Scissor fork type four-degree-of-freedom parallel mechanism

Abstract

The application provides a scissors-fork type four-degree-of-freedom parallel mechanism, which comprises a fixed platform, a movable platform, a first supporting chain and a second supporting chain, both ends of the first supporting chain and the second supporting chain are connected with the fixed platform and the movable platform respectively, and the fixed platform, the first supporting chain, the movable platform and the second supporting chain are connected to form a closed loop structure, the first supporting chain and the second supporting chain are symmetrically distributed on the left and right sides of the movable platform, and the first supporting chain is the same as the second supporting chain, the mechanism can realize the four-degree-of-freedom movement of the movable platform in three degrees of freedom translation and rotation around a vertical axis, has simple movement, large rigidity and large workspace, and can be applied to high-speed and high-precision movement scenes such as industrial automation assembly, material picking, packaging and sorting.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of parallel robots, in particular to a scissor fork type four-degree-of-freedom parallel mechanism. BACKGROUND

[0002] The scissor fork mechanism, also known as the parallelogram lifting mechanism, is a mechanical device widely used in different fields. Its main feature is to achieve vertical lifting motion through the linkage structure of the parallelogram. The design of this mechanism is based on the parallelogram principle in geometry, which uses a series of mutually parallel support rods to maintain the horizontal stability of the platform during extension and retraction. Due to the symmetrical structure and parallelogram characteristics of the scissor fork mechanism, it can maintain the balance of the load when the load changes, avoid the tilting of the platform, and occupy less space in the retracted state, allowing for a larger lifting height in a limited space.

[0003] Among various parallel robots, four-degree-of-freedom parallel robots with three translational and one rotational (3T1R) can efficiently sort and assemble various types of materials and parts with different distribution directions. Existing 3T1R parallel mechanisms, such as the Delta improved mechanism, achieve rotation through additional intermediate branches, making it difficult to achieve smooth and precise motion. Double moving platform configuration mechanisms, such as H4, I4, Heli4, and Par4, have complex kinematics due to the large number of moving components. Single moving platform configuration mechanisms, such as 4-RRPaR and 4-URU, have relatively simple configurations, but have limited translational workspace, small rotational angle, and poor isotropic velocity transmission characteristics. Chinese patent CN215660246U proposes a four-degree-of-freedom parallel robot based on a biased parallelogram mechanism, which can achieve three translational degrees of freedom of the moving platform and rotation around the vertical direction through four linear input motions. Its structure is simple, the workspace is large, and it is suitable for high-speed and high-precision sorting occasions. In order to make the structure compact, a symmetrical biased parallelogram mechanism is used to transmit linear input motion, but this structure causes the vertical velocity to weaken after the linear input motion is transmitted to the moving platform, limiting the vertical workspace of the mechanism. SUMMARY

[0004] The technical problem to be solved by the present application is that the existing four-degree-of-freedom parallel robot, due to the structure, causes the vertical velocity to weaken after the linear input motion is transmitted to the moving platform, resulting in limited vertical workspace of the mechanism. To overcome the above defects of the prior art, the present application provides a scissor fork type four-degree-of-freedom parallel mechanism.

[0005] The application provides a scissors fork type four-degree-of-freedom parallel mechanism, which comprises a fixed platform, a movable platform, a first supporting chain and a second supporting chain, both ends of the first supporting chain and the second supporting chain are connected with the fixed platform and the movable platform respectively, and the fixed platform, the first supporting chain, the movable platform and the second supporting chain are connected to form a closed loop structure, and the first supporting chain and the second supporting chain are symmetrically distributed on the left and right sides of the movable platform.

[0006] The first supporting chain comprises a first active driving mechanism, a first double-layer scissors fork amplification mechanism, a first connecting piece, a first parallelogram linkage mechanism and a second connecting piece, the first active driving mechanism is installed on the fixed platform, the first active driving mechanism is hinged with an input end of the first double-layer scissors fork amplification mechanism, an output end of the first double-layer scissors fork amplification mechanism is hinged with the first connecting piece, so as to move the first connecting piece along the front-back or up-down translation, one end of the first parallelogram linkage mechanism is hinged with the first connecting piece, the other end of the first parallelogram linkage mechanism is hinged with the second connecting piece, and the second connecting piece is rotationally connected on the movable platform.

