Motion decoupling mechanism based on four-connecting-rod flexible angle structure

Abstract

The invention discloses a motion decoupling mechanism based on a four-connecting-rod flexible angle structure, which belongs to the field of precision machinery and comprises a shell, a transmission rod capable of linearly moving is arranged on the shell, and one end, extending to the outside of the shell, of the transmission rod is connected with an output end. The other end, extending out of the shell, of the transmission rod is connected with the input end through a flexible angle connecting rod mechanism, the transmission rod can filter the non-target freedom degree input by the input end through the flexible angle connecting rod mechanism, and the transmission rod achieves single-freedom-degree linear motion in the direction of the transmission rod through a four-connecting-rod flexible angle mechanism arranged in the shell. And the flexible angle connecting rod mechanism is matched with the four-connecting-rod flexible angle mechanism to realize motion decoupling. According to the motion decoupling mechanism based on the four-connecting-rod flexible angle structure, the transmission rod fixed to the four-connecting-rod flexible angle structure only allows single-degree-of-freedom linear motion in the direction of the transmission rod, final filtering of noise is achieved, pure single-degree-of-freedom motion is obtained, and the motion decoupling function is completed.

Description

Technical Field

[0001] The present invention relates to the field of precision machinery technology, and in particular to a motion decoupling mechanism based on a four-link soft angle structure. Background Art

[0002] In ultra-precision manufacturing (such as photolithography machines), precision measurement (such as atomic force microscopes) and cutting-edge scientific research, environmental vibration is a key factor that restricts equipment from achieving nanometer / sub-nanometer precision, and high-performance vibration isolation platforms are the basis for achieving stable operation of equipment. However, traditional vibration isolation platforms generally have the core problem of motion coupling: when the input end is subjected to complex vibrations in six degrees of freedom in space (three translations and three rotations), the support or elastic structure inside the platform cannot completely isolate the mutual interference between different degrees of freedom, resulting in vibration input in one direction inducing parasitic motion in other directions, and conversely, the target compensation motion of the platform will also interfere with irrelevant degrees of freedom. This coupling effect seriously damages the stability, control accuracy and dynamic performance of the vibration isolation platform, especially in designs that pursue extremely low natural frequencies. Therefore, the development of a mechanism that can achieve complete motion decoupling has become a key challenge to improving the performance of high-end vibration isolation platforms.

[0003] Currently, there are two main solutions in the existing technology:

[0004] 1. Decoupling mechanism based on traditional elastic hinges / flexible joints: This solution uses flexible elements (leaf springs, wire-cut hinges) arranged in a specific geometric configuration (such as parallelograms or cross-links) to connect platform components. The goal is to allow the target translational degree of freedom through low stiffness, while relying on high stiffness to suppress other degrees of freedom. However, its core flaw is incomplete motion decoupling: when the flexible element deforms, its rotation center / stiffness center drifts, resulting in significant parasitic motion (such as translation accompanied by undesired rotation), and it is difficult to achieve uniform high stiffness (especially rotational degrees of freedom) in all non-working directions, which often conflicts with the low-frequency performance requirements in the working direction.

[0005] 2. Based on the combination of precision guide mechanisms and decoupling bearings: This solution uses high-precision linear guide elements (cross roller guides, air bearing guides) to strictly constrain the platform to single-axis translation, supplemented by decoupling elements (ball joints, universal joints, flexible connections) to absorb guide errors or rotational coupling caused by external forces. The main problem is also incomplete motion decoupling: the inherent nonlinear effects of friction, creep (mechanical) or air hammer (air bearing) in the guide elements destroy the smoothness of motion; the rotational freedom provided by the decoupling elements is limited and the center is fixed, which has poor isolation effect on the linearity / angular motion errors of the guide rail itself. There is residual stiffness in the decoupling direction, and zero-stiffness decoupling cannot be achieved.

[0006] The common core defect of the above-mentioned existing technologies is incomplete motion decoupling, which leads to parasitic motion and residual coupling stiffness at the output end, seriously restricting the stability and accuracy improvement of the vibration isolation platform. Summary of the Invention

[0007] The purpose of the present invention is to propose a motion decoupling mechanism based on a four-bar soft angle structure in order to solve the problem that the existing motion decoupling mechanism has incomplete motion decoupling, resulting in parasitic motion and residual coupling stiffness at the output end, which seriously restricts the stability and accuracy improvement of the vibration isolation platform.

