Structure for attaching a device to a craft, such as a nanosatellite

Abstract

The invention relates to a structure for attaching a device to a craft. The structure comprises a first base (10) intended to be attached to the craft, which base comprises a planar attachment plate (11) and two struts (12, 13) which are symmetrical relative to a plane (P) perpendicular to the plate. The structure also has a second base (20) which is identical to the first base (10) and: rotated 90° relative to the first base and relative to a first axis (y) perpendicular to the plate and flipped 180° relative to the first base and relative to a second axis (x) perpendicular to the plane of symmetry. Each strut of each base has chamfers at lateral ends to allow sliding between the first and second bases, thereby allowing the device to be deployed when it is attached to one of the bases.

Description

[0001] Title: Structure for attaching equipment to a device, such as a nanosatellite

[0002] This description relates to a structure for fixing equipment intended to be fixed to a machine, for example a mobile machine such as a drone, or a satellite, or even a terrestrial machine.

[0003] The aforementioned equipment may include, for example, a sensor such as a camera or other, or one or more solar panels to power a storage battery of the vehicle, or a communication antenna, or others. The fixing structure may be applied advantageously, but not limited to, fixing on a satellite gravitating in low Earth orbit (or "LEO"). A specification has been established for such an application and more particularly for "nanosatellites". This specification is called "CubeSat" hereinafter and created to reduce the launch costs of very small satellites (weighing less than 20 kg) and thus allow small and medium-sized companies or public institutions such as universities to develop and place their own spacecraft in orbit. This standard aims to guarantee the suitability of satellites with the main payload of the launchers that put them into orbit.

[0004] The CubeSat specifications require a cubic base unit (1U) of 100 x 100 x 100 mm at launch (1 liter of internal volume) for a weight not exceeding 1.33 kg. A 1U cubic base unit may have a mechanical structure to which equipment is attached for the functionality of the satellite (for example, photovoltaic panels and / or a battery for its energy, an antenna for its radio communication, sensors for its flight control, and / or to acquire measurement data, etc.). One or more base units (which may provide different functionalities) may be assembled to attach to a flying vehicle and thus form satellites of 1U, 2U, 3U, 6U, 12U. Depending on the geographic area, system complexity and ease of access to launchers, the cost of a 1U cube (including launch) remains significant, mainly due to the fact that each unit is developed each time for a single application.

[0005] Indeed, the versatility of a CubeSat structure remains to be exploited for the integration of the payload (whether technical for the operation of the satellite, scientific to carry sensors in particular, or even commercial).

[0006] Furthermore, known CubeSat elements for equipment attachment usually have a single-piece, or assembled, structure, with each structure being specific to the needs of the nanosatellite in question. Such an approach significantly reduces the ease of assembly and the post-assembly checks required for satellite certification.

[0007] A promising design has been proposed in document EP3339188, and provides a frame from a single-piece structural part.

[0008] However, the mechanical structure presented in this document remains complex and a solution is being sought to produce CubeSat structures:

[0009] - in large quantities (on an industrial scale), with low production costs,

[0010] - ensuring rapid assembly, and

[0011] - with versatility capabilities to accommodate different types of equipment.

[0012] This description improves the situation.

[0013] For this purpose, it proposes a structure for fixing at least one piece of equipment intended to be fixed to a machine. The structure comprises a first base intended to be fixed to the machine, and comprising a flat fixing base and two symmetrical spacers relative to a plane perpendicular to the base.

[0014] In particular, the structure further comprises a second base, identical to the first base and:

[0015] - rotated 90° relative to the first base and relative to a first axis perpendicular to the base, and

[0016] - turned 180° relative to the first base and relative to a second axis perpendicular to the plane of symmetry.

[0017] Each spacer of each base has chamfers at the side ends to allow sliding between the first and second bases, allowing the equipment to be deployed when attached to one of the bases.

[0018] Thus, at a minimum, the structure includes bases that fit into each other and are identical, which makes it possible to produce such elements of this structure on a large scale and to assemble the structure simply and quickly.

[0019] In one embodiment, the structure may further comprise plates covering at least each spacer and each fixed to the outside of a spacer.

[0020] Thus, in this embodiment at least, the structure can be completely closed when it is compact as shown in Figure 2. Each spacer being covered by a plate, the structure is closed and can protect (in this compact form) equipment housed inside the structure (a camera, or any sensor). When the structure is deployed, the equipment is then uncovered, visible and operational to acquire data for example in the case of a sensor.

[0021] In such an embodiment, the structure may also include plates fixed to the edges of the bases, not occupied by a spacer, to give the structure a general shape (of a closed parallelepiped) comprising at least two straight blocks sliding into each other.

[0022] For example, the plates can be fixed to the base plates to leave their ends free, away from the bases, thus facilitating the sliding of one paving stone into the other.

