Abstract:
A collapsible self-supporting structure used in combination with an improved articulating hub assembly. The articulating hub assembly is used as a connector among tubular rod elements which together provide a generally tubular frame matrix used to erect a collapsible self-supporting prefabricated deployable structure where a clear span interior without supporting columns is required.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application is related to my copending application Ser. No. 11/2228,651, filed Sep. 15, 2005. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to collapsible, self supporting structures and an improved articulating hub assembly used as a connector among tubular rod elements. The hub assembly and tubular rod elements provide a generally tubular frame matrix used to erect a collapsible self-supporting prefabricated deployable structures where a clear span interior without supporting columns is required.  
       BACKGROUND OF THE INVENTION  
       [0003]     Portable deployable building assemblies must have a foldable capability so that they may be erected where desired and, when necessary, folded up to a compact form for storage and/or transportation. These portable building assemblies utilize struts, which are tubular rods, as the basic construction unit, that form the skeleton structure and thus the configuration of the portable building assembly. The tubular rods noted above are interconnected with one another by some type of movable interconnecting fastening means such as a hub, so that the completed structure is articulated and collapsible. A plastic, canvas or some other type of durable fabric covering is usually applied to the outside and inner surface planes of the tubular rods to envelope the assembly and provide a covered shelter.  
         [0004]     An example of such a collapsible structure is shown in U.S. Pat. No. 3,185,164, (&#39;164) which discloses a portable structure having a plurality of rods joined by coupling means into groups of three which are inter-related to form a generally hexagonal structural system. The structure disclosed in &#39;164 employs flexible stays or cables to form the extended shape of the structure and render the structure self-supporting. Another example of such a collapsible structure is shown in U.S. Pat. No. 3,710,806, which employs hub-connected multiply-hinged scissor-type linkages where the linkages articulate allowing the structure to expand or contract. Portable structures that utilize elements which maintain the rigidity of the structure are disclosed in U.S. Pat. No. 3,063,521. Like &#39;164, the structures described in U.S. Pat. No. 3,063,521 employ tension elements such as wires or cables to render the structure self-supporting.  
         [0005]     U.S. Pat. No. 3,968,808 (&#39;808) discloses a collapsible self-supporting dome-like structure with a network of pivotal rods interconnected with linking joints. The linking joint holds six rods, each connected to a six-sided metal ring. Each rod is connected onto the ring and is capable of pivoting about the ring. The rod is a permanent attachment and thus cannot be disconnected nor replaced. There does not appear any way to attach a cover to the dome-like structure such as is found in the “keeper” component in the articulating hub assembly of the present invention. Further, the hexagonal ring design described by &#39;808 has six facets, thus offers positions for up to six rods, and the rods must extend radially outward from the linking joint such that rods on opposite sides of the linking joint share a common geometric plane.  
         [0006]     U.S. Pat. No. 4,026,313 also discloses a collapsible self-supporting dome-like structure with a network of pivotal rods interconnected with linking joints. The pivotal device linking the rods together forming the structure is a circular joint. Each joint has only four rods which extend radially outward from the joint such that rods on opposite sides of the joint share a common geometric plane. Each rod contains a plug ending with a small cylinder. This small cylinder is nested inside the joint and allows the rod to rotate. It appears that none of the components is easily interchanged. The top and bottom sections of the hubs in the reference appear to be permanently joined by an adhesive so that none of the rods or plugs can be replaced.  
         [0007]     U.S. Pat. No. 4,512,097 discloses a display panel mounting clip. The clip body is used to connect display panels together. The clip assembly disclosed requires a spring mechanism to create tension and hold the panels together. The present invention requires no springs. The clip disclosed in the reference must be snapped into an opening joining the rods in a circular joint. In the present invention, the circular hub is screwed into the hub section so it is threadedly secured.  
         [0008]     U.S. Pat. No. 4,280,521 discloses a hub assembly for collapsible structures. The hub assembly disclosed in the reference requires a circular retaining ring to hold the “column like elements” or tubes in place. Each tube must be threaded onto a circular retaining ring prior to insertion into the hub section. The tubes are arranged such that tubes on opposite sides of the hub rotate within the same plane. In the hub disclosed in U.S. Pat. No. 4,280,521, the hub sections are secured in place by use of an adhesive to fuse the two hub sections together permanently. The tube members within the structure, therefore, are not easily replaceable since the hub sections cannot be replaced without destroying them.  
