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FIELD 
     The present embodiments generally relate to a tensioner assembly that can provide a highly accurate and highly reliable determination of the location of a cylinder rod in a tensioner assembly, such as during withdrawal or extension of the cylinder rod from the cylinder. 
     BACKGROUND 
     A need exists for an accurate tensioner assembly that can determine the position of a piston portion of a cylinder rod with an accuracy of 0.01 of an inch. 
     A further need exists for a rugged seaworthy tensioner assembly that can be used for supporting oil platforms and that can accurately detect the location of the cylinder rod, thereby preventing oil spills, tilting of the platform, and accidents on offshore oil rigs. 
     The present embodiments meet these needs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description will be better understood in conjunction with the accompanying drawings as follows: 
         FIG. 1  is a side view of a pressure containing tube for tensioning a structure. 
         FIG. 2  is a cross sectional view of the pressure containing. 
         FIG. 3A  is a detail of a laser controller. 
         FIG. 3B  is a detail of a camera. 
         FIG. 4  is a detail of the main controller. 
         FIG. 5  is a cross sectional view of an optic guide. 
         FIG. 6  is a perspective view of a blind end cap and mount. 
         FIG. 7  is a diagram of a method for determining a position of a rod in a cylinder stroke system. 
         FIG. 8  is a perspective view of the tensioner assembly. 
         FIG. 9  is a detail of a fluid source controller. 
     
    
    
     The present embodiments are detailed below with reference to the listed Figures. 
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Before explaining the present assembly and method in detail, it is to be understood that the assembly and method are not limited to the particular embodiments and that the assembly and method can be practiced or carried out in various ways. 
     The present embodiments relate to a tensioner assembly. The tensioner assembly can include or can use a pressure containing tube with a first tube end and a second tube end. 
     One or more embodiments of the tensioner assembly can include a plurality of cylinder stroke systems. 
     A first fluid source regulator can control or regulate fluid flow from a first fluid source to each of the cylinder stroke systems. The first fluid source regulator can be a valve, a pump, or another fluid flow regulator. 
     A fluid source controller can control the first fluid source regulator. The fluid source controller can include a fluid flow processor. The fluid flow processor can be in communication with a fluid source data storage. The fluid source data storage can have computer instructions to regulate the flow of a first fluid to and from a plurality of connected accumulators based on preset stroke limits for each cylinder rod in each pressure containing tube. The plurality of accumulators can be connected in series. 
     A gas source can be connected to the first fluid source. The gas source can be one or more tanks of inert gas. For example, the gas source can be a plurality of gas cylinders connected in series. 
     A gas source regulator can be connected between the first fluid source and the gas source. The gas source regulator can control or regulate gas flow from the gas source to at least one of the plurality of accumulators. The gas source regulator can be a valve. 
     In one or more embodiments, each cylinder stroke system can include a pressure containing tube. The pressure containing tube can have a first tube end and a second tube end. A cylinder rod can be movably disposed within the pressure containing tube. Each cylinder rod can have a cylinder rod first end and a cylinder rod second end. 
     Each cylinder stroke system can also include a piston. The piston can be disposed on the cylinder rod first end. The piston can have an outer diameter providing a sliding fit with an inner diameter of the pressure containing tube. The piston can be fixed to the cylinder rod. 
     A first fluid port can be formed in each pressure containing tube. The first fluid port can be in fluid communication with the first fluid source and can provide a first fluid to the pressure containing tube adjacent to the cylinder rod. In one or more embodiments the first fluid source can include a plurality of connected accumulators. A second fluid can be disposed within each pressure containing tube. 
     Each cylinder stroke system can include a blind end cap and mount. The blind end cap and mount can have a cap portion connected to the first tube end. The blind end cap and mount can have a mount portion connected to the cap portion. In one or more embodiments the mount portion can connect to a component of a floating vessel linked to a subsea well. 
     Each cylinder stroke system can include a laser, which can be secured to the pressure containing tube. The laser can be in communication with a laser controller. The laser can generate a beam. The beam can be reflected by another portion of the cylinder stroke system. For example, the beam can be reflected by the piston. 
     At least one optic guide can be disposed through the first tube end. The optic guide can be used to direct the beam from the laser through the second fluid to contact the piston. A lens can separate the optic guide from the second fluid. A pressure isolation flange can be used to connect the optic guide to the laser. 
