Abstract:
Apparatus and methods for extending a retractable mast include engaging at least three flexible bands such that each band forms a side of a mast. Each band includes a right edge side and a left edge side, each edge having disposed thereon a set of spaced teeth, each tooth having a slot disposed therein and a tab disposed between adjacent teeth, the tab configured to engage the slot of an opposing tooth.

Description:
RELATED APPLICATIONS 
       [0001]    The present application is a continuation-in-part of, and claims priority from: U.S. application Ser. No. 12/883,672, filed Sep. 16, 2010, which, in turn, claims priority from U.S. application Ser. No. 11/406,500, filed Apr. 19, 2010 which, in turn, claims priority from U.S. Provisional Application No. 60/674,345 entitled “Autonomous or Controlled Robot for Undervehicle Inspection” filed Apr. 19, 2005; U.S. Provisional Application No. 60/674,346 entitled “Sensor/Camera Back Pack Lift” filed Apr. 19, 2005; and U.S. Provisional Application No. 60/755,054 entitled “Zipper Mast Lift” filed Dec. 30, 2005, assigned to the assignee hereof. All of the above-listed applications are hereby expressly incorporated by reference herein. 
         [0002]    The present application further claims priority from U.S. Provisional Application No. 61/766,297 entitled “ZipperMast dual lock system” filed Feb. 19, 2013, and U.S. Provisional application Ser. No. 13/779,877 entitled “Situational Awareness Mast” filed Feb. 28, 2013. 
     
    
     TECHNICAL FIELD 
       [0003]    The disclosed embodiments relate to lift mechanisms, and more particularly, to apparatus and methods for extending a retractable mast. 
         [0004]    Lift mechanism technology includes, but is not limited to, hydraulic, pneumatic, and link type structures that may be combined together to form a rigid structure. 
       BACKGROUND 
       [0005]    Extendable masts have seen applications in both the commercial and military markets. For example, electronic packages mounted atop retractable masts include communication and sensor devices, i.e., antennas, cameras and microphones, for collecting sensory data and/or transmitting the collected data to a remote location. 
         [0006]    As the deployment of mobile surveillance and communication systems increases, lightweight, portable, mobile, and reliable retractable platform support systems may be desirable. 
       SUMMARY 
       [0007]    A method for extending a retractable mast having at least three flexible bands is disclosed. Each band including a left edge portion, a right edge portion, and a flat body therebetween, each of the right edge portion and the left edge portion of the band has a series of alternating teeth and tabs disposed thereon, each tooth having a slot disposed therein. 
         [0008]    The method includes extending the retractable mast by drawing together, by an engagement rotor, flexible bands, wherein the left edge portion of one of the bands engages the right edge portion of an adjacent band of the at least three flexible bands. 
         [0009]    A first locking mechanism includes interlocking teeth disposed on the left edge portion of one flexible band with teeth disposed on the right edge portion of an adjacent flexible band. Each tooth includes a crown portion having an upper bent portion and a lower bent portion, and interlocking the teeth includes interlocking the upper bent portion within a notch cut at a lower base portion of an upper opposing tooth, and interlocking the lower bent portion within a notch cut at an upper base portion of a lower opposing tooth, the upper and lower bent portions angled in a same direction so as to extend over the adjacent flexible band. 
         [0010]    A second locking mechanism includes a slot, disposed in each tooth, receiving a tab disposed between adjacent teeth on an adjacent band. 
         [0011]    The housing further comprises a feed mechanism to draw the at least three band together from respective spools, causing the locking mechanisms to engage and form a rigid mast. When operated in reverse, the feed mechanism retracts the mast, separates the bands, and allows the bands to rewind on their respective spools. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The disclosed embodiments will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the disclosed embodiments, wherein like designations denote like elements, and in which: 
           [0013]      FIG. 1  is a perspective drawing of a lift mechanism extending a retractable mast from a set of flexible bands, according to an example of the present disclosure; 
           [0014]      FIG. 2  is a view taken along lines  2 - 2  of  FIG. 1 , according to an example of the present disclosure; 
           [0015]      FIG. 3  is perspective view of a portion of the flexible band, according to an example of the present disclosure; 
           [0016]      FIG. 4  is a plan view of a portion of the flexible band, according to an example of the present disclosure; 
           [0017]      FIG. 5  is perspective view of a bottom portion of the retractable mast, according to an example of the present disclosure. 
