Single degree of freedom planar two-dimensional deployable basic unit and large-scale deployable device

Abstract

The application discloses a single-degree-of-freedom planar two-dimensional deployable basic unit and a large-scale deployable device. The deployable basic unit is a symmetrical quadrangular prism multi-closed-loop mechanism, which comprises two platforms arranged in parallel, and a driving branch chain connected between the two platforms; a set of planar linkage mechanisms are arranged on end faces of the two platforms respectively, and a set of connecting mechanisms are arranged on four opposite sides of the two platforms respectively; the driving branch chain is located on a central axis of the deployable basic unit, and the driving branch chain has a cylindrical pair; the planar linkage mechanism has four identical planar links, one end of each planar link is hinged to the platform, and the four planar links are located in the plane of the platform; and the connecting mechanism is connected with two adjacent planar links in the two planar linkage mechanisms respectively. The application has good symmetry, and has many advantages such as high rigidity, light weight, high structural reliability, single-degree-of-freedom and simple driving system.

Description

Technical Field

[0001] This invention relates to a single-degree-of-freedom planar two-dimensional deployable basic unit and a large-scale deployable device. Background Technology

[0002] Deployable space mechanisms have become a research hotspot in recent years, especially large-scale deployable mechanisms with high aspect ratio, high precision, high rigidity, and lightweight. Existing deployable mechanisms are mainly used for articulated extendable arms, solid-reflector deployable antennas, frame-type deployable antennas, ring truss deployable antennas, and space capture devices. There is currently no application of large-scale deployable space mechanisms to the design of aerospace platforms for large on-orbit servicing space stations. The construction of large, multi-functional on-orbit servicing stations providing comprehensive space services, and the maintenance tasks such as on-orbit upgrades, faulty module replacements, resupply, and assembly of service satellites, rely heavily on the support and stability of large-scale deployable space platforms. Large-scale space operation platforms are composed of multiple modular deployable mechanism units connected through a network, requiring high rigidity, large load capacity, light mass, high aspect ratio, and high precision.

[0003] Existing large-scale deployable mechanisms are mainly obtained by networking deployable mechanisms such as scissor mechanisms and scissor-like mechanisms, parallelogram mechanisms, Sarrus mechanisms, Bennett mechanisms, and Bricard mechanisms. Scissor mechanisms and scissor-like mechanisms, parallelogram mechanisms, and Sarrus mechanisms have good networking capabilities, but their load-bearing capacity and stiffness are relatively low in vertical and end-face mechanisms. Over-constrained mechanisms such as Bennett and Bricard mechanisms, due to their over-constraints, have good unfolding ratios and load-bearing capacities; however, the over-constraints require strict mechanism characteristics, making manufacturing difficult and hindering large-scale networking design, easily leading to jamming. Existing large-scale deployable mechanisms are multi-degree-of-freedom, multi-output, multi-coupled mechanisms with a huge number of links, complex link connections, and significant kinematic redundancy, making them prone to jamming, deformation, and failure. Most components are rigid, making them susceptible to collision damage and vibration. The structural and kinematic asymmetry of the basic unit mechanisms makes it difficult to guarantee the configuration relationship of the entire mechanism during deployment. Any problem (drive failure, linkage interference, mechanism anomalies, etc.) can prevent the spacecraft mechanism from completing the folding and unfolding actions.

[0004] Chinese patent document 202111392173.9 discloses a type of spatially deployable basic unit and a spatially deployable polygonal prism mechanism constructed therefrom. The basic unit consists of two spatially symmetrical 7R mechanisms and a planar connecting mechanism; the planar connecting mechanism is a parallelogram mechanism composed of four rotating pairs with parallel rotation axes; the spatially deployable polygonal prism mechanism is composed of this basic unit, which has simple kinematics and good interchangeability.

