A rope-driven deployable truss module for on-orbit assembly

Abstract

This invention discloses a rope-driven deployment truss module for on-orbit assembly, belonging to the field of space folding mechanism technology. It addresses the limitations of large-scale development of space folding mechanisms and the volume constraints of transport vehicles. The truss mechanism of this invention includes several folding units, with adjacent folding units arranged front-to-back and connected by revolute joints. Two ropes originate from the same vertex of the outermost folding unit, connecting the rods in each folding unit in series, and finally reaching opposite vertices. One end of each rope is connected to a power element, and the other end is fixed to the opposite vertices. The folding and deployment of the truss are achieved by controlling the telescopic rods through the ropes.

Description

Technical Field

[0001] This invention belongs to the field of space folding mechanism technology, and particularly relates to a rope-driven truss module for on-orbit assembly. Background Technology

[0002] A space folding / deploying mechanism is a new type of aerospace equipment with folding and deployment capabilities, developed to better meet the trend of larger spacecraft structures. Due to the volume limitations of launch vehicles, the space folding / deploying mechanism is in a folded and retracted state during launch, and gradually unfolds and locks after entering orbit according to control commands, serving a series of functions such as support and positioning, energy harvesting, and signal transmission. Currently, research in the field of space folding / deploying mechanisms includes extendable arms, solar panels, and space deployable antennas, which are widely used in mobile communications, space science, military reconnaissance, navigation, and remote sensing. It has high academic value, engineering needs, and application prospects, and has become one of the forefront and hot topics of research in the international aerospace community. Summary of the Invention

[0003] This invention provides a rope-driven deployment truss module for on-orbit assembly, solving the problems of the increasing size of spacecraft structures and the limitations of launch vehicle volume.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A rope-driven deployment truss module for on-orbit assembly includes several folding units. Adjacent folding units are arranged one after the other and connected by a revolute joint. Two ropes start from the same vertex of the outermost folding unit, connect the rods in each folding unit in series, and finally reach the opposite vertices. One end of each rope is connected to a power element, and the other end is fixed to the opposite vertices. The folding and deployment of the truss are achieved by controlling the telescopic rods through the ropes.

[0006] In the structure described above, a reset structure is provided between adjacent folding units; adjacent folding units share one surface;

[0007] The folding unit is a cubic structure composed of connecting rods, which are connected by a revolute joint. Telescopic rods are installed at the diagonal positions of the two sides of each folding unit. Telescopic rods are also installed at the diagonal positions of the end faces of the two outermost folding units. The telescopic rods are composed of a thick telescopic rod, a thin telescopic rod, and a sleeve sliding joint. A locking mechanism is provided at the node of each cubic structure of the folding unit, and a timing mechanism is provided at the node connecting the telescopic rods to the cubic structure of each folding unit.

[0008] The formulas for calculating the length and unfolding ratio of the truss are as follows:

[0009] Before expansion: L=(3+2n)d

[0010] After expansion: L = nl

[0011] The expansion ratio is: β = (3 + 2n)d / nl

[0012] Where L is the total length of the robotic arm (the total distance from the starting unit to the ending unit); n is the number of units; d is the diameter of the link; l is the length of a folding unit after unfolding; its theoretical minimum unfolding ratio (at least two units are a module) is 8.75%, which decreases as the number of units increases.

[0013] Beneficial effects: This invention provides a rope-driven deployment truss module for on-orbit assembly, which has the following advantages compared with the prior art:

[0014] (1) Compared with fixed trusses, the truss mechanism of the present invention can reduce the space ratio and increase the space utilization rate. Its theoretical minimum folding ratio (at least two units are a module) is 8.75%, which decreases as the number of units increases.

[0015] (2) Compared with pneumatic deployment structures, the present invention has a higher strength level through rope control;

[0016] (3) The current special material shape memory alloy unfolded structure has fatigue characteristics and high requirements for environmental conditions. With the current level of technology, there is a lack of sufficient experimental data, making it difficult to ensure reliability and the research cost is high. In contrast, the structure of the present invention is simple, stable and reliable, requires fewer iterations, and most of the experimental data can be obtained in the laboratory environment and simulation iteration, which reduces costs and increases reliability in practical applications.

[0017] (4) The timing mechanism of the present invention makes the deployment more controllable;

[0018] (5) The modular design of this invention makes the application of trusses more widespread. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the truss mechanism in its deployed state in an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the truss mechanism in its folded state in an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the rope connection in the truss mechanism in an embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of the thick and thin telescopic rods in the truss mechanism of an embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of the crossbar structure in the truss mechanism of this invention.

[0024] Figure 6 This is a schematic diagram of the side rod structure in the truss mechanism in an embodiment of the present invention;

[0025] Figure 7 This is a schematic diagram of the end thick and thin telescopic rods in the truss mechanism in an embodiment of the present invention;

[0026] Figure 8 This is a schematic diagram of a revolute joint structure with telescopic rods in a truss mechanism according to an embodiment of the present invention.