[0008] To achieve the above objectives, the present invention adopts the following technology: a motion decoupling mechanism based on a four-bar soft-angle structure, comprising a housing, a transmission rod capable of linear motion disposed on the housing, one end of the transmission rod extending outside the housing being connected to an output end, and the other end of the transmission rod extending outside the housing being connected to an input end via a soft-angle linkage mechanism;

[0009] The transmission rod can filter non-target degrees of freedom input at the input end through a soft-angle linkage mechanism. The transmission rod realizes single-degree-of-freedom linear motion along the direction of the transmission rod through a four-bar soft-angle linkage mechanism arranged in the shell. The soft-angle linkage mechanism cooperates with the four-bar soft-angle linkage mechanism to realize motion decoupling.

[0010] As a further description of the above technical solution: the flexible angle link mechanism includes a horizontal flexible angle link and a vertical flexible angle link arranged in sequence along the output direction of the transmission rod, wherein the horizontal flexible angle link and the vertical flexible angle link are fixedly connected and arranged perpendicular to each other, and the axial direction of the horizontal flexible angle link and the vertical flexible angle link is the same as the axial direction of the transmission rod.

[0011] As a further description of the above technical solution: the four-bar linkage flexible angle mechanism includes oblique parallel flexible angle links and straight parallel flexible angle links arranged in the shell, wherein the straight parallel flexible angle links are arranged perpendicular to the transmission rod.

[0012] As a further description of the above technical solution: a triangular conversion block is provided between the ends of the oblique parallel soft-angle connecting rod and the straight parallel soft-angle connecting rod, and the triangular conversion block is a triangular block structure.

[0013] As a further description of the above technical solution: the horizontal soft-angle connecting rod, the vertical soft-angle connecting rod, the oblique parallel soft-angle connecting rod and the straight parallel soft-angle connecting rod are all elastic structures, and their operation depends on the elastic deformation of the material.

[0014] As a further description of the above technical solution: the materials of the horizontal soft angle connecting rod, the vertical soft angle connecting rod, the oblique parallel soft angle connecting rod and the straight parallel soft angle connecting rod are metal elastic materials.

[0015] As a further description of the above technical solution: the axial direction of the transmission rod is the direction of the target linear degree of freedom.

[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0017] 1. Through the design of soft-angle structures and their precise spatial arrangement, a low-stiffness path is provided in the target working direction (such as Z-direction translation), while extremely high and uniform stiffness is achieved in the other five non-working degrees of freedom (X / Y translation, Rx / Ry / Rz rotation), and the deformation center is ensured to be highly stable. As a result, the complex six-degree-of-freedom vibration energy at the input end is forcibly guided to the only low-stiffness target direction for transmission / dissipation, thereby strictly limiting the output end to single-degree-of-freedom linear motion. This fundamentally solves the core defect of incomplete motion decoupling in existing technologies, significantly eliminates parasitic motion and residual coupling response, and greatly improves the stability and control accuracy of the vibration isolation platform.

[0018] 2. The core soft-angle structure is a monolithic or quasi-monolithic elastic structure that operates entirely through the elastic deformation of the material. It requires no sliding / rolling contact pairs (such as mechanical guides) or external energy input (such as electromagnetic coils). This completely eliminates nonlinear interference sources such as friction and creep in mechanical guides, air hammer in air-bearing guides, and heat generation from electromagnetic negative stiffness solutions. Within the designed linear displacement range, the force-displacement relationship exhibits excellent linearity, ensuring smooth and high-fidelity output motion, meeting the demanding linear motion requirements of ultra-high-precision applications.

[0019] 3. The soft-angle structure can achieve highly integrated complex functions through precision processing (such as wire cutting and additive manufacturing), without relying on expensive, precise and fragile purchased components such as linear guides, ball joints, universal joints and their complicated assembly and debugging processes. The structure is simple, with a small number of parts, no wear parts, and no need for external support systems (such as continuous air supply). While achieving better decoupling performance, it significantly reduces the complexity of the system, potential manufacturing costs and assembly difficulty, and greatly improves the reliability of long-term operation.

[0020] 4. The flexible angle structure has the ability to independently and precisely control the stiffness of each degree of freedom. Through topology optimization and parametric design, it can achieve the extremely low stiffness required by the design in the target working direction (such as the Z direction) (to meet the ultra-low frequency vibration isolation requirements), while achieving extremely high and uniform stiffness in all non-working degrees of freedom (to ensure complete decoupling). This resolves the conflict in the traditional flexible hinge solution of "increasing stiffness in the non-working direction and sacrificing low-frequency performance in the working direction", achieving the ideal coexistence of low working stiffness and high decoupling stiffness, and expanding the performance boundaries of the vibration isolation platform. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 shows a plan view provided in an embodiment of the present invention;

[0022] Figure 2 A schematic diagram of the overall structure provided according to an embodiment of the present invention is shown.