[0005] Chinese patent document 202111393184.9 discloses a truss telescopic mechanism and a planar deployable truss array, wherein the spatial deployable basic unit is composed of two spatially symmetrical 7R mechanisms and a planar connection mechanism; and multiple modular units are connected to form a single-degree-of-freedom truss telescopic arm mechanism and a planar deployable truss array.

[0006] Chinese patent document 202111393233.9 discloses a ring-shaped truss-type spatial deployable mechanism. The mechanism consists of multiple spatially deployable basic units, each of which is composed of two spatially symmetrical 7R mechanisms and a planar connecting mechanism. This ring-shaped truss-type spatial deployable mechanism has good kinematic symmetry, deployment performance, stiffness performance, and bending and torsional resistance.

[0007] The main shortcomings of existing large-scale deployable mechanisms in space are as follows: First, the design of the drive pairs is crucial for large-scale deployable mechanisms. The type and placement of the drive pairs are key to ensuring smooth deployment, and a reasonable drive pair design is the cornerstone of efficient and uniform force transmission. The existing technologies do not address this issue. Second, the design of the networking method is lacking. The existing technologies do not utilize the structural characteristics of the mechanism for networking, while a reasonable and effective networking design is essential to ensure geometric coordination and synchronous deployment between modules. Summary of the Invention

[0008] In view of the many shortcomings of the existing technology, the main purpose of this invention is to provide a single-degree-of-freedom planar two-dimensional deployable basic unit and a large-scale deployable device.

[0009] To achieve the above-mentioned main objectives, the first aspect of the present invention provides a single-degree-of-freedom planar two-dimensional deployable basic unit. The deployable basic unit is a symmetrical quadrangular prism multi-closed-loop mechanism, which includes two platforms arranged in parallel and a drive chain connecting the two platforms. A set of planar linkage mechanisms is provided on the end faces of the two platforms respectively, and a set of connecting mechanisms is provided on the four opposite sides of the two platforms respectively.

[0010] The drive chain is located on the central axis of the deployable basic unit, and the drive chain has a cylindrical joint so that the two platforms can move and rotate relative to each other.

[0011] The planar linkage mechanism has four identical planar links, one end of which is hinged to the platform, and all four planar links are located in the plane of the platform.

[0012] The connecting mechanism is connected to two adjacent planar links in the two planar connecting mechanisms respectively; when the two platforms approach each other, the connecting mechanism folds synchronously, the four planar links in the planar link mechanism rotate and unfold, and the two platforms generate relative rotation around the first direction; when the two platforms separate in opposite directions, the connecting mechanism unfolds synchronously, the four planar links in the planar link mechanism rotate and fold, and the two platforms generate relative rotation in opposite directions around the first direction.

[0013] As a specific embodiment of the present invention, it also includes a driving mechanism; the cylindrical pair has a degree of freedom of movement and a degree of freedom of rotation, and the driving mechanism is used to drive the driving chain to move or rotate.

[0014] Furthermore, the drive branch has a first circular rod and a second circular rod, which are nested together to form a cylindrical pair.

[0015] In one specific embodiment of the present invention, four planar connecting rods are arranged radially around the platform.

[0016] In one specific embodiment of the present invention, the connecting mechanism is a scissor mechanism, which is a 5R mechanism, having two identical scissor bars that are hinged together at their midpoints.

[0017] Furthermore, the end of the scissor bar is provided with a connecting seat, and the scissor bar and the connecting seat are hinged through a revolute joint R1, and the planar connecting rod and the connecting seat are hinged through a revolute joint R2; wherein, the axes of the revolute joints R1 and R2 are perpendicular; the revolute joints R1 in adjacent connecting mechanisms are perpendicular.

[0018] A second aspect of the present invention provides a large-scale deployable device formed by connecting single-degree-of-freedom planar two-dimensional deployable basic units as described above.

[0019] As a specific embodiment of the present invention, adjacent single-degree-of-freedom planar two-dimensional unfoldable basic units share a set of connecting mechanisms.

