Patent Publication Number: US-2022214315-A1

Title: Probe, system, and method for non-destructive ultrasonic inspection

Description:
FIELD 
     This disclosure relates generally to non-destructive inspection, and more particularly to non-destructive ultrasonic inspection of differently sized parts using the same probe. 
     BACKGROUND 
     Various parts, such as parts for aircraft, are non-destructively inspected prior, during, or after use. Some parts are made from laminated composite materials, which may inadvertently include abnormalities, such as cracks and voids. Accordingly, parts made from laminated composite materials are often non-destructively inspected to assess the quality of the parts and the presence of abnormalities. 
     According to one known method of non-destructive inspection, ultrasonic energy from an inspection probe is used to generate a representation or image of the interior of a part. The representation or image is used to identify abnormalities in the part. Some parts have unique sizes or shapes that require an inspection probe specifically designed to inspect the unique size or shape of a part. While appropriate for inspecting parts having a given size and shape, such specifically-designed probes are not conducive to inspecting parts having a different size or shape. Accordingly, in order to inspect parts having different sizes or shapes, many conventional techniques require multiple specifically-designed probes. In addition to the added cost of using multiple probes, the process of switching between multiple probes can be difficult and time consuming. 
     Some conventional probes are designed to inspect multiple parts having different sizes or shapes. However, such probes do not provide adequate fluid coupling between the probe and the part for accurate ultrasonic inspection. 
     SUMMARY 
     The subject matter of the present application provides examples of non-destructive inspection devices, systems, and methods that overcome the above-discussed shortcomings of prior art techniques. 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 current non-destructive inspection devices. 
     Disclosed herein is a probe for non-destructively inspecting a hat stiffener. The probe comprises a body, which comprises an inspection surface and a slot formed in the inspection surface. The probe also comprises an ultrasonic-sensor assembly that is fixed to the body and open to the inspection surface via the slot. The probe further comprises a surface-engagement assembly that comprises a first foot and a second foot. The surface-engagement assembly is movably coupled to the body such that the first foot and the second foot are on opposite ends of the slot of the body and the first foot and the second foot are movable relative to the body and the ultrasonic-sensor assembly. The preceding subject matter of this paragraph characterizes example 1 of the present disclosure. 
     The first foot is movable between a first retracted position and a first extended position. The first foot is further from the inspection surface in the first extended position than in the first retracted position. The second foot is movable between a second retracted position and a second extended position. The second foot is further from the inspection surface in the second extended position than in the second retracted position. 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 probe further comprises a first biasing mechanism that is coupled to the body and the surface-engagement assembly and configured to bias the first foot into the first extended position. The probe also comprises a second biasing mechanism that is coupled to the body and the surface-engagement assembly and is configured to bias the second foot into the second extended position. The preceding subject matter of this paragraph characterizes example 3 of the present disclosure, wherein example 3 also includes the subject matter according to example 2, above. 
     The first foot and the second foot are co-movable relative to each other. The preceding subject matter of this paragraph characterizes example 4 of the present disclosure, wherein example 4 also includes the subject matter according to any one of examples 2-3, above. 
     The surface-engagement assembly further comprises a crossbar that is movable relative to the body and the ultrasonic-sensor assembly and that intercouples the first foot and the second foot such that translational movement of the crossbar in a first direction away from the inspection surface corresponds with movement of the first foot toward the first retracted position and movement of the second foot toward the second retracted position and translational movement of the crossbar in a second direction toward the inspection surface and opposite the first direction corresponds with movement of the first foot toward the first extended position and movement of the second foot toward the second extended position. The preceding subject matter of this paragraph characterizes example 5 of the present disclosure, wherein example 5 also includes the subject matter according to example 4, above. 
     The body further comprises a guiderail. The crossbar comprises a guiderail slot slidably engaged with the guiderail such that the guiderail limits movement of the crossbar to the first direction and the second direction. The preceding subject matter of this paragraph characterizes example 6 of the present disclosure, wherein example 6 also includes the subject matter according to example 5, above. 
     The first foot and the second foot are slidable relative to the body along linear paths. The preceding subject matter of this paragraph characterizes example 7 of the present disclosure, wherein example 7 also includes the subject matter according to any one of examples 1-6, above. 
     The first foot is movable along a first path relative to the body. The second foot is movable along a second path relative to the body. An angle defined between the first path and the second path is perpendicular or oblique. 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 1-7, above. 
     The first foot comprises a first engagement surface configured to engage the hat stiffener. The first engagement surface is substantially perpendicular to the first path. The second foot comprises a second engagement surface configured to engage the hat stiffener. The second engagement surface is substantially perpendicular to the second path. The preceding subject matter of this paragraph characterizes example 9 of the present disclosure, wherein example 9 also includes the subject matter according to example 8, above. 
     The first foot comprises a first engagement surface configured to engage the hat stiffener. The first foot further comprises a first groove formed in the first engagement surface. The second foot comprises a second engagement surface configured to engage the hat stiffener. The second foot further comprises a second groove formed in the second engagement surface. The probe further comprises a fluid chamber open to the ultrasonic-sensor assembly and defined at least partially between the inspection surface of the body, the first groove, and the second groove. The fluid chamber is configured to receive a fluid during non-destructive inspection of the hat stiffener. A volume of the fluid chamber changes as the first foot and the second foot move relative to the body and the ultrasonic-sensor assembly. 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. 
     The first foot comprises a first engagement surface configured to engage the hat stiffener. The first foot further comprises opposing first beveled leading and trailing edges and the first engagement surface is interposed between the opposing first beveled leading and trailing edges of the first foot. The second foot comprises a second engagement surface configured to engage the hat stiffener. The second foot further comprises opposing second beveled leading and trailing edges and the second engagement surface is interposed between the opposing second beveled leading and trailing edges of the second foot. The preceding subject matter of this paragraph characterizes example 11 of the present disclosure, wherein example 11 also includes the subject matter according to any one of examples 1-10, above. 
