Passive (SELF) expansion parallelogram articulated lattice mast

Abstract

To provide a self-expandable mast for supporting a payload.SOLUTION: A mast has an upper long body, a lower long body, and a hinge linkage that form a series of movable parallelograms which are movable so as to fold and expand. The mast has a spring having at least one spring and one truss associated with each parallelogram, and a truss. The spring can operate so as to expand the mast from a folded position to an expanded position. Each truss can operate so as to obliquely traverse the associated parallelogram and receive tensile force when the mast is expanded to a final position. In other embodiments, a motor can be used in place of the spring.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This patent application relates to passively deployable devices, and more particularly to masts for such devices. [Background technology]

[0002] Various masts, booms, arms, etc. are used in different applications to hold payloads, such as equipment, in or above space. For example, in communications applications, a "mast" is a generally vertical structure that supports an antenna at a height sufficient to transmit or receive radio waves. As another example, a "boom" may be used to bring a microphone closer to the source of the sound to be amplified.

[0003] As used herein, "mast" is used collectively to include booms, arms, and any similar elongated rigid structure, typically having a lattice or tubular structure. It is assumed that the mast is capable of providing suitable support for a payload. The payload may be a "tip mass" at the end of the mast, or may have mass distributed along all or part of the mast.

[0004] Self-deployable masts and their payloads are sometimes used in space or in unsafe environments, or for other applications where a human operator cannot be readily available. These mast / payload systems are often housed as compact modules on the move and deployed once to a desired location.

[0005] U.S. Patent Application 18 / 100472 describes a solar panel array for use in space having a truss backing for supporting the solar panels, the truss backing being a mast that is integrated with the solar array to form a self-deployable structure.

[0006] Fully actuated and controlled (non-passive) deployments typically use motors, which add power and mechanical risk to the deployment. Often the uncertainty of some passively deployed systems results in increased risk, which can drive requirements for controlled deployments that use additional motors. These add weight, complexity, and overall cost to the system.

[0007] Some self-deploying systems are referred to as "passive" deployment systems because the deployment of the device is actively initiated but then completed without external control. At the desired time, one or more actuators are used to initiate the deployment. Many systems that rely on passive deployment have mechanically indeterminate deployment, which can lead to an increased risk of damage to the system or poor operation.

[0008] A more complete understanding of the present embodiments and their advantages can be obtained by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features and in which: [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a mast supporting the device in a deployed state. [Diagram 2] FIG. 2 is a side view of the mast in a folded (undeployed) state. [Diagram 3] FIG. 3 is a top view of the mast in an undeployed state. [Figure 4] Figure 4 shows the mast during deployment. [Diagram 5] FIG. 5 is a second view of the mast during deployment, at a time subsequent to that of FIG. [Figure 6] FIG. 6 is a detailed view of the valley of FIG. [Figure 7] FIG. 7 is a detailed view of the mountain of FIG. [Figure 8] FIG. 8 shows a portion of the mast fully deployed. [Figure 9]FIG. 9 shows an example of a hinge link mechanism. [Figure 10] FIG. 10 illustrates a mast with an alternative embodiment of the spring and hinge linkage. [Figure 11] FIG. 11 shows an embodiment of a mast in which the hinge linkage is x-shaped rather than v-shaped. [Figure 12] FIG. 12 shows an embodiment of a mast in which deployment is achieved using a motor rather than a spring. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The following description is directed to a passively deployable mast, typically used to support a payload vertically or horizontally. The mast comprises a series of parallelogram joints that deploy deterministically.

[0011] Figure 1 is a perspective view of a mast 10 according to the present invention. In Figure 1, the mast 10 is in its unfolded (unfolded) position.

[0012] In the example of FIG. 1, the mast 10 is deployed from a base station at one end. At the other end it supports a payload 11. The payload 11 is represented as a "black box" and is a tip mass, i.e., attached to the end of the mast 10. In other applications, the payload may be located anywhere on the mast or distributed along the length of the mast. The payload is often a piece of equipment. It may be any device, for example, a camera or other inspection or data collection device. As another example, the payload 11 may be a tool, a robot, or something that is remotely mechanically operated.

