Two-degree-of-freedom rotational parallel mechanism, humanoid ankle joint, robot and its skeleton

Abstract

This invention discloses a two-degree-of-freedom rotational parallel mechanism, a humanoid ankle joint, a robot, and its skeleton. The two-degree-of-freedom rotational parallel mechanism includes a fixed platform, a moving platform, a passive constraint branch containing a passive Hooke joint, and two identical RCU motion branches composed of a first revolute joint, a cylindrical joint, and a Hooke joint. The R-joints of the two branches are active inputs, and they satisfy the constraint condition of coincident rotation axes in spatial structure. Thanks to this structure, the proposed parallel mechanism can achieve a large range of end-effector attitude adjustment with a small axial displacement of the cylindrical joint. Power transmission is achieved through a cascaded four-bar linkage, further synthesizing into a novel and compact humanoid ankle joint as per this invention. The parallel mechanism provided by this invention has two rotational degrees of freedom, enabling pitch and roll movements around a fixed rotation center, and can be used in robots, attitude adjustment platforms, and other scenarios.

Description

Technical Field

[0001] This invention specifically relates to a two-degree-of-freedom rotational parallel mechanism, a humanoid ankle joint, a robot and its skeleton, belonging to the field of robotics technology. Background Technology

[0002] In the existing field of two-rotation parallel mechanisms, 3-RPS parallel mechanisms, 2-RPS-S parallel mechanisms (a degenerate of 3-PPS parallel mechanisms), or 2-PPS-PS parallel mechanisms are generally used. These mechanisms have many kinematic pairs, are driven by linear actuator motors, and have relatively weak dynamic performance, making them difficult to meet the requirements of high-dynamic, fast-response equipment. Therefore, using rotary motion as the active input can effectively solve these problems.

[0003] CN103203740A discloses a 2RRU-U two-rotational parallel mechanism, in which the moving platform can only achieve pitch and yaw movements, but not roll movements. CN111515925A discloses a kinematic bifurcation mechanism, whose kinematic bifurcation closed chain also consists of R-joints, C-joints, and U-joints, but the kinematic chain is composed of an URRC topology, with the driving joint being the C-joint. This kinematic chain serves to generate bifurcation movements, making it difficult to achieve structural compactness, and its advantages are not obvious in applications such as humanoid ankle joints. CN104875196A discloses a three-dimensional rotational parallel mechanism, which contains three identical US kinematic branches arranged in a spatially cyclic symmetric manner, exhibiting complex kinematic singularities, and therefore is not suitable as a carrier for realizing miniaturized two-degree-of-freedom devices.

[0004] Existing rotary inputs suffer from rotational symmetry, which reduces structural compactness. To improve compactness and effectively reduce equipment weight, an effective strategy is to use coaxial input for the active motion. This structure facilitates the integrated design of drive components. Therefore, achieving coaxial input for active rotary motion remains one of the pressing issues to be addressed in the industry. Summary of the Invention

[0005] The main objective of this invention is to provide a two-degree-of-freedom rotational parallel mechanism, a humanoid ankle joint, a robot and its skeleton, thereby overcoming the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0007] A first aspect of the present invention provides a two-degree-of-freedom rotational parallel mechanism with coaxial inputs, comprising:

[0008] Fixed platform, moving platform, passive constraint branch, first active motion branch, and second active motion branch.

[0009] The fixed platform is connected to the passive constraint branch and the moving platform respectively, and the moving platform has rotational freedom relative to the fixed platform;

[0010] The first active motion branch and the second active motion branch are spaced apart. The first active motion branch and the second active motion branch are respectively connected to the passive constraint branch and the moving platform. The first active motion branch and the second active motion branch both have rotational degrees of freedom and translational degrees of freedom.

[0011] When at least one of the first active motion branch and the second active motion branch rotates and / or translates, the moving platform is driven to rotate relative to the fixed platform.

[0012] A second aspect of the present invention provides a humanoid ankle joint, comprising: two four-bar linkages and the aforementioned input coaxial two-degree-of-freedom rotational parallel mechanism, one of the two four-bar linkages being connected to the fixed platform and the first active motion chain, and the other being connected to the fixed platform and the second active motion chain, the four-bar linkages being rotatably coupled to the fixed platform, the four-bar linkages having multiple rotational degrees of freedom about a fifth axis, the fifth axis being parallel to the b-axis.

