Abstract:
Automated make-up and break-up methods and apparatus for rotary oil well drilling are presented. The apparatus includes a drilling database storing tubular type records, a torque wrench having a spinner, and a controller. During make-up, the controller retrieves one or more tubular type records stored in the drilling database in order to configure the torque wrench and/or the spinner to connect an additional tubular section to a tubular string or to disconnect a connection between tubulars in accordance with tubular type parameters. Sensors are employed on various drill rig components and reported sensor values are monitored. Timers are started concurrent with the initiation of various make-up and break-out steps. Exceptions are thrown when sensor values are out-of-range or when steps take too long to complete. Advantages are derived from speeding-up drill rig operations.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a divisional application of U.S. application Ser. No. 12/392,710, filed Feb. 25, 2009, which is continuation application of Application No. PCT/CA2006/001406, filed Aug. 25, 2006, the contents of both of which are hereby incorporated herein in their entirety by express reference thereto. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to oil and gas operations, and in particular to automating oil and gas tubular handling operations. 
       BACKGROUND OF THE INVENTION 
       [0003]    In oilfield operations, tubular strings are made-up and broken-out using an arrangement of mechanized tongs known as a torque wrench. A pair of tongs is used to torque tubular connections for example to thread tubulars together in making-up a tubular string, and to unthread tubulars in breaking-out the string. Tubular strings include, for example, drill strings and liner strings, such as of casing. 
         [0004]    The strata in which well bores are drilled are varied, which requires employing a variety of tubular types. A variety of tubular types must also be used according to well bore depth and drilling techniques. Tubulars include, for example: drill pipe, drill collars, casing, casing collars, well bore liners, cross-over subs, etc. 
         [0005]    Tubular types have varied physical parameters including but not limited to: internal diameter, outside diameter, length, material hardness, thread length, thread pitch, thread hardness, thread taper angle, and are connected according to handling parameters such as set torque, spin speeds, torque wrench actuation speeds, etc. 
         [0006]    Handling tubular strings during well bore drilling and completion is repetitive, and inherently dangerous. Errors and inefficiencies in making-up and breaking-out tubular strings can all lead to inefficient use of resources, downtime, and may jeopardize worker safety. 
         [0007]    There is a need in oil and gas operations to mitigate the above-mentioned issues. 
       SUMMARY OF THE INVENTION 
       [0008]    The invention encompasses a torque wrench configured to manipulate tubulars, the torque wrench including: a plurality of tubular type records retrievably stored in a memory store, each tubular type record being configured to store tubular type specific parameters; and a controller configured to: look-up at least one tubular type record corresponding to a pair of tubulars to retrieve tubular type specific parameters; configure the torque wrench to operate in accordance with the tubular type specific parameters retrieved; and cause the torque wrench to torque a connection between the pair of tubulars. 
         [0009]    In accordance with another aspect of the present invention, there is provided a torque wrench configured to manipulate tubulars, the torque wrench including: a memory store including a plurality records, each record being configured to store a plurality of parameters; a sensor associated with the torque wrench, the sensor reporting a sensor value; a comparator configured to compare values; a controller configured to: look-up at least one record to retrieve at least one parameter; and cause the comparator to compare the reported sensor value against at least one of the retrieved parameters. 