[0007] The second supporting chain comprises a second active driving mechanism, a second double-layer scissors fork amplification mechanism, a third connecting piece, a second parallelogram linkage mechanism and a fourth connecting piece, the second active driving mechanism is installed on the fixed platform, the second active driving mechanism is hinged with an input end of the second double-layer scissors fork amplification mechanism, an output end of the second double-layer scissors fork amplification mechanism is hinged with the third connecting piece, so as to move the third connecting piece along the front-back or up-down translation, one end of the second parallelogram linkage mechanism is hinged with the third connecting piece, the other end of the second parallelogram linkage mechanism is hinged with the fourth connecting piece, and the fourth connecting piece is rotationally connected on the movable platform.

[0008] The second connecting piece and the fourth connecting piece are arranged in a left-right interval, when the rotation direction of the second connecting piece is opposite to that of the fourth connecting piece, the movable platform rotates around a vertical shaft.

[0009] Compared with the prior art, the scissors fork type four-degree-of-freedom parallel mechanism has the following advantages: through the amplification of the first double-layer scissors fork amplification mechanism and the second double-layer scissors fork amplification mechanism in the first supporting chain and the second supporting chain, the front-back movement of the first active driving mechanism and the second active driving mechanism is converted into the up-down translation of the first connecting piece and the third connecting piece, so as to drive the movable platform to move in the vertical direction, since the working space of the movable platform in the vertical direction depends on the lifting height of the first double-layer scissors fork amplification mechanism and the second double-layer scissors fork amplification mechanism, the speed is not weakened after the amplification of the amplification mechanism, and the working space of the movable platform in the vertical direction becomes larger.

[0010] In a possible implementation, the fixed platform comprises a base, a first guide rail and a second guide rail, the first guide rail and the second guide rail are respectively arranged on the left and right sides of the base, the movable platform is located between the first guide rail and the second guide rail, and the first guide rail and the second guide rail are arranged to extend in the front-rear direction.

[0011] Compared with the prior art, the above technical solution can freely increase the length of the first guide rail and the second guide rail extending in the front-rear direction according to requirements, thereby being applicable to a larger space.

[0012] In a possible implementation, the first driving mechanism comprises a first sliding block and a second sliding block, the first sliding block and the second sliding block are both slidingly connected to the first guide rail, and the first sliding block and the second sliding block can move towards each other, in the same direction or in opposite directions on the first guide rail; the second driving mechanism comprises a third sliding block and a fourth sliding block, the third sliding block and the fourth sliding block are both slidingly connected to the second guide rail, and the third sliding block and the fourth sliding block can move towards each other, in the same direction or in opposite directions on the second guide rail.

[0013] Compared with the prior art, the above technical solution can realize the relative independence of the movement of each sliding block, so that the mechanism can freely realize complex actions.

[0014] In a possible implementation, the first double-layer scissor fork amplification mechanism comprises two first connecting rods, two second connecting rods, two third connecting rods and two fourth connecting rods, the two first connecting rods are arranged in parallel and spaced apart, the two second connecting rods are arranged in parallel and spaced apart, the two third connecting rods are arranged in parallel and spaced apart, and the two fourth connecting rods are arranged in parallel and spaced apart.

[0015] The lower end of the first connecting rod is hingedly connected to the first sliding block, the upper end of the first connecting rod is hingedly connected to the lower end of the third connecting rod, the upper end of the third connecting rod is hingedly connected to the first connecting piece, the lower end of the second connecting rod is hingedly connected to the second sliding block, the upper end of the second connecting rod is hingedly connected to the lower end of the fourth connecting rod, and the upper end of the fourth connecting rod is hingedly connected to the first connecting piece.

[0016] The first connecting rod and the second connecting rod are arranged in cross and are hingedly connected to each other through a first pin shaft, and the third connecting rod and the fourth connecting rod are hingedly connected to the first connecting piece through a second pin shaft.

[0017] Compared with the prior art, the above technical solution can amplify the transmission of vertical movement through the first double-layer scissor fork amplification mechanism, thereby increasing the working space of the movable platform in the vertical direction.

