Two-degree-of-freedom bionic wrist joint robot with gear connecting rod decoupling drive

Abstract

This invention relates to a two-degree-of-freedom bionic wrist joint robot with decoupled gear and linkage drive. It includes a mounting bracket with a central connecting plate at the top, a moving platform comprising platforms A and B, a linkage chain, a first gear transmission system, a second gear transmission system, and a first and second hollow rotary actuators with a coaxial nested design. The first rotary actuator transmits rotational motion to the universal joint of the moving platform via bevel teeth A and B, and gears A, B, and C of the first gear transmission system, causing the moving platform to rotate around the rotating hole A of the mounting bracket. The second hollow rotary actuator, via bevel teeth C and D of the second gear transmission system, and in conjunction with the parallelogram-shaped linkages A, B, and C and L-shaped connectors A and B, causes platform A to rotate around the center of the universal joint and parallel to the axis of rotation D. This invention achieves a wide range of two-degree-of-freedom rotational motion of the wrist, and its compact structure allows it to perfectly adapt to the narrow joint mounting space of prostheses or humanoid robots.

Description

Technical Field

[0001] This invention relates to the field of robot design, and in particular to the design of a two-degree-of-freedom bionic wrist joint robot with decoupled gear and linkage drive. Background Technology

[0002] The statements in this section are merely background information relating to this disclosure, and these statements may constitute prior art. In the process of developing this invention, the inventors discovered at least the following problems in the prior art.

[0003] In the fields of prostheses, rehabilitation equipment, and bionic robots (especially humanoid robots), the wrist joint, as a crucial link connecting the forearm and the end effector (or bionic hand), directly determines the flexibility, precision, and naturalness of the robot's operation. An ideal bionic wrist joint needs at least two rotational degrees of freedom to meet the multi-dimensional posture adjustment requirements in complex scenarios. However, traditional wrist joint rotational structures face the following technical bottlenecks in practical applications:

[0004] First, there is a contradiction between structural compactness and driving capability. Existing multi-degree-of-freedom wrist joints mostly employ serial mechanical linkages or conventional parallel mechanisms, such as the patent application number 202511327350.3 entitled "A Bionic Wrist Joint Based on Rope Drive." Their drive motors and transmission components are typically externally mounted or distributed, resulting in a relatively bulky overall structure with large axial and lateral dimensions. This design makes it difficult to balance high driving capability, bidirectional rotational accuracy, and lightweight design within the extremely limited and narrow joint mounting space of prostheses or humanoid robots, severely restricting the integration and anthropomorphic appearance of bionic robots.

[0005] Secondly, there is the complexity of motion decoupling and control. Some existing compact wrist joints, such as the one described in patent application number 202110538915.8, entitled "A Bionic Wrist Joint Based on an Asymmetric 3-RRR Parallel Mechanism," employ asymmetric transmission or complex transmission designs to reduce size. This not only leads to uneven force distribution on the joint and low transmission efficiency, but also results in severe motion coupling between the two driving directions. This strong coupling characteristic makes the forward and inverse kinematic calculations of the wrist joint extremely cumbersome, and the control algorithm complex, making it difficult to meet the multi-dimensional, precise, and independent real-time rotational control requirements of the wrist joint in bionic movements.

[0006] Finally, there are issues with limited range of motion and chain interference. While some existing structures have achieved miniaturization, this often comes at the cost of limited range of motion, enabling only unidirectional movement or compound movements at very small angles. When attempting to increase the range of rotation, the internal transmission chains are prone to spatial interference, resulting in limited movement postures and an inability to achieve flexible wrist rotation over a wide range, making it difficult to meet the large posture adjustment needs in rehabilitation training or complex tasks.

[0007] In summary, how to break the mutual constraints between "structural compactness", "motion decoupling control" and "large range of motion" in traditional wrist joints, and design a two-degree-of-freedom wrist joint structure with high space utilization, simple kinematic calculation and flexible rotation has become an urgent technical problem to be solved in the field of prosthetics and bionic robots. Summary of the Invention

[0008] In view of the above problems, the purpose of this invention is to solve some of the problems in the prior art, or at least alleviate these problems.

