Abstract
Self-deploying reflector array architectures include stacked multiple panels attached to a central panel by sets of heat actuated flexible hinges on their non-functional sides create surface of revolution, cylindrical and flat reflector arrays in accordance with panel curvature. Robotic in-space assembly of multiple smaller arrays allows for creation of reflector array of 10 or more meters to support S-band and above RF (2 GHz) transmission.
Claims
1. An antenna reflector array having at least a stowed position and a deployed position, the array comprising: multiple panels and a central panel, each of the multiple and central panels including a functional side and a non-functional side, wherein in the stowed position, the multiple and central panels are in a compact configuration; at least one heat actuated flexible hinge formed of a shape memory composite (SMC) substrate, each of the at least one flexible hinge being connected at a first end thereof to a non-functional side of one of the multiple panels and at a second end thereof to the non-functional side of the central panel, the at least one heat actuated flexible hinge being controllable between a first shape and a second shape; and further wherein, when each of the at least one heat actuated flexible hinge changes from the first shape to the second shape, the multiple panels connected thereto are moved from a first position to a second position.
2. The antenna reflector array of claim 1, wherein each of the at least one flexible hinge includes a controllable heater for providing heat to a heat actuated flexible hinge to actuate the heat actuated flexible hinge between the first and second shapes.
3. The antenna reflector array of claim 1, wherein each of the heat actuated flexible hinges is tubular.
4. The antenna reflector array of claim 1, wherein each of the multiple panels and the central panel are a rigid construction.
5. The antenna reflector array of claim 1, wherein at least one of the heat actuated flexible hinges includes a hinge having a single hinge point and remaining the of heat actuated flexible hinges include hinges having dual hinge points.
6. The antenna reflector array of claim 1, wherein the compact configuration is a stacked configuration, wherein the functional side of the central panel faces away from the non-functional sides of the multiple panels.
7. The antenna reflector array of claim 6, wherein the functional side of each of the multiple and central panels is curved; and wherein when in the stacked configuration the curved functional side of the central panel faces an opposite direction from the curved functional sides of the multiple panels and when in the deployed position the curved functional side of the central panel faces a same direction as the curved functional sides of the multiple panels.
8. The antenna reflector array of claim 7, wherein the curved functional side of each of the multiple and central panels is a single curve; and further wherein when in the deployed position, the antenna reflector array is cylindrical.
9. The antenna reflector array of claim 7, wherein the curved functional side of each of the multiple and central panels is a double curve; and further wherein when in the deployed position the antenna reflector array is a surface of revolution such as a paraboloid.
10. The antenna reflector array of claim 6, wherein the functional side of each of the multiple and central panels is flat; and further wherein when in the deployed position the antenna reflector array is flat.
11. The antenna reflector array of claim 6, wherein when in the stacked configuration, all of the multiple panels are stacked below the central panel and deployment of the multiple panels occurs from the outermost panel in the stack to the innermost panel in the stack with respect to the central panel.
12. The antenna reflector array of claim 6, wherein when in the stacked configuration, at least one of the multiple panels is stacked above the central panel and remaining multiple panels are stacked below the central panel.
13. The antenna reflector array of claim 6, wherein when in the stacked configuration, each of the multiple panels is concentrically aligned with the central panel.
14. The antenna reflector array of claim 6, wherein when in the stacked configuration, the stack is staggered and a first edge of each of the multiple panels is offset a distance D.sub.o from a first edge of the central panel and an offset distance D.sub.o is different for each of the multiple panels.
15. The antenna reflector array of claim 14, wherein the offset distance D.sub.o for each of the multiple panels is equal to a vertical distance D.sub.v between each of the multiple panels and the central panel in the stack.
16. The antenna reflector array of claim 1, wherein when in the compact configuration, each of the multiple panels is held at an approximately 90 degree angle to the central panel by the at least one of the heat actuated flexible hinges.
Description
DETAILED DESCRIPTION
(1) It is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.
