wireless charging + wireless communication; or the first boss shaft 108a and the second boss shaft 208a adopt a hollow shaft solution, and the lead wires are led out from the hollow shaft to connect to the controller assembly and the battery; or the motion angle range of each motor is set on the host computer, and only perform a similar pendulum motion (±90°). The third permanent magnet brushless DC motor 300 is spatially arranged on the outermost periphery, without the wire winding problem. The third rotor can achieve full-circle rotation, and the third permanent magnet brushless DC motor 300 can be directly powered by the battery - controller.

[0035] The cooperation between the 12 first guide wheels 107 of the first permanent magnet brushless DC motor 100 and the first guide rail 105, and the cooperation between the 12 second guide wheels 207 of the second permanent magnet brushless DC motor 200 and the second guide rail 205 jointly support the weight of the sphere 1 and limit the displacement in the three directions of XYZ.

[0036] The crossed roller bearing 309 supports the weights of the first permanent magnet brushless DC motor 100, the second permanent magnet brushless DC motor 200, and the third rotor 320, and rotates integrally relative to the third stator 310.

[0037] The first stator 110 is fixed to the first housing 108 by screws. The relative rotation between the first stator 110 and the first rotor 120 is realized by the relative movement between the first guide rail 105 and the first guide wheels 107. The relative movement between the first guide rail 105 and the three first guide wheels 107 is specifically reflected as follows: The first guide rail 105 is fixed to the sphere 1, and the rotation of the first rotor 120 drives the sphere 1 and the second permanent magnet brushless DC motor 200 as a whole to rotate around the X axis.

[0038] Similarly, the second stator 210 is fixed to the second housing 208 by screws. The relative rotation between the second stator 210 and the second rotor 220 is realized by the relative movement between the second guide rail 205 and the second guide wheels 207. The relative movement between the second guide rail 205 and the three second guide wheels 207 is specifically reflected as follows: The second guide rail 205 is fixed to the sphere 1, and the rotation of the second rotor 220 drives the sphere 1 and the first permanent magnet brushless DC motor 100 as a whole to rotate around 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 integrally around the Z-axis.

[0040] Furthermore, it further includes a first controller assembly 130, a second controller assembly 230, and a third control assembly 313. Among them, 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 controller assembly 130 and the second controller assembly 230 are fixed to the end face of the rotor bracket 307 by screws and rotate together with the third rotor 320. The third control assembly 313 is used to control the third permanent magnet brushless DC motor 300. The third control assembly 313 is fixed to the bottom of the third housing 311 by screws and is directly powered by an external DC power supply.

[0041] The inner and outer wall surfaces of the first rotor magnet 103, the second rotor magnet 203, and the third rotor magnet 303 are designed as spherical surfaces. The first stator core 101, the second stator core 201, and the third stator core 302 use SMC material and are easy to be designed into spherical shapes. The inner and outer walls of the first stator core 101 and the second stator core 201 are designed as spherical surfaces, and the inner wall of the third stator core 302 is designed as a spherical surface.

[0042] An absolute position encoder is installed according to the design requirements and sleeved on the first boss camshaft 108a and the second boss camshaft 208a for position detection of the first permanent magnet brushless DC motor 100 and the second permanent magnet brushless DC motor 200. Similarly, an absolute position encoder is installed on the rotor of the 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 integrally around the Z-axis. The support of the third rotor 320 is realized by a crossed roller bearing 309.

[0044] 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 within the protection scope of the present invention.

Claims

1. A three-degree-of-freedom spherical joint motor module applied to a humanoid robot, characterized in that, Comprising: A sphere, a first permanent magnet brushless DC motor, a second permanent magnet brushless DC motor, and a third permanent magnet brushless DC motor; Wherein, 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 are arranged at a 90-degree angle 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; 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.

2. The three-degree-of-freedom spherical joint motor module applied to a humanoid robot according to claim 1, wherein: The first permanent magnet brushless DC motor includes a first stator, a first rotor, and a first housing. The first stator includes a first stator core and a first stator winding. The first rotor includes 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 includes a second stator core and a second stator winding. The second rotor includes 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 includes a third stator core and a third stator winding. The third rotor includes a third rotor magnet and a third rotor back iron.

