A multi-degree-of-freedom spherical electric joint

Abstract

The present invention relates to the technical field of spherical joints, and discloses a multi-degree-of-freedom spherical electric joint, which includes a first rotor, a second rotor, a third rotor, an output shaft, a first stator, a second stator, a third stator and a base. The first rotor, the second rotor and the third rotor are respectively in an annular shape and have the same center of circle. The first rotor and the second rotor are cross-arranged to form a spherical frame. The third rotor is arranged inside the spherical frame. A connecting shaft is arranged inside the third rotor. 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. The first stator is rotatably connected to the base and its rotation axis is the first axis, and the first rotor can rotate following the first stator. The second stator is rotatably connected to the base and its rotation axis is the second axis, and the second rotor can rotate following the second stator. The third stator is fixedly connected to the base. The present invention decouples the three-degree-of-freedom motion of the joint, has simple control, and improves the output torque.

Description

Technical Field

[0001] The present invention relates to the technical field of spherical joints, and particularly to a multi-degree-of-freedom spherical electric joint. Background Art

[0002] For existing robots to achieve rotational motion with three degrees of freedom, one approach is to connect multiple single-degree-of-freedom joints in series, and each joint also has a reducer inside. However, this solution has problems such as large self-weight, poor dynamic performance, return error, and singularities in the working space; another approach is to use a multi-degree-of-freedom spherical electric joint, which can generate rotational motion with multiple degrees of freedom at a single joint. The general method is to use a spherical motor, which consists of a single spherical stator and a single spherical rotor and can achieve rotational motion in three directions simultaneously. The position detection of the rotor is realized through contact measurement methods, Hall element measurement methods, photoelectric measurement methods, vision measurement methods, etc. Among them, the contact measurement method connects the joint output shaft with an encoder through mechanisms such as mechanical linkages and slides, so as to calculate the pose of the joint output shaft; the Hall element measurement method arranges Hall elements on the stator and uses the rotor magnetic field to measure the pose; the photoelectric measurement method analyzes the texture on the rotor surface to estimate the rotor pose; the vision measurement method requires color coding on the rotor and uses the images collected by a camera to solve the coding combination in the image to obtain the rotor pose.

[0003] However, the existing spherical motors have the following problems: 1. Too small torque density: In a spherical motor, the permanent magnet type spherical motor has the largest torque. However, due to the high coupling of the rotor's rotational motion in all directions, during the rotation in one direction, the torque in another direction will be affected, and the electromagnetic force cannot be fully utilized, so the torque density is still very small; 2. Lack of a high-precision integration solution for rotor attitude detection: The contact measurement method has high precision, but it requires additional transmission mechanisms, which will increase the rotor inertia and reduce the dynamic performance; the Hall element measurement method is easily affected by the magnetic field and has slightly poor detection accuracy; the photoelectric measurement method is affected by ambient light and has low precision; the vision measurement method has a large system and is not convenient for integration. The above four detection methods are limited by their respective limitations and are difficult to be integrated on the joint; 3. Difficult to control: Due to severe motion coupling, the control method is relatively complex. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a multi-degree-of-freedom spherical electric joint that uses a frame structure to decouple the three-degree-of-freedom motion of the joint and greatly improves the output rotational torque. To solve the above technical problem, the present invention provides a multi-degree-of-freedom spherical electric joint, including a first rotor, a second rotor, a third rotor, an output shaft, a first stator, a second stator, a third stator and a base. The first rotor, the second rotor and the third rotor are respectively in an annular shape. The first rotor, the second rotor and the third rotor have the same center of the circle. The first rotor and the second rotor are cross-arranged to form a spherical frame. The third rotor is arranged inside the spherical frame. A connecting shaft arranged along the radial direction of the third rotor is provided inside the third rotor. The output shaft is arranged along the radial directions of the first rotor and the second rotor. The output shaft passes through the cross-junction of the first rotor and the second rotor. The output shaft is connected to the connecting shaft through a universal joint. The first stator and the first rotor cooperate to form a first driving unit. The first stator is rotatably connected to the base and its rotation axis is the first axis. The first axis is arranged along the radial direction of the first rotor. The first rotor can rotate around the first axis following the first stator. The second stator and the second rotor cooperate to form a second driving unit. The second stator is rotatably connected to the base and its rotation axis is the second axis. The second axis is arranged along the radial direction of the second rotor. The second rotor can rotate around the second axis following the second stator. The third stator and the third rotor cooperate to form a third driving unit. The third stator is fixedly connected to the base. The third rotor can rotate around its own axis.

