Extention rod

Abstract

To provide an extension rod with high strength that is suitable for usage in a cosmic space including a lunar surface.SOLUTION: An extension rod comprises: a bistable boom that extends linearly in an extending direction in an extending form and is retained in an opened cross sectional shape in which a cross section that is orthogonal to the extending direction is curved in a circular arc shape and wound up cylindrically in a wound-up form, in which the cross section that is orthogonal to the extending direction is retained to extend linearly; and a telescopic boom constituted of a plurality of hollow cylindrical members having different diameters and has a multistage cylindrical shape in which the other cylindrical members are concentrically stored inside the cylindrical member with a maximum diameter in a stored form and end parts of the cylindrical members are connected to each other in the extended form. The telescopic boom is arranged inside the bistable boom in the extended state. The cylindrical member positioned at a tip in the extending direction of the plurality of cylindrical members constituting the telescopic boom is connected to a tip part in the extending direction of the bistable boom, and the bistable boom and the telescopic boom extend in the same direction in tandem with each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an extension rod with a bistable boom and a telescopic boom. [Background technology]

[0002] Extension rods with a deployment mechanism that can be moved from a stowed configuration to an extended configuration are used as deployment devices for solar panel (SAP) and structural materials of space structures such as antennas used in artificial satellites and lunar probes. Known extension rods include those that use a bistable boom and those that use a telescopic boom.

[0003] A bistable boom has a boom body made of a long, elastic plate material. By bending the boom body in a curved shape in the width direction (short direction) perpendicular to the extension direction (longitudinal direction), it assumes a stable extended form with an open cross-sectional shape in the cross section perpendicular to the extension direction. On the other hand, by bending the boom body while it is wound into a cylindrical shape around a central axis parallel to the width direction, it assumes a stable retracted form. In the retracted form, the elastic body curved in the width direction is stretched linearly, and an elastic restoring force acts to return it to the curved shape. When it is extended slightly in the extension direction from the retracted form, it self-extends and transitions to the extended form.

[0004] A telescopic boom is made up of multiple hollow cylindrical members of different diameters. In its retracted configuration, the largest-diameter cylindrical member houses the other multiple cylindrical members concentrically inside it. When extended, the cylindrical members are successively pulled out, starting with the smallest, to form an extended configuration in which the ends of the multiple cylindrical members are connected to form a multi-stage, long rod. Extending a telescopic boom requires a drive source to pull the internal cylindrical members out. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Utility Model Registration No. 3141015 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-130998 Summary of the Invention [Problem to be solved by the invention]

[0006] Because a bistable boom has an open cross-sectional shape in the extended configuration, it is prone to bending or curving at the open parts of the open cross-sectional shape, and there is a possibility that it may not be strong enough, particularly for lunar probe applications where gravity acts. On the other hand, because the joints between the cylindrical members of a telescopic boom are exposed to the outside when extended, there is a possibility that fine foreign matter such as sand may get into the joints and hinder the extension operation, particularly for lunar probe applications.

[0007] An object of the present invention is to provide a high-strength extension rod suitable for use in outer space, including on the lunar surface. [Means for solving the problem]

[0008] The present invention employs the following means to solve the above problems.

[0009] That is, the extension rod of the present invention is A bistable boom that can stably hold two forms, an extended form and a retracted form, in which in the extended form it extends linearly in the extension direction and is held in an open cross-sectional shape in which the cross section perpendicular to the extension direction is curved in an arc shape, and in the retracted form it is wound up cylindrically around a central axis parallel to the width direction perpendicular to the extension direction and is held in a state in which the cross section perpendicular to the extension direction is extended linearly. Stability boom and a telescopic boom comprising a plurality of hollow cylindrical members of different diameters, wherein in a stored configuration, the cylindrical member with the largest diameter has the other cylindrical members stored concentrically inside it, and in an extended configuration, the ends of the cylindrical members are connected to each other to form a multi-stage cylindrical shape; and The telescopic boom is disposed within the bistable boom in an extended configuration; The cylindrical member that is located at the tip of the extension direction in the extended form among the plurality of cylindrical members that constitute the telescopic boom is connected to the tip of the extension direction of the bistable boom, and the bistable boom and the telescopic boom are characterized in that they extend in the same direction in conjunction with each other.