     The first foot comprises a first engagement surface configured to engage the hat stiffener. The second foot comprises a second engagement surface configured to engage the hat stiffener. The first engagement surface and the second engagement surface are planar. The preceding subject matter of this paragraph characterizes example 12 of the present disclosure, wherein example 12 also includes the subject matter according to any one of examples 1-11, above. 
     Further disclosed herein is a system for non-destructively inspecting a hat stiffener. The system comprises a robotic arm. The system also comprises a probe that is fixed to the robotic arm. The probe comprises a body, which comprises an inspection surface and a slot formed in the inspection surface. The probe also comprises an ultrasonic-sensor assembly that is fixed to the body and open to the inspection surface via the slot. The probe further comprises a surface-engagement assembly that comprises a first foot and a second foot. The surface-engagement assembly is movably coupled to the body such that the first foot and the second foot are on opposite ends of the slot of the body and the first foot and the second foot are movable relative to the body and the ultrasonic-sensor assembly. The robotic arm is configured to autonomously move the probe along the hat stiffener such that at least a portion of the inspection surface of the body contacts the hat stiffener and the first foot and the second foot contact the hat stiffener. The preceding subject matter of this paragraph characterizes example 13 of the present disclosure. 
     The hat stiffener comprises a cap portion having a first radius. The first foot and the second foot are in first positions relative to the body and the ultrasonic-sensor assembly when in contact with the hat stiffener. The robotic arm is configured to autonomously remove the probe from the hat stiffener and autonomously move the probe along a second hat stiffener, having a second radius that is different than the first radius, such that at least a portion of the inspection surface of the body contacts the second hat stiffener and the first foot and the second foot contact the second hat stiffener. The first foot and the second foot are in second positions relative to the body and the ultrasonic-sensor assembly when in contact with the second hat stiffener. The first positions are different than the second positions. 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 14, above. 
     Additionally disclosed herein is a method of non-destructively inspecting a hat stiffener. The method comprises the step of contacting a cap portion of the hat stiffener with an inspection surface of a body of a probe. The method also includes the step of moving a first foot of the probe, relative to the body, to contact a first web portion of the hat stiffener when the inspection surface is contacting the cap portion of the hat stiffener. The method additionally includes the step of moving a second foot of the probe, relative to the body, to contact a second web portion of the hat stiffener when the inspection surface is contacting the cap portion of the hat stiffener. The method further includes the step of ultrasonically inspecting the cap portion of the hat stiffener with an ultrasonic-sensor assembly, fixed to the body and open to the inspection surface via a slot formed in the inspection surface of the body. The preceding subject matter of this paragraph characterizes example 15 of the present disclosure. 
     The method further comprises the step of filling a fluid chamber of the probe with a fluid, the fluid chamber being open to the ultrasonic-sensor assembly and defined at least partially between the inspection surface of the body, a first groove formed in the first foot, and a second groove formed in the second foot. The method also comprises the step of changing a volume of the fluid chamber by moving the first foot relative to the body and moving the second foot relative to the body. 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. 
     The method further comprises the steps of biasing the first foot away from the inspection surface and toward the second foot and biasing the second foot away from the inspection surface and toward the first foot. 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 15-16, above. 
     The first foot and the second foot are in first positions, relative to the body when in contact with the first web portion and the second web portion, respectively, of the hat stiffener and when the inspection surface of the body is in contact with the cap portion of the hat stiffener. The method further comprises the step of removing the probe from the hat stiffener. The method also comprises the step of contacting a cap portion of a second hat stiffener with the inspection surface of the body of the probe. An amount of the inspection surface in contact with the cap portion of the second hat stiffener is different than the amount of the inspection surface in contact with the cap portion of the first hat stiffener. The method additionally comprises the step of moving the first foot of the probe, relative to the body, into a second position to contact a first web portion of the second hat stiffener when the inspection surface is contacting the cap portion of the second hat stiffener. The method further comprises the step of moving the second foot of the probe, relative to the body, into a second position to contact a second web portion of the second hat stiffener when the inspection surface is contacting the cap portion of the second hat stiffener. The method also comprises the step of ultrasonically inspecting the cap portion of the second hat stiffener with the ultrasonic-sensor assembly. The first positions are different than the second positions. The preceding subject matter of this paragraph characterizes example 18 of the present disclosure, wherein example 18 also includes the subject matter according to any one of examples 15-17, above. 
     The steps of moving the first foot of the probe into the second position and moving the second foot of the probe into the second position comprises co-moving the first foot and the second foot into the second positions. The preceding subject matter of this paragraph characterizes example 19 of the present disclosure, wherein example 19 also includes the subject matter according to example 18, above. 
     The first foot of the probe is moved, relative to the body, along a first path. The second foot of the probe is moved, relative to the body, along a second path. An angle defined between the first path and the second path is perpendicular or oblique. 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 15-19, 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, including embodiments 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, embodiment, or implementation. In other instances, additional features and advantages may be recognized in certain examples, embodiments, and/or implementations that may not be present in all examples, embodiments, 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 probe for non-destructively inspecting a hat stiffener, according to one or more examples of the present disclosure; 
         FIG. 2  is a schematic, perspective view of the probe of  FIG. 1 , according to one or more examples of the present disclosure; 
         FIG. 3  is a schematic, top plan view of the probe of  FIG. 1 , according to one or more examples of the present disclosure; 
         FIG. 4  is a schematic, bottom plan view of the probe of  FIG. 1 , according to one or more examples of the present disclosure; 
         FIG. 5  is a schematic, perspective view of the probe of  FIG. 1 , shown inspecting a hat stiffener, according to one or more examples of the present disclosure; 
         FIG. 6  is a schematic, perspective view of a system for non-destructively inspecting a hat stiffener, according to one or more examples of the present disclosure; 
         FIG. 7  is a schematic, front elevation view of the probe of  FIG. 1 , shown inspecting a hat stiffener having a first radius, according to one or more examples of the present disclosure; 
         FIG. 8  is a schematic, front elevation view of the probe of  FIG. 1 , shown inspecting a hat stiffener having a second radius, according to one or more examples of the present disclosure; and 
         FIG. 9  is a schematic flow diagram of a method of non-destructively inspecting a hat stiffener, 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. 
