Four-degree-of-freedom parallel mechanism driven by coplanar moving pair

Abstract

The invention relates to the technical field of parallel mechanisms, in particular to a four-degree-of-freedom parallel mechanism driven by coplanar moving pairs, which comprises a movable platform and a fixed platform which are arranged from top to bottom, and a first fixed rod and a second fixed rod which are used for supporting and adjusting the posture of the movable platform are movably arranged between the movable platform and the fixed platform; the number of the first fixed rods is two, the number of the second fixed rods is two, and the bottoms of the first fixed rods and the bottoms of the second fixed rods linearly move on the top of the fixed platform. The first fixed rod length and the second fixed rod length are each of a fixed-length rod structure, the moving directions of the bottoms of the first fixed rod length and the second fixed rod length are perpendicular to each other, the structural stability is higher, the rigidity of the mechanism in the vertical direction is greatly improved, meanwhile, a linear driving module with a driving motor matched with a lead screw is adopted, and the stability of the mechanism is improved. And all the mechanisms are integrated on the fixed platform, the driving mode is unified, the layout is regular, the mechanism operation is more stable, and the control difficulty is reduced.

Description

Technical Field

[0001] This invention relates to the field of parallel mechanism technology, specifically to a four-degree-of-freedom parallel mechanism driven by a coplanar prismatic pair. Background Technology

[0002] Parallel robot mechanisms, due to their dynamic platform being connected to the static platform through multiple independent branches, possess advantages such as strong load-bearing capacity, high motion accuracy, high rigidity, and fast dynamic response, and are widely used in high-end manufacturing, precision assembly, high-speed sorting, and other fields.

[0003] The degrees of freedom of parallel robots are the core basis for their classification and design, directly determining their essential differences in structure, performance, and application. Among them, six-degree-of-freedom parallel mechanisms generally suffer from drawbacks such as small workspace, complex structure, and easy interference between links and between links and joints; while four-degree-of-freedom parallel mechanisms, although relatively simple in structure and easier to control, have become the ideal choice.

[0004] However, existing four-degree-of-freedom parallel mechanisms generally suffer from problems such as unreasonable arrangement of drive pairs, poor structural symmetry, limited workspace, and numerous singular configurations, which restricts the usability of the mechanisms. In addition, existing four-degree-of-freedom parallel mechanisms often use telescopic cylinders as drives to reduce the number of branches, which greatly reduces the overall stiffness of the mechanism.

[0005] Therefore, designing a four-degree-of-freedom parallel mechanism with symmetrical structure, clear constraints, and a driving method that is conducive to improving workspace and stiffness performance has important research value and broad application prospects. Summary of the Invention

[0006] The purpose of this invention is to provide a four-degree-of-freedom parallel mechanism driven by coplanar kinetic pairs, in order to solve problems such as unreasonable arrangement of drive pairs, poor structural symmetry, limited workspace and many singular configurations, as well as the problem that the use of telescopic cylinders as drives reduces the number of branches and lowers the overall stiffness of the mechanism.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a four-degree-of-freedom parallel mechanism driven by a coplanar prismatic pair, comprising:

[0008] A moving platform and a fixed platform are arranged from top to bottom, and a first fixed rod length and a second fixed rod length are movably provided between the moving platform and the fixed platform to support and adjust the posture of the moving platform.

[0009] There are two of each of the first and second fixed pole lengths. The bottom of the first and second fixed pole lengths moves linearly to the top of the fixed platform, and the linear movement trajectories of the bottom of the first and second fixed pole lengths are set vertically, so that different combinations of the bottom movement of the first and second fixed pole lengths drive the platform to adjust its attitude.

[0010] Preferably, the top of the first fixed length rod is fixedly connected with a hinged frame, and the top of the hinged frame is hingedly connected with a hinged seat, which is fixedly connected to the bottom of the movable platform.

[0011] Preferably, the top of the second fixed length rod is fixedly connected with a spherical hinge, and the top of the spherical hinge is hingedly connected with a spherical hinge support, which is fixedly connected to the bottom of the movable platform.