         [0010]    In accordance with yet another aspect of the present invention, there is provided a method of torquing a connection between a pair of tubulars of a tubular string using an oilfield torque wrench having a pair of tongs, the method including: retrieving, from a memory store associated with the torque wrench, tubular type specific parameters specified in at least one tubular type record, configuring the torque wrench to operate in accordance with the tubular type specific parameters retrieved, engaging the pair of tubulars in respective tongs of the torque wrench, and torquing the connection in accordance with the tubular type specific parameters retrieved. In one embodiment, the method further includes the making-up of the tubular string by selecting a tubular type of a tubular to be added to the tubular string. In one embodiment, the method further includes the prior steps of presenting a driller with a selection of tubular types and prompting the driller to select the tubular type of the additional tubular. In another embodiment, the method further includes: a) setting a timer to a time value corresponding to a process step, the time value being specified in the retrieved tubular type parameters; b) starting the timer substantially concurrently with the initiation of the process step; and c) determining whether the process step completes within a time period corresponding to the time value set. In a preferred embodiment, if the process step fails to complete within the time period, the method further includes: counting the failure to complete and reinitiating the process step and resetting the timer. In another embodiment, the reinitiating of the process step and timer further includes automatically reinitiating the process step, and resetting and restarting the timer. In a preferred embodiment, the method further includes monitoring at least one sensor associated with the torque wrench to obtain a sensor value. In yet a further preferred embodiment, the method further includes at least one of the following: logging the sensor value; displaying the sensor value on a driller&#39;s interface; comparing the sensor value against at least one of the tubular specific parameters; or a combination of the above. In another preferred embodiment, the method further includes at least one of: a) logging an indication that the reported sensor value is within a sensor value range; b) logging an indication that the reported sensor value is outside the sensor value range; c) displaying a sensor value out-of-sensor-value-range-indication on the driller&#39;s interface; d) alerting an off-site entity of the sensor value out-of-sensor-value-range indication; e) raising an alarm; f) repeating a process step once; g) repeating the process step for a predetermined number of times and increasing a counter each time; h) repeating the process step with the torque wrench configured to operate in accordance with a modified parameter; i) skipping the process step; j) restarting; k) prompting for human-intervention; and l) shutting-down. 
         [0011]    It is to be understood that other aspects of the present invention will become readily apparent to those of ordinary skill in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable for other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0012]    Referring to the drawings wherein like reference numerals indicate similar parts throughout the several views, several aspects of the present invention are illustrated by way of example, and not by way of limitation, in detail in the figures, wherein: 
           [0013]      FIG. 1  is a schematic diagram showing, in accordance with one embodiment of the invention, elements implementing tubular handling automation; 
           [0014]      FIG. 2  is a flow diagram showing process steps implementing tubular handling automation; and 
           [0015]      FIG. 3  is a flow diagram showing process steps implementing process step monitoring. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    The detailed description set forth below in connection with the appended drawings is intended as a description of various preferred embodiments of the present invention and is not intended to represent the only embodiments contemplated by the inventor. The detailed description includes specific details for the purpose of providing a comprehensive understanding of the present invention. It will be apparent to those of ordinary skill in the art, however, that the present invention may be practiced without these specific details. 
         [0017]    In accordance with one embodiment of the invention, an oilfield apparatus  100  for tubular handling operations is shown in  FIG. 1 . The apparatus may include a torque wrench  130 , a drilling database  110 , and a control module  140 . During tubular handling, the torque wrench  130  may be used to torque connections between tubulars  160 , for example to make up the connections or break them out. The torque wrench  130  may be used to torque a connection including making-up a connection between tubulars (threadingly engaging tubulars together) or breaking-out a connection between tubulars. The torque wrench  130  may include an upper tong  132  used to engage a tubular  160  to be added to a tubular string  162  during make-up or the last tubular  160  in the tubular string  162  during break-out; a lower tong  134  used to engage the stump of the tubular string  162 ; and a spinner. 
       Pipe Profiling  
       [0018]    A multitude of different tubular types are employed to drill and complete well bores  102 . Different tubulars  160  are required to drill though different strata  104  and to achieve desired tubular string characteristics. 
         [0019]    The drilling database  110  may include a multitude of tubular type records  112 . Each tubular type record  112  corresponds to a tubular type specification and for a particular tubular type may include a user-friendly name stored in a human readable string of characters describing the corresponding tubular type. For example: “4 in drill pipe”, “6 in collar”, “4½ in to 6 in sub,” etc. As will be described herein below, the user-friendly tubular name may be displayed, for example on various screens of a human-machine “driller&#39;s” interface, allowing the driller to select or specify the use of the corresponding tubular type record by interacting with various items (selectors, touch screen areas, buttons, list elements, etc.) associated with the displayed user-friendly name. Any human-machine interface may be used, such as for example a computerized, analog, stationary, mobile, remote, drill site-located, etc. driller&#39;s interface. 
         [0020]    Each tubular type record  112  may further store tubular type specific parameters such as, but not limited to: inner diameter, outer diameter, tubular length from sealing face to sealing face, maximum torque specification, a percentage of full torque cylinder make-up speed, a percentage of full torque cylinder break-out speed, connection spin-in time, connection spin-out time, etc. 