     The laser controller can be in communication with a camera. In one or more embodiments, the camera can be in communication with a main controller in lieu of or in conjunction with the laser controller. The camera can capture the reflection of the beam from the piston and can convert the reflection into a reflection signal. The reflection signal can be transmitted to the main controller to determine a position of the cylinder rod in the pressure containing tube. The position of the cylinder rod can be determined with an accuracy from about 0.1 percent to about 2 percent of at least one calibration baseline of the beam in view of any particulate or oil buildup on the lens or in the second fluid. 
     The pressure containing tube can have a length from about 1 meter to about 30 meters, and an inner diameter from about 0.1 meter to about 0.8 meters. 
     A cylinder rod can move in and out of one side of the pressure containing tube. The cylinder rod can have a cylinder rod first end and a cylinder rod second end. In embodiments, the cylinder rod can be a hollow steel tube. 
     The cylinder rod can have an outer diameter in proportion to the length of the pressure containing tube that can range from about 1:60 rod diameter to tube length to about 1:24 rod diameter to tube length. The length of the cylinder rod can be from about 40 percent to about 60 percent the overall length of the pressure containing tube. 
     A cylinder head can connect to the second tube end and can allow the cylinder rod to moveably pass through the cylinder head. 
     A cylinder head seal can be disposed adjacent the cylinder head within the pressure containing tube, for sealing any fluid disposed in the pressure containing tube around the cylinder rod in the tube, preventing any leakage. The cylinder head seal can be formed in part from an elastomeric material, a synthetic rubber, a natural rubber, a metal, or combinations thereof. For example, the cylinder head seal can be a rubber coated metal disc. 
     The piston can be disposed on the cylinder rod first end to provide a barrier between the first fluid in the pressure containing tube and the second fluid in the pressure containing tube, thereby isolating the second fluid from the first fluid. 
     A first fluid port can allow the first fluid to flow from a first fluid source, such as a tank, into the pressure containing tube. This first fluid can flow into the pressure containing tube and around the cylinder rod. 
     The second fluid can be disposed within the pressure containing tube on the side of the pressure containing tube opposite the side containing the cylinder rod. The second fluid can be isolated from the first fluid by the piston. 
     The first fluid can be a hydraulic fluid, a hydraulic oil, air, or an inert gas. The second fluid can be compressible, such as a gas or a vapor, or an inert gas, such as nitrogen, helium, or argon. 
     A blind end cap and mount can be affixed to the first tube end. The blind end cap and mount can have two components, including a cap portion having a hole for mounting and a mount portion attached to the cap portion. The mount portion can engage the first tube end. In embodiments, the mount portion can have a diameter larger than the cap portion. In embodiments, the blind end cap and mount can be a one-piece construction made from a rigid and durable material, such as steel. 
     A laser can be mounted to the pressure containing tube. The laser can be use to generate a beam. A camera can be mounted adjacent to the laser. The laser and the camera can be protected by a laser housing for resistance to impacts and water. In embodiments, the laser can be mounted parallel to the pressure containing tube. 
     The laser can produce a beam that can pass through at least one optic guide. In embodiments, three optic guides can be used along with the second fluid of the pressure containing tube to provide contact of the beam with the piston and to cause a reflection that can be captured by the camera. The reflection can pass back through the optic guides to the camera. 
     The camera can be in communication with a main controller, a laser controller, or combinations thereof. The camera can convert the reflection into a reflection signal, which can be transferred to the main controller. 
     The main controller and/or the laser controller can include computer instructions to determine a position of the cylinder rod in the pressure containing tube with an accuracy between 0.1 percent to 2 percent of at least one calibration baseline of the beam in view of any particulate or oil buildup on the lens or in the second fluid. 
     The laser controller can adjust the beam in view of preset data for the cylinder rod and can change the beam to improve accuracy of the reflection signal. The preset data can be a plurality of preset velocities. 
     At least one optic guide can be disposed through the cap portion for directing the beam from the laser through the second fluid to contact the piston and cause the reflection. 
     A lens can be used at the end of the optic guide adjacent the second fluid, thereby separating the optic guide from the second fluid. 
     In embodiments, the laser housing can be disposed about the laser and the camera. The laser housing can be formed from steel, a reinforced composite, or a polymer to provide water-resistance and explosion-resistance for the laser and the camera. The laser housing can have water resistant at depths up to 30 meters under water. 
     The laser housing can have an interface plug for connecting the laser and the camera in the housing with the main controller. 
     The main controller can have computer instructions in a data storage for instructing a processor to compare the reflection signal to a preset velocity and to use cylinder rod data in the data storage to determine a position of the cylinder rod in the stroke cycle relative to the pressure containing tube. 
