A three-degree-of-freedom rope-driven direct-drive series wrist based on gear constraint

Abstract

The application discloses a three-degree-of-freedom rope driving direct-drive series wrist based on gear constraint, which comprises a first arm section, a second arm section, a third arm section, a gripper, a first rope driving mechanism, a second rope driving mechanism and a third rope driving mechanism; the first arm section and the first end of the second arm section are connected through a gear joint rotating structure, the second end of the second arm section and the first end of the third arm section are connected through a gear joint rotating structure, and the second end of the third arm section is rotatably connected with the gripper; the rotating axial directions of the first end of the second arm section, the first end of the third arm section and the gripper are perpendicular to each other; the first rope driving mechanism, the second rope driving mechanism and the third rope driving mechanism are used for independently controlling the rotation of the second arm section, the third arm section and the gripper; the application not only greatly reduces the difficulty of parts and installation, but also reduces the difficulty of forward and inverse kinematics modeling, and practically solves the difficulties existing in the prior art.

Description

Technical Field

[0001] This invention relates to the technical field of robotic arms, and in particular to a three-degree-of-freedom rope-driven direct-drive serial wrist based on gear constraints. Background Technology

[0002] In recent years, a type of robotic arm with rope-driven pure rolling joints has become a research hotspot in both academia and industry. Compared to traditional industrial robotic arms, the joint motors of this type of robotic arm are located near the base, and power is transmitted to the joints via ropes, thereby reducing the arm's mass and improving its agility. A significant feature that distinguishes this type of robotic arm from traditional industrial robotic arms is that it has rope-driven circular pure rolling joints or / and rope-driven spherical pure rolling joints.

[0003] The relevant existing technologies are as follows:

[0004] Existing technology 1, Y.-J. Kim, J.-I. Kim and W. Jang, “Quaternion Joint: Dexterous 3-DOF Joint Representing Quaternion Motion for High-Speed ​​Safe Interaction,” 2018 IEEE / RSJ International Conference on Intelligent Robots and Systems (IROS), Madrid, Spain, 2018, pp. 935-942. This paper proposes a novel, dexterous, three-degree-of-freedom (3-DOF) virtual spherical wrist mechanism for LIMS2, called a quaternion joint, which has a large range of motion and uniform maneuverability without singularities throughout the entire range of motion. This joint consists of a 2-DOF spherical pure rolling joint and two pairs of drive cables, and can be regarded as a parallel joint. Based on this characteristic, it has simple and clear forward and inverse kinematics and high maneuverability. By adding a 1-DOF rotary joint at the distal end of the quaternion joint, it can be extended into a 3-DOF joint mechanism.

[0005] The quaternion virtual ball joint design offers many significant advantages, such as a large range of motion, high maneuverability, lightweight construction, and a simple and reliable structure. However, this joint also has some drawbacks, as detailed below:

[0006] 1. The design of the quaternion virtual spherical wrist joint is complex, with a large number of parts, making installation difficult, and the complexity brought about by the rope installation is also very high.

[0007] 2. The forward kinematics of the quaternion virtual spherical wrist joint is more complex than that of the traditional serial joint.

[0008] 3. Quaternion virtual spherical wrist joints have low stiffness, which may lead to significant accuracy problems under high loads.

[0009] 4. The above-mentioned joints are purely mechanical joints with no feedback mechanism. Their accuracy depends entirely on the tension of the rope and the friction between the rope pulleys.

[0010] Existing technology two, the UR5 robotic arm, is a lightweight collaborative industrial robotic arm developed by Universal Robots of Denmark. It is renowned for its ease of use, flexibility, and safety. The UR5 robotic arm is designed with user experience in mind; its setup and deployment process is quick and flexible, allowing for easy integration into existing production lines to help improve productivity and quality. Furthermore, the UR5e is an upgraded version of the UR5, offering more features and improved performance, including higher repeatability and wider application adaptability.

[0011] The wrist joint of this robotic arm has three degrees of freedom, and these three degrees of freedom are offset, so it can be regarded as three joints connected in series. The advantage of this design is that the forward and inverse kinematics of the wrist joint are relatively simple, and it can be directly modeled using the DH method. It also adopts a modular design concept, which facilitates maintenance and replacement. However, the UR5 wrist joint still has the following disadvantages:

[0012] 1. The mass is relatively large. Because the motor is directly installed on the rotary joint, the mass of the wrist joint is relatively large, resulting in a large ratio of its own weight to load. The UR5 robotic arm weighs 18.4kg, and its maximum load is only 5kg.

[0013] 2. Due to the large mass of the wrist, the wrist joint operates at a low speed, which may make it difficult in some special scenarios.

[0014] 3. The wrist has high rigidity, which leads to poor safety during operation.