         [0021]    The maximum torque specification specifies the maximum amount of torque to be used with the corresponding tubular. The connection spin-in time value specifies the amount of time that the spinner will run to take the tubular  160  from being uncoupled to the point when make-up torque is to be used. The connection spin-out time value specifies the amount of time that the spinner is driven to take the tubular  160  from the break-out torque point to the tubular  160  being uncoupled. The percentage of full torque cylinder make-up speed value specifies the torque cylinder make-up speed fraction of full speed is to be used during make-up. The percentage of full torque cylinder break-out speed value specifies the torque cylinder break-out speed fraction of full speed is to be used during break-out. The percentage of torque cylinder speed value may be employed to set a hydraulic valve to a percentage of being fully open, to control the speed with which the piston of a hydraulic cylinder moves in swiveling the tongs of the torque wrench  130  relative to each other. Faster speeds may be employed for smaller diameter tubulars  160  or when accuracy is of a lesser importance. Slower speeds may be employed for larger diameter tubulars  160  or when greater accuracy is desired. 
         [0022]    In accordance with one implementation of the first embodiment of the invention, the database  110  may include a plurality of different tubular type records  112 , each record relating to a tubular type and its specification. Employing the drilling database  110 , spares the driller from repeatedly entering tubular type specific parameters to operate the torque wrench  130  at a substantial reduction of operational overheads. The tubular type specific parameters for the plurality of tubulars used for a drilling operation are entered using a tubular type specific parameter entry screen or interface presented to an operator, such as but not limited to via the driller&#39;s interface. The operator selects each tubular type record  112  in the database, one at the time, and enters a parameter value for each parameter value field in the record using a keyboard. In order to prevent unwanted tampering with the drilling database  110  and perhaps with the drilling operation, the drilling database  110  may be password protected. 
         [0023]    The driller is subsequently enabled to select a tubular type record  112  from the group of tubular type records in the database for example as shown on a tubular type record selection screen of the driller&#39;s interface, as needed, during an operation. 
         [0024]    In one embodiment, the driller may select a tubular type record  112  and modify the tubular type record  112  before it is used to operate the torque wrench in order to change a tubular type specific parameter, such as, but not limited to, the maximum torque specification parameter. 
         [0025]    After a particular tubular type record  112  is selected by the driller, the tubular type specific parameters are employed to configure and operate the torque wrench for example by setting up and/or controlling operation of control valves, motors and drive systems, timers, counters, notifications, etc. of the torque wrench  130 . The controller  140  may retrieve or obtain the tubular type specific parameter values for the currently selected or active tubular type record  112 , and writes the values in corresponding registers at corresponding working memory locations where torque wrench logic expects the parameters to be specified. The torque wrench logic employs the values to set pressure valves, timers, counters, etc. 
         [0026]    The tubular type record  112  to be used for torquing any connection may be expressly selected by the driller, or be selected by default. 
         [0027]    In drilling a well bore, the bit wears out and requires bit replacement or core samples need to be taken of the formation being drilled through, as a result, the tubular string  162  may be made-up and broken-out a number of times before the well bore is drilled to the desired depth. 
         [0028]    In accordance with the embodiment of the invention, the control module  140  is employed to automate aspects of tubular string make-up and break-out. Without limiting the invention, the control module  140  may include one or more of: hardware, hardware logic, firmware, microprocessor(s), memory storage, software, ancillary electronics, instrumentation, etc. 
         [0029]    Without limiting the invention, during make-up, the control module  140  may be configured to: look-up ( 202 ) the tubular string specification  114  in the drilling database  110 ; present to the operator a default tubular type of the next tubular to be added to the tubular string; provide the operator with the opportunity to change the tubular type if necessary; look-up ( 206 ) the tubular type record  112  in the drilling database  110  to retrieve tubular type specific parameters; prompt ( 208 ) for the retrieval of an additional tubular  160 ; pre-con figure 110  the torque wrench  130  to operate in accordance with tubular type specific parameters retrieved; subsequent to the retrieval ( 208 ) of, and stabbing into the stump, the additional tubular  160 , instruct ( 210 ) the torque wrench  130  to engage the stump of the tubular string  162  and the retrieved tubular  160 ; and to appropriately instruct ( 210 ) the torque wrench  130  to connect the retrieved tubular  160  to the tubular string  162  in accordance with the retrieved tubular type specific parameters. The retrieved tubular  160  is connected to the existing tubular string  162  (stump) by threadingly engaging a pin end of the retrieved tubular  160  to a box end of the last tubular  160  of the tubular string  162 . 