     Disclosed herein is probe for non-destructively inspecting a hat stiffener. According to some examples, as shown, the hat stiffener is a rounded hat stiffener. The probe includes movable feet that engage the hat stiffener to help contain fluid within a fluid chamber of the probe as the probe inspects the hat stiffener. The feet are configured to movably conform to hat stiffeners of varying shapes and sizes. Accordingly, the same probe can be used to inspect multiple differently-configured hat stiffeners, which saves time and costs over prior art techniques requiring the swapping out of multiple differently-configured probes in order to inspect multiple hat stiffeners of different configurations. Additionally, the feet of the probe of the present disclosure cooperate with each other to facilitate self-centering of the probe on the hat stiffener. 
     Referring to  FIG. 1 , according to some examples, a probe  100  for non-destructively inspecting hat stiffeners is shown. The probe  100  includes a body  102  and an ultrasonic-sensor assembly  104  fixed to the body  102 . In certain examples, the ultrasonic-sensor assembly  104  is non-movably fixed to the body  102 . Accordingly, in such examples, the ultrasonic-sensor assembly  104  does not move relative to the body  102 . As shown in  FIG. 1 , the body  102  can include an interior cavity  103  in which the ultrasonic-sensor assembly  104  is positioned when fixed to the body  102 . Although not specifically shown, the ultrasonic-sensor assembly  104  includes an ultrasonic sensor and a housing that houses the ultrasonic sensor. The ultrasonic sensor is an ultrasonic sensor array, such as an ultrasonic linear phased array. For example, the ultrasonic sensor can include multiple ultrasonic transceivers that are configured to asynchronously generate ultrasonic signals, which combine to form a beam of sound directed into the hat stiffener under inspection. The ultrasonic transceivers are also configured to receive and detect soundwaves from the hat stiffener under inspection. The soundwaves from the hat stiffener are reflected portions of the beam of sound directed into the hat stiffener. Based on the characteristics of the reflected portions of the beam of sound from the hat stiffener, abnormalities in the hat stiffener can be detected. The ultrasonic-sensor assembly  104  includes an electrical coupler  116  with one or more wires for facilitating the transmission of power to the ultrasonic-sensor assembly  104  and data to and from the ultrasonic-sensor assembly  104 . 
     As shown in  FIG. 2 , the body  102  includes an inspection surface  134  and a slot  128  formed in the inspection surface  134 . The inspection surface  134  is configured to contact an outer surface  152  of a hat stiffener  150  (e.g., stringer) while the ultrasonic-sensor assembly  104  directs soundwaves to and receives soundwaves from the hat stiffener  150 . Referring to  FIG. 5 , the cap portion  158  joins together a first web portion  156 A and a second web portion  156 B of the hat stiffener  150 . In other words, the cap portion  158  is between and separates the first web portion  156 A from the second web portion  156 B. The hat stiffener  150  further includes a first flange portion  154 A directly coupled to the first web portion  156 A and a second flange portion  154 B directly coupled to the second web portion  156 B. The first flange portion  154 A and the second flange portion  154 B are configured to interface with another part or component such that the hat stiffener  150  helps to stiffen the part or component. In some examples, except for a radiused section between corresponding web and flange portions, the first web portion  156 A, the second web portion  156 B, the first flange portion  154 A, and the second flange portion  154 B are planar. The cap portion  158  is contoured or curved in elevation view, such that in elevation view the cap portion  158 , the first web portion  156 A, and the second web portion  156 B define a shape having two substantially linear portions connected by an arcuate portion, where the linear portions are angled relative to each other. The curvature of the outer surface  152  of the cap portion  158  has a radius. For example, in  FIG. 7 , the outer surface  152  of the cap portion  158  of the hat stiffener  150  has a radius r 1 . In contrast, in  FIG. 8 , the outer surface  152  of the cap portion  158  of the hat stiffener  150  has a radius r 2 . In the illustrated examples, the radius r 1  is greater than the radius r 2 . 
     In some examples, the inspection surface  134  has a shape that complements the shape of the outer surface  152  of the hat stiffener  150 . Generally, the probe  100  is used to non-destructively inspect a cap portion  158  of the hat stiffener  150 , which in the illustrated examples is a round cap portion. Accordingly, the inspection surface  134  is shaped to complement the shape of the outer surface  152  of the cap portion  158  of the hat stiffener  150  in some examples. As shown in  FIG. 2 , the inspection surface  134  has a contoured shape that generally complements the contoured shape of the cap portion  158  of the hat stiffener  150 . The shape of the inspection surface  134  is fixed. Therefore, more or less of the inspection surface  134  contacts the outer surface  152  of the cap portion  158  during inspection depending on the radius of the cap portion  158 . Accordingly, the amount of the inspection surface  134  that contacts the cap portion  158  during inspection may vary depending on the radius of the cap portion  158 . For instance,  FIGS. 7 and 8  illustrate different amounts of the inspection surface  134  contacting the cap portion  158 . In some examples, the ultrasonic sensor array of the ultrasonic-sensor assembly  104  is also shaped to complement the shape of the outer surface  152  of the cap portion  158  of the hat stiffener  150 . Such a configuration enables the ultrasonic transceivers of the ultrasonic sensor array to generate ultrasonic signals that are substantially perpendicular to the outer surface  152  of the cap portion  158  of the hat stiffener  150  where the ultrasonic signals impact the outer surface  152  of the cap portion  158 . Moreover, for inspecting cap portions  158  of different hat stiffeners  150  that have different radii, perpendicularity of the ultrasonic signals can be achieved using an ultrasonic linear phased array. A ultrasonic linear phased array can phase shift the generation of the ultrasonic signals from each transceiver of the array to change the directionality of the resultant ultrasonic beam to conform to the different radii of the cap portions  158  and maintain perpendicularity of the resultant ultrasonic beam with the cap portions  158 . 