[0009] A two-DOF bionic wrist joint robot with decoupled gear and linkage drive includes:

[0010] The mounting bracket has an intermediate connecting plate fixed at the top of its frame; the upper end of the intermediate connecting plate has a rotating hole A and is connected to the rotating shaft C through a rotating joint.

[0011] The actuator includes a second hollow rotary actuator and a first rotary actuator, which are fixed from top to bottom at the middle of the frame of the mounting bracket; the rotation shaft of the first rotary actuator passes through the hollow rotation shaft of the second hollow rotary actuator.

[0012] The moving platform includes a U-shaped platform A and a platform B, as well as a universal joint, an L-shaped connector A, and an L-shaped connector B. The tops of the platforms A and B are connected by a revolute joint. The two ends of the platform A are respectively connected to the first ends of the L-shaped connectors A and B with the same structure through coaxial revolute joints. The first end of the middle section of the universal joint is connected to the rotating hole A through a revolute joint, and its two ends are respectively connected to the two ends of the platform B through coaxial revolute joints.

[0013] The linkage chain includes connecting rods A, B, and C with the same structure; the first ends of connecting rods A and B are respectively connected to the second ends of L-shaped connectors A and B via revolute joints, and the second ends of both are respectively connected to the two ends of connecting rod C via revolute joints; the axes of the revolute joints on connecting rods A, B, and C are all parallel to each other and together with L-shaped connectors A and B form a parallelogram relationship;

[0014] The first gear transmission system includes gear A, gear C, bevel gear A, and bevel gear B; gear A is fixedly connected to the second end of the middle section of the universal joint; the side of gear C is fixedly connected to the mounting end face of bevel gear A, and together they are fixedly connected to the rotating shaft C; bevel gear B meshes with bevel gear A, and its mounting end face is fixedly connected to the rotating shaft of the first rotary driver; the first rotary driver drives gear A to rotate through bevel gear B, bevel gear A, and gear C;

[0015] The second gear transmission system includes bevel gear C and bevel gear D; the mounting end face of bevel gear C is fixed to the middle section of connecting rod C; bevel gear D is a hollow structure that meshes with bevel gear C, and its mounting end face is fixed to the hollow rotating shaft of the second hollow rotary actuator.

[0016] Preferably, the axes of the revolute joints on platform A are perpendicular to each other; the axes of the revolute joints on platform B are perpendicular to each other; and the top of platform A is used to connect to an end effector.

[0017] Preferably, the axes of the rotating joints on the universal joint are perpendicular to each other and intersect; the axes of the rotating joints on the L-shaped connector A are perpendicular to each other and intersect at a point; the axes of the rotating joints on the L-shaped connector B are perpendicular to each other and intersect at a point.

[0018] Preferably, the axes of the rotating hole A and the rotating shaft C are parallel.

[0019] Furthermore, the first gear transmission system also includes gear B, which meshes with gear A and gear C respectively; the intermediate connecting plate is also connected to shaft B via a rotating pair, and gear B is fixed to shaft B; the axes of shaft B, rotating hole A and shaft C are parallel.

[0020] Furthermore, gears A, B, and C are all cylindrical spur teeth; gear A is a half-tooth.

[0021] Furthermore, the mounting bracket is also provided with a rotating shaft D; the frame of the mounting bracket is connected to the rotating shaft D via a rotating joint; the middle section of the connecting rod C is connected to the rotating shaft D via a rotating joint; the axis of the rotating shaft D is perpendicular to the axis of the rotating hole A and the axis of the rotating shaft C.

[0022] Furthermore, the rotation axes of the bevel tooth A and the bevel tooth B are perpendicular to each other; the rotation axes of the bevel tooth C and the bevel tooth D are perpendicular to each other.