(2) FIG. 1 presents a first configuration of a seven-panel reflector array 10 in a stowed, concentrically stacked configuration. Rigid hexagonal panels one through six, P.sub.1, P.sub.2, P.sub.3, P.sub.4, P.sub.5, P.sub.6, are attached to the central panel P.sub.C, by individual sets of two composite tubular hinges H.sub.1, H.sub.2, H.sub.3, H.sub.4 (not shown), H.sub.5 (not shown), H.sub.6. Panels P.sub.1, P.sub.2, P.sub.3, P.sub.4, P.sub.5, P.sub.6 are constructed using a sandwich approach to yield a high specific stiffness construction. By way of example, the panel core can be made from carbon foam (CFOAM 30) sealed with ES-215 epoxy resin mixed with IHG hardener that is used in high temperature composite tooling or a carbon fiber reinforced plastic (CFRP) honeycomb sheet, both of which provide a low coefficient of thermal expansion (CTE) material. CFRP face sheets can be co-cured directly onto the cores and bonded in a single step using a thin EA9696 epoxy film or similar adhesive. The face sheet is a four-ply balanced and symmetric plain weave laminate. Additional details may be found in the conference manuscript to Juan M. Fernandez et al., SEGMENTED HEXAGONAL ANTENNA REFLECTOR CONCENTRICALLY STACKED USING SHAPE MEMORY COMPOSITE TUBULAR HINGES, 41.sup.st ESA Antenna Workshop on Large Deployable Antennas, 25-28 Sep. 2023 at ESA-ESTEC in Noordwijk, The Netherlands, the contents of which is incorporated herein by reference in its entirety.
(3) In the embodiment shown in FIG. 1, all panels are double curved. Further to the configuration of FIG. 1, when in the stowed or stacked position, the central panel P.sub.C's concave, reflective side P.sub.CS.sub.1 faces awayor oppositefrom the functional, reflective sides, e.g., P.sub.6S.sub.1, of panels one through six. The non-functional, non-reflective sides of central panel P.sub.C, P.sub.CS.sub.2 and P.sub.6, P.sub.6S.sub.2 face each other. While the illustrated panel shape is hexagonal, other panels shapes are possible, such as squares or pentagons. In the deployed position, all concave, functional, reflective sides of P.sub.C, P.sub.1, P.sub.2, P.sub.3, P.sub.4, P.sub.5, P.sub.6 face the same direction to create a parabolic reflector (see FIG. 8a). In alternatives embodiments, all panels may be doubly curved to form any desired surface of revolution (spherical, paraboloid, etc.) in the deployed state, single curved to form a cylindrical surface in the deployed state, or flat to form a flat surface in the deployed state. Hinges H.sub.1, H.sub.2, H.sub.3, H.sub.4, H.sub.5, and H.sub.6 are attached to the non-functional, non-reflective sides of panels P.sub.C, P.sub.1, P.sub.2, P.sub.3, P.sub.4, P.sub.5, P.sub.6.
(4) FIGS. 2a and 2b present array 10 in different stages of the reflector deployment process. Specifically, FIG. 2a shows the first panel P.sub.1 at a first interim point of deployment, wherein the two composite hinges in set H.sub.1 mid-process of straightening. And FIG. 2b shows the first panel P.sub.1 at a second interim point of deployment, wherein the two composite hinges in set H.sub.1 are straight.
(5) Composite hinges H.sub.1, H.sub.2, H.sub.3, H.sub.4, H.sub.5, and H.sub.6 are formed from a flexible shape memory composite (SMC) substrate such as that described in co-owned U.S. patent application Ser. No. 18/605,929 and U.S. Provisional Patent Application No. 63/452,712 which are incorporated herein by reference in their entireties. Components formed from SMC can be programmed into a temporary shape through applied force and internal heating. In the programmed shape, the deformed structure is in a frozen state remaining dormant without external constraints. Upon heating once more, the substrate will return slowly (several to tens of seconds) to the original shape.
(6) Referring to FIGS. 3a, 3b, 3c and 3d, a first exemplary hinge 100 formed from SMC is originally in the tubular shape shown in FIGS. 3a, 3b and has been programmed into the temporary, frozen shape shown in FIG. 3d. Upon heat (actuating) being applied to one or more heaters (not shown) embedded within or on the surface of the hinge 100 while in its pre-programmed frozen shape (FIG. 3d), hinge 100 unfolds, passing through intermediate shapes (e.g., FIG. 3c) to its original shape (FIG. 3a, 3b). Hinge 100 is in a tube configuration, with a cutout portion 150 on diametrically opposing sides of the tube. Hinge 100 includes first and second ends E.sub.1 and E.sub.2.
(7) Similar to the first exemplary hinge 100, a second exemplary hinge 200 (FIGS. 4a, 4b, 4c) is identical to hinge 100 in all respects except hinge 200 includes two cutout portions 150, two on each diametrically opposite side, which facilitate two hinging points 205a and 205b during actuation (as compared to single hinge point 105 in hinge 100). The cutouts of exemplary hinges 100 and 200 are diametrically opposite dog bone-shapes that enable localized pinching and folding the hinge without damage. Dog bone slots are preferred over straight slots with a constant slot width to increase deployed stiffness and minimize the risk of hinge snap back and deployment anomaly. Other optimal cutout shapes are possible depending on the hinge design.
