Patent Publication Number: US-11660146-B2

Title: Navigation system and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 15/957,539, filed on Apr. 19, 2018, which claims the benefit of U.S. Provisional Application No. 62/487,801, filed on Apr. 20, 2017. The entire disclosure of each of the above applications are incorporated herein by reference. 
    
    
     FIELD 
     The subject disclosure relates generally to a system for generating a field, and particularly to a system and arrangement to generate a selected electro-magnetic field. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     In a navigation system for various procedures, such as surgical procedures, assembling procedures, and the like, an instrument or object may be tracked by measuring an effect of a magnetic field on a sensor coil. The sensor coil may include a conductive material that is placed within a magnetic field where a current is induced on the coil. The measured induced current may be used to identify or determine a location of the instrument or object. Determining the location of a coil, however, may be desired to be enhanced in various aspects. 
     The electro-magnetic field or fields may be generated with a plurality of purposefully positioned and oriented transmit coils. Various transmitter or field generation systems include the AxiEM™ electro-magnetic navigation system sold by Medtronic Navigation, Inc., having a place of business in Louisville, Colo. The AxiEM™ electro-magnetic navigation system may include a plurality of transmit coils that are used to generate one or more electro-magnetic fields that are sensed by a tracking device, which may be sensor coil, to allow a navigation system, such as a StealthStation® surgical navigation system to be used to track and/or illustrate a tracked location of an instrument. 
     The transmit coils positioned and oriented about one another generally fill a volume smaller than a navigation volume generated by the transmitting coils. The volume including the transmitting coils, however, is generally positioned near the patient so that the navigation field or volume encompasses a region of the patient in which navigation would occur. Accordingly, the transmitter coil array may be near an individual, such as a surgeon, performing a procedure. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     Disclosed is a localizer, which may include a transmitting assembly, particularly a transmitting coil array (TCA), and a field shaping assembly that is configured and is operable to transmit one or more diverse magnetic field or fields. Particularly, the localizer is configured to generate field vectors that are highly diverse relative to one another with a relatively orthogonal or near orthogonal distribution of measurable vectors relative to an origin or within a volume. The diversity of one or more fields is generated even though a plurality of coils of the TCA are positioned on a substantially flat plane. The accuracy, precision, and reliability of a determined location of a sensor, such as a coil, may be improved with additional measurements, particularly additional measurements of effects of one or more of the diverse magnetic fields on a sensor coil. 
     The localizer may be formed of a plurality of cooperative features including the transmitting/transmitter coil array (TCA) including one or more transmitting coils and a field shaping assembly. The field shaping assembly is provided to include a plurality of portions or members that separately interact with the magnetic field produced by one or more of the coils. For example, a plurality of coils may be formed as one or more trios or triplets of coils that are all powered to generate a field. A field shaping segment may be provided to interact substantially individually with the field. The TCA, therefore, may generate or form a generated navigation field in a navigable volume that may substantially mimic a field created by co-center positioned and orthogonally oriented coils. The TCA, therefore, may include a substantially low profile, or flat configuration, and be positioned near or adjacent a location without being intrusive in an operating theater. For example, the TCA may be positioned under a patient or between a patient and a support structure. 
     The field shaping assembly may be included with or fixed relative to the TCA. The TCA and field shaping assembly may also be referred to as a localizer. The field shaping assembly may be used to affect a generated field to create the second field configuration for ensuring a diversity of the field. The field shaping assembly may also acts to mitigate or eliminate effects of external conductive surfaces and materials, such as conductive metal, which may be present in a support structure or in other structures away from the localizer. For example, the TCA may be positioned on a surgical operating bed that may include metal or other conductive materials where the field shaping assembly ensures that the conductive materials do not affect or substantially affect the field produced by the localizer. In various embodiments, substantially affecting the field produced by the localizer may include where a conductive material may be present near the localizer, but no compensation (e.g. processing or algorithmic compensation) need occur to allow for an appropriate and accurate tracking of a selected tracking device. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG.  1    is an exploded view of a localizer; 
         FIG.  2 A  is a top view of a coil of a transmitting coil array; 
         FIG.  2 B  is a side plan view of the coil  FIG.  2 A ; 
         FIG.  3    is a top plan view of a localizer structural component; 
         FIG.  3 A  is a detailed view of a coil holding portion of the structural component; 
         FIG.  3 B  is a cross-sectional detailed view of a coil holding region of the structural component; 
         FIG.  4    is a cross-sectional view along line  4 - 4  of  FIG.  3   ; 
         FIG.  4 A  is a detailed cross-sectional view of  FIG.  4   ; 
         FIG.  5 A  is a plan view of a field shaping assembly; 
         FIG.  5 B  is a cross-sectional view of a conductive member; 
         FIG.  5 C  is a cross-sectional view of the magnetically permeable member; 
         FIG.  6    is a schematic view of a localizer including representative field lines; 
         FIG.  7    is an exemplary graphical illustration of diversity of a magnetic field generated with the localizer; 
         FIG.  8    is a flowchart including steps for navigating an instrument; 
         FIG.  9    is an environmental view of a navigation system; 
         FIG.  10 A  illustrates a field shaping assembly, according to various embodiments; 
         FIG.  10 B  is a cross-section of  FIG.  10 A ; 
         FIG.  10 C  is a cross-section of a field shaping assembly and a coil, according to various embodiments; 
         FIG.  10 D  is a cross-section of a field shaping assembly and a coil, according to various embodiments; 
         FIG.  11 A ,  FIG.  11 B , and  FIG.  11 C  illustrate a field shaping assembly with a single coil, according to various embodiments; 
         FIG.  12 A  and  FIG.  12 B  illustrate field shaping assemblies with a plurality of coils positioned relative thereto, according to various embodiments; and 
         FIG.  13    illustrates a field shaping assembly including a plurality of coils positioned relative thereto, according to various embodiments. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     A navigation system  10  ( FIG.  9   ), which may include a localizer assembly or system  20  as illustrated in  FIG.  1   , may be used for various purposes or procedures. A navigation system may be used to determine or track a location of an instrument in a volume. Tracking a location of an instrument may assist a user in determining a location of the instrument, even if the instrument is not directly viewable by the user. A location may include at least one three-dimensional position (e.g. X, Y, or Z coordinates) and at least one orientation (e.g. yaw, pitch, and roll). In various embodiments, therefore, location may include six-degrees of freedom. Various procedures may block the view of the user, such as performing a repair or assembling an inanimate system, such as a robotic system, assembling portions of an airframe or an automobile, or the like. Various other procedures may include a surgical procedure, such as performing a spinal procedure, neurological procedure, positioning a deep brain simulation probe, or other surgical procedures on a living subject. In various embodiments, for example, the living subject may be a human subject and the procedure may be performed on a human patient. 
     Nevertheless, in various embodiments, a surgical navigation system  10  ( FIG.  9   ), as discussed further herein, may incorporate a various portion such as those disclosed in U.S. Pat. Nos. RE44,305; 7,697,972; 8,644,907; and 8,842,893; and U.S. Pat. App. Pub. Nos. 2004/0199072, all incorporated herein by reference. Various components of a surgical navigation system may include an imaging system that is operable to image a patient, such as an O-arm® imaging system, magnetic resonance imaging (MRI) system, computed tomography system, etc. Images may either be acquired during a surgical procedure or acquired prior to a surgical procedure for displaying on a display device. An instrument may be tracked in a trackable volume or a navigational volume that is produced by a transmitter or transmitting coil array that is incorporated into a localizer  20 , as illustrated in  FIG.  9   . 