[0023] The present invention has the following beneficial effects:

[0024] (1) By using the gear transmission system and the connecting rod, the two rotational degrees of freedom of the moving platform are decoupled, which makes the kinematic calculation simple and the control easy to implement;

[0025] (2) Large range of rotation and flexible movement posture. The two branches operate independently, that is, the first gear transmission system and the parallel connecting rod branch do not interfere with each other, which can realize a large range of two-degree-of-freedom rotational movements of the wrist;

[0026] (3) Compact structure and high space utilization. Through the coaxial nesting design of the second hollow rotary actuator and the first rotary actuator, combined with the gear transmission system, the axial and lateral dimensions of the device are greatly reduced, making it perfectly adaptable to the narrow joint installation space of prostheses or humanoid robots. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the present invention;

[0028] Figure 2 This is a schematic diagram of the mounting bracket of the present invention;

[0029] Figure 3 This is a schematic diagram of the structure of the moving platform of the present invention;

[0030] Figure 4 This is a schematic diagram of the connecting rod chain of the present invention;

[0031] Figure 5 This is a schematic diagram showing the connection between the first gear transmission system and the mounting bracket of the present invention;

[0032] Figure 6 This is a schematic diagram of the structure of the first gear transmission system of the present invention;

[0033] Figure 7 This is a schematic diagram of the second gear transmission system structure of the present invention;

[0034] Figure 8 This is a schematic diagram illustrating one possible use of the present invention.

[0035] Wherein: 1-Moving platform; 11-Platform A; 12-Platform B; 13-Universal shaft; 14-L-shaped connector A; 15-L-shaped connector B; 2-Connecting rod chain; 21-Connecting rod A; 22-Connecting rod B; 23-Connecting rod C; 3-First gear transmission system; 31-Gear A; 32-Gear B; 33-Gear C; 34-Bevel gear A; 35-Bevel gear B; 4-Second gear transmission system; 41-Bevel gear C; 42-Bevel gear D; 5-Mounting bracket; 51-Intermediate connecting plate; 52-Rotating hole A; 53-Rotating shaft B; 54-Rotating shaft C; 55-Rotating shaft D; 6-First rotary actuator; 7-Second hollow rotary actuator. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings. The embodiments of the present invention are only used to illustrate the present invention and not to limit the present invention. Various substitutions and modifications made based on ordinary technical knowledge and common practices in the art without departing from the technical concept of the present invention should be included within the scope of the present invention.

[0037] To address the aforementioned technical challenges, the applicant designed a two-degree-of-freedom bionic wrist joint robot with decoupled gear and linkage drive, such as... Figures 1 to 8 As shown, it includes:

[0038] Mounting bracket 5 is a frame structure, such as Figure 2 As shown, a middle connecting plate 51 is fixed at the top of its frame. The lower end can be connected to a humanoid robot, a human arm, etc., such as... Figure 8 As shown. The upper end of the intermediate connecting plate 51 is provided with a rotating hole A52, and is connected to the rotating shaft C54 through a rotating joint.

[0039] The actuator includes a second hollow rotary actuator 7 and a first rotary actuator 6, which are fixed from top to bottom to the middle of the frame of the mounting bracket 5; they adopt a coaxial nesting design, and the rotation shaft of the first rotary actuator 6 passes through the hollow rotation shaft of the second hollow rotary actuator 7.

[0040] Dynamic platform 1, such as Figure 3 As shown, the system includes a U-shaped platform A11 and a platform B12, as well as a universal joint 13, an L-shaped connector A14, and an L-shaped connector B15. The tops of the platforms A11 and B12 are connected by a revolute joint. The two ends of the platform A11 are respectively connected to the first ends of the L-shaped connectors A14 and B15, which have the same structure, through coaxial revolute joints. The first end of the middle section of the universal joint 13 is connected to the rotating hole A through a revolute joint, and its two ends are respectively connected to the two ends of the platform B12 through coaxial revolute joints.

