Spherical joint motion control method, spherical joint and motion system

Abstract

The invention discloses a spherical joint motion control method, a spherical joint and a motion system.The spherical joint is used for controlling motion of the spherical joint, the spherical joint comprises a fixed spherical shell, a rotary table spherical shell, an output spherical shell and an output disc, and the rotary table spherical shell is arranged on the fixed spherical shell and can rotate around a first axis; the output spherical shell is arranged on the rotary table spherical shell and can rotate around a second axis, and the output disc is arranged on the output spherical shell and can rotate around a third axis; the motion control method comprises the following steps: acquiring a pose of an output disc, wherein the pose comprises coordinates and a rotation angle of the output disc; the rotation angles of the output spherical shell and the rotary table spherical shell are solved according to the geometric structure of the spherical joint and the coordinates of the output disc; and solving the rotation angle of the corresponding motor according to the rotation angle of the output disc, the rotation angle of the output spherical shell and the rotation angle of the rotary table spherical shell by adopting inverse kinematics. The technical effects that inverse kinematics analysis is carried out on the spherical joint, and the motor rotation angle solving efficiency is improved are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of motion joint control, and in particular, to a spherical joint motion control method, a spherical joint, and a motion system. Background Art

[0002] In a multi-dimensional motion environment, it is necessary to configure a multi-degree-of-freedom joint structure for a motion device. For example, in the motion of a robotic arm, it is necessary to provide a three-degree-of-freedom motion joint to connect multiple robotic arms, and the motion joint provides multi-dimensional motion for the robotic arm. In a camera pan-tilt device, it is also necessary to provide multi-dimensional motion through a motion joint to ensure the smoothness of the camera during motion.

[0003] The motion control of a three-degree-of-freedom spherical joint includes calculating the rotation angle of the corresponding motor according to the pose of the end. Currently, the motion control method is relatively complex and the solution efficiency is not high. Summary of the Invention

[0004] The main object of the present invention is to provide a spherical joint motion control method, a spherical joint, and a motion system to solve the problem that the motion control of the spherical joint in the related art is relatively complex and the solution efficiency is not high.

[0005] To achieve the above object, the present invention provides a spherical joint motion control method for controlling the motion of a spherical joint. The spherical joint includes: a fixed spherical shell, a rotating spherical shell, an output spherical shell, and an output disk. The rotating spherical shell is arranged on the fixed spherical shell and can rotate around a first axis. The output spherical shell is arranged on the rotating spherical shell and can rotate around a second axis. The output disk is arranged on the output spherical shell and can rotate around a third axis;

[0006] The motion control method includes:

[0007] Obtain the pose of the output disk in the base coordinate system. The pose includes the coordinates and rotation angle of the output disk. The base coordinate system is a coordinate system established with the first axis as the coordinate axis and the intersection position of the second axis and the first axis as the origin;

[0008] Solve the rotation angles of the output spherical shell and the rotating spherical shell according to the geometric structure of the spherical joint and the coordinates of the output disk;

[0009] Adopt inverse kinematics to solve the rotation angles of the corresponding motors according to the rotation angle of the output disk, the rotation angle of the output spherical shell, and the rotation angle of the rotating spherical shell.

[0010] Further, the first axis is located on the z-axis of the base coordinate system, the included angle between the second axis and the xoy plane in the base coordinate system is θ, 0° ≤ θ ≤ 90°, and the rotation angle j2 of the output spherical shell is calculated by the following formula:

[0011]

[0012] The rotation angle j1 of the rotating billiard ball shell is calculated using the following formula:

[0013]

[0014] Where, R is the radius of the rotating billiard ball shell, the coordinates of the key point on the output disk in the base coordinate system are (x, y, z), the base coordinate system is a coordinate system established with the first axis as the coordinate axis and the intersection position of the second axis and the first axis as the origin, L1 is the length of OA, L1 is the length of AB, point B is the key point on the output disk, point O is the origin of the base coordinate system, and point A is the foot of the perpendicular from point B on the second axis.

[0015] Further, the angle θ between the second axis and the xoy plane in the base coordinate system is 45°.

[0016] Further, the key point is the rotation center of the output disk.

[0017] Further, using inverse kinematics, the rotation angles of the corresponding motors are solved according to the rotation angle of the output disk, the rotation angle of the output ball shell, and the rotation angle of the rotating billiard ball shell, including:

[0018] Calculating the rotation angle of the motor corresponding to the rotating billiard ball shell according to the reduction ratio of the rotating billiard ball shell to the corresponding motor and the rotation angle of the rotating billiard ball shell;

[0019] Calculating the rotation angle of the motor corresponding to the output ball shell according to the rotation angle of the rotating billiard ball shell, the reduction ratio of the output ball shell to the corresponding motor, the rotation angle of the output ball shell, and the end gear ratio of the output ball shell;

[0020] Calculating the rotation angle of the motor corresponding to the output disk according to the rotation angle of the rotating billiard ball shell, the rotation angle of the output ball shell, the reduction ratio of the output disk to the corresponding motor, the end gear ratio of the output disk, the two-stage end gear ratio of the output disk, and the rotation angle of the output disk.

[0021] Further, the rotation angle m1 of the motor corresponding to the rotating billiard ball shell is calculated using the following formula:

[0022]

[0023] The rotation angle m2 of the motor corresponding to the output ball shell is calculated using the following formula:

[0024]

[0025] The rotation angle m3 of the motor corresponding to the output disk is calculated using the following formula:

[0026]

[0027] j 1_reduction_ratio : Reduction ratio of the rotating ball shell to the corresponding motor;

[0028] j 2_raduction_ratio : Reduction ratio of the output ball shell to the corresponding motor:

[0029] j 3_reduction_ratio : Reduction ratio of the output disk to the corresponding motor:

[0030] j 2_gear_ratio : Gear ratio at the end of the output ball shell:

[0031] j 3_gear_ratio : Gear ratio at the end of the output disk:

[0032] j 3_two_stage_gear_ratio : Two-stage gear reduction ratio at the end of the output disk.