     With reference to  FIG.  1   , the localizer  20  may be an electro-magnetic (EM) localizer that is operable to generate electro-magnetic fields with a transmitting coil array  30 . The coil array  30  may include one or more coil groupings or arrays such as a first grouping  34 , a second grouping  36 , and a third grouping  38 , and a fourth grouping  40 . Each of the groupings may include three coils, also referred to as trios or triplets. For example, the first grouping  34  may include a first coil  34   a , a second coil  34   b , and a third coil  34   c . Similarly, the second grouping  36  may include a first coil  36   a , a second coil  36   b , and a third coil  36   c . The third grouping  38  may include first coil  38   a , a second coil  38   b , and a third coil  38   c . A fourth grouping  40  may include a first coil  40   a , a second coil  40   b , and a third coil  40   c . The coils may be powered to generate or form an electro-magnetic field by driving current through the coils of the coil groupings  34 ,  36 ,  38  and  40 . As the current is driven through the coils, the electro-magnetic fields generated will extend away from the coils  34 ,  36 ,  38 , and  40  and form a navigation domain or volume  41  (e.g. as illustrated in  FIG.  6   ). 
     The navigation domain or volume generally defines a navigation space or patient space. As is generally understood in the art, an object or instrument  50 , such as a dill, lead, etc., may be tracked in the navigation domain relative to a patient or subject with an instrument tracking device  52 . For example, the instrument  50  may be freely moveable, such as by a user, relative to a dynamic preference frame (DRF) or reference frame tracker  54  that is fixed relative to the subject. Both the tracking devices  52 ,  54  may include sensing coils (e.g. formed as coiled conductive material sensors) that sense and are used to measure a magnetic field strength, etc. Due to the tracking device  52 , connected or associated with the instrument  50 , relative to the DRF  54  the navigation system  10  may be used to determine location of the instrument  50  relative to the DRF  54 . The navigation volume or patient space may be registered to an image space of the patient and an icon representing the instrument  50  may be superimposed on the image. Registration of the patient space to the image space and determining a location of a tracking device, such as the tracking device  52 , relative to a DRF, such as the DRF  54  may be performed as is generally known in the art, including as disclosed in U.S. Pat. Nos. RE44,305; 7,697,972; 8,644,907; and 8,842,893; and U.S. Pat. App. Pub. Nos. 2004/0199072, all incorporated herein by reference. 
     With continuing reference to  FIG.  1   , the localizer  20  may further include a printer circuit board (PCB)  60  that includes traces thereon from a cable connector  62  to which a communication or power cable  64  may be connected. The traces on the PCB  60  may connect the cable  64  with individual cable connectors  66 ,  68 ,  70 , and  72 . The connectors may include leads or wires that may be connected to each of the coils in coil groups  34 ,  36 ,  38 , and  40 . Accordingly, the coils in coil groups  34 ,  36 ,  38 , and  40  may be powered or driven by power provided through the traces on the PCB  60  to each of the coils in coil groups  34 ,  36 ,  38 , and  40 , from a navigation processor system  76 . The navigation processor system may include those disclosed in U.S. Pat. Nos. RE44,305; 7,697,972; 8,644,907; and 8,842,893; and U.S. Pat. App. Pub. Nos. 2004/0199072, all incorporated herein by reference, or may also include the commercially available StealthStation® or Fusion™ surgical navigation systems sold by Medtronic Navigation, Inc. having a place of business in Louisville, Colo. 
     The localizer  20  further includes a field shaping assembly  80 . The field shaping assembly  80  may generally include a first magnetically permeable portion that is also substantially nonconductive  82 , a spacer  86  which may be substantially inert, and a substantially conductive portion  90 . The magnetically permeable magnetic portion  82  may include various properties, such as being generally highly magnetically permeable, substantially nonconductive, high magnetic saturation, low magnetic coercivity, as discussed further herein. The spacer member  86  is substantially inert relative to an electric current and a magnetic field and may include a polymer or plastic material such as a polycarbonate having a thickness of about 0.001 millimeters (mm) to about 10 mm, including about 1.0 mm. The thickness of the spacer  86  generally defines a distance between the magnetically permeable member  82  and the conductive member  90 . The magnetically permeable magnetic portion  82  may be provided as four individual portions or members  82   a ,  82   b ,  82   c , and  82   d , as discussed further herein. The individual members may be positioned near each of the coil groups  34 ,  36 ,  38 , and  40  and near corners of the conductive member  90 . The conductive member or portion  90  generally includes a highly conductive material such as a high purity copper or other appropriate highly conductive material. The conductive member  90  may allow generation of eddy currents formed by induced currents due to magnetic fields permeating into the conductive material  90 . 
     The localizer  20  may further include two shells or cover portions including a first cover portion  100  and a second cover portion  104 . The two cover portions enclose all of the coil array  30 , the field shaping assembly  80 , and a structural or holding component  110 . Further, various feet or non-skid elements  116  may be adhered or connected to the case portion  104  for selected operational uses. Moreover, the case, such as the first case portion  100  may include select ergonomic and carrying portions including a hand hole or region  120  and shaped ergonomic portions. Shaped portions may include a neck support region  124  having lower or indent portions  126  and  128  to assist in holding or positioning a head or neck region of a patient or subject for selected procedures. It is understood, however, that the shape and configuration of the cover  100  may be formed in any appropriate shape. Further, the localizer  20  may have selected dimensions of length  20   a , width  20   b , and height  20   c . The length  20   a  may be about 400 mm to about 600 mm, including about 450 mm to about 550 mm, including about 510 mm. The width  20   b  may be about 400 mm to about 500 mm, including about 3000 mm to about 400 mm, including about 355 mm. The height  20   c  may be about 10 mm to about 55 mm, including about 20 mm to about 50 mm, including about 35 mm. With continued reference to  FIG.  1    and additional reference to  FIG.  2 A  and  FIG.  2 B , the coil array  30  includes the plurality of individual coils, as discussed above. The plurality of coils may be formed into the coil groups  34 - 40 . Each of the coils include various features, as described herein. Further, each coil may include substantially identical or similar features, which will not be repeated for clarity. Thus, an exemplary discussion of coil  34   a  will be made and it is understood that the other individual coils will have the same or similar features unless otherwise stated. 
     The coil  34   a  may be formed substantially as an ellipsis having a major axis  150  and a minor axis  154 . The coil  34   a  may be formed on a mold or form and then removed as including substantially only the coiled with or conductive portions. The coil, however, may include the dimensions as discussed herein. The coil  34   a  may, alternatively or in combination, be formed or wound on a bobbin or wire holder. As illustrated in  FIG.  2 B , the wire may be wound on a bobbin or holder and the combination may be inserted in the structural component  110 . 
     The major axis  150  may include an internal major axis portion  150   a  having a dimension, such as a length, of about 20 millimeters (mm) to about 50 mm, including about 31 mm to about 35 mm, and further including a dimension of about 33 mm. The major axis  150  may further an external major axis  150   b , which includes the internal dimension  150   a , that may include a dimension of about 40 mm to about 70 mm, further about 45 mm to about 55 mm, and further including about 50 mm. Thus, along the external major axis  150   b  the coil  34   a  may be about 55 mm long. 
