Abstract:
According to another aspect of the present invention, an airship includes a plurality of connected segments and a controller that is adapted to dynamically control the movement of each of the plurality of segments relative to one another during flight of the airship.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present applications claims the benefit of provisional U.S. Patent Application No. 61/444,075 filed Feb. 17, 2011, the contents of which are hereby incorporated by reference in their entirety, 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention is directed to an airship and a method for controlling the airship, in particular an airship having a plurality of connected segments wherein the movement of segments relative to one another may be dynamically controlled. 
         [0004]    2. Description of the Background of the Invention 
         [0005]    A typical airship such as a blimp has a rigid outer envelope filled with a lifting gas such as helium, An airbag or ballonet disposed inside the envelope is used to provide vertical control of the airship and to provide ballast when the airship is aloft, in particular, air is evacuated from the ballonet to outside the airship to cause the airship to ascend and air is pumped into the ballonet to cause the airship to descend. Such an airship may include more than one ballonet to provide ballast and to control the nose-to-tail orientation of the airship. 
         [0006]    Because typical airships have rigid outer structures, such airships may not be maneuverable in weather conditions involving high winds and/or turbulent air. Further, high-speed crosswinds may damage the rigid airship. Therefore, such airships are generally operated on calm days or when high-speed winds are not expected. 
       SUMMARY OF THE INVENTION 
       [0007]    According to one aspect of the present invention, an airship includes head, body, and tail segments and a controller adapted to adjust the attitude of the body segment with respect to one of the head segment and the tail segment. 
         [0008]    According to another aspect of the present invention, an airship comprises a plurality of connected segments and a controller adapted to dynamically control the movement of each of the plurality of segments relative to one another during flight of the airship. 
         [0009]    According to another aspect of the present invention a method of operating an airship. The airship has a plurality of segments and a coupling between adjacent segments. The method includes the steps of receiving attitude information from each of the plurality of segments and adjusting the pressure inside each segment and the stiffness of the coupling between adjacent segments during flight of the airship in response to the attitude information. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a side view of an airship; 
           [0011]      FIGS. 2A and 2B  are additional side views of the airship of  FIG. 1 ; 
           [0012]      FIG. 3A  is a front view of a segment closer strap of the airship of  FIG. 1 ; 
           [0013]      FIG. 3B  is a front view of the inside of a segment controller module associated with the segment closer strap of  FIG. 3A ; 
           [0014]      FIG. 4  is a front view of a cross-section of an embodiment of a segment of the airship of  FIG. 1 ; 
           [0015]      FIG. 5  is a front view of a cross-section of another embodiment of a segment of the airship of  FIG. 1 ; 
           [0016]    FIG,  6  is a block diagram of a control system of the airship of  FIG. 1 ; 
           [0017]      FIG. 7  is a side view of a propulsion system of the airship of  FIG. 1 ; and 
           [0018]      FIG. 8  is a flowchart of the processing undertaken by an airship controller of FIG,  1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]      FIG. 1  is a side view of an airship  100  along a longitudinal axis thereof. The airship  100  comprises a head segment  102 , two body segments  104   a  and  104   b,  and a tail segment  108 . It should be apparent that other embodiments of the airship  100  may include more or fewer body segments  104 . 
         [0020]    The airship  100  includes an outer shell  110  that is a single bag divided into segments, wherein each segment has internal bags  112  described further herein below. At the coupling  113  between each pair of adjacent segments, that is between the segments  102  and  104   a,  segments  104   b  and  106 , and segments  104   b  and  108  is a segment closer strap  114  operated by a strap controller module  116  associated therewith. In addition, each segment  102 ,  104 , or  108  includes a sensor module  118 , a segment fill fan and valve assembly  120 , and a pressure sensor  122  associated with the outer shell  110  surrounding such segment. The sensor module  118  includes multiple instrument sensors including a magnetic compass, an inertial navigation sensor, and/or a three-axis position sensor. 
         [0021]    A segment controller  124  is disposed in each segment  102 ,  104 , or  108  that receives measurements from the sensor module  118  and the pressure sensor  122  disposed in such segment, serializes, and transmits such sensor measurements to an airship controller  126 . In addition, the segment controller  124  receives from the airship controller  126  signals to adjust the stiffness of the segment  102 ,  104 , or  108  and to increase or decrease the pressure inside the segment  102 ,  104 , or  108 . The airship controller  126  also controls a motor driven propulsion module  122  to propel the airship  100 . 
