Patent Publication Number: US-2022234761-A1

Title: Object lifting system and method

Description:
FIELD 
     This disclosure relates generally to lifting an object, and more particularly to a system and method for lifting an object from a sub-floor to an upper-floor. 
     BACKGROUND 
     The assembly of large structures, such as airplanes, is typically performed on a factory floor where parts are moved into installation positions to be installed to and partially form the large structure. In the case of an airplane, parts to be installed on the airplane, such as sub-assemblies of a fuselage, can be assembled together to form the fuselage in an assembly line. 
     A moving assembly line, such as a pulse line, can be utilized. In a pulse line, parts to be installed are positioned sequentially in a straight or U-shaped line on the factory floor. The parts stay at those positions while the large structure (e.g., an aircraft fuselage) is moved through the pulse line. The large structure will remain in one location along the pulse line until all the parts at that location are installed and other planned work is completed, then the large structure is moved (i.e. pulsed) to the next location. Existing solutions primarily use manual processes for locating, moving, and positioning of parts, which leads to long installation times and is labor intensive. Accordingly, the time and labor inefficiencies of manual processes can slowdown the assembly of large structures in the assembly line, which can result in rate requirements, such as for an aircraft fuselage assembly line, to be missed. 
     SUMMARY 
     The subject matter of the present application has been developed in response to the present state of the art, and in particular, in response to shortcomings of conventional installation and assembly processes and systems. Accordingly, the subject matter of the present application provides a system and method for lifting an object that overcome at least some of the above-discussed shortcomings of conventional processes and systems. 
     Disclosed herein is a system for lifting an object. The system comprises a first floor and a second floor. The first floor is directly above the second floor and securing an assembling body and the second floor. The system also comprises an object rack supported on the second floor. The object rack is configured to support a plurality of objects. The plurality of objects configured to be attached to the assembling body. The system further comprises an object advance apparatus coupled with the object rack. The object advance apparatus is configured to advance one object from the plurality of objects from an advancing position to a lifting position. The system additionally comprises a lifting cylinder supported by the second floor and positioned in line with the lifting position on the object rack. The lifting cylinder is configured to extend from a retracted position below the lifting position on the object rack to an extended position above the first floor, such that as the lifting cylinder is extended from the retracted position the one object in the lifting position is removed from the object rack and lifted adjacent to the assembling body. The system also comprises a floor flap in the first floor directly above the lifting cylinder. The floor flap is configured to open and close in synchronization with the extension and retraction of the lifting cylinder such that the floor flap is opened as the lifting cylinder is extended toward the first floor and remains opened while the lifting cylinder is in the extended position and is closed when the lifting cylinder is retracted below the first floor toward the retracted position and remains closed while the lifting cylinder is in the retracted position. The preceding subject matter of this paragraph characterizes example 1 of the present disclosure. 
     The system further comprises a conveyor system. The assembling body is secured to the conveyor system on the first floor, and the assembling body is moved along the conveyor system at a specified pulse rate. The preceding subject matter of this paragraph characterizes example 2 of the present disclosure, wherein example 2 also includes the subject matter according to example 1, above. 
     The assembling body is an aircraft fuselage. The preceding subject matter of this paragraph characterizes example 3 of the present disclosure, wherein example 3 also includes the subject matter according to any one of examples 1 or 2, above. 
     The plurality of objects is a plurality of frame sections to be attached to the aircraft fuselage. The preceding subject matter of this paragraph characterizes example 4 of the present disclosure, wherein example 4 also includes the subject matter according to example 3, above. 
     The system further comprises a user device in electrical communication with the lifting cylinder. The user device is selectively operable by an operator to extend and retract the lifting cylinder. The preceding subject matter of this paragraph characterizes example 5 of the present disclosure, wherein example 5 also includes the subject matter according to any one of examples 1-4, above. 