           [0018]      FIG. 6A  is a perspective drawing of a cable being drawn from a cable pan during the extending of a retractable mast, according to an example of the present disclosure; 
           [0019]      6 B is a perspective drawing of a cable being coiled in a cable pan during retraction of a mast, according to an example of the present disclosure; 
           [0020]      FIG. 7  is a perspective drawing of another example of the present disclosure; 
           [0021]      FIG. 8  is a block diagram of the lift mechanism, according to an example of the present disclosure; 
           [0022]      FIG. 9  is a perspective drawing of one embodiment of a retractable shield for the lift mechanism, according to an example of the present disclosure; 
           [0023]      FIG. 10  is an embodiment of a robotic device incorporating the lift mechanism, according to an example of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]      FIG. 1  illustrates one embodiment of an apparatus  10  for extending a retractable mast  100 . The retractable mast  100  includes a platform  194  on which a device or devices  168  may be mounted. The retractable mast  100  is formed from at least three flat flexible bands  102 ,  104 ,  106 , each band having a set of alternating tabs and slotted teeth disposed along opposite edges of the bands. The teeth of one band engage the teeth of an adjacent band in a first interlocking relationship to hold the bands in a rigid formation. Further still, a tab disposed between adjacent teeth of one band engages a slot in each tooth of the interlocked band to form a second interlocking relationship to further secure the bands and form a stable mast that will resist unraveling under adverse conditions. 
         [0025]    In one embodiment, the apparatus  10  of  FIG. 1  illustrates a camera/sensor and microphone package  168  being elevated by mast  100  rising from a base unit  78  that comprises three pairs of spaced apart upright support members  70 . Each pair of upright support members  70  respectively supports a spool  82 ,  84 ,  86  of coiled bands  102 ,  104 , and  106  rotatably mounted along a horizontal axis. 
         [0026]      FIG. 1  further depicts a feed mechanism that includes engagement rotor  156  that is operable to draw together bands  102 ,  104 , and  106  from spools  82 ,  84 , and  86  into a mast having a substantially triangular cross section (see  FIG. 2 ). The bands may pass beneath rollers  76  that guide the bands towards the engagement rotor  156 . Turning of engagement rotor  156  causes the bands to interlock extends mast  100 , elevating platform  194  that in at least one embodiment supports camera/sensor package  168 . 
         [0027]    In some embodiments, engagement rotor  156  is rotatably mounted to the base  78  along an axis of rotation in a direction of the extension and retraction of the mast, and may be positioned at a center of a triangular formation of the three bands  102 ,  104  and  106  as best depicted in  FIG. 2 .  FIG. 2  further shows a section view of mast  100  illustrating the inward camber  108 ,  110 ,  112  of bands  104 ,  106 ,  108  respectively, that may result from flexing the bands when the opposing edges of the bands are engaged according to a primary interlocking mechanism and a secondary interlocking mechanism to be discussed in detail below. 
         [0028]    Rotated by a motor  170  mounted on the base  78  via a chain drive or other appropriate linkage arrangement, the engagement rotor  156  comprises a helical thread  157  and is operable to extend or lower the mast  100  by engaging at least one row of angled drive slots  144  disposed along a center length of at least one of bands  102 ,  104 , and  106 . In the embodiment depicted in  FIG. 5 , engagement rotor  156  engages three slots  144  of each band to elevate and lower mast  100 . As engagement rotor  156  rotates, rotor  156  continually accepts the next slot  144  in an adjacent band. Alternatively, engagement rotor  156  may engage only one or some number of bands less than the number of bands extending the mast  100 . For example, in one embodiment, only one band may have angled drive slots  144  and the engagement rotor is configured to engage only the band comprising the angled slots  144 . 
         [0029]      FIG. 1  further illustrates a high limit switch  120  to provide a signal when the mast is fully extended and. Low limit switch  122  provides a signal when the mast is fully retracted. 
         [0030]      FIGS. 3 and 4  illustrate flexible band  102  of a set of three flexible bands  102 ,  104 , and  106  that when engaged, form mast  100 . Each band  102 ,  104 , and  106  includes two rows of spaced apart teeth  304  disposed along opposite edges of a flat middle body portion  318  of each band. Each tooth  304  on both sides of each band includes a crown portion wherein an upper projecting portion  310  (defined as that portion closest to a top of the mast  100 ), and a lower projecting portion  312 , both projecting portions bent approximately 20-25 degrees towards the adjacent band, to facilitate interlocking with the adjacent band. In order to ensure a compact storage of bands  102 ,  104 , and  106  on respective spool assembly  82 ,  84 , and  86  (see  FIG. 1 ), the length of teeth  304  are progressively longer starting from a bottom tooth  304  having a length L2, that corresponds to the bottom of mast  100 , towards the top of the mast  300  where a length L1 of an uppermost tooth  304  is longer than length L2. Based upon the progressively longer teeth  304 , overlapping layers of a band on a spool lay flat over the underlying layer, the tooth including the projecting portion  301  and  312  of an underlying layer of spooled band resting beneath the longer tooth of the above layer, thus allowing for compact spooling of the band. 