     The minor axis  154  may also include an internal dimension or length of  154   a  and an external dimension or length  154   b , wherein the external dimension  154   b  includes the internal dimension  154   a . The internal dimension  154   a  may be about 5 mm to about 20 mm, including about 9 mm to about 11 mm, and further including about 10.5 mm. The external dimension of  154   b  may be about 20 mm to about 40 mm, further including about 22 mm to about 32 mm, and further including about 27 mm. In various embodiments the coil  34   a  may include an external major axis dimension  150   b  of about 50 mm and an internal dimension of  150   a  of about 33.68 mm. Further, the coil  34   a  may include a minor axis interior dimension  154   a  of about 10.68 mm and an external dimension  154   b  of about 27.5 mm. 
     It is understood that each of the coils of the coil groups  34 ,  36 ,  38 , and  40  may be substantially identical. Accordingly, each of the coils of the coil groups  34 - 40  may include dimensions substantially identical to those discussed above. 
     Further, the coils, such as coil  34   a , may be formed by winding selected connective material, such as 21 gage copper magnet wire wound around an outer dimension of the internal major and minor axes. The wire may generally conform to NEMA MW-136C standards. Further, generally the wire may have a single layer of bonded polyurethane nylon insulation. The coil  34   a  may be formed by winding a pair of leads of the wire. The wire may come to the coil  34   a  as a twisted pair lead  153 , but is not twisted when wrapped around the major and minor internal dimension of the coil as wraps or coil portions  155 . The number of windings may include about 5 to about 10 wraps per layer and about 8-15 layers. In various embodiments the coils may include 7 wraps per layer and 12 layers. As discussed above, the external dimensions of the external major and minor axes  150   b ,  154   b  may be equal to the external 
     As discussed herein, the combination of the TCA  30  with the selected field shaping components  80  may be used to form a selected field geometry and diversity, as also discussed further herein. The field volume may include a navigable or navigation volume, the navigation volume may be about 400 mm 3  to about 600 mm 3 , including about 500 m 3 . The navigation field or volume may begin about 50 mm above the TCA  30 . It is understood by one skilled in the art that the coils, such as the coil  34   a , may be altered depending upon the specifications (e.g. size, type, materials, etc.) of the remaining field shaping components. However, it is understood that the coil  34   a  may be substantially identical to each of the other coils in the coil array  30  when positioned in the localizer  20 . 
     Each of the coils of the coil groups may be positioned in or on the structural component  110 . The structural component  110  may be made of selected materials that generally are inert and do not interact with a magnetic field. Further, the structural component may be made of a non-conductive material. The structural component generally also includes a selected rigidity to provide structural support to the localizer  20 . 
     Accordingly, with continuing reference to  FIG.  1   , and additional reference to  FIGS.  3 - 3 B , the structural component  110  will be discussed in greater detail. The structural component  110  may include a plurality of coil holding regions or portions  160 , such as twelve coil holding regions  160   a ,  160   b ,  160   c ,  160   d ,  160   e ,  160   f ,  160   g ,  160   h ,  160   i ,  160   j ,  160   k , and  160   l . Again, each of the coil holding regions  160   a - 160   l  may be configured to form or provide the coil groups  34 - 40 , as discussed above. Accordingly, each of the groupings may include three coils, as illustrated in  FIG.  3   . For the following discussion, therefore, it is understood that the separate coil groupings may include similar features and components as those discussed below and illustrated in  FIG.  3   , but are not repeated for clarity of the current discussion. The structural component may have a dimension to fit within the overall dimensions of the localizer  20 , including a length  110   a  of about 450 mm to about 550 mm, including about 450 mm and a width of about 350 mm to about 450 mm, including the width of about 350 mm. The dimensions of the portions containing the coil holding regions or portions  160  may be less than the overall dimensions of the structural component  110  and may be about 330 mm to about 370 mm by about 430 mm to about 470 mm, including about 350 mm by about 450 mm. 
     With reference to coil holding regions  160   a ,  160   b ,  160   c , each of these may respectively hold the coils  34   a ,  34   b  and  34   c . Each coil holding region, such as the coil holding region  160   a , illustrated in  FIGS.  3 A and  3 B , may include a raised outer wall  164  that may substantially hold the respective coil  34   a  in place. Further, a central peg or projection  166  may pass through the central portion  156  of the coil, such as the coil  34   a . The peg  166  extends from a floor or bottom surface  186  of the coil holding region  160   a . As discussed above, the major internal axis  150   a  and minor internal axis  154   a  may define the opening  156  of the coil  34   a  or a bobbin holding the coiled portions. The projection  166  may pass into or through the opening  156  and the external wall  164  may be near an external surface  158  of the coil  34   a  or a bobbin holding the coiled portions. Again, it is understood that each coil holding region of the multiple coil holding regions  160  may include similar features. 
     The coil grouping, such as the first coil group  34 , may be positioned around a central point or region  170 . The center point or region  170  may be a center point around which each of the coils  34   a ,  34   b ,  34   c  are positioned. Generally, each of the coils  34   a ,  34   b ,  34   c  are radially spaced from the center  170 . The coils  34   a ,  34   b ,  34   c , however, may not all be equally spaced from the center  170  and/or each other. The coils may each be specifically spaced from an edge of the magnetically permeable member over which the respective coil group is placed. In various embodiments, the respective holding regions  160   a ,  160   b , and  160   c  may be positioned at a selected “clocking angle” relative to one another, such as about 120° from one another around the center  170 . It is understood, however, that the respective holding regions  160   a ,  160   b , and  160   c  need not be 120°, or that all need not be 120° apart. 
     In various embodiments, for example, the coil holding region  160   b  may be on an axis or line  172  extending through the center of the coil holding region  160   b  and the center  170 . Similarly, a second axis or line  174  may extend through the center point  170  and a center of the coil holding region  160   c . An angle  176  between the two lines  172  and  174  and the angle may be about 120°. It is understood, however, as noted above, that the positioning of the coil holding regions relative to one another may be selected to achieve a selected type of field, such as the appropriate diversity in a field, and, therefore, may be altered from the current illustration. Nevertheless, the coil regions of each of the coil groups  34 ,  36 ,  38 , and  40  may be formed to hold the respective coils at about 120° from one another around the center point  170 . Further, as discussed above and herein, diversity may include diversity relative to time based on a transmitted field from the coil groups and an induced current field from the conductive member  90 . Diversity of the field(s) assists in ensuring accurate and/or precise tracking of a selected tracking device. 
     In various embodiments, the respective coils  34   a ,  34   b , and  34   c , in the holding regions  160   a ,  160   b , and  160   c  may be spaced a selected distance from an edge of the respective magnetically permeable member  82  over which they are placed. The distance may be of an outside edge of the coil to a nearest edge of the magnetically permeable member. The distance may be about 1 mm to about 50 mm, including about 2 mm to about 40 mm, and further 10 mm to about 40 mm, and further including about 20 mm to about 25 mm. Another distance may be of an outside edge of the coil to a farthest edge of the magnetically permeable member. This distance may be about 30 mm to about 120 mm, including about 50 mm to about 100 mm. 