         [0022]    Each segment  102 ,  104 , or  108  of the airship  100  is able to move separately from segments adjacent thereto. The amount of movement is dynamically controlled by independently controlling the pressure inside such segment  102 ,  104 , or  108  and also by adjusting the stiffness of the coupling  113  between adjacent segments. Expanding or constricting the segment closer strap  114  at such coupling  113  increases or reduces the stiffness of such coupling  113 . As in the side view shown in  FIG. 2A , increasing the pressure inside the segments  102 ,  104 , and  108  and expanding the closer straps  114  between segments  102  and  104   a,    104   a,  and  104   b,  and  104   b  and  108  enables the airship to assume a rigid cigar shaped profile that reduces aerodynamic drag. Such a profile and rigid structure may enable the airship  100  to hover over a relatively fixed area or to be propelled forward in low wind conditions. 
         [0023]    In one embodiment a plurality of sleeve segments  115  are distributed along the circumference of the outer shell  110  at the coupling  113  between two adjacent segments. In a preferred embodiment such sleeve segments  115  are sewn to the outer shell, The segment closer strap  114  is disposed between such sleeve segments  115  and the outer shell  110 . The sleeve segments  115  aid to keep the segment closer strap positioned along the circumference of the outer shell  110 . Other ways of securing the segment closer strap  114  to the outer shell  110  will be apparent to those skilled in the art. 
         [0024]    Reducing the stiffness of the coupling  113  between adjacent segments by constricting the segment closer strap  114  at such coupling  113  and reducing the internal pressure in such segments allows the portion of the airship  100  that includes such segment to become flexible.  FIG. 2B  shows a side view of the airship wherein the diameters of the closer straps  114  and the internal pressures of the segments  102 ,  104 , and  108  have been adjusted to allow the airship  100  to become flexible. That is the segments  102 ,  104 , and  108  of the airship  100  are allowed to move with respect with one another. Further, it should be apparent that the diameters of the closer straps  114  between adjacent segments  102  and  104   a,    104   a  and  104   b,  and  104   b  and  108  do not have to be identical and therefore stiffness at the couplings  113  between such adjacent segments may vary. In high wind and/or turbulent air environments, such flexibility allows each segment  102 ,  104 , or  108  of the airship  100  to drift into a position that reduces the gradient of the wind with respect to such segment (that is, such segment presents a minimized cross-section to the wind), In this fashion, the airship  100  is able to remain airborne even in high wind and/or turbulent air conditions without being at risk of damage from crosswinds. 
         [0025]    The sensor module  118  disposed in each segment  102 ,  104 , or  108  of the airship  100  measures the direction in which such segment is facing and the attitude (e.g., pitch, yaw, and/or roll) of such segment. In addition, the pressure sensor  122  on the portion of the outer shell  110  associated with each segment  102 ,  104 , or  108  measures the internal pressure of such segment. Such pressure measurement provides an indication of the stiffness of the segment  102 ,  104 , or  108  where such measurement was obtained. 
         [0026]    Referring once again to  FIG. 1 , the segment controller  124  disposed on a segment  102 ,  104 , or  108  receives a signal from the airship controller  126  to adjust the pressure inside the outer shell  110  at such segment. In response, the segment controller  124  actuates the segment fill fan and valve assembly  120  to increase or decrease the pressure inside such segment by either drawing air from or exhausting air to, respectively, the atmosphere outside airship  100 . 
         [0027]    The segment controller  124  disposed on the segment  102 ,  104 , or  108  also receives a signal to adjust the segment closer strap  114  to either increase or decrease the stiffness of the coupling  113  between such segment and another segment adjacent thereto. In response, the segment controller  124  controls the strap controller module  116  to either tighten or loosen such segment closer strap  114 . 