[0005] As a preferred solution of the present invention, the universal joint includes a connecting piece and a connecting sleeve. The output shaft is connected to the connecting piece. The connecting sleeve is rotatably sleeved on the connecting shaft. The connecting piece is rotatably connected to the connecting sleeve and its rotation axis intersects with the axis of the connecting shaft at the center of the sphere of the third rotor.

[0006] As a preferred solution of the present invention, a first permanent magnet array is provided on the outer side of the first rotor. The first stator is provided with a first winding corresponding to the first permanent magnet array. After the first winding is energized, a magnetic field is generated to drive the first rotor to rotate around the axis of the first rotor. A second permanent magnet array is provided on the outer side of the second rotor. The second stator is provided with a second winding corresponding to the second permanent magnet array. After the second winding is energized, a magnetic field is generated to drive the second rotor to rotate around the axis of the second rotor. A third permanent magnet array is provided on the outer side of the third rotor. The third stator is provided with a third winding corresponding to the third permanent magnet array. After the third winding is energized, a magnetic field is generated to drive the third rotor to rotate around the axis of the third rotor.

[0007] As a preferred embodiment of the present invention, a first magnetic encoder for detecting the rotational position of the first stator is provided at the rotational connection between the first stator and the base, and a second magnetic encoder for detecting the rotational position of the second stator is provided at the rotational connection between the second stator and the base.

[0008] As a preferred embodiment of the present invention, a positioning shaft coaxial with the output shaft is provided at the bottom of the universal joint. The positioning shaft passes through the bottoms of the first rotor and the second rotor, and a third magnetic encoder for detecting the rotational position of the positioning shaft is provided at the bottom of the positioning shaft.

[0009] As a preferred embodiment of the present invention, two first stators are provided, and the two first stators are respectively located on the radial two sides of the first rotor.

[0010] As a preferred embodiment of the present invention, two second stators are provided, and the two second stators are respectively located on the radial two sides of the second rotor.

[0011] As a preferred embodiment of the present invention, the axis of the third rotor is vertically arranged.

[0012] As a preferred embodiment of the present invention, a protrusion is provided at the top of the first rotor, a groove is provided at the top of the second rotor, the protrusion is arranged on the groove, and the output shaft sequentially passes through the protrusion and the groove.

[0013] Compared with the prior art, the beneficial effects of a multi-degree-of-freedom spherical electric joint implemented by the present invention are as follows: When the first driving unit drives the first rotor to rotate, under the action of the first stator, the second rotor and the second stator, finally the first rotor rotates around the second axis, thereby driving the output shaft to rotate around the second axis; When the second driving unit drives the second rotor to rotate, under the action of the second stator, the first rotor and the first stator, finally the second rotor rotates around the first axis, thereby driving the output shaft to rotate around the first axis; When the third driving unit drives the third rotor to rotate, under the action of the universal joint, finally the output shaft rotates around its own axis; The output shaft of the present invention can rotate around the first axis, the second axis and its own axis respectively, realizing the multi-degree-of-freedom rotation of the output shaft, decoupling the three-degree-of-freedom motion, with simple control, high torque density, small inertia, good dynamic performance, greatly improving the output torque, removing internal materials, and greatly reducing the self-weight of the joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a structural diagram of a multi-degree-of-freedom spherical electric joint provided by the present invention;

[0015] Figure 2 is Figure 1 a structural diagram from another angle of

[0016] Figure 3 Yes Figure 1 Structural diagram of the output shaft in [device] connected to the connecting shaft through a universal joint;

[0017] In the figure, 1 is the first rotor; 11 is the first permanent magnet array; 12 is the protrusion; 2 is the second rotor; 21 is the second permanent magnet array; 22 is the groove; 3 is the third rotor; 31 is the connecting shaft; 32 is the third permanent magnet array; 4 is the output shaft; 41 is the universal joint; 411 is the connecting part; 412 is the connecting sleeve; 413 is the positioning shaft; 5 is the first stator; 51 is the first axis; 52 is the first winding; 53 is the first magnetic encoder; 6 is the second stator; 61 is the second axis; 62 is the second winding; 63 is the second magnetic encoder; 7 is the third stator; 71 is the third winding; 72 is the third magnetic encoder; 8 is the base. Detailed implementation manners

