Mechanical arm

Abstract

The utility model relates to the technical field of mechanical arms, in particular to a mechanical arm which comprises a mounting base, a first arm, a second arm and a tail end executing assembly, a transmission box is rotationally connected to the mounting base, a driving mechanism is arranged in the transmission box, the first arm is rotationally connected with the transmission box, and the second arm is rotationally connected with the first arm. The tail end execution assembly is movably connected with the second arm, a transmission connecting rod assembly is arranged between the first arm and the second arm, one end of the transmission connecting rod assembly penetrates through the first arm and then is connected with the driving mechanism, the other end of the transmission connecting rod assembly penetrates through the second arm and then is connected with the tail end execution assembly, and the driving mechanism is used for driving the transmission box to horizontally rotate relative to the mounting base. The first arm is driven to rotate up and down relative to the transmission case, the second arm is driven to rotate up and down relative to the first arm, the tail end execution assembly is driven to move relative to the second arm, and the mechanical arm is lighter, small in size and better in overall rigidity.

Description

Technical Field

[0001] The utility model relates to the technical field of robotic arms, and particularly relates to a robotic arm. Background Art

[0002] The use of robotic arms is becoming more and more popular. At present, industrial robotic arms on the market are widely used in many fields such as manufacturing, assembly, and handling. However, the existing robotic arms still have certain limitations in terms of operation accuracy, flexibility, and adaptability. The joint design of some robotic arms is not flexible enough, resulting in limited operation ability in narrow spaces. For example, in the utility model patent with the publication number CN221818698U named 'A Robotic Arm', it cannot perform planar rotation according to the design, and the operating degrees of freedom are limited; the utility model patent with the publication number CN221640894U named 'A Robotic Arm' has a single function, can only use a suction cup to clamp, uses belt drive, and has low positioning accuracy. Currently, most robotic arms adopt a multi-arm segment design, and each arm segment is equipped with a driving motor, which increases the self-weight of the execution mechanism and the volume of the robotic arm. The processing accuracy requirements for parts are high, and the cost is expensive. Content of the Utility Model

[0003] In order to solve the above technical problems, the embodiment of the utility model provides a robotic arm, which adds a reduction mechanism to reduce the volume of the motor and the weight of each arm segment, increases the torque output, makes the overall structure smaller in volume and lighter in weight. An interface for the end effector assembly is reserved at the front end, which is more convenient for replacing the end effector assembly. The purpose is to make each arm segment of the robotic arm more flexible and lighter.

[0004] The utility model is realized through the following technical solutions:

[0005] A robotic arm includes a mounting base, a first arm, a second arm, and an end effector assembly. A transmission box is rotatably connected to the mounting base, and a driving mechanism is arranged inside the transmission box. The first arm is rotatably connected to the transmission box, the second arm is rotatably connected to the first arm, and the end effector assembly is movably connected to the second arm. A transmission link assembly is arranged between the first arm and the second arm. One end of the transmission link assembly passes through the first arm and is connected to the driving mechanism, and the other end of the transmission link assembly passes through the second arm and is connected to the end effector assembly. The driving mechanism is used to drive the transmission box to rotate horizontally relative to the mounting base, drive the first arm to rotate up and down relative to the transmission box, drive the second arm to rotate up and down relative to the first arm, and drive the end effector assembly to move relative to the second arm.

[0006] Further preferably, the transmission link assembly includes a first link structure, a second link structure, a triangular link structure, and a third link structure. The triangular link structure is at the connection between the first arm and the second arm. Inside the top end of the first arm, there is a connecting shaft five, and a third connecting piece is sleeved on the connecting shaft five. One end of the second link structure is rotatably connected to the driving mechanism, and the other end of the second link structure is rotatably connected to the third connecting piece. The three ends of the triangular link are respectively rotatably connected to the connecting shaft five, the third link structure, and the first link structure. The other end of the first link structure is rotatably connected to the driving mechanism, and the other end of the third link structure is movably connected to the end effector.

[0007] Further preferably, the driving mechanism includes a second driving component. A third pulley is provided at the output end of the second driving component. Inside the transmission box, there is a connecting shaft one that is rotatably connected. At one end of the connecting shaft one, there is a fourth pulley. The third pulley is in transmission connection with the fourth pulley. At the other end of the connecting shaft one, there is a fifth pulley. The fifth pulley is in transmission connection with the first arm and the transmission link assembly.