     In various embodiments, in additional to and/or in combination with those discussed above, the respective coils  34   a ,  34   b , and  34   c , in the holding regions  160   a ,  160   b , and  160   c  may be spaced a selected distance from a corner and/or edges of the respective magnetically permeable member  82  over which they are placed. The respective coils  34   a ,  34   b , and  34   c  and/or the holding regions  160   a ,  160   b , and  160   c  may be positioned around the common center  170 . A center of the coils  34  and/or the center  166   a  of the coil holding regions  160  may be placed about 10 mm to 50 mm including about 30 mm to about 40 mm from the common center  170 . Further, the center of the coils  34  and/or the center  166   a  of the coil holding regions  160  may be spaced apart at a distance of about 20 mm to about 100 mm including about 50 mm to about 80 mm from each other. Also, the center of the coils  34  and/or the center  166   a  of the coil holding regions  160  may be a distance from a nearest boundary edge of the magnetically permeable member  82 , the distance may be about 20 mm to about 100 mm including about 40 mm to about 70 mm from the nearest boundary. The center of the coils  34  and/or the center  166   a  of the coil holding regions  160  may sit about 80 degrees to about 160 degrees including about 120 degrees around the common center  170 . One of the coil centers may sit about 0 degrees to about 20 degrees from a diagonal of the magnetically permeable member  82 . The long or major axis  150  axes of the coil  34   a  may vary from about 0 to about 90 degrees to the nearest boundary line or tangent line of the magnetically permeable member  82 . It is understood that each of the coils of the various coil groups  34 ,  36 ,  38 , and  40  may be configured as discussed above. Further, each may be varied to achieve a selected field geometry. 
     With continuing reference to  FIG.  3    and with further reference to  FIG.  3 B , the coil holding regions may also include a geometry relative to a substantially flat plane  184 . As discussed further herein, the flat plane  184  may be any appropriate plane, such as one defined by a surface of the field shaping portion  80 , especially defined by a surface of the magnetically permeable portion  82 . 
     The coil holding region  160   c  may include a bottom surface  186 , as also illustrated in  FIG.  3   , upon which the coil, such as the coil  34   c , may rest when positioned in the structural component  110 . The bottom surface  186  of the coil holding portion  160   c  contacts or holds the coil  34   a  in a position and orientation, the bottom surface  186  may define a plane  190  that orients or positions the coil  34   a  relative to the plane  184 . The plane  190  may be parallel or at an angle that will intersect the plane  184 , such as about zero degrees (°) to about 70°, including about 90°, further including about 0° to about 60°. In various embodiments, the plane  190  defined by the bottom surface  186  may extend at an angle  192  relative to a line  194  that is normal to the bottom plane  184 . The angle  192  may be about zero degrees (°) to 180°, including about 90° and further including about 30° to about 150°, including about 90°. In various embodiments, each of the coil holding regions  160   a - 160   l  may include the angle  192  that is the same, in various embodiments, however, at least one of the holding regions  160   a - 160   l  may include the angle  192  that is different from the others. Further, it is understood that the bottom surface  186  of the respective coil holding regions  160   a - 160   l  may tilt along the major axis of the respective coil, the minor axis of the respective coil, or a combination thereof. In various embodiments, therefore, the coil  34   a  may be positioned relative to the plane  184  in any appropriate angle. Thus, the coil  34   a  may not have a top or bottom surface that is substantially parallel with the plane  184 . Rather, the coil  34   a , may be tilted relative to the plane  184 . As discussed further herein, the positioning of the coil  34   a  relative to the plane  184  may be a position of the coil  34   a  relative to a plane defined by the magnetically permeable field shaping portion  82  to assist in forming or generating a selective field diversity. Again, as discussed above, each coil holding portion  160  may include similar or identical features and dimensions, as discussed above. 
     With additional reference to  FIG.  4    and  FIG.  4 A , and continuing reference to  FIG.  3   , the structural component  110  includes a field shaping assembly contact or holding side  114  that is opposite the coil holding side  112 . The field shaping assembly holding side  114  of the structural component  110  may include various features such as a main or expansive pocket  200  that has a main surface or base surface  202  and a wall  204  that extends from the main surface  200 . The wall  204  may assist in holding the conductive member  90  relative to the coil array  30 . The conductive member  90  is formed as or configured as a single (e.g. one) piece of material. In various embodiments, the conductive member  90  may be formed as a plurality of members that are electrically connected or electrically isolated over the entire surface of the expansive pocket  200 . 
     The coils of the coil array  30  are held in the coil holding portions  160   a - 160   i  while the main surface  202  and the upstanding wall  204  assist in holding the conductive member  90  relative to the coil array  30 . The upstanding wall  204  may have a dimension that is substantially equivalent to or has an interference fit with the conductive member  90 . Further, various adhesives or holding materials or members (e.g., rivets, screws, or the like) may be used to fix or hold the conductive member  90  relative to the structural component  110 . 
     The structural component  110  may further include a pocket  220 , which may be referred to as a small or coil group pocket  220 . The small pocket  220  may include a main surface  222  and an upstanding wall  224 . The upstanding wall may extend from the main surface  222  to the surface  202  of the conductive pocket  200 . The upstanding wall  224  may have a dimension that is substantially equivalent to an exterior dimension of the magnetically permeable component  82 . The spacer component  86  may have a dimension that is equal to or slightly larger than the upstanding wall  224 . Therefore, the conductive member  90  may press the spacer component  86  onto the magnetically permeable component  82  and the surface  202  of the conductive pocket  200  to assist in holding the spacer material  86  in place. Further, a force may be applied against the magnetically permeable component  82  as the conductive member  90  is pressed against the spacer component  86 , which, in turn presses against the magnetically permeable component  82  into the small pocket  220 . 
     It is understood that each of the coil groupings, including the coil grouping  34 ,  36 ,  38 , and  40  may each include a separate pocket. As illustrated in  FIG.  1   , and discussed further herein, the magnetically permeable component  82  may be formed as an individual unit or member (or laminated members of the same perimeter dimensions) for each of the coil groups or trios  34 ,  36 ,  38 , and  40 . Accordingly, each magnetically permeable component  82  may be positioned in a separate one of the pocket  220 . The structural component  110  by defining or forming the pockets  220 , therefore, may provide a physical spacing between each of the magnetically permeable component  82 . Generally, the pockets  220  are formed to hold the magnetically permeable members  82  near the coil group  34 , but not in contact with another magnetically permeable member  82 . The magnetically permeable members  82  may be spaced a distance  330 ′,  330 ″ ( FIG.  5 A ) apart. The distances  330 ′,  330 ″ may be about 1 mm to about 200 mm apart including about 1 mm to about 100 mm apart, including about 10 mm apart. 
     It is understood that each of the elements, including the TCA  30  the magnetically permeable component  82 , spacer  86 , and electrically conductive member  90  may be adhered or affixed to the structure component  110  in a selective manner. For example, an adhesive or epoxy, such as Locktite® brand adhesive or epoxy may be used to fix all or portions of the coils and field shaping components  80  to the structural component  110 . Accordingly, each coils of the TCA  30  and the field shaping components  80  may be substantially fixed in a three-dimensional space relative to one another when affixed to the structural component  110 . 
     The field shaping assembly members  80 , as illustrated in  FIG.  1   , include various components and members and discussed further herein. As discussed above the TCA  30 , including the various individual coil members or portions, may be driven to generate an electro-magnetic field. The electro-magnetic field may extend from the TCA  30  as is generally understood by one skilled in the art. As discussed above, the electro-magnetic field may affect tracking devices, such as the instrument tracking device  52  and/or the DRF tracking device  54 . The electro-magnetic field is sensed by the tracking devices  52 ,  54  and a position of the tracking devices  52 ,  54  may be determined relative to one another. The shell or case components  100 ,  104  may be substantially inert and/or not affect the electro-magnetic field. In various embodiments the shell portions  100 ,  104  may be substantially electrically resistive as well. 