         [0009]     In the present invention no circular ring is present or required to hold the rods together inside the hub to allow rotation. The present invention as explained in detail hereinafter, requires that each tube have its own tang, each with its own roll pin to independently nest inside the hub body, thus no ring is present. It is an object of the present invention to provide a hub assembly that has the capability of quickly and easily removing the strut which is contained within the hub.  
         [0010]     The U.S. Pat. No. 4,280,521 design, described above, uses a three piece clamping device to hold or attach a skin or cover to the structure. One piece is a plug that is incorporated inside the hub section and is fused into the hub sections. The second piece is a flat disc. The third piece is an element which is a screw. The screw is threaded into the plug and holds the clamp down. A screw driver would obviously be required to remove the clamp if or when the cover, the skin or the tubes have to be replaced.  
         [0011]     Soviet Patent No. 1,392,220 discloses a joint between rods which possesses two pressure plates whose surfaces face each other and have spherical loons with slits from each loon to the outer outline of the pressure component plate. Screws appear to join the upper plate with the lower plate to hold the ball joints in place. The reference does not disclose a hub assembly such as described and claimed herein.  
         [0012]     Collapsible frame structures for supporting tents or other outdoor shelters are disclosed in U.S. Pat. Nos. 563,376; 927,738; 1,773,847 and 2,781,766. These structures do not possess the improved hub of the present invention to allow the flexibility found in the structures using the hub of the present invention. Other collapsible structures disclosing some form of connecting means to hold the tubular rods in place are described in U.S. Pat. Nos. 3,968,808; 4,026,313; 4,290,244; 4,437,275; 4,473,986; 4,512,097; 4,522,008; 4,561,618; 4,579,066; 4,607,656 4,641,676, 4,689,932, 4,761,929, 4,779,635 and 4,838,003.  
         [0013]     The typical prior art structures disclosed in the references cited above suffer from a common problems. With respect to the collapsible structure, due to the immense size which is needed in many present military and civilian applications, it is often difficult to erect (i.e., to raise or to lower) the skeleton structure. The inherent difficulties are that to erect or to collapse the structure requires several workers, takes a significant amount of time, and requires special tools and equipment. In addition, in the collapsed state, existing structures are too large. Thus the structures are bulky and heavy and have a complicated construction. The deployable portable building assemblies must be capable of being collapsed quickly an easily folded up into a compact structure.  
         [0014]     The type of building assemblies using the hub disclosed in U.S. Pat. No. 5,797,695 (&#39;695) to A. Jon Prusmack conveniently collapse to a bundle having a cylindrical configuration along its longitudinal axis when stored.  
         [0015]     Cross sectional representation of the outline of the perimeter of an example of the structure disclosed in the &#39;695 patent is depicted in  FIG. 1A  with five “sections” or “quads” using a specific and small diameter tubular rod.  FIG. 1B  represents the perimeter of the shelter of present invention and depicts seven “quads”, I through VII using a much larger diameter tubular rod have side and diagonal elements formed from tubular strut elements connected at each end and in the center to a hub. Practical and structural considerations limit each of the five sections found in the &#39;695 prior art structure to 5 feet square. Thus the structure in the embodiment depicted in  FIG. 1A  has a maximum horizontal distance between quad  1  and quad  5  of 11.75 feet. The limitations stem from the design of the hub where the rods on opposite sides of the hub share the same geometric plane, thereby limiting the diameter of the rods to 0.5 inches if acceptably compact collapsed structures are to result. The limitations on the size of the structure result from structural properties of practical 0.5 inch diameter rod and structural requirements of erected structures.  
         [0016]     In order to function efficiently, the dimensions of each of the rectangular sections comprising the structure must be suitable to allow the structure to be erected speedily as well as allowing the structure to be collapsed speedily.  
         [0017]     As noted above, each of the quads of the commercially efficient deployable structure, as contemplated in the &#39;695 patent as depicted in  FIG. 1A , possesses tubular strut elements that together with the hubs measure about 5 feet in length and width. The diameter of the prior art tubular strut elements contemplated by the &#39;695 patent is about ⅝″ (0.625″). These length/diameter dimensions allow the tubular rods of the structure to be collapsed into the cylindrical configuration noted above. Using the 5 feet quad dimensions and the tubular strut of ⅝″ diameter, when the structure is erected, the distance from the ground to the center point of quad  3  of FIG. 8.25 feet.  
         [0018]     When attempting to construct a portable building assembly having greater height, width and length dimensions compared with the &#39;695 assembly, it was determined that serious problems were encountered with the structural integrity of the shelter.  