[0010] With an extension rod configured in this manner, the telescopic boom is disposed inside the bistable boom, and the bistable boom and the telescopic boom extend in the same direction in unison, so even if an external force that bends or curves the bistable boom acts on the bistable boom through the open portion of the open cross-sectional shape of the bistable boom in the extended form, the bistable boom is supported by the highly strong telescopic boom disposed inside the bistable boom, preventing the bistable boom from bending during the extension operation or after reaching the extended form. Therefore, sufficient strength can be ensured even in an environment where gravity is present, such as in lunar probe applications.

[0011] Furthermore, because the telescopic boom in the extension configuration is disposed inside the bistable boom in the extension configuration, the cylindrical surface of the bistable boom covers most of the outer periphery of the telescopic boom. This reduces the exposed portion of the joints between the cylindrical members of the telescopic boom in the extension configuration, preventing sand and other small foreign objects from entering the joints. This allows the telescopic boom to be extended more reliably even in environments where foreign objects are present, such as in lunar probe applications.

[0012] The bistable boom may be connected to the cylindrical member of the telescopic boom at a circumferential center portion of an inner circumferential surface of a tip end portion in an extension direction.

[0013] When the bistable boom has both a retracted configuration and an extended configuration, the cross-sectional shape perpendicular to the extension direction becomes closer to a straight line as it approaches the retracted configuration and closer to an arc shape with a smaller radius of curvature as it moves away from the retracted configuration. Therefore, the cross-sectional shape of the tip of the bistable boom changes from a straight line to an arc shape during extension, but the position of the circumferential center within the cross-section hardly moves during extension. Therefore, the relative positional relationship within the cross-section between the circumferential center of the tip of the bistable boom and the cylindrical member at the tip of the telescopic boom remains almost constant. Therefore, by connecting the circumferential center of the tip of the bistable boom to the cylindrical member at the tip of the telescopic boom as described above, it is possible to suppress loads on the connected bistable boom and telescopic boom during extension of the extension rod.

[0014] The telescopic boom can be configured to transition to the extended configuration together with the bistable boom by the other cylindrical members stored in the cylindrical member with the largest diameter in the stored configuration being pulled out sequentially from the cylindrical member with the smallest diameter connected to the tip of the bistable boom by the extending bistable boom.

[0015] This allows the telescopic boom to be extended in conjunction with the extension of the bistable boom.

[0016] the bistable boom has a plurality of through holes spaced apart along the extension direction; a sprocket having a projection that engages with the through hole; a motor that rotates the sprocket to extend the bistable boom; It is good to have.

[0017] With this configuration, the bistable boom and the telescopic boom connected thereto can be extended by the driving force of the motor.

[0018] a housing having a housing portion that houses the bistable boom and a fixing portion to which a cylindrical member with a maximum diameter of the telescopic boom is fixed, the bistable boom is accommodated in the accommodation section in a state in which a tip end of the bistable boom is pulled out in an extension direction from a wound state by a predetermined length, The fixing portion is provided at a position spaced apart from the accommodation portion in the extension direction, The sprocket may be provided at a position between the housing portion and the fixed portion in the extension direction.

[0019] According to this configuration, the bistable boom is held in the housing with both a retracted configuration portion and an extended configuration portion coexisting, and the telescopic boom is fixed at a position away from the retracted configuration portion in the extension direction. The bistable boom is substantially flat near the retracted configuration portion. The protrusions of the sprocket engage with the through-holes of the bistable boom at this flat portion, enabling more reliable transmission of driving force from the sprocket to the bistable boom. Furthermore, since the radius of curvature of the bistable boom in the width direction decreases with increasing distance from the retracted configuration portion in the extension direction, fixing the telescopic boom at a position away from the retracted configuration portion of the bistable boom in the extension direction allows the bistable boom to cover as much of the outer circumferential surface of the telescopic boom as possible, even near the base of the extended configuration.