     With continued reference to  FIG.  1    and additional reference to  FIGS.  5 - 5 B , the field shaping assembly  80  may include the magnetic or magnetically permeable portion or portions  82 , the substantially inert spacer portions  86 , and the conductive member  90 . As illustrated in  FIG.  1   ,  FIG.  5 A  and  FIG.  5 B , the conductive member  90  may include a first surface  260  that has a surface area. The surface area of the surface  260  may be substantially continuous and extend or be defined by the length of a first edge  262  and a second edge  264 . As is generally understood in geometry, the surface area of the surface  260  may be the two lengths  262 ,  264  multiplied together. 
     The magnetically permeable member  82  may be provided as a plurality of magnetically permeable members  82   a ,  82   b ,  82   c , and  82   d . Each of the magnetically permeable members  82  may be substantially similar or identical in size and may include respective first surfaces  270   a ,  270   b ,  270   c , and  270   d . Each of the surfaces  270  may include substantially similar surface areas and be bounded by respective edges  274  and  276 . Again, as understood in geometry, the surface area of the respective surfaces  270 , would be the dimension of the edge  274  multiplied by the dimension of the edge  276 . 
     The magnetically permeable members  82  may be sized and dimensioned to be positioned relative to each of the coil groups  34 ,  36 ,  38 ,  40 . For example, with reference to  FIG.  5 A , the coils  32   a ,  32   b , and  32   c  (illustrated in phantom) may be positioned on the structural member  110  on the coil array side  112 . The structural member may separate the coil  34   a ,  34   b ,  34   c  physically from the magnetically permeable member  82   a , but a magnetic field produced by the coil group  34  may be affected by the magnetically permeable member  82   a  and the conductive member  90 . Again, it is understood that the coils  34   a ,  34   b ,  34   c  may be positioned about 120 degrees apart, such that the axis  172  extending through a center of the coil  34   b  and the center  170  and the second axis  174  extending through the center  170  and the center of the coil  34   a  are positioned at the angle  176  from one another. The angle  176  allows each of the coils  34   a ,  34   b ,  34   c  to be positioned around the center  170  separated by about 120°. 
     It is further understood that the spacers  86  may be positioned between the conductive member  90  and each of the magnetically permeable members  82   a ,  82   b ,  82   c , and  82   d . It is understood that the spacer  86  may be provided as a large single spacer member that has a surface area that covers an area equivalent to an exterior dimension defined by all of the magnetically permeable members  82  and/or the conductive member  90 , alternatively or in addition thereto an individual spacer member may be provided for each of the magnetically permeable members  82 . The spacer member  86  is substantially inert to both electrical current and magnetic fields. The spacer member  86 , therefore, may be formed in a manner for efficient assembly and manufacturing, thus one spacer member may be provided for each of the magnetically permeable members  82 , rather than a single large spacer member. 
     The conductive member  90 , with additional reference to  FIG.  5 B , may be selected of an appropriately electrically conductive material. The electrically conductive material may include a copper sheet of high purity, such as copper sheet C101A-02 that meets material standards ASTN F-68. The conductive sheet  90  may be an appropriate thickness  279  such as about 0.5 mm to about 3 mm, including about 1 mm to about 2 mm, and further including about 1 mm. The conductive member  90  may further have the side  262  having a length of about 400 mm to about 500 mm, further including about 420 mm to about 450 mm, further including about 438.5 mm to 439.5 mm, and further including about 439 mm. The edge or side  264  may have a dimension of about 320 mm to about 350 mm, further including about 335 mm to about 345 mm, further including about 338.6 mm to about 339.2 mm, and further including about 338.9 mm. 
     The magnetically permeable members  82  may be selected from any appropriate highly magnetically permeable material that is substantially nonconductive and has high magnetic saturation as well as low magnetic coercivity and low frequency dispersion. For example, the magnetically permeable members may be formed of Finemet® nanoparticle crystalline material sold by Hitachi Metals, Ltd. having a place of business in Tokyo, Japan and Novi, Mich. The magnetically permeable member  86  may include the Finemet® material having a manufacturer number MS-FR code FIAH0535. Generally, each magnetically permeable member  86  may be formed of a plurality of layers of the Finemet® nanoparticle crystalline material laminated together and held together with a selected adhesive. It is understood that magnetic permeable materials may include appropriate or selected materials such as Finemet® nanoparticle crystalline material, METGLAS® magnetic permeable materials Magnetic 2605SA1 or 2605HB1M Alloy sold by MetGlas, Inc. a division of Hitachi Metals America, Ltd. 
     The magnetically permeable members  82  may have a selected dimension including a length on the sides  274  and  276 . For example, the dimension of the side  274  may be about 100 mm to about 200 mm, further including about 156 mm to about 157 millimeters, and further including about 156.50 mm. The side  276  may include a length of about 70 mm to about 190 mm, further including a length of about 132 mm to about 133 mm and further including a dimension of about 132.2 mm. As discussed above, each of the magnetically permeable members  82   a ,  82   b ,  82   c , and  82   d  may have substantially identical dimensions. 
     The magnetically permeable members  82  may be formed as a plurality of layers of the Finemet® magnetically permeable material laminated to one another. The number of laminated layers may be about 8 layers to about 20 layers, including about 11 layers to about 13 layers, and further including about 12 layers. In various embodiments, the number of layers may further include about 15 layers. The layers may be laminated together with a selected piece of material including a substantially electrically and magnetically inert adhesive material. The magnetically permeable members  82 , as illustrated in  FIG.  5 C , may further include a thickness  280  of about 0.1 mm to about 0.2 mm, and further including a thickness  280  of about 0.12 mm. 
     With reference to  FIG.  6   , a schematic illustration of magnetic field lines from two coils, for example, coil  34   a  and  34   b  are illustrated. The coil  34   a  is schematically illustrated to produce the solid field lines  300  and the coil  34   b  includes the dashed field lines  320 . The coils  34   a  and  34   b  are illustrated in position above or near the field shaping assembly  80  and in the structural component  110 . The field shaping assembly  80  includes the components discussed above including the individual magnetically permeable members, such as the magnetically permeable member  82   a  and the conductive member  90  separated by the spacer member  86 . As illustrated in  FIG.  6   , the coil group  34  is positioned near the magnetically permeable member  82   a  and the coil group  36  is positioned near the magnetically permeable member  82   b . Further, the magnetically permeable members are separated by a space  330 . As illustrated in  FIG.  6   , therefore, the field line  300 ,  320  may interact with both the magnetically permeable member  82   a  and the electrically conductive member  90 . This allows for a selected diversity of vectors (e.g. different angles between two vectors at a single location in space) defined by the field lines  300 ,  320 , also referred to as field line vectors or field vectors. A diverse field may include a field that has vectors that are about 50 degrees to about 130 degrees relative to one another, including about 54 degrees to about 125 degrees apart, and further including about 54.7 degrees and about 125.3 degrees apart. 
     In various embodiments, a single point or location in space  340  may be defined by two vectors, a first vector  344  that relates to a field line  300   a  that is produced by the coil  34   a  and a second vector  346  that is defined by a field line  320   a  produced by the coil  34   b . The two vectors  344 ,  346  have an angle  348  between them. This angle may be equal to or greater than 0 degrees to less than or equal to 180 degrees. The two vectors  344 ,  346  are linearly dependent if the angle is equal to 0 degrees or 180 degrees. The two vectors  344 ,  346  are linearly independent if the angle is greater than 0 degrees to less than 180 degrees. The two vectors  344 ,  346  are orthogonal if the angle is equal to 90 degrees. The angle  348  between the vectors  344 ,  346  may be used in the calculation of the location  340  in a three-dimensional space. The calculation of a position of the point  340  in a three-dimensional space may be similar to that as understood by one skilled in the art and may be based upon a previously determined representation, such as a look-up table, determined and stored based on calibrated field measurements at a plurality of locations in the navigation space, such as defined by the field lines  300 ,  320 . 