[0020] The present invention has the following beneficial effects:

[0021] The deployable basic unit in this invention is a multi-closed-loop mechanism, which improves the overall stiffness and load-bearing capacity of the structure. The deployable basic unit adopts a symmetrical structure, with the drive pair arranged at the center, which helps improve the uniformity of the driving force transmission throughout the structure. Each deployable basic unit has a single degree of freedom in its deployment motion, making drive control simpler and more efficient. The large-scale deployable device in this invention is also completely symmetrical and has only one degree of freedom. Multiple deployable basic units connected in a network can achieve synchronous deployment and folding motions in the plane, thus eliminating the need for a synchronization mechanism system. This improves the reliability of the deployment and folding motions of the large-scale deployable device, while also ensuring simpler kinematics, dynamics, and control, resulting in greater stiffness and load-bearing capacity.

[0022] This invention has good symmetry and many advantages such as high rigidity, lightweight, high structural reliability, single degree of freedom, and simple drive system. It can be used as a space platform in large space service stations to provide support, positioning and fixation for satellites to be serviced.

[0023] To more clearly illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0024] Figure 1 This is a structural diagram of the deployable basic unit of the present invention;

[0025] Figure 2 This is a diagram illustrating the unfolding process of the unfoldable basic unit of the present invention;

[0026] Figure 3 This is a schematic diagram of the network of the large-scale deployable device of the present invention;

[0027] Figure 4 This is a structural diagram of the large-scale deployable device of the present invention in its deployed state;

[0028] Figure 5 This is a structural diagram of the connector in this invention;

[0029] Figure 6 This is another structural diagram of the connector in this invention;

[0030] Figure 7 This is a structural diagram of the large-scale unfoldable device of the present invention in its folded state. Detailed Implementation

[0031] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0032] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0033] This invention provides a single-degree-of-freedom planar two-dimensional unfoldable basic unit, specifically a symmetrical quadrangular prism multi-closed-loop mechanism, such as... Figure 1-2 As shown, it has two end faces, top and bottom, and four opposite sides, front, back, left and right; the deployable basic unit includes two parallel platforms 10, a drive chain 20, a planar linkage mechanism 30, and a connecting mechanism 40.

[0034] A drive chain 20 connects the two platforms 10; specifically, the drive chain 20 is located on the central axis of the deployable basic unit, and the drive chain 20 has a cylindrical joint C, meaning that the drive chain 20 can rotate and move, so that the two platforms can move and rotate relative to each other; preferably, please continue reading Figure 1 The drive chain 20 has a first circular rod 21 and a second circular rod 22, which are fixedly connected to two platforms 10 respectively; wherein the first circular rod 21 and the second circular rod 22 are nested together to form a cylindrical pair C.

[0035] Please continue reading. Figure 1 The planar linkage mechanism 30 has four identical planar links 31, and the platform 10 has four circumferentially evenly distributed hinge portions 11. One end of each planar link 31 is hinged to a hinge portion 11 of the platform 10, and all four planar links 31 are located in the plane of the platform 10. Specifically, the rotation axes of the four hinge points (O1, O2, O3, O4) where the four planar links 31 are hinged to the four hinge portions 11 are parallel to each other, which makes the planar linkage mechanism 30 have excellent foldability and single degree of freedom characteristics. Compared with spatially over-constrained deployable single-ring mechanisms, this planar linkage mechanism 30 will not experience jamming and can be smoothly deployed. Other spatially foldable mechanisms are difficult to drive and are hard to apply in practice.

[0036] Furthermore, the four planar connecting rods 31 are arranged radially around the platform 10, and can rotate, unfold, and fold around the platform 10.

[0037] The connecting mechanism 40 is connected to two adjacent planar connecting rods 31 of the two planar connecting mechanisms 40 respectively; there are four connecting mechanisms 40, which are located on the front, back, left, and right sides respectively; the connecting mechanism 40 is specifically a scissor mechanism, which is a 5R mechanism. Please refer to [reference needed]. Figure 1 The connecting mechanism 40 has two identical scissor bars 41, which are hinged together at the middle.