3. The three-degree-of-freedom spherical joint motor module for a humanoid robot according to claim 2, wherein: The outer surface of the sphere has a first arc-shaped groove for installing the first rotor magnet and the first rotor back iron; the outer surface of the sphere has a second arc-shaped 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-shaped 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 as spherical surfaces and the side lengths of the magnetic steel spherical surfaces are equal; the outer surface of the sphere is provided with a third arc-shaped groove for installing the first guide rail; the outer surface of the sphere is provided with a fourth arc-shaped groove for installing the second guide rail. Then the first guide rail and the second guide rail are fixed to the sphere. One third arc-shaped groove is arranged on each of the left and right sides of the first arc-shaped groove; one fourth arc-shaped groove is arranged on each of the left and right sides of the second arc-shaped groove. The plane where the first arc-shaped groove is located is perpendicular to the plane where the second arc-shaped groove is located in space.

4. The three-degree-of-freedom spherical joint motor module applied to a humanoid robot according to claim 3, wherein: A bearing is installed inside the first guide wheel. The first guide wheel is sleeved on the first pin shaft, and the first pin shaft is installed on the side end face of the first housing. The first guide wheel cooperates with the first guide rail to limit the first guide rail to move along the arc track of the first guide wheel, that is, to rotate around the X-axis; a bearing is installed inside the second guide wheel. The second guide wheel is sleeved on the second pin shaft, and the second pin shaft is installed on the side end face of the second housing. The second guide wheel cooperates with the second guide rail to limit the second guide rail to make an arc movement along the second guide wheel, that is, to rotate around the Y-axis.

5. The three-degree-of-freedom spherical joint motor module for a humanoid robot according to claim 4, characterized in that: The two ends of the first housing of the first permanent magnet brushless DC motor are provided with first boss axles, and the first boss axles are sleeved on the first bearings; the two ends of the second housing of the second permanent magnet brushless DC motor are provided with second boss axles, and the second boss axles are sleeved on the second bearings. The first bearing and the second bearing are installed in the inner wall holes of the rotor bracket of the third permanent magnet brushless DC motor, and the weights of the sphere, the first permanent magnet brushless DC motor and the second permanent magnet brushless DC motor are supported by the first bearing and the second bearing.

6. The three-degree-of-freedom spherical joint motor module applied to a humanoid robot according to claim 2, wherein: The third permanent magnet brushless DC motor further includes a first retaining ring, a second retaining ring, a crossed roller bearing and a rotor bracket; the third stator is placed inside the cavity of the third housing and is circumferentially limited by a key; the second retaining ring is fixed to the third housing for pressing the third stator; the outer ring of the crossed roller bearing is fixed to the third housing, and the inner ring of the crossed roller bearing, the first retaining ring, the rotor bracket and the third rotor are fixed together.

7. The three-degree-of-freedom spherical joint motor module applied to a humanoid robot according to claim 6, wherein: The rotor bracket is designed with a first boss and a second boss on the upper and lower end faces. A first lead hole is designed on the first boss for use as an outlet hole for the lead wire of the second stator winding; a second lead hole is designed on the second boss for use as an outlet hole for the lead wire of the first stator winding.

8. The three-degree-of-freedom spherical joint motor module applied to a humanoid robot according to claim 6, wherein: The crossed roller bearing supports the weights 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.

9. The three-degree-of-freedom spherical joint motor module applied to a humanoid robot according to claim 8, wherein: The first stator is fixed to the first housing, and the relative rotation between the first stator and the first rotor is realized by the relative movement between the first guide rail and the first guide wheel. The first guide rail is fixed to the sphere, and the rotation of the first rotor drives the sphere and the second permanent magnet brushless DC motor as a whole to rotate around the X axis; The second stator is fixed to the second housing, and the relative rotation between the second stator and the second rotor is realized by the relative movement between the second guide rail and the second guide wheel. The second guide rail is fixed to the sphere, and the rotation of the second rotor drives the sphere and the first permanent magnet brushless DC motor as a whole to rotate 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 as a whole to rotate around the Z axis.

10. The three-degree-of-freedom spherical joint motor module applied to a humanoid robot according to claim 4, characterized in that: It further 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 brushless DC motor and includes a first controller and a first battery; the second controller component is used to control the second permanent magnet brushless DC 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 together with the third rotor. The third control component is used to control the third permanent magnet brushless DC 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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