[0012] Preferably, the two hinged seats and the two spherical hinge supports are arranged in a ring shape and uniformly distributed on the bottom of the movable platform, and the hinged seats and the spherical hinge supports are respectively located at both ends of the bottom of the movable platform, and the two hinged seats and the two spherical hinge supports are symmetrically arranged.

[0013] Preferably, the bottom of the first fixed length rod and the bottom of the second fixed length rod are respectively fixedly connected with a hinged seat, and the bottom of the hinged seat is hingedly connected with a hinged seat support, and the hinged seat support is linearly movably connected to the top of the fixed platform, and the middle part of the fixed platform is a hollow structure.

[0014] Preferably, the top of the fixed platform corresponding to the position of the hinged seat support is fixedly connected with a fixed seat, the top of the fixed seat is fixedly connected with a driving frame, the inner wall of the driving frame is movably connected with a sliding block, and the hinged seat support is fixedly connected to the top of the sliding block, the middle part of the sliding block is threadedly connected with a lead screw, and the lead screw is rotatably connected to the middle part of the driving frame through a bearing, one end of the lead screw is fixedly connected with a driving motor, and the driving motor is fixedly connected to one end of the driving frame.

[0015] Preferably, the inner wall of the driving frame is fixedly connected with a sliding rail, and the sliding block is movably connected to the surface of the sliding rail, so that the sliding rail guides the movement of the sliding block.

[0016] Preferably, the driving frame corresponding to the first fixed length rod is arranged perpendicular to the driving frame corresponding to the second fixed length rod, and the driving frames corresponding to the two first fixed length rods are arranged in parallel.

[0017] Compared with the prior art, the present application has the following advantages:

[0018] 1、The first fixed length rod and the second fixed length rod of the present application both adopt fixed length rod structure, and the moving directions of the two groups of first fixed length rods and second fixed length rods at the bottom are perpendicular to each other, which has stronger structural stability, greatly improves the rigidity of the mechanism in the vertical direction, and has significantly better carrying capacity than the traditional telescopic cylinder driving mechanism. The driving of the first fixed length rod and the second fixed length rod of the present application adopts a linear driving module of driving motor cooperating with lead screw, and all are integrated on the fixed platform. The driving mode is unified and the layout is regular, which not only makes the mechanism run more smoothly, but also reduces the control difficulty. At the same time, the characteristics of the linear driving module give the mechanism higher control precision and faster dynamic response speed.

[0019] 2. This invention also significantly improves the overall symmetry of the mechanism by using two sets of identical first and second fixed rod lengths, with the corresponding drive frames arranged perpendicularly to each other. Simultaneously, the identical first and second fixed rod lengths improve component interchangeability, simplify the production process, and effectively reduce manufacturing and subsequent maintenance costs. Through the symmetrical layout of the first and second fixed rod lengths, the rational positioning of the hinge seats and ball joint supports, and the coordination of the first and second fixed rod lengths with various types of hinge nodes, the movement range of the mechanism is effectively expanded. At the same time, the risk of interference between rods and between rods and joints during movement is reduced, significantly decreasing the number of singular configurations and greatly improving the usability and movement flexibility of the mechanism. Furthermore, the first and second fixed rod lengths are subjected only to tension and compression, which can significantly improve the internal force distribution during operation, thereby enhancing the overall structural strength and resistance to deformation. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of a four-degree-of-freedom parallel mechanism driven by a coplanar prismatic pair according to the present invention.

[0021] Figure 2 This is a schematic diagram of a fixed platform structure for a four-degree-of-freedom parallel mechanism driven by a coplanar kinetic pair according to the present invention.

[0022] Figure 3 This is a schematic diagram of a four-degree-of-freedom parallel mechanism motion platform driven by a coplanar prismatic pair according to the present invention.

[0023] Figure 4 This is a schematic diagram of the first fixed link length structure of a four-degree-of-freedom parallel mechanism driven by a coplanar prismatic pair according to the present invention;

[0024] Figure 5 This is a schematic diagram of the second fixed link length structure of a four-degree-of-freedom parallel mechanism driven by a coplanar moving pair according to the present invention.