[0018] In a possible implementation, the second double-layered scissor mechanism is arranged in the same structure as the first double-layered scissor mechanism.

[0019] Compared with the prior art, the above technical solution can ensure that the structure is more compact and the transmission and amplification of movement are more stable through the structure synchronization of the second double-layered scissor mechanism and the first double-layered scissor mechanism.

[0020] In a possible implementation, when the first slider, the second slider, the third slider, and the fourth slider move synchronously in the same direction, the moving platform moves horizontally in the front-back direction.

[0021] When the first slider and the second slider, the third slider and the fourth slider move synchronously in the same direction, the moving platform moves horizontally in the front-back direction.

[0022] When the first slider and the second slider move synchronously in the same direction, the third slider and the fourth slider move synchronously in the opposite direction, the moving platform moves horizontally to the right, and vice versa, the moving platform moves horizontally to the left.

[0023] When the first slider and the second slider move synchronously in the same direction, the third slider and the fourth slider move synchronously in the opposite direction, the moving platform rotates around the vertical axis.

[0024] Compared with the prior art, the above technical solution can realize the movement of the mechanism in four degrees of freedom, i.e., left-right, front-back, up-down, and rotation, and the movement direction is diversified, which is more free and flexible, and is suitable for more complex and variable fields such as industrial automation assembly, material picking, and packaging sorting.

[0025] In a possible implementation, the first parallelogram linkage mechanism includes two connecting rods, the two connecting rods are arranged in parallel and spaced apart, one end of the connecting rod is hinged to the first connecting piece, and the other end of the connecting rod is hinged to the third connecting piece.

[0026] Compared with the prior art, the above technical solution can increase the working space while ensuring the stability of the mechanism through the parallel and spaced arrangement of the two connecting rods of the first parallelogram linkage mechanism, and has the characteristics of large working space, simple movement, and large rigidity.

[0027] In a possible implementation, the second parallelogram linkage mechanism is arranged in the same structure as the first parallelogram linkage mechanism.

[0028] Compared with the prior art, the above technical solution can ensure that the structure is more compact and the transmission and amplification of movement are more stable through the structure synchronization of the second double-layered scissor mechanism and the first double-layered scissor mechanism. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Structure diagram of the scissor fork type four-degree-of-freedom parallel mechanism of the present application;

[0030] Figure 2 Structure diagram of the first double-layer scissor fork amplification mechanism of the present application;

[0031] Figure 3 Diagram of the moving platform of the scissor fork type four-degree-of-freedom parallel mechanism of the present application moving along the left-right direction;

[0032] Figure 4 Diagram of the moving platform of the scissor fork type four-degree-of-freedom parallel mechanism of the present application moving along the up-down direction;

[0033] Figure 5 Diagram of the moving platform of the scissor fork type four-degree-of-freedom parallel mechanism of the present application rotating around the vertical axis.

[0034] Explanation of reference numerals:

[0035] 1, fixed platform; 11, base; 12, first guide rail; 13, second guide rail; 2, moving platform; 3, first branch chain; 31, first active driving mechanism; 311, first sliding block; 312, second sliding block; 32, first double-layer scissor fork amplification mechanism; 321, first connecting rod; 322, second connecting rod; 323, third connecting rod; 324, fourth connecting rod; 325, first pin shaft; 326, second pin shaft; 33, first connecting piece; 34, first parallelogram linkage mechanism; 341, connecting rod; 35, second connecting piece; 4, second branch chain; 41, second active driving mechanism; 411, third sliding block; 412, fourth sliding block; 42, second double-layer scissor fork amplification mechanism; 43, third connecting piece; 44, second parallelogram linkage mechanism; 45, fourth connecting piece. DETAILED DESCRIPTION

[0036] First, those skilled in the art should understand that these embodiments are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can adjust them as needed in order to adapt to specific application occasions.

[0037] In the description of the embodiments of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0038] In the embodiments of the present application, unless specifically stated and limited otherwise, a first feature is "on", "above", or "over" a second feature can mean that the first and second features are in direct contact, or the first and second features are in indirect contact with an intermediate medium. Moreover, the first feature "above", "over", and "on" the second feature can mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. The first feature "below", "under", and "underneath" the second feature can mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is horizontally lower than the second feature.