[0015] Therefore, how to solve the above-mentioned problems in the existing technology has become a difficult problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0016] The purpose of this invention is to provide a three-degree-of-freedom rope-driven direct-drive serial wrist based on gear constraints, so as to solve the problems of complex structure and difficult design of existing structures.

[0017] To address the aforementioned technical problems, this invention provides a three-degree-of-freedom rope-driven direct-drive serial wrist based on gear constraints, comprising a first arm segment, a second arm segment, a third arm segment, a gripper, a first rope drive mechanism, a second rope drive mechanism, and a third rope drive mechanism; the first arm segment and the first end of the second arm segment form a gear joint rotation structure, the second end of the second arm segment and the first end of the third arm segment also form a gear joint rotation structure, the second end of the third arm segment is rotatably connected to the gripper, and the rotational axes of the first end of the second arm segment, the first end of the third arm segment, and the gripper are all mutually perpendicular; the first rope drive mechanism, the second rope drive mechanism, and the third rope drive mechanism are respectively used to independently control the rotation of the second arm segment, the third arm segment, and the gripper.

[0018] In one embodiment, the first arm segment is provided with two separate, oppositely arranged first gear plates, and the first end of the second arm segment is provided with two separate, oppositely arranged second front gear plates. The two first gear plates mesh with the two second front gear plates respectively. The three-degree-of-freedom rope-driven direct-drive serial wrist also includes a first connecting plate. The two first connecting plates are respectively located on the outer sides of the first arm segment and the second arm segment. A first rotating shaft and a second front rotating shaft are rotatably connected between the two sides of the two first connecting plates. The first rotating shaft passes through the two first gear plates to form a fixed connection, and the second front rotating shaft passes through the two second front gear plates to form a fixed connection.

[0019] In one embodiment, the first rope drive mechanism includes a first force-bearing winding wheel and a first drive rope. The two first force-bearing winding wheels are connected and fixed to the second front rotating shaft. The two first drive ropes pass around the two first force-bearing winding wheels in opposite winding directions, and the two first drive ropes are respectively connected and fixed to the two first force-bearing winding wheels. The pulling of the two first drive ropes is used to drive the second arm segment to rotate in different directions.

[0020] In one embodiment, the first arm segment is provided with a positioning shaft, the axial direction of which is the same as the axial direction of the first rotating shaft; the first rope drive mechanism further includes a first-numbered rope winding wheel and a second-numbered rope winding wheel, the two first-numbered rope winding wheels are disposed on the positioning shaft, the two first-numbered rope winding wheels are disposed on the first rotating shaft, and the first drive rope passes around the first-numbered rope winding wheel, the first-numbered rope winding wheel and the first force-bearing rope winding wheel in an alternating winding direction.

[0021] In one embodiment, the second end of the second arm segment is provided with two separate and oppositely arranged second rear gear plates, and the first end of the third arm segment is provided with two separate and oppositely arranged third gear plates. The two second rear gear plates mesh with the two third gear plates respectively. The three-degree-of-freedom rope-driven direct-drive serial wrist also includes a second connecting plate. The two sides of the second connecting plate are respectively located between the two second rear gear plates and between the two third gear plates. The two sides of the second connecting plate are respectively provided with a second rear rotating shaft and a third rotating shaft. The second rear rotating shaft passes through the two second rear gear plates to form a fixed connection, and the third rotating shaft passes through the two third gear plates to form a rotatable connection.

[0022] In one embodiment, the second rope drive mechanism includes a second force-bearing winding wheel and a second drive rope. The two second force-bearing winding wheels are respectively connected and fixed to the outside of the two third gear plates. The two second force-bearing winding wheels are respectively sleeved on both ends of the third rotating shaft to form a rotatable connection. The two second drive ropes pass around the two second force-bearing winding wheels in opposite winding directions, and the two second drive ropes are respectively connected and fixed to the two second force-bearing winding wheels. The pulling of the two second drive ropes is used to drive the third arm segment to rotate in different directions.

[0023] In one embodiment, the second rope drive mechanism further includes a No. 21 rope winding wheel, a No. 22 rope winding wheel, a No. 23 rope winding wheel, a No. 24 rope winding wheel, and a No. 25 rope winding wheel; two No. 21 rope winding wheels are disposed on the first rotating shaft; two No. 22 rope winding wheels are disposed on the second front rotating shaft; two No. 23 rope winding wheels and two No. 24 rope winding wheels are respectively disposed on two opposite surfaces of the second arm segment, and the central axis of the two No. 23 rope winding wheels and the central axis of the two No. 24 rope winding wheels are both aligned with the central axis of the third rotating shaft; two No. 25 rope winding wheels are respectively disposed at both ends of the second rear rotating shaft; the second drive rope passes around the No. 21 rope winding wheel, the No. 22 rope winding wheel, the No. 23 rope winding wheel, the No. 24 rope winding wheel, the No. 25 rope winding wheel, and the second force-bearing rope winding wheel in an alternating winding direction.