(8) As described in co-owned U.S. patent application Ser. No. 18/605,929 SMC hinges used in the present embodiments may also include on or more layers of heat spreading material to assist with distribution of applied heat, as well as sensors, such as strain and temperature sensors and a microprocessor for implementing a monitoring and feedback process.
(9) As illustrated in FIGS. 5a, 5b and 5c, at least a first hinge 100 may be used to secure panel P.sub.6 to the central panel P.sub.C. Panel P.sub.6 is stowed when the hinge is in its programmed temporary shape (FIG. 5a) and opens when the hinge is heat actuated through its one or more heaters, passing through various intermediate shapes (FIG. 5b) until panel P.sub.6 is fully unfolded when hinge 100 is at its original shape (FIG. 5c). For all other panels, P.sub.1, P.sub.2, P.sub.3, P.sub.4, P.sub.5, hinge 200 is used as these panels are farther from the central panel P.sub.c and the dual hinge points 205a, 205b are needed to complete the approximately 180-degree unfolding.
(10) In a preferred embodiment, each panel P.sub.x is connected to the central panel P.sub.C by two parallel hinges, 100a and 100b as shown in FIGS. 6a and 6b. FIG. 6a is an isometric view of the underside of FIG. 5c and shows additional features of the reflector array. More particularly, FIG. 6a shows guide rails R.sub.1 and R.sub.2 and spring 160 which facilitate closing the remaining gap G between panels P.sub.x and P.sub.C once hinge 100 has finished unfolding. FIG. 6b shows the panels with no gap therebetween. Also shown are cup 162 and cone 164 mating elements which further align and secure the panels together. While only one set of mating elements are shown in the FIGS., a second set is located on the opposite side of the hinges. Additional alignment feature pairs can be used. FIGS. 6f, 6g, 6h and 6i provide various views and features of the exemplary mating elements 162 and cone 164. In FIGS. 6h and 6i, cone 164 includes protruding cone portion 165 which includes press fit portions 166 located at approximately 120, 240 and 360 degree locations on cone portion 165. At the end of each press fit portion 166 is a clip protrusion 167 for clicking into place within a female receiver portion 168 in cup 162.
(11) FIGS. 6c, 6d and 6e provide additional views of the guide rails R.sub.1 and R.sub.2 and the hold-down release mechanism 172 located on each panel P.sub.x. Mechanism 172 fixes hinge end fittings 170a, 170b to the panel P.sub.x when held down. When released, spring 160 is triggered and the spring force (constant force spring or tension spring) act approximately along the tubular hinge axis when the hinges are deployed to close the gap G by translating the hinge end fittings 170a, 170b fixed to trolley 174 along the guide rails R.sub.1 and R.sub.2. The hold-down release mechanism 172 can take the form of, for example, a Frangibolt or a pin puller.
(12) FIG. 7 provides a top view of the reflector array midway through deployment. As shown, panels P.sub.1 and P.sub.2 are deployed and in place, panel P.sub.3 is partially deployed and panels P.sub.4, P.sub.5 and P.sub.2 are awaiting deployment, in order.
(13) FIGS. 9a and 9b show top view (FIG. 9a) of fully deployed reflector array and bottom view (FIG. 9b) of fully deployed reflector array. In FIG. 9b, note the different lengths of the pairs of hinges. The panel P.sub.1, which is furthest from the central panel P.sub.C in the stowed stack (see FIG. 1), has the longest hinges H.sub.1, with hinges decreasing in size moving up the stowed stack to shortest hinges H.sub.6 on P.sub.6. When deployed the hinges form a backbone support structure on the non-functional, non-reflective side that provides out-of-plane stiffness to the reflector assembly. Without the hinges, the seam line(s) of the assembly would behave like a hinge in itself.
(14) FIGS. 9a, 9b, 9c, 9d, 9e, 9f, 9g, 9h, 9i, 9j, 9k illustrate a second stacked configuration of a seven-panel reflector array wherein the panels are stacked in a offset or staggered configuration such that each panel directly aligns with the central panel and neighboring panels when its respective hinges are unfolded. The lateral offset between each panel in the stowed state is designed such that when the pairs of tubular SMC hinges actuate they already mate the pairs of panel edges and there is no need for a secondary mechanism to close a gap between the central and neighboring panels and the newly unfolded panel as is required in the first concentrically stacked configuration describe above with respect to FIG. 1 et seq. Accordingly, while the concentric case provides an axisymmetric stacked configuration that is more volumetrically efficient, it is a heavier and more complex configuration than the offset approach of FIG. 9a et seq. due to the need for the use of the secondary closing mechanisms. In order to achieve direct alignment of each side panel with the central panel during deployment, the offset distance D.sub.o must equal the vertical panel to panel distance D.sub.v for each panel. By way of example, FIG. 9a shows central panel P.sub.C and two side panels P.sub.x and P.sub.y. The closest panel P.sub.x, has offset distance D.sub.o=d and vertical panel to panel distance D.sub.v=b. In order for direct mating between the edge E.sub.x of panel P.sub.x and the edge E.sub.C1 of central panel P.sub.C to occur when deployed, the following must be true b=d. Similarly, for panel P.sub.y, which has offset distance D.sub.o=c and vertical panel to panel distance D.sub.v=a. In order for direct mating between the edge E.sub.y of panel P.sub.y and the edge E.sub.C2 of central panel P.sub.C to occur when deployed, the following must be true a=c.