[0013] The base station on which the mast 10 is deployed is not explicitly shown. The base station may be fixed or mobile. The mast 10 may be deployed in a gravity or non-gravity environment.

[0014] The sizing of the mast 10 is typically determined by the size of the payload 11 it will support. A payload with a larger mass may require a shorter reach and a heavier mast, while a payload of a smaller mass may allow a longer reach and a lighter mast design. Various electrical connections or other wiring or cabling from the payload 11 to the base station may be accomplished conventionally and are not shown.

[0015] An exemplary application of the mast 10 is as a mast system launched into space. To fit the mast system (mast 10 and associated payload 11) into a launcher, the mast system is folded and stowed into a launcher. Once the launcher has reached a desired orbit, the mast system is deployed. The deployment occurs such that the system goes from a stowed state to an operational (deployed) state. A feature of the invention described herein is that the deployment is "synchronized," meaning that the entire mast 10 deploys at the same time, rather than in a series of actuations.

[0016] Thus, the mast 10 provides a means for deploying the payload 11 to a desired location on or off the base station and for supporting the payload 11 after deployment. The mast 10 provides the desired stiffness to support the payload 11 at the desired reach.

[0017] When the mast 10 is deployed as in Figure 1, the mast forms a rigid structure along its length. After deployment, the mast 10 becomes a truss structure that includes a series of repeating sections S, also called "bays" in mast applications. In the example of Figure 1, the mast 10 has four sections. Each section has two rigid elongated bodies 21 and 22 with hinge linkages 23 separating the sections. Each section also has an associated spring 24 and diagonal 25.

[0018] 1, each section S has one upper elongated body 21, one lower elongated body 22, two springs 24, and two diagonals 25. The elongated bodies 21 and 22 are flat and planar and made from a single piece of rigid material, but may be tubular or have some other flat rigid structure.

[0019] In this deployed state, springs 24 assist in deployment by providing a constant spring force. Truss 25 is tensioned to give the mast 10 its desired stiffness over its entire length. The structure and operation of springs 24 and truss 25 are described further below.

[0020] The springs 24 and trusses 25 are mirrored from left to right. In other embodiments, one or more of these components may be reduced to a single component. There is not necessarily a one-to-one relationship between the number of springs and the number of trusses.

[0021] Hinge linkages 23 connect the segment sections S. Geometrically, between the hinge linkages 23, the upper and lower elongated bodies of each segment form a series of parallelograms. The hinge linkages 23 allow the mast 10 to fold like an accordion in its undeployed state. When the mast 10 is deployed, the hinge linkages 23 allow the interior shape of each parallelogram to "unfold," i.e., open up and become less flat and more rectangular. The hinge linkages 23 can be configured with a variety of mechanisms, some examples of which are described below.

[0022] In the embodiment of Figure 1, each section has two springs 24 and two diagonals 25, one spring and truss on one side of the elongated body and the other spring and truss on the other side of the elongated body. On each side, a truss 25 is attached to a corner of the lower elongated body 21 and an opposing corner of the upper elongated body 22. In other words, the truss 25 extends diagonally across the side of a parallelogram.

[0023] The springs 24 are similarly mounted at an angle, but may be mounted offset from the corners. The springs 24 are on one side and the other of their associated portions, but may be positioned in other ways so long as they function to open the mast 10 as described herein.

[0024] The diagonals 25 are configured to run "bottom to top" in the first section, then "top to bottom" in the next section, so that the trusses 25 run in the same diagonal direction in each section, but the diagonal direction alternates from section to section.

[0025] In Figure 1, the diagonal 25 is under tension during deployment due to the opposing force of the spring 24. The deployment process will now be described.

[0026] Figure 2 is a side view of the mast 10 in a folded (undeployed) state. As shown, the hinge linkage 23 allows the mast 10 to fold for storage, resulting in a compact package. The springs 24 and trusses 25 are not shown. In this view, the parallelograms formed by the sections are in a "flat" or "closed" state, as opposed to the "open" rectangular shape they have after deployment.

[0027] The sections of the mast 10 are folded in an alternating accordion-like fashion. Typically, the mast sections are the same length, resulting in a series of symmetrical folds or "zigzags".