[0013] A third aspect of the present invention provides a robot skeleton, the robot skeleton including the aforementioned humanoid ankle joint.

[0014] A fourth aspect of the present invention provides a robot comprising the aforementioned robot skeleton.

[0015] Compared with the prior art, the advantages of the present invention include:

[0016] The present invention provides a two-degree-of-freedom rotational parallel mechanism with coaxial input that can realize a wide range of pitch and roll motions.

[0017] The present invention provides a two-degree-of-freedom rotational parallel mechanism with coaxial input, comprising a Hooke's joint passive constraint branch and two active motion branches. It has a simple mechanical structure, high load-bearing capacity, and can realize two-degree-of-freedom attitude adjustment of the spatial attitude of a moving platform.

[0018] The present invention provides a two-degree-of-freedom rotational parallel mechanism with coaxial input. The passive constraint branch provides three translational constraints and one rotational constraint, ensuring that the parallel mechanism has two-degree-of-freedom motion function. The first active motion branch and the second active motion branch each provide a spatial constraint and a driving capability, ensuring that the parallel mechanism can realize two-degree-of-freedom rotation.

[0019] The kinematic model of the two-degree-of-freedom rotational parallel mechanism with coaxial input provided by the embodiments of the present invention is simple, has a large workspace, and is easy to control. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of a two-degree-of-freedom rotational parallel mechanism with coaxial inputs, provided in a typical embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the passive constraint branch structure in a typical embodiment of the present invention;

[0022] Figure 3 , Figure 4 This is a schematic diagram of the active motion branch in a typical embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of the overall structure of a two-degree-of-freedom rotational parallel mechanism with coaxial inputs, provided in a typical embodiment of the present invention.

[0024] Figure 6 , Figure 7 , Figure 8 , Figure 9 These are different configuration diagrams of a two-degree-of-freedom rotational parallel mechanism with coaxial input provided in a typical embodiment of the present invention during its motion.

[0025] Figure 10 This is a schematic diagram of a human-like ankle joint formed by assembling a two-degree-of-freedom rotational parallel mechanism with a four-bar linkage and an input coaxial two-degree-of-freedom rotational parallel mechanism in a typical embodiment of the present invention.

[0026] Figure 11 , Figure 12 This is a schematic diagram of a humanoid ankle joint provided in a typical embodiment of the present invention;

[0027] Figure 13 This is a schematic diagram illustrating the mapping relationship between a two-degree-of-freedom rotational parallel mechanism with coaxial input and a humanoid ankle joint, provided in a typical embodiment of the present invention. Detailed Implementation

[0028] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0029] A first aspect of the present invention provides a two-degree-of-freedom rotational parallel mechanism with coaxial inputs, comprising:

[0030] Fixed platform, moving platform, passive constraint branch, first active motion branch, and second active motion branch.

[0031] The fixed platform is connected to the passive constraint branch and the moving platform respectively, and the moving platform has rotational freedom relative to the fixed platform;

[0032] The first active motion branch and the second active motion branch are spaced apart. The first active motion branch and the second active motion branch are respectively connected to the passive constraint branch and the moving platform. The first active motion branch and the second active motion branch both have rotational degrees of freedom and translational degrees of freedom.

[0033] When at least one of the first active motion branch and the second active motion branch rotates and / or translates, the moving platform is driven to rotate relative to the fixed platform.

[0034] Furthermore, the first active motion chain includes a first link, a second link, a first revolute joint, a first cylindrical joint, and a first Hooke's joint. The first link is connected to the passive constraint chain via the first revolute joint, the first link and the second link are connected via the first cylindrical joint, and the second link is connected to the moving platform via the first Hooke's joint. The first revolute joint has a rotational degree of freedom about a first axis, and the first cylindrical joint has a rotational degree of freedom about a second axis and a translational degree of freedom along the second axis.

[0035] The second active motion chain includes a third link, a fourth link, a second revolute joint, a second cylindrical joint, and a second Hooke's joint. The third link is connected to the passive constraint chain via the second revolute joint. The third link and the fourth link are connected via the second cylindrical joint. The fourth link is connected to the moving platform via the second Hooke's joint. The second revolute joint has a rotational degree of freedom about a third axis, and the second cylindrical joint has a rotational degree of freedom about a fourth axis and a translational degree of freedom along the fourth axis. The third axis and the first axis are coaxial.