         [0030]    In accordance with the first embodiment of the invention, a make-up process  200  directed by the control module  140  is shown in  FIG. 2 . Without limiting the invention, the method of making-up a tubular string  162  for well bore drilling may include a multitude of steps. 
         [0031]    As tubulars  160  are to be connected to each other, for each connection, the last tubular  160  connected to the tubular string  162  may be used as the default tubular  160  for further connections. Once the tubular type is selected, the tubular type will be used until the driller selects a new tubular type. The driller may be given an opportunity  202  to select a different tubular type. 
         [0032]    Considering  204  that the tubulars  160  of each pair may be of the same type or of different types, for each connection therefore, at least one tubular type record  112  may be looked-up  206  by the controller  140  in the drilling database  110  to obtain tubular type specific parameters. If the last tubular  160  in the tubular string  162  and the tubular  160  to be added are of the same type, then only one tubular type record  112  may be looked-up  206 . If the tubular  160  to be added is different then the last tubular  160  of the tubular string  162 , then both corresponding tubular type records  112  may be looked-up  206 . 
         [0033]    During a method to make up a connection in a tubular string, a physical tubular  160  to be added to the tubular string  162  is retrieved  208  and stabbed into the stump. The controller  140  may prompt the driller to confirm that a tubular  160  has been stabbed into the stump. Alternatively, the stabbing of a tubular  160  into the stump may be sensed. The controller  140  instructs  210  the torque wrench  130 , to engage the tubular string  162  stump and the retrieved tubular  160  to be connected thereto. The retrieved tubular  160  is connected  212  to the tubular string  162  in accordance with retrieved tubular type specific parameters specified in the at least one tubular type record. 
         [0034]    Without limiting the invention, connecting  212  the retrieved tubular  160  to the tubular string  162  may be divided into three steps: spin-in  220 , shoulder-up  222 , and tighten  224 . The spin-in step  220  is performed by the spinner by rapidly spinning the tapered pin end of the retrieved tubular  160  into the box end of the tubular string stump  162 , which is the box end of the last tubular  160  in the tubular string  162 . The spinner may be preset to spin the tubular in for the duration of the spin-in time specification obtained from the tubular type record  112 . Shouldering-up  222  is achieved when the entire length of the pin end thread of the retrieved tubular  160  has been threaded in. If shouldering-up is not achieved after the expiration of the spin-in time, the spinner may be spun again perhaps for a shorter spin-in time. In operating the torque wrench tongs to make-up the connection, tightening  224  requires applying the torque specified in the at least one tubular type record  112  at the percentage of torque cylinder make-up speed also specified in the tubular type record  112 . For example, when dissimilar tubulars  160  are connected, the torque used may be the lower of the two. 
         [0035]    The torque wrench  130  may operate without human intervention to complete tasks. In so doing, the controller  140  may look-up tubular type specific parameters, set up the torque wrench  130  to accommodate the next tubular  160  based on the parameters, and operate the torque wrench to make-up the connection according to those parameters. 
         [0036]    The control module  140  may include feedback logic  144 , monitoring logic  146 , and may interface with monitoring components. 
         [0037]    Considering that oil well drilling operations are costly, if a tubular string  162  is damaged, substantial costs and downtime can be incurred. Monitoring the operational parameters of the torque wrench  130  provides a measure of safety against mishaps. 
         [0038]    Without limiting the invention, the monitoring components may include sensors  170  affixed to various drill rig components such as, but not limited to: a switch, a timer, a counter, a temperature probe, a strain gage, a load cell, a tension cell, a pressure load cell, a transducer, a deflection transducer, a linear transducer, a pressure transducer, etc. Sensors  170  report, for example, sensor values, component function, or geometry, and switch positions via feedback logic  144  to the monitoring logic  146  of the control module  140 . For example, reported sensor values, may include: oil temperature, hydraulic fluid pressure, a degree of piston extension, etc. 