[0023] Furthermore, the bases themselves, on the internal faces of the paving stones, can slide relative to each other thanks to the aforementioned chamfers, provided on the lateral edges of the spacers.

[0024] The equipment can then be fixed to one of the bases by means of at least one of the plates, the plates being configured to accommodate means for fixing equipment.

[0025] In one embodiment, it may be provided that first and second plates facing each other and belonging to two respective straight blocks cooperate with each other by a sliding mechanism to ensure the sliding of one block into the other.

[0026] For example, the slide mechanism can be formed by a finger:

[0027] - carried by the first plate at an end distant from the base on which the first plate is fixed, and

[0028] - engaged in a long groove in the second plate.

[0029] Furthermore, to deploy one base relative to the other, the structure may further comprise a spring means.

[0030] For example, the spring means may comprise a blade, inflected, semi-rigid and having opposite ends and fixed to the respective bases of the first and second bases (for example by screwing, snap-fastening, welding or otherwise, on each of the base bases).

[0031] To maintain the spring means in compression before deployment of the equipment, the structure may include a heat-breakable wire. The section of this wire (by heat input for example) can then release the spring means to lengthen. In one embodiment of the structure, the base and the spacers of each base are made from a single piece, advantageously by 3D printing. Such an embodiment makes it possible to limit the material and production costs by using lightweight but strong materials.

[0032] In one embodiment of the structure, each strut comprises a cross-brace shape for reinforcing the structure.

[0033] In one embodiment, the structure is configured to be fixed to a mobile machine, the aforementioned equipment being intended to be embarked on this mobile machine. For example, the structure can be compact (with the two blocks tucked into each other) during the maneuvers of the mobile machine, then deployed when the machine is at its destination, for example in orbit for a satellite.

[0034] This description also relates to a base comprising a plinth and two spacers, of a structure according to the present invention.

[0035] Indeed, such a base shape is advantageous insofar as just two identical bases can already allow the manufacture of a 1U cube.

[0036] This description also relates to a machine comprising a structure according to the present invention, this structure being fixed to the machine by one of the aforementioned bases.

[0037] Other characteristics and advantages of the structure will appear on reading the detailed description below and on examining the attached drawings, in which:

[0038] Figure 1 illustrates a first base with a base 11 and two symmetrical spacers 12 and 13,

[0039] Figure 2 illustrates the assembly of the first base 10 and a second base 20, identical to the first base but turned in particular by 90°,

[0040] Figure 3 illustrates the assembly of these bases with protective plates, forming two straight blocks sliding into each other,

[0041] Figure 4 illustrates a detail of the mechanism for sliding one block into the other, comprising in the example illustrated, a finger D sliding in an elongated groove RL, Figure 5 illustrates an embodiment for a spring means MR allowing the deployment of one block relative to the other when this spring means is released from compression support,

[0042] Figure 6 illustrates an exemplary embodiment in which the spacers of a base also comprise rails for fixing electronic cards. The subject of the present description relates to a mechanical structure which is composed of two identical elements which are assembled by fitting onto a slide. Each basic element (hereinafter called “base” for fixing equipment or machinery, and bearing the reference 10 in Figure 1) comprises three faces:

[0043] - two identical “sides” (hereinafter called “spacers” and referenced 12 and 13 in figure 1), and

[0044] - a base (hereinafter called “base” and referenced 11 in figure 1).

[0045] The machine, for example, can be fixed to the base 10 by the base IL. As illustrated in Figure 1, the fixing base 11 is flat, and the two spacers 12 and 13 are symmetrical with respect to a plane P perpendicular to the base 11.

[0046] As now illustrated in Figure 2, the structure further comprises a second base 20, identical to the first base 10 and:

[0047] - rotated 90° relative to the first base 10 and relative to a first axis y perpendicular to the base, and

[0048] - turned 180° relative to the first base 10 and relative to a second axis x perpendicular to the plane of symmetry P.

[0049] Like the first base 10, the second base 20 comprises a base 21, and two symmetrical spacers 22, 23. Each spacer 12, 13, 22, 23 is reinforced by a cross-brace shape, visible in figures 1 and 2. The uprights of the spacers (at the ends of their cross-brace) form the edges of a rectangular parallelepiped which may be a cube, with the bases 11 and 21, as shown in figure 2.

[0050] In terms of dimensions, each base 11, 21 may have a surface area of ​​80x80 mm with a large opening allowing good communication between two separate CubeSat units. The uprights at the ends of the crosspieces are beveled to each form a chamfer acting as rails for the interlocking of the base which closes the cube as illustrated in Figure 2. Thus, each spacer of each base has chamfers (referenced C1, C2 in Figure 1), at lateral ends to allow sliding between the first and second bases 10, 20, which makes it possible to deploy (or uncover) the equipment when it is fixed to one of the bases.