[0036] Furthermore, the first axis is parallel to the second axis, and the third axis is parallel to the fourth axis.

[0037] Furthermore, the first link and the second link are set at an angle, and the third link and the fourth link are set at an angle.

[0038] Furthermore, the fixed platform and the moving platform are connected via a third Hooke hinge, which has rotational degrees of freedom to rotate about axis a and axis b.

[0039] Furthermore, one of the rotation axes of the first Hooke hinge and the second Hooke hinge is parallel to the a-axis.

[0040] Furthermore, the first Hooke hinge and / or the second Hooke hinge are cross-axis Hooke hinges, and the two rotation axes of the first Hooke hinge and the second Hooke hinge are parallel to the moving platform.

[0041] Furthermore, one of the rotation axes of the first Hooke hinge and the second Hooke hinge is parallel to the a-axis.

[0042] Furthermore, the third Hooke hinge is a cross-axis Hooke hinge, with axis a intersecting axis b perpendicularly, and the two rotation axes of the first and second Hooke hinges are parallel to axis a and axis b, respectively.

[0043] A second aspect of the present invention provides a humanoid ankle joint, comprising: two four-bar linkages and the aforementioned input coaxial two-degree-of-freedom rotational parallel mechanism, one of the two four-bar linkages being connected to the fixed platform and the first active motion chain, and the other being connected to the fixed platform and the second active motion chain, the four-bar linkages being rotatably coupled to the fixed platform, the four-bar linkages having multiple rotational degrees of freedom about a fifth axis, the fifth axis being parallel to the b-axis.

[0044] Furthermore, the four-bar linkage includes multiple revolute joints connected in series, the rotation axis of the revolute joints is parallel to the b-axis, and the revolute joint at the end of the four-bar linkage is connected in series with the first revolute joint / the second revolute joint.

[0045] Furthermore, the revolute joint at the end of the four-bar linkage is integrated with the first revolute joint / second revolute joint.

[0046] In a more specific implementation, the anthropomorphic ankle joint further includes a drive module, which is connected to the four-bar linkage.

[0047] A third aspect of the present invention provides a robot skeleton, the robot skeleton including the aforementioned humanoid ankle joint.

[0048] Furthermore, the robot skeleton is a humanoid robot skeleton.

[0049] A fourth aspect of the present invention provides a robot comprising the aforementioned robot skeleton.

[0050] The following will further explain the technical solution, its implementation process and principle. Unless otherwise specified, the Hooke joint, revolute joint, cylindrical joint, four-bar linkage and other components involved in the embodiments of the present invention are all known in the art and can be obtained by commercial purchase or by processing using processes known in the art.

[0051] In a more typical implementation scheme, please refer to Figure 1 A two-degree-of-freedom rotational parallel mechanism with coaxial input includes a fixed platform 1, a movable platform 2, a passive constraint branch I, a first active motion branch II, and a second active motion branch III. The fixed platform 1 is fixedly connected to the passive constraint branch I and movably connected to the movable platform 2. The movable platform 2 has a rotational degree of freedom relative to the fixed platform 1. The two ends of the first active motion branch II and the second active motion branch III are respectively rotatably connected to the passive constraint branch I and the movable platform 2. The first active motion branch II and the second active motion branch III have rotational degrees of freedom relative to the passive constraint branch I and the movable platform 2. The first active motion branch II and the second active motion branch III themselves have rotational degrees of freedom and translational degrees of freedom to translate along their own rotation axes.

[0052] Please refer to the following for details. Figure 1 , Figure 2 and Figure 5 Both the fixed platform 1 and the moving platform 2 are plate-like structures. The fixed platform 1 includes a support plate 101 and a third Hooke hinge 102. The support plate 101 is rotatably connected to the third Hooke hinge 102, and the support plate 101 is fixedly connected to the passive constraint branch I. The third Hooke hinge 102 is fixedly connected to the moving platform 2. More specifically, the third Hooke hinge 102 is a cross-axis type Hooke hinge. One end of the support plate 101 is rotatably connected to the b-axis of the third Hooke hinge 102, and the other end is fixedly connected to the passive constraint branch I. The a-axis of the third Hooke hinge 102 is rotatably connected to the hinge seat of the third Hooke hinge 102, and the hinge seat of the third Hooke hinge 102 is fixedly connected to the moving platform 2. The moving platform 2 has rotational degrees of freedom to rotate around the a-axis and the b-axis. As a typical implementation, the fixed platform 1 includes two support plates 101, which are spaced apart along the b-axis and connected to both ends of the b-axis. Preferably, the support plates 101 are perpendicular to the moving platform 2.