[0038] The end of the scissor bar 41 is provided with a connecting seat 42a. The scissor bar 41 and the connecting seat 42a are hinged together by a rotating joint R1. The planar connecting rod 31 and the connecting seat 42a are hinged together by a rotating joint R2. The axes of the rotating joints R1 and R2 are perpendicular. The rotating joints R1 in the adjacent connecting mechanisms 40 are perpendicular to each other.

[0039] like Figure 2 As shown, when the two platforms 10 approach each other, the two scissor arms 41 in the scissor mechanism fold, and the four planar links 31 in the planar linkage mechanism 30 rotate and unfold, causing the two platforms 10 to rotate relative to each other about the first direction (i.e., clockwise rotation about the up and down direction); when the two platforms 10 separate in opposite directions, the two scissor arms 41 in the scissor mechanism unfold, and the four planar links 31 in the planar linkage mechanism 30 rotate and fold, causing the two platforms 10 to rotate relative to each other about the opposite direction of the first direction (i.e., counterclockwise rotation about the up and down direction).

[0040] The deployable basic unit in this embodiment of the invention is a multi-closed-loop mechanism composed of rotating pairs with parallel rotation axes. In the scissor mechanism, the rotation axes of the rotating pairs are all parallel to each other, and in the planar connection mechanism 40, the rotation axes of the rotating pairs are also parallel to each other. Therefore, the deployable basic unit provides couple constraints. Compared to branch structures that provide force constraints, because a couple is a couple quantity, the mechanism providing couple constraints does not need to strictly guarantee the position and direction of the force axis as strictly as force constraints do. This is beneficial for manufacturing and assembly, thereby indirectly improving the deployability of the deployable basic unit. Simultaneously, the entire deployable basic unit is a multi-closed-loop mechanism, which is beneficial for improving stiffness and load-bearing capacity.

[0041] The embodiments of the present invention also include a driving mechanism (not shown in the figure). The cylindrical joint has a prismatic joint and a revolute joint. The driving mechanism is used to drive the driving chain 20 to move, that is, to drive the unfolding and folding of the unfoldable basic unit using the prismatic joint as the driving joint. In other embodiments, the unfolding and folding of the unfoldable basic unit can also be driven by the revolute joint. The entire unfoldable basic unit itself is a completely symmetrical mechanism. The driving joint is a prismatic joint, and the driving joint is arranged at the central axis of the entire unfoldable basic unit. This is beneficial to improving the uniformity of the driving force transmission of the entire unfoldable basic unit, so that the driving force is evenly distributed to each mechanism. This is beneficial to single-degree-of-freedom unfolding and folding motion, making the control structure very simple, and the unfolding and folding process more stable and reliable.

[0042] like Figure 3-4 As shown in Figure 7, in this embodiment of the invention, multiple deployable basic units are networked together as module unit A to form a large-scale deployable device. Among them, adjacent single-degree-of-freedom planar two-dimensional deployable basic units share a set of connecting mechanisms 40 to remove the connecting mechanisms 40 with the same motion of each deployable basic unit, thereby reducing the overall structure and achieving the requirement of lightweight. At the same time, this networking form ensures the geometric coordination conditions and synchronous deployment conditions between deployable basic units.

[0043] Furthermore, when the deployable basic units located inside the large-scale deployable device are networked together, methods such as... Figure 5 The connector 42b shown is... Figure 5 The connector 42b shown specifically adopts Figure 1 The diagram shows four connectors 42a prefabricated as a single unit; when the deployable basic units located outside the large-scale deployable device are networked together, the following method is used: Figure 6 The connecting seat 42c shown; the deployable basic unit located at the corner of the large-scale deployable device continues to use... Figure 1 The structure of connector 42a is shown in the figure.