[0033] According to another aspect of the present invention, there is provided a spherical joint, which is controlled by the above control method. The spherical joint includes:

[0034] A base, the base includes a fixed ball shell;

[0035] A motor frame, the motor frame is arranged inside the fixed ball shell, and a first driving motor, a second driving motor and a third driving motor are arranged on the motor frame;

[0036] A rotating ball shell, the rotating ball shell is opposite to the fixed ball shell and encloses a spherical space, and the rotating ball shell can rotate around a first axis;

[0037] A first transmission structure, the first transmission structure is arranged inside the spherical space, and the first driving motor drives the rotating ball shell to rotate around the first axis through the first transmission structure;

[0038] An output ball shell, the output ball shell is arranged on the rotating ball shell and can rotate around a second axis;

[0039] A second transmission structure, the second transmission structure is arranged inside the spherical space, and the second driving motor drives the output ball shell to rotate around the second axis through the second transmission structure;

[0040] An output disk, the output disk is arranged on the output ball shell and can rotate around a third axis;

[0041] A third transmission structure, a part of the third transmission structure is located inside the spherical space, and another part is located outside the rotating ball shell. The third driving motor drives the output disk to rotate around the third axis through the third transmission structure.

[0042] Furthermore, the first transmission structure, the second transmission structure, and the third transmission structure are all gear transmission structures.

[0043] Furthermore, the first drive motor, the second drive motor, and the third drive motor are arranged circumferentially.

[0044] According to another aspect of the present invention, a motion system is provided, including a spherical joint and a control module, and the control module is configured to execute the above control method.

[0045] In an embodiment of the present invention, by obtaining the pose of the output disk, the pose includes the coordinates and the rotation angle j3 of the output disk; according to the geometric structure of the spherical joint and the coordinates of the output disk, the rotation angles of the output spherical shell and the rotating ball shell are solved; by using inverse kinematics, according to the rotation angle of the output disk, the rotation angle of the output spherical shell, and the rotation angle of the rotating ball shell, the rotation angles of the corresponding motors are solved, achieving the technical effect of performing inverse kinematics analysis on the spherical joint and improving the solving efficiency of the motor rotation angles, and further solving the problem that the motion control of the spherical joint in the related art is relatively complex and the solving efficiency is not high. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention, making other features, objects, and advantages of the present invention more obvious. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0047] Figure 1 is a schematic diagram of the external structure of the spherical joint according to an embodiment of the present invention;

[0048] Figure 2 is a schematic diagram of the layout structure of the motor bracket and the drive motor of the spherical joint according to an embodiment of the present invention;

[0049] Figure 3 is a schematic diagram of one of the sectional structures of the spherical joint according to an embodiment of the present invention;

[0050] Figure 4 is a schematic diagram of one of the sectional structures of the spherical joint according to an embodiment of the present invention;

[0051] Figure 5 is a schematic diagram of one of the sectional structures of the spherical joint according to an embodiment of the present invention;

[0052] Figure 6 is a schematic diagram of one of the sectional structures of the spherical joint according to an embodiment of the present invention;

[0053] Figure 7It is a schematic diagram of different actions of a spherical joint in an embodiment of the present invention;

[0054] Figure 8 It is a schematic diagram of a spherical joint motion control method in an embodiment of the present invention;

[0055] Among them, 1 is the base, 101 is the fixed spherical shell, 2 is the rotating ball shell, 3 is the output spherical shell, 4 is the output disk, 5 is the motor bracket, 6 is the first driving motor, 7 is the second driving motor, 8 is the third driving motor, 9 is the first shaft body, 10 is the first bearing, 11 is the second bearing, 12 is the spherical space, 13 is the first transmission structure, 130 is the first gear, 131 is the spherical shell gear ring, 14 is the second transmission structure, 140 is the second gear, 141 is the third gear, 1410 is the straight tooth section, 1411 is the bevel tooth section, 142 is the fourth gear, 15 is the third transmission structure, 150 is the fifth gear, 151 is the sixth gear, 1510 is the transmission lower tooth, 1511 is the transmission upper tooth, 152 is the seventh gear, 1520 is the transmission inner tooth, 1521 is the transmission outer tooth, 153 is the eighth gear, 1530 is the arc-shaped disk, 1531 is the connecting protrusion, 16 is the second shaft body, 17 is the third shaft body. Detailed implementation manners

[0056] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0057] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so as to describe the embodiments of the present invention here.

[0058] In the present invention, the orientation or positional relationship indicated by terms such as "upper", "lower", "inner", etc. is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit that the indicated device, element or component must have a specific orientation, or be constructed and operated in a specific orientation.

[0059] Moreover, in addition to being able to represent an orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0060] In addition, terms such as "arranged", "provided with", "connected", "fixed", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there can be internal communication between two devices, components or parts. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] In addition, the meaning of the term "a plurality of" should be two or more.