[0053] Please refer to the following for details. Figure 1 , Figure 3 , Figure 4 and Figure 5The first active motion branch II and the second active motion branch III are axially spaced along the b-axis. The first active motion branch II includes a first connecting rod, a second connecting rod, a first revolute joint (R-joint) 201, a first cylindrical joint (C-joint) 202, and a first Hooke joint (U-joint) 203. The first connecting rod is connected to the passive constraint branch I via the first revolute joint 201. The first connecting rod and the second connecting rod are connected via the first cylindrical joint 202. The second connecting rod is connected to the moving platform 2 via the first Hooke joint 203. The first link and the second link are set at an angle, and the angle between the first link and the second link is an acute angle, but the specific angle is not limited. The first revolute joint 201 has a rotational degree of freedom to rotate about the c-axis (the axis of the c-axis is the aforementioned first axis). The first cylindrical joint 202 has a rotational degree of freedom to rotate about the d-axis (the axis of the d-axis is the aforementioned second axis) and a translational degree of freedom to translate along the d-axis. The first Hooke's joint 203 has rotational degrees of freedom to rotate about the e-axis and the f-axis. During the movement, the b-axis and the f-axis are always parallel.

[0054] More specifically, the first Hooke hinge 203 is a cross-axis Hooke hinge. The first Hooke hinge 203 has a vertically intersecting e-axis and f-axis. The second connecting rod is rotatably connected to the f-axis. The e-axis is rotatably connected to the hinge seat of the first Hooke hinge 203. The hinge seat of the first Hooke hinge 203 is fixedly connected to the moving platform 2.

[0055] Specifically, the second active motion chain III includes a third link, a fourth link, a second revolute joint 301, a second cylindrical joint 302, and a second Hooke hinge 303. The third link is connected to the passive constraint chain I via the second revolute joint 301. The third link and the fourth link are connected via the second cylindrical joint 302. The fourth link is connected to the moving platform 3 via the second Hooke hinge 303. The third link and the fourth link are set at an angle, specifically an acute angle, but the specific angle is not limited. The second revolute joint 301 has a rotational degree of freedom about the third axis, the second cylindrical joint 302 has a rotational degree of freedom about the fourth axis and a translational degree of freedom along the fourth axis, and the second Hooke hinge 303 has a dual-axis rotational degree of freedom. The third axis and the c-axis are coaxial. Specifically, the second Hooke hinge 303 is a cross-shaft type Hooke hinge, the fourth link is rotatably connected to the cross shaft of the second Hooke hinge 303, and the hinge seat of the second Hooke hinge 303 is fixedly connected to the moving platform 2.

[0056] Specifically, the first Hooke hinge 203, the second Hooke hinge 303, and the third Hooke hinge 102 are fixedly arranged on the same surface of the moving platform 2, and the positions of the first Hooke hinge 203, the second Hooke hinge 303, and the third Hooke hinge 102 on the moving platform 2 correspond to the three vertices of a triangle, respectively.

[0057] It should be noted that the first active motion branch II and the second active motion branch III in the embodiments of the present invention have the same structural composition. The structures of the first active motion branch II and the second active motion branch III can be understood together with the entire text. In the embodiments of the present invention, both the first active motion branch II and the second active motion branch III are RCU motion branches composed of a revolute joint (R joint), a cylindrical joint (C joint), and a Hooke joint (U joint). In addition, the revolute joint, cylindrical joint, and Hooke joint involved in the embodiments of the present invention are all known in the art. The cylindrical joint can be composed of a revolute joint and a prismatic joint. Those skilled in the art can understand its structure and working principle without any objection, and will not be explained or described in detail here.