         [0028]      FIG. 3A  is a front view of the segment closer strap  114  and the segment controller module  116  associated therewith.  FIG. 3B  is a front view of the inside of the segment controller module  116 . In one embodiment, one end  200  of the segment closer strap  114  is affixed to an inside wall  202  of the segment control module  116 . Another end  204  of the segment closer strap  114  is affixed to a strap winder  206 . The strap controller module  116  includes a reversible gear motor  208  actuated by the segment controller  116 . A first pulley wheel  210  is disposed on a rotatable shaft  212  of the reversible gear motor  208 . A second pulley wheel  214  is disposed on a rotatable shaft  216  of the strap winder  206 . A belt  218  couples the first pulley wheel  210  with the second pulley wheel  214 . When the shaft  212  of the motor  208  rotates, the first pulley wheel  210  also rotates and causes the belt  218  to rotate. Rotation of the belt  218  causes the second pulley wheel  214  to rotate in response and such rotation of the second pulley wheel  214  causes the strap winder  206  to rotate. Rotation of the strap winder  206  in this fashion can release or wind the strap  114  and thereby increase or decrease, respectively, the diameter of the strap at the coupling  113  between two segments. 
         [0029]      FIG. 4  is a front view of a cross-section of one embodiment of the segment  104  taken along the line A of FIG,  1 . It should be apparent that the interiors of the segments  102  and  108  are similar to the interior of the segment  104 . The segment closer strap  114  is sewn into the outer shell  110  such that compression or expansion of the segment closer strap  114  causes compression and expansion of the coupling  113  between segments. In some embodiments, a baffle  302  is attached to the outer shell  110  and provides a barrier between segments. 
         [0030]    The interior gasbag  112  is filled with a lifting gas through a fill tube  308 . Typically, the interior gasbag  112  is filled when the airship  100  is prepared for operation. A pressure sensor  315  disposed on the surface of the gasbag  112  is used to monitor the pressure of the gasbag  112  during filing. In one embodiment, the interior gasbag  112  is filled with enough lifting gas to provide the maximum lift and altitude expect for a flight. In some embodiments, the interior gasbag  112  may be overfilled by a predetermined amount. 
         [0031]    As noted above, the fill fan and valve assembly  120  draws air into or evacuates air from the space  310  between the inner wall  312  of the outer shell  110  and the outer wall  314  of the gasbag  112 . Such drawing in or evacuation of air allows the control of the buoyancy of the segment  104  to be controlled so that such segment lifts away from or drops toward the ground. The lifting gas in the interior gasbag  112  provides lift by displacing the heavier air in the space  310 . Compression of the lifting gas in the interior gasbag  112  increases the density thereof and reduces the amount of lift provided by the lifting gas. The density of the lifting gas in the interior gasbag  112  is controlled by increasing or decreasing the amount of air in the space  310  and thereby compressing or decompressing, respectively, the interior gasbag  112 . When the fan and valve assembly  120  is operated to draw air into the space  310 , the gasbag  112  is squeezed which effectively increases the pressure in the space  310  and the density of the lifting gas therein. Further, drawing air into the space  310  also increases the rigidity of the portion of the outer shell  110  at the segment  102 ,  104 , or  108  in which such gasbag  112  is disposed. In some embodiments, the desired rigidity of the outer shell  110  and the rigidity of the gasbag  112  are determined prior to flight and altering the rigidity of the outer shell  110  is used to control lift. 
         [0032]    In preparation for flight of one embodiment of the airship  100 , the interior gasbag  112  is filled with the lifting gas through the fill tube  308  causing the airship  100  to ascend. Air from outside of the airship  100  is drawn through the fan and valve assembly into a space  310  between an inner wall  312  of the outer shell  110  and an outer wall  314  of the gasbag  112 . Air is drawn into or removed from the space  310  as necessary until the airship  100  stabilizes at a desired altitude and attitude. During flight, the fan and valve assembly  310  are operated to maintain the airship  100  at a desired altitude and attitude. In this fashion, the space  310  provides ballast to control the altitude and attitude of the airship  100 . The amount of air in the space is also controlled to provide rigidity to the portion of the outer shell  110  associated with such segment. 