[0023] Legend:

[0024] 1. Input end; 2. Horizontal soft-angle connecting rod; 3. Vertical soft-angle connecting rod; 4. Housing; 5. Triangular adapter block; 6. Oblique parallel soft-angle connecting rod; 7. Transmission rod; 8. Straight parallel soft-angle connecting rod; 9. Output end. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] Reference Figure 1 - Figure 2 This embodiment provides a motion decoupling mechanism based on a four-bar soft-angle structure, comprising a housing 4, on which is disposed a transmission rod 7 capable of linear motion. One end of the transmission rod 7 extending outside the housing 4 is connected to an output end 9, and the other end of the transmission rod 7 extending outside the housing 4 is connected to an input end 1 via a soft-angle linkage mechanism.

[0027] The transmission rod 7 can filter the non-target degrees of freedom input from the input end 1 through the soft-angle linkage mechanism. The transmission rod 7 realizes single-degree-of-freedom linear motion along the direction of the transmission rod through the four-bar soft-angle linkage mechanism set in the shell 4. The soft-angle linkage mechanism cooperates with the four-bar soft-angle linkage mechanism to realize motion decoupling.

[0028] In the present invention, the complex motion of six degrees of freedom (three translations and three rotations) in space input by the input end 1 is first filtered by the soft-angle linkage mechanism to eliminate most of the non-target degrees of freedom (such as three rotational degrees of freedom and two linear degrees of freedom). The remaining motion containing the target degrees of freedom and a small amount of noise is transmitted to the four-bar soft-angle mechanism in the shell 4. The transmission rod 7 is further constrained by the four-bar soft-angle mechanism, and is only allowed to perform linear motion along its own axis. Finally, the pure single-degree-of-freedom motion is transmitted to the output end 9 through the transmission rod 7. Through the synergistic effect of the soft-angle linkage mechanism and the four-bar soft-angle mechanism, the coupling problem of "motion in one direction inducing parasitic motion in other directions" in the traditional mechanism is completely eliminated, so that the output end 9 only retains the single-degree-of-freedom linear motion along the direction of the transmission rod 7.

[0029] Specifically, the flexible angle link mechanism includes a horizontal flexible angle link 2 and a vertical flexible angle link 3 sequentially arranged along the output direction of the transmission rod 7, wherein the horizontal flexible angle link 2 and the vertical flexible angle link 3 are fixedly connected and arranged perpendicular to each other, and the axial directions of the horizontal flexible angle link 2 and the vertical flexible angle link 3 are the same as the axial direction of the transmission rod 7. It should be noted that the axial direction of the transmission rod 7 is the direction of the target linear degree of freedom;

[0030] The four-bar soft angle mechanism includes an oblique parallel soft angle link 6 and a straight parallel soft angle link 8 arranged in an outer shell 4, wherein the straight parallel soft angle link 8 is arranged vertically to the transmission rod 7, and a triangular conversion block 5 is arranged between the ends of the oblique parallel soft angle link 6 and the straight parallel soft angle link 8. The triangular conversion block 5 is a triangular block structure, and the horizontal soft angle link 2, the vertical soft angle link 3, the oblique parallel soft angle link 6 and the straight parallel soft angle link 8 are all elastic structures, and their operation depends on the elastic deformation of the material.

[0031] When the input end 1 inputs a complex motion with six degrees of freedom (three translations and three rotations) in space, the horizontal flexible link 2 and the vertical flexible link 3 utilize the stiffness characteristics of their own elastic structures to form constraints through a mutually perpendicular arrangement: the horizontal flexible link 2 mainly suppresses lateral motion perpendicular to its own axis and rotation around non-target axes, while the vertical flexible link 3 further filters the remaining non-target degrees of freedom, thereby prioritizing the retention of the target linear degrees of freedom that are consistent with the axis direction of the transmission rod 7, and preliminarily filtering out most of the interference from non-target degrees of freedom;

