A wrist joint, a robot arm and a humanoid robot

Abstract

The utility model discloses a wrist joint, mechanical arm and humanoid robot belong to humanoid robot technical field. Wrist joint includes joint module, first mounting seat, second mounting seat, support axle, bearing and support seat. The fixed end and output of joint module are connected first, second mounting seat respectively. Support axle passes through second mounting seat, and bearing is located therebetween, and support seat is fixed in first mounting seat and supports support axle. Support axle, bearing and support seat constitute radial auxiliary support to second mounting seat. When second mounting seat bears bending moment, the bending moment can be passed to first mounting seat through auxiliary support, thereby greatly reducing the bending moment of joint module output end. The utility model discloses simple structure can effectively improve the rigidity of wrist joint, load capacity and the reliability of drive module.

Description

Technical Field

[0001] This utility model belongs to the field of humanoid robot technology, and relates to a wrist joint structure, as well as a robotic arm and a humanoid robot including the wrist joint. Background Technology

[0002] The wrist joint of a humanoid robot is a core load-bearing and moving component connecting the forearm and hand. It must simultaneously meet core requirements such as flexible movement with three degrees of freedom, heavy load-bearing capacity, compact structure, and convenient maintenance. Its structural design directly determines the robot's operational stability and service life. Existing humanoid robot wrist joints mainly adopt configurations such as three rotating modules in series, four-bar linkage, or "one rotating module + two linear modules." Among these, wrist structures using rotating modules are basically single-end supported.

[0003] CN118357959A discloses a linkage parallel wrist joint, which is driven in parallel by two symmetrically arranged transmission chains (including seven components such as the wrist active lever arm, upper arm linkage, and lower arm linkage), with the wrist drive motor located at the upper arm end to reduce motion inertia. However, its core drawback is that the connection between the transmission chain and the wrist side swing component and wrist pitch component is a single-sided hinge support without additional auxiliary support structure. When the wrist is subjected to radial load, the hinge point and the reducer must share the entire bending moment, which can easily lead to linkage deformation and universal joint wear after long-term use. In addition, the transmission chain contains multiple hinge points and detachable parts, and the linkage length and joint clearance must be calibrated one by one during assembly, resulting in a long total assembly time. Maintenance requires complete disassembly, which seriously affects work efficiency. At the same time, the parallel linkage structure is complex, and the processing and assembly costs are high.

[0004] CN120921437A discloses a mechanical wrist joint, robotic arm, robot, control method, and control device, employing a "driver + drive rope" transmission method. Dual-mode motion is achieved through two drivers rotating in opposite / same directions. The drivers are positioned at the end of the arm frame, away from the wrist, to reduce end-effector inertia. However, this solution has two major drawbacks: first, the rope transmission lacks stiffness, easily leading to slack over long-term use and decreased wrist joint motion accuracy; second, the shaft assembly only provides single-sided rotational support through end plates, lacking double-sided auxiliary support structures. When the wrist is subjected to impact loads, the bending moment is concentrated at the connection between the shaft and the reducer, easily causing the shaft to bend and deform; furthermore, the fit between the rope and the pulley requires extremely high installation precision, necessitating repeated adjustments to the rope tension during assembly, making maintenance difficult.

[0005] CN220051902U discloses a wrist joint, robotic arm, and robot, employing a "cross-axis + four-bar linkage" structure. Two drive components in parallel drive a connecting component to swing around a dual-axis, resulting in a compact structure and good biomimetic effect. However, its core drawback lies in the following: the first axis of the cross-axis only achieves single-end engagement through two support parts, and the second axis is hinged to the connecting component on one side without a double-sided support structure. When the wrist performs pitching or lateral movements, the reducer must directly bear part of the bending moment, which can easily lead to fatigue damage of the harmonic reducer's flexure under long-term heavy loads. Furthermore, the frame, connecting component, and support parts are designed as multiple separate parts, requiring calibration of the coaxiality of the cross-axis and connecting rods during assembly. This necessitates the use of specialized positioning fixtures, resulting in long assembly times and the need to disassemble multiple bolts during maintenance, leading to poor convenience.

[0006] In summary, existing wrist joint solutions generally employ a single-sided support structure, which has significant drawbacks: when the end effector is subjected to lateral force or bending moment, this bending moment will act directly and completely on the output end of the drive module and be transmitted to its internal precision reducer (such as a harmonic reducer). The reducer, especially its flexible wheel, is sensitive to bending moment; prolonged or excessive bending moment will significantly reduce the reducer's lifespan and accuracy, and may even lead to damage.

[0007] Therefore, how to effectively distribute the bending moment borne by the wrist joint end in terms of structure and reduce the burden on the drive module has become a technical problem that needs to be solved. Summary of the Invention

[0008] The present invention aims to provide a wrist joint, a robotic arm, and a humanoid robot to solve the problem that existing wrist joint drive modules are susceptible to bending moment damage due to unilateral support.