         [0033]      FIG. 5  is a front view of a cross-section of another embodiment of the segment  104  taken along the line B of  FIG. 1 . In this embodiment, two gasbags  112  and  316  are disposed for each segment  104  inside the outer shell  110  thereof. In particular, the gasbag  316  is disposed inside the gasbag  112 . The space  322  between the inner wall  318  of the gasbag  112  and outer wall  320  of the gasbag  316  is filled with air and the interior space  324  of the gasbag  316  is filled with lifting gas. During operation, the fill fan and valve assembly  120  is operated as described above to fill the space  310 . The amount of air drawn in or evacuated from space  310  determines the rigidity of the portion of the outer shell associated with the segment  104 . A fill tube  308  is provided to fill the space  322  with air and a fill tube  326  is provided to fill the space  324  with a lifting gas. The pressure sensor  315  is used to monitor the filling of the gasbag  112  and a second pressure sensor  328  is used to monitor the filling of the gasbag  316 . Drawing air into the space  310  by operating fan and valve assembly  120  also adjusts the pressure on the gasbag  112  and as therefore on the gasbag  316  that contains the lifting gas. In this manner, the altitude of the airship  100  may he controlled during flight as described above. 
         [0034]    An embodiment of the airship  100  that comprises a segment shown in  FIG. 5 , is prepared for flight by the space  324  with the lifting gas through the fill tube  326  causing the airship  100  to rise. As the airship begins to ascend and approach a desired altitude, air from the outside is drawn into the space  322  or released through the fill tube  308  until the airship  100  stabilizes at the desired height. The fill and valve assembly may also be operated as the airship  100  ascends to the desired altitude to draw air into the space  310  to provide additional control. 
         [0035]      FIG. 6  is a block diagram of the control system  400  of the airship. The control system comprises the airship controller  126  coupled to a pitot tube  402  and a Global Positioning System (GPS) module  404 . As described above, the airship controller  126  is coupled to each segment controller  116  associated with a segment  102 ,  104 , or  108 . The segment controller  116  transmits to the airship controller  126  readings from the sensor module  118  and the pressure sensor  122 . The airship controller  126  is also coupled to an autopilot unit  406  and a propulsion module  408 . 
         [0036]    The airship controller  126  monitors the readings from the pitot tube  402  and the GPS  404  module to manage the in-flight vector parameters, air speed, and to control the altitude and attitude of the airship. The airship controller  126  also communicates with the autopilot unit  406  and/or a ground controller in order to keep the airship  126  in a stationary position or to correctly travel to a predetermined location at a predetermined altitude. 
         [0037]    The airship controller  126  controls a propulsion module  408  to move the head segment  102  in a particular direction and control the attitude of such segment  102 . The airship controller  126  also monitors and adjusts the inflation pressure, the heading, and the attitude of each of the segments  102 ,  104 , and  108  to ensure that the remaining segments  104  and  108  of the airship follow the head segment  102  while minimizing the forces of the wind on the segments of the airship  100 . For example, in this manner, the airship controller  126  can guide the airship  100  through areas of heavy wind in a desired direction of travel while minimizing the forces of the wind on the segments of the airship  100 . The airship controller  126  controls the pitch of an individual segment  102 ,  104 , or  108  by increasing or decreasing pressure on the gasbag  112  or  320  in such segment to adjust the lift thereof. In addition, the airship controller  126  drives an individual segment  102 ,  104 , or  108  into a preferred orientation by opening or closing the segment closer straps  114  between such segment and segments adjacent thereto. 
         [0038]    The control system  400  includes power module  410  to provide electrical power to the components thereof. The power module  410  may be any suitable source of electrical energy including a battery, solar cell, wind generator, or a combination thereof. 
         [0039]      FIG. 7  is a side view of the propulsion module  408  of the airship  100 . The propulsion module  408  includes a propeller  700  coupled to a shaft  702  of a motor  704 . In one embodiment the propulsion module  408  also includes a starter motor  70 $ coupled to the motor  704  that assists in starting the motor  704 . In some embodiments the propulsion module  408  includes one or more mufflers  710  to dampen noise generated by the motor  704 . The motor  704  is attached to a gimbal  714 . The gimbal  714  is coupled to the airship controller  126  so that the airship controller can adjust the pitch and yaw of the motor  704  and thereby control the pitch and yaw of the head segment  102  of the airship  100 . 
         [0040]    In some embodiments, one or both of the motors  704  and  708  may be powered by combustion of a fuel such as a petroleum fuel. In such embodiments, a fuel tank  712  holds such fuel and is coupled to the motors  704  and/or  708  via fluid lines (not shown). Other types of energy sources known in the art may be used to power the motors  70 $ and  708  including solar, wind, a battery or a combination thereof. 