[0039] The present application will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0040] Reference is made to Figures 1 to 5The embodiment of the application discloses a scissors fork type four-degree-of-freedom parallel mechanism. Specifically, the mechanism comprises a fixed platform 1, a movable platform 2, a first branch chain 3 and a second branch chain 4. The two ends of the first branch chain 3 and the second branch chain 4 are connected with the fixed platform 1 and the movable platform 2 respectively, and the fixed platform 1, the first branch chain 3, the movable platform 2 and the second branch chain 4 form a closed loop structure. The first branch chain 3 and the second branch chain 4 are symmetrically distributed on the left and right sides of the movable platform 2. The first branch chain 3 comprises a first driving mechanism 31, a first double-layer scissors fork amplification mechanism 32, a first connecting piece 33, a first parallelogram linkage mechanism 34 and a second connecting piece 35. The first driving mechanism 31 is installed on the fixed platform 1. The first driving mechanism 31 is hingedly connected with the input end of the first double-layer scissors fork amplification mechanism 32. The output end of the first double-layer scissors fork amplification mechanism 32 is hingedly connected with the first connecting piece 33, so as to move the first connecting piece 33 along the front-back or up-down direction. One end of the first parallelogram linkage mechanism 34 is hingedly connected with the first connecting piece 33. The other end of the first parallelogram linkage mechanism 34 is hingedly connected with the second connecting piece 35. The second connecting piece 35 is horizontally rotatably connected on the movable platform 2. The second branch chain 4 comprises a second driving mechanism 41, a second double-layer scissors fork amplification mechanism 42, a third connecting piece 43, a second parallelogram linkage mechanism 44 and a fourth connecting piece 45. The second driving mechanism 41 is installed on the fixed platform 1. The second driving mechanism 41 is hingedly connected with the input end of the second double-layer scissors fork amplification mechanism 42. The output end of the second double-layer scissors fork amplification mechanism 42 is hingedly connected with the third connecting piece 43, so as to move the third connecting piece 43 along the front-back or up-down direction. One end of the second parallelogram linkage mechanism 44 is hingedly connected with the third connecting piece 43. The other end of the second parallelogram linkage mechanism 44 is hingedly connected with the fourth connecting piece 45. The fourth connecting piece 45 is horizontally rotatably connected on the movable platform 2. The second connecting piece 35 and the fourth connecting piece 45 are arranged at intervals on the left and right sides. When the rotation direction of the second connecting piece 35 is opposite to that of the fourth connecting piece 45, the movable platform 2 rotates around a vertical shaft.

[0041] Specifically, in order to meet the requirements, the mechanism can operate in a larger space. The fixed platform 1 comprises a base 11, a first guide rail 12 and a second guide rail 13. The first guide rail 12 and the second guide rail 13 are arranged at intervals on the left and right sides of the base 11. The movable platform 2 is located between the first guide rail 12 and the second guide rail 13. The first guide rail 12 and the second guide rail 13 are arranged to extend in the front-back direction. The length of the first guide rail 12 and the second guide rail 13 extending in the front-back direction can be freely increased.

[0042] Specifically, in order to make the mechanism freely realize complex actions, the first active driving mechanism 31 includes a first slider 311 and a second slider 312, both of which are slidingly connected to the first guide rail 12, and the first slider 311 and the second slider 312 can move towards each other, in the same direction or away from each other on the first guide rail 12; the second active driving mechanism 41 includes a third slider 411 and a fourth slider 412, both of which are slidingly connected to the second guide rail 13, and the third slider 411 and the fourth slider 412 can move towards each other, in the same direction or away from each other on the second guide rail 13, so as to realize the relative independence of the movement of each slider.