     The optic guide or plurality of optic guides can each be at least partially contained within an optic guide housing. The optic guide housing can be disposed about the optic guide. At least part of the optic guide can be disposed in the mount of the blind end cap and mount. At least part of the optic guide can be external to the pressure containing tube. 
     A first optic guide can guide the beam from the laser to a first redirectional surface. The first re-directional surface can be a mirror, a prism, a reflective plate, or another surface that can redirect the beam at an angle, such as a 90 degree angle. 
     A second optic guide can then direct the re-directed beam to a second redirectional surface, which can be a prism, mirror, reflective plate, reflective lens, steel plate, gold coated plastic plate, or a similar material. The second optic guide can accurately redirect the laser beam at an angle, such as an angle from about 120 degrees to about 60 degrees. 
     The optic guides can have different diameters. The diameter of each optic guide can be wide enough to accommodate the beam, such as a diameter from about 12 mm to about 75 mm. 
     The twice redirected beam can be guided through a third optic guide to a lens, which can be supported by a lens retainer and encircled by a vapor diverter. The vapor diverter can be attached around one of the optic guides adjacent the lens for receiving any particles suspended in the second fluid. 
     The twice re-directed beam can enter the second fluid and contact the piston, which forms the reflection. The reflection can pass back through the lens, through the redirectional surfaces and optic guides, and to the camera adjacent the laser. 
     In embodiments, the camera can be spaced apart from the laser. For example, the camera can be disposed proximate to the lens. 
     In one or more embodiments, at least one re-directional surface can be disposed between any two optic guides. 
     In one or more embodiments, the beam can have a constant frequency that can be calibrated using a harmonic diagnostic procedure that can adjust to a composition of the second fluid. For example, the beam can have a constant frequency that can be calibrated using computer instructions for providing harmonic diagnostic procedures that adjust to a composition of the second fluid. The computer instructions can be stored in the laser controller. 
     The main controller can have a power supply, such as a rechargeable battery supply or a connection to a reliable 110 volt source. The main controller con have a user interface display connected to the power supply, a circuit board connected to the user interface display and the power supply, and a processor connected to the circuit board. 
     The main controller can have a data storage in communication with the processor. The data storage can have computer instructions to compare a current value representing the reflection to a preset value associated with a stroke distance for the cylinder rod in the pressure containing tube to determine a position of the piston in the pressure containing tube. Additional computer instructions within the main controller can be used for comparing the reflection signal to preset velocities for the cylinder rod. 
     One or more embodiments relate to a method for tensioning an offshore platform by using a cylinder stroke system with a laser proximity detector. 
     The method can include calibrating the laser to determine a limit of a fully extended cylinder rod in a pressure containing tube of a cylinder stroke system. 
     Next, the laser can be calibrated to determine a limit of a fully retracted cylinder rod in the pressure containing tube. 
     After calibration, a beam can be projected from the laser through at least one optic guide and through a lens to a piston connected to the cylinder rod. The beam, upon contacting the piston, can form a reflection, which can travel back through the lens and optic guide to a camera associated with the laser. The camera can convert the reflection to a reflection signal, which is also termed herein a “current value”. The camera can transmit the current value to the main controller. 
     The method can include using computer instructions in a data storage of the main controller to instruct the processor to compare the current value to a preset value associated with a stroke distance for the cylinder rod in the pressure containing tube to determine a position of the piston in the pressure containing tube. 
     The method can include using additional computer instructions in the main controller data storage to instruct the processor to use harmonics with the beam to correct the reflected signal based on characteristics of the piston, forming a corrected reflected signal. For example, the method can include using harmonics with the reflected signal to accommodate for surface characteristics of the piston, forming the corrected beam. 
     The method can include using computer instructions in the data storage of the main controller to change a frequency or a pulse width of the beam using on the corrected reflected signal. 
     The method can be used to determine cylinder rod positions for cylinder rods at velocities up to 10 meters per second. 
     In embodiments, the main controller can be in communication with a plurality of client devices through a network, such as the Internet™, a satellite network, a cellular network, or combinations thereof, thereby providing for simultaneous remote monitoring of the cylinder. 
     One or more embodiments can include two lasers on a single pressure containing tube to further ensure safety of the offshore drilling platform if one of the lasers fails during operation. 