[0020] The above configurations may be combined as much as possible. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a high-strength extension rod suitable for use in outer space, including the surface of the moon. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 10 is a perspective view showing the extension rod of the embodiment in a stored state. [Figure 2] FIG. 1 is a perspective view showing an extension rod of an embodiment in an extended state. [Figure 3]FIG. 1 is a perspective view showing a bistable boom of an embodiment. [Figure 4] FIG. 2 is a cross-sectional view showing a bistable boom according to an embodiment. [Figure 5] FIG. 1 is a front view showing a telescopic boom according to an embodiment. [Figure 6] FIG. 2 is a perspective view showing the configuration of a housing of the extension rod of the embodiment. [Figure 7] FIG. 2 is a cross-sectional view showing the configuration of the housing of the extension rod of the embodiment. [Figure 8] FIG. 1 is a perspective view showing the distal end of the extension rod of the embodiment in a stored state. [Figure 9] FIG. 1 is a perspective view showing the distal end of an extension rod of an embodiment in an extended state. [Figure 10] FIG. 1 is a cross-sectional view showing the distal end of an extension rod according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] The following detailed description of the present invention will be given by way of example with reference to the accompanying drawings, although the dimensions, materials, shapes, relative positions, etc. of the components described in the examples are not intended to limit the scope of the present invention unless otherwise specified.

[0024] Figures 1 and 2 are perspective views of an extension rod according to an embodiment, with Figure 1 showing the extension rod in a retracted state and Figure 2 showing the extension rod in an extended state. Figures 3 and 4 are views of a bistable boom constituting the extension rod according to an embodiment, with Figure 3 being a perspective view and Figure 4 being a cross-sectional view. Figure 5 is a view of a telescopic boom constituting the extension rod according to an embodiment. Figures 6 and 7 are views showing the configuration of the housing of the extension rod according to an embodiment, with Figure 6 being a perspective view and Figure 7 being a cross-sectional view. Figures 8 and 9 are perspective views of the tip of the extension rod according to an embodiment, with Figure 8 showing the tip of the extension rod in a retracted state and Figure 9 showing the tip of the extension rod in an extended state. Figure 10 is a cross-sectional view of the tip of the extension rod according to an embodiment.

[0025] 1 and 2, the extension rod 1 has a bistable boom 10, a telescopic boom 20, and a housing 30. In the following description, the extension direction of the bistable boom 10 and the telescopic boom 20 is referred to as the X direction, the width direction perpendicular to the extension direction of the bistable boom 10 is referred to as the Y direction, and the direction perpendicular to the X direction and Y direction is referred to as the Z direction.

[0026] (bistable boom) The bistable boom 10 is composed of a long elastic member that can stably maintain two configurations: an extended configuration and a retracted configuration. Figure 3 is a perspective view showing the bistable boom 10 in a state where an extended configuration portion 14 and a retracted configuration portion 12 coexist. The portion between the retracted configuration portion 12 and the extended configuration portion 14 is called a transition portion 13.

[0027] In the extended configuration, the bistable boom 10 is entirely an extended configuration portion 14. In the extended configuration, it extends linearly in the extension direction X. FIG. 4(C) shows a cross section of the extended configuration portion 14 of the bistable boom 10 taken along section C in FIG. 3. As shown in FIG. 4(C), the cross section of the extended configuration portion 14 perpendicular to the extension direction X is curved in an arc and has an open cross-sectional shape with a portion that opens in the Z direction. The extended configuration portion 14 can also be said to have a shape in which a portion of a hollow cylinder is cut out parallel to the generatrix. In this case, the central angle corresponding to the cut-out arc in the cross section perpendicular to the extension direction X can be made smaller than 180 degrees. This gives the extended configuration portion 14 a shape that is close to a hollow cylinder.