     The system further comprises a plurality of object racks. Each object rack of the plurality of object racks is configured to support a plurality of objects. The system also comprises an object advance apparatus coupled with each object rack of the plurality of object racks. Each one of the object advance apparatus is configured to advance one object from the plurality of objects of a corresponding one of the plurality of object racks from an advancing position to a lifting position. The system additionally comprises a plurality of lifting cylinders on the second floor. A corresponding one of the plurality of lifting cylinders is positioned in line with the lifting position on each object rack of the plurality of object racks. Each one of the plurality of lifting cylinders is configured to extend from the retracted position below the lifting position on the corresponding object rack to the extended position above the first floor, such that as the lifting cylinder is extended from the retracted position the one object in the lifting position is removed from the corresponding object rack and lifted adjacent to the assembling body secured to the first floor. The system further comprises a plurality of floor flaps in the first floor each directly above a corresponding one of the lifting cylinders of the plurality of lifting cylinders. Each floor flap configured to open and close in synchronization with the extension and retraction of the corresponding lifting cylinder, such that the floor flap is opened as the corresponding lifting cylinder is extended toward the first floor and remains opened while the corresponding lifting cylinder is in the extended position and is closed when the corresponding lifting cylinder is retracted below the first floor toward the retracted position and remains closed while the corresponding lifting cylinder is in the retracted position. The preceding subject matter of this paragraph characterizes example 6 of the present disclosure, wherein example 6 also includes the subject matter according to any one of examples 1-5, above. 
     The plurality of lifting cylinders is configured to automatically extend from the retracted position to the extended position and retract from the extended position to the retracted position at a specific rate. The plurality of cylinders is configured to extend and retract simultaneously. The object advance apparatus coupled with each object rack is configured to advance one object from the plurality of objects from the advancing position to the lifting position when the lifting cylinder is in the retracted position. The preceding subject matter of this paragraph characterizes example 7 of the present disclosure, wherein example 7 also includes the subject matter according to example 6, above. 
     The plurality of lifting cylinders is configured to automatically extend from the retracted position to the extended position and retract from the extended position at a specific rate. Each lifting cylinder of the plurality of lifting cylinders is configured to extend and retract consecutively with the other lifting cylinders of the plurality of lifting cylinders. The object advance apparatus connected to each object rack is configured to advance one object from the plurality of objects from the advancing position to the lifting position when the lifting cylinder is in the retracted position. The preceding subject matter of this paragraph characterizes example 8 of the present disclosure, wherein example 8 also includes the subject matter according to any one of examples 6-7, above. 
     Each lifting cylinder of the plurality of lifting cylinders is in electrical communication with a user device. The user device is selectively operable by an operator to extend from the retracted position to the extended position and retract from the extended position to the retracted position at least one lifting cylinder of the plurality. The preceding subject matter of this paragraph characterizes example 9 of the present disclosure, wherein example 9 also includes the subject matter according to any one of examples 6-8, above. 
     The object rack has a plurality of notches. Each object of the plurality of objects is supported on the object rack in engagement with a corresponding notch of the plurality of notches. The preceding subject matter of this paragraph characterizes example 10 of the present disclosure, wherein example 10 also includes the subject matter according to any one of examples 1-9, above. 
     Further disclosed herein is a system for lifting an object. The system comprises a first floor and a second floor. The first floor is directly above the second floor and securing an aircraft fuselage and the second floor supporting a plurality of frame racks. Each frame rack of the plurality is configured to support a plurality of frames. The plurality of frames is configured to be attached to the aircraft fuselage. The system also comprises a frame advance apparatus in connection with each frame rack of the plurality. The frame advance apparatus configured to advance one frame from the plurality of frames from an advancing position on each frame rack to a lifting position on each frame rack. The system further comprises a plurality of lifting cylinders supported by the second floor. One lifting cylinder of the plurality positioned is in line with the lifting position on a corresponding frame rack. Each lifting cylinder is configured to extend from a retracted position below the lifting position on the corresponding frame rack to an extended position above the first floor, such that as each lifting cylinder is extended from the retracted position the one frame in the lifting position is removed from the corresponding frame rack and lifted adjacent to the aircraft fuselage. The system additionally comprises a plurality of floor flaps. Each one of the plurality of floor flaps in the first floor is directly above a corresponding one of the plurality of lifting cylinders, the floor flaps are configured to open and close in synchronization with the extension and retraction of the corresponding lifting cylinder, such that the floor flaps are opened as the corresponding lifting cylinder is extended toward the first floor and remains opened while the lifting cylinder is in the extended position and are closed when the corresponding lifting cylinder is retracted below the first floor toward the retracted position and remains closed while in the corresponding lifting cylinder is in the retracted position. The preceding subject matter of this paragraph characterizes example 11 of the present disclosure. 