     In operation, the first fluid can flow through the first fluid port and into the pressure containing tube. The first fluid within the pressure containing tube can exert a pressure upon the piston, thereby moving the piston in a first direction towards the portion of the pressure containing tube containing the second fluid and the laser proximity detector. The movement of the piston can cause a corresponding movement of the cylinder rod in the first direction. The movement of the cylinder rod can cause a corresponding movement and/or tensioning of equipment that is connected to the cylinder rod, such as at the shackle pin of the cylinder rod. When the pressure of the second fluid within the pressure containing tube is greater than the pressure of the first fluid within the pressure containing tube, the piston can move in a second direction, wherein the second direction can be opposite the first direction. During operation and movement of the piston, the cylinder rod, and any equipment connected thereto, the laser can continually, continuously, or periodically transmit a beam to the piston, cylinder rod, or another portion of the assembly to determine the position of the piston, cylinder rod, or equipment connected thereto. 
       FIG. 1  is a perspective view of a pressure containing tube  10  for tensioning a structure. The pressure containing tube  10  can have a first tube end  11  and a second tube end  12 . 
     A cylinder rod  13  can extend from the second tube end  12 . A cylinder rod second end  19  can connect to a first blind end cap and mount  4 . The first blind end cap and mount  4  can engage a shackle  70  secured to the cylinder rod second end  19  with a shackle pin  72 . 
     The first tube end  11  can engage a second blind end cap and mount  7 . 
     A first fluid  26  from a first fluid source  14  can flow into the pressure containing tube  10  through a first fluid port  23 . 
       FIG. 2  is a cross sectional view of the pressure containing tube  10 . 
     The cylinder rod  13  can have a cylinder rod first end  17  that can engage a piston  25 . The cylinder rod first end  17  can support the piston  25 . 
     A second fluid  27  can be separated from the first fluid  26  by the piston  25  and the cylinder rod  13 . 
     The pressure containing tube  10  can have a cylinder head  22  and a cylinder head seal  24  for providing a leak-free engagement with the cylinder rod  13  during operation with a hydraulic fluid or a pneumatic gas. 
     The second blind end cap and mount  7  can have a hole  46  that can engage a shackle pin. 
     A laser  30  can connect to the second blind end cap and mount  7  and to a wall of the pressure containing tube  10 . The laser  30  can have a camera  37  inside a laser housing  29  that can have an interface plug  31 , allowing the laser to communicate to a main controller. A laser controller  32  can be disposed within the laser housing  29 . 
     A beam  5  from the laser  30  can cause a reflection  6  at the piston  25 . The beam  5  can pass from the laser  30 , through a first optic guide  50 , to a first re-directional surface  52 , through a second optic guide  54 , to a second re-directional surface  56 , through a lens  58 , and out into the second fluid  27 . The lens  58  can be surrounded by a vapor diverter  67 . The optic guides can be housed in the mount portion of the second blind end cap and mount  7 . 
       FIG. 3A  shows a detail of the laser controller  32 . The laser controller  32  can have a laser controller processor  28  and a laser controller data storage  21  with computer instructions  60   b  to form the reflection signal from the detected reflection. 
       FIG. 3B  shows a detail of the camera  37 . The camera  37  can have a camera processor  35  and a camera data storage  34  in communication with the camera processor  35 . The camera data storage  34  can have computer instructions  60   a  to form the reflection signal from the detected reflection. 
       FIG. 4  shows a detail of the main controller  36  connected to the laser through the interface plug  31 . 
     The main controller  36  can have a power supply  38  for operating a main controller processor  43 , a circuit board  41 , and a user interface display  39 . 
     The main controller processor  43  can be in communication with a plurality of client devices  75   a  and  75   b  through a network  73 , allowing for continuous, 24 hours a day, updated communication to remote locations concerning the status of each cylinder and stroke. 
     The main controller  36  can have a main controller data storage  45  with computer instructions stored therein. The main controller  36  can receive a reflection signal  63  from the camera, the laser, or combinations thereof through the interface plug  31 . 
     The main controller data storage  45  can have computer instructions for identifying cylinder rod data  44 , computer instructions for comparing a reflection signal from the camera to a preset value associated with a stroke distance for the cylinder rod  49 , and computer instructions for comparing the reflection signal to a preset velocity  53 . 
       FIG. 5  is a cross sectional view of an optic guide. 
     A lens  58  with a lens retainer  61  can be secured to the optics guide housing  55 . The second re-directional surface  56  can be protected by a second external re-directional surface mounting cap  81 . The second external re-directional surface mounting cap  81  can be placed over the second re-directional surface mount  83  and the second optic guide  54 . 