         [0019]     In the situation in which one is forming a larger deployable structure than that enabled by the &#39;695 patent, a larger, stronger tubular strut would be required than the existing struts having a diameter of ⅝″. The larger diameter strut using the same size hub as disclosed in the &#39;695 Patent will not produce a shelter possessing the required features necessary for prompt tactical deployments. An increased diameter strut (i.e., greater than ⅝″), used in combination with the prior art hub, will not collapse to an adequately compact bundle when collapsing the structure. Accordingly, the structure cannot be folded to possess the required volume in the collapsed state or “low racking volume.” 
         [0020]     If one desires to construct a larger shelter unit as depicted in  FIG. 1B , having a height, for example, of 18 feet up to 32 feet, and accordingly a wider horizontal space between the sides I and VII , the additional stress on the tubular struts in the expanded structure of the assembly as well as other factors must be considered. The increased building dimensions does result in increased weight. If one opts to increase the diameter of the tubular struts comprising the quads in the construction of a larger deployable shelter to compensate for the increase in stress resulting from the wider span and added weight, substantial construction problems result. If the tubular strut is increased to, for example, 7 feet, the complementary angles between sections I and II, II and III and III and IV, etc. will be changed, so the symmetry which is inherent in the &#39;695 prior art shelter is lost and the structure is totally different and unsuitable for the required prompt set-up and fold-up.  
         [0021]     In my copending application, Ser. No. 11/228,651 certain basic features of articulating hub assemblies are also disclosed. As noted, that application is incorporated by reference herein.  
       BRIEF SUMMARY OF THE INVENTION  
       [0022]     The present invention relates to a portable, deployable building assembly comprised of struts interconnected by hubs. Another feature of the present invention is an improved hub which links the tubular rods together in forming the building structure.  
         [0023]     The unique articulating hub assembly of the present invention is an integration of eight separate components (quads) that when connected form a novel means for pivotally joining a network of tubular interconnecting rods forming the matrix for a collapsible structure. Multiple assemblies are used as pivotal devices for the movement of tubes to allow the quick erection and striking of a tubular frame supported structure.  
         [0024]     A first significant feature of the present invention is to allow the tubes to articulate or move freely when either upward, (i.e., vertical) or opposing side,( i.e., horizontal) forces are applied. These forces cause a 180° (i.e., a semi-circular) rotation of the tube components which comprise up to eight tubes per hub.  
         [0025]     More specifically, with respect to the collapsed network of tubular struts, assemblies, etc. laid out prior to erection, when manual upward pressure is applied at 90° (i.e., perpendicular) to the ground at specific location on the network, multiple hub assemblies are displaced from positions physically contacting the ground to specific elevated positions above the ground. The upward vertical force creates an action that moves the articulating hub assemblies of the present invention from static positions to tension positions and forms a structure of interconnected tubes and articulating hub assemblies that is self-supporting. The resultant structure has four physical sides. The size and the shape of the structure can vary based upon the length of the tubes and the location of scissor points.  
         [0026]     To collapse the frame to its original position on the ground, simultaneous and opposing forces are applied on each of the four sides of the structure, 180° to each other and 90° to the vertical (along the 0° or X-axis), to specific articulating hub assemblies.  
         [0027]     This action allows the tubular strut to move from a tension position with the assemblies above ground, back to a static position and collapse down to the original location on the ground.  
         [0028]     The appropriate diameter of the hub of the present invention is a function of the size of the deployable structure to be assembled. The hubs are of different size depending upon the dimension of the shelter in which they are used. The hub of the present invention has an octagonal shape which allows larger diameter tubular struts of ¾ (0.75) inch or greater which are fixed in the slits in the hub to rotate when erecting or collapsing the structure.  
         [0029]     Further, the slits which secure the tubular struts into the hub are offset at a 45° angle so that the struts emanating radially from any given hub rotate within a unique geometric plane not shared with any other rod, thus the rods can easily fold in on themselves and provide a compact bundle for storage or expand easily for a quick set-up.  
         [0030]     There are two embodiments of the hub of the present invention. For the purposes of this disclosure, they are designated the “J” and the “M” hubs. The hubs have substantially identical configuration with the “J” hub having a larger overall dimension. Where not specifically mentioned herein, the drawings serve to cover both embodiments. To facilitate assembly of the hub, the bottom half of the assembly is substantially thicker than the top, and contains slits to capture the tang and pin elements of the rods.  