[0062] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0063] As Figures 1 to 4 shown, an embodiment of the present invention provides a spherical joint, including:

[0064] A base 1, the base 1 includes a fixed spherical shell 101;

[0065] A motor frame 5, the motor frame 5 is arranged inside the fixed spherical shell 101, and a first driving motor 6, a second driving motor 7 and a third driving motor 8 are arranged on the motor frame 5;

[0066] A rotating spherical shell 2, the rotating spherical shell 2 is opposite to the fixed spherical shell 101 and encloses a spherical space 12, and the rotating spherical shell 2 can rotate around a first axis;

[0067] A first transmission structure 13, the first transmission structure 13 is arranged inside the spherical space 12, and the first driving motor 6 drives the rotating spherical shell 2 to rotate around the first axis through the first transmission structure 13;

[0068] An output spherical shell 3, the output spherical shell 3 is arranged on the rotating spherical shell 2 and can rotate around a second axis, and the second axis is not collinear with the first axis;

[0069] A second transmission structure 14, the second transmission structure 14 is arranged inside the spherical space 12, and the second driving motor 7 drives the output spherical shell 3 to rotate around the second axis through the second transmission structure 14;

[0070] An output disk 4, the output disk 4 is arranged on the output spherical shell 3 and can rotate around a third axis;

[0071] A third transmission structure 15, a part of the third transmission structure 15 is located inside the spherical space 12, and another part is located outside the rotating spherical shell 2, and the third driving motor 8 drives the output disk 4 to rotate around the third axis through the third transmission structure 15.

[0072] In this embodiment, the base 1 serves as the fixed end and includes a fixed spherical shell 101 and a base fixed to the lower end of the fixed spherical shell 101, and the base can be fixed on the exercise equipment. The fixed spherical shell 101 can be a hemispherical shell structure or a spherical shell structure with any proportion. The motor frame 5 is fixedly installed in the fixed spherical shell 101, and the lower end of the motor frame 5 is fixedly connected to the fixed spherical shell 101. To reasonably allocate space, the motor frame 5 can be fixed at the middle position of the fixed spherical shell 101, so that a uniform space is formed between the periphery of the motor frame 5 and the fixed spherical shell 101. The motor frame 5 serves as a structure for installing the drive motor, and three installation positions for installing the drive motor can be formed on the motor frame 5. The installation positions can be installation grooves, installation holes, etc. provided on the motor frame 5. Installing the drive motor through structures such as installation grooves or installation holes can reasonably utilize the internal space and reduce the space occupied by the drive motor.

[0073] In this embodiment, three drive motors are provided, namely a first drive motor 6, a second drive motor 7, and a third drive motor 8. The three drive motors can individually output rotational motion, and after being connected to the corresponding output members through the corresponding transmission structures, they can respectively achieve the motion output of three degrees of freedom. Of course, in some cases, the three drive motors can also be linked to achieve a more complex motion output. As Figure 2 shown, the three drive motors can be arranged circumferentially on the motor frame 5, and the output axes of the three drive motors are parallel.

[0074] The moving parts in this embodiment include a rotating ball shell 2, an output ball shell 3, and an output disk 4. Among them, the rotating ball shell 2 is a hemispherical shell structure or a spherical shell structure with any proportion. As Figure 3 shown, the rotating ball shell 2 and the fixed spherical shell 101 are arranged opposite to each other, thus enclosing a spherical space 12. The motor frame 5 is located in this spherical space 12, and the first drive motor 6, the second drive motor 7, and the third drive motor 8 are also located in this spherical space 12. The rotating ball shell 2 can rotate around a fixed axis relative to the fixed spherical shell 101, and its rotation axis is the first axis. In one implementation manner, the inner side of the rotating ball shell 2 can be rotationally connected to the motor frame 5 through a bearing, and the axis of this bearing is the first axis. The lower end surface of the rotating ball shell 2 corresponds to and is close to the upper end surface of the fixed spherical shell 101 up and down. In another implementation manner, the lower end surface of the rotating ball shell 2 is rotationally connected to the upper end surface of the fixed spherical shell 101 through a planar bearing, and the rotating ball shell 2 realizes rotation around a fixed axis through the corresponding shaft or retaining ring, and the axis of the planar bearing is the first axis.

[0075] As Figure 3As shown in the figure, the output spherical shell 3 is mounted on the rotating spherical shell 2 and can rotate about a fixed axis relative to the rotating spherical shell 2. The rotation axis of the output spherical shell 3 is the second axis. To achieve the output of multi-degree-of-freedom motion, after the rotating spherical shell can output the rotational motion about the first axis, the output spherical shell 3 needs to output the rotational motion about another axis. Therefore, the second axis and the first axis are not collinear, and there is a certain angle between them. In one embodiment, the output spherical shell 3 can be connected by a rotating shaft provided on the rotating spherical shell 2, or a rotating shaft can be provided on the output spherical shell 3 to connect the rotating spherical shell 2 through the rotating shaft.

[0076] As Figure 3 shown in the figure, the output disk 4 is mounted on the output spherical shell 3 and can rotate about a fixed axis relative to the output spherical shell 3. The rotation axis of the output disk 4 is the third axis. The output disk 4 and the output spherical shell 3 can be connected by a corresponding shaft, and the axis of this shaft is used as the third axis. The third axis and the second axis are not collinear. The output disk 4 is the end motion structure of the spherical joint, and the motions of the rotating spherical shell and the output spherical shell 3 can also act on the output disk 4. Therefore, the output disk 4 can be connected to the end of the motion device, such as connected to the movable robotic arm of a robot, or connected to the end effector of the robotic arm, etc.