[0041] Linkage 2, such as Figure 4 As shown, there are connecting rods A21, B22, and C23 with identical structures. Connecting rods A21 and B22 have completely identical structures and dimensions. The first ends of connecting rods A21 and B22 are connected to the second ends of L-shaped connectors A14 and B15 respectively via revolute joints. The second ends of both are then connected to both ends of connecting rod C23 via revolute joints. The axes of the revolute joints on connecting rods A21, B22, and C23 are all parallel to each other and together with L-shaped connectors A14 and B15, form a parallelogram.

[0042] First gear transmission system 3, such as Figure 6As shown, the assembly includes gear A31, gear C33, bevel gear A34, and bevel gear B35; gear A31 is fixedly connected to the second end of the middle section of the universal joint 13; the side of gear C33 is fixedly connected to the mounting end face of bevel gear A34, and together they are fixedly connected to the rotating shaft C54; bevel gear B35 meshes with bevel gear A34, and its mounting end face is fixedly connected to the rotating shaft of the first rotary drive 6; the first rotary drive 6 drives gear A31 to rotate through bevel gear B35, bevel gear A34, and gear C33;

[0043] Second gear transmission system 4, such as Figure 7 As shown, it includes bevel gear C41 and bevel gear D42; the mounting end face of bevel gear C41 is fixed to the middle section of the connecting rod C23; bevel gear D42 is a hollow structure, meshes with bevel gear C41, and its mounting end face is fixed to the hollow rotating shaft of the second hollow rotary actuator 7.

[0044] In the above scheme, platform A11 and platform B12 are connected by a revolute joint. Platform A11 is connected to a parallelogram branch via L-shaped connectors A14 and B15, while platform B12 is connected to a universal joint 13 via a revolute joint. This connection method decouples the two rotational degrees of freedom of platform A11, allowing them to be driven by the first rotary actuator 6 and the second hollow rotary actuator 7, respectively.

[0045] This invention, through the transmission of gears and symmetrical linkages, not only decouples the two rotational degrees of freedom of the moving platform 1, but also ensures uniform force distribution on the joints and high transmission efficiency, thereby simplifying kinematic calculations and facilitating control. Furthermore, the independent operation of the two branches—the first gear transmission system 3 and the parallel linkage branch 2—allows for a wide range of two-degree-of-freedom rotational movements of the wrist, increasing the rotational range and making the movement posture more flexible. Moreover, the second hollow rotary actuator 7 and the first rotary actuator 6 employ a coaxial nested design, which, combined with the two simple gear transmission systems, significantly reduces the axial and lateral dimensions of the device, resulting in a more compact structure and higher space utilization. This allows for excellent application in limited and narrow joint mounting spaces, while also ensuring high driving capability, bidirectional rotational accuracy, and lightweight design, making it perfectly suited for the narrow joint mounting spaces of prostheses or humanoid robots.

[0046] like Figure 3 As shown, the axes of the revolute joints on platform A11 are perpendicular to each other; the axes of the revolute joints on platform B12 are perpendicular to each other. Figure 8As shown, the top of the platform A11 is used to connect to a prosthetic hand, dexterous hand, or other end effector. The axes of the revolute joints on the universal joint 13 are perpendicular to each other and intersect; the axes of the revolute joints on the L-shaped connector A14 are perpendicular to each other and intersect at a point; the axes of the revolute joints on the L-shaped connector B15 are perpendicular to each other and intersect at a point.

[0047] In the first gear transmission system 3, gear A31 and gear C33 can be directly meshed to achieve transmission. If it is desired to reduce the gear diameter to avoid interference with other structures, it can also be done as follows: Figure 6 As shown, the first gear transmission system 3 also includes gear B32, which meshes with gear A31 and gear C33 respectively; the intermediate connecting plate 51 is also connected to the rotating shaft B53 through a rotating pair, and gear B32 is fixed to the rotating shaft B53.

[0048] In the above scheme, gears A31, B32, and C33 are all cylindrical spur teeth that mesh sequentially. To further avoid interference, the upper part of gear A31 can be removed, forming a half-tooth.

[0049] like Figure 2 As shown, the rotating hole A52, rotating shaft B53 and rotating shaft C54 are arranged at different heights.