(15) FIGS. 9b to 9k provide various views of a panel stowage sequence for a deployed offset reflector stack.
(16) FIGS. 10a, 10b, 10c and 10d illustrate how the reflectors described above are central to a scalable architecture design which uses a combination of deployable and robotic-arm in-space assembly to construct a larger reflector. Referring to FIG. 10a, the outermost side panel, e.g., P.sub.1 from stacked configurations above (furthest from the central one) will connect to the main spacecraft boom 250 having hinges 255, which is anchored from the spacecraft 400. As this side panel deploys first, the stacked reflector sub-array 10.sub.a will be displaced from the spacecraft and the rest of the side panels will deploy one at a time triggered by activate hinges, e.g., the thermally actuated SMC hinges described above, resulting in a fully deployed reflector sub-array 10.sub.a as shown in FIG. 10b.
(17) In FIG. 10c, this first deployed sub-reflector 10.sub.a can become the central reflector sub-array in a larger reflector by connecting to additional deployed reflector sub-arrays 10.sub.b, 10.sub.c, 10.sub.a, 10.sub.e, 10.sub.f, and 10.sub.g via their individual booms 260 to contact points 265 on the central reflector sub-array 10.sub.a and other robotically connected assembly plates 270 as shown in FIG. 10d. Robotic arm 280 may be used to facilitate connections and placing of assembly plates described herein.
(18) Referring to FIG. 10d, the final larger reflector 300 is the series of high-precision reflector sub-arrays 10.sub.b, 10.sub.c, 10.sub.d, 10.sub.e, 10.sub.f, and 10.sub.g, each cantilevered from a small offset boom 260 that a robotic arm attached to the spacecraft 400 uses to place and fix to the main central deployable reflector sub-array 10.sub.a already supported from the main spacecraft boom 250, as shown in FIG. 10a. To increase the number of load paths through each reflector sub-array and increase global deployed stiffness, rigid interconnect assembly plates 270 can be used. This architecture does not require a robotic arm much longer than the size of the central reflector sub-array in order to keep cost down as the system scales up since the robotic arm is one of the main cost drivers. Robotic arm 280 is not shown to scale.
(19) One skilled in the art will recognize that panel stacking configurations described above are not limited to the configurations shown. For example, FIGS. 11a, 11b and 11c illustrate alternative configurations to the panel stacking configuration of FIG. 1. In FIG. 11a, panels are stacked below (P.sub.1, P.sub.3, P.sub.5) and above (P.sub.2, P.sub.4, P.sub.6) the central panel P.sub.C. In this configuration, some panels may be deployed at the same time, e.g., P.sub.1 and P.sub.2, P.sub.3 and P.sub.4, and P.sub.5 and P.sub.6. It will be appreciated that the number of panels below and above need not be the same. In FIG. 11b, panels P.sub.1, P.sub.2, P.sub.3, P.sub.4 (not shown) need not be stacked vertically, but could be stowed around the natural sides of a cube-type satellite 300. In this configuration, hinges H.sub.1, H.sub.2, H.sub.3, H.sub.4 (not shown), need only deploy 90 degrees (versus the 180 degrees in the stacked configurations). In FIG. 11c, which is showing a top view facing central panel P.sub.C, panels P.sub.1 thru P.sub.6, are stowed around the natural sides of an hexagonal-type satellite 310. In this configuration hinges H.sub.1 thru H.sub.6 need only deploy 90 degrees.
(20) All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
(21) The use of the terms a and an and the and similar referents in the context of describing the embodiments (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms comprising, having, including, and containing are to be construed as open-ended terms (i.e., meaning including, but not limited to,) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., such as) provided herein, is intended merely to better illuminate the features of the embodiments and does not pose a limitation on the scope of the embodiments unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the embodiments.
(22) Preferred embodiments are described herein. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, these embodiments includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the embodiments unless otherwise indicated herein or otherwise clearly contradicted by context.