         [0031]     A cross sectional view of the configuration of the struts and hubs shelter of the present invention is depicted in  FIG. 1B . The quads formed using the “J” hub are maximally 7 feet square with a height when the structure is erected between the ground to the center point of quad IV of up to 12.5 feet. The quads formed using the “M” hub are maximally 4′10″ feet square, with a height when the structure is erected between the ground to the center point of quad IV of up to 8.75 feet. The addition of two quads to that disclosed in the prior art &#39;695 patent shelter allows larger shelters to be constructed. The horizontal distance between quad I and quad VII in  FIG. 1B  will vary depending upon which hub is used.  
         [0032]     A second significant feature of the articulating hub assembly of the present invention is the ability to secure fabric covers (covering the tubular frame network) to the hub body and allow the two covers (interior and exterior) to move simultaneously with the tubular frame. In the assembly there is a mushroom shaped keeper element, having a top and a shaft extended downwardly therefrom, wherein the shaft is capable of being inserted through the hub top, and the shaft is capable of being secured to the hub bottom. The central opening of the hub bottom may be threaded, and the shaft of the shaft of the keeper element also threaded to coincide with the central threaded opening of the hub bottom to allow the keeper to threadedly engage the hub body. Where a cover is placed over the tubular structure, the keeper element may secure the cover by holding the cover between the top of the keeper element and the hub top in a configuration where the shaft of the keeper element is placed through an opening in the cover and secured to the hub body. The top of the keeper is contoured to match the slope of the exposed surface of the hub cover.  
         [0033]     Objects and features as well as additional details of the present invention will become apparent from the following detailed description and annexed drawings of the presently preferred embodiments thereof, when considered in conjunction with the associated drawings.  
         [0034]     The collapsible structure of the present invention is a substantial improvement over prior art reference assemblies. The present invention enables the rapid deployment of larger structures from a given collapsed volume, relative to the prior art, and enables collapsible structures with absolute dimensions larger than previously possible. In particular the hub assembly of the present invention is a substantial improvement over prior art in that it enables rods of the deployable structure to form a more compact collapsed form and enables the use of larger diameter rods where required for larger or more robust structures.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]      FIG. 1A  is a front view cross-sectional representation of the perimeter outline of a deployable structure as found in the prior art.  FIG. 1B  is a front view cross-sectional representation of the perimeter outline of the deployable structure of the present invention using the “J” hub.  FIG. 1C  is a front view cross-sectional representation of the perimeter outline of the deployable structure of the present invention using the “M” hub.  
         [0036]      FIG. 2  is an oblique view of hubs and tubular struts as they appear when the deployable shelter is in a folded state.  
         [0037]      FIG. 3  is a magnified view of a portion of the structure depicted in  FIG. 2 .  
         [0038]      FIG. 4  is an exploded oblique view of the improved hub of the present invention.  
         [0039]      FIG. 5A  is a plan view of the top of the improved hub of the present invention with the tubular struts and keeper in place.  
         [0040]      FIG. 5B  is a plan view of the bottom of the improved hub of the present invention with the tubular struts and keeper in place.  
         [0041]      FIG. 6A  is a plan view of the bottom of the improved hub with partial cutaway exposing the interior surface of the top of the improved hub of the present invention.  
         [0042]      FIG. 6B  is a plan view of the top of the improved hub with partial cutaway exposing the interior surface of the bottom of the improved hub of the present invention.  
         [0043]      FIG. 7A  is a plan view of the interior surface of the bottom half of the improved “J” hub of the present invention.  
         [0044]      FIG. 7B  is a plan view of the interior surface of the top half of the improved hub of the present invention.  
         [0045]      FIG. 8A  is a plan view of the interior surface of the bottom half of the improved “M” hub of the present invention.  
         [0046]      FIG. 8B  is a plan view of the interior surface of the top half of the improved hub of the present invention.  
         [0047]      FIG. 9  (A and B) is an oblique view of the top section of the “M” hub and the “J” hub showing the relative difference in size (not drawn to scale).  
         [0048]      FIG. 10A  is a side view of the improved “J” hub of the present invention.  
         [0049]      FIG. 10B  is a cutaway cross sectional view of the improved “J” hub of the present invention.  
         [0050]      FIG. 11A  is a side view of the improved “M” hub of the present invention.  
         [0051]      FIG. 11B  is a cutaway cross sectional view of the improved “M” hub of the present invention.  