[0043] Specifically, in order to strengthen the transmission of vertical movement and increase the working space of the moving platform 2 in the vertical direction, the first double-layer scissor amplifier mechanism 32 includes two first connecting rods 321, two second connecting rods 322, two third connecting rods 323 and two fourth connecting rods 324, the two first connecting rods 321 are spaced apart and arranged in parallel, the two second connecting rods 322 are spaced apart and arranged in parallel, the two third connecting rods 323 are spaced apart and arranged in parallel, and the two fourth connecting rods 324 are spaced apart and arranged in parallel; the lower end of the first connecting rod 321 is hinged to the first slider 311, the upper end of the first connecting rod 321 is hinged to the lower end of the third connecting rod 323, the upper end of the third connecting rod 323 is hinged to the first connecting piece 33, the lower end of the second connecting rod 322 is hinged to the second slider 312, the upper end of the second connecting rod 322 is hinged to the lower end of the fourth connecting rod 324, and the upper end of the fourth connecting rod 324 is hinged to the first connecting piece 33; the first connecting rod 321 and the second connecting rod 322 are cross-connected and hinged to each other by a first pin shaft 325, and the third connecting rod 323 and the fourth connecting rod 324 are hinged to the first connecting piece 33 by a second pin shaft 326.

[0044] Specifically, in order to make the mechanism structure more compact and the transmission of vertical movement more stable, the second double-layer scissor amplifier mechanism 42 is arranged in the same structure as the first double-layer scissor amplifier mechanism 32.

[0045] Specifically, to make the moving platform 2 of the mechanism realize more free and flexible movement in four degrees of freedom of left and right, front and back, up and down, and rotation, when the first slider 311, the second slider 312, the third slider 411 and the fourth slider 412 move synchronously and in the same direction, the moving platform 2 moves in the front-back direction; when the first slider 311 and the second slider 312 and the third slider 411 and the fourth slider 412 move synchronously and in the same direction, the moving platform 2 moves in the up-down direction; when the first slider 311 and the second slider 312 move synchronously and in the opposite direction, and the third slider 411 and the fourth slider 412 move synchronously and in the same direction, the moving platform 2 moves to the right, and vice versa, the moving platform 2 moves to the left; when the first slider 311 and the second slider 312 move synchronously and in the same direction, and the third slider 411 and the fourth slider 412 move synchronously and in the opposite direction, the moving platform 2 rotates around the vertical axis.

[0046] As can be known from the above, the working principle of the scissor-type four-degree-of-freedom parallel mechanism is that the first slider 311 and the second slider 312 slide in the first guide rail 12 in the front-back direction, and the third slider 411 and the fourth slider 412 slide in the second guide rail 13 in the front-back direction, respectively, and drive the first connecting rod 321 and the second connecting rod 322 to move in the same direction or in the opposite direction or not to move when sliding, the lower end of the third connecting rod 323 is hingedly connected to the upper end of the first connecting rod 321 through the first pin shaft 325, and the lower end of the fourth connecting rod 324 is hingedly connected to the second connecting rod 322 through the second pin shaft 326, thereby realizing the first double-layer scissor-type amplification mechanism 32 and the second double-layer scissor-type amplification mechanism 42, which are lifted in a scissor-type manner, thereby driving the first connecting member 33 and the third connecting member 43 to move in the front-back or up-down direction, when moving up and down, the first connecting member 33 and the third connecting member 43 drive the first parallelogram linkage mechanism 34 and the first parallelogram linkage mechanism 34 to move to the left or to the right or in the opposite direction, when moving in the opposite direction, the second connecting member 35 and the fourth connecting member 45, which are respectively hingedly connected to the first connecting member 33 and the third connecting member 43, move vertically upward and downward, thereby driving the moving platform 2 to lift, since the vertical working space of the moving platform 2 depends on the lifting height of the first double-layer scissor-type amplification mechanism 32 and the second double-layer scissor-type amplification mechanism 42, the speed is not weakened after amplification by the amplification mechanism, and the vertical working space of the moving platform 2 becomes larger.