[0025] In the diagram: 1. Moving platform; 2. First fixed rod length; 3. Second fixed rod length; 4. Fixed platform; 5. Hooke's hinge; 6. Hooke's hinge support; 7. Slider; 8. Drive frame; 9. Lead screw; 10. Drive motor; 11. Slide rail; 12. Fixed seat; 13. Hinge seat; 14. Hinge frame; 15. Ball joint support; 16. Ball joint. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please see Figures 1-5 This invention provides a technical solution: a four-degree-of-freedom parallel mechanism driven by a coplanar prismatic pair, comprising:

[0028] A moving platform 1 and a fixed platform 4 are arranged from top to bottom. A first fixed rod length 2 and a second fixed rod length 3 are movably provided between the moving platform 1 and the fixed platform 4 to support and adjust the posture of the moving platform 1.

[0029] There are two of each of the first fixed rod length 2 and the second fixed rod length 3. The bottom of the first fixed rod length 2 and the second fixed rod length 3 linearly move at the top of the fixed platform 4, and the linear movement trajectories of the bottom of the first fixed rod length 2 and the second fixed rod length 3 are set vertically so that different combinations of the bottom movement of the first fixed rod length 2 and the second fixed rod length 3 drive the moving platform 1 to adjust its attitude. A hinge frame 14 is fixedly installed on the top of the first fixed rod length 2, and a hinge seat 13 is hinged to the top of the hinge frame 14. The hinge seat 13 is fixedly installed at the bottom of the moving platform 1. The top of the second fixed rod length 3... A ball joint 16 is fixedly installed on the bottom of the moving platform 1, and a ball joint support 15 is hinged to the top of the ball joint 16. The ball joint support 15 is fixedly installed on the bottom of the moving platform 1. Two hinge seats 13 and two ball joint supports 15 are evenly distributed in a ring at the bottom of the moving platform 1. That is, the first fixed rod length 2 and the second fixed rod length 3 are located at both ends of the moving platform 1, and the two first fixed rod lengths 2 and the two fixed rod lengths 3 are also symmetrically arranged. The hinge seats 13 and the ball joint supports 15 are located at both ends of the bottom of the moving platform 1, and the two hinge seats 13 and the two ball joint supports 15 are symmetrically arranged.

[0030] When in use, the above structure moves linearly at the bottom of the first fixed rod length 2 and the second fixed rod length 3. The first fixed rod length 2 is hinged to the bottom of the moving platform 1 through the hinge frame 14 and the hinge seat 13, and the second fixed rod length 3 is hinged to the bottom of the moving platform 1 through the ball joint 16 and the ball joint support 15. This allows the attitude adjustment of the moving platform 1 to be achieved through different combinations of linear movement of the bottom of the first fixed rod length 2 and the second fixed rod length 3.

[0031] Hooke hinges 5 are fixedly installed at the bottom of both the first fixed rod length 2 and the second fixed rod length 3. A Hooke hinge support 6 is hinged to the bottom of each Hooke hinge 5, and the Hooke hinge support 6 is linearly and movably connected to the top of the fixed platform 4. The middle part of the fixed platform 4 has a hollow structure to reduce its weight. A fixed seat 12 is fixedly installed at the top of the fixed platform 4 corresponding to the position of the Hooke hinge support 6. A drive frame 8 is fixedly installed on the top of the fixed seat 12. A slider 7 is movably connected to the inner wall of the drive frame 8, and the Hooke hinge support 6 is fixedly installed on the top of the slider 7. A lead screw 9 is threadedly connected to the drive frame 8, and the lead screw 9 is rotatably connected to the middle of the drive frame 8 through a bearing. A drive motor 10 is fixedly installed at one end of the lead screw 9, and the drive motor 10 is fixedly installed at one end of the drive frame 8. A slide rail 11 is fixedly installed on the inner wall of the drive frame 8, and a slider 7 is movably connected to the surface of the slide rail 11 so that the slide rail 11 guides the movement of the slider 7. The drive frame 8 corresponding to the first fixed rod length 2 and the drive frame 8 corresponding to the second fixed rod length 3 are arranged perpendicular to each other, and are arranged parallel to each other.