     As shown in  FIG. 2 , the slot  128  formed in the inspection surface  134  extends from the inspection surface  134  to the ultrasonic-sensor assembly  104 . Accordingly, the ultrasonic-sensor assembly  104  is open to the inspection surface  134  via the slot  128 . In this manner, access to the ultrasonic-sensor assembly  104  through the inspection surface  134  is unobstructed, which allows ultrasonic signals to transmit to the outer surface  152  of the hat stiffener  150  from the ultrasonic-sensor assembly  104  and to transmit from the outer surface  152  of the hat stiffener  150  to the ultrasonic-sensor assembly  104  without obstruction. As described below, the slot  128  forms part of a fluid chamber  126  that receives fluid, such as water, which acts as an ultrasonic coupling medium to help maintain ultrasonic coupling (i.e., “water coupling”) between the ultrasonic sensor array of the ultrasonic-sensor assembly  104  and the outer surface  152  of the hat stiffener  150 . The inspection surface  134  also forms part of the fluid chamber  126 . 
     The ultrasonic sensor array and the slot  128  are elongated in a lateral direction that is perpendicular to an inspection direction  160  of the probe  100  (see, e.g.,  FIG. 5 ). Moreover, the cap portion  158  of the hat stiffener  150 , the inspection surface  134 , the slot  128 , and the ultrasonic sensor array are curved about an axis parallel with the inspection direction  160  (e.g., curved across the width of the hat stiffener  150 ). Accordingly, the slot  128  extends lengthwise circumferentially along the inspection surface  134 . 
     As shown in  FIG. 1 , the probe  100  additionally includes a surface-engagement assembly  106  that is movably coupled to the body  102  such that the surface-engagement assembly  106  is movable relative to the body  102 . The surface-engagement assembly  106  includes a first foot  108 A and a second foot  108 B. The first foot  108 A is movably coupled to the body  102  on a first lateral side  180 A of the body  102  and the second foot  108 B is movably coupled to the body  102  on a second lateral side  180 B of the body  102  such that, for example, the slot  128  extends lengthwise from proximate the first foot  108 A to proximate the second foot  108 B. Accordingly, the first lateral side  180 A and the second lateral side  180 B of the body  102  are spaced apart from each other by the slot  128  and the first foot  108 A and the second foot  108 B are on opposite ends of the slot  128 . In others, the first foot  108 A and the second foot  108 B, in effect, straddle the slot  128  in an end-to-end manner. Because the surface-engagement assembly  106  is movable relative to the body  102 , the first foot  108 A and the second foot  108 B of the surface-engagement assembly  106  also are movable relative to the body  102 , as well as the ultrasonic-sensor assembly  104  fixed to the body  102 . As explained in more detail below, the first foot  108 A and the second foot  108 B, being movable relative to the body  102  and the ultrasonic-sensor assembly  104 , enable the probe  100  to accommodate differently sized (e.g., radiused) hat stiffeners. 
     The surface-engagement assembly  106  also includes first legs  110 A and second legs  110 B that are movable relative to the body  102  and the ultrasonic-sensor assembly  104 . The first foot  108 A is fixed to inward ends of the first legs  110 A and the second foot  108 B is fixed to inward ends of the second legs  110 B. The first legs  110 A are spaced apart from each other, which enables the body  102  to be interposed between the first legs  110 A. Correspondingly, the second legs  110 B are spaced apart from each other, which enables the body  102  to be interposed between the second legs  110 B. In this manner, the first legs  110 A and the second legs  110 B straddle the body  102  while being movable relative to the body  102 . 
     Outward ends of the first legs  110 A are coupled together, such as by a first bridge  178 A, and outward ends of the second legs  110 B are coupled together, such as by a second bridge  178 B. The first bridge  178 A and the second bridge  178 B promote stability and co-movability between the first legs  110 A and the second legs  110 B, respectively. The first bridge  178  and the first legs  110 A can be separately formed and attached together or co-formed as a one-piece monolithic construction. Similarly, the first foot  108 A can be separately formed from and attached to the first legs  110 A or co-formed as a one-piece monolithic construction with the first legs  110 A. Likewise, the second foot  108 B can be separately formed from and attached to the second legs  110 B or co-formed as a one-piece monolithic construction with the second legs  110 B. 