[0032] In the four-bar flexible angle mechanism, the oblique parallel flexible angle link 6 and the straight parallel flexible angle link 8 are connected by the triangular conversion block 5 to form a cooperative constraint structure. The straight parallel flexible angle link 8 is arranged perpendicular to the transmission rod 7. Because the horizontal flexible angle link 2, the vertical flexible angle link 3, the oblique parallel flexible angle link 6, and the straight parallel flexible angle link 8 are all elastic structures that rely on material elastic deformation, when the motion initially filtered by the flexible angle link mechanism is transmitted to the triangular conversion block 5, the oblique parallel flexible angle link 6 and the straight parallel flexible angle link 8 use their own elastic properties to further restrict the motion direction of the transmission rod 7, allowing it to move only along its own axis (the target linear degree of freedom direction) while suppressing displacement and rotation in other non-target directions. The triangular conversion block 5, through the stability of the triangular structure, smoothly transfers the force and motion transmitted by the flexible angle link mechanism to the four-bar flexible angle mechanism, ensuring a clear force flow transmission path and reliable constraint. This allows for precise filtering of residual non-target degree of freedom noise after the initial decoupling, ultimately achieving pure single-degree-of-freedom linear motion of the transmission rod 7 along the target direction, completing complete decoupling.

[0033] It should be noted that the horizontal flexible angle link 2, vertical flexible angle link 3, oblique parallel flexible angle link 6, and straight parallel flexible angle link 8 are made of metallic elastic material. Metallic elastic material has a stable elastic modulus and linear deformation range, ensuring controllable stiffness characteristics of each flexible angle link when filtering non-target degrees of freedom and constraining the transmission direction, thus avoiding deviations in the decoupling effect caused by fluctuations in material properties. Furthermore, metallic materials are easily processed into complex geometric configurations through processes such as wire cutting and precision grinding, meeting the dimensional accuracy and structural symmetry requirements of the flexible angle links and ensuring consistent motion when the links work together.

[0034] Among them, the optional metal elastic materials include spring steel, elastic alloy, titanium alloy, etc.

[0035] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A motion decoupling mechanism based on a four-bar soft-angle structure, characterized in that: The invention comprises a housing (4), wherein a transmission rod (7) capable of linear movement is provided on the housing (4), wherein one end of the transmission rod (7) extending outside the housing (4) is connected to an output end (9), and the other end of the transmission rod (7) extending outside the housing (4) is connected to an input end (1) via a flexible angle link mechanism; The transmission rod (7) can filter non-target degrees of freedom inputted from the input end (1) through a soft-angle linkage mechanism, and the transmission rod (7) realizes single-degree-of-freedom linear motion along the transmission rod direction through a four-bar soft-angle linkage mechanism arranged in a housing (4). The soft-angle linkage mechanism cooperates with the four-bar soft-angle linkage mechanism to realize motion decoupling.

2. The motion decoupling mechanism based on a four-bar soft-angle structure according to claim 1, characterized in that: The flexible angle link mechanism comprises a horizontal flexible angle link (2) and a vertical flexible angle link (3) sequentially arranged along the output direction of a transmission rod (7), wherein the horizontal flexible angle link (2) and the vertical flexible angle link (3) are fixedly connected and arranged perpendicular to each other, and the axial directions of the horizontal flexible angle link (2) and the vertical flexible angle link (3) are the same as the axial direction of the transmission rod (7).

3. The motion decoupling mechanism based on a four-bar soft-angle structure according to claim 2, characterized in that: The four-link soft angle mechanism comprises oblique parallel soft angle links (6) and straight parallel soft angle links (8) arranged in a housing (4), wherein the straight parallel soft angle links (8) and the transmission rod (7) are arranged vertically.

4. The motion decoupling mechanism based on a four-bar soft-angle structure according to claim 3, characterized in that: A triangular conversion block (5) is provided between the ends of the oblique parallel soft-angle connecting rod (6) and the straight parallel soft-angle connecting rod (8), and the triangular conversion block (5) is a triangular block structure.

5. The motion decoupling mechanism based on a four-bar soft-angle structure according to claim 3 or 4, characterized in that: The horizontal flexible angle connecting rod (2), the vertical flexible angle connecting rod (3), the oblique parallel flexible angle connecting rod (6) and the straight parallel flexible angle connecting rod (8) are all elastic structures, and their operation depends on the elastic deformation of the material.

6. The motion decoupling mechanism based on a four-bar soft-angle structure according to claim 5, characterized in that: The horizontal flexible angle connecting rod (2), the vertical flexible angle connecting rod (3), the oblique parallel flexible angle connecting rod (6) and the straight parallel flexible angle connecting rod (8) are made of metal elastic material.

7. The motion decoupling mechanism based on a four-bar soft-angle structure according to claim 1, characterized in that: The axial direction of the transmission rod (7) is the target linear degree of freedom direction.

Images