[0028] In the retracted form, the entire bistable boom 10 becomes a retracted form portion 12. In the retracted form, the bistable boom 10 is retracted into a cylindrical shape around a central axis L parallel to a width direction Y perpendicular to the extension direction X. FIG. 4(A) shows a cross section of the retracted form portion 12 of the bistable boom 10 taken along section A in FIG. 3. As shown in FIG. 4(A), the cross section of the retracted form portion 12 perpendicular to the extension direction X has a shape that extends linearly parallel to the central axis L.

[0029] Figure 4(B) shows a cross section of the transition portion 13 of the bistable boom 10 taken along section B in Figure 3. As shown in Figure 4(B), in the transition portion 13, the cross section perpendicular to the extension direction X is curved to have a smaller radius of curvature than the retracted form portion 12 and a larger radius of curvature than the extended form portion 14. The state in which the transition portion 13 exists is mechanically unstable, and the bistable boom 10 self-extends to the extended form due to the elastic force of the elastic members that make up the bistable boom 10.

[0030] Carbon fiber reinforced plastic (CFRP) can be suitably used as the material for the bistable boom 10. CFRP has high specific rigidity and high specific strength. The bistable boom 10 made of a CFRP fiber composite material can exhibit the bistability of stably maintaining the two configurations of the extended configuration and the retracted configuration.

[0031] As shown in Figure 3, the bistable boom 10 has a plurality of through holes 11 spaced apart along the extension direction X. In the bistable boom 10 of the embodiment, the through holes 11 are They are spaced equally along X.

[0032] (telescopic boom) As shown in Fig. 5, the telescopic boom 20 is made up of a plurality of hollow cylindrical members of different diameters. Fig. 5 shows an example in which the telescopic boom 20 is made up of four cylindrical members 21, 22, 23, and 24, but this is an example for the purpose of explanation, and the number of cylindrical members constituting the telescopic boom 20 is not limited to this example. Fig. 5(A) shows the telescopic boom 20 in an extended state, and Fig. 5(B) shows the telescopic boom 20 in a stored state.

[0033] In the extended configuration, the telescopic boom 20 has a multi-stage cylindrical shape with the ends of cylindrical members connected to each other, as shown in FIG. 5(A), and in the stored configuration, as shown in FIG. 5(B), the other cylindrical members 22, 23, 24 are stored concentrically inside the cylindrical member 21 with the largest diameter.

[0034] In the connecting portion 26, a certain cylindrical member (hereinafter referred to as the first cylindrical member) and a cylindrical member (hereinafter referred to as the second cylindrical member) having the next smallest diameter after the first cylindrical member are arranged along the extension direction X, and the end of the first cylindrical member on the extension direction X side is connected to the end of the second cylindrical member on the opposite side of the extension direction X (the -X direction side). A known structure can be used to connect the ends of adjacent cylindrical members. For example, each cylindrical member has a tapered shape that slightly reduces in diameter along the extension direction X, and the first cylindrical member and the second cylindrical member are fixed in a connected state by friction or fitting between the inner circumferential surface of the first cylindrical member and the outer circumferential surface of the second cylindrical member at the connecting portion.

[0035] Although FIG. 5(B) illustrates an example in which the lengths of the cylindrical members 21 to 24 in the extension direction are equal to each other, the lengths of the cylindrical members in the extension direction may be different.

[0036] (Housing) 6 and 7, the housing 30 has a storage section 33 that stores the bistable boom 10, and a fixing section 31 to which the cylindrical member 21 with the largest diameter of the telescopic boom 20 is fixed. The bistable boom 10 is stored in the storage section 33 with the tip thereof pulled out a predetermined length in the extension direction X from the retracted form portion 12. The fixing section 31 is provided at a position separated in the extension direction X from the retracted form portion 12 of the bistable boom 10 stored in the storage section 33.

[0037] The housing 30 also has a sprocket 32 ​​having a plurality of protrusions 37 engageable with the through-holes 11 of the bistable boom 10, a rotation shaft 38 that rotatably supports the sprocket 32, and a motor 34 that generates a driving force to rotate the rotation shaft 38. The rotation shaft 38 is rotatably supported by the housing 30 and extends parallel to the Y direction. The housing 30 has guide members 35 and 36 that guide the extension direction of the bistable boom 10.