[0077] To drive the rotation of the rotating spherical shell 2, the output spherical shell 3 and the output disk 4, a corresponding transmission structure needs to be configured in this embodiment. Specifically, the transmission structure includes a first transmission structure 13, a second transmission structure 14, and a third transmission structure 15. Among them, the first transmission structure 13 is used to transmit the rotational force of the first drive motor 6 to the rotating spherical shell 2 to drive the rotating spherical shell 2 to rotate about the first axis. The second transmission structure 14 is used to transmit the rotational force of the second drive motor 7 to the output spherical shell 3 to drive the output spherical shell 3 to rotate about the second axis. Both the first transmission structure 13 and the second transmission structure 14 can be completely arranged within the spherical space 12. The third transmission structure 15 is used to transmit the rotational force of the third drive motor 8 to the output disk 4. Since the output disk 4 is mounted on the output spherical shell 3 and the third drive motor 8 is mounted within the spherical space 12, a part of the third transmission structure 15 needs to be located between the rotating spherical shell 2 and the output spherical shell 3, and a part needs to be located within the spherical space 12. The part located between the rotating spherical shell 2 and the output spherical shell 3 can be covered by the output spherical shell 3 to avoid exposure.

[0078] The first transmission structure 13, the second transmission structure 14, and the third transmission structure 15 have various arrangement methods, as long as the transmission of rotational power can be achieved. In one embodiment, the first transmission structure 13, the second transmission structure 14, and the third transmission structure 15 are all gear transmission structures. The gear transmission structure has the advantages of high transmission accuracy and easy control.

[0079] In the present invention, by using the rotating ball shell 2, the output ball shell 3, and the output disc 4 as components for outputting one-degree-of-freedom motion respectively, a spherical space 12 is formed by the fixed ball shell 101 and the rotating ball shell 2. The first driving motor 6, the second driving motor 7, and the third driving motor 8 responsible for driving are all arranged within this spherical space 12, and a part of the first transmission structure 13, the second transmission structure 14, and the third transmission structure 15 responsible for transmission is arranged within the spherical space 12. This achieves the purpose of fully utilizing the spherical space 12 formed by the fixed ball shell 101 and the rotating ball shell 2 to arrange the driving motors and the transmission structure, thereby realizing the reduction of the overall volume and occupied space of the spherical joint, increasing the flexibility of the joint, and having a relatively flat surface of the spherical joint after the driving motors and the transmission structure are arranged inside, which is beneficial to the installation and use of the spherical joint in motion equipment. Furthermore, it solves the problems in the related art that the overall volume of the multi-degree-of-freedom motion joint is relatively large, occupying a large amount of space, and having poor flexibility in use.

[0080] On the other hand, in the present invention, the rotating ball shell 2 and the output ball shell 3 are components for outputting two-degree-of-freedom motion respectively, and the output ball shell 3 can rotate about a fixed axis on the rotating ball shell 2. When the inner arc surface of the output ball shell 3 and the outer arc surface of the rotating ball shell 2 are concentric arc surfaces, a relatively small spacing is designed between the output ball shell 3 and the rotating ball shell 2, which can satisfy the free rotation of the output ball shell 3, thereby further reducing the volume of the entire spherical joint.

[0081] In an embodiment of the first transmission structure 13, as Figure 4 shown, the first transmission structure 13 includes a ball shell gear ring 131 and a first gear 130. The ball shell gear ring 131 is fixedly arranged on the inner side of the rotating ball shell 2, and the first gear 130 is fixedly arranged on the output shaft of the first driving motor 6. The first gear 130 meshes with the ball shell gear ring 131.

[0082] Specifically, in this embodiment, the ball shell gear ring 131 is fixed on the inner side of the rotating ball shell 2 and is located at the lower part of the rotating ball shell 2. The ball shell gear ring 131 and the rotating ball shell 2 can be of an integrally formed structure. The first gear 130 is sleeved and fixed on the output shaft of the first driving motor 6. By driving the first gear 130 to rotate about a fixed axis by the first driving motor 6, the ball shell gear ring 131 meshing with it is driven to rotate about the first axis, and then the rotating ball shell 2 is driven to rotate about the first axis to complete the operation 2 as Figure 7 shown. It can be understood that since both the output ball shell 3 and the output disc 4 are arranged on the rotating ball shell 2, during the rotation of the rotating ball shell 2, the output ball shell 3 and the output disc 4 rotate synchronously.

[0083] In an embodiment, as Figure 3 shown, a first bearing 10 is sleeved and fixed on the motor bracket 5, and the lower end of the rotating ball shell 2 is sleeved and fixed on the outer ring of the first bearing 10.

[0084] Specifically, in this embodiment, a first bearing 10 is sleeved and fixed on the upper part of the motor frame 5, and the lower part of the rotating ball shell 2 is sleeved and fixed on the outer ring of the first bearing 10, so that the rotating ball shell 2 can rotate relative to the fixed ball shell 101.

[0085] While serving as a moving part, the rotating ball shell 2 also serves as the mounting base for two other moving parts. Therefore, the rotating ball shell 2 needs to have high structural stability to improve the motion accuracy of the spherical joint. For this purpose, in this embodiment, as Figure 3 shown, a first shaft body 9 is fixed on the motor frame 5. The axis of the first shaft body 9 is the first axis. A second bearing 11 is sleeved and fixed on the upper end of the first shaft body 9, and the upper end of the rotating ball shell 2 is sleeved and fixed on the outer ring of the second bearing 11.

[0086] Specifically, in this embodiment, the first shaft body 9 is located in the middle of the motor frame 5 and extends upward. The upper end of the rotating ball shell 2 is rotatably connected to the upper end of the first shaft body 9 through the second bearing 11, and the lower end of the rotating ball shell 2 is rotatably connected to the motor frame 5 through the first bearing 10, so that the rotating ball shell 2 has high rotational stability. Grooves or holes can be formed in the upper end of the rotating ball shell 2 for the installation of the first shaft body 9 and the second bearing 11.