         [0052]      FIG. 12  is an oblique view of two sections (“quads”) of a deployable structure showing the positions of the hub in place.  
         [0053]      FIG. 13  is an oblique view of two hubs connected to tubular struts in place.  
         [0054]      FIG. 14  depicts the deployable shelter erected and in place with the keepers secured to ground lines.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0055]     As noted above, the present invention relates to a deployable shelter and an articulating hub assembly which serves to connect tubular rods that comprise the basic construction elements for a prefabricated, self-supporting, deployable structure.  
         [0056]     Tubular struts  150  and two hubs  8  and  9  of the present invention, with the tubular struts in their intermeshed orientations when the structure is in a folded state, are shown in  FIG. 2 . When viewing the hubs as depicted in  FIG. 2 , the “bottom” element,  10 , of hub assembly  8 , is shown connected to four tubular struts, and the “top” element,  11 , of hub assembly  9  is shown also connected to four tubular struts. The tubular struts are connected to the hub by means of a plug  151  affixed within the interior of tubular strut  150 . Plug  151  is connected to tang  154  which is held within the hub body  8 .  FIG. 2  shows only  7  struts for clarity.  
         [0057]      FIG. 3  shows the “bottom”  10  of hub assembly  8  of the present invention, with four tubular struts  150  in their folded and intermeshed positions. Similar to  FIG. 2 , the tubular struts  150  are fastened to plug  151  which is in turn fastened to tang  154  which is captured within hub body  8  as is described in further detail below.  
         [0058]      FIG. 4  is an orthogonal exploded view of the articulating hub assembly of the present invention depicting the bottom  10  and top  20  sections of the hub body with the connecting end of tubular struts  150  and  270  of the skeletal matrix as well as other relevant parts shown in their respective locations when the assembly is in use. As illustrated in  FIG. 4 , within the end of tubular strut  150  is fastened plug  151  with the assistance of ribs  152 . Plug  151  is generally and preferably cylindrical in shape and has a crown  157  at one end which rests against shoulder  158  when assembled. The diameter of the portion of plug  151  beyond crown  158  is substantially the same as the inside diameter of the tubular strut elements which form the skeletal matrix of the shelter. When assembled, a rivet (not shown) secures tang tail  153  in plug  151  to the tubular element (not shown). Head  159  of tang  154  is wider than tail  153  and merges therewith at shoulder  168 . Tang  154  is captured within the hub assembly by means of roll pin  330  which is inserted through opening  156  in tang  154 . Roll pin  330  is captured within groove  200  (shown in  FIG. 6B ) in hub bottom  10  so that tang  154  is captured by hub  8  but able to move within slits  160  and  170  in hub bottom  10  and top  20 , respectively. Slits  160  and  170  are in registered alignment.  
         [0059]     Into radial slits  160  and  170  there is inserted a tang  154  having a head  159  and a tail  153 . Tang  154  is inserted through a plug  151  which is also inserted within the end of tubular strut  150 . Tang  154  is held in place within hub bottom  10  by roll pin  330  which is inserted through an opening  156  through head  159 . Roll pin  330  is secured in a groove (not shown in  FIG. 4  but shown in  FIG. 6B ) in the underside of hub bottom  10 . (See  FIG. 6B .)  
         [0060]     The tail  153  of tang  154  is sufficiently long to extend radially outward from radial slits  160  and  170 . Tail  153  of tang  154  possesses a width substantially the same as is present in a slit that extends radially through plug  151 .  
         [0061]     Hub bottom  10  has seven slits analogous to slit  160  ( 161  through  167 ), and hub top  20  has seven slits analogous to slit  170  ( 171  through  177 ), in registered alignment with the slits in the hub bottom.  
         [0062]     Within hub bottom  10  are openings  180  through  187 . These openings are recessed and are in registered alignment with openings  210  to  217  in hub top  20 . Each opening  180  through  187  and  210  to  217  receives a means for securing bottom  10  and hub top  20 . Preferably the securing means is a fastener  280  through  287 , not shown in this view. Openings  180  through  187  in the hub bottom  10 , and  210  to  217  on the top  20  are preferably recessed so the heads of the fasteners and the nuts (not shown) lie flush with the respective surfaces of the hub. The nuts and fasteners referred to are tightened to secure hub top  20  to hub bottom  10 .  
         [0063]     The openings in hub top  20  also are provided with recesses  220  to  227 . Recesses  220  to  227  are configured to both capture nuts  230  to  237  and enable them lie flush with the respective surfaces of hub top  20 . The fasteners and nuts  230  to  237  are threaded so that they may be threadedly engaged.  