[0038] When the sprocket 32 ​​is rotated by the motor 34, the protrusions 37 engage with the through holes 11 of the bistable boom 10 while the sprocket 32 ​​is rotating, so that the bistable boom 10 can be extended or retracted along the extension direction X. When the sprocket 32 ​​rotates counterclockwise in FIG. 7 , the bistable boom 10 moves in the extension direction X and is pulled out from the retracted portion 12 housed in the housing 33 and extended. On the other hand, when the sprocket 32 ​​rotates clockwise, the bistable boom 10 moves in the direction opposite to the extension direction X (-X direction) and is retracted onto the retracted portion 12 housed in the housing 33.

[0039] The sprocket 32 ​​is provided at a position between the housing portion 33 and the fixed portion 31 in the extension direction X of the housing.

[0040] (extension rod) As shown in FIG. 1, when the extension rod 1 is in the retracted state, the bistable boom 10 is in the retracted state. The bistable boom 10 is stored in the storage section 33 of the housing 30 with its tip pulled out a predetermined distance in the extension direction X. When pulled out a predetermined distance, the extended portion of the bistable boom 10 does not include the extended portion 14, and is composed mostly of the retracted portion 12 and the transition portion 13. Therefore, as shown in FIG. 1 , in the stored state, the radius of curvature of the tip of the bistable boom 10 in the extension direction X is larger than that of the extended portion 14.

[0041] On the other hand, as shown in FIG. 2, when the extension rod 1 is in the extended state, the tip of the bistable boom 10 in the extension direction X consists of an extended portion 14, which has a shape with a relatively small radius of curvature (a shape in which part of a hollow cylindrical shape is cut out along the generatrix).

[0042] (Telescopic boom inside a bistable boom) 1 and 2, in the extension rod 1 in the extended state, the bistable boom 10 and the telescopic boom 20 are arranged so that the telescopic boom 20 is located inside the extended configuration portion 14 of the bistable boom 10. In other words, the outer diameter of the cylindrical member that constitutes the telescopic boom 20 is smaller than the inner diameter of the extended configuration portion 14 of the bistable boom 10, and the position of the central axis of the telescopic boom 20 in the extended state and the position of the central axis of the bistable boom 10 in the extended configuration are at approximately the same position or close to each other.

[0043] (Connection between the bistable boom and the telescopic boom) Of the multiple cylindrical members 21-24 that make up the telescopic boom 20, the cylindrical member 24 that is located at the tip of the extension direction X in the extended form (see FIG. 5(A)) is connected to the tip of the extension direction X of the bistable boom 10. The connection portion between the bistable boom 10 and the telescopic boom 20 will be described with reference to FIGS. 8-10.

[0044] 8 is a perspective view showing the vicinity of the tip in the extension direction X of the extension rod 1 in the stored state. When the extension rod 1 is in the stored state, the bistable boom 10 comprises a transition portion 13 at the tip in the extension direction X. Therefore, the bistable boom 10 has a shape with a relatively large radius of curvature at the connection portion with the cylindrical member 24 at the tip of the telescopic boom 20 in the extension direction X.

[0045] 9 is a perspective view showing the vicinity of the tip of the extension rod 1 in the extension direction X in the extended state. When the extension rod 1 is in the extended state, the bistable boom 10 comprises an extended portion 14 at the tip in the extension direction X. Therefore, the bistable boom 10 has a shape with a relatively small radius of curvature at the connection portion between the cylindrical member 24 and the tip of the telescopic boom 20 in the extension direction X.

[0046] Fig. 10(A) is a cross-sectional view of a cross section orthogonal to the extension direction X of the tip of the extension rod 1 in the stored state, which is a cross-sectional view taken along section D in Fig. 8. Fig. 10(B) is a cross-sectional view of a cross section orthogonal to the extension direction X of the tip of the extension rod 1 in the extended state, which is a cross-sectional view taken along section E in Fig. 9.