[0087] As Figure 4 shown, in an embodiment of the second transmission structure 14, the second transmission structure 14 includes a second gear 140, a third gear 141 and a fourth gear 142;

[0088] A second shaft body 16 is arranged inside the output ball shell 3. The axis of the second shaft body 16 is the second axis. The end of the second shaft body 16 passes through the rotating ball shell 2 and extends into the spherical space 12, and the second shaft body 16 is rotatably connected to the rotating ball shell 2;

[0089] The second gear 140 is fixed on the output shaft of the second driving motor 7. The third gear 141 is rotatably arranged on the first shaft body 9 and meshes with the second gear 140. The fourth gear 142 is fixed on the second shaft body 16 and meshes with the third gear 141.

[0090] Specifically, in this embodiment, a shaft hole is provided on the rotating ball shell 2. The second shaft body 16 passes through the shaft hole and is rotatably connected to the shaft hole. A fourth gear 142 is fixedly provided on the part of the second shaft body 16 extending into the spherical space 12. By driving the fourth gear 142 to rotate, the second shaft body 16 is driven to rotate in the shaft hole, and then the output ball shell 3 is driven to rotate. To drive the fourth gear 142, in this embodiment, a second gear 140 is fixed to the output shaft of the second driving motor 7. Due to space limitations, to transmit the power of the second gear 140 to the fourth gear 142, in this embodiment, a third gear 141 is provided on the first shaft body 9. The third gear 141 can be connected to the first shaft body 9 through a bearing, so that the third gear 141 can rotate on the first shaft body 9. At the same time, both ends of the third gear 141 are meshed with the second gear 140 and the fourth gear 142 respectively. By driving the second gear 140 to rotate by the second driving motor 7, the third gear 141 is driven to rotate on the first shaft body 9, and then the fourth gear 142 and the second shaft body 16 are driven to rotate, and finally the output ball shell 3 is driven to rotate around the second axis to complete the operation as Figure 7 shown in

[0091] as Figure 5 shown. Since there is a certain angle between the second shaft body 16 and the first shaft body 9, and the first shaft body 9 is parallel to the output shaft of the second driving motor 7, and at the same time, the third gear 141 installed on the first shaft body 9 needs to transmit power to the fourth gear 142 sleeved on the second shaft body 16. Therefore, in this embodiment, the third gear 141 includes a straight tooth section 1410 and a bevel tooth section 1411. The fourth gear 142 is set as a bevel gear. The straight tooth section 1410 is meshed with the second gear 140, and the bevel tooth section 1411 is meshed with the fourth gear 142.

[0092] Specifically, in this embodiment, the fourth gear 142 is a bevel gear. The third gear 141 can be formed by combining a straight gear and a bevel gear. The straight gear can be key-connected or welded and fixed to the lower end of the bevel gear. The straight gear serves as the straight tooth section 1410 and is meshed with the second gear 140, and the bevel gear serves as the bevel tooth section 1411 and is meshed with the fourth gear 142, so as to achieve power transmission when there is an angle in the power transmission direction.

[0093] In one embodiment, the second shaft body 16 forms a 45° angle with the first shaft body 9. Of course, the two can also form other angles, and the present invention does not limit this here.

[0094] In one embodiment, as Figure 5 shown, a third shaft body 17 is provided on the outer side of the output ball shell 3. The axis of the third shaft body 17 is the third axis. The output disc 4 is rotatably arranged on the third shaft body 17;

[0095] The third transmission structure 15 includes a fifth gear 150, a sixth gear 151, a seventh gear 152, and an eighth gear 153. The fifth gear 150 is fixed to the output shaft of the third drive motor 8. The sixth gear 151 is rotatably disposed on the first shaft body 9 and meshes with the fifth gear 150. The seventh gear 152 is rotatably disposed on the second shaft body 16 and meshes with the sixth gear 151.

[0096] The eighth gear 153 is fixed to the inner side of the output disk 4 and meshes with the seventh gear 152.

[0097] Specifically, in this embodiment, the output spherical shell 3 and the output disk 4 are connected by a third shaft body 17. The third shaft body 17 can be a shaft-like structure fixed to the top of the output spherical shell 3. The output disk 4 can be rotatably mounted on the third shaft body 17 through a bearing. There is a space between the output spherical shell 3 and the rotating spherical shell 2 to install a part of the third transmission structure 15 located outside the rotating spherical shell 2. Specifically, in this embodiment, this space is used to install the eighth gear 153 in the third transmission structure 15 and at least a part of the seventh gear 152. In the third transmission structure 15, the fifth gear 150 is fixed to the output shaft of the third drive motor 8, the sixth gear 151 is rotatably connected to the first shaft body 9 through a bearing, and the seventh gear 152 is rotatably connected to the second shaft body 16 through a bearing. The third drive motor 8 drives the fifth gear 150 to rotate, thereby driving the sixth gear 151 to rotate, and then the seventh gear 152 to rotate, and then driving the eighth gear 153 to rotate, and finally driving the output disk 4 fixedly connected to the eighth gear 153 to rotate to complete the action 3 as Figure 7 shown.

[0098] Since the sixth gear 151 is installed on the first shaft body 9 and the seventh gear 152 is installed on the second shaft body 16, the axes of the sixth gear 151 and the seventh gear 152 also have a certain included angle. And since the output shaft of the third drive motor 8 is parallel to the first shaft body 9, in order for the third drive motor 8 to drive the seventh gear 152 to rotate, the sixth gear 151 and the seventh gear 152 also need to mesh through the bevel gear section 1411. Therefore, in this embodiment, the sixth gear 151 includes a transmission lower tooth 1510 and a transmission upper tooth 1511. The transmission lower tooth 1510 meshes with the fifth gear 150, and the transmission upper tooth 1511 and the seventh gear 152 are bevel gears and mesh with each other.