[0028] 3 is a bottom view of the mast 10 in an undeployed state. The springs 24 are implemented as "buckled plates," e.g., narrow strips of thin, flexible material. An example of a suitable material is fiberglass rod. The plates are buckled (preloaded) in each section so that when released they press against hinge linkages 23, as described below.

[0029] Other possible embodiments of the spring 24 are a torsion spring, a torsion rod, or a compression spring. A variety of passive mechanisms can be used to apply a constant spring force during deployment.

[0030] Although not shown, various damping mechanisms may be desirable to control deployment, although a single damper at the interface may be sufficient.

[0031] The truss 25 is not shown in FIG. 3 but is in a slack (untensioned) state when the mast 10 is not deployed. The truss 25 may be implemented with flexible strips, cables, wires, cords, or rods, or other flexible elongated material that can be tensioned from a slack state in response to the force of the springs 24 during deployment. This tension is applied diagonally across the parallelogram formed by the upper and lower sections and linkages. A flexible strip or carbon cord, such as a plate that is axially stiff and shorter than the spring plate, may be advantageous.

[0032] 4 shows the mast 10 during deployment. The hinge linkage 23 enables this folding and deployment of the mast 10. Specifically, the hinge linkage 23 enables the parallelograms (formed by the upper and lower elongated bodies) to change shape from their closed, folded shape to a more open, rectangular shape as the mast deploys.

[0033] Of particular interest in Figure 4 is the action of spring 24 and truss 25. Mast 10 is actuated such that spring 24 is released, pushing mast 10 away from its attachment point to the base station (satellite or otherwise). The elastic energy stored in spring 24 during folding provides the deployment force. In this state, diagonal 25 is still slack. Hinge linkage 23 keeps mast 10 straight and consistent at its angles during deployment.

[0034] Figure 5 is another view of mid-deployment of the mast 10 during deployment, some time after Figure 4. At this stage of deployment, the springs 24 continue their deployment force. The truss diagonals 25 are still slack. The hinge linkages 23 keep the sections of the mast 10 in line, keeping the deployment synchronized and deterministic.

[0035] Figures 6 and 7 show detailed views of the valleys (Figure 6) and peaks (Figure 7) of Figure 5. The hinge linkage 23 is described in more detail below.

[0036] 8 shows a portion of the mast 10 fully deployed. Springs 24 continue to apply force to each section of the mast 10. Diagonals 25 are now under tension as a result of the force of springs 24. Slop in linkage 23 allows diagonals 25 to control the end positions of the mast 10, creating a tensioned mast 10.

[0037] The hinge linkages 23 are only "active" during deployment in the sense that their operational role ceases once the solar array is deployed. During deployment, the hinge linkages 23 provide uniform deployment, but are structurally invisible once the mast is deployed.

[0038] Figure 9 shows an example of a hinge linkage 23, where the mast 10 is in its deployed state and the diagonals 25 are tensioned as described above. The elongates 21 and 22 of each section are fully spaced apart and the parallelogram they form opens from flat to more rectangular. The hinge linkage 23 opens in a "v" shape in this deployed state of the mast 10.

[0039] In the embodiment of FIG. 9, each hinge link mechanism 23 has a first hinge 91 connecting two adjacent elongated bodies of adjacent parts of the mast 10. A second hinge 92 connects the other two adjacent elongated bodies. Here, hinge 91 connects the two lower elongated bodies 22 and hinge 92 connects the two upper elongated bodies 21. However, as shown in the previous figures, the hinge link mechanisms 23 alternate their orientation between the sections, such that hinges 91 and 92 alternately connect upper and lower elongated bodies. This configuration allows the mast 10 to be folded as described above.

[0040] Hinge 91 is a pivoting hinge that is slightly offset to allow the two elongated bodies to fold onto each other. Hinge 92 is also an offset hinge (with a larger offset than hinge 91) that allows the two elongated bodies to move apart when the mast 10 is folded, so that the two elongated bodies fold on the outside of the other two elongated bodies in the adjacent section. This flattening and accordion folding of the elongated bodies is shown above in connection with Figures 2 and 3.