     Additionally disclosed herein is a method that comprises placing a plurality of objects on an object rack where the object rack is supported by a second floor, the second floor being directly below a first floor. The method also comprises advancing the plurality of objects with an object advance apparatus coupled with the object rack. One object of the plurality of objects advances from an advancing position to a lifting position. The method further comprises lifting the one object in the lifting position from the object rack with a lifting cylinder where the lifting cylinder is on the second floor and positioned in line with the lifting position on the object rack. The lifting cylinder extends from a retracted position below the lifting position on the object rack to an extended position above the first floor. The method additionally comprises opening a floor flap in the first floor directly above the lifting cylinder. The floor flap is in synchronization with the lifting cylinder, such that the floor flap opens as the lifting cylinder is extended toward the first floor and remains open while the lifting cylinder is in the extended position. The preceding subject matter of this paragraph characterizes example 12 of the present disclosure. 
     The method further comprises removing the one object from the lifting cylinder. The method also comprises retracting the lifting cylinder from the extended position to the retracted position. The method additionally comprises closing the floor flap as the lifting cylinder is retracted below the first floor towards the retracted position and remaining closed while the lifting cylinder is in the retracted position. The preceding subject matter of this paragraph characterizes example 13 of the present disclosure, wherein example 13 also includes the subject matter according to example 12, above. 
     The method further comprises advancing remaining objects of the plurality of objects. One object of the plurality of objects advances from the advancing position on the object rack to the lifting position on the object rack. The method also comprises lifting the one object in the lifting position from the object rack with the lifting cylinder. The lifting cylinder extends from the retracted position below the lifting position on the object rack to the extended position above the first floor. The method additionally comprises opening the floor flap in the first floor directly above the lifting cylinder. The floor flap is in synchronization with the lifting cylinder, such that the floor flap opens as the lifting cylinder is extended toward the first floor. The preceding subject matter of this paragraph characterizes example 14 of the present disclosure, wherein example 14 also includes the subject matter according to example 13, above. 
     The method further comprises removing the one object from the lifting cylinder by an operator on the first floor. The method also comprises installing the one object on an assembling body by the operator, the assembling body is secured to the first floor. The preceding subject matter of this paragraph characterizes example 15 of the present disclosure, wherein example 15 also includes the subject matter according to any one of examples 12-14, above. 
     The one object comprises a frame device. The assembly body comprises an aircraft fuselage. Installing the one object on the assembly body comprises installing the frame device to the aircraft fuselage. The preceding subject matter of this paragraph characterizes example 16 of the present disclosure, wherein example 16 also includes the subject matter according to example 15, above. 
     Placing a plurality of objects on an object rack comprises placing a plurality of objects on a plurality of object racks, such that each object rack of the plurality supports a plurality of objects. Advancing the plurality of objects with the object advance apparatus comprises advancing the plurality of objects on each object rack with an object advance apparatus coupled with each object rack. Lifting the one object in the lifting position from the object rack with a lifting cylinder comprises lifting the one object in the lifting position from at least one object rack of the plurality of object racks. Opening a floor flap in the first floor comprises opening a floor flap of a plurality of floor flaps in the first floor that is directly over the lifting cylinder that is extending to the extended position. The preceding subject matter of this paragraph characterizes example 17 of the present disclosure, wherein example 17 also includes the subject matter according to any one of examples 12-16, above. 