[0051] Indeed, the equipment can be deployed when it is fixed to the second base 20, or alternatively be fixed to the first base 10 (the same one which is fixed to the machine) but be hidden by the second base 20, which uncovers it (for example like a photovoltaic panel) after sliding deploying one of the bases relative to the other. Such deployment can typically be carried out after maneuvers to start moving the machine, so as not to hinder these maneuvers. For example, for a flying machine (drone or other), the structure can be compact when the machine is on the ground before taking off and then be deployed during the flight.

[0052] As illustrated in Figure 5, the structure may include one or more MR springs (e.g., shape memory springs) to slide one base relative to the other when the spring is released. The MR springs may be attached to respective bases via screw holes provided in the plane of each base as seen in Figure 5.

[0053] Referring now to Figure 3, the bases can be closed by plates (referenced P12, P13, P22, P23 in Figure 3) covering at least each spacer 12, 13, 22, 23 and each fixed on the outside of the spacer. Thus, such plates can protect on-board equipment such as smart cards or batteries, or others. Electronic cards can in fact be slid inside a base for example by a slide / fixing mechanism and thus remain protected by the aforementioned plates. Such an embodiment is illustrated by way of example in Figure 6: the spacers 11 and 12 of a base 10 can additionally comprise means for fixing equipment such as here slides for accommodating electronic cards.More generally, equipment can be fixed to the structure via a plate or directly to a base, possibly to a spacer of such a base since, in addition, holes which can be used for this fixing are already provided in the spacers.

[0054] In one embodiment, at least part of the plates of the internal base (P22, P23, P24, P25) can be replaced by photovoltaic panels of the same dimensions, and thus the deployment of one base relative to the other makes it possible to uncover one or more photovoltaic panels to be operational, typically in flight. Of course, such panels can also be fixed on these plates.

[0055] In addition, the structure comprises in particular plates referenced P14, P15, P24, P25 in figure 3 and fixed on the edges of the bases which are not occupied by a spacer, to completely close the cubes and give the structure a general shape of two straight paving stones sliding into each other.

[0056] The equipment can then be fixed to one of the bases by means of at least one of the plates, the plates having holes configured to accommodate means for fixing equipment. For example, the equipment can include one or more photovoltaic panels for a power supply to the mobile machine, or sensors such as a camera or other. It will thus be understood that the deployment of one base relative to the other makes it possible to free up surfaces of the small right block, sliding in the large right block, and thus leave such equipment free to perform its function (capture solar radiation or an optical field, for example).

[0057] As visible in Figure 3, the plates P12 to P15 of the outer block (at the bottom of Figure 3) are only fixed on the base 11 of the lower base 10. The plates P12 to P15 are left free, however, in the upper part (distal to the base 11). A clearance is thus left allowing the inner block (of the upper base 20) to slide into the outer block (of the lower base 10). Thus, in the non-deployed position, the inner block can slide into the outer block to form the base of a 1U cube. As illustrated in Figure 4, this interlocking can be ensured by a sliding mechanism of a finger D arranged in each plate of the inner block (P22 to P25) in a slide RL arranged in each plate of the outer block (P12 to P15).

[0058] The holes in a base for attaching a plate may be, for example, a few millimeters in diameter. In the case where several cubes are connected to each other, the bases of the respective cubes can be attached to each other via holes made in each plane of a base (as visible on the top part of figures 2 and 3).

[0059] The mechanism of sliding one block into the other is now described in more detail, with reference to figure 3.

[0060] First and second plates (pair P12, P25 of Figure 3; pair P14, P22 of Figure 3; pair P15, P23 of Figure 3; pair P13, P24 of Figure 3) facing each other and belonging to two respective straight blocks cooperate with each other by a slide mechanism for sliding. As can be seen in particular in Figure 4, this slide mechanism is formed by a finger D:

[0061] - carried by the first plate at an end distant from the base on which the first plate is fixed, and

[0062] - engaged in a long, straight groove RL which the second plate has.

[0063] Referring now to Figure 5, the spring means MR for deploying one of the bases relative to the other is described in more detail.

[0064] As illustrated in the example of Figure 5, the spring means MR comprises a blade, inflected, semi-rigid and having opposite ends and fixed to the respective bases of the first and second bases.

[0065] A heat-breakable wire can be provided to retain the spring means in compression before deployment of the equipment. Thus, a section of this wire can be controlled electronically (by releasing heat from a resistor for example), thus freeing the spring means to extend.

[0066] Alternatively, a shape memory material can be provided that extends or retracts by applying a suitable control voltage, or a motor (jack, worm screw, or cable) can be provided to extend one base relative to the other.

[0067] Typically, shape memory materials are widely used in the aerospace field. Current refinement of their design and use allows offering a wide range of possible candidates for realizing the MR spring medium.