[0009] To achieve the above objectives, the first aspect of this utility model provides a wrist joint, comprising: a joint module having a fixed end and an output end; a first mounting base connected to the fixed end of the joint module; a second mounting base connected to the output end of the joint module; a support shaft passing through the second mounting base; at least one bearing sleeved on the support shaft; and a support seat connected to the outer ring of the bearing and fixed to the first mounting base. The support shaft, the bearing, and the support seat constitute radial auxiliary support for the second mounting base.

[0010] In the above technical solution, the joint module is responsible for driving, and its two ends are connected to the first and second mounting seats respectively. The key to this utility model lies in the addition of an auxiliary support structure composed of a support shaft, bearings, and a support seat. This structure establishes a parallel force transmission path between the second mounting seat and the stable first mounting seat. When the second mounting seat is subjected to radial load or bending moment, the load can be directly transmitted to the first mounting seat through this auxiliary support structure, thereby significantly diverting the bending moment acting on the output end of the joint module and protecting the transmission components inside the module.

[0011] Preferably, there are at least two bearings arranged axially spaced along the support shaft. This dual-bearing arrangement provides more stable support and effectively resists bending moments in different directions.

[0012] Furthermore, both ends of the support shaft are fixed to the support base. This fixing method makes the support structure more robust.

[0013] In one specific implementation, the first mounting base is a wrist-side motion mounting base, the second mounting base is a wrist flexion motion mounting base, and the two are connected by the joint module to achieve pitch movement, while the auxiliary support is used to enhance the bending resistance of this motion joint.

[0014] Furthermore, the wrist joint also includes a radial rotation motion mounting base on which a drive module is mounted. The output end of the drive module is connected to the wrist-side motion mounting base, thereby realizing the rotational freedom of the wrist.

[0015] Preferably, the joint module includes a motor and a reducer, wherein the reducer may be a harmonic reducer sensitive to bending moment. The structure of this invention can effectively protect such precision reducers.

[0016] A second aspect of this utility model provides a robotic arm, which includes a lever and a wrist joint as described above, wherein a first mounting seat of the wrist joint is mounted on the end of the lever.

[0017] The third aspect of this utility model provides a humanoid robot, which includes a torso and a robotic arm as described above, wherein the robotic arm is connected to the torso via a shoulder joint.

[0018] Compared with existing technologies, this utility model has the following beneficial technical effects: By setting a simple auxiliary support structure, the end bending moment is cleverly diverted, significantly reducing the harmful bending moment borne by the drive module, thereby improving the overall stiffness and load capacity of the wrist joint, as well as the service life and reliability of the drive module (especially the reducer). The structure is simple and compact, and easy to assemble and maintain. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the wrist joint in one embodiment of the present invention.

[0020] Figure 2 for Figure 1 The diagram shows a cross-sectional view of the wrist joint during wrist flexion.

[0021] Reference numerals: 1- Joint module, 2- Radial rotation motion mounting seat, 3- Forearm, 4- Drive plate, 5- First mounting seat, 6- Support shaft, 7- Bearing, 8- Support seat, 9- Second mounting seat, 10- Hand mounting flange. Detailed Implementation

[0022] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the protection scope of this utility model.

[0023] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance, quantity, or position.

[0024] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances. Example 1

[0025] like Figure 1As shown, this embodiment provides a wrist joint. The wrist joint mainly includes a radial rotation motion mounting base 2 for achieving rotational freedom, a joint module 1 for achieving pitch freedom, a forearm 3, a drive plate 4, a first mounting base 5, a support shaft 6, a bearing 7, a support seat 8, a second mounting base 9, and a hand mounting flange 10. Another drive module (not fully shown in the figure) can be mounted on the radial rotation motion mounting base 2. The output end of this module is connected to the first mounting base 5 (i.e., the wrist-side motion mounting base), driving it to rotate around the rotation axis.

[0026] The key improvement of this invention lies in the pitch joint. The first mounting base 5 is connected to the housing (fixed end) of the joint module 1. The output end of the joint module 1 is fixedly connected to the second mounting base 9 (i.e., the wrist flexion mounting base). Therefore, the joint module 1 can drive the second mounting base 9 to rotate around its output axis (pitch axis). The hand mounting flange 10 is fixed to the second mounting base 9 for mounting end effectors such as dexterous hands.

[0027] Combination Figure 2 As can be seen from the cross-sectional view, the core of this utility model lies in the setting of a radial auxiliary support structure, in which the support shaft 6, bearings 7, and support seat 8 together form the second support of the joint. Specifically, a support shaft 6 passes through a through hole opened on the second mounting seat 9. Two bearings 7 (deep groove ball bearings are used as an example in this embodiment) are installed between the support shaft 6 and the inner wall of the through hole of the second mounting seat 9. The two bearings 7 are arranged at intervals along the axial direction of the support shaft 6. The inner ring of the bearing 7 is interference-fitted with the support shaft 6 or fixed by other means, and the outer ring is interference-fitted with the inner wall of the through hole of the second mounting seat 9. A support seat 8 (a block-shaped part with mounting holes machined in this embodiment) is firmly fixed to the first mounting seat 5 by multiple screws. The two ends of the support shaft 6 are fixed to the support seat 8 by set screws or end pressure plates. Thus, the support shaft 6, bearings 7, and support seat 8 together constitute a rigid radial auxiliary support connecting the second mounting seat 9 and the first mounting seat 5.