[0047] The linear input motion of the four sliders in combination can realize the motion of the moving platform 2 in four degrees of freedom, i.e., three degrees of freedom of translation and one degree of rotation around a vertical axis. Specifically, when the first slider 311, the second slider 312, the third slider 411 and the fourth slider 412 move synchronously and in the same direction, the moving platform 2 moves in the front-rear direction; when the first slider 311 and the second slider 312 and the third slider 411 and the fourth slider 412 move synchronously and in opposite directions, the moving platform 2 moves in the vertical direction; when the first slider 311 and the second slider 312 move synchronously and in opposite directions and the third slider 411 and the fourth slider 412 move synchronously and in the same direction, the moving platform 2 moves in the left direction; when the first slider 311 and the second slider 312 move synchronously and in the same direction and the third slider 411 and the fourth slider 412 move synchronously and in opposite directions, the moving platform 2 rotates around the vertical axis. The amplification of the first double-layer scissor fork amplification mechanism 32 and the second double-layer scissor fork amplification mechanism 42 also greatly increases the working space of the machine, making it more efficient and more suitable for more complex and variable fields such as industrial automation assembly, material picking and packaging sorting.

[0048] In the embodiment, the first parallelogram linkage mechanism 34 includes two connecting rods 341, which are spaced apart and parallel to each other, one end of the connecting rod 341 being hinged to the first connecting piece 33, and the other end of the connecting rod 341 being hinged to the third connecting piece 43.

[0049] Specifically, to make the structure of the second parallelogram linkage mechanism 44 synchronous with that of the first parallelogram linkage mechanism 34, so as to ensure that the structure is more compact and the motion transmission is more stable, the second parallelogram linkage mechanism 44 is arranged in the same structure as the first parallelogram linkage mechanism 34.

[0050] Thus, by arranging the two connecting rods 341 of the first parallelogram linkage mechanism 34 and the second parallelogram linkage mechanism 44 in parallel and spaced apart, the working space is increased while the stability of the mechanism is ensured, and the mechanism has the characteristics of large working space, simple motion and large rigidity.

[0051] In the description of the embodiments of the present application, it should be noted that in the description of the present application, the terms indicating the direction or position relationship are based on the direction or position relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or member must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0052] In the description of the application, the description of the terms "one embodiment", "some embodiments", "in this embodiment", "specific example", or "some examples" and the like means that the specific features, mechanisms, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In the description, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0053] The above description is merely a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A scissor-fork four-degree-of-freedom parallel mechanism, characterized in that, The device comprises a fixed platform (1), a movable platform (2), a first branch chain (3) and a second branch chain (4), the two ends of the first branch chain (3) and the second branch chain (4) are connected with the fixed platform (1) and the movable platform (2) respectively, and the fixed platform (1), the first branch chain (3), the movable platform (2) and the second branch chain (4) are connected to form a closed loop structure, and the first branch chain (3) and the second branch chain (4) are symmetrically distributed on the left and right sides of the movable platform (2). The first branch chain (3) comprises a first driving mechanism (31), a first double-layered scissor fork amplification mechanism (32), a first connecting piece (33), a first parallelogram linkage mechanism (34) and a second connecting piece (35), the first driving mechanism (31) is installed on the fixed platform (1), the first driving mechanism (31) is hingedly connected with the input end of the first double-layered scissor fork amplification mechanism (32), the output end of the first double-layered scissor fork amplification mechanism (32) is hingedly connected with the first connecting piece (33), so as to move the first connecting piece (33) along the front-back or up-down direction, one end of the first parallelogram linkage mechanism (34) is hingedly connected with the first connecting piece (33), the other end of the first parallelogram linkage mechanism (34) is hingedly connected with the second connecting piece (35), and the second connecting piece (35) is rotatably connected to the movable platform (2). The second branch chain (4) comprises a second driving mechanism (41), a second double-layered scissor fork amplification mechanism (42), a third connecting piece (43), a second parallelogram linkage mechanism (44) and a fourth connecting piece (45), the second driving mechanism (41) is installed on the fixed platform (1), the second driving mechanism (41) is hingedly connected with the input end of the second double-layered scissor fork amplification mechanism (42), the output end of the second double-layered scissor fork amplification mechanism (42) is hingedly connected with the third connecting piece (43), so as to move the third connecting piece (43) along the front-back or up-down direction, one end of the second parallelogram linkage mechanism (44) is hingedly connected with the third connecting piece (43), the other end of the second parallelogram linkage mechanism (44) is hingedly connected with the fourth connecting piece (45), and the fourth connecting piece (45) is rotatably connected to the movable platform (2). The second connecting piece (35) and the fourth connecting piece (45) are arranged on the left and right sides, when the rotation direction of the second connecting piece (35) is opposite to that of the fourth connecting piece (45), the movable platform (2) rotates around the vertical shaft.