[0099] Specifically, in this embodiment, the transmission lower tooth 1510 can be a spur gear, the transmission upper tooth 1511 is a bevel gear, and the seventh gear 152 includes a bevel gear that can mesh with the transmission upper tooth 1511. In one implementation, the transmission upper tooth 1511 and the transmission lower tooth 1510 are two gears. The lower end of the transmission upper tooth 1511 and the upper end of the transmission lower tooth 1510 can be key-connected or welded and fixed, and can be rotatably connected to the first shaft body 9 through a bearing respectively.

[0100] Similarly, since the seventh gear 152 needs to mesh with the eighth gear 153 while maintaining the meshing relationship with the driving upper tooth 1511, in this embodiment, the seventh gear 152 includes a driving inner tooth 1520 and a driving outer tooth 1521. The driving inner tooth 1520 meshes with the driving upper tooth 1511, and the driving outer tooth 1521 is located outside the rotating ball housing 2 and meshes with the eighth gear 153.

[0101] Specifically, in this embodiment, the driving inner tooth 1520 and the driving outer tooth 1521 can be two gears. The outer end of the driving inner tooth 1520 and the inner end of the driving outer tooth 1521 can be fixedly connected by a key or welded and are respectively rotatably connected to the second shaft body 16 through a bearing. The tooth part of the driving inner tooth 1520 is located within the spherical space 12 and meshes with the driving upper tooth 1511, and the tooth part of the driving outer tooth 1521 is located outside the rotating ball housing 2 and meshes with the eighth gear 153.

[0102] In one implementation, the fourth gear 142 is fixedly provided at the end of the second shaft body 16. The driving inner tooth 1520 can be mounted on the fourth gear 142 through a bearing, and the driving outer tooth 1521 is mounted on the second shaft body 16 through a bearing, thereby reasonably separating and combining the axial space of the fourth gear 142, reducing the length requirement for the second shaft body 16, and further reducing the volume and space occupation.

[0103] Since in the present invention, the third gear 141 is mounted on the first shaft body 9 through a bearing, and the driving inner tooth 1520 and the driving outer tooth 1521 are also mounted on the first shaft body 9 through a bearing, in order to reasonably utilize the axial space of the first shaft body 9 and reasonably perform power transmission, the third gear 141 is rotatably sleeved outside the sixth gear 151 and is located between the driving lower tooth 1510 and the driving upper tooth 1511.

[0104] Specifically, in this embodiment, the height of the second gear 140 is higher than that of the fifth gear 150, so that the meshing of the second gear 140 and the third gear 141 will not interfere with the meshing of the fifth gear 150 and the sixth gear 151. The fourth gear 142 is closer to the center of the spherical space 12 relative to the driving inner tooth 1520, so that the meshing of the fourth gear 142 and the third gear 141 will not interfere with the meshing of the driving upper tooth 1511 and the driving inner tooth 1520. By this layout method, the spherical space 12 is fully utilized, the volume and space occupation of the transmission structure are reduced, and the volume of the spherical space 12 is further reduced.

[0105] Since the output spherical shell 3 needs to rotate about the axis of the second shaft body 16 on the rotating table spherical shell 2, and the output disk 4 is installed on the output spherical shell 3, during the rotation of the output spherical shell 3, the output disk 4 and the eighth gear 153 fixedly connected to the output disk 4 also need to rotate relative to the rotating table spherical shell 2. At the same time, since at least a part of the eighth gear 153 needs to be located between the rotating table spherical shell 2 and the output spherical shell 3, in order to enable the eighth gear 153 to rotate smoothly relative to the rotating table spherical shell 2 and reduce the space occupation, as Figure 6 shown, in this embodiment, the eighth gear 153 includes an arc-shaped disk 1530. The inner arc surface of the arc-shaped disk 1530 and the outer arc surface of the rotating table spherical shell 2 are concentric arc surfaces. Teeth are provided on the edge of the arc-shaped disk 1530, and a connecting protrusion 1531 is provided in the middle of the arc-shaped disk 1530. The connecting protrusion 1531 is fixedly connected to the output disk 4 and is rotatably connected to the third shaft body 17.

[0106] Specifically, in this embodiment, a hole is provided at the top of the output spherical shell 3. The third shaft body 17 is fixed at the top of the output spherical shell 3 and the third shaft body 17 has a through shaft hole, and the shaft hole corresponds to the hole at the top of the output spherical shell 3. The arc-shaped disk 1530 of the eighth gear 153 is located between the rotating table spherical shell 2 and the output spherical shell 3. The connecting protrusion 1531 is located at the top of the arc-shaped disk 1530 and is fixedly connected to the output disk 4 after passing through the shaft hole of the third shaft body 17. The outside of the connecting protrusion 1531 is rotatably connected to the third shaft body 17 through a bearing.

[0107] On the basis of the above embodiment, to solve the related technical problems, a spherical joint motion control method is used to control the motion of a spherical joint. The spherical joint is the spherical joint in the above embodiment, and it includes: a fixed spherical shell 101, a rotating table spherical shell 2, an output spherical shell 3 and an output disk 4. The rotating table spherical shell 2 is arranged on the fixed spherical shell 101 and can rotate about the first axis. The output spherical shell 3 is arranged on the rotating table spherical shell 2 and can rotate about the second axis. The output disk 5 is arranged on the output spherical shell 3 and can rotate about the third axis;

[0108] As Figure 8 shown, the motion control method includes:

[0109] S10. Obtain the pose of the output disk 4 in the base coordinate system. The pose includes the coordinates and rotation angle of the output disk 4. The base coordinate system is a coordinate system established with the first axis as the coordinate axis and the intersection position of the second axis and the first axis as the origin.