         [0064]     To improved structural performance and minimize weight, hub top  20  contains wells  240  to  247 .  
         [0065]     Hub bottom  10  has a central opening  250  with threads  251  whereas hub top  20  has a larger central opening  252 .  
         [0066]     Hub assembly  8  may be equipped with one or more keepers,  260 . The keeper is mushroom shaped, with a top  261  and a shaft  262 . The top  261  and has one central well  263  about which are distributed four wells  264  to  267 . The shaft  262  of the keeper is threaded to match that of central opening  250  so that it may engage threads  251  of hub bottom  10 . In addition to the nuts and fasteners noted above, keeper component  260  also secures hub bottom component  10  to hub top component  20 .  
         [0067]     Hub assembly  8  may connect anywhere from one to eight tubular struts. Shown in  FIG. 4  are two tubular struts,  150  and  270 . Analogous to tubular strut  150 , plug  271  is fastened within tubular strut  270 . Tang  272  is inserted in to plug  271 . Tang  272  and plug  271  are fastened to strut  270  by means of a rivet, not shown. Tang  272  is also captured within hub assembly  8  by means of a roll pin which lies within a groove that is perpendicular to slit  164 .  
         [0068]     This view does not show the fabric which covers the tubular structure of the shelter. The cover can be any suitable fabric such as canvas, nylon, polyester, etc. and can be impregnated with fire retardants, insect repellent compositions, etc.  
         [0069]      FIG. 5A  is a plan view of the top surface of the assembly depicted in  FIG. 4  showing some of the elements detailed in  FIG. 4 , including the octagonal shape of hub top  20  of hub assembly  8 .  FIG. 5A  includes hub assembly  8  with eight tubular struts each with a plug, as illustrated by element  151 , and tang  154 , each tang inserted within a slit as illustrated by element  160 . Thus each strut is connected to hub  8  by means of tangs  154 ,  272  and  300  to  305  which in turn engage plugs  151 ,  271  and  307  to  312 . The view shows eight fasteners as illustrated by elements  280  to  287  which are used to secure, in combination with eight fasteners (not shown) the superior element to the inferior element comprising the hub. Keeper  260  is fixed to the hub using any suitable means, and a loop  290 , to hold wind lines, is secured to central well  263  of keeper  260  by any suitable means. The loop is generally permanently attached to keeper component  260 .  
         [0070]      FIG. 5B  is a plan view of the bottom surface of the assembly depicted in  FIG. 4  showing some of the elements detailed in  FIG. 4  including the octagonal shaped hub bottom  10  of hub assembly  8  as it is used in combination with tubular struts the comprise the matrix of the deployable structure in the erected state.  FIG. 5B  includes hub assembly  8  with eight tubular struts  150 ,  270 ,  313  to  318  each within a slit as illustrated by elements  160  to  167 . Struts  150 ,  270  and  313  to  318 , are engaged to the hub by means of tangs  154  and  300  to  305  which are in turn engaged with plugs  152 ,  271  and  307  to  312 . Hub bottom  10  has a central, threaded opening  250 , within which is threadedly engaged the shaft  262  of the keeper  260 . Hub bottom  10  has nuts,  230  to  237 , which threadedly engage fasteners  280  to  287  (the tip of which are shown protruding through the center of nuts  230  to  237 ) to secure hub bottom  10  to hub top  20 . The protruding tip  313  of hub keeper  260  appears in the opening in the center of the hub.  
         [0071]     Referring to  FIG. 4  and where necessary,  FIG. 5A  and  FIG. 5B , hub  8  comprising the present invention therefore is an octagonal unit made up of two separable sections, hub bottom  10  and a hub top  20  (See also  FIG. 5A  and  FIG. 5B ).  FIG. 4  specifically depicts the superior side of hub bottom  10  and the inferior side of hub top  20 .  
         [0072]     Accordingly, hub  8  contains  8  peripheral edges  101  to  108  which are continuously connected, each to the next, around its periphery thus forming  8  vertices each subtending an angle of 45°. Thus for each vertices, as for example between edge  101  and  102 , the angle is 45°.  
         [0073]     Immediately past the intersection of each of edges  101  through  108  around the periphery of the unit, slits  160  through  167  and  170  to  177  are cut normal to the peripheral edge in question into hub  8  in direct alignment through hub bottom  10  and hub top  20  that comprise hub  8 . Each of the aforementioned  8  vertices formed by the intersecting edges  101  through  108  around the periphery subtends an angle of 45°. Accordingly, proceeding in a clockwise manner around the octagonal periphery of the hub with its defined sections, the adjacent slits cut into the hub each form an angle of 45° with the succeeding and preceding edges.  