     The angle  348  between the two vectors  344 ,  346  relative to the lines  300  and  320  may be different than an angle  360  between two vectors  362  defined by a field line  300   b  and a vector  364  defined by a field line  320   b . The different angle  360  between the two vectors  362 ,  364  may allow for different information regarding a location  370  at the origin of the two vectors  362 ,  364 . Additionally, as illustrated in  FIG.  6   , the field lines  300 ,  320  allow for a great diversity of measurable vectors at different locations relative to the coils  34   a  and  34   b  in the navigation space  41 . With additional reference to  FIG.  7   , fields may be considered diverse and/or have a selected diversity if, over a set of different locations, a majority of field vector pairs at those different locations are orthogonal or near orthogonal. As an example thereof and/or alternative example, fields may be considered diverse if a majority, including a selected number, of field vector pairs have angles equal to or greater than a selected angle of approximately 54.7° to less than or equal to 180° minus the selected angle or approximately 125.3°. As another example, fields may be considered diverse if a majority of field vector pairs have angles equal to or greater than approximately 50° to less than or equal to about 130°. Without being bound by the theory, but noting the angle range of these examples center around orthogonality at about 90°. Also, diverse fields may provide accurate, precise, and reliable navigation. Fields may be considered not diverse if, over a set of different locations, a majority of field vector pairs at those different locations are linearly dependent or nearly linearly dependent. As an example, fields may be considered not diverse if a majority of field vector pairs have angles equal to or greater than approximately 0° to less than or equal approximately 50° or equal to or greater than approximately 130° to less than or equal approximately 180°. 
     In various embodiments, the field lines  300 ,  320  may be substantially diverse and generally extend away from the field shaping assembly  80 , such as in the direction of arrow  380 . Therefore, the field lines  300 ,  320  that, along with field lines and fields produced by all of the coils in the TCA  30 , may define the navigation space or the navigable volume. Therefore, the navigable space may generally be away from the field shaping assembly  80 . The field shaping assembly  80 , thus also allows any magnetic field interfering objects positioned generally away from the TCA  30 , such as on a side opposite the field shaping assembly  80  from the TCA  30 , to not substantially affect the navigable space generated in the direction of arrow  380 . 
     The TCA  30  generally may be operated to transmit in a power range of about 1.0 nano-Watts (nW) to about 1.0 milli-Watts (mW), including about less than 0.1 mW. It is understood, however, that the TCA  30  may be operated to transmit at any appropriate selected power. 
     With continued reference to  FIG.  6    and further reference to  FIG.  7   , a graphical representation of possible field diversities is illustrated in  FIG.  7   . The y-axis represents a percentage of sensed field vectors pair angles over a set of locations and the x-axis represents an angles between two vectors that are determined. The diversity is the difference between two vectors having the same original in space, where the vectors are defined by the field lines of the field generated by the TCA  30 . 
     As illustrated in  FIG.  7   , if a plurality of transmit coils, such as conductive transmit coils, such as the coils discussed above, are laid substantially flat on a plane without any field shaping the percentage of vectors measured at specific angles is illustrated by the graphical area  390 . As illustrated, there is substantially no angular diversity as nearly all vectors have near 0° angular difference or near 180° angular difference. This is understood by one skilled in the art that the field lines are produced substantially in one direction relative to the flat coil array and do not generate a high degree of diversity between field lines. For a coil array positioned in an orthogonal configuration with co-center positioned and orthogonally oriented coil trios, such as a coil array in the AxiEM™ electro-magnetic navigation system, a diversity is illustrated by the graphical area  392  and includes a greater diversity of angle differences between measured field lines from the configured coils. Finally, in various embodiments, the localizer  20 , including the TCA  30  and the field shaping assembly  80 , has a diversity illustrated by graphical representation  394  as having a large diversity. In other words, the curve of measured angle differences between two vectors at different points is orthogonal or near orthogonal and spread out and not inclusive of only a few angle differences. For example, angles between vectors measured based upon field lines produced by the localizer  20  may have an angle difference between them over a larger broad range, such as about 50 degrees to about 130 degrees between vectors measured at different points. The greater diversity of angles between vectors measured at different points provides additional or greater information for navigation of a tracking device used to measure the fields produced by the coil array  30 . 
     The localizer  20 , including the field shaping components  80 , is configured to generate the diversity of field lines or angles between vectors defined by field lines as discussed above. In particular, the magnetically permeable members  82  may absorb and redirect a portion of the magnetic field. For example, each layer of the magnetically permeable members  82  may absorb and redirect a certain amount of the field before becoming saturated. Generally the magnetically permeable member  82  is able to absorb and redirect substantially all of the magnetic field that comes in contact with it, but some of the field is from the coil  34   a  and coil group  34 , may leak over and effect the conductive member  90 . However, as noted above, each of the coil groups  34 ,  36 ,  38 , and  40  includes an individual magnetically permeable portion having a space  333  therebetween. Therefore, at least a portion of the field produced by the coil groups  34 ,  36 ,  38 , and  40  may interact with the conductive member  90 . When a magnetic field interacts with conductive member  90  eddy currents may be generated. In various embodiments, an eddy current may form around the magnetically permeable member  82  on the conductive member  90 . 
     The eddy currents may then also produce electro-magnetic fields that are generally generated and formed in the navigation space. The induced magnetic field produced by the conductive member  90  may be proportional to the time derivative of the field produced by the TCA  30 . The induced field produced by the eddy currents in the conductive member  90  may generally be, in terms of complex function of time as is understood by one skilled in the art, out of phase and about 90° out of phase from those produced with the TCA  30 . As such, the induced field is diverse (e.g. orthogonal or near orthogonal) to the field produced with the TCA  30 . The field produced by the conductive member  90  due to the eddy currents may also be incorporated into navigation space and used by the navigation system  76  to determine location of the tracked member and tracking device, as discussed above. 
     With reference to  FIG.  8   , a flowchart  395  is illustrated. The flowchart  395  may be incorporated in an algorithm that includes instructions that may be stored on a storage or memory system, such as a memory system of the navigation system  10 , as discussed further herein. The instructions may be executed by the navigation processor  76  or other appropriate processor. The flowchart  395  may allow for determining or navigating based upon the fields formed by the TCA  30  and fields generated due to the eddy currents in the conductive member  90 . 
     In the flowchart  395 , in a first block  395   a  a drive current is used to generate a magnetic field as a complex function of time by driving current into the coils of the TCA  30 . Each of the coils of the TCA  30  may be driven in various multiplexing manners to allow distinguishing between each field generated by each coil. Multiplexing may include frequency multiplexing, time multiplexing, code multiplexing, and/or combinations of multiplexing. After driving current to generate the field with the TCA  30 , a tracking device, such as the tracking device  52  of the instrument  50  may sense the total magnetic field as a complex function of time in block  395   b.    
     The sensed total magnetic field may then be transferred to a processor system, for example the navigation processor  76 , as discussed above, which may include or access instructions to separate real and imaginary field components sensed by the tracking device in block  395   b . It is understood that any appropriate processor system or processor specifically designed or a general purpose processor executing code may be used for separation of the real and imaginary components of the magnetic field. The separation of real and imaginary magnetic field components in block  395   c  may be based upon generally known computations, as is generally understood by one skilled in the art. The separation of the real and imaginary magnetic field components, however, allows for the sensed total magnetic field to be analyzed in further detail to allow for a greater accuracy of tracking the tracking device  52 . Further, by accounting for the real and imaginary magnetic field components, the field generated due to the eddy currents in the conductive member  90  may be used to provide additional field diversity and tracking information for navigation of the instrument  50 . 