[0041] The hinge linkage 23 further includes two pairs of linkage arms 93. The linkage arms 93 form the "v" shape of the hinge linkage 23. All of the linkage arms 93 are attached at one end to the hinge 91 and extend from the apex of the v shape of the hinge linkage 23. One pair of arms 93 extend from the hinge 91 to one of the opposing elongated bodies and the other pair of arms 93 extend to the other of the opposing elongated bodies, all extending to connect to their respective elongated bodies at a point near the offset hinge 92.

[0042] Referring again to the figure above, the hinge linkages 23 alternate between sections of the mast 10 and are oriented so that their v-shapes are one above the other.

[0043] 10 shows a mast 10 having another embodiment of a spring and hinge linkage. The spring 124 and / or hinge linkage 123 may be used with the mast 10 described above.

[0044] Similar to the embodiment of FIG. 9, each hinge link mechanism 123 has a first hinge 111 connecting two adjacent elongated bodies of adjacent sections of the mast 10. A second hinge 112 connects the other two adjacent elongated bodies. Here, hinge 111 connects two lower elongated bodies 22 and hinge 112 connects two upper elongated bodies 22. Similar to the hinge link mechanism 23, the hinge link mechanism 123 alternates in orientation between sections such that hinges 111 and 112 alternately connect upper and lower elongated bodies.

[0045] Hinge 111 is a pivot hinge and is slightly offset to allow its two elongated bodies to fold onto each other. Hinge 112 is also an offset hinge which allows the two elongated bodies to fold on the outside of the two other elongated bodies of the adjacent section. This configuration allows the mast 10 to accordion fold as described above.

[0046] The hinge linkage 103 is again v-shaped. Its link arm 116 extends from the hinge 112 and upper elongated body 21 to the lower elongated body 22, the connection point of which is offset from the hinge 111.

[0047] Like hinge linkage 23, hinge linkage 103 is oriented such that the v-shape alternates up and down between the sections of the mast. However, in this embodiment, the end of upper elongated body 21 attached to link arm 116 folds into the v-shape of hinge linkage 123. This folding direction is shown by the arrows in FIG.

[0048] Each section has two springs 124 attached between the elongated bodies 21 and 22, one on each side of the elongated bodies. These springs 124 are attached closer to the midpoint of the elongated bodies rather than at their diagonal ends. As with all other embodiments, the springs 24 function to push the upper and lower elongated bodies 21 and 22 apart during deployment, tensioning the diagonal 125.

[0049] As with the other embodiments, the trusses 125 are attached diagonally from hinges 111 in one section to hinges 111 in the next section. The alternating diagonal pattern of the trusses 125 is maintained by the alternating orientation of the hinge linkages 123.

[0050] Figure 11 shows an embodiment of the mast 10 in which the hinge connections 133 are x-shaped rather than v-shaped. Linking arms 134 cross between the elongated bodies. The ends of the linking arms 134 are offset from the hinges between the elongated bodies at both the top and bottom of the mast.

[0051] As with the other embodiments, one hinge 135 of the hinge linkage 133 allows the two attached elongated bodies to fold. The other hinge 136 of the hinge linkage 133 is an offset hinge, allowing the two attached elongated bodies to fold relative to each other, as described above. The truss 135 is attached to the opposing diagonal hinges 125.

[0052] In short, the mast 10 enables a mechanically deterministic passively deployed support structure. Deployment is internally synchronized regardless of the number of sections used in the mast. The mast is easily scalable in size, geometry, payload mass, amount of solar panels, root attachments, and deployment forces.

[0053] Figure 12 shows an embodiment of a mast in which deployment is accomplished using motors rather than springs. This embodiment is similar to the embodiment above in the sense that once deployment is initiated, it is self-actuated and does not require external control from a base station (such as a spacecraft) during deployment.

[0054] Specifically, the mast 100 has a motor 101 mounted on the hinge linkage 23. In the example of FIG. 12, the motor 101 rotates the hinge linkage 23 relative to the upper elongated body 21, thus actuating the two sections. Alternatively or additionally, a motor can be used to rotate the lower elongated body 22. Alternatively, a motor can be located on every hinge linkage 23. In general, it is expected that deployment can be achieved using the motor 101 to rotate at least every other hinge linkage 23.