[0024] In one embodiment, the third rope drive mechanism includes a first bevel gear, a second bevel gear, a third force-bearing winding wheel, a third drive rope, and a transmission module; the first bevel gear is disposed on the third arm segment, the second bevel gear is connected and fixed to the gripper, the first bevel gear and the second bevel gear are arranged perpendicularly to each other and mesh; the two third force-bearing winding wheels are fixedly connected to both ends of the third rotating shaft, the two first drive ropes pass over the two third force-bearing winding wheels in opposite winding directions, and the two third drive ropes are respectively connected and fixed to the two third force-bearing winding wheels; one of the third force-bearing winding wheels is connected to the first bevel gear through the transmission module, so that the pulling of the two third drive ropes drives the gripper to rotate in different directions.

[0025] In one embodiment, the third rope drive mechanism further includes a No. 31 rope winding wheel, a No. 32 rope winding wheel, a No. 33 rope winding wheel, a No. 34 rope winding wheel, and a No. 35 rope winding wheel; two No. 31 rope winding wheels are disposed on the first rotating shaft; two No. 32 rope winding wheels are disposed on the second front rotating shaft; two No. 33 rope winding wheels and two No. 34 rope winding wheels are respectively disposed on two opposite surfaces of the second arm segment, and the central axis of the two No. 33 rope winding wheels and the central axis of the two No. 34 rope winding wheels are both aligned with the central axis of the third rotating shaft; two No. 35 rope winding wheels are respectively disposed on the... The second rear rotating shaft has two ends; the third drive rope wraps around the third-first winding wheel, the third-second winding wheel, the third-third winding wheel, the third-fourth winding wheel, the third-fifth winding wheel, and the third force-bearing winding wheel in an alternating winding direction; the transmission module includes a first transmission winding wheel, a second transmission winding wheel, and a transmission rope; the first transmission winding wheel is coaxially connected and fixed to one of the third force-bearing winding wheels; the second transmission winding wheel is coaxially connected and fixed to the first bevel gear; the transmission rope is wound in a figure-eight shape around the first transmission winding wheel and the second transmission winding wheel.

[0026] In one embodiment, encoders are provided at the rotatable connection between the first arm segment and the second arm segment, the rotatable connection between the second arm segment and the third arm segment, and the rotatable connection between the gripper and the third arm segment.

[0027] The beneficial effects of this invention are as follows:

[0028] 1. The three-degree-of-freedom rope-driven direct-drive serial wrist designed in this invention significantly reduces the difficulty of parts and installation.

[0029] 2. The three-degree-of-freedom rope-driven direct-drive serial wrist designed in this invention can effectively reduce the difficulty of forward and inverse kinematics modeling.

[0030] 3. The rotary joint designed in this invention has gear meshing, which improves accuracy and increases the rigidity of the wrist structure.

[0031] 4. The integrated encoder improves joint precision while ensuring a compact structure. Attached Figure Description

[0032] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the structure provided in an embodiment of the present invention;

[0034] Figure 2 yes Figure 1 A schematic diagram of the structure after some components have been removed;

[0035] Figure 3 yes Figure 1 A schematic diagram of the transmission structure of the first rope-driven mechanism;

[0036] Figure 4 yes Figure 1 A schematic diagram of the transmission structure of the second rope drive mechanism;

[0037] Figure 5 yes Figure 4 A schematic diagram of the winding method of the first and second drive ropes;

[0038] Figure 6 yes Figure 4 A schematic diagram of the winding method of the second drive rope in the middle;

[0039] Figure 7 yes Figure 1 A schematic diagram of the transmission structure of the third rope drive mechanism;

[0040] Figure 8 yes Figure 7 A schematic diagram of the winding method of the first third drive rope;

[0041] Figure 9 yes Figure 7 A schematic diagram of the winding method of the second and third drive ropes;

[0042] Figure 10 yes Figure 1 A schematic diagram of the encoder setting location.