[0058] This invention provides a two-degree-of-freedom rotational parallel mechanism with coaxial input. The rotation axes of the first revolute joint 201 and the second revolute joint 301 of the first active motion branch II and the second active motion branch III are collinear. By driving the first revolute joint 201 and the second revolute joint 301 respectively, changing the angle input of the first revolute joint 201 and the second revolute joint 301, the moving platform 2 can achieve rotation about axis a and about axis b, thereby realizing two-degree-of-freedom rotation of the moving platform 2 in space, and further realizing attitude adjustment of the moving platform 2. The four different attitudes of the moving platform 2 are as follows: Figure 6 , Figure 7 , Figure 8 and Figure 9 As shown. It should be noted that the first revolute joint 201 and the second revolute joint 301 always maintain collinear rotation. This embodiment of the invention provides a two-degree-of-freedom rotational parallel mechanism with coaxial inputs. The passive constraint branch provides three translational constraints and one rotational constraint, ensuring that the parallel mechanism has two-degree-of-freedom motion functionality. The first and second active motion branches each provide a spatial constraint and driving capability, ensuring that the parallel mechanism can achieve two-degree-of-freedom rotation.

[0059] In a typical implementation, the two active motion chains of the two-degree-of-freedom rotational parallel mechanism with coaxial inputs provided in this embodiment of the invention are active inputs. The two chains satisfy the constraint condition of coincidence of rotation axes in spatial structure. Thanks to this structure, the two-degree-of-freedom rotational parallel mechanism can achieve a large range of end-effector attitude adjustment with a small axial displacement of the cylindrical joint. Furthermore, this embodiment of the invention combines the two-degree-of-freedom rotational parallel mechanism with a four-bar linkage and uses the four-bar linkage cascade to achieve power transmission, thereby obtaining a novel and compact anthropomorphic ankle joint.

[0060] Please see Figure 10 , Figure 11 , Figure 12 and Figure 13 A humanoid ankle joint includes two four-bar linkages and a two-degree-of-freedom rotational parallel mechanism with coaxial input. The two four-bar linkages are arranged in parallel between the fixed platform 1 and the first active motion branch II, and the second active motion branch III. One of the four-bar linkages is connected to the fixed platform 1 and the first active motion branch II, while the other is connected to the fixed platform 1 and the second active motion branch III. The four-bar linkages are rotatably engaged with the fixed platform 1. Each four-bar linkage has multiple rotational degrees of freedom about a fifth axis, which is parallel to the b-axis. Each four-bar linkage includes multiple revolute joints connected in series, with multiple rotation axes of each revolute joint parallel to the b-axis. The two four-bar linkages have identical structures and can independently perform rotational movements. Taking one of the four-bar linkages as an example, this four-bar linkage includes a revolute joint A401 connected in series, a revolute joint A401, a revolute joint A402, a revolute joint A403, a revolute joint A404 ... The rotating joints are B402, C403, and D404. Rotating joint A401 is rotatably connected to the fixed platform 1. Rotating joint D404 is connected in series with the first rotating joint 201 / the second rotating joint 301 via connecting rod 3. The rotation axes of rotating joints A401, B402, C403, and D404 are all parallel to the b-axis. As a preferred embodiment, rotating joint D404 is integrated with the first rotating joint 201 / the second rotating joint 301. Connecting rod 3 is the first connecting rod of the first rotating joint 201 / the third connecting rod of the second rotating joint 301. Rotating joint A401 is connected to the drive module (e.g., a rotary drive motor). The drive module drives rotating joint A401 to rotate, thereby driving rotating joints B402, C403, and D404 connected in series with it, as well as the first active motion branch II / the second active motion branch III.

[0061] like Figure 12As shown, the two-degree-of-freedom rotational parallel mechanism with coaxial input provided by this embodiment of the invention can achieve a more compact structure by further optimizing the rod length parameters of each component, while keeping the composition and topology of each active kinematic chain unchanged. At the same time, the two-degree-of-freedom rotational parallel mechanism with coaxial input provided by this embodiment of the invention has two rotational degrees of freedom, which can realize pitch and roll movements around a fixed rotation center, and can be used in scenarios such as robots and attitude adjustment platforms.

[0062] The present invention provides a two-degree-of-freedom rotational parallel mechanism with coaxial input that can realize a wide range of pitch and roll motions.

[0063] The two-degree-of-freedom rotational parallel mechanism with coaxial input provided by this invention includes one Hooke's joint passive constraint branch and two active motion branches. It features a simple mechanical structure and high load-bearing capacity. Furthermore, the kinematic model of this two-degree-of-freedom rotational parallel mechanism with coaxial input is simple, has a large workspace, and is easily controlled.