[0068] Thus, the structure within the meaning of the present description has two identical parts (the bases), one turned over relative to the other by 90°. These parts (as well as the plates which cover them in Figure 3) can be produced in large quantities and at low cost, for example by additional manufacturing or “3D printing”. For example, superplastics having properties close to those of metal for a mass half the size can be used to make the base and the spacers of each base, without screws or welding, because in fact, as can be seen in Figures 1 and 2, the base and the spacers of each base can be made from a single piece.

[0069] The entire structure can thus be additively printed using almost all the materials available for this purpose, particularly for aeronautical applications. Furthermore, additive manufacturing allows for material savings. Typically, in comparison with the structure presented in the document EP3339188 introduced above, the loss of material must be of the order of 90%, whereas with 3D printing of the structure within the meaning of the present description, this loss can be considered zero.

[0070] Furthermore, the materials generally used for additive manufacturing (superplastics such as PEEK for example) offer:

[0071] - resistance to shock and deformation,

[0072] - low manufacturing cost,

[0073] - low weight.

[0074] More generally, the structure within the meaning of this description offers:

[0075] - A simplification of its manufacturing process by limiting the number of different parts to be produced,

[0076] - Integration of all the cube's internal and external equipment (solar panels, electronic cards, antennas, measuring instruments, etc.), offering almost absolute versatility, - Easy connection of the cubes to each other (by the bases or by the plates),

[0077] - Possible deployment of elements with a volume greater than the cube once the satellite is in orbit.

[0078] Indeed, a usual limitation of the CubeSat lies in the authorized volume, which is quite small, which certainly allows the production of spacecraft at low costs, but also prevents the sending into orbit of certain devices requiring larger volumes such as solar panels or certain sensors for specific scientific experiments. The surface area of ​​the solar panels, for example, necessarily reduced, is one of the main limiting factors of CubeSats. This is why it is advantageous to plan for deployment of the cubes once in orbit. The structure within the meaning of the present application provides a mechanical solution allowing, for example, the doubling of the surface area of ​​solar panels for a single cube.

Claims

Claims 1. Structure for fixing at least one piece of equipment intended to be fixed to a machine, comprising a first base (10) intended to be fixed to the machine, and comprising a fixing base, plane (11), and two spacers (12, 13) symmetrical relative to a plane (P) perpendicular to the base, Characterized in that it further comprises a second base (20) identical to the first base (10) and: - rotated 90° relative to the first base and relative to a first axis (y) perpendicular to the base, and - turned 180° relative to the first base and relative to a second axis (x) perpendicular to the plane of symmetry, and in that each spacer of each base has chamfers (Cl, C2) at lateral ends to allow sliding between the first and second bases, which allows the equipment to be deployed when it is fixed to one of the bases.

2. Structure according to claim 1, characterized in that it further comprises plates (P12, P13, P22, P23) covering at least each spacer (12, 13; 22, 23) and each fixed to the outside of a spacer.

3. Structure according to claim 2, characterized in that it further comprises plates (P14, P15, P24, P25) fixed on the edges of the bases, not occupied by a spacer, to give the structure a general shape comprising at least two straight blocks sliding into each other.

4. Structure according to one of claims 2 and 3, characterized in that the equipment is fixed to one of the bases by means of at least one of the plates, the plates being configured to accommodate means for fixing equipment.

5. Structure according to claim 3, characterized in that first and second plates (P12, P25; P14, P22; P15, P23; P13, P24) facing each other and belonging two respective straight blocks cooperate with each other by a slide mechanism for sliding.

6. Structure according to claim 5, characterized in that the slide mechanism is formed by a finger: - carried by the first plate at an end distant from the base on which the first plate is fixed, and - engaged in a long groove (RL) which the second plate has.

7. Structure according to one of the preceding claims, characterized in that it further comprises a spring means (MR) for deploying one of the bases relative to the other.

8. Structure according to claim 7, characterized in that the spring means (MR) comprises a blade, inflected, semi-rigid and having opposite ends and fixed to the respective bases of the first and second bases.

9. Structure according to one of claims 7 and 8, characterized in that it comprises a heat-breakable wire to retain the spring means in compression before deployment of the equipment, a section of said wire releasing the spring means to lengthen.

10. Structure according to one of the preceding claims, characterized in that the base and the spacers of each base are made from a single piece.

11. Structure according to claim 10, characterized in that the base and the spacers of each base are produced by 3D printing.

12. Structure according to one of the preceding claims, characterized in that each spacer comprises a cross-shaped reinforcement of the structure.

13. Structure according to one of the preceding claims, characterized in that it is configured to be fixed on a mobile machine, the equipment being intended to be embarked on said mobile machine.

14. Base comprising a base and two spacers, of a structure according to one of the preceding claims.

15. Machine comprising a structure according to one of claims 1 to 13, said structure being fixed to the machine by one of said bases.

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