     Accordingly, navigation of the instrument  50  by sensing the field with the tracking device  52  may allow for navigation over the real and imaginary magnetic field components in block  395   d . As discussed above, and further herein, the navigation system  10  may be used to navigate the location of the instrument  50  by sensing the field generated by the localizer  20  which may include fields generated by the TCA  30  and fields generated due to eddy currents in the conductive member  90 . Moreover, the eddy currents generated in the conductive member  90  may be based upon the shape, size, and location of the magnetically permeable members  82  relative to the conductive member  90 . Accordingly, as discussed above, the shape and position of the coils of the TCA  30  and of the field shaping components  80  may generate a field that allows for navigation of the instrument  50 . 
     With reference to  FIG.  9   , the localizer  20  may be used in the navigation system  10 , as discussed above. The localizer  20  may be positioned relative to a subject, such as a patient  400 , while a user  402  operates or moves the instrument  50  having the tracking device  52  associated therewith. The DRF  54  may be connected to the subject  400 . The subject  400  may be positioned near or adjacent the localizer  20 . The localizer  20  may be held and supported on a support  384 , such as an operating room table. The navigation system  10  may also include a second localizer, such as an optical localizer  420 . 
     Tracking information, including magnetic fields sensed with the tracking devices  52 ,  54  may be delivered via a communication system, such as a coil array and tracking device controller  430  to the navigation processor  76 . Navigation processor  76  may be a part of a work station or computer system  434  that includes a display  436  to display an image  440 . Further, a tracked location of the instrument  50  may be illustrated as an icon  442  relative to the image  440 . Various other memory and processing systems may also be provided such as a memory system  446  in communication with the navigation processor  76  and an imaging processing unit  448 . The image processing unit  448  may be incorporated into imaging system  450 , such as the O-arm® imaging system, as discussed above. The imaging system  450  may be a x-ray imaging system including a x-ray source  452  and a detector  454  that are moveable within a gantry  460 . The imaging system  450  may also be tracked with a tracking device  464 . 
     Information from all of the tracking devices may be communicated to the navigation processors  76  for determining a location of the tracked portions relative to each other and/or for localizing the instrument  50  relative to the image  440 . The imaging system  450  may be used to acquire image data to generate or produce the image  440  of the subject  400 . It is understood, however, that other appropriate imaging systems may also be used. The coil array controller  430  may be used to operate and power the TCA  30  and the localizer  20 , as discussed above. 
     The localizer  20 , as discussed above, may include a various components including the TCA  30  that includes one or more coils positioned relative to one another and other components, such as the field shaping assembly  80 . As discussed above, the field shaping assembly  80  may be positioned within a holding structure and include various other portions such as one or more cover portions  100 ,  104  and holding portions such as the structural or holding component  110 . As illustrated above, the localizer  20  includes the TCA  30  positioned on the structural component or positioner  110  relative to the field shaping assembly  80 . The field shaping assembly  80 , as discussed above and illustrated in  FIG.  1   , includes a plurality of or portions such as the magnetic permeable member  82  positioned relative to a coil group, such as the coil group  34 . A plurality of the magnetic permeable members  82  are positioned spaced apart from one another relative to the single conductive member  90 . Accordingly the localizer  20  may include a plurality of coil groups in the TCA  30  that are positioned relative to a plurality of the magnetically permeable members  82  all positioned relative to the single or one conductive member  90 . It is understood, according to various embodiments, that the localizer  20  may include different configurations including the coil groups in the TCA  30 , the magnetic permeable members or single member  82 , and the conductive member  90 . 
     According to various embodiments, with reference to  FIG.  10 A  and  FIG.  10 B , the localizer  20 , or other appropriate localizer, including those discussed further herein may include components or portions similar to the localizer  20  illustrated in  FIG.  1   . According to various embodiments, however, the localizer may include different shapes and/or configurations of the TCA  30 , and/or the field shaping assembly  80 . For example, the field shaping assembly  80  may include a coil or coil group that may include one or more coils, such as a coil  534 . It is understood, that the discussion here of the coil  534  may refer to a plurality of coils, such as a plurality of coils in the coil groups, such as the coil group  34 , discussed above. Accordingly, the discussion of the coil  534  as a single coil is merely exemplary and the coil  534  and the related assembly may be repeated and selectively shaped, similar to the coils of the coil groups discussed above, to generate a selectively shaped (e.g. diverse) field that includes a selected or appropriate diversity, such as that discussed above. 
     With continuing reference to  FIGS.  10 A and  10 B , the coil  534  may be positioned within a cup or well field shaping assembly  580 . The field shaping assembly  580  may include a conductive member  590  and one or more spacer member portions  586 , as discussed above. It is understood that the spacer  586 , however, may be optional and is not necessary between the conductive member  590  and a well or cup magnetic permeable member or layer  582 . The conductive member  590  may be formed of materials, including those discussed above. Further, the magnetic permeable member  582  may also be formed of the similar materials as discussed above. THE cupped shape magnetic permeable member may be provided to shape and direct the transmitted field form the coil  534 , such as away from the coil  534 , but within the outer wall  600 . 
     The cupped magnetic permeable member  582  may include various portions or assemblies, such as a wall or upturned sidewall  600 . The upturned sidewall may extend from a bottom wall  602  over which the coil  534  is positioned. The sidewall  600  may be positioned or formed to surround the coil  534 . In addition to the sidewall  600  and the bottom wall  602 , a punt or central wall or extension  604  may also extend from the bottom wall  602  up to and/or through the coil  534 . As specifically illustrated in  FIG.  10 A , the punt wall  604  extends through the coil  534 . It may be possible that the punt wall  604  acts as a core for the coil  534 . It is understood, however, that the punt wall portion  604  may only extend a portion through or into the coil  534  as illustrated in Fanta  604 ′. 
     The magnetic permeable member  582  may interact with a field transmitted or generated by the coil  534  in a manner similar to that discussed above. Given the shape and/or position of the magnetic permeable member  582  the field or field lines formed by the coil  534  may be positioned or shaped relative to the conductive member  590 . 
     In addition, the coil  534  may be positioned substantially perpendicular to the conductive member  590 . In other words, a central axis  534   a  or axis around which the coil  534  is wound, may be formed at an angle or positioned at an angle  5340  relative to a surface of the conductive member  590 . In various embodiments, the axis  534   a  may be substantially perpendicular such as the angle  5340  is 90 degrees or may be a non-90 degree angle. For example, the angle  5340  may be about 40 degrees to about 150 degrees. As discussed above, positioning the coil  534  within the magnetic permeable member  582  may position or move the field formed by the coil  534  relative to the conductive member. It is further understood that the coil  534  and the magnetic permeable member  582  may be formed as a unit such that the punt wall  604  may be positioned along the axis  534   a  and may also be moved at the selected angle or position of the selected angle  5340  relative to the conductive member  590 . 