[0008] Further preferably, the driving mechanism further includes a third driving component. A sixth pulley is provided at the output end of the third driving component. Inside the transmission box, there is a connecting shaft two that is rotatably connected. At one end of the connecting shaft two, there is a seventh pulley. The sixth pulley is in transmission connection with the seventh pulley. At the other end of the connecting shaft two, there is an eighth pulley. The eighth pulley is in transmission connection with the first arm and the transmission link assembly.

[0009] Further preferably, the driving mechanism further includes a first driving component. A first pulley is provided at the output end of the first driving component. On the mounting base, there is a support shaft that penetrates into the transmission box. At the bottom inside the transmission box, there is a base shaft. The base shaft is horizontally rotatably connected to the support shaft. A second pulley is sleeved on the top end of the base shaft. The second pulley is in transmission connection with the first pulley.

[0010] Further preferably, a first support frame and a second support frame are provided at the top of the transmission box. A third connecting shaft is rotatably provided on the first support frame, and a fourth connecting shaft is rotatably provided on the second support frame. The two sides of the first arm are respectively rotatably connected to the third connecting shaft and the fourth connecting shaft.

[0011] Further preferably, a ninth pulley is sleeved on one end of the third connecting shaft, and a first connecting piece is sleeved on the other end of the third connecting shaft. On one side of the bottom end of the first arm, there is a first structural member. The first connecting piece is connected to the first structural member. One end of the first connecting piece is connected to the first link structure. The fifth pulley is in transmission connection with the ninth pulley.

[0012] Further preferably, a tenth pulley is sleeved on one end of the fourth connecting shaft, and a transmission member is sleeved on the other end of the fourth connecting shaft. The transmission member is rotatably connected to the second link structure. The eighth pulley is in transmission connection with the tenth pulley. [[ID=)19]]

[0013] The beneficial effects of the present utility model:

[0014] A robotic arm of the present utility model solves the technical problems of the existing robotic arms being inflexible and large in size. In this robotic arm, the driving mechanism is refitted inside the transmission box, which reduces the weights of the first arm and the second arm, making the first arm and the second arm lighter, smaller in size and more convenient to move. In addition to being able to bear tensile force, the transmission link assembly can also bear pressure, improving the rigidity between the first arm and the second arm, and thus making the overall rigidity of the robotic arm better.

[0015] The following further elaborates on the specific embodiments of the present utility model with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings are used to provide a further understanding of the present utility model and form a part of the specification. Together with the following specific embodiments, they are used to explain the present utility model, but do not constitute a limitation to the present utility model. In the drawings:

[0017] Figure 1 is a schematic structural view of a robotic arm of the present utility model.

[0018] Figure 2 is a schematic internal structural view of a robotic arm of the present utility model.

[0019] Figure 3 is of the present utility model Figure 2 magnified view of part A.

[0020] Figure 4 is a cross-sectional view of the mounting base and the transmission box of a robotic arm of the present utility model.

[0021] Figure 5 is a schematic top view structure of a transmission box of a robotic arm of the present utility model.

[0022] Figure 6 is a schematic structure view of the transmission box and the first arm of a robotic arm of the present utility model.

[0023] Figure 7 is a schematic structure view of the first arm of a robotic arm of the present utility model.

[0024] Figure 8 is a schematic structure view of the connection between the first arm and the second arm of a robotic arm of the present utility model.

[0025] Figure 9 is a schematic three-dimensional structure view of a robotic arm of the present utility model.

[0026] 1 - Installation base, 2 - Transmission box, 3 - First support frame, 4 - Second support frame, 5 - Third connecting shaft, 6 - Fourth connecting shaft, 7 - Ninth pulley, 8 - First connecting piece, 9 - Tenth pulley, 10 - Second connecting piece, 11 - Transmission part, 12 - Support shaft, 20 - First drive assembly, 21 - First pulley, 22 - Base shaft, 23 - Second pulley, 30 - Second drive assembly, 31 - Third pulley, 32 - First connecting shaft, 33 - Fourth pulley, 34 - Fifth pulley, 40 - Third drive assembly, 41 - Sixth pulley, 42 - Second connecting shaft, 43 - Seventh pulley, 44 - Eighth pulley, 50 - Transmission link assembly, 51 - First link structure, 52 - Second link structure, 53 - Third link structure, 54 - Triangular link structure, 55 - Fifth connecting shaft, 56 - Third connecting piece, 60 - First arm, 61 - First structural part, 62 - Second structural part, 63 - First limiting structure, 64 - Second limiting structure, 70 - Second arm, 71 - Third limiting structure, 72 - Fourth limiting structure, 80 - End effector assembly. Detailed implementation mode