[0047] The bistable boom 10 is connected to the cylindrical member 24 at the tip of the extension direction X of the telescopic boom 20 at a connecting portion 15 in the center in the circumferential direction W of the inner circumferential surface of the extension form portion 14 at the tip in the extension direction X.

[0048] The telescopic boom 20 is configured so that in the stored configuration (see FIG. 5(B)), the other cylindrical members 22 to 24 stored in the cylindrical member 21 with the largest diameter are successively pulled out from the cylindrical member 24 with the smallest diameter connected to the tip of the bistable boom 10 by the bistable boom 10, which extends due to the rotation of the sprocket 32. As a result, the bistable boom 10 and the telescopic boom 20 move in unison. The muscle moves and stretches in the same direction (extension direction X).

[0049] (Advantages of the extension rod of the embodiment) According to the extension rod 1 configured as described above, in the extended state, the telescopic boom 20 is arranged inside the extension form portion 14 of the bistable boom 10, and the bistable boom 10 and the telescopic boom 20 are connected and extend in the same direction in conjunction with each other. Therefore, even if an external force that bends or flexes the bistable boom 10 acts on the bistable boom 10 from the open portion of the open cross-sectional shape of the bistable boom 10, the bistable boom 10 is supported by the highly strong telescopic boom 20 arranged inside the extension form portion 14 of the bistable boom 10, and therefore, bending of the bistable boom 10 during the extension operation or after reaching the extended state can be prevented.

[0050] Furthermore, since the telescopic boom 20 in the extended configuration is disposed inside the extended configuration portion 14 of the bistable boom 10 in the extended configuration, most of the outer circumferential surface of the telescopic boom 20 is covered by the cylindrical surface of the bistable boom 10. This makes it possible to reduce the portion of the connecting portion 26 between the cylindrical members of the telescopic boom 20 in the extended configuration that is exposed to the outside. This makes it possible to prevent fine foreign matter such as sand from entering the joint between the cylindrical members at the connecting portion 26.

[0051] Furthermore, during the extension process, the cross-sectional shape of the tip of the bistable boom 10 changes from a nearly linear shape to a shape approaching an arc as the radius of curvature gradually decreases. However, the position of the center in the circumferential direction W hardly moves during the extension process. In other words, the relative positional relationship between the center in the circumferential direction W at the tip of the bistable boom 10 and the cylindrical member 24 at the tip of the telescopic boom 20 in a cross section perpendicular to the extension direction X is almost constant. As described above, in the extension rod 1 of the embodiment, the connection portion 15 between the bistable boom 10 and the telescopic boom 20 is located in the center in the circumferential direction W of the inner circumferential surface of the extension form portion 14 at the tip of the bistable boom 10 in the extension direction X. Therefore, during the extension process of the extension rod 1, it is possible to suppress loads on the bistable boom 10 and the telescopic boom 20 that are connected to each other.

[0052] Furthermore, in the housing 30, a sprocket 32 ​​is disposed between a storage section 33 that stores the retracted portion 12 of the bistable boom 10 and a fixing section 31 to which the telescopic boom 20 is fixed. The shape of the bistable boom 10 in the vicinity of the retracted portion 12 is substantially flat, and the protrusions 37 of the sprocket 32 ​​and the through-holes 11 of the bistable boom 10 engage in this flat portion, so that the driving force can be transmitted from the sprocket 32 ​​to the bistable boom 10 more reliably.

[0053] Furthermore, the radius of curvature of the bistable boom 10 in the width direction Y decreases the further away from the retracted portion 12 in the extension direction X. Therefore, by fixing the telescopic boom 20 at a position away from the retracted portion 12 in the extension direction X, it becomes possible to cover as much of the outer circumferential surface of the telescopic boom 20 as possible with the bistable boom 10, even at the cylindrical member 21 with the largest diameter near the base in the extension form.