[0018] The following combines the drawings and embodiments to further describe in detail the specific implementation manners of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0019] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. in the present invention is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0020] As Figures 1 to 3 shown, for the convenience of explaining its working mechanism, Figure 1Only some of the support structures and the core electromagnetic drive components are simply shown. A multi-degree-of-freedom spherical electric joint according to a preferred embodiment of the present invention includes a first rotor 1, a second rotor 2, a third rotor 3, an output shaft 4, a first stator 5, a second stator 6, a third stator 7, and a base 8. The first rotor 1, the second rotor 2, and the third rotor 3 are respectively in an annular shape. The first rotor 1, the second rotor 2, and the third rotor 3 have the same center of the circle. The first rotor 1 and the second rotor 2 are cross-arranged to form a spherical frame. The third rotor 3 is arranged inside the spherical frame. A connecting shaft 31 is arranged radially along the third rotor 3 on the inner side of the third rotor 3. The output shaft 4 is arranged radially along the first rotor 1 and the second rotor 2. The output shaft 4 passes through the cross-connection of the first rotor 1 and the second rotor 2. The output shaft 4 is connected to the connecting shaft 31 through a universal joint 41. The first stator 5 and the first rotor 1 cooperate to form a first drive unit. The first stator 5 is rotatably connected to the base 8 and its rotation axis is the first axis 51. The first axis 51 is arranged radially along the first rotor 1. The first rotor 1 can rotate around the first axis 51 following the first stator 5 (under the action of the magnetic attraction force between the first stator 5 and the first rotor 1). The second stator 6 and the second rotor 2 cooperate to form a second drive unit. The second stator 6 is rotatably connected to the base 8 and its rotation axis is the second axis 61. The second axis 61 is arranged radially along the second rotor 2. The second rotor 2 can rotate around the second axis 61 following the second stator 6 (under the action of the magnetic attraction force between the second stator 6 and the second rotor 2). The third stator 7 and the third rotor 3 cooperate to form a third drive unit. The third stator 7 is fixedly connected to the base 8. The third rotor 3 can rotate around its own axis. The universal joint 41 can transfer the rotation of the connecting shaft 31 around the axis of the third rotor 3 to the rotation of the output shaft 4 around its own axis. At the same time, the universal joint 41 can also prevent the rotation of the first rotor 1 and the rotation of the second rotor 2 from interfering with the third rotor 3.

[0021] The working principle of this embodiment is as follows: When the first driving unit drives the first rotor 1 to rotate, specifically, the windings of the first stator 5 are energized to generate a magnetic field that drives the first rotor 1 to rotate around the axis of the first rotor 1. Since the output shaft 4 passes through the intersection of the first rotor 1 and the second rotor 2, and the second rotor 2 can rotate around the second axis 61 following the second stator 6, the first stator 5 drives the first rotor 1 to rotate, thereby driving the second rotor 2 to rotate. At the same time, under the adsorption effect between the second stator 6 and the second rotor 2, finally, the second rotor 2 and the second stator 6 rotate around the second axis 61, thereby driving the output shaft 4 to rotate around the second axis 61. When the second driving unit drives the second rotor 2 to rotate, specifically, the windings of the second stator 6 are energized to generate a magnetic field that drives the second rotor 2 to rotate around the axis of the second rotor 2. Similarly, the second stator 6 drives the second rotor 2 to rotate, thereby driving the first rotor 1 to rotate. At the same time, under the adsorption effect between the first stator 5 and the first rotor 1, finally, the first rotor 1 and the first stator 5 rotate around the first axis 51, thereby driving the output shaft 4 to rotate around the first axis 51. When the third driving unit drives the third rotor 3 to rotate, specifically, the windings of the third stator 7 are energized to generate a magnetic field that drives the third rotor 3 to rotate around the axis of the third rotor 3. Since the output shaft 4 is connected to the connecting shaft 31 through the universal joint 41, finally, under the action of the universal joint 41, the output shaft 4 rotates around its own axis. The output shaft 4 of the present invention can rotate around the first axis 51, the second axis 61, and its own axis respectively, realizing the multi-degree-of-freedom rotation of the output shaft 4. That is, without considering the limit, the output shaft 4 can freely rotate on a sphere with the length of itself as the radius and the center of the first rotor 1 as the center of the sphere, and can also rotate self. It decouples the three-degree-of-freedom motion, has simple control, high torque density, small inertia, good dynamic performance, greatly improves the output torque, removes the internal material, and greatly reduces the self-weight of the joint.