[0043] The attached figures are labeled as follows:

[0044] 10. First arm section; 11. First gear plate; 12. Positioning shaft;

[0045] 20. Second arm section; 21. Second front gear plate; 22. Second rear gear plate;

[0046] 30. Third arm segment; 31. Third gear plate;

[0047] 40. Gripper;

[0048] 50. First rope drive mechanism; 51. First force-bearing winding sheave; 52. First drive rope; 531. First winding sheave; 532. First and second winding sheaves;

[0049] 60. Second rope drive mechanism; 61. Second force-bearing winding sheave; 62. Second drive rope; 631. No. 21 winding sheave; 632. No. 22 winding sheave; 633. No. 23 winding sheave; 634. No. 24 winding sheave; 635. No. 25 winding sheave;

[0050] 70. Third rope drive mechanism; 71. Third force-bearing rope pulley; 72. Third drive rope; 731. Rope pulley No. 1; 732. Rope pulley No. 2; 733. Rope pulley No. 33; 734. Rope pulley No. 4; 735. Rope pulley No. 5; 741. First bevel gear; 742. Second bevel gear; 75. Transmission module; 751. First transmission rope pulley; 752. Second transmission rope pulley; 753. Transmission rope;

[0051] 811. First connecting plate; 812. Second connecting plate; 82. Encoder;

[0052] 91. First pivot; 921. Second front pivot; 922. Second rear pivot; 93. Third pivot. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0054] This invention provides a three-degree-of-freedom cable-driven direct-drive serial wrist based on gear constraints, and its implementation is as follows: Figure 1As shown, the device includes a first arm segment 10, a second arm segment 20, a third arm segment 30, a gripper 40, a first rope drive mechanism 50, a second rope drive mechanism 60, and a third rope drive mechanism 70. The first arm segment 10 and the first end of the second arm segment 20 are connected by a gear joint rotation structure, and the second end of the second arm segment 20 and the first end of the third arm segment 30 are also connected by a gear joint rotation structure. The second end of the third arm segment 30 is rotatably connected to the gripper 40, and the rotation axes of the first end of the second arm segment 20, the first end of the third arm segment 30, and the gripper 40 are all perpendicular to each other. The first rope drive mechanism 50, the second rope drive mechanism 60, and the third rope drive mechanism 70 are used to independently control the rotation of the second arm segment 20, the third arm segment 30, and the gripper 40, respectively.

[0055] With this configuration, since the first arm segment 10 and the first end of the second arm segment 20 are connected by a gear joint rotation structure, and the second end of the second arm segment 20 and the first end of the third arm segment 30 are connected by a gear joint rotation structure, this structure not only improves the rotation control accuracy but also enhances the rigidity of the wrist structure. Furthermore, the first rope drive mechanism 50, the second rope drive mechanism 60, and the third rope drive mechanism 70 are used to independently control the rotation of the second arm segment 20, the third arm segment 30, and the gripper 40, respectively, which also significantly reduces the difficulty of parts and installation.

[0056] like Figure 1 and Figure 2 As shown, in this embodiment, the first arm segment 10 is provided with two separate, oppositely arranged first gear plates 11, and the first end of the second arm segment 20 is provided with two separate, oppositely arranged second front gear plates 21. The two first gear plates 11 mesh with the two second front gear plates 21 respectively. The three-degree-of-freedom rope-driven direct-drive serial wrist also includes a first connecting plate 811. The two first connecting plates 811 are respectively located on the outer sides of the first arm segment 10 and the second arm segment 20. A first rotating shaft 91 and a second front rotating shaft 921 are rotatably connected between the two sides of the two first connecting plates 811. The first rotating shaft 91 passes through the two first gear plates 11 to form a fixed connection, and the second front rotating shaft 921 passes through the two second front gear plates 21 to form a fixed connection. Therefore, by adopting this configuration, the gear joint rotation structure between the first arm segment 10 and the second arm segment 20 can be formed.

[0057] like Figures 1 to 3 As shown, this embodiment sets the first rope drive mechanism 50 to include a first force-receiving winding wheel 51 and a first drive rope 52. The two first force-receiving winding wheels 51 are connected and fixed on the second front rotating shaft 921. The two first drive ropes 52 pass around the two first force-receiving winding wheels 51 in opposite winding directions, and the two first drive ropes 52 are respectively connected and fixed to the two first force-receiving winding wheels 51. The pulling of the two first drive ropes 52 is used to drive the second arm segment 20 to rotate in different directions.

[0058] With this configuration, if pulling the first drive rope 52 can control one of the first force-bearing winding wheels 51 to rotate clockwise, then the second arm segment 20 can be driven to rotate clockwise. Similarly, if pulling the second drive rope 52 can control the other first force-bearing winding wheel 51 to rotate counterclockwise, then the second arm segment 20 can be driven to rotate counterclockwise, thus achieving the purpose of bidirectional rotation control switching of the second arm segment 20.

[0059] like Figures 1 to 3 As shown, in this embodiment, the first arm segment 10 is provided with a positioning shaft 12, and the axial direction of the positioning shaft 12 is the same as the axial direction of the first rotating shaft 91; the first rope drive mechanism 50 also includes a first winding wheel 531 and a second winding wheel 532. The two first winding wheels 531 are provided on the positioning shaft 12, and the two first winding wheels 532 are provided on the first rotating shaft 91. The first drive rope 52 passes around the first winding wheel 531, the first winding wheel 532 and the first force-bearing winding wheel 51 in an alternating winding direction.