[0032] When the above structure is in use, the drive motor 10 drives the lead screw 9 to rotate, and the lead screw 9 drives the slider 7 to move. By setting the slide rail 11, the slider 7 moves smoothly on the inner wall of the drive frame 8 under the guidance of the slide rail 11. The slider 7 drives the bottom of the first fixed rod length 2 and the second fixed rod length 3 to move linearly through the Hooke hinge support 6 and the Hooke hinge 5 respectively.

[0033] Working principle: In use, the invention drives the lead screw 9 to rotate by energizing the drive motor 10, which in turn drives the slider 7 to move. By setting the slide rail 11, the slider 7 moves smoothly on the inner wall of the drive frame 8 under the guidance of the slide rail 11. The slider 7 drives the bottom of the first fixed rod length 2 and the second fixed rod length 3 to move linearly through the Hooke hinge support 6 and the Hooke hinge 5 respectively. The first fixed rod length 2 is hinged to the bottom of the moving platform 1 through the hinge frame 14 and the hinge seat 13, and the second fixed rod length 3 is hinged to the bottom of the moving platform 1 through the ball joint 16 and the ball joint support 15. This allows the attitude adjustment of the moving platform 1 to be achieved by different combinations of the linear movement of the bottom of the first fixed rod length 2 and the second fixed rod length 3, as shown in the following figure.

[0034] The x-axis is defined as the length direction of the drive frame 8 corresponding to the second fixed rod length 3, and the y-axis is defined as the length direction of the drive frame 8 corresponding to the first fixed rod length 2. The z-axis is perpendicular to the fixed platform 4 and points from the lower surface to the upper surface. The y-axis conforms to the right-hand rule. In this invention, the lead screw 9 is selected as the driving component. By relying on the mutual cooperation between the first fixed rod length 2 and the second fixed rod length 3, the control of the moving platform 1 can be achieved in four degrees of freedom: two movements and two rotations.

[0035] The drive motor 10 corresponding to the first fixed rod length 2 drives the lead screw 9 to rotate, so that the two sliders 7 move equidistantly along the slide rail 11 in the same direction. The drive motor 10 corresponding to the second fixed rod length 3 drives the lead screw 9 to rotate, so that the two sliders 7 move unequally along the slide rail 11 in opposite directions. This can realize the degree of freedom of movement of the moving platform 1 on the y-axis.

[0036] The drive motor 10 corresponding to the first fixed rod length 2 drives the lead screw 9 to rotate, so that the two sliders 7 move equidistantly along the slide rail 11 in a mirror image. The drive motor 10 corresponding to the second fixed rod length 3 drives the lead screw 9 to rotate, so that the two sliders 7 move equidistantly along the slide rail 11 in the same direction. This can realize the degree of freedom of movement of the moving platform 1 in the z-axis.

[0037] The drive motor 10 corresponding to the first fixed rod length 2 drives the lead screw 9 to rotate, so that the two sliders 7 move equidistantly along the slide rail 11 in the same direction, and locks the lead screw 9 corresponding to the second fixed rod length 3, thus realizing the degree of freedom of the moving platform 1 to rotate around the x-axis.

[0038] The drive motor 10 corresponding to the second fixed rod length 3 drives the lead screw 9 to rotate, so that the two sliders 7 move equidistantly along the slide rail 11 in the same direction, and locks the lead screw 9 corresponding to the first fixed rod length 2, so that the moving platform 1 can realize the degree of freedom of rotation around the y axis.

[0039] Ultimately, by coordinating the first fixed rod length 2 and the second fixed rod length 3 with the lead screw 9, slider 7, Hooke hinge support 6, and Hooke hinge 5 in different directions and with different moving distances, the moving platform 1 can achieve four degrees of freedom: the moving degree of freedom along the y and z axes and the rotational degree of freedom around the x and y axes. Furthermore, the drive frames 8 corresponding to the first fixed rod length 2 and the second fixed rod length 3 are arranged perpendicularly to each other, ensuring that the moving trajectories at the bottom of the first fixed rod length 2 and the second fixed rod length 3 are vertically set. Since both the first fixed rod length 2 and the second fixed rod length 3 are fixed-length rods, the overall mechanism has high rigidity and load-bearing capacity in the vertical direction. Simultaneously, the drive of the first fixed rod length 2 and the second fixed rod length 3 is linearly driven by the drive motor 10 and the lead screw 9, and both are placed on the fixed platform 4, resulting in smooth operation, easy control, higher control precision, and faster response speed. The use of two sets of first fixed rod length 2 and second fixed rod length 3 structures is simple, has good interchangeability, and reduces manufacturing and maintenance costs.