[0028] Working Principle: In the traditional structure, the second mounting base 9 is supported only at a single point by the output end of the joint module 1. When the load on the hand mounting flange 10 generates the bending moment M shown in the figure, this bending moment is entirely borne by the output end of the joint module 1. In this invention, due to the addition of auxiliary support, when the bending moment M is applied, the second mounting base 9 and the support shaft 6 generate an interaction force through the bearing 7. This force is transmitted through the support shaft 6 to the support base 8, and finally to the first mounting base 5, which serves as the foundation. In this way, most of the bending moment is "unloaded" onto the auxiliary support path, and the output end of the joint module 1 mainly bears the driving torque, greatly reducing the bending moment it experiences. This effectively protects the precision components such as the reducer inside the joint module 1 and improves the lateral stiffness of the joint. Example 2

[0029] A robotic arm including the wrist joint. This embodiment provides a robotic arm including a lever and a wrist joint as described in Embodiment 1.

[0030] like Figure 1 As shown, the arm (forearm 3) has a hollow structure, inside which is installed a drive plate 4 and other necessary cables and sensors (not all are shown in the figure). The drive plate 4 is electrically connected to the joint module 1 of the wrist joint and the drive module on the radial rotation motion mounting base 2 via cables, and is used to power them and transmit control signals.

[0031] The wrist joint is mounted to the end of the forearm 3 via bolts or other fasteners through the base portion of its first mounting seat 5 (wrist-side motion mounting seat). This constitutes a robotic arm with a high-rigidity, high-reliability wrist. Due to the adoption of the double-sided support structure of Embodiment 1, the wrist joint of this robotic arm exhibits stronger resistance to bending deformation, more stable positioning accuracy, and a longer lifespan for the drive module when performing tasks such as grasping heavy objects, withstanding lateral impacts, or performing precision assembly. Example 3

[0032] A humanoid robot including the robotic arm. This embodiment provides a humanoid robot comprising a torso and a robotic arm as described in Embodiment 2.

[0033] The proximal end of the robotic arm (i.e., the end of the forearm 3 without the wrist joint) is connected to the humanoid robot's torso via a shoulder joint (the connection between the shoulder joint and the torso is a conventional technique and is not shown in detail in the figure). The shoulder joint is a multi-degree-of-freedom joint used to enable multi-directional movement of the robotic arm relative to the torso.

[0034] Because the robotic arm's wrist joint employs a structure with radial auxiliary support, the load-bearing capacity and operational stability of the end effector (such as a dexterous hand) are significantly improved when the humanoid robot uses its arm to perform tasks. Whether carrying materials, manipulating tools, or interacting with people or the environment, its wrist can more effectively resist external disturbance torques, improving the success rate and safety of task execution, while reducing the risk of failure due to joint module overload.

[0035] Although embodiments of the present invention have been shown and described above, it is understood that these embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and alterations to the above embodiments within the scope of the present invention without departing from its principles and spirit. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A wrist joint, characterized in that, include: The joint module has a fixed end and an output end; The first mounting base is connected to the fixed end of the joint module; The second mounting base is connected to the output end of the joint module; A support shaft passes through the second mounting base; At least one bearing is sleeved on the support shaft; and A support base is connected to the outer ring of the bearing and fixed to the first mounting base; The support shaft, the bearing, and the support seat constitute radial auxiliary support for the second mounting base.

2. The wrist joint according to claim 1, characterized in that, The bearings are at least two, and the at least two bearings are arranged at an axial distance along the support shaft.

3. The wrist joint according to claim 1, characterized in that, Both ends of the support shaft are fixed to the support base.

4. The wrist joint according to claim 1, characterized in that, The first mounting base is a wrist-side movement mounting base, and the second mounting base is a wrist-flexion movement mounting base.

5. The wrist joint according to claim 4, characterized in that, It also includes a radial rotation motion mounting base, on which a drive module is mounted, and the output end of the drive module is connected to the wrist-side motion mounting base.

6. The wrist joint according to claim 1, characterized in that, The joint module includes a motor and a reducer connected to the output end of the motor.

7. The wrist joint according to claim 6, characterized in that, The speed reducer is a harmonic speed reducer.

8. A robotic arm, characterized in that, It includes a lever and a wrist joint as described in any one of claims 1 to 7, wherein the first mounting base of the wrist joint is mounted on the end of the lever.

9. The robotic arm according to claim 8, characterized in that, A drive plate is provided inside the arm, and the drive plate is electrically connected to the joint module of the wrist joint.

10. A humanoid robot, characterized in that, It includes a torso and a robotic arm as described in claim 8 or 9, the robotic arm being connected to the torso via a shoulder joint.

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