     Referring to  FIG. 2 , the first legs  110 A includes first retention portions  142 A between the inward and outward ends of the first legs  110 A. Similarly, the second legs  110 B includes second retention portions  142 B between the inward and outward ends of the second legs  110 B. Moreover, the body  102  includes first retaining channels  136 A and second retaining channels  136 B. The first retaining channels  136 A are spaced apart from each other on the first lateral side  180 A of the body  102  and the second retaining channels  136 B are spaced apart from each other on the second lateral side  180 B of the body  102 . Each one of the first retaining channels  136 A and the second retaining channels  136 B define a circumferentially closed channel through which a corresponding one of the first retention portions  142 A and the second retention portions  142 B extends. The first retaining channels  136 A and the second retaining channels  136 B movably (e.g., slidably) retain a corresponding one of the first retention portions  142 A and the second retention portions  142 B extends. In other words, the first retention portions  142 A and the second retention portions  142 B move along the first retaining channels  136 A and the second retaining channels  136 B, respectively, in directions defined by the orientation of the first retaining channels  136 A and the second retaining channels  136 B. As shown in  FIG. 5 , the first retaining channels  136 A are oriented parallel to a first extension direction  162 A and a first retraction direction  164 A and the second retaining channels  136 B are oriented parallel to a second extension direction  162 B and a second retraction direction  164 B. 
     As the first retention portions  142 A and the second retention portions  142 B move along the first retaining channels  136 A and the second retaining channels  136 B, the first foot  108 A and the second foot  108 B correspondingly move. Accordingly, the orientation of the first retaining channels  136 A corresponds with the directionality of the movement of the first foot  108 A and the orientation of the second retaining channels  136 B corresponds with the directionality of the movement of the second foot  108 B. Moreover, because the first retaining channels  136 A and the second retaining channels  136 B are linear, the first foot  108 A and the second foot  108 B are slidable relative to the body  102  along linear paths. 
     In certain examples, the first retaining channels  136 A and the second retaining channels  136 B each have a two-piece construction. For example, a corresponding one of the first retention portions  142 A and the second retention portions  142 B can be positioned into an open portion of one of the first retaining channels  136 A and the second retaining channels  136 B, which is then closed by a second portion, attached to the open portion, to circumferentially close the corresponding retention channel and movably retain the retention portion therein. 
     In some examples, the first legs  110 A and the second legs  110 B are co-movable relative to each other. Accordingly, in such examples, the first foot  108 A and the second foot  108 B are co-movable relative to each other. The surface-engagement assembly  106  includes a crossbar  112 A and a second crossbar  112 B that facilitate co-movement of the first foot  108 A and the second foot  108 B, in certain examples. The crossbar  112 A and the second crossbar  112 B are on opposite sides of the body such that the ultrasonic-sensor assembly  104  is interposed between the crossbar  112 A and the second crossbar  112 B (see, e.g.,  FIG. 3 ). The crossbar  112 A and the second crossbar  112 B span laterally across the body  102  from the first lateral side  180 A of the body  102  to the second lateral side  180 B of the body  102 . The crossbar  112 A and the second crossbar  112 B intercouple the first foot  108 A and the second foot  108 B such that translational movement of the crossbar  112 A and the second crossbar  112 B results in co-movement of the first foot  108 A and the second foot  108 B. 
     Each one of the crossbar  112 A and the second crossbar  112 B includes a first channel  140 A and a second channel  140 B on opposite end portions of the respective one of the crossbar  112 A and the second crossbar  112 B. The first channel  140 A is configured to receive and retain a corresponding one of first pins  138 A of the first legs  110 A. Similarly, the second channel  140 B is configured to receive and retain a corresponding one of second pins  138 B of the second legs  110 B. The first pins  138 A are non-movably fixed to corresponding ones of the first legs  110 A and the second pins  138 B are non-movably fixed to corresponding ones of the second legs  110 B. In some examples, the first pins  138 A and the second pins  138 B are fasteners affixed to and extending from corresponding ones of the legs. 
     The first channel  140 A and the second channel  140 B are elongated such that the first pin  138 A and the second pin  138 B are configured to move along the first channel  140 A and the second channel  140 B, respectively. The first pin  138 A moves along the first channel  140 A in a first outward direction  166 A and a first inward direction  168 A that is opposite the first outward direction  166 A. The second pin  138 B moves along the second channel  140 B in a second outward direction  166 B and a second inward direction  168 B that is opposite the second outward direction  166 B. Moreover, the first channel  140 A and the second channel  140 B are sized to constrain or limit movement of the respective first pin  138 A and the second pin  138 B to lengthwise along the corresponding first channel  140 A and the second channel  140 B. Accordingly, as an example, the pins can slide side-to-side, lengthwise, along the channel, but not up-and-down widthwise along the channel. 
     The crossbar  112 A and the second crossbar  112 B are movably coupled to the body  102  such that movement of the crossbar  112 A and the second crossbar  112 B, relative to the body  102 , is limited to a first direction  122  and a second direction  124 . The first direction  122  is opposite the second direction  124 . Additionally, the first direction  122  and the second direction  124  are perpendicular to the lengthwise movement of the first pins  138 A and the second pins  138 B along the first channels  140 A and the second channels  140 B of the crossbar  112 A and the second crossbar  112 B. 
     Corresponding movement of the crossbar  112 A and the second crossbar  112 B is limited to the first direction  122  and the second direction  124  via slidable engagement between a guiderail slot  170 A of the crossbar  112 A and a guiderail  114 A of the body  102 , on one side of the body, and slidable engagement between a second guiderail slot  170 B of the second crossbar  112 B and a second guiderail  114 B of the body  102 . Accordingly, the guiderail slot  170 A is slidably engaged with the guiderail  114 A such that the guiderail  114 A limits movement of the crossbar  112 A to the first direction  122  and the second direction  124  and the second guiderail slot  170 B is slidably engaged with the second guiderail  114 B such that the second guiderail  114 B limits movement of the second crossbar  112 B to the first direction  122  and the second direction  124 . The guiderail  114 A and the second guiderail  114 B extend lengthwise in the first direction  122  and the second direction  124 . Moreover, the guiderail  114 A and the second guiderail  114 B are nestably received in a respective one of the guiderail slot  170 A and the second guiderail slot  170 B. 