         [0074]      FIG. 6A  depicts a plan view of hub assembly  8  showing, in a partial cut-away view, hub top  20  and hub bottom  10 . Shown are the struts,  150 ,  270  and  313  to  318 , each connected by way of a plug,  151 ,  271 ,  307  to  312 , respectively, to a tang,  154 ,  272 ,  300  to  305 , respectively, which is captured within the hub top  20  by means of a roll pin captured within a groove (not shown). The hub top  20  is secured to hub bottom  10  by means of a fastener, two of which are shown in this representation,  281  and  282 . The cut-away portion of the drawing shows two of the eight wells  326  and  327  in hub bottom  10  as well as two of the eight openings  184  and  185  in hub bottom  10 .  
         [0075]      FIG. 6B  depicts a plan view of hub assembly  8  showing, in a partial cut-away view, hub bottom  10  and hub top  20 . Shown are struts  150 ,  270  and  313  to  318 , each connected by way of a plug,  151 ,  271 ,  307  to  312 , respectively, to a tang,  154 ,  272 ,  300  to  305 , respectively, which is captured within the hub top  20  by means of a roll pin, two of which,  330  and  331 , are shown. The roll pins,  330  and  331  are shown, are captured within hub top  20  by means of a groove, grooves  200  and  201  are shown. The hub top  20  is secured to hub bottom  10  by means of fasteners each of which is threadedly secured by a nut. In this view six nuts,  230  to  235 , are shown. The cut-away portion of the drawing shows two of the eight wells  340  and  341  in hub top  20  as well as two of the eight openings  210  and  211  in hub top  20 .  
         [0076]      FIG. 7A  depicts a plan view of a hub bottom of a second example of the invention. Depicted in  FIG. 7A  is the hub bottom  400  which has eight edges,  410  to  417  and eight slits,  420  to  427 . Perpendicular to each slit is a groove,  430  to  437 , for the purpose of capturing the roll pins (not shown) of the tangs (not shown). The hub bottom has eight interior wells,  440  to  447 , and eight exterior wells,  450  to  457 , to facilitate manufacture and improve the structural properties of the component. Hub bottom  400  has a central opening  401  which is threaded on its interior surface. The central opening is within a boss  402 . Hub bottom is also provided with eight openings,  460  to  467 , for fasteners (not shown).  
         [0077]      FIG. 7B  depicts a plan view of a hub top of a second example of the invention. Depicted in  FIG. 7B  is hub top  500  which has eight edges,  510  to  517 , and eight slits,  520  to  527 . The hub top has eight wells,  530  to  537 , to improve the manufacturability and structural performance of the component, and eight openings,  540  to  547 , for fasteners (not shown). The hub top  500  has a central opening,  501  with an interior dimension sized to accept boss  502 .  
         [0078]     To explicate the spatial relationships of the hub edges and the slits cut therein, reference is made to  FIG. 6A , which describes example 1 of the present invention.  FIG. 7A , which describes Example 2 of the present invention has analogous relationships. Referring to  FIG. 6A , slits  160  and  170  are aligned and positioned normal to edge  106 ; likewise slits  161  and  171  are positioned normal to edge  107 ; likewise slits  161  and  172  are positioned normal to edge  108 , and so it continues around the periphery of the octagonal hub. However each pair of slits (e.g.,  160 / 170 ,  161 / 171  and  162 / 172 ) which are normal to their particular edge ( 106 ,  107  and  108  respectively) form an angle with the preceding and succeeding slits. Thus, the slits in the hub are all positioned at angle of 45° with respect to one another.  
         [0079]     Each segment of hub  8  defines an area formed between each of slits  160  through  167  and  170  to  177  which is an incomplete right triangle.  FIG. 6A  shows that if a line following each adjacent slit were drawn from the edges of the hub and extended until they intersected, eight right triangles would result. In practice, the actual slits  160  through  167  and  170  to  177  cannot be so extended as the integrity of hub  8  would be destroyed.  
         [0080]      FIG. 8  depicts plan views (not drawn to scale) of the interior surface of the bottom half of the improved “M” hub of the present invention and the interior surface of the top half of the improved “M” hub of the present invention.  