     Lifting the one object in the lifting position comprises lifting the one object in each lifting cylinder of the plurality of lifting cylinders simultaneously. The preceding subject matter of this paragraph characterizes example 18 of the present disclosure, wherein example 18 also includes the subject matter according to example 17, above. 
     Lifting the one object in the lifting position comprises lifting the one object in each lifting cylinder of the plurality of lifting cylinders consecutively. The preceding subject matter of this paragraph characterizes example 19 of the present disclosure, wherein example 19 also includes the subject matter according to any one of examples 17-18, above. 
     The method further comprises operating a user device in electrical communication with the plurality of lifting cylinders to lift at least one lifting cylinder of the plurality of lifting cylinders. The user device is selectively operable by an operator to extend and retract the lifting cylinders. The preceding subject matter of this paragraph characterizes example 20 of the present disclosure, wherein example 20 also includes the subject matter according to any one of examples 17-19, above. 
     The described features, structures, advantages, and/or characteristics of the subject matter of the present disclosure may be combined in any suitable manner in one or more examples and/or implementations. In the following description, numerous specific details are provided to impart a thorough understanding of examples of the subject matter of the present disclosure. One skilled in the relevant art will recognize that the subject matter of the present disclosure may be practiced without one or more of the specific features, details, components, materials, and/or methods of a particular example or implementation. In other instances, additional features and advantages may be recognized in certain examples and/or implementations that may not be present in all examples or implementations. Further, in some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the subject matter of the present disclosure. The features and advantages of the subject matter of the present disclosure will become more fully apparent from the following description and appended claims, or may be learned by the practice of the subject matter as set forth hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the advantages of the subject matter may be more readily understood, a more particular description of the subject matter briefly described above will be rendered by reference to specific examples that are illustrated in the appended drawings. Understanding that these drawings depict only typical examples of the subject matter, they are not therefore to be considered to be limiting of its scope. The subject matter will be described and explained with additional specificity and detail through the use of the drawings, in which: 
         FIG. 1  is a schematic perspective view of a system for lifting an object, according to one or more examples of the present disclosure; 
         FIG. 2  is a schematic perspective view of a lifting cylinder in an extended position, according to one or more examples of the present disclosure; 
         FIG. 3  is a schematic perspective view of an object rack with a lifting cylinder in an extended position, according to one or more examples of the present disclosure; 
         FIG. 4  is a schematic perspective view of an object rack, according to one or more examples of the present disclosure; 
         FIG. 5  is a schematic perspective view of a system for lifting an object to an aircraft fuselage, according to one or more examples of the present disclosure; 
         FIG. 6  is a schematic perspective view of an object rack, according to one or more examples of the present disclosure; and 
         FIG. 7  is a schematic flow diagram of a method of lifting an object, according to one or more examples of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference throughout this specification to “one example,” “an example,” or similar language means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example of the present disclosure. Appearances of the phrases “in one example,” “in an example,” and similar language throughout this specification may, but do not necessarily, all refer to the same example. Similarly, the use of the term “implementation” means an implementation having a particular feature, structure, or characteristic described in connection with one or more examples of the present disclosure, however, absent an express correlation to indicate otherwise, an implementation may be associated with one or more examples. 
     In some examples, the present disclosure provides systems and methods that are configured to lift an object adjacent to an assembling body for later installation of the object to the assembling body. Generally, the process of bringing an object adjacent to an assembling body for installing is a time-consuming, labor-intensive and manually-driven process. The systems and methods of the present invention can be used to make the process more automated and efficient by automatically lifting the object to be installed from a sub-floor adjacent to the assembling body. Accordingly, the systems and methods can be used to help to ensure an object is lifted adjacent to the area where the object is to be installed in a timely and labor efficient manner. In other words, the systems and methods are used for lifting and delivering objects to a point of use, and can be used within an assembly line. In one implementation, the lifting of objects on a lifting cylinder is synchronized with an object advancing system and floor flaps on a pulsed assembly line. 