     Referring to  FIGS. 1 and 2 , the probe  100  further includes first biasing mechanisms  120 A and second biasing mechanisms  120 B. The first biasing mechanisms  120 A are coupled to the first lateral side  180 A of the body  102 , at first ends of the first biasing mechanisms  120 A and the surface-engagement assembly  106  at second ends of the first biasing mechanisms  120 A. The second biasing mechanisms  120 B are coupled to the second lateral side  180 B of the body  102 , at first ends of the second biasing mechanisms  120 B, and the surface-engagement assembly  106 , at second ends of the second biasing mechanisms  120 B. More specifically, the second ends of the first biasing mechanisms  120 A are coupled to respective ones of the first legs  110 A and the second ends of the second biasing mechanisms  120 B are coupled to respective ones of the second legs  110 B. The first biasing mechanisms  120 A, being coupled to and extending between the body  102  and the first legs  110 A, are configured to bias the first foot  108 A away from a retracted position (see, e.g.,  FIG. 7 ) and into an extended position (see, e.g.,  FIG. 8 ). Similarly, the second biasing mechanisms  120 B, being coupled to and extending between the body  102  and the second legs  110 B, are configured to bias the second foot  108 B away from the retracted position and into the extended position. 
     According to one example, each one of the first biasing mechanisms  120 A and the second biasing mechanisms  120 B is a spring, such as a compression spring. In the case of a compression spring, when coupled to the outward ends of the legs, the springs are at least partially or not in tension when the first foot  108 A and the second foot  108 B are in the extended position. However, any movement of the first foot  108 A and the second foot  108 B toward the retracted position causes the compression springs to be placed in tension and thus apply a biasing force that urges the first foot  108 A and the second foot  108 B toward the extended direction. Alternatively, when the compression springs are coupled to the inward ends of the legs (e.g., proximate the feet), the springs are at least partially or not in compression when the first foot  108 A and the second foot  108 B are in the extended position. However, any movement of the first foot  108 A and the second foot  108 B toward the retracted position causes the compression spring to be compressed and thus apply a biasing force that urges the first foot  108 A and the second foot  108 B toward the extended direction. The compression springs may include other damping mechanisms or materials, such as damping fluids that control the damping characteristics of the compression springs. In some examples, the first biasing mechanisms  120 A and the second biasing mechanisms  120 B are passive. However, in other examples, the first biasing mechanisms  120 A and the second biasing mechanisms  120 B can be actively controlled. 
     As shown in  FIG. 2 , the first foot  108 A includes a first engagement surface  118 A and the second foot  108 B includes a second engagement surface  118 B. The first engagement surface  118 A is configured to engage the outer surface  152  of the first web portion  156 A of the hat stiffener  150 . Similarly, the second engagement surface  118 B is configured to engage the outer surface  152  of the second web portion  156 B of the hat stiffener  150 . Generally, the first engagement surface  118 A and the second engagement surface  118 B are shaped to complement the shape of the first web portion  156 A and the second web portion  156 B. For example, the first engagement surface  118 A and the second engagement surface  118 B can be shaped such that maximized portions of the first engagement surface  118 A and the second engagement surface  118 B sit flush against the first web portion  156 A and the second web portion  156 B, respectively. Accordingly, in one example where the first web portion  156 A and the second web portion  156 B are planar, the first engagement surface  118 A and the second engagement surface  118 B are planar to sit flush against the first web portion  156 A and the second web portion  156 B. In other examples, the first engagement surface  118 A and the second engagement surface  118 B are contoured to complement a contour of the first web portion  156 A and the second web portion  156 B. 
     Referring to  FIGS. 5 and 7 , translational movement of the crossbar  112 A and the second crossbar  112 B in the first direction  122  away from the inspection surface  134  corresponds with movement of the first foot  108 A in the first retraction direction  164 A toward its retracted position (e.g., a first retracted position A) and movement of the second foot  108 B in the second retraction direction  164 B toward its retracted position (e.g., a second retracted position A′). In contrast, referring to  FIGS. 5 and 8  translational movement of the crossbar  112 A and the second crossbar  112 B in the second direction  124  toward the inspection surface  134  corresponds with movement of the first foot  108 A in the first extension direction  162 A toward its extended position (e.g., a first extended position B) and movement of the second foot  108 B in the second extension direction  162 B toward its extended position (e.g., a second extended position B′). Movement of the first foot  108 A between the first retracted position and the first extended position is along a first path  172 A relative to the body  102  (see, e.g.,  FIG. 7 ). Similarly, movement of the second foot  108 B between the second retracted position and the second extended position is along a second path  172 B relative to the body  102 . 
     The first path  172 A and the second path  172 B are linear in some examples. Moreover, in certain examples, a first angle θ 1  defined between the first path  172 A and the second path  172 B is perpendicular or oblique (i.e., non-parallel). Accordingly, as the first foot  108 A and the second foot  108 B move along the first path  172 A and the second path  172 B in the first extension direction  162 A and the second extension direction  162 B, the first foot  108 A and the second foot  108 B move toward each other. In contrast, as the first foot  108 A and the second foot  108 B move along the first path  172 A and the second path  172 B in the first retraction direction  164 A and the second retraction direction  164 B, the first foot  108 A and the second foot  108 B move away from each other. Also, in some examples, the first foot  108 A is further from the inspection surface  134  in the first extended position than in the first retracted position and the second foot  108 B is further from the inspection surface  134  in the second extended position than in the second retracted position. Such a configuration accommodates different radiuses of different hat stiffeners. 