[0027] The following details the implementation mode of the present utility model. The examples of the implementation mode are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The implementation mode described below by referring to the drawings is exemplary and is only used to explain the present utility model and cannot be understood as a limitation to the present utility model.

[0028] Referring to Figures 1-9 , the robotic arm of the present utility model includes an installation base 1, a transmission box 2, a first arm 60, a second arm 70, an end effector assembly 80, and a transmission link assembly 50. The installation base 1 is fixed on the working platform and serves as the support foundation for the entire robotic arm. The transmission box 2 contains a drive mechanism, a reducer, and other transmission components for transmitting the power of the motor to each joint. The transmission box 2 is horizontally rotatably connected to the installation base 1 to facilitate the horizontal rotation of the robotic arm. The bottom end of the first arm 60 is rotatably connected to the transmission box 2. The second arm 70 is rotatably connected to the top end of the first arm 60. The end effector assembly 80 is movably arranged at the end of the second arm 70. The transmission link assembly 50 is at the rotational connection between the first arm 60 and the second arm 70, and one end of the transmission link assembly 50 passes through the first arm 60 and is connected to the drive mechanism in the transmission box 2, and the other end of the transmission link assembly 50 passes through the second arm 70 and is connected to the end effector assembly 80. Thus, the drive mechanism in the transmission box 2 can drive the second arm 70 to rotate relative to the first arm 60 through the transmission link assembly 50; and the drive mechanism in the transmission box 2 can drive the end effector assembly 80 to move relative to the second arm 70 by driving the transmission link assembly 50.

[0029] The transmission link assembly 50 includes a link structure one 51, a link structure two 52, a triangular link structure 54, and a link structure three 53. The link structure one 51 and the link structure two 52 are within the first arm 60. In this embodiment, one side of the first arm 60 and the second arm 70 is open. Therefore, the first arm 60 is provided with a limit structure one 63 and a limit structure two 64. The limit structure one 63 and the limit structure two 64 limit the movement range of the link structure one 51 and the link structure two 52 within the first arm 60. The link structure three 53 is within the second arm 70. The second arm 70 is provided with a limit structure three 71 and a limit structure four 72. The limit structure three and the limit structure four limit the movement range of the link structure three 53 within the second arm 70. The triangular link structure 54 is at the connection of the first arm 60 and the second arm 70. Inside the top of the first arm 60, there is a connecting shaft five 55. A connecting piece three 56 is sleeved on the connecting shaft five 55. One end of the link structure two 52 is rotatably connected to a transmission part 11 of a driving mechanism on the transmission box 2. The other end of the link structure two 52 is rotatably connected to the connecting piece three 56. The three ends of the triangular link structure 54 are respectively rotatably connected to the connecting shaft five 55, the link structure three 53, and the link structure one 51. The other end of the link structure one 51 is rotatably connected to the driving mechanism. The other end of the link structure three 53 is rotatably connected to a connecting component of the end effector assembly 80. Preferably, the other end of the link structure three 53 is a shaft, which is convenient for installing the end effector. The driving mechanism within the transmission box 2 can drive the first arm 60. The first arm 60 drives the link structure two 52 to move. The link structure two 52 drives the triangular link structure 54 to rotate around the connecting shaft five 55, thereby driving the second arm 70 to rotate relative to the first arm 60. The link structure one 51 and the triangular link structure 54 drive one end of the link structure three 53 to rotate around the connecting shaft five 55, and the other end of the link structure three 53 rotates around the end effector assembly 80, thereby driving the end effector assembly 80 to move relative to the second arm 70.