[0064] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An input coaxial two-degree-of-freedom rotational parallel mechanism, characterized in that, The device comprises a fixed platform (1), a movable platform (2), a passive constraint branch (I), a first active motion branch (II) and a second active motion branch (III), the fixed platform (1) is connected with the passive constraint branch (I) and the movable platform (2) respectively, the movable platform (2) has a rotational freedom degree relative to the fixed platform (1); the passive constraint branch (I) comprises a third hooke joint (102), the fixed platform (1) and the movable platform (2) are connected through the third hooke joint (102), the third hooke joint (102) has a rotational freedom degree of rotating around an a-axis and a b-axis the first active motion branch (II) and the second active motion branch (III) are arranged at intervals, the first active motion branch (II) and the second active motion branch (III) are connected with the passive constraint branch (I) and the movable platform (2) respectively, the first active motion branch (II) and the second active motion branch (III) have a rotational freedom degree and a translational freedom degree; the first active motion branch (II) comprises a first connecting rod, a second connecting rod and a first rotational pair (201), a first cylindrical pair (202) and a first hooke joint (203), the first connecting rod is connected with the passive constraint branch (I) through the first rotational pair (201), the first connecting rod and the second connecting rod are connected through the first cylindrical pair (202), the second connecting rod is connected with the movable platform (2) through the first hooke joint (203); the first rotational pair (201) has a rotational freedom degree of rotating around a first axis, the first cylindrical pair (202) has a rotational freedom degree of rotating around a second axis and a translational freedom degree of translating along the second axis; the second active motion branch (III) comprises a third connecting rod, a fourth connecting rod and a second rotational pair (301), a second cylindrical pair (302) and a second hooke joint (303), the third connecting rod is connected with the passive constraint branch (I) through the second rotational pair (301), the third connecting rod and the fourth connecting rod are connected through the second cylindrical pair (302), the fourth connecting rod is connected with the movable platform (2) through the second hooke joint (303); the second rotational pair (301) has a rotational freedom degree of rotating around a third axis, the second cylindrical pair (302) has a rotational freedom degree of rotating around a fourth axis and a translational freedom degree of translating along the fourth axis, wherein the third axis and the first axis are coaxial; when at least one of the first active motion branch (II) and the second active motion branch (III) rotates and / or translates, the movable platform (2) is driven to rotate relative to the fixed platform (1). The first axis is parallel to the second axis, and the third axis is parallel to the fourth axis.

2. The input coaxial two-degree-of-freedom rotational parallel mechanism according to claim 1, characterized in that: The first connecting rod and the second connecting rod are arranged at an angle, and the third connecting rod and the fourth connecting rod are arranged at an angle.

3. The input coaxial two-degree-of-freedom rotational parallel mechanism according to claim 2, characterized in that: One of the rotational axes of the first hooke joint and the second hooke joint is parallel to the a-axis.

4. The input coaxial two-degree-of-freedom rotational parallel mechanism according to claim 1, characterized in that: ​ 5. The input coaxial two-degree-of-freedom rotational parallel mechanism according to claim 2, characterized in that: The first and / or second Hooke joint is a cross axle type Hooke joint, and two rotation axes of the first and second Hooke joint are parallel to the moving platform (2).

6. The input coaxial two-degree-of-freedom rotational parallel mechanism according to claim 1, characterized in that: The third Hooke joint is a cross axle type Hooke joint, the a axis and the b axis are perpendicular to each other, and two rotation axes of the first and second Hooke joint are parallel to the a axis and the b axis respectively.

7. A humanoid ankle joint, characterized by The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10.

8. The anthropomorphic ankle joint of claim 7, wherein: The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10.

9. The anthropomorphic ankle joint of claim 8, wherein: The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10.

10. The anthropomorphic ankle joint of claim 7, wherein: The robot skeleton is a humanoid robot skeleton.

11. A robotic skeleton, characterized by: The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10.

12. The robotic skeleton of claim 11, wherein: The robot skeleton is a humanoid robot skeleton.

13. A robot, characterized in that The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton is a humanoid robot skeleton. The robot skeleton comprises the human-like ankle joint according to any one of claims 7-10. The robot skeleton

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