     Referring to  FIG. 1 , and according to some examples, a system  100  for lifting an object is shown. The system  100  includes a first floor  102  and a second floor  104 . The first floor  102  is directly above the second floor  104 . In one example, the first floor  102  is at ground level and the second floor  104  is below ground level. In other examples, the second floor  104  is at ground level and the first floor  102  is above ground level. It is not necessary for the first floor  102  and the second floor  104  to have the same dimensions (i.e. width or length). Rather, it is necessary for the second floor  104  to be directly beneath the first floor  102  so that objects can be lifted vertically from an original location supported by the second floor  104  to a secondary location directly vertically in-line with the original location above the first floor  102 . 
     An assembling body  106  is secured to the first floor  102 . In one example, the assembling body  106  is secured directly to the first floor  102 . In other words, the assembling body  106  is fixed to the first floor  102  and does not move relative to the first floor  102 , while the system  100  facilitates assembly of an object or objects to the assembling body  106 . Such direct securing could be through bolting or otherwise fastening the assembling body  106  to the first floor  102 . In other examples, the assembling body  106  is secured indirectly to the first floor  102 , and may be fixed or movable along the first floor  102 . For example, the assembling body  106  may move along the first floor  102  by being secured to a conveyor system  132  that is secured to the first floor  102 . The conveyor system  132  may be used to move the assembling body  106  through an assembly line while the assembling body  106  is being assembled. In one example, the assembly line is a pulse line, where the assembling body  106  remains at a location shown in  FIG. 1  during the lifting and installation of objects and other necessary work and then is pulsed to the next location along the assembly line. The lifting and installation of objects using the system  100  improves the efficiency over more manual processes. 
     The assembling body  106  is a large structure that is in the process of being assembled (e.g., not yet in a finalized state). The assembling body  106  may be any shape or size. In one example, only an interior surface of the assembling body  106  is accessible for an object to be installed to the assembling body  106 . One such example is an aircraft fuselage  134 , where objects are lifting into the interior of a half barrel of the aircraft fuselage  134 . In other examples, both an exterior surface and an interior surface of the assembling body  106  are accessible and an object can be installed to either surface of the assembling body  106 . 
     The system  100  further includes an object rack  108  that is supported on the second floor  104 . The object rack  108  may be fixed to the second floor  104  or may be moveable about the second floor  104 . The object rack supports a plurality of objects  110 . In one example, the plurality of objects  110  are identical objects having the same size, shape, weight etc. In another example, the plurality of objects  110  may vary in size, shape, weight, etc. as long as the differing objects are capable of being lifted by a lifting cylinder as described below. 
     The system  100  further includes a lifting cylinder  120  that is also supported on the second floor  104 . In one example, the lifting cylinder  120  is separate from the object rack  108 . In another example, the lifting cylinder is attached to or integrally formed to the object rack  108 . The lifting cylinder  120  is positioned in line with a lifting position  118  (see, e.g.,  FIG. 3 ) on the object rack  108 . Accordingly, the lifting cylinder  120  is configured to extend and retract vertically in line with the lifting position  118 . As shown in  FIG. 1 , an object  112  of the plurality of objects  110  is being lifted from the object rack  108  by the lifting cylinder  120 . 
     Referring to  FIG. 2 , the lifting cylinder  120  is configured to move vertically from the second floor  104  to an extended position  126  above the first floor  102 . The lifting cylinder  120  lifts the object  112  adjacent to the assembling body  106 . In one example, the extended position  126  is at a location that is accessible and ergonomic for an operator  138  to pick up the object  112 . 