         [0081]      FIG. 9  depicts oblique views of the invention, Example 1 in  FIG. 9A  and Example  2  in  FIG. 9B .  FIG. 9A  shows the hub top  20  and hub bottom  10  in their assembled orientation. The boss  273  of hub bottom  10  is shown within the central opening  252  of hub top  20 . The slits of the hub top  170  to  177 , are in registered alignment with those of the hub bottom,  160  to  167 . Shown are openings  210  to  217  for fasteners (not shown).  FIG. 9B  shows hub top  500  and hub bottom  400  in their assembled orientation. Within hub top  500  is central opening  501 . Within central opening  501  is boss  402  of hub bottom  400 . As in Example 1, the slits of the hub top  540  to  547 , and the slits of the hub bottom  420  to  427 , are in registered alignment. Shown within hub top  500  are openings  530  to  537  for fasteners (not shown).  
         [0082]      FIG. 10A  depicts a side view of the hub assembly  8 , comprised of top  20  and bottom  10 , showing only two sets of struts  150  and  270 , plugs  151  and  271  and tangs  154  and  272 , for clarity. Also shown is loop  109  captured within keeper  260  by knot  110 . Keeper  260  is shown in its assembled position threadedly secured to hub bottom  10 .  
         [0083]      FIG. 10B  depicts a side view taken along the line  10 - 10  of  FIG. 5A  the octagonal embodiment showing hub assembly  8 , comprised of hub top  20  and hub bottom  10 . Threadedly secured in hub bottom  10  is keeper  260 . For clarity, only two plugs  151  and  271 , captured within two struts  150  and  270  to which are secured two tangs  154  and  272  are shown. The tangs are secured to the hub assembly by means of roll pins  330  and  334  which reside in grooves. For clarity only groove  200  is shown. Hub bottom  10  is thicker from its underside to the top surface thereof than the thickness of hub top  20 . As depicted also in  FIG. 6A  and  FIG. 6B , at the center of hub bottom  10  there is a boss  273  with a threaded opening  250  extending upwardly from the upper surface of hub bottom  10 . Hub top  20  has an opening  252  in the center extending through its thickness which opening has a diameter sufficient to accommodate boss  273 . Boss  273  of hub bottom  10  is centered in alignment with opening  252  of hub top  20  and is of sufficient depth so that its terminal portion is flush with the upper surface of hub bottom  10  when the upper flat surface  190  of hub bottom  10  is continuously throughout in contact with the lower flat surface  191  of hub top  20 . Keeper component  260  is threadedly secured within threaded opening  250  and serves to secure hub bottom  10  to hub top  20 .  
         [0084]      FIG. 12  depicts an isometric view of segments of a deployable shelter showing a plurality of articulating hub assemblies  600  to  615  connected to tubular struts  620  to  631  together forming the matrix upon which the fabric cover  700  (not shown) rests and to which it is secured. From the perspective of fabric  700  (not shown) which will cover the matrix, the assembly has both external loops  710  to  712  and internal loops  720  to  722 .  
         [0085]      FIG. 13  is an exploded view of a portion of the matrix depicted in  FIG. 12  showing the spatial relationship of the hubs  100  with inferior section  10  and superior section  20 , tubular struts  150 , fabric  600 , keeper component  134  and loop  135 .  
         [0086]      FIG. 14  is a schematic diagram of a portion of a typical deployable shelter showing securing lines  800  and  801  attached to external loops  810  and  811 .  FIG. 14  depicts a substantial portion of the deployment shelter covered with protective fabric  700  and the balance of the shelter uncovered with tubular struts  820  exposed. The benefit of the shelter directly resulting from the articulating hub assembly is the portability of same and ability to raise large structures from small transporting packages. For example, an assembled shelter covering 386 ft 2  can be carried to the site for striking in a parcel 5 ft×3 ft×2 ft.  
         [0087]     All the components comprising the deployable shelter described hereinabove are interchangeable. The hub sections are joined together using screws making replacement a simple step. Also the tubes can be individually replaced without having to remove the entire collection of tubes before the individual tube in the collection is replaced such as is the case in the prior art.  
         [0088]     Thus while there have been shown, described and pointed out fundamental features of the invention as applied to currently preferred embodiments thereof, it will be understood that various omissions and substitutions and changes in form and details of the method and apparatus illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. In addition it is to be understood that the drawings are not necessarily drawn to scale but that they are merely conceptual in nature. It is the intention, therefore, to be limited only by the scope of the claims appended herewith.