[0022] Exemplarily, the universal joint 41 includes a connecting member 411 and a connecting sleeve 412. The output shaft 4 is connected to the connecting member 411. In this embodiment, the bottom end of the output shaft 4 is fixedly connected to the top of the connecting member 411. The connecting sleeve 412 is rotatably sleeved on the connecting shaft 31, that is, the connecting sleeve 412 can rotate around the axis of the connecting shaft 31. The connecting member 411 is rotatably connected to the connecting sleeve 412, and its rotation axis intersects with the axis of the connecting shaft 31 at the center of the sphere of the third rotor 3. When the first driving unit drives the output shaft 4 to rotate around the second axis 61, the connecting sleeve 412 rotates relative to the connecting shaft 31. When the second driving unit drives the output shaft 4 to rotate around the first axis 51, the connecting member 411 rotates relative to the connecting sleeve 412, thereby preventing the connecting shaft 31 from following the rotation and ensuring that the connecting shaft 31 does not drive the third rotor 3 to move and cause it to be misaligned with the third stator 7.

[0023] Exemplarily, a first permanent magnet array 11 is provided on the outer side of the first rotor 1, and the first stator 5 is provided with a first winding 52 corresponding to the first permanent magnet array 11. After the first winding 52 is energized, a magnetic field is generated to drive the first rotor 1 to rotate around the axis of the first rotor 1. The structure of the first winding 52 and the arrangement structure of the first permanent magnet array 11 are mature technologies in the motor and will not be described in detail here. A second permanent magnet array 21 is provided on the outer side of the second rotor 2, and the second stator 6 is provided with a second winding 62 corresponding to the second permanent magnet array 21. After the second winding 62 is energized, a magnetic field is generated to drive the second rotor 2 to rotate around the axis of the second rotor 2; a third permanent magnet array 32 is provided on the outer side of the third rotor 3, and the third stator 7 is provided with a third winding 71 corresponding to the third permanent magnet array 32. After the third winding 71 is energized, a magnetic field is generated to drive the third rotor 3 to rotate around the axis of the third rotor 3. Multiple third stators 7 can be provided, as long as the third windings 71 are distributed around the axis of the third rotor 3, or the third stator 7 is a ring coaxially arranged with the third rotor 3, and the third winding 71 is arranged in a circle around the inner circle of the third stator 7.

[0024] Exemplarily, two first stators 5 are provided. The two first stators 5 are respectively located on the radial two sides of the first rotor 1, and the two first stators 5 are respectively rotatably connected to the base 8. At this time, the two first stators 5 are distributed on both sides of the first rotor 1 along the first axis 51.

[0025] Exemplarily, two second stators 6 are provided. The two second stators 6 are respectively located on the radial two sides of the second rotor 2.

[0026] Exemplarily, a first magnetic encoder 53 for detecting the rotational position of the first stator 5 is provided at the rotational connection between the first stator 5 and the base 8, so as to determine the rotational position of the first rotor 1. Generally, the outer side of the first stator 5 is rotatably connected to the base 8 through a first rotating shaft, and the first magnetic encoder 53 is installed at the connection between the first rotating shaft and the base 8. A second magnetic encoder 63 for detecting the rotational position of the second stator 6 is provided at the rotational connection between the second stator 6 and the base 8, so as to determine the rotational position of the second rotor 2. Generally, the outer side of the second stator 6 is rotatably connected to the base 8 through a second rotating shaft, and the second magnetic encoder 63 is installed at the connection between the second rotating shaft and the base 8.

[0027] Exemplarily, a positioning shaft 413 coaxial with the output shaft 4 is provided at the bottom of the universal joint 41. The positioning shaft 413 passes through the bottoms of the first rotor 1 and the second rotor 2. A third magnetic encoder 72 for detecting the rotational position of the positioning shaft 413 is provided at the bottom of the positioning shaft 413. By detecting the rotational position of the positioning shaft 413, the rotational position of the output shaft 4 is determined. In this embodiment, for the convenience of installing the third magnetic encoder 72, a first boss is provided at the bottom of the first rotor 1, and a second boss is provided at the bottom of the second rotor 2. The first boss is located above the second boss. The positioning shaft 413 passes through the first boss and the second boss in sequence, and the third magnetic encoder 72 is installed at the bottom of the second boss.

[0028] Exemplarily, the axis of the third rotor 3 is vertically arranged, that is, the third rotor 3 is horizontally arranged, which is convenient for the arrangement of the third rotor 3 and the base 8. In this embodiment, the base 8 is a ring coaxial with the third rotor 3. The third stator 7 is arranged between the inner side of the base 8 and the third rotor 3. The base 8 is provided with a first installation groove for installing the first rotor 1 and a second installation groove for installing the second rotor 2 for positioning and installation.