2. The scissor-fork four-degree-of-freedom parallel mechanism according to claim 1, characterized in that, The fixed platform (1) comprises a base (11), a first guide rail (12) and a second guide rail (13), the first guide rail (12) and the second guide rail (13) are arranged on the left and right sides of the base (11) respectively, the movable platform (2) is located between the first guide rail (12) and the second guide rail (13), and the first guide rail (12) and the second guide rail (13) extend along the front-back direction.

3. The scissor-fork four-degree-of-freedom parallel mechanism according to claim 2, characterized in that, The first driving mechanism (31) comprises a first slider (311) and a second slider (312), both of which are slidingly connected to the first guide rail (12), and the first slider (311) and the second slider (312) can move towards each other, in the same direction or in the opposite direction on the first guide rail (12); the second driving mechanism (41) comprises a third slider (411) and a fourth slider (412), both of which are slidingly connected to the second guide rail (13), and the third slider (411) and the fourth slider (412) can move towards each other, in the same direction or in the opposite direction on the second guide rail (13).

4. The scissor-fork four-degree-of-freedom parallel mechanism according to claim 3, characterized in that, The first double-layer scissor mechanism (32) comprises two first connecting rods (321), two second connecting rods (322), two third connecting rods (323) and two fourth connecting rods (324), the two first connecting rods (321) are arranged in parallel and spaced apart, the two second connecting rods (322) are arranged in parallel and spaced apart, the two third connecting rods (323) are arranged in parallel and spaced apart, and the two fourth connecting rods (324) are arranged in parallel and spaced apart. The lower end of the first connecting rod (321) is hinged to the first slider (311), the upper end of the first connecting rod (321) is hinged to the lower end of the third connecting rod (323), the upper end of the third connecting rod (323) is hinged to the first connecting piece (33), the lower end of the second connecting rod (322) is hinged to the second slider (312), the upper end of the second connecting rod (322) is hinged to the lower end of the fourth connecting rod (324), and the upper end of the fourth connecting rod (324) is hinged to the first connecting piece (33). The first connecting rod (321) and the second connecting rod (322) are arranged in cross and hinged to each other by a first pin shaft (325), and the third connecting rod (323) and the fourth connecting rod (324) are hinged to the first connecting piece (33) by a second pin shaft (326).

5. The scissor-fork four-degree-of-freedom parallel mechanism according to claim 4, characterized in that, The second double-layer scissor mechanism (42) is arranged in the same structure as the first double-layer scissor mechanism (32).

6. The scissor-fork four-degree-of-freedom parallel mechanism according to claim 5, characterized in that, When the first slider (311), the second slider (312), the third slider (411) and the fourth slider (412) move synchronously and in the same direction, the moving platform (2) moves horizontally in the front-back direction; When the first slider (311) and the second slider (312), and the third slider (411) and the fourth slider (412) move synchronously and simultaneously towards each other or in the opposite direction, the moving platform (2) moves horizontally in the up-down direction; When the first slider (311) and the second slider (312) move synchronously in the opposite direction, and the third slider (411) and the fourth slider (412) move synchronously towards each other, the moving platform (2) moves horizontally to the right, and vice versa, the moving platform (2) moves horizontally to the left; When the first slider (311) and the second slider (312) move synchronously in the same direction, and the third slider (411) and the fourth slider (412) move synchronously in the opposite direction, the moving platform (2) rotates around the vertical axis.

7. The scissor-fork four-degree-of-freedom parallel mechanism according to claim 1, wherein The first parallelogram linkage (34) comprises two connecting rods (341) which are spaced apart and parallel, one end of the connecting rod (341) is hinged with the first connecting piece (33), and the other end of the connecting rod (341) is hinged with the third connecting piece (43).

8. The scissor-fork four-degree-of-freedom parallel mechanism according to claim 7, characterized in that, The second parallelogram linkage (44) is arranged in the same structure as the first parallelogram linkage (34).

Images