     As shown in  FIG. 2 , the system  100  further includes a floor flap  128  that is located or formed in the first floor  102 . The floor flap  128  is attached to the first floor  102  and is used to expose or cover an opening  127  in the first floor  102 . The opening  127  is sized such that the lifting cylinder  120  and the object  112  can be extended though the opening  127 . The floor flap  128  is sized to cover the opening  127  in the first floor  128 . In one example, the floor flap  128  includes one piece of material attached to one side of the opening  127 . In another example, the floor flap  128  includes two pieces of material, each piece attached at opposite sides of the opening  127 . The floor flap  128 , when open, is generally perpendicular, or greater than perpendicular, relative to the first floor  128  to allow the lifting cylinder  120  to extend through the opening  127  without contacting the floor flap  128 . Although not shown, the floor flap  128  is actuated by an electronically-controllable actuator, such as a pneumatic or hydraulic cylinder or motor. 
     The floor flap  128  opens and closes in synchronization with the extension and retraction of the lifting cylinder  120 . The floor flap  128  opens as the lifting cylinder  120  is extended toward the first floor  102  and will remain open while the lifting cylinder  120  is in the extended position  126 . The floor flap  128  closes as the lifting cylinder  120  is extended below the first floor  102  and remains closed while the lifting cylinder  120  is in the retracted position  124 . If the floor flap  128  is of sufficient strength it can also be used to prevent a moving object, such the operator  128  or a cart from falling into the opening  127 . 
     As shown in  FIGS. 3 and 4 , the lifting cylinder  120  moves vertically in line with the lifting position  118  on the object rack  108 . At its lowest vertical position, the lifting cylinder  120  is in the retracted position  124  below the lifting position  118  on the object rack  108 . At its highest vertical position, the lifting cylinder  120  is in the extended position  126  (see, e.g.,  FIG. 2 ) above the first floor  102 . The lifting cylinder  120  extends and retracts between the retracted position  124  and the extended position  126  to lift an abject from the object rack  108  to an intermediate location adjacent to the assembling body  106 . Specifically, the lifting cylinder  120  extends from the retracted position  124  and lifts one object  112  in the lifting position  118  from the object rack  108 , and continues to extend to the extended position  126  above the first floor  102 . In this position, an operator  138  (see, e.g.,  FIG. 2 ) on the first floor  102  may remove the one object  112  from the lifting cylinder  120  for installation to the assembling body  106 . 
     As shown in  FIG. 3 , in one example, the object rack  108  includes a plurality of notches  142 . The notches  142  are sized to matingly engage corresponding features of a corresponding object  112  of the plurality of objects  110 . Accordingly, each notch  142  supports a corresponding object  112  of the plurality of objects  110 , and the corresponding object  112  remains engaged with the corresponding notch  142  until the corresponding object  112  is lifted from the object rack  108  by the lifting cylinder  120 . 
     The system  100  additionally includes an object advance apparatus  114  that is coupleable with the object rack  108  to advance the object rack  108  relative to the lifting cylinders  120 . Accordingly, the object advance apparatus  114  is configured to advance the object rack  108  along the second surface  104 , and relative to the lifting cylinders  120 , such that the objects  112  of the plurality of objects  110  advance one-by-one from an advancing position  116 , horizontally away from, any one of the lifting cylinders  120  to a lifting position  118 , vertically above one of the lifting cylinders  120 . The object advance apparatus  114  advances the object rack  108  in a cyclical pattern, moving one object at a time from the advancing position  116  to the lifting position  118 . 
     In some examples, multiple object racks  108  are used to lift objects, with each object rack  108  supporting a plurality of objects  110 . Multiple object racks  108  may be used to increase the rate at which objects are lifted by the lifting cylinders  120 . Additionally or alternatively, a specific lifting cylinder  120  can be utilized to lift an object to a specific location adjacent to the assembling body  106 . 
     At least one lifting cylinder  120  is associated with each object rack  108  and positioned in line with the lifting position  118  on each object rack  108 . However, at shown in  FIG. 3 , multiple lifting cylinders  120  are associated with each object rack  108  such that multiple objects from the same rack can be lifted synchronously from the same object rack  108  by multiple lifting cylinders  120 . Each lifting cylinder  120  can be configured to automatically extend from the retracted position  124  to the extended position  126  and retract from the extended position  126  to the retracted position  124  at a specific rate. In one example, each lifting cylinder  120  is configured to extend and retract simultaneously with the other lifting cylinders  120 . In another example, each lifting cylinder  120  is configured to extend and retract consecutively with the other lifting cylinders  120 . In yet another example, a user device  136  can be selectively operable by the operator  138  to extend and retract at least one lifting cylinder  120 . 