[0060] like Figure 1 and Figure 3 As shown, at this time, the first drive rope 52 near the top passes over the first winding wheel 531 near the top, then passes under the first and second winding wheels 532, and finally passes over the top of the first force winding wheel 51, and is connected and fixed to the first force winding wheel 51. Therefore, once the first drive rope 52 is pulled to the left, the first force winding wheel 51 and the second arm segment 20 will rotate counterclockwise in sync.

[0061] Similarly, such as Figure 1 and Figure 3 As shown, at this time, the first drive rope 52 near the bottom passes under the first winding wheel 531 near the bottom, then passes over the top of the first and second winding wheels 532, and finally passes under the first force winding wheel 51 and is connected and fixed to the first force winding wheel 51. Therefore, once the first drive rope 52 is pulled to the left, the first force winding wheel 51 and the second arm segment 20 will rotate clockwise synchronously.

[0062] like Figure 1 and Figure 2As shown, in this embodiment, the second end of the second arm segment 20 is provided with two separate and oppositely arranged second rear gear plates 22, and the first end of the third arm segment 30 is provided with two separate and oppositely arranged third gear plates 31. The two second rear gear plates 22 mesh with the two third gear plates 31 respectively. The three-degree-of-freedom rope-driven direct-drive series wrist also includes a second connecting plate 812. The two sides of the second connecting plate 812 are respectively located between the two second rear gear plates 22 and between the two third gear plates 31. The two sides of the second connecting plate 812 are respectively provided with a second rear rotating shaft 922 and a third rotating shaft 93. The second rear rotating shaft 922 passes through the two second rear gear plates 22 to form a fixed connection, and the third rotating shaft 93 passes through the two third gear plates 31 to form a rotatable connection. Therefore, after adopting this configuration, the gear joint rotation structure between the second arm segment 20 and the third arm segment 30 can be formed.

[0063] like Figure 1 , Figure 2 ,as well as Figures 4 to 6 As shown, this embodiment provides a second rope drive mechanism 60 including a second force-bearing winding wheel 61 and a second drive rope 62. The two second force-bearing winding wheels 61 are respectively connected and fixed to the outside of the two third gear plates 31. The two second force-bearing winding wheels 61 are respectively sleeved on both ends of the third rotating shaft 93 to form a rotatable connection. The two second drive ropes 62 are respectively wound around the two second force-bearing winding wheels 61 in opposite winding directions, and the two second drive ropes 62 are respectively connected and fixed to the two second force-bearing winding wheels 61. The pulling of the two second drive ropes 62 is used to drive the third arm segment 30 to rotate in different directions.

[0064] With this configuration, if pulling the first second drive rope 62 can control one of the second force-bearing winding wheels 61 to rotate clockwise, then the third arm segment 30 can be driven to rotate clockwise. Similarly, if pulling the second second drive rope 62 can control the other second force-bearing winding wheel 61 to rotate counterclockwise, then the third arm segment 30 can be driven to rotate counterclockwise, thus achieving the purpose of bidirectional rotation control switching of the third arm segment 30.

[0065] like Figure 1 , Figure 2 ,as well as Figures 4 to 6As shown, this embodiment of the second rope drive mechanism 60 also includes a second rope winding wheel 631, a second rope winding wheel 632, a second rope winding wheel 633, a second rope winding wheel 634, and a second rope winding wheel 635; the two second rope winding wheels 631 are mounted on the first rotating shaft 91; the two second rope winding wheels 632 are mounted on the second front rotating shaft 921; the two second rope winding wheels 633 and the two second rope winding wheels 634 are respectively mounted on the two opposite surfaces of the second arm segment 20. The central axis of the two No. 2 and No. 3 winding pulleys 633 and the central axis of the two No. 2 and No. 4 winding pulleys 634 are aligned with the central axis of the third rotating shaft 93; the two No. 2 and No. 5 winding pulleys 635 are respectively located at both ends of the second rear rotating shaft 922; the second drive rope 62 passes over the No. 21 winding pulley 631, No. 22 winding pulley 632, No. 23 winding pulley 633, No. 24 winding pulley 634, No. 25 winding pulley 635 and the second force-bearing winding pulley 61 in an alternating winding direction.

[0066] like Figure 1 and Figure 5 As shown, at this time, the second drive rope 62 passes sequentially over the first winding wheel 631, below the second winding wheel 632, behind the second winding wheel 633, in front of the second winding wheel 634, behind the second winding wheel 635, and in front of the second force-bearing winding wheel 61, and is connected and fixed to the second force-bearing winding wheel 61. Therefore, once the second drive rope 62 is pulled to the left, the second force-bearing winding wheel 61 and the third arm segment 30 will rotate clockwise synchronously.