     The optic guide can include a pressure isolation flange  62 . 
       FIG. 6  is a perspective view of a blind end cap and mount  7  to which the laser can be secured. The mount portion  9  can have a hole  46  for receiving a shackle pin. The mount portion  9  can secure to the cap portion  8 . 
     Also shown are the laser housing  29  which can have the interface plug  31  that can completely surround the laser and the camera. 
     An external re-directional surface mount  76  can be connected to an external re-directional surface mounting cap  78  and a flange  79 . The flange  79  can be used to attach the laser housing  29  to the pressure containing tube. 
       FIG. 7  depicts a flow chart of an embodiment of a method for determining a position of a rod in a cylinder stroke system. 
     The method can include calibrating a laser to determine a limit position of a fully extended cylinder rod, as illustrated by box  1001 . 
     The method can include calibrating the laser to determine a limit position of a fully retracted cylinder rod, as illustrated by box  1002 . 
     The method can include projecting a beam from the laser through at least one optic guide to a piston, as illustrated by box  1003 . 
     The method can include recording a reflection of the beam from the piston and forming a reflection signal, as illustrated by box  1004 . 
     The method can include transmitting the reflection signal to a main controller, as illustrated by box  1005 . 
     The method can include comparing the reflection signal to a preset value associated with a stroke distance for the cylinder rod to determine a cylinder rod position, as illustrated by box  1006 . 
     The method can include using harmonics with the reflected signal to accommodate a surface characteristic of the piston to form a corrected beam, as illustrated by box  1007 . 
       FIG. 8  is a perspective view of a tensioner assembly that can include: one or more sets of cylinder stroke systems including  15   a  and  15   b , a first fluid source  14   a , a second fluid source  14   b , a first fluid source regulator  82   a , a second fluid source regulator  82   b , a first fluid source controller  84  in communication with the first fluid source regulator  82   a , a first gas source  92   a , a second gas source  92   b , a first gas source regulator  98   a , and a second gas source regulator  98   b.    
     The sets of cylinder stroke systems  15   a  and  15   b  can be connected to a structure such as hangers  2   a  and  2   b . The structure can be connected to a floating vessel or a stationary vessel. 
     The first gas source  92   a  can include one or more gas cylinders including  94   a ,  94   b , and  94   c . The gas cylinders  94   a ,  94   b , and  94   c  can be in fluid communication with the first gas source regulator  98   a . For example, a gas conduit  96   a  or tube can provide gas from the first gas source  92   a  to the first gas regulator  98   a . The first gas regulator  98   a  can control the flow of gas to the first fluid source  14   a , such as through gas conduit  96   b . The first gas regulator  98   a  can be disposed on a control skid  102 . 
     The first fluid source  14   a  can include one or more accumulators including  80   a ,  80   c , and  80   f . The accumulators  80   a ,  80   c , and  80   f  can be connected in series and in fluid communication with the first fluid source regulator  82   a.    
     The first fluid source controller  84  can actuate or regulate the first fluid source regulator  82   a . The first fluid source controller  84  can control or regulate the flow of the first fluid from the first fluid source  14   a  to the cylinder stroke system  15   a , such as through gas conduits  96   c  and  96   d . The first fluid source regulator  82   a  can be disposed on a riser recoil skid  110 . 
     The sets of cylinder stroke systems  15   a  and  15   b  can be connected to one or more risers. The risers can be connected to a well. For example, the risers can be connected to the wellhead of the well. 
     The cylinder stroke systems  15   a  and  15   b  are shown having pressure containing tubes  10   a ,  10   c ,  10   d , and  10   f.    
       FIG. 9  depicts a detail of the first fluid source controller  84 . The first fluid source controller  84  can include a fluid flow controller processor  86 , a fluid flow controller data storage  88 , and computer instructions  90  stored in the fluid flow controller data storage  88  for regulating the flow of the first fluid to and from the accumulators based on preset stoke limits of all of the cylinder rods. 
     While these embodiments have been described with emphasis on the embodiments, it should be understood that within the scope of the appended claims, the embodiments might be practiced other than as specifically described herein.

Summary:
A tensioner assembly with a hydraulic fluid and gas is described herein. The tensioner assembly can accurately and reliably detect the position of a cylinder rod in each cylinder of the assembly by using a laser. The data obtained from the laser can be reliable and dependable regardless of any powders, oil, particulate, or scratched lenses of the camera.