[0110] Specifically, the Cartesian pose (x, y, z, yaw) of the key points on the output disk 4 in the base coordinate system can be obtained through a sensor or a positioning and tracking module. Among them, the coordinates of the key points on the output disk 4 in the base coordinate system are (x, y, z), and the rotation angle j3 = yaw. The base coordinate system is a coordinate system established with the first axis as the coordinate axis and the intersection position of the second axis and the first axis as the origin o. For the convenience of calculation, the key point of the output disk 4 can be the rotation center of the output disk 4.

[0111] S20. Solve the rotation angles of the output spherical shell 3 and the rotating spherical shell 2 according to the geometric structure of the spherical joint and the coordinates of the output disk 4.

[0112] Specifically, the geometric structure of the spherical joint can be geometrically analyzed, and the rotation angles of the output spherical shell 3 and the rotating spherical shell 2 can be calculated according to the corresponding geometric relationships, which are denoted as j1 and j2 respectively.

[0113] S30. Adopt inverse kinematics to solve the rotation angles of the corresponding motors according to the rotation angle of the output disk 4, the rotation angle of the output spherical shell 3, and the rotation angle of the rotating spherical shell 2.

[0114] Specifically, since the output spherical shell 3 is installed on the rotating spherical shell 2 and the output disk 4 is installed on the output spherical shell 3, when the rotating spherical shell 2 rotates around the first axis, it will also drive the output spherical shell 3 to rotate around the first axis, and when the output spherical shell 3 rotates around the second axis, it will also drive the output disk 4 to rotate around the second axis. Therefore, inverse kinematics needs to be adopted to solve the rotation angles of the corresponding motors according to the rotation angle of the output disk, the rotation angle of the output spherical shell, and the rotation angle of the rotating spherical shell, and calculations need to be performed according to the corresponding transmission ratio and reduction ratio during this process.

[0115] The present invention realizes the technical effects of simplifying the motion control process of the spherical joint and improving the solving efficiency of the rotation angles of each motor, and further solves the problems that the motion control of the spherical joint in the related art is relatively complex and the solving efficiency is not high.

[0116] In an embodiment, the first axis is located on the z-axis of the base coordinate system, the included angle between the second axis and the xoy plane in the base coordinate system is θ, 0° ≤ θ ≤ 90°, and the rotation angle j2 of the output spherical shell 3 is calculated by the following formula:

[0117]

[0118] The rotation angle j1 of the rotating spherical shell 2 is calculated by the following formula:

[0119]

[0120] Wherein, R is the radius of the rotating billiard shell 2, the coordinates of the key point on the output disk 4 in the base coordinate system are (x, y, z), the base coordinate system is a coordinate system established with the first axis as the coordinate axis and the intersection position of the second axis and the first axis as the origin, L1 is the length of OA, L2 is the length of AB, point B is the key point on the output disk 4, point O is the origin of the base coordinate system, and point A is the foot of the perpendicular from point B on the second axis.

[0121] In one embodiment, for further facilitating control, the angle θ between the second axis and the xoy plane in the base coordinate system is 45°.

[0122] In one embodiment, the rotating billiard shell 2, the output spherical shell 3 and the output disk 4 are all driven to rotate by a motor gear transmission structure;

[0123] Combined with the structure of the spherical joint in the above embodiment, using inverse kinematics, according to the rotation angle of the output disk, the rotation angle of the output spherical shell and the rotation angle of the rotating billiard shell, solving the rotation angle of the corresponding motor includes:

[0124] According to the reduction ratio of the rotating billiard shell to the corresponding motor and the rotation angle of the rotating billiard shell, calculating the rotation angle of the motor corresponding to the rotating billiard shell;

[0125] According to the rotation angle of the rotating billiard shell, the reduction ratio of the output spherical shell to the corresponding motor, the rotation angle of the output spherical shell and the end gear ratio of the output spherical shell, calculating the rotation angle of the motor corresponding to the output spherical shell;

[0126] According to the rotation angle of the rotating billiard shell, the rotation angle of the output spherical shell, the reduction ratio of the output disk to the corresponding motor, the end gear ratio of the output disk, the two-stage gear ratio of the end of the output disk, and the rotation angle of the output disk, calculating the rotation angle of the motor corresponding to the output disk.

[0127] Specifically, the first drive motor is used to drive the rotation of the rotating billiard shell 2, the second drive motor is used to drive the rotation of the output spherical shell 3, and the third drive motor is used to drive the rotation of the output disk 4. In a certain motion state, the rotation angle of the first drive motor is m1, the rotation angle of the second drive motor is m2, and the rotation angle of the third drive motor is m3.

[0128] Furthermore, the rotation angle m1 of the motor corresponding to the rotating billiard shell is calculated by the following formula:

[0129]

[0130] The rotation angle m2 of the motor corresponding to the output spherical shell is calculated by the following formula:

[0131]

[0132] The rotation angle m3 of the motor corresponding to the output disk is calculated using the following formula:

[0133]

[0134] j 1_reduction_ratio : Reduction ratio of the rotating billiard ball shell to the first drive motor;

[0135] j 2_reduction_ratio : Reduction ratio of the output ball shell to the second drive motor:

[0136] j 3_reduction_ratio : Reduction ratio of the output disk to the third drive motor:

[0137] j 2_gear_ratio : Output ball shell end gear ratio:

[0138] j 3_gear_ratio : Output disk end gear ratio:

[0139] h 3_two_stage_gear_ratio : Output disk end two-stage gear reduction ratio.