[0067] Similarly, such as Figure 1 and Figure 6 As shown, at this time, another second drive rope 62 passes under the second first winding rope 631, above the second second winding rope 632, in front of the second third winding rope 633, behind the second fourth winding rope 634, in front of the second fifth winding rope 635, and behind the second force winding rope 61, and is connected and fixed to the second force winding rope 61. Therefore, once the second drive rope 62 is pulled to the left, the second force winding rope 61 and the third arm segment 30 will rotate counterclockwise synchronously.

[0068] like Figure 1 , Figure 2 ,as well as Figures 7 to 9As shown, this embodiment includes a third rope drive mechanism 70 comprising a first bevel gear 741, a second bevel gear 742, a third force-bearing winding wheel 71, a third drive rope 72, and a transmission module 75. The first bevel gear 741 is mounted on the third arm segment 30, and the second bevel gear 742 is connected and fixed to the gripper 40. The first bevel gear 741 and the second bevel gear 742 are arranged perpendicularly to each other and mesh with each other. The two third force-bearing winding wheels 71 are fixedly connected to both ends of the third rotating shaft 93. The two first drive ropes 52 are wound around the two third force-bearing winding wheels 71 in opposite directions, and the two third drive ropes 72 are respectively connected and fixed to the two third force-bearing winding wheels 71. One of the third force-bearing winding wheels 71 is connected to the first bevel gear 741 via the transmission module 75, so that the pulling of the two third drive ropes 72 drives the gripper 40 to rotate in different directions.

[0069] With this configuration, if pulling the first third drive rope 72 can control one of the third force-bearing winding wheels 71 to rotate clockwise, then the transmission module 75 can control the first bevel gear 741, the second bevel gear 742, and the gripper 40 to rotate in one direction. Similarly, if pulling the second third drive rope 72 can control the other third force-bearing winding wheel 71 to rotate counterclockwise, then the transmission module 75 can control the first bevel gear 741, the second bevel gear 742, and the gripper 40 to rotate in the other direction, thus achieving the purpose of switching the bidirectional rotation control of the gripper 40.

[0070] like Figure 1 , Figure 2 ,as well as Figures 7 to 9As shown, this embodiment of the third rope drive mechanism 70 also includes a No. 31 rope winding wheel 731, a No. 32 rope winding wheel 732, a No. 333 rope winding wheel 733, a No. 34 rope winding wheel 734, and a No. 35 rope winding wheel 735; the two No. 31 rope winding wheels 731 are disposed on the first rotating shaft 91; the two No. 32 rope winding wheels 732 are disposed on the second front rotating shaft 921; the two No. 33 rope winding wheels 733 and the two No. 34 rope winding wheels 734 are respectively disposed on two opposite surfaces of the second arm segment 20, and the central axis of the two No. 33 rope winding wheels 733 and the central axis of the two No. 34 rope winding wheels 734 are both aligned with the central axis of the third rotating shaft 93; the two No. 35 rope winding wheels 735 are respectively disposed on the second front rotating shaft 921. The rear rotating shaft 922 has two ends; the third drive rope 72 wraps around the third winding wheel 731, the third winding wheel 732, the third winding wheel 733, the third winding wheel 734, the third winding wheel 735 and the third force winding wheel 71 in an alternating winding direction; the transmission module 75 includes a first transmission winding wheel 751, a second transmission winding wheel 752 and a transmission rope 753; the first transmission winding wheel 751 is coaxially connected and fixed to one of the third force winding wheels 71; the second transmission winding wheel 752 is coaxially connected and fixed to the first bevel gear 741; the transmission rope 753 is wound in a figure-eight shape around the first transmission winding wheel 751 and the second transmission winding wheel 752.

[0071] like Figures 7 to 9 As shown, the third drive rope 72 passes sequentially above the first winding wheel 731, below the second winding wheel 732, behind the third winding wheel 733, in front of the fourth winding wheel 734, to the left of the fifth winding wheel 735, and to the right of the third force-bearing winding wheel 71, and is connected and fixed to the third force-bearing winding wheel 71. Therefore, once the third drive rope 72 is pulled to the left, the third force-bearing winding wheel 71 will rotate clockwise. Furthermore, since the third rotating shaft 93, the two third force-bearing winding wheels 71, and the first transmission winding wheel 751 are synchronously rotating, the first transmission winding wheel 751 will also rotate clockwise, thereby driving the subsequent transmission rope 753, the second transmission winding wheel 752, the first bevel gear 741, the second bevel gear 742, and the gripper 40 to rotate.