[0044] In this embodiment of the invention, multiple deployable basic units are networked together to form a large-scale deployable device. The networked large-scale deployable device is also completely symmetrical and has only one degree of freedom, enabling synchronous unfolding and folding movements within a plane. Figure 4 , Figure 7 As shown; therefore, the large-scale deployable device in this embodiment of the invention does not require a synchronous mechanism system, which is beneficial to improving the reliability of the overall structure's unfolding and folding movements, and the kinematics, dynamics, and control of the overall structure are very simple. At the same time, since the large-scale deployable device is also a multi-closed-loop network structure, it has greater stiffness and load-bearing capacity.

[0045] The large-scale deployable device in this embodiment of the invention can be used on aerospace platforms without strictly ensuring over-constrained geometric relationships and complexity, thereby reducing the difficulty of processing, manufacturing and assembly, and indirectly enabling the overall structure to achieve reliable deployment and folding movements after large-scale networking.

[0046] While the present invention has been disclosed above with reference to specific embodiments, these embodiments are not intended to limit the scope of the invention. Any person skilled in the art can make variations / modifications without departing from the scope of the invention; all equivalent variations / modifications made in accordance with the present invention should be covered by the protection scope of the present invention.

Claims

1. A single degree of freedom planar two-dimensional deployable base unit, characterized by, The deployable basic unit is a symmetrical quadrangular prism multi-closed-loop mechanism, which includes two parallel platforms connected by a drive chain; a set of planar linkage mechanisms are provided on the end faces of the two platforms respectively, and a set of connecting mechanisms are provided on the four opposite sides of the two platforms respectively. The drive chain is located on the central axis of the deployable basic unit, and the drive chain has a cylindrical joint so that the two platforms can move and rotate relative to each other. The planar linkage mechanism has four identical planar links, one end of each planar link is hinged to the platform, and all four planar links are located in the plane of the platform. The connecting mechanism is connected to two adjacent planar links in the two planar linkage mechanisms respectively; when the two platforms approach each other, the connecting mechanism folds synchronously, the four planar links in the planar linkage mechanism rotate and unfold, and the two platforms generate relative rotation around the first direction; When the two platforms separate in opposite directions, the connecting mechanism unfolds synchronously, the four planar links in the planar linkage mechanism rotate and fold, and the two platforms generate relative rotation in opposite directions around the first direction.

2. The single degree of freedom planar two-dimensional deployable base unit of claim 1, wherein: It also includes a drive mechanism; the cylindrical pair has a degree of freedom of movement and a degree of freedom of rotation, and the drive mechanism is used to drive the drive chain to move or rotate.

3. The single-degree-of-freedom planar two-dimensional unfoldable basic unit as described in claim 2, characterized in that: The drive branch has a first circular rod and a second circular rod, which are nested together to form the cylindrical pair.

4. The single-degree-of-freedom planar two-dimensional unfoldable basic unit as described in claim 1, characterized in that: The four planar connecting rods are arranged radially around the platform.

5. The single-degree-of-freedom planar two-dimensional unfoldable basic unit as described in claim 1, characterized in that: The connecting mechanism is a scissor mechanism, which is a 5R mechanism, having two identical scissor bars that are hinged together at their midpoints.

6. The single-degree-of-freedom planar two-dimensional unfoldable basic unit as described in claim 5, characterized in that: The scissor bar is provided with a connecting seat at its end. The scissor bar and the connecting seat are hinged together by a revolute joint R1. The planar connecting rod is hinged together with the connecting seat by a revolute joint R2. The axes of the revolute joints R1 and R2 are perpendicular to each other. The revolute joints R1 in adjacent connecting mechanisms are perpendicular to each other.

7. A large-scale deployable device formed by networking multiple single-degree-of-freedom planar two-dimensional deployable basic units as described in any one of claims 1-6.

8. The large-scale deployable device as described in claim 7, characterized in that: Adjacent single-degree-of-freedom planar two-dimensional unfoldable basic units share a set of connection mechanisms.

Images