[0030] The setting of the transmission link assembly 50 enables the driving mechanism within the transmission box 2 to be installed on the mounting base 1, reducing the self-weight of the first arm 60 and the second arm 70. The connecting shafts between the link structure two 52 and the link structure three 53, as well as between them and the first arm 60 and the second arm 70, are connected using the triangular link structure 54, improving the structural stability and movement flexibility. At the same time, the driving mechanism within the transmission box 2 is connected to the first arm 60 and the second arm 70 respectively through the transmission link assembly 50. The transmission link assembly 50 can bear both tensile and compressive forces, making the connection between the first arm 60 and the second arm 70 a rigid connection, improving the connection rigidity between the first arm 60 and the second arm 70, and further improving the overall rigidity of the robotic arm.

[0031] The drive mechanism in the transmission case 2 includes a first drive assembly 20, a second drive assembly 30, and a third drive assembly 40. The first drive assembly 20, the second drive assembly 30, and the third drive assembly 40 are all mainly composed of a control board, a stepping motor, and a harmonic reducer. A first pulley 21 is provided at the output end of the first drive assembly 20. There is a bracket in the transmission case 2 for mounting the first drive assembly 20 and the first pulley 21. A support shaft 12 penetrating into the transmission case 2 is provided on the mounting base 1. A base shaft 22 is provided at the bottom inside the transmission case 2. The base shaft 22 is horizontally rotatably connected to the support shaft 12. The transmission case 2 is rotatably connected to the mounting base 11 through the base shaft 22. A second pulley 23 is sleeved on the top end of the base shaft 22. The second pulley 23 and the first pulley 21 are connected by a synchronous belt. The first drive assembly 20 drives the second pulley 23 and the first pulley 21 to rotate, and then the second pulley 23 drives the base shaft 22 and the transmission case 2 to rotate, so that the first drive assembly 20 drives the transmission case 2 to perform a rotational motion in the horizontal direction.

[0032] A third pulley 31 is provided at the output end of the second drive assembly 30. There is a bracket in the transmission case 2 for mounting the second drive assembly 30 and the third pulley 31. A first connecting shaft 32 is provided inside the transmission case 2. The first connecting shaft 32 is rotatably mounted on this bracket. A fourth pulley 33 is provided at one end of the first connecting shaft 32. The third pulley 31 and the fourth pulley 33 are connected by a synchronous belt. A fifth pulley 34 is provided at the other end of the first connecting shaft 32. The fifth pulley 34 is in transmission connection with the first arm 60 and the transmission link assembly 50. The second drive assembly 30 drives the first connecting shaft 32 to rotate, thereby driving the first arm 60 to rotate.

[0033] The second drive assembly 30 and the third drive assembly 40 have similar structures and are symmetrically arranged. A sixth pulley 41 is provided at the output end of the third drive assembly 40. There is a bracket in the transmission case 2 for mounting the third drive assembly 40 and the sixth pulley 41. A second connecting shaft 42 is provided inside the transmission case 2. The second connecting shaft 42 is rotatably mounted on this bracket. A seventh pulley 43 is provided at one end of the second connecting shaft 42. The sixth pulley 41 and the seventh pulley 43 are connected by a synchronous belt. A eighth pulley 44 is provided at the other end of the second connecting shaft 42. The eighth pulley 44 is in transmission connection with the first arm 60. The second drive assembly 30 drives the second connecting shaft 42 to rotate.

[0034] On the top end of the transmission case 2, there are a first support frame 3 and a second support frame 4. A third connecting shaft 5 is rotatably arranged on the first support frame 3, and a fourth connecting shaft 6 is rotatably arranged on the second support frame 4. Both sides of the first arm 60 are respectively rotatably connected to the third connecting shaft 5 and the fourth connecting shaft 6. Thus, the first arm 60 is rotatably connected to the transmission case 2. A ninth pulley 7 is sleeved on one end of the third connecting shaft 5, and a first connecting piece 8 is sleeved on the other end of the third connecting shaft 5. On one side of the bottom end of the first arm 60, there is a first structural member 61. The first connecting piece 8 is connected to the first structural member 61 of the first arm 60. One end of the first connecting piece 8 is connected to the first connecting rod structure 51 of the transmission connecting rod assembly 50. The fifth pulley 34 and the ninth pulley 7 are connected by a synchronous belt. The fifth pulley 34 drives the ninth pulley 7 to rotate, and the ninth pulley 7 drives the first arm 60 to rotate.