         [0041]    The gimbal  714  and the fuel tank  712  are secured to a pod frame  716 . A top rail support  714  attaches to the bottom of head segment  102  as shoe in  FIG. 1 . In one embodiment, reinforcing patches (not shown) are glued and sewn onto the portion of the outer shell  110  associated with the head segment  102 . Such reinforcing patches include nylon fabric loops to which the top rail  714  may be secured. The reinforcing patches are aligned in a longitudinal orientation along the centerline of the airship  100 . Additional transverse patches (not shown) may also be secured to the portion of the outer shell  110  associated with the head segment  102  to which the top rail support  714  may be secured by, for example, nylon ropes. Securing the top rail support  714  to the reinforcing patches and the transverse patches restricts side-to-side swaying of the pod frame  716 . 
         [0042]      FIG. 8  shows a flowchart of processing undertaken by the airship controller  126  to control the airship. A block  800  obtains the desired direction of travel from the autopilot  406  or from a ground control system (not shown). A block  802  uses information from the pitot tube  402  and the GPS  404  determine the current location, attitude, direction of travel of head segment  102  of airship  100 . A block  804  determines if the difference between the current direction of travel and the desired direction of travel warrants adjusting the direction in which the airship  100  is traveling. In some embodiments, the block  804  determines that such an adjustment is warranted if the difference between the desired and actual directions of travel is greater than a predetermined value. In a preferred embodiment, such difference is 15 degrees. 
         [0043]    if the block  804  determines that the direction in which the airship  100  is traveling or the attitude of the airship  100  should be modified, a block  806  determines if the attitude and direction of the head segment  102  should be adjusted. Otherwise, processing returns to the block  800 . 
         [0044]    The block  806  obtains sensor readings from the segment controller  124  associated with head segment  102  and analyzes such reading to determine the attitude and direction of such segment  102 . If the block  806  determines that the attitude and/or direction of the head segment  102  do not need to be adjusted, processing proceeds to a block  812 . Otherwise, a block  808  adjusts the direction of the head segment  102  by controlling the gimbal  714 . 
         [0045]    Thereafter, a block  810  directs the segment controller  124  to operate the segment fan and valve assembly  120  to adjust the pressure inside the outer shell  110  of the head segment  102 , and/or increase or decrease the pressure on the ballonets to adjust lift. If the orientation of the head segment  102  needs to be adjusted, the airship controller  126  instructs the segment controller  124  to increase or reduce the tension on the segment closer strap  114  between the head segment  102  and the first body segment  104  to drive the head segment  102  into a desired orientation. Thereafter processing proceeds to a block  812 . 
         [0046]    The block  812  obtains and analyzes the sensor data received from the body segments  104  and the tail segment  108  and determines if the orientation and attitude of such segments needs to be adjusted. If such adjustment is needed, a block  814  directs the segment controller  124  associated with each body segment  104  and the tail segment  108  to control the pressure inside such segment and to adjust the segment closer straps  114  between such segments as described above. After the block  814  processing proceeds to the block  800 . In addition, if the block  812  determines that no adjustments are necessary to the body and tail segments  104  and  108 , respectively, processing returns to the block  800 . 
         [0047]    The blocks of the flowchart shown in  FIG. 8  may be implemented by programming and/or by hardware and/or firmware as desired. Further, the airship controller may comprise computer executable code stored in a memory associated with the airship controller  126  that undertakes some or all of the blocks shown in the flowchart of  FIG. 8 . 
         [0048]    In a preferred embodiment, the outer shell  102  of the airship  100  is made of a ripstop nylon material. The gasbags  112  inside each segment  102 ,  104 , or  108  are made of Mylar® and helium is used as the lifting gas. In one embodiment the motor  704  in the propulsion system  408  is a Desert Aircraft DA-170 2 stroke mother that generates 17 horsepower and turns the propeller  700  that has two 36-inch blades. In another embodiment, the motor  704  is a Bailey Aviation 4V-200 4-stroke engine that produces 22 horsepower and the propeller  700  that has two or three 39-inch blades. 
       INDUSTRIAL APPLICABILITY 
       [0049]    Numerous modifications to the airship and method of controlling the same will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is presented for the purpose of enabling those skilled in the art to make and use an airship have individually controllable segments. The exclusive rights to all modifications which come within the scope of the appended claims are reserved.