         [0031]    Because the bands are drawn together via helical thread  157 , at any point in time, the three bands  102 ,  104 , and  106  engage three different sections of the helical thread  157 . In order for the teeth  304  of adjacent bands to interlock, the teeth  304  on the three bands are differently placed, relative to the angled slot. Accordingly, the three bands  102 ,  104 , and  106  form a set, each of bands being unique and non-interchangeable with the other two bands to ensure that the three bands properly engage and interlock. 
         [0032]    The bands  102 ,  104 , and  106  are designed to provide a dual locking mechanism, comprising a primary locking mechanism and a secondary locking mechanism. The primary locking mechanism is based on each tooth  304  of each band interlocking between two teeth  304  of an adjacent band. Projecting portions  310  and  312  of each tooth  304  engage a notch  311  disposed at a base portion of an upper tooth  304  and a lower tooth  304 , respectively, an opposing band. In at least one embodiment, the notch  311  is semi-circular shaped. Once each tooth is locked between two opposing teeth, the notches provide an additional impediment preventing the teeth from separating. 
         [0033]    The secondary locking mechanism is provided by the engaging of a tab  306 , disposed between each of two adjacent teeth on one band, engaging a slot  308  disposed in the center of each opposing tooth  304  on an adjacent band. The tabs  306  and the slots  308  are shaped such that the edges of tab  306  bind within an inside edge of slot  308 . This dual locking mechanism advantageously minimizes twist and provides greater mast stability. 
         [0034]      FIG. 5  illustrates wherein mast  300  is formed by bands  102 ,  104 , and  106 , drawn together and upwards by the rotation of engagement rotor  156 , the helical thread  157  of rotor  156  engaging at least one angled slot  144  of each band. As described above, each tooth  304  of a band is locked between two teeth  304  of an adjacent band to form the primary lock. Each tab  106  disposed between two teeth  304  on a band engages a slot  308  disposed within tooth  304  of the adjacent band to form a secondary lock. 
         [0035]    Once the primary and secondary interlocks are engaged, the outward force created by the camber  108 ,  110 , and  112 , as depicted in  FIG. 2 , operates to maintain the rigidity of the mast  300 . 
         [0036]      FIG. 5  further depicts wherein a bottom portion of rotor  156  has a curved flange portion  158  that makes contact with the bands, guiding the bands  102 ,  104 , and  106  towards the threads  157  as the mast is extended, and facilitating separating the bands as the mast  100  is retracted. 
         [0037]      FIG. 5  further depicts an anti-sway device  300  disposed at the upper end of the mast  100  below platform  194  to apply tension on the interlocked bands via a pair of set screws  302  that apply pressure against each band. Thus, based on the primary and secondary interlocking mechanisms and the anti-sway device  300 , the mast  100  is sufficiently rigid for use in environments experiencing external forces such as vibration and wind. 
         [0038]    Bands  102 ,  104 , and  106  are designed to self-wind into spools  82 ,  84 , and  86  (see  FIG. 1 ) when the mast  300  is lowered. In one embodiment, the bands  102 ,  104 , and  106  are laser cut from 0.015-0.032 inch thick Type  301 , full hard, high yield stainless steel, which provides extra high strength and is able to resist the external forces that may operate to twist the mast, or cause the bands  302   a - c  to disengage. The bands are cut so that the direction of the steel bands runs along a lengthwise axis corresponding to a direction when unrolled from a roll of steel used to supply the band material. When cut from steel stock, taking into account the curvature of the supply roll, unrolling and rolling the band on the mast&#39;s spool assembly during operation of the mast is facilitated. 
         [0039]    Each band  102 ,  104 , and  106  is rolled to form a spool of a predetermined inside and outside diameter. The diameters are predetermined based upon the desired height of the mast and the condition that when coiled, teeth  304  are in radial alignment so as to lie flat against an underlying tooth of smaller length. The inner and outer diameters of the wound band  302  are maintained while the wound band  302  is heated for approximately 2-4 hours in an oven preheated to about 650-800 degrees Fahrenheit (preferably 3 hours in an oven preheated to about 700 degrees Fahrenheit), after which time the band  302  is removed and is cooled, e.g., air cooled in at least some embodiments. 
         [0040]    In at least one embodiment, each band may be composed of 0.025 inch thick Type  301 , full hard, high yield stainless steel. In other embodiments, the flexible bands may be made of a synthetic material, such as plastic, a flexible ceramic, or a composite material. 