[0035] A tenth pulley 9 is sleeved on one end of the fourth connecting shaft 6, and a second connecting piece 10 is sleeved in the middle of the fourth connecting shaft 6. On the other side of the bottom end of the first arm 60, there is a second structural member 62. The second connecting piece 10 is connected to the second structural member 62 of the first arm 60. A transmission member 11 is sleeved on the other end of the fourth connecting shaft 6. The transmission member 11 is rotatably connected to the second connecting rod structure 52 of the transmission connecting rod assembly 50. The eighth pulley 44 and the tenth pulley 9 are connected by a synchronous belt. The third driving component 40 drives the eighth pulley 44 to rotate, and the eighth pulley 44 drives the tenth pulley 9 to rotate. The transmission member 11 is fixedly connected to the fourth connecting shaft 6. The transmission member 11 drives the second connecting rod structure 52 of the transmission connecting rod assembly 50 to rotate, thereby driving the triangular connecting rod structure 54 to rotate relative to the fifth connecting shaft 55, and further driving the second arm 70 to rotate relative to the first arm 60.

[0036] Working principle: The stepping motor in the second driving component 30 drives the third pulley 31 to rotate. The third pulley 31 and the fourth pulley 33 are in transmission, driving the fifth pulley 34 on the first connecting shaft 32 to rotate. The fifth pulley 34 and the ninth pulley 7 are in transmission. The ninth pulley 7 drives the first structural member 61 and the first connecting piece 8 on the third connecting shaft 5 to rotate. The first structural member 61 drives the first arm 60 to rotate relative to the transmission case 2. The first connecting piece 8 drives the first connecting rod structure 51 to rotate. The first connecting rod structure 51 and the second connecting rod structure 52 jointly act on the triangular connecting rod to drive the third connecting rod structure 53 to rotate. The third connecting rod structure 53 drives the end effector assembly 80 to move relative to the second arm 70. The stepping motor in the third driving component 40 drives the sixth pulley 41 to rotate. The sixth pulley 41 and the seventh pulley 43 are in transmission. The seventh pulley 43 drives the eighth pulley 44 on the second connecting shaft 42 to rotate. The eighth pulley 44 and the tenth pulley 9 are in transmission. The tenth pulley 9 drives the transmission member 11 on the fourth connecting shaft 6 to rotate. The transmission member 11 drives the second connecting rod structure 52 to rotate, thereby driving the triangular connecting rod structure 54 to rotate relative to the fifth connecting shaft 55, and further driving the second arm 70 to rotate relative to the first arm 60. The stepping motor in the first driving component 20 drives the first pulley 21 to rotate. The first pulley 21 and the second pulley 23 are in transmission. The second pulley 23 drives the base shaft 22 and the transmission case 2 to rotate, thereby driving the transmission case 2 to perform a horizontal rotation movement on the mounting base 1.

[0037] The utility model provides a robotic arm with a small volume and better flexibility. Through the driving component one 20, the driving component two 30, and the driving component three 40 in the driving mechanism, as well as multiple connecting shafts, belt pulleys, and the transmission link assembly 50, the transmission box 2 is rotated horizontally relative to the mounting base 1, the first arm 60 rotates up and down relative to the transmission box 2, the second arm 70 rotates up and down relative to the first arm 60, and the end effector assembly 80 moves relative to the second arm 70, realizing the flexible operation of the robotic arm. At the same time, the driving mechanism is modified and installed in the transmission box 2, reducing the weights of the first arm 60 and the second arm 70, making the first arm 60 and the second arm 70 lighter, with a small volume and convenient movement. The transmission link assembly 50 can not only bear tensile force but also bear compressive force, improving the rigidity between the first arm 60 and the second arm 70, thus making the overall rigidity of the robotic arm better. The end effector assembly 80 can be replaced at any time according to actual needs, such as grippers, small slides, small air pump devices, suction cups, etc.

[0038] In summary, although the present utility model has been disclosed above with preferred embodiments, the above preferred embodiments are not intended to limit the present utility model. Those of ordinary skill in the art can make various changes and modifications without departing from the spirit and scope of the present utility model. Therefore, the protection scope of the present utility model shall be subject to the scope defined by the claims.