     Referring to  FIGS. 5-6 , a system  200  similar to the system  100  can be used to bring aircraft fuselage frames  210  to an aircraft fuselage  206 . The system  200  includes a first floor  202  that is directly upon a second floor  204 . The fuselage  206  is in the process of being assembled and is secured to the first floor  202 . The fuselage  206  is indirectly secured to the first floor  202  by being secured to a conveyor system  232 , the conveyor system  232  moveably secured to the first floor  202 . The conveyor system  232  is used to move the fuselage  206  through an assembly line while the fuselage  206  is assembled. 
     The system  200  includes a plurality of frame racks  208  that are supported by the second floor  204 . Each frame rack  208  supports a plurality of frames  210 . In one example, the plurality of frames  210  are all identical frames. In other examples, the plurality of frames  210  may vary in size, shape, weight, etc. The system  100  includes a plurality of lifting cylinders  220  that are also supported by the second floor  204 , with one lifting cylinder  220  associated with each frame rack  208 . The lifting cylinders  220  are separate from the frame rack  208  and the frame rack  208  is configured to move along the second floor  204  relative to the lifting cylinder  220 . The lifting cylinders  220  are positioned in line with lifting positions  218  on the frame rack  208 . Accordingly, the lifting cylinders  220  are configured to extend and retract vertically in line with the lifting positions  218 . As shown in  FIG. 5 , one frame  212  is being lifted from the frame rack  208  by one lifting cylinder  220  of the plurality of lifting cylinders  220 . Such lifting cylinder  220  is in an extended position  226 . 
     The system  200  further includes multiple floor flaps  228  that are located in the first floor  202 . Each floor flap  228  is attached to the first floor  202  and used to expose or cover an opening  227  in the first floor  202 . Each floor flap  228  corresponds with a lifting cylinder  220  that is directly beneath the floor flap  228  on the second floor  204 . Each floor flap  228  opens and closes in synchronization with the extension and retraction of the corresponding lifting cylinder  220 . The floor flap  228  opens as the corresponding lifting cylinder  220  is extended toward the first floor  202  and remains open while the corresponding lifting cylinder  220  is in the extended position  226 . The floor flap  228  closes as the corresponding lifting cylinder  220  is extended below the first floor  202  and remains closed while the corresponding lifting cylinder  220  is in the retracted position  224 . 
     The system  200  also includes a frame advance apparatus  214  that is coupled with each frame rack  208 . Each frame advance apparatus  214  is configured to advance the frame rack  208 , one frame  212  at a time, from an advancing position  216  to the lifting position  218 . The frame advance apparatus  214  advances the frame rack  208  in a cyclical pattern, moving one frame from the advancing position  216  to the lifting position  218  at a time. 
     In one implementation, the system  200  provides an efficient means of lifting frames into the fuselage  206  on a pulsed assembly line, and bringing the frames to the point of assembly. The lifting and delivery of frames is coordinated with fuselage movement along the pulsed assembly line. 
     Referring to  FIG. 7 , according to one example, a method  300  of lifting an object includes (block  302 ) placing a plurality of objects  110  on an object rack  108 . The object rack  108  is supported by a second floor  104 , the second floor  104  being directly below a first floor  102 . The method  300  also includes (block  304 ) advancing the plurality of objects  110  with an object advance apparatus  114  in connection with the object racks. The one object  112  of the plurality of objects  110  advances from an advancing position  116  to a lifting position  118 . The method further includes (block  306 ) lifting the one object  112  in the lifting position  120  from the object rack  108  with a lifting cylinder  120 . The lifting cylinder  120  is on the second floor  104  and positioned in line with the lifting position  118  on the object rack  108 . The lifting cylinder  120  extends from a retracted position  124  below the lifting position  118  on the object rack  108  to an extended position  126  above the first floor  102 . The method  300  additionally includes (block  308 ) opening a floor flap  128  in the first floor  102  directly above the lifting cylinder  120 . The floor flap  128  is synchronized with the lifting cylinder  120 , such that the floor flap  128  opens as the lifting cylinder  120  is extended toward the first floor  102  and remains open while the lifting cylinder  120  in in the extended position  126 . 