         [0039]    For example, a torque sensor  170  may be affixed to the torque wrench  130  to report  242  torque sensor values as tubulars  160  are connected to the drill string  162 . A drilling operator can be provided with a log of torque values. The drilling contractor can audit the operation of the torque wrench  130  based on the log. 
         [0040]    For example, without limiting the invention, the torque sensor  170  may include at least one pressure transducer measuring the hydraulic pressure used by a hydraulic piston used to displace the upper tong  132  against the lower tong  134 . 
         [0041]    During subsequent tubular string break-out, the control module  140  may look-up at least one tubular type record  112  to obtain operational parameters with which to configure the torque wrench  130 , such as, but not limited to, the torque to apply with the torque wrench  130  in breaking-out a connection. At least initially, the torque wrench  130  may employ the percentage of the typical torque cylinder break-out speed value stored in the tubular type record  112  of the tubular  160  to be disconnected as the maximum speed to be applied, as during normal use of the tubular string to drill the well bore the connections relax due to vibration. If the initial torque cylinder break-out speed applied is not enough to break-out the connection, it may be surmised that the connection was not torqued property as stress forces imparted to the tubular string  162  during the drilling operation have applied additional torque to the connection. If breakout is not achieved, the torque wrench  130  is reconfigured to attempt break-out again at a higher torque/torque cylinder break-out speed percentage. 
         [0042]    In accordance with the another embodiment of the invention, the control module  140  is adapted to issue start/stop instructions to various controlled components including, but not limited to: the spinner, the drive system between the lower tong  134  and the upper tong  132 , a drive system for tubular gripping dies, etc. 
         [0043]    The control module  140  may issue instructions subject and/or responsive to a time delay since a previous start instruction and/or subject to feedback. 
       Onboard Diagnostics and Fault Response 
       [0044]    The monitoring logic  142  is not limited to monitoring torque measurements, a myriad of feedback components may be employed to quantify a variety of measurables and to detect a variety of events. The monitoring and logging of feedback information allows for diagnostics to be performed. 
         [0045]    In accordance with an exemplary implementation of the exemplary embodiment of the invention, the monitoring logic  146  monitors a multitude of measurables and/or events, combinations of parameters such as, but not limited to: time duration, switch position, reported sensor value, etc. Controller  140  may employ a comparator  154  to compare reported sensor values to: a desired sensor value, a sensor value threshold, an acceptable sensor value range, a counter, a time value, etc. Should a reported sensor value be out-of-range, an exception can be thrown. A comparison indicator associated with the driller&#39;s interface may report the exception to the driller. 
         [0046]    In accordance with an exemplary implementation of the exemplary embodiment of the invention, the controller  140  employs a meta process  300  shown in  FIG. 3  wherein various steps to be performed in the process  200  may have an associated time interval during which the process step is expected to complete. Without limiting the invention, timer values may be specified in, and obtained  302  from the tubular type records  112 . A corresponding timer  156  may be set and started  304  at substantially the same time the process step is initiated  306  by the controller  140 . 
         [0047]    Each process step may have a process step completion confirmatory event, which may be detected by a sensor; the desired result being that each process step would be completed  308  before the corresponding timer  156  reaches an expected end time  310 . 
         [0048]    The step completion confirmatory event may as simple as a reported sensor value reaching a sensor value threshold specified in a tubular type record  112 . For example, a linear transducer may be employed to confirm that a tong being moved to engage a tubular  160  has reached a start position. 
         [0049]    The step completion confirmatory event may be complex, such as for example, wherein a combination of multiple reported sensor values are compared against corresponding sensor value ranges specified in at least one tubular type record  112 , the substantial statistical correlation of which being considered to confirm the completion of the process step. Accordingly, previous human-monitored step completion confirmatory events such as, but not limited to: shouldering-up a tubular  160 , breaking-out a connection, etc. are mapped to complex step completion confirmatory events wherein the results of comparisons of output values of multiple sensors for example measuring torque, hydraulic pressure, elapsed time, etc. are combined. 