         [0041]    Although the exemplary embodiments illustrated and discussed herein may comprise three bands, other embodiments may employ more bands based upon user specific operational requirements. 
         [0042]    Coaxial bore  88  is formed within the engagement rotor  156  and may permit at least one signal cable  98  to extend from cable pan  166  (see  FIG. 6A  and  FIG. 6B ) mounted within base  78  of the apparatus  10 , through a passageway formed by bands  102 ,  104 , and  106  through the length of the mast  100 . The at least one signal cable  98  may interconnect at least one device, i.e., camera/sensor  168 , mounted on top of platform  194  at the top of the mast  100  to components though a connector  167  disposed in an edge of cable pan  166 . 
         [0043]      FIG. 6A  depicts a cable  98  being drawn from cable pan  166  located at the bottom of base unit  78  as the mast  100  is extended. In one embodiment, cable  98  transmits power and communication signals from the base of the mast  100  to the one or more devices at the top of the mast  100  through the center of the mast  100 . The cable  98  is coiled on the bottom the cable pan  166 , one end of cable  98  being fixed to a stationary portion of cable pan  166 . The stationary portion may include a cable connector  167  that may be further connected to control module  162 , power module  172  and/or other devices supplying signals to or receiving signals from the mast mounted devices  168 . As the mast is extended, cable  98  is drawn from the cable pan  166 . The cable pan  166  includes a cable diverter  179  comprising a raised center point disposed in the center of a bottom of the cable pan  166 . 
         [0044]      FIG. 6B  depicts a cable  98  being coiled in a cable pan during retraction of mast  100 . When the mast  100  is retracted, cable  98  is lowered into the cable pan  166  and is guided by diverter  179  outwards from the center of the cable pan  166 . To facilitate extending a compact spiral of cable  98  within the cable pan  166 , surface  181  of cable pan  166  is inclined downward and away from the diverter  179  to allow the cable  98  to slide along the inclined surface  181  and form a spiral of coil cable  98 . 
         [0045]      FIG. 7  depicts a mechanism that allows for automatically stopping the extending or retracting of the mast.  FIG. 7  depicts upper limit switch  120  and lower limit switch  122  that provide signals when the mast  100  is fully extended, and fully retracted, respectively. Upper limit switch  120  is activated by a rotating member  802  that is rotated by operation of a contact rod  804  that is biased by a spring  806  to maintain contact rod  804  in contact with the outer layer of spooled band  102 . As the mast  100  is formed, band  102  is drawn from the spool, reducing the diameter of spooled band  102 , causing the contact rod  804  to rotate downward. Rotating member  802  follows the rotation of contact rod  804 . When an amount of spooled band  102  is reduced to a predetermined diameter such that the mast  100  is fully extended, rotating member  802  actuates the upper limit switch  120  and provides a signal over leads  66  to a control module  162  (see  FIG. 9 ). 
         [0046]    In one embodiment, lower limit switch  122  is activated by a rod  810  extending downward from a base plate, not shown, that is depressed by platform  194  as it is lowered. Upon activation, lower limit switch  120  provides a signal  67  indicating that the mast is in a fully retracted state. 
         [0047]      FIG. 8  is a block diagram illustrating the control logic for the lift mechanism  10  of  FIG. 1 . Control interface  164  provides a user with an interface to extend and retract the mast  100 . 
         [0048]    Control interface  164  is operated by a user to extend and retract the mast  100  and communicates with a control module  162  via a wired or wireless data link. 
         [0049]    Control module  162  may include an application-specific integrated circuit (“ASIC”), or other chipset, processor, logic circuit, or other data processing device. Control module  162  may also include memory, which may comprise volatile and nonvolatile memory such as read-only and/or random-access memory (RAM and ROM), EPROM, EEPROM, flash, or any memory common to computer devices. 
         [0050]    Control module  162  may further comprise logic that calculates the height of the mast  100  based upon a predetermined formula based upon a run time of the motor  170 . An indication of the mast height provided to the user may allow the user to extend the mast  100  to a user determined length/height, or may allow the control module  162  to extend the mast  100  to a predetermined height by controlling the activation time of the motor  170 . Furthermore, the control module  162  may comprise inputs and outputs  160  that may be connected to other lift mechanisms  10  so as to permit multiple lift mechanism  10  to operate in a master/slave relationship. For example, synchronizing the extending and retracting of a plurality of masts  100  to the same or to different heights based upon predetermined or user selectable inputs may be useful in situations requiring addition support, for example, to form a horizontal surface large enough to support the landing or take-off of an Unmanned Aerial Vehicle (UAV). 