     Referring to  FIG. 7 , in some examples, the first foot  108 A is fixed to the inward end of the first leg  110 A such that the first engagement surface  118 A is at a second angle θ 2  relative to the first path  172 A. Likewise, in some examples, the second foot  108 B is fixed to the inward end of the second leg  110 B such that the second engagement surface  118 B is at a second-prime angle θ 2 ′ relative to the second path  172 B. The second angle θ 2  is 90-degrees and the second-prime angle θ 2 ′ is 90-degrees in some examples. Angling the first engagement surface  118 A and the second engagement surface  118 B in this manner, helps to ensure an adequate portion of the first engagement surface  118 A and the second engagement surface  118 B contacts the first web portion  156 A and the second web portion  156 B of variously sized hat stiffeners. 
     To accommodate the slot  128 , limit obstruction of the sound waves generated by the ultrasonic-sensor assembly  104  through the slot  128 , and help define a fluid chamber  126 , the first foot  108 A and the second foot  108 B include a first groove  130 A and a second groove  130 B, respectively, formed in the respective first engagement surface  118 A and the second engagement surface  118 B. The first groove  130 A or notch effectively wraps around an end of the slot  128  and the second groove  130 B or notch effectively wraps around an opposite end of the slot  128 . The first groove  130 A and the second groove  130 B enable the first engagement surface  118 A and the second engagement surface  118 B to extend from one side of the slot  128  to an opposite side of the slot  128 . As shown in  FIG. 4 , in plan view, the slot  128  and the ultrasonic-sensor assembly  104  extend lengthwise between the first groove  130 A and the second groove  130 B. 
     As shown in  FIG. 2 , the first foot  108 A includes first beveled edges  174 A and the second foot  108 B includes second beveled edges  174 B. Depending on an inspection direction  160  (see, e.g.,  FIG. 5 ), each one of the first beveled edges  174 A is a corresponding one of a first beveled leading edge or a first beveled trailing edge. As shown, the first beveled leading edge and the first beveled trailing edge (i.e., the first beveled edges  174 A) oppose each other or are on opposite ends of the first foot  108 A. Similarly, depending on the direction of inspection, each one of the second beveled edges  174 B is a corresponding one of a second beveled leading edge or a second beveled trailing edge. As shown, the second beveled leading edge and the second beveled trailing edge (i.e., the second beveled edges  174 B) oppose each other or are on opposite ends of the second foot  108 B. The first beveled edges  174 A and the second beveled edges  174 B are parallel to the lengthwise direction of the slot  128  or perpendicular to the inspection direction  160 . As used herein, the term perpendicular can mean exactly perpendicular (i.e., forming a 90-degree angle) or substantially perpendicular (i.e., within +/−5-degrees of forming a 90-degree angle). 
     Referring to  FIG. 2 , at least a portion of the first engagement surface  118 A and the second engagement surface  118 B, on both sides of the first groove  130 A and the second groove  130 B, is co-extensive with (e.g., immediately adjacent) a portion of the inspection surface  134  of the body  102 . As the first foot  108 A and the second foot  108 B move between the extended and retracted positions, the portions of the first engagement surface  118 A and the second engagement surface  118 B that are co-extensive with the inspection surface  134  changes. However, because as least some portion of the first engagement surface  118 A and the second engagement surface  118 B remains co-extensive with the inspection surface  134  on both sides of the grooves, a substantially continuous fluid boundary is defined along the first engagement surface  118 A, the second engagement surface  118 B, and the inspection surface  134  on both sides of the slot  128 . 
     The continuous fluid boundary along the first engagement surface  118 A, the second engagement surface  118 B, and the inspection surface  134  defines a portion of the fluid chamber  126 . The fluid chamber  126  is open to the ultrasonic-sensor assembly  104  and includes the space defined by the slot  128 . Accordingly, the fluid chamber  126  of the probe  100  is the space or volume defined between the ultrasonic-sensor assembly  104 , the slot  128 , the inspection surface  134 , the first groove  130 A, and the second groove  130 B. Thus, as the first foot  108 A and the second foot  108 B move between the extended and retracted positions, the volume of the fluid chamber  126  changes. 
     Referring to  FIG. 1 , in some examples, the body  102  of the probe  100  additionally includes a first fluid input  144  and a second fluid input  146  both open to the slot  128 . The first fluid input  144  is fluidically coupled to a fluid source and receives fluid from the fluid source. The second fluid input  146  is also fluidically coupled to a fluid source, which can be the same fluid source that is fluidically coupled to the first fluid input  144 , to receive fluid from the fluid source. During non-destructive inspection of the hat stiffener  150  with the probe  100 , fluid, from the fluid source, is transferred from the first fluid input  144  and the second fluid input  146  into the fluid chamber  126 . In this manner, fluid is circulated through the fluid chamber  126 . The fluid in the fluid chamber  126  at any given time helps facilitate the transmission of sound waves from the ultrasonic-sensor assembly  104  to the outer surface  152  of the cap portion  158  of the hat stiffener  150 . More specifically, the fluid chamber  126  serves to transmit sound from the ultrasonic sensor into the part and then back to the sensor. Maintaining fluid coupling between the part and sensor at all times during an inspection helps generate acceptable data. In some examples, the fluid is any fluid capable of providing a coupling medium through which sound waves travel more efficiently than air. In some examples, the fluid is water. In other examples, the fluid can be a gel or an oil. 
     The probe  100  is manually or autonomously moved along the outer surface  152  of the hat stiffener  150  during a non-destructive inspection process. In some examples, the probe  100  is part of a handheld tool that a user grasps and manually moves long the hat stiffener  150 . According to alternative examples, the probe  100  is part of an autonomously-driven tool that autonomously moves the probe  100  along the hat stiffener  150 . Referring to  FIG. 6 , a system  200  for non-destructively inspecting the hat stiffener  150  includes a robotic arm  202 . The probe  100  is fixed to the robotic arm  202 . Generally, the robotic arm  202  is configured to autonomously move the probe  100  along the hat stiffener  150  such that at least a portion of the inspection surface  134  of the body  102  contacts the hat stiffener  150  and the first foot  108 A and the second foot  108 B, in first positions relative to the body  102  and the ultrasonic-sensor assembly  104 , contact the hat stiffener  150 . 