[0027] Figure 9 This is a schematic diagram of a revolute joint structure without telescopic rods in a truss mechanism according to an embodiment of the present invention;

[0028] Figure 10 This is a schematic diagram of the exploded structure of the timing mechanism in the truss mechanism in an embodiment of the present invention;

[0029] Figure 11 This is a schematic diagram of the assembly and installation of the male and female heads at the beginning and end vertical members of the truss mechanism in an embodiment of the present invention;

[0030] Figure 12 This is a schematic diagram of the male and female ends of the truss mechanism in an embodiment of the present invention;

[0031] In the diagram, 1a-1d are end vertical bars, 2a-2j are thick telescopic bars, 3a-3j are thin telescopic bars, 4a-4l are side bars, 5a-5h are vertical bars, 6a-6b are end thick telescopic bars, 7a-7b are end thin telescopic bars, 8a-8t are horizontal bars, and 9 is a pin. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments:

[0033] like Figure 1 As shown, taking five folding units as an example, a rope-driven deployment truss module for on-orbit assembly includes five folding units.

[0034] The leftmost folding unit consists of end vertical bars 1a-1b, side bars 4a, 4b, 4k, 4l, vertical bars 5a, 5h, horizontal bars 8a, 8j, 8t, 8k, end thick telescopic bar 6a, end thin telescopic bar 7a, thick telescopic bars 2a, 2j, and thin telescopic bars 3a, 3j; the end vertical bars 1a-1b, side bars 4a, 4b, 4k, 4l, vertical bars 5a, 5h, and horizontal bars 8a, 8j, 8t, 8k form a cube structure, as shown below. Figure 7 As shown, the thicker telescopic rod 6a and the thinner telescopic rod 7a at the end are connected by a sleeve sliding joint to form an end telescopic structure installed at the diagonal position on the left side, as shown. Figure 4As shown, the thick telescopic rod 2a and the thin telescopic rod 3a, the thick telescopic rod 2j and the thin telescopic rod 3j are respectively connected by a sleeve moving pair to form a side telescopic structure, which is installed on the diagonal positions of both sides of the folding unit, and the installation direction is the same.

[0035] The rightmost folding unit consists of end vertical rods 1c-1d, side rods 4e, 4f, 4g, 4h, vertical rods 5d, 5e, horizontal rods 8e, 8f, 8o, 8p, end thick telescopic rod 6b, end thin telescopic rod 7b, thick telescopic rods 2e, 2f, and thin telescopic rods 3e, 3f. The end vertical rods 1c-1d, side rods 4e, 4f, 4g, 4h, vertical rods 5d, 5e, and horizontal rods 8e, 8f, 8o, 8p form a cube structure. The end thick telescopic rod 6b and the end thin telescopic rod 7b are connected by a sleeve sliding joint to form an end telescopic structure installed at the diagonal position of the right side. The thick telescopic rod 2e and the thin telescopic rod 3e, and the thick telescopic rod 2f and the thin telescopic rod 3f are connected by sleeve sliding joints to form side telescopic structures installed at the diagonal positions of both sides of the folding unit, and the installation direction is the same.

[0036] The three middle folding units do not have end telescopic structures. The rest of the structure is the same as the left and right side folding units. The side telescopic structures of the folding units from left to right are connected end to end in sequence.

[0037] like Figure 3 As shown, two ropes originate from the same vertex of the outermost folding unit and connect the rods in each folding unit respectively. Figure 3 The two routes (one for medium depth and one for shallow depth) are the routes of two ropes, and finally reach the opposite corner. One end of each rope is connected to the power element, and the other end is fixed to the opposite corner. The folding and unfolding of the truss is achieved by controlling the telescopic rod through the ropes.

[0038] like Figure 8 and Figure 9 As shown, adjacent folding units are arranged front to back and connected by a revolute joint, and the rods are also connected by a revolute joint; the allowable rotation angle is 90°.

[0039] Each folding unit cube structure has a locking mechanism at its nodes. The locking mechanism is a common spring pin locking mechanism, which means that after the component is in place, the pin aligns with the locking hole and the spring automatically releases and locks, depending on the actual situation.

[0040] like Figure 10As shown, each folding unit cube structure has a timing mechanism at the node connecting the telescopic rod. The timing mechanism includes a pin and a spring (the spring is installed in a hole, not shown in the figure). A pin slot is made on the rotating shaft of the thick and thin telescopic rod rotating joint. The pin and spring are inserted. In the initial state, the pin locks the thin telescopic rod, locking the unit where the thin telescopic rod is located. At the same time as the thick telescopic rod of the previous unit is in place, the slot at the rotating joint is in place. Under the action of the spring force, the pin slides into the slot of the thick telescopic rod rotating joint, opening the slot of the thin telescopic rod rotating joint, and the unit where the thin telescopic rod is located opens.