[0055] As in the embodiment described above, an initial release or trigger is used to initiate deployment, but thereafter the mast self-deploys. For example, the motor 101 may be powered by a latch circuit that runs until a mechanism hits a limit switch and then shuts off the power. Switch logic can be used to drive the motor 101, again without requiring a base station to help control the deployment. The motor 101 may be powered by any conventional means used to power an electric motor.

[0056] During deployment, the motor 101 provides a torque to the hinge linkage 123. Similar to the spring described above, the motor 101 opens the hinge linkage 123, creating tension in the diagonal 25.

Claims

1. 1. A passively deployable mast, comprising: A series of lower elongated bodies; A series of upper elongated bodies; a hinge link mechanism operable to attach the lower elongated body to the upper elongated body of an adjacent section such that the pair of lower and upper elongated bodies form a series of parallelograms operable to fold and unfold in an accordion-like manner; at least one spring associated with each parallelogram portion; at least one diagonal associated with each parallelogram portion; Equipped with the spring is operable to deploy the mast from a folded position to a deployed position; each diagonal is operable to be tensioned diagonally across its associated parallelogram by action of said spring when said mast is deployed to its final deployed position.

2. 2. The mast of claim 1, wherein the spring is a plate that can be placed under load by being buckled.

3. The mast of claim 1 , wherein the spring is a torsion spring, a torsion rod, or a compression spring.

4. The mast of claim 1 , wherein the diagonal is implemented with a flexible wire, cable, cord, or rod.

5. 2. The mast of claim 1, wherein the upper and lower elongated bodies of each section have first and second sides, at least one spring, and a diagonal on each side.

6. Each hinge link mechanism includes a first hinge connecting two adjacent elongated members, a second hinge connecting the other two adjacent elongated members, and a pair of link mechanism arms; The mast of claim 1 , wherein the second hinge is an offset hinge.

7. The folding mast A series of lower elongated bodies; A series of upper elongated bodies; a hinge link mechanism operable to attach the lower elongated body to the upper elongated body of an adjacent section such that the pair of lower and upper elongated bodies form a series of parallelograms operable to fold and unfold in an accordion-like manner; at least one spring associated with each parallelogram portion; at least one diagonal associated with each parallelogram portion; Equipped with a spring operable to deploy the mast from a folded position to a deployed position, the springs operable to tension the mast diagonally across its associated parallelogram portion by action of the spring when the mast is deployed to a final deployed position.

8. The method of claim 7 further comprising damping steps of the movement.

9. 8. The method of claim 7, wherein the spring is a plate that can be placed under load by being buckled.

10. The deployment method of claim 7 , wherein the spring is a torsion spring, a torsion rod, or a compression spring.

11. The method of claim 7 , wherein the diagonals are implemented with flexible wires, cables, cords, or rods.

12. 8. The method of claim 7, wherein each of the pair of lower and upper elongate bodies has a first side and a second side, at least one spring, and a diagonal on each side.

13. 1. A motor deployable mast, comprising: A series of lower elongated bodies; A series of upper elongated bodies; a hinge link mechanism operable to attach the lower elongated body to the upper elongated body of an adjacent section such that the pair of lower and upper elongated bodies form a series of parallelograms operable to fold and unfold in an accordion-like manner; a number of motors operable to provide torque to the hinge linkage, at least one motor associated with each of two or more parallelograms; at least one diagonal associated with each parallelogram portion; Equipped with a plurality of said motors operable to deploy said mast from a folded position to a deployed position; each diagonal is operable to tension a diagonal across its associated parallelogram by action of said springs when said mast is deployed to a final deployed position.

14. 14. The mast of claim 13, wherein the diagonal is implemented with a flexible wire, cable, cord, or rod.

15. 14. The mast of claim 13, wherein the upper and lower elongated bodies of each section have first and second sides, at least one spring, and a diagonal on each side.

16. Each hinge link mechanism includes a first hinge connecting two adjacent elongated members, a second hinge connecting the other two adjacent elongated members, and a pair of link mechanism arms; The mast of claim 13, wherein the second hinge is an offset hinge.

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