[0072] Similarly, at this time, another third drive rope 72 passes sequentially from below the third-first winding wheel 731, above the third-second winding wheel 732, in front of the third-third winding wheel 733, behind the third-fourth winding wheel 734, to the left of the third-fifth winding wheel 735, and to the right of the third force-bearing winding wheel 71, and is connected and fixed to the third force-bearing winding wheel 71. Therefore, once the third drive rope 72 is pulled to the left, the third force-bearing winding wheel 71 will rotate counterclockwise. And since the third rotating shaft 93, the two third force-bearing winding wheels 71, and the first transmission winding wheel 751 are synchronously rotating structures, the first transmission winding wheel 751 will also rotate counterclockwise at this time, thereby driving the subsequent transmission rope 753, the second transmission winding wheel 752, the first bevel gear 741, the second bevel gear 742, and the gripper 40 to rotate in another direction.

[0073] like Figure 10 As shown, in this embodiment, encoders 82 are provided at the rotatable connection between the first arm segment 10 and the second arm segment 20, the rotatable connection between the second arm segment 20 and the third arm segment 30, and the rotatable connection between the gripper 40 and the third arm segment 30.

[0074] Since the rope will elongate under axial force, and real ropes are not ideal ropes, the axial force of the rope may be different at different positions. This will cause the motion output deviation due to the unmeasurable length change of the rope when driving the joint to rotate. Therefore, this embodiment integrates an encoder 82 at the above-mentioned rotating connection.

[0075] Specifically, two encoders 82 are provided at the point where the first arm segment 10 and the second arm segment 20 rotate. These are AS5047P magnetic encoders with an accuracy of 0.022°. Since there is already gear constraint between the joints, the two AS5047P magnetic encoders are distributed on both sides, which can eliminate mechanical errors caused by gear processing to the greatest extent. In addition, the sampling timing of the two magnetic encoders is also consistent.

[0076] The remaining encoders, 82, use King Kong Technology's 16-bit hollow magnetic encoder, with an accuracy of 0.0055°.

[0077] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A three-degree-of-freedom cable-driven direct-drive serial wrist based on gear constraints, characterized in that, It includes a first arm segment, a second arm segment, a third arm segment, a gripper, a first rope drive mechanism, a second rope drive mechanism, and a third rope drive mechanism; The first arm segment and the first end of the second arm segment are connected by a gear joint rotation structure, the second end of the second arm segment and the first end of the third arm segment are connected by a gear joint rotation structure, the second end of the third arm segment is rotatably connected to the gripper, and the rotation axis of the first end of the second arm segment, the rotation axis of the first end of the third arm segment, and the rotation axis of the gripper are all perpendicular to each other. The first rope drive mechanism, the second rope drive mechanism, and the third rope drive mechanism are respectively used to independently control the rotation of the second arm segment, the third arm segment, and the gripper. The first arm segment is provided with two separate and oppositely arranged first gear plates, and the first end of the second arm segment is provided with two separate and oppositely arranged second front gear plates, and the two first gear plates respectively mesh with the two second front gear plates; The three-degree-of-freedom rope-driven direct-drive serial wrist also includes a first connecting plate. The two first connecting plates are respectively disposed on the outer sides of the first arm segment and the second arm segment. A first rotating shaft and a second front rotating shaft are respectively rotatably connected between the two sides of the two first connecting plates. The first rotating shaft passes through the two first gear plates to form a fixed connection, and the second front rotating shaft passes through the two second front gear plates to form a fixed connection. The second end of the second arm segment is provided with two separate and oppositely arranged second rear gear plates, and the first end of the third arm segment is provided with two separate and oppositely arranged third gear plates, and the two second rear gear plates respectively mesh with the two third gear plates; The three-degree-of-freedom rope-driven direct-drive serial wrist also includes a second connecting plate. The two sides of the second connecting plate are respectively located between the two second rear gear plates and between the two third gear plates. The two sides of the second connecting plate are respectively provided with a second rear rotating shaft and a third rotating shaft. The second rear rotating shaft passes through the two second rear gear plates to form a fixed connection, and the third rotating shaft passes through the two third gear plates to form a rotatable connection. The third rope drive mechanism includes a first bevel gear, a second bevel gear, a third force-bearing winding wheel, a third drive rope, and a transmission module; The first bevel gear is disposed on the third arm segment, and the second bevel gear is connected and fixed to the gripper. The first bevel gear and the second bevel gear are arranged perpendicular to each other and mesh with each other. The two third force-bearing winding rope wheels are fixedly connected to both ends of the third rotating shaft. The two first driving ropes of the first rope drive mechanism pass around the two third force-bearing winding rope wheels in opposite winding directions, and the two third driving ropes are respectively connected and fixed to the two third force-bearing winding rope wheels. One of the third force-bearing rope pulleys is connected to the first bevel gear via the transmission module, so that the pulling of the two third drive ropes drives the gripper to rotate in different directions.