         [0051]    Further still, control module  162  automatically stop extending mast  100  in response to a determination that the mast is fully extended based upon a signal received from high level limit switch  120 . Similarly, control module  162  may automatically stop lowering the mast  100  in response to a determination that the mast  100  is fully retracted based upon a signal received from low level limit switch  122 . 
         [0052]    Power module  172  may comprise any source of power suitable for use by the lift mechanism  10  and may include AC or DC inputs as well as AC and DC output capability. Non-limiting, the power module  172  may include a power cable to a source of AC power as well as NiMH and Li-ion rechargeable batteries. The power module  172  is operable to deliver required power to the control interface  164 , control module  162 , the lift motor(s)  170 , the devices on top of the mast  100 , as well as any other devices requiring electric power. 
         [0053]    In one embodiment, the controller module  162  and the power module  172  are mounted in a sealed center section of the base unit  78  above cable pan  166 . 
         [0054]      FIG. 9  illustrates one embodiment of an automatically deployable and retractable mast shield apparatus  174 . In certain environments, the mast  100  may be subject to potentially destructive material which may threaten proper operation of the lift mechanism. For example, rain may pass through openings in the mast  100  and potentially enter the base of the lift mechanism. Furthermore, dust or dirt may clog the slots and freezing rain may lock up the mast  100 . Accordingly, a mast shield apparatus  174  that operates to automatically surround the mast  100  as the mast is extended and automatically retracts when the mast is retracted may be beneficial. Furthermore, in some applications, e.g., trade shows, a mast shield apparatus having an esthetically pleasing covering is appropriate. 
         [0055]    In some embodiments, mast shield apparatus  174  includes a housing  171  that is mounted over a lift mechanism (not shown). In one embodiment the housing  171  includes three pairs of upright support members  173  mounted on a partially shown support surface  77 . Each pair of support members  173  is operable to support roller  176 , which comprises a spool of shield material  175  to shield each band  102 ,  104 , and  106 . In some embodiments, the shield material  175  is made of canvas, a synthetic material, or any suitable material, each shield material having a width larger than a width of the flexible bands that comprise the mast  100 . The shield material has a length to encompass the length of the mast  100 . Furthermore, a top portion of each length of shield material  175  is securely fastened to the top of the mast  100  or may be fastened to platform  194 . 
         [0056]    As the mast is extended, the attached shield material  175  is drawn from rollers  176 , causing the rollers  176  to rotate, applying tension to a spring (not shown) disposed within each roller  176 . Non-limiting, tensioned rollers are known to those of ordinary skill in the art, and any suitable spooling mechanism may be incorporated. 
         [0057]    In one embodiment, a retaining rail  181  is operable to align the shield material  175  in front of the mast  100 , at which point a guide mechanism  186  may operates to force the edges  178 ,  179  of the shield  175  together as the shield material is  175  are drawn off their respective spools  176 . Opposing edges  178 ,  179  of adjacent shields material sections may employ an attachment mechanism, e.g., Velcro, a plastic or metal zipper arrangement, or other known mechanism, to removably connect the sections of shield material  175  together as the mast is extended. As the mast is retracted, the tensioned rollers  176  winds up the shield material, causing the edges  178 ,  179  disengage after passing through the guide mechanism  186 . 
         [0058]      FIG. 10  illustrates a robotic lift apparatus  208  comprising the lift mechanism of  FIG. 1  incorporated within a robotic device  210 . Such a robotic lift apparatus  208  may be beneficial to military and law enforcement agencies in providing surveillance at different elevations. 
         [0059]    Mounted in a housing  210  equipped with a transport system, e.g., treads  214 , a mast  100  may be extended through an opening  218  in the housing  210 , raising a camera  168  and/or other devices, e.g., lamp  206  and microphone  192 , mounted on a platform  194 . A housing mounted antenna  190  and controller within the housing allows the robotic device and lift apparatus  208  to be operated wirelessly from a remote device. A power module (not shown) mounted within the housing  210  may comprise rechargeable batteries that may be recharged using an external mounted terminal  216 . Although treads  214  may be incorporated in the robot lift apparatus  208 , robots and robot drive units are known. Accordingly, the transport system may comprise wheels or any other available mechanism. 
         [0060]    While the foregoing disclosure shows illustrative embodiments, it should be noted that various changes and modifications could be made herein without departing from the scope of the described embodiments as defined by the appended claims. For example, the apparatus  10  may modified to extend a retractable mast in a downward or other direction based upon a specific application. 
         [0061]    Furthermore, although elements of the described embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.