[0140] According to another aspect of the present invention, a motion system is provided, including a spherical joint and a control module, and the control module is used to execute the above control method.

[0141] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A spherical joint motion control method, characterized in that, For controlling the movement of a spherical joint, the spherical joint includes: a fixed spherical shell, a rotating spherical shell, an output spherical shell, and an output disk. The rotating spherical shell is arranged on the fixed spherical shell and can rotate around a first axis. The output spherical shell is arranged on the rotating spherical shell and can rotate around a second axis. The output disk is arranged on the output spherical shell and can rotate around a third axis; The motion control method includes: Obtaining the pose of the output disk in the base coordinate system, where the pose includes the coordinates and rotation angle of the output disk. The base coordinate system is a coordinate system established with the first axis as the coordinate axis and the intersection position of the second axis and the first axis as the origin; Solving the rotation angles of the output spherical shell and the rotating spherical shell according to the geometric structure of the spherical joint and the coordinates of the output disk; Using inverse kinematics to solve the rotation angles of the corresponding motors according to the rotation angle of the output disk, the rotation angle of the output spherical shell, and the rotation angle of the rotating spherical shell.

2. The spherical joint motion control method according to claim 1, wherein The first axis is located on the z-axis of the base coordinate system. The angle between the second axis and the xoy plane in the base coordinate system is θ, where 0° ≤ θ ≤ 90°. The rotation angle j2 of the output spherical shell is calculated using the following formula: The rotation angle j1 of the rotating spherical shell is calculated using the following formula: Where R is the radius of the rotating spherical shell. The coordinates of a key point on the output disk in the base coordinate system are (x, y, z). The base coordinate system is a coordinate system established with the first axis as the coordinate axis and the intersection position of the second axis and the first axis as the origin. L1 is the length of OA, L2 is the length of AB, point B is the key point on the output disk, point O is the origin of the base coordinate system, and point A is the foot of the perpendicular from point B to the second axis.

3. The spherical joint motion control method according to claim 2, wherein, The angle θ between the second axis and the xoy plane in the base coordinate system is 45°.

4. The spherical joint motion control method according to claim 3, characterized in that The key point is the rotation center of the output disk.

5. The spherical joint motion control method according to claim 4, characterized in that, Using inverse kinematics to solve the rotation angles of the corresponding motors according to the rotation angle of the output disk, the rotation angle of the output spherical shell, and the rotation angle of the rotating spherical shell includes: Calculating the rotation angle of the motor corresponding to the rotating spherical shell according to the reduction ratio from the rotating spherical shell to the corresponding motor and the rotation angle of the rotating spherical shell; Calculating the rotation angle of the motor corresponding to the output spherical shell according to the rotation angle of the rotating spherical shell, the reduction ratio from the output spherical shell to the corresponding motor, the rotation angle of the output spherical shell, and the end gear ratio of the output spherical shell; Calculating the rotation angle of the motor corresponding to the output disk according to the rotation angle of the rotating spherical shell, the rotation angle of the output spherical shell, the reduction ratio from the output disk to the corresponding motor, the end gear ratio of the output disk, the two-stage end gear ratio of the output disk, and the rotation angle of the output disk.

6. The spherical joint motion control method according to claim 5, wherein, The rotation angle m1 of the motor corresponding to the rotating spherical shell is calculated using the following formula: The rotation angle m2 of the motor corresponding to the output spherical shell is calculated using the following formula: The rotation angle m3 of the motor corresponding to the output disk is calculated using the following formula: j 1_reduction_ratio : Reduction ratio of the rotating billiard ball shell to the corresponding motor; j 2_reduction_ratio : Reduction ratio of the output spherical shell to the corresponding motor: j 3_reduction_ratio : Reduction ratio from the output disk to the corresponding motor: j 2_gear_ratio : Output spherical shell end gear ratio: j 3_gear_ratio : Output disk end gear ratio: j 3_two_stage_gear_ratio : Reduction ratio of two-stage gears at the end of the output disk.

7. A spherical joint, characterized in that, Controlled using the control method according to any one of claims 1 to 6, the spherical joint includes: A base, and the base includes a fixed spherical shell; The motor bracket is disposed within the fixed spherical shell, and a first driving motor, a second driving motor, and a third driving motor are provided on the motor bracket; The rotating ball shell is opposite to the fixed spherical shell and encloses a spherical space, and the rotating ball shell can rotate about a first axis; The first transmission structure is disposed within the spherical space, and the first driving motor drives the rotating ball shell to rotate about the first axis through the first transmission structure; The output ball shell is disposed on the rotating ball shell and can rotate about a second axis; The second transmission structure is disposed within the spherical space, and the second driving motor drives the output ball shell to rotate about the second axis through the second transmission structure; The output disk is disposed on the output ball shell and can rotate about a third axis; The third transmission structure, a part of which is located within the spherical space and another part is located outside the rotating ball shell, and the third driving motor drives the output disk to rotate about the third axis through the third transmission structure.

8. The spherical joint according to claim 7, characterized in that, The first transmission structure, the second transmission structure, and the third transmission structure are all gear transmission structures.

9. The spherical joint according to claim 7, characterized in that, The first driving motor, the second driving motor, and the third driving motor are arranged circumferentially.

10. A motion system, characterized in that, It includes a spherical joint and a control module, and the control module is used to execute the control method according to any one of claims 1 to 6.

Images