[0050] To support the link chain 2 and make the entire assembly more stable, such as Figure 2 As shown, the mounting bracket 5 is also provided with a rotating shaft D55, located below the intermediate connecting plate 51; the frame of the mounting bracket 5 is connected to the rotating shaft D55 through a rotating joint; the middle section of the connecting rod C23 is connected to the rotating shaft D55 through a rotating joint.

[0051] like Figure 2 As shown, the axis of rotating shaft D55 is perpendicular to the axes of rotating hole A52, rotating shaft B53, and rotating shaft C54. The axes of rotating hole A52, rotating shaft B53, and rotating shaft C54 are parallel to each other.

[0052] like Figure 6 As shown, the bevel tooth A34 and the bevel tooth B35 form a bevel tooth fit relationship, and their rotation axes are perpendicular to each other.

[0053] like Figure 7 As shown, the bevel tooth C41 and the bevel tooth D42 form a bevel tooth fit relationship, and the axes of rotation are perpendicular to each other.

[0054] Principle of motion:

[0055] like Figure 6As shown, the rotating shaft of the first rotary actuator 6 drives the bevel gear B35 to rotate in both directions. Through the transmission of bevel gear A34, gear C33, gear B32, and gear A31, the rotational motion is transmitted to the universal joint 13, causing the universal joint 13 to rotate around the rotating hole A52. Driven by the universal joint 13, the platform B12 and platform A11 connected to it also rotate around the rotating hole A52 as a whole.

[0056] like Figure 7 As shown, the second hollow rotary actuator 7 drives the bevel gear D42 to rotate in both directions. Through the transmission of the bevel gear C41, this causes the connecting rod C23 to rotate around the shaft D55. Since the axes of the rotating joints on connecting rods A21, B22, and C23 are parallel to each other, and together with the L-shaped connectors A14 and B15, they form a parallelogram relationship, as shown... Figure 4 As shown, platform A11 will therefore rotate about the axis passing through the center of universal joint 13 and parallel to the axis D55. This rotation direction is perpendicular to the axis of rotating hole A52, which is the direction of motion of the second rotational degree of freedom of platform A11.

[0057] This invention breaks through the traditional constraints on wrist joints regarding "structural compactness," "motion decoupling control," and "large range of motion," designing a two-DOF bionic wrist joint robot with gear and linkage decoupling drive. This scheme achieves decoupling of the two rotational degrees of freedom of the moving platform 1 through gear transmission and linkage transmission, ensuring that the first gear transmission system 3, the second gear transmission system 4, and the linkage branch 2 do not interfere with each other, thereby realizing a large range of two-DOF rotational motion of the wrist. Furthermore, this scheme has a compact structure, high space utilization, and can perfectly adapt to the narrow joint installation space of prostheses or humanoid robots.

[0058] Unless otherwise specified, fixed connections can be riveting, welding, bolting, etc., while movable connections can be hinged, etc.