2. The three-degree-of-freedom rope-driven direct-drive serial wrist according to claim 1, characterized in that, The first rope drive mechanism includes a first force-bearing winding wheel and a first drive rope. The two first force-bearing winding wheels are connected and fixed to the second front rotating shaft. The two first drive ropes pass around the two first force-bearing winding wheels in opposite winding directions, and the two first drive ropes are respectively connected and fixed to the two first force-bearing winding wheels. The pulling of the two first drive ropes is used to drive the second arm segment to rotate in different directions.

3. The three-degree-of-freedom rope-driven direct-drive serial wrist according to claim 2, characterized in that, The first arm segment is provided with a positioning shaft, and the axial direction of the positioning shaft is the same as the axial direction of the first rotating shaft; The first rope drive mechanism further includes a first rope winding wheel and a second rope winding wheel. The two first rope winding wheels are disposed on the positioning shaft, and the two first rope winding wheels are disposed on the first rotating shaft. The first drive rope passes around the first rope winding wheel, the first rope winding wheel and the first force-bearing rope winding wheel in an alternating winding direction.

4. The three-degree-of-freedom rope-driven direct-drive serial wrist as described in claim 1, characterized in that, The second rope-driven mechanism includes a second force-bearing winding wheel and a second drive rope. The two second force-bearing winding wheels are respectively connected and fixed to the outside of the two third gear plates. The two second force-bearing winding wheels are respectively sleeved on both ends of the third rotating shaft to form a rotatable connection. The two second drive ropes pass around the two second force-bearing winding wheels in opposite winding directions, and the two second drive ropes are respectively connected and fixed to the two second force-bearing winding wheels. The pulling of the two second drive ropes is used to drive the third arm segment to rotate in different directions.

5. The three-degree-of-freedom rope-driven direct-drive serial wrist according to claim 4, characterized in that, The second rope drive mechanism also includes rope winding pulley No. 21, rope winding pulley No. 22, rope winding pulley No. 23, rope winding pulley No. 24 and rope winding pulley No. 25; The two No. 21 rope-winding wheels are mounted on the first rotating shaft; The two No. 22 rope winding pulleys are mounted on the second front rotating shaft; The two second and third rope winding wheels and the two second and fourth rope winding wheels are respectively located on the two opposite surfaces of the second arm segment. The central axis of the two second and third rope winding wheels and the central axis of the two second and fourth rope winding wheels are consistent with the central axis of the third rotating shaft. The two No. 25 rope winding pulleys are respectively located at both ends of the second rear rotating shaft; The second drive rope wraps around the second-first winding wheel, the second-second winding wheel, the second-third winding wheel, the second-fourth winding wheel, the second-fifth winding wheel, and the second force-bearing winding wheel in an alternating winding direction.

6. The three-degree-of-freedom rope-driven direct-drive serial wrist according to claim 1, characterized in that, The third rope drive mechanism also includes rope winding pulley No. 31, rope winding pulley No. 32, rope winding pulley No. 33, rope winding pulley No. 34 and rope winding pulley No. 35; The two No. 31 rope-winding pulleys are mounted on the first rotating shaft; The two No. 32 rope winding pulleys are mounted on the second front rotating shaft; The two No. 3 rope winding wheels and the two No. 4 rope winding wheels are respectively located on the two opposite surfaces of the second arm segment. The central axis of the two No. 3 rope winding wheels and the central axis of the two No. 4 rope winding wheels are consistent with the central axis of the third rotating shaft. The two No. 35 rope winding pulleys are respectively located at both ends of the second rear rotating shaft; The third drive rope wraps around the No. 31 winding wheel, the No. 32 winding wheel, the No. 33 winding wheel, the No. 34 winding wheel, the No. 35 winding wheel, and the third force-bearing winding wheel in an alternating winding direction; The transmission module includes a first transmission winding wheel, a second transmission winding wheel, and a transmission rope; The first transmission winding wheel is coaxially connected and fixed to one of the third force-receiving winding wheels; The second transmission rope wheel is coaxially connected and fixed to the first bevel gear; The transmission rope is wound in a figure-eight shape around the first transmission winding wheel and the second transmission winding wheel.

7. The three-degree-of-freedom cable-driven direct-drive serial wrist according to claim 1, characterized in that, Encoders are provided at the rotatable connection points of the first arm segment and the second arm segment, the rotatable connection points of the second arm segment and the third arm segment, and the rotatable connection points of the gripper and the third arm segment.

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