[0054] Furthermore, when the bistable boom 10 is pulled out by a predetermined length from the retracted state, it self-extends to the extended state due to the elastic force of the elastic member constituting the bistable boom 10. In the extension rod 1 in the stored state, the bistable boom 10 is stored in a state in which it is pulled out by a predetermined length from the retracted state. Therefore, the self-extension force of the bistable boom 10 can assist in driving the motor 34 for extending the telescopic boom 20. Therefore, the rating of the motor 34 can be made smaller than in an extension rod configured by combining a telescopic boom with a member that does not have such self-extension force.

[0055] As described above, with the extension rod 1 of the embodiment, the low strength of the bistable boom 10 resulting from its open cross-sectional shape can be compensated for by the strength of the highly rigid telescopic boom 20, making it possible to ensure the strength of the extension rod 1 even in environments where gravity is present. Furthermore, the low resistance of the telescopic boom 20 to foreign objects such as sand and dust resulting from the presence of the connecting portion 26 can be resolved by covering the outer circumferential surface of the telescopic boom 20 with the bistable boom 10. Therefore, with the extension rod 1 of the embodiment, sufficient strength can be ensured and reliable extension operations can be performed not only in outer space but also on the surface of the moon or on Earth, where gravity is present and sand and dust is present. [Explanation of symbols]

[0056] 1: Extension rod 10: Bistable boom 11:Through hole 12: Winding form part 13: Transition section 14: Extension form part 15:Connection part 20: Telescopic boom 21, 22, 23, 24: Cylindrical members 26:Connection part 30: Cabinet 31: Fixed part 32: Sprocket 33: Storage unit 34: Motor 35, 36: Guide member 37: Protrusion 38: Rotation axis X: Extension direction Y: Width direction W: Circumferential direction

Claims

1. a bistable boom that can stably hold two configurations, an extended configuration and a retracted configuration, in which in the extended configuration, the boom extends linearly in the extension direction and is maintained with an open cross-sectional shape in which a cross section perpendicular to the extension direction is curved in an arc shape, and in the retracted configuration, the boom is retracted cylindrically around a central axis that is parallel to the width direction perpendicular to the extension direction and is maintained with a cross section perpendicular to the extension direction extended linearly; a telescopic boom comprising a plurality of hollow cylindrical members of different diameters, wherein in a stored configuration, the cylindrical member with the largest diameter has the other cylindrical members stored concentrically inside it, and in an extended configuration, the ends of the cylindrical members are connected to each other to form a multi-stage cylindrical shape; An extension rod having The telescopic boom is disposed within the bistable boom in an extended configuration; an extension rod, wherein one of the plurality of cylindrical members constituting the telescopic boom that is located at a tip in the extension direction in an extended form is connected to a tip end of the bistable boom in the extension direction, and the bistable boom and the telescopic boom extend in the same direction in conjunction with each other.

2. The extension rod according to claim 1 , wherein the bistable boom is connected to the cylindrical member of the telescopic boom at a circumferential center portion of an inner circumferential surface of a tip end portion in an extension direction.

3. 3. The extension rod according to claim 1 or 2, wherein the telescopic boom transitions to the extended configuration together with the bistable boom by the other cylindrical members stored in the cylindrical member with the largest diameter in the stored configuration being sequentially pulled out from the cylindrical member with the smallest diameter connected to the tip end of the bistable boom by the bistable boom extending.

4. the bistable boom has a plurality of through holes spaced apart along the extension direction; a sprocket having a projection that engages with the through hole; a motor that rotates the sprocket to extend the bistable boom; 3. The extension rod of claim 1 or 2, comprising:

5. a housing having a housing portion that houses the bistable boom and a fixing portion to which a cylindrical member with a maximum diameter of the telescopic boom is fixed, the bistable boom is accommodated in the accommodation section in a state in which a tip end of the bistable boom is pulled out in an extension direction from a wound state by a predetermined length, The fixing portion is provided at a position spaced apart from the accommodation portion in the extension direction, The extension rod according to claim 4 , wherein the sprocket is provided at a position between the housing portion and the fixed portion in the extension direction.

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