Claims

1. A two-degree-of-freedom bionic wrist joint robot with decoupled gear and connecting rod drive, characterized in that, include: The mounting bracket (5) has an intermediate connecting plate (51) fixed at the top of its frame; the upper end of the intermediate connecting plate (51) is provided with a rotating hole A (52) and is connected to the rotating shaft C (54) through a rotating pair; The actuator includes a second hollow rotary actuator (7) and a first rotary actuator (6) which are fixed from top to bottom at the middle of the frame of the mounting bracket (5); the rotation shaft of the first rotary actuator (6) passes through the hollow rotation shaft of the second hollow rotary actuator (7); The moving platform (1) includes a U-shaped platform A (11) and a platform B (12), as well as a universal joint (13), an L-shaped connector A (14), and an L-shaped connector B (15); the tops of the platform A (11) and the platform B (12) are connected by a rotating joint; the two ends of the platform A (11) are respectively connected to the first ends of the L-shaped connector A (14) and the L-shaped connector B (15) of the same structure by a coaxial rotating joint; the first end of the middle section of the universal joint (13) is connected to the rotating hole A by a rotating joint, and its two ends are respectively connected to the two ends of the platform B (12) by a coaxial rotating joint; The link chain (2) includes link A (21), link B (22), and link C (23) of the same structure; the first ends of link A (21) and link B (22) are respectively connected to the second ends of L-shaped connector A (14) and L-shaped connector B (15) through rotating joints, and the second ends of both are respectively connected to the two ends of link C (23) through rotating joints; the axes of the rotating joints on link A (21), link B (22) and link C (23) are all parallel to each other, and together with L-shaped connector A (14) and L-shaped connector B (15) form a parallelogram relationship; The first gear transmission system (3) includes gear A (31), gear C (33), bevel gear A (34) and bevel gear B (35); gear A (31) is fixed to the second end of the middle section of the universal joint (13); the side of gear C (33) is fixed to the mounting end face of bevel gear A (34) and together fixed to the rotating shaft C (54); bevel gear B (35) meshes with bevel gear A (34) and its mounting end face is fixed to the rotating shaft of the first rotary driver (6); the first rotary driver (6) drives gear A (31) to rotate through bevel gear B (35), bevel gear A (34) and gear C (33); The second gear transmission system (4) includes bevel gear C (41) and bevel gear D (42); the mounting end face of the bevel gear C (41) is fixed to the middle section of the connecting rod C (23); the bevel gear D (42) is a hollow structure, meshes with the bevel gear C (41), and its mounting end face is fixed to the hollow rotating shaft of the second hollow rotary actuator (7).

2. The two-degree-of-freedom bionic wrist joint robot with decoupled gear and connecting rod drive according to claim 1, characterized in that, The axes of the revolute joints on platform A (11) are perpendicular to each other; the axes of the revolute joints on platform B (12) are perpendicular to each other; the top of platform A (11) is used to connect to the end effector.

3. The two-degree-of-freedom bionic wrist joint robot with decoupled gear and connecting rod drive according to claim 1, characterized in that, The axes of the rotating joints on the universal joint (13) are perpendicular to each other and intersect; the axes of the rotating joints on the L-shaped connector A (14) are perpendicular to each other and intersect at a point; the axes of the rotating joints on the L-shaped connector B (15) are perpendicular to each other and intersect at a point.

4. The two-degree-of-freedom bionic wrist joint robot with decoupled gear and connecting rod drive according to claim 1, characterized in that, The axes of the rotating hole A (52) and the rotating shaft C (54) are parallel.

5. The two-degree-of-freedom bionic wrist joint robot with decoupled gear and connecting rod drive according to claim 4, characterized in that, The first gear transmission system (3) also includes gear B (32), which meshes with gear A (31) and gear C (33) respectively; the intermediate connecting plate (51) is also connected to the rotating shaft B (53) through a rotating pair, and gear B (32) is fixed on the rotating shaft B (53); the axes of the rotating shaft B (53), the rotating hole A (52) and the rotating shaft C (54) are parallel.

6. The two-degree-of-freedom bionic wrist joint robot with decoupled gear and connecting rod drive according to claim 5, characterized in that, Gear A (31), gear B (32), and gear C (33) are all cylindrical spur teeth; gear A (31) is a half tooth.

7. The two-degree-of-freedom bionic wrist joint robot with decoupled gear and connecting rod drive according to claim 4, characterized in that, The mounting bracket (5) is also provided with a rotating shaft D (55); the frame of the mounting bracket (5) is connected to the rotating shaft D (55) through a rotating joint; the middle section of the connecting rod C (23) is connected to the rotating shaft D (55) through a rotating joint; the axis of the rotating shaft D (55) is perpendicular to the axis of the rotating hole A (52) and the axis of the rotating shaft C (54).

8. The two-degree-of-freedom bionic wrist joint robot with decoupled gear and linkage drive according to claim 1, characterized in that, The rotation axes of the bevel tooth A (34) and the bevel tooth B (35) are perpendicular to each other; the rotation axes of the bevel tooth C (41) and the bevel tooth D (42) are perpendicular to each other.

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