Claims

1. A robotic arm, characterized in that: It includes an installation base (1), a first arm (60), a second arm (70) and an end effector assembly (80). A transmission box (2) is rotatably connected to the installation base (1). A driving mechanism is provided inside the transmission box (2). The first arm (60) is rotatably connected to the transmission box (2). The second arm (70) is rotatably connected to the first arm (60). The end effector assembly (80) is movably connected to the second arm (70). A transmission link assembly (50) is provided between the first arm (60) and the second arm (70). One end of the transmission link assembly (50) passes through the first arm (60) and is connected to the driving mechanism. The other end of the transmission link assembly (50) passes through the second arm (70) and is connected to the end effector assembly (80). The driving mechanism is used to drive the transmission box (2) to rotate horizontally relative to the installation base (1), drive the first arm (60) to rotate up and down relative to the transmission box (2), drive the second arm (70) to rotate up and down relative to the first arm (60), and drive the end effector assembly (80) to move relative to the second arm (70).

2. The robotic arm according to claim 1, characterized in that: The transmission link assembly (50) includes a first link structure (51), a second link structure (52), a triangular link structure (54) and a third link structure (53). The triangular link structure (54) is at the connection of the first arm (60) and the second arm (70). A fifth connecting shaft (55) is provided inside the top end of the first arm (60). A third connecting piece (56) is sleeved on the fifth connecting shaft (55). One end of the second link structure (52) is rotatably connected to the driving mechanism. The other end of the second link structure (52) is rotatably connected to the third connecting piece (56). The three ends of the triangular link structure (54) are respectively rotatably connected to the fifth connecting shaft (55), the third link structure (53) and the first link structure (51). The other end of the first link structure (51) is rotatably connected to the driving mechanism. The other end of the third link structure (53) is movably connected to the end effector assembly (80).

3. The robotic arm according to claim 2, characterized in that: The driving mechanism includes a second driving component (30). A third pulley (31) is provided at the output end of the second driving component (30). A first connecting shaft (32) is rotatably connected inside the transmission box (2). A fourth pulley (33) is provided at one end of the first connecting shaft (32). The third pulley (31) is in transmission connection with the fourth pulley (33). A fifth pulley (34) is provided at the other end of the first connecting shaft (32). The fifth pulley (34) is in transmission connection with the first arm (60) and the transmission link assembly (50).

4. A robotic arm according to claim 3, characterized in that: The drive mechanism further includes a third drive assembly (40). A sixth pulley (41) is provided at the output end of the third drive assembly (40). A second connecting shaft (42) that is rotationally connected is provided inside the transmission case (2). A seventh pulley (43) is provided at one end of the second connecting shaft (42). The sixth pulley (41) is in transmission connection with the seventh pulley (43). An eighth pulley (44) is provided at the other end of the second connecting shaft (42). The eighth pulley (44) is in transmission connection with the first arm (60) and the transmission link assembly (50).

5. A robotic arm according to claim 1, characterized in that: The drive mechanism further includes a first drive assembly (20). A first pulley (21) is provided at the output end of the first drive assembly (20). A support shaft (12) that penetrates into the transmission case (2) is provided on the mounting base (1). A base shaft (22) is provided at the inner bottom of the transmission case (2). The base shaft (22) is horizontally rotationally connected to the support shaft (12). A second pulley (23) is sleeved on the top end of the base shaft (22). The second pulley (23) is in transmission connection with the first pulley (21).

6. A robotic arm according to claim 4, characterized in that: A first support frame (3) and a second support frame (4) are provided at the top end of the transmission case (2). A third connecting shaft (5) is rotatably provided on the first support frame (3). A fourth connecting shaft (6) is rotatably provided on the second support frame (4). Two sides of the first arm (60) are respectively rotationally connected to the third connecting shaft (5) and the fourth connecting shaft (6).

7. A robotic arm according to claim 6, wherein: A ninth pulley (7) is sleeved on one end of the third connecting shaft (5). A first connecting member (8) is sleeved on the other end of the third connecting shaft (5). A first structural member (61) is provided on one side of the bottom end of the first arm (60). The first connecting member (8) is connected to the first structural member (61). One end of the first connecting member (8) is connected to the first link structure (51). The fifth pulley (34) is in transmission connection with the ninth pulley (7).

8. A robotic arm according to claim 6, characterized in that: A tenth pulley (9) is sleeved on one end of the fourth connecting shaft (6). A transmission member (11) is sleeved on the other end of the fourth connecting shaft (6). The transmission member (11) is rotationally connected to the second link structure (52). The eighth pulley (44) is in transmission connection with the tenth pulley (9).

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