[0029] In an embodiment of the present invention, in the initial state, the axis of the first rotor 1 and the second axis 61 are arranged along the X-axis, the axis of the second rotor 2 and the first axis 51 are arranged along the Y-axis, and the axis of the third rotor 3 and the axis of the output shaft 4 are arranged along the Z-axis. The X-axis, Y-axis, and Z-axis are perpendicular to each other in pairs. It should be noted that the above positions are the initial positions of the present invention and do not mean that the above position relationship will be maintained subsequently. In fact, when the first rotor 1, the second rotor 2, and the output shaft 4 rotate, the corresponding axes will change in position, while the first axis 51, the second axis 61, and the axis of the third rotor 3 remain unchanged.

[0030] Exemplarily, a protrusion 12 is provided at the top of the first rotor 1, and a groove 22 is provided at the top of the second rotor 2. The protrusion 12 is arranged on the groove 22. The output shaft 4 passes through the protrusion 12 and the groove 22 in sequence to facilitate the cross arrangement of the first rotor 1 and the second rotor 2.

[0031] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and replacements can be made, and these improvements and replacements should also be regarded as the protection scope of the present invention.

Claims

1. A multi-degree-of-freedom spherical electric joint, characterized in that: It includes a first rotor, a second rotor, a third rotor, an output shaft, a first stator, a second stator, a third stator and a base. The first rotor, the second rotor and the third rotor are respectively in an annular shape. The first rotor, the second rotor and the third rotor have the same center of circle. The first rotor and the second rotor are cross - arranged to form a spherical frame. The third rotor is arranged inside the spherical frame. A connecting shaft is arranged on the inner side of the third rotor along the radial direction of the third rotor. The output shaft is arranged along the radial directions of the first rotor and the second rotor. 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. The universal joint includes a connecting piece and a connecting sleeve. The output shaft is connected to the connecting piece. The connecting sleeve is rotatably sleeved on the connecting shaft. The connecting piece is rotatably connected to the connecting sleeve and its rotation axis intersects with the axis of the connecting shaft at the center of the sphere of the third rotor. The first stator and the first rotor cooperate to form a first driving unit. The first stator is rotatably connected to the base and its rotation axis is the first axis. The first axis is arranged along the radial direction of the first rotor. The first rotor can follow the first stator to rotate around the first axis. The second stator and the second rotor cooperate to form a second driving unit. The second stator is rotatably connected to the base and its rotation axis is the second axis. The second axis is arranged along the radial direction of the second rotor. The second rotor can follow the second stator to rotate around the second axis. The third stator and the third rotor cooperate to form a third driving unit. The third stator is fixedly connected to the base. The third rotor can rotate around its own axis.

2. The multi - degree - of - freedom spherical electric joint according to claim 1, characterized in that: A first permanent - magnet array is arranged on the outer side of the first rotor. The first stator is provided with a first winding corresponding to the first permanent - magnet array. After the first winding is energized, a magnetic field is generated to drive the first rotor to rotate around the axis of the first rotor. A second permanent - magnet array is arranged on the outer side of the second rotor. The second stator is provided with a second winding corresponding to the second permanent - magnet array. After the second winding is energized, a magnetic field is generated to drive the second rotor to rotate around the axis of the second rotor. A third permanent - magnet array is arranged on the outer side of the third rotor. The third stator is provided with a third winding corresponding to the third permanent - magnet array. After the third winding is energized, a magnetic field is generated to drive the third rotor to rotate around the axis of the third rotor.

3. The multi - degree - of - freedom spherical electric joint according to claim 1, characterized in that: A first magnetic encoder for detecting the rotation position of the first stator is arranged at the rotation connection of the first stator and the base. A second magnetic encoder for detecting the rotation position of the second stator is arranged at the rotation connection of the second stator and the base.

4. The multi - degree - of - freedom spherical electric joint according to claim 1, It is characterized in that: A positioning shaft coaxial with the output shaft is provided at the bottom of the universal joint. The positioning shaft passes through the bottoms of the first rotor and the second rotor, and a third magnetic encoder for detecting the rotational position of the positioning shaft is provided at the bottom of the positioning shaft.

5. The multi-degree-of-freedom spherical electric joint according to claim 1, It is characterized in that: Two first stators are provided, and the two first stators are respectively located on the radial two sides of the first rotor.

6. The multi-degree-of-freedom spherical electric joint according to claim 1, It is characterized in that: Two second stators are provided, and the two second stators are respectively located on the radial two sides of the second rotor.

7. The multi-degree-of-freedom spherical electric joint according to claim 1, It is characterized in that: The axis of the third rotor is vertically arranged.

8. The multi-degree-of-freedom spherical electric joint according to claim 1, It is characterized in that: A protrusion is provided at the top of the first rotor, a groove is provided at the top of the second rotor, the protrusion is arranged on the groove, and the output shaft sequentially passes through the protrusion and the groove.

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