[0040] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A planar parallel mechanism with four degrees of freedom driven by a planar prismatic pair, characterized in that: Include: The movable platform (1) and the fixed platform (4) are arranged from top to bottom, the first fixed rod length (2) and the second fixed rod length (3) are movably arranged between the movable platform (1) and the fixed platform (4) for supporting and adjusting the posture of the movable platform (1); The number of the first fixed rod length (2) and the second fixed rod length (3) is two respectively, the linear movement of the bottom of the first fixed rod length (2) and the second fixed rod length (3) is on the top of the fixed platform (4), and the linear movement tracks of the bottom of the first fixed rod length (2) and the second fixed rod length (3) are arranged vertically, so that different combinations of the movement of the bottom of the first fixed rod length (2) and the second fixed rod length (3) drive the movable platform (1) to adjust the posture.

2. The planar parallel mechanism of claim 1, wherein: The top of the first fixed rod length (2) is fixedly connected with the hinged frame (14), and the top of the hinged frame (14) is hingedly connected with the hinged seat (13), and the hinged seat (13) is fixedly connected to the bottom of the movable platform (1).

3. The planar parallel mechanism of claim 2, wherein: The top of the second fixed rod length (3) is fixedly connected with the spherical hinge (16), and the top of the spherical hinge (16) is hingedly connected with the spherical hinge support (15), and the spherical hinge support (15) is fixedly connected to the bottom of the movable platform (1).

4. The planar parallel mechanism of claim 3, wherein: The two hinged seats (13) and the two spherical hinge supports (15) are arranged in a ring shape and uniformly distributed on the bottom of the movable platform (1), the hinged seat (13) and the spherical hinge support (15) are located at both ends of the bottom of the movable platform (1), and the two hinged seats (13) and the two spherical hinge supports (15) are symmetrically arranged.

5. The planar parallel mechanism of claim 4, wherein: The bottom of the first fixed rod length (2) and the second fixed rod length (3) is respectively fixedly connected with the hinged seat (13), and the hinged seat (13) is hingedly connected with the hinged seat (13), and the hinged seat (13) is hingedly connected with the hinged seat (13). The hinged seat (6) is linearly movably connected to the top of the fixed platform (4), and the middle part of the fixed platform (4) is a hollow structure.

6. The planar parallel mechanism of claim 5, wherein: The top of the fixed platform (4) corresponding to the position of the hinged seat (6) is fixedly connected with the fixed seat (12), the top of the fixed seat (12) is fixedly connected with the driving frame (8), the inner wall of the driving frame (8) is movably connected with the sliding block (7), and the hinged seat (6) is fixedly connected to the top of the sliding block (7). The middle part of the sliding block (7) is threadedly connected with the lead screw (9), and the lead screw (9) is rotatably connected to the middle part of the driving frame (8) through a bearing, one end of the lead screw (9) is fixedly connected with the driving motor (10), and the driving motor (10) is fixedly connected to one end of the driving frame (8).

7. The planar parallel mechanism of claim 6, wherein: The inner wall of the driving frame (8) is fixedly connected with the sliding rail (11), and the sliding block (7) is movably connected to the surface of the sliding rail (11), so that the sliding rail (11) guides the movement of the sliding block (7).

8. The planar parallel mechanism of claim 7, wherein: The driving frame (8) corresponding to the first fixed rod length (2) and the driving frame (8) corresponding to the second fixed rod length (3) are arranged vertically, and the driving frame (8) corresponding to the two first fixed rod lengths (2) is arranged parallelly.

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