     In the above description, certain terms may be used such as “up,” “down,” “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,” “over,” “under” and the like. These terms are used, where applicable, to provide some clarity of description when dealing with relative relationships. But, these terms are not intended to imply absolute relationships, positions, and/or orientations. For example, with respect to an object, an “upper” surface can become a “lower” surface simply by turning the object over. Nevertheless, it is still the same object. Further, the terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise. Further, the term “plurality” can be defined as “at least two.” Moreover, unless otherwise noted, as defined herein a plurality of particular features does not necessarily mean every particular feature of an entire set or class of the particular features. 
     Additionally, instances in this specification where one element is “coupled” to another element can include direct and indirect coupling. Direct coupling can be defined as one element coupled to and in some contact with another element. Indirect coupling can be defined as coupling between two elements not in direct contact with each other, but having one or more additional elements between the coupled elements. Further, as used herein, securing one element to another element can include direct securing and indirect securing. Additionally, as used herein, “adjacent” does not necessarily denote contact. For example, one element can be adjacent another element without being in contact with that element. 
     As used herein, the phrase “at least one of”, when used with a list of items, means different combinations of one or more of the listed items may be used and only one of the items in the list may be needed. The item may be a particular object, thing, or category. In other words, “at least one of” means any combination of items or number of items may be used from the list, but not all of the items in the list may be required. For example, “at least one of item A, item B, and item C” may mean item A; item A and item B; item B; item A, item B, and item C; or item B and item C. In some cases, “at least one of item A, item B, and item C” may mean, for example, without limitation, two of item A, one of item B, and ten of item C; four of item B and seven of item C; or some other suitable combination. 
     Unless otherwise indicated, the terms “first,” “second,” etc. are used herein merely as labels, and are not intended to impose ordinal, positional, or hierarchical requirements on the items to which these terms refer. Moreover, reference to, e.g., a “second” item does not require or preclude the existence of, e.g., a “first” or lower-numbered item, and/or, e.g., a “third” or higher-numbered item. 
     As used herein, a system, apparatus, structure, article, element, component, or hardware “configured to” perform a specified function is indeed capable of performing the specified function without any alteration, rather than merely having potential to perform the specified function after further modification. In other words, the system, apparatus, structure, article, element, component, or hardware “configured to” perform a specified function is specifically selected, created, implemented, utilized, programmed, and/or designed for the purpose of performing the specified function. As used herein, “configured to” denotes existing characteristics of a system, apparatus, structure, article, element, component, or hardware which enable the system, apparatus, structure, article, element, component, or hardware to perform the specified function without further modification. For purposes of this disclosure, a system, apparatus, structure, article, element, component, or hardware described as being “configured to” perform a particular function may additionally or alternatively be described as being “adapted to” and/or as being “operative to” perform that function. 
     The schematic flow chart diagrams included herein are generally set forth as logical flow chart diagrams. As such, the depicted order and labeled steps are indicative of one example of the presented method. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the illustrated method. Additionally, the format and symbols employed are provided to explain the logical steps of the method and are understood not to limit the scope of the method. Although various arrow types and line types may be employed in the flow chart diagrams, they are understood not to limit the scope of the corresponding method. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the method. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted method. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown. 
     The present subject matter may be embodied in other specific forms without departing from its spirit or essential characteristics. The described examples are to be considered in all respects only as illustrative and not restrictive. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.