     According to some examples, the system  200  is configured to inspect hat stiffeners of various sizes. In one example, the robotic arm  202  is configured to autonomously remove the probe  100  from the hat stiffener  150 , which can be considered a first hat stiffener with a first radius r 1 , and autonomously move the probe  100  along a second hat stiffener, having a second radius r 2  that is different than the first radius r 1 , such that at least a portion of the inspection surface  134  of the body  102  contacts the second hat stiffener and the first foot  108 A and the second foot  108 B, in second positions relative to the body  102  and the ultrasonic-sensor assembly  104 , contact the second hat stiffener  150 . The first positions are different than the second positions. In an example, the hat stiffener  150  illustrated in  FIG. 7  is the first hat stiffener, and the hat stiffener  150  illustrated in  FIG. 8  is the second hat stiffener. 
     The robotic arm  202  can be any of various automated robots. In some examples, the robotic arm  202  includes a footing and multiple articulating members, such as a base that is rotatable relative to the footing about a vertical axis, a connecting arm that is pivotable relative to the base about a horizontal axis, a support arm that is pivotable relative to the connecting arm about a horizontal axis, an end-effector extension arm that is rotatable relative to the support arm about a support axis, an end-effector coupler arm that is pivotable relative to the end-effector extension arm, and an end-effector interface arm that is rotatable and to which the probe  100  is co-movably fixed. Accordingly, in some examples, the robotic arm  202  is a 6-axis robot that facilitates motion of the probe  100  with 6-degrees of freedom. However, in other examples, the robotic arm  202  can have fewer or more than 6-degrees of freedom. 
     Referring to  FIG. 9 , according to some examples, a method  300  of using the probe  100  to non-destructively inspect one or more hat stiffeners, such as the hat stiffener  150 , is shown. The method  300  includes (block  302 ) contacting the cap portion  158  of the hat stiffener  150  with at least a first portion of the inspection surface  134  of the body  102  of the probe  100 . The method  300  also includes (block  304 ) moving the first foot  108 A of the probe  100 , relative to the body  102 , to contact the first web portion  156 A of the hat stiffener  150  when the inspection surface  134  is contacting the cap portion  158  of the hat stiffener  150 . The method  300  additionally includes (block  306 ) moving the second foot  108 B of the probe  100 , relative to the body  102 , to contact a second web portion  156 B of the hat stiffener  150  when the inspection surface  134  is contacting the cap portion  158  of the hat stiffener  150 . In certain examples, the first foot  108 A is moved along the first path  172 A and the second foot  108 B is moved along the second path  172 B. The method  300  further includes (block  308 ) ultrasonically inspecting the cap portion  158  of the hat stiffener  150  with the ultrasonic-sensor assembly  104 , which is fixed to the body  102  and open to the inspection surface  134  via the slot  128 . In some examples, the cap portion  158  is ultrasonically inspected at block  308  while the probe  100  is moved along the hat stiffener  150 . 
     In some examples, prior to ultrasonically inspecting the cap portion  158  at block  308 , the method  300  also includes (block  310 ) filling the fluid chamber  126  of the probe  100  and (block  312 ) changing a volume of the fluid chamber  126  by moving the first foot  108 A relative to the body  102  and moving the second foot  108 B relative to the body  102 . 
     The method  300  additionally includes (block  314 ) biasing the first foot  108 A away from the inspection surface  134  and toward the second foot  108 B and (block  316 ) biasing the second foot  108 B away from the inspection surface  134  and toward the first foot  108 A. Biasing the first foot  108 A and the second foot  108 B toward each other helps to ensure contact between the first foot  108 A and the first web portion  156 A and the second foot  108 B and the second web portion  156 B of hat stiffeners having cap portions  158  with different radiuses. In certain examples, the first foot  108 A and the second foot  108 B are co-movably coupled such that movement of one of the first foot  108 A and the second foot  108 B causes movement of the other of the first foot  108 A and the second foot  108 B. Co-movement and equal biasing of the first foot  108 A and the second foot  108 B facilities self-centering of the probe  100  on the hat stiffener  150 . 
     In certain examples, the method  300  includes steps associated with inspecting two or more hat stiffeners with different radiuses. According to block  304  of the method  300 , the first foot  108 A and the second foot  108 B can be in first positions, relative to the body  102 , when in contact with the first web portion  156 A and the second web portion  156 B, respectively, of a first hat stiffener and when the inspection surface  134  of the body  102  is in contact with the cap portion  158  of the first hat stiffener. The method  300  can additionally include removing the probe  100  from the first hat stiffener and contacting the cap portion of a second hat stiffener with at least a second portion of the inspection surface  134  of the body  102  of the probe  100 . The method  300  can further include moving the first foot  108 A of the probe  100 , relative to the body  102 , into a second position to contact the first web portion of the second hat stiffener when the inspection surface  134  is contacting the cap portion of the second hat stiffener, moving the second foot  108 B of the probe  100 , relative to the body  102 , into a second position to contact a second web portion of the second hat stiffener when the inspection surface  134  is contacting the cap portion of the second hat stiffener, and ultrasonically inspecting the cap portion of the second hat stiffener with the ultrasonic-sensor assembly  104 . The radius of the cap portion of the first hat stiffener is different than the radius of the cap portion of the second hat stiffener, and the first positions are different than the second positions. 
     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.” 
     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.