[0041] like Figure 11 and Figure 12 As shown, male and female connectors (elastic structures, which can be purchased separately, mainly based on market standards) are installed at the beginning and end vertical members of the truss for assembly, which facilitates modular installation after unfolding. The male and female connectors are plug-in connections.

[0042] The formulas for calculating the length and unfolding ratio of the above truss mechanism are as follows:

[0043] Before expansion: L=(3+2n)d

[0044] After expansion: L = nl

[0045] The expansion ratio is: β = (3 + 2n)d / nl

[0046] Where L is the total length of the robotic arm; n is the number of units, which is 5 in this embodiment; d is the diameter of the link; l is the length of a folding unit after unfolding; its theoretical minimum unfolding ratio (minimum two units to form a module) is 8.75%, which decreases as the number of units increases.

[0047] like Figure 3 As shown, point A is the rope lead-out point, connected to the servo motor. Before deployment, the vertical rod at point A is fixed to the base. When driven by the rope, the outermost unit where the fixed vertical rod is located unfolds under the contraction of the telescopic rod. After unfolding into a cube, the locking mechanism locks it, and the timing mechanism unlocks the unfolding of the next module. The locking mechanism consists of spring pins distributed on each rotating joint. When the rotating joint rotates to the position, the spring pins push out and lock the slots, automatically locking. The timing mechanism consists of a vertical rod, a spring (in the pin hole), a pin, a thick telescopic rod, and a thin telescopic rod. There are pin slots at the rotating joints of the thick and thin telescopic rods. Holes are drilled on the rotating shaft, and pins and springs are inserted. In the initial state, the pins lock the thin telescopic rod, locking the unit where the thin telescopic rod is located. At the same time as the thick telescopic rod of the previous unit is in place, the slot at the rotating joint is in place. Under the action of the spring force, the pin slides into the slot of the rotating joint of the thick telescopic rod, opening the slot of the rotating joint of the thin telescopic rod, and the unit where the thin telescopic rod is located opens.

[0048] The above are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A cable-driven deployment truss module for on-orbit assembly, characterized in that, The truss comprises several folding units, with adjacent units arranged one after the other and connected by a revolute joint. Two ropes originate from the same vertex of the outermost folding unit, connecting the rods in each folding unit in series, and finally reaching the opposite diagonal vertex. One end of each rope is connected to a power element, and the other end is fixed to the opposite diagonal vertex. The folding and unfolding of the truss are achieved by controlling the telescopic rods through the ropes. Each folding unit's cubic structure has a timing mechanism at the node connecting the telescopic rods. The timing mechanism includes a pin and a spring. Pin slots are provided on the rotating shafts of the revolute joints of the thick and thin telescopic rods. When the pin and spring are inserted, initially, the pin locks the thin telescopic rod, locking the unit containing the thin telescopic rod. Simultaneously with the thick telescopic rod of the previous unit reaching its position, the slot at the revolute joint also reaches its position. Under the action of the spring force, the pin slides into the slot at the revolute joint of the thick telescopic rod, opening the slot at the revolute joint of the thin telescopic rod, thus opening the unit containing the thin telescopic rod.

2. The cable-driven deployment truss module for on-orbit assembly according to claim 1, characterized in that, The folding unit is a cubic structure composed of connecting rods, which are connected by a revolute joint.

3. The cable-driven deployment truss module for on-orbit assembly according to claim 1 or 2, characterized in that, Telescopic rods are installed on the two diagonal positions of each folding unit; the telescopic rods on the same side of adjacent folding units are connected end to end.

4. The cable-driven deployment truss module for on-orbit assembly according to claim 3, characterized in that, Telescopic rods are installed at the diagonal positions of the end faces of the two outermost folding units.

5. The cable-driven deployment truss module for on-orbit assembly according to claim 4, characterized in that, The telescopic rod consists of a thick telescopic rod, a thin telescopic rod, and a sleeve sliding pair.

6. The cable-driven deployment truss module for on-orbit assembly according to claim 1 or 2, characterized in that, Each folded unit cube structure has a locking mechanism at its nodes.

7. The cable-driven deployment truss module for on-orbit assembly according to claim 1 or 2, characterized in that, Male and female connectors for assembly are installed at the beginning and end vertical members of the truss to facilitate modular installation after unfolding.

8. The cable-driven deployment truss module for on-orbit assembly according to claim 1 or 2, characterized in that, The formulas for calculating the truss length and unfolding ratio are as follows: Before expansion: L = (3 + 2n)d After expansion: L=nl The expansion ratio is: β = (3 + 2n)d / nl Where L is the total distance from the starting unit to the ending unit; n is the number of units; d is the diameter of the link; and l is the length of a folding unit after it is unfolded.

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