         [0050]    If a step fails to complete, the step may be repeated automatically or other actions may be taken without human intervention as detailed herein below. If the step fails to complete repeatedly, the number of times the step has failed to complete may be monitored via corresponding counters  142 . 
         [0051]    In accordance with an embodiment of the invention, the elapse  310  of the timer  156  before the step completion confirmatory event comes about  308 , may trigger an exception  312 . Typical exceptions may be: 
         [0052]    merely reported for statistical purposes; 
         [0053]    reported for trending analysis; 
         [0054]    raising alerts; 
         [0055]    raising alarms; and 
         [0056]    wired/configured to shutdown the torque wrench  130  and/or the drilling rig. 
         [0057]    The exceptions may be reported to the driller&#39;s interface, or may be reported off site via a transceiver. 
         [0058]    An increase in reliability may be achieved because automated monitoring allows for error detection before damage occurs, statistical analysis of trends in operation, and reduces the possibility for erroneous human interpretation of data. 
         [0059]    In accordance with the embodiment of the invention, once an exception is thrown, the controller  140  may, without human intervention, depending on the process step which resulted in the thrown exception, intervene to address the exception. This can include one or more of the following: 
         [0060]    repeat the step once; 
         [0061]    repeat the step for a predetermined number of times and incrementing a counter each time; 
         [0062]    repeat the step with different torque wrench parameter settings, such as for example higher torque; —skip the step; 
         [0063]    restart; 
         [0064]    shutdown a drilling ring subsystem; and 
         [0065]    prompt for human intervention. 
         [0066]    The use of sensors, timers  156 , switches, and comparator  154  allows use of measured, and reported, events and sensor values, devoid of human opinion/interpretation/oversight, to audit the operation of the torque wrench  130 , and address and direct resolution of a deviation from expected torque wrench operation. 
         [0067]    For certainty, the monitoring performed by the controller  140  described herein also applies to general torque wrench  130  operations distinct from torquing connections, torque wrench operational parameters being stored in records in a working store separate from the tubular type records. The torque wrench working store may include the drilling database  110 . 
       Remote Monitoring and Troubleshooting  
       [0068]    The reduction in the number of personnel operating the drilling rig provided leads to a reduction in the number of skilled individuals that can assess the status of the drilling operation from the benign alert to the undesirable destruction of the drilling rig. 
         [0069]    In accordance with an implementation of the embodiment of the invention, the drill master may be provided with a wireless interface, typically embodying a portable wireless device incorporating controls otherwise integrated into the drill master&#39;s interface in the cabin. The portable wireless device may be worn around the drill master&#39;s neck, over the shoulder, around the waist, etc. 
         [0070]    Drilling investments being large, mitigating the reduction in personnel includes a monitoring and troubleshooting interface whereby off-site personnel is provided with a remote monitoring and troubleshooting interface. Off-site personnel (service department) can login remotely and may, without limiting the invention, either: 
         [0071]    observe tracked operational parameters of the entire drilling operation in real time as sensor values are being reported; 
         [0072]    view the values of the operational parameters at the time the rig/torque wrench  130  were shutdown; 
         [0073]    audit operational historical parameter value trends; 
         [0074]    audit operational parameter value trends leading to an event; 
         [0075]    perform statistical analysis on parameter values and parameter value trends; and 
         [0076]    diagnose drilling operations. 
         [0077]    In accordance with an implementation of the embodiment of the invention, as drill rigs are typically operated in geographically remote locations, a telecommunications infrastructure is employed. Without limiting the invention thereto, the telecommunications infrastructure may include: satellite communications, wireless communications, and wired communications. In one embodiment, the infrastructure may include the Internet. 
         [0078]    Although various aspects of the present invention have been described herein including for example a drilling database, a tubular type record, tubular type specific parameters, a driller&#39;s interface, a controller, a sensor, a comparator, a comparison indicator, a interface, wireless interface, a virtual interface, and a transceiver, it is to be understood that each of these features may be used independently or in various combinations, as desired, in a torque wrench. 
         [0079]    The previous description of the disclosed embodiments is provided to enable any person of ordinary skill in the art to make or use the present invention. Various modifications to those embodiments will be readily apparent to those of ordinary skill in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article “a” or “an” is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 USC §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or “step for.”