     With continuing reference to  FIG.  10 A  and additional reference to  FIGS.  10 C and  10 D  the cupped or well-shaped magnetic permeable member  582  may be selectively sized and/or shaped relative to the coil  534 . As illustrated in  FIG.  10 C , the magnetic permeable cup  582  includes a cup  582 ′ that includes a side wall  600 ′ that has a height  601 ′ from a bottom surface or plane, such as the bottom wall  602 ′. The height  601 ′ may also be relative to a surface of the conductive member  590  and from the bottom wall  602 ′ is merely exemplary. However, the height  601 ′ may be less than a height  601  of the magnetic permeable  582 , illustrated in  FIG.  10 A . Further, the magnetic permeable member  582 ′, according to various embodiments, does not and need not include the punt wall  604 . It is further understood that the spacer  586 , according to various embodiments, may include an air gap or space between the magnetic permeable member  582 ′ or magnetic permeable member  582  or  82 , and the respective conductive member. 
     The coil  534  may be positioned relative to the magnetic permeable member  582 ′ in any appropriate manner, such as with a spacer  605  which may be formed of a substantially inert material (e.g. non-conductive and/or non-magnetically interfering or distorting such as non-conductive cloth or other textile material or polymer material). The coil  534 , therefore, may be positioned relative to the magnetic permeable member  582 ′ to form a field relative to the conductive member  590 , as discussed above. The shape and position of the magnetic permeable member  582 ′, however, may influence or shape a field formed or transmitted by the coil  534 . Again, the spacer  586  may be selected with the position between the magnetic permeable member  582 ′ and the conductive member  590  or may be selectively not positioned. Further, the transmitted field from the coil  534  may induce a current in the conductive member  590  which then generates an induced field, as discussed above. The induced field may be diverse or have diverse components relative to the transmitted field. Shaping and/or angling the magnetic permeable member  582 ′ relative to the conductive member  590  may further create the diverse field. 
     With continuing reference to  FIG.  10 A  and additional reference to  10 D, a magnetic permeable member  582 ″ is illustrated. The magnetic permeable member  582 ″ includes a sidewall  602 ″ that has a height  601 ″ relative to a bottom wall  602 ″. Again the height  601 ″ may be different, such as less than, the height  601 ′ and/or the height  601 . In various embodiments, the height  601 ″ may be such that the sidewall  602 ″ includes an upper or terminal surface or edge  603  that is below a portion, such as any portion, including at least a top portion, of the coil  534 . Accordingly, it is understood that the magnetic permeable member  582  may be shaped relative to the coil  534 , or any appropriate coil for forming or shaping the localizer  20  to shape a selected field. 
     In addition to, or alternatively to the above described embodiments of the TCA  30  and the various coils and coil groups thereof, the localizer  20  may include embodiments as discussed and illustrated herein. It is understood that while an exemplary coil or coil group may be discussed, a plurality of each may be included in a single localizer, such as the localizer  20  discussed above. 
     Turning reference to  FIG.  11 A ,  FIG.  11 B , and  FIG.  11 C  field shaping components, according to various embodiments, are illustrated. The field shaping components may include a substantially circular geometry, including a field shaping component or assembly  680  as illustrated in  FIG.  11 A . As illustrated in  FIG.  11 B  a field shaping component or assembly  780  may include an elongated or oval shape, as discussed further herein. Further, as illustrated in  FIG.  11 C  a field shaping component or assembly  880  that may include various shapes, such as a rounded triangle, rounded corner triangle, or other complex shapes. Accordingly, the field shaping component or assembly, such as the circular field shaping component  680 , the oval field shaping component  780 , or the complex shape field shaping component  880  may be included with the localizer  20 , or any appropriate localizer. As discussed above, each field shaping component or assembly may have a coil positioned relative thereto. 
     With additional reference to  FIG.  11 A , the field shaping component  680  may have positioned relative thereto a coil such as a coil  634 . The coil  634  may be positioned at a center  690  of the field shaping component  680 . It is understood, however, that a central axis (e.g. an axis around which the coil  634  is wound) may be positioned off center or away from the center  690  of the field shaping component. Nevertheless the field shaping component  680  may include a magnetic permeable member or portion  682  that has a radius  682   r . The field shaping component  680  may also include additional portions or members, such as those discussed above, including a conductive layer portion  690 . As discussed above one or more spacer portions may be positioned between the magnetic permeable member  682  and the conductive member  690 . The field shaping component  680 , according to various embodiments including those also as discussed above, may further include a second or auxiliary magnetic permeable member or portion  696 . Accordingly, the field shaping component  680  may include the conductive member  690  positioned between the first magnetic permeable member  682  and the second magnetic permeable member  696 . Thus, the first magnetic permeable member  682  and the second magnetic permeable member  696  are on opposite or opposed sides of the conductive member  690 . It is understood, that various shapes of field shaping components may also include this construction or arrangement. 
     In various embodiments, the magnetic permeable member positioned on a side of a conductive member away from a coil transmitting a field may assist in absorbing additional field from the coil that would extend beyond the conductive member. For example, the second magnetic permeable member  696  may absorb field form the coil  634  that extends beyond the conductive member  690 . Therefore, an interfering object or object on a side of the conductive member away from the coil  634  is less likely or will not influence or have induced therein a current. It is understood, the second or auxiliary magnetic permeable member of the field shaping assembly according to various embodiments may produce the same or similar effect. 
     Further each of the members or components may be positioned relative to one another. For example, the conductive member  690  may include an area or region  690   a  that extends beyond an outer edge of the first magnetic permeable member  682  and the second magnetic permeable member  696  includes an area or region  696   a  that extends beyond an edge of the conductive member  690 . It is understood that the second magnetic permeable member  696  may be selected to be optional and need not be required or included in the field shaping component  680 . Further, according to various embodiments, a second magnetic permeable member may be included in any appropriate field shaping component assembly, including the field shaping assembly  80  (as illustrated in  FIG.  1   ) and/or other field shaping assemblies including the field shaping assembly  580  discussed above. 
     Turning reference to  FIG.  11 B , the field shaping component  780  may include a first magnetic permeable member  782  positioned over or relative to a conductive member or component  790  and a second magnetic permeable member  796 . As discussed above each of the respective members, such as the conductive member  790  and the second magnetic permeable member  796  may have an edge that extends beyond an edge of the member or portion above it. Accordingly the field shaping assembly  780  may again include the first magnetic permeable member  782  and the second magnetic permeable member  796  with the conductive member  790  therebetween. It is further understood, however, that the second magnetic permeable member  796  may be optional. 
     The field shaping component  780  may include or have positioned relative thereto a coil  734 . A center of the coil  734   c  may be positioned or offset from a center or point  782   c  of the first magnetic permeable member  782 . The shape of the first magnetic permeable member  782  may include a first distance or radius  782   r ′ and a second distance or radius  782   r ″. The two radii  782   r ′,  782   r ″ may be different to provide or give a selected shape to the magnetic permeable member  782 . Further the coil  734  may be positioned that a center or central axis  784   c  may be positioned at the point  782   c . Positioning the coil  734  relative to or at a different location on the magnetic permeable member  782  may be selected to achieve a selected shape of a field formed by the coil  734 , as discussed above, to include or create a selected field diversity. 
     Turning reference to  FIG.  11 C , the field shaping assembly  880  may include a first magnetic permeable member  882 , a conductive member  890 , and a second magnetic permeable member  896 . Again, the second magnetic permeable member  896  may be optional, but if selected the conductive member  890  may be positioned between the first magnetic permeable member  882  and the second magnetic permeable member  896 . The shape of the first magnetic permeable member  882  may be a selected shape such as a complex shape including a generally triangular portion  882   t  and a rectangular portion  882   r . The first magnetic permeable member  882  may be formed as a single piece but including the selected shape as illustrated in  FIG.  11 C . It is understood, however, as discussed further herein, that the field shaping assembly may have an appropriate shape to achieve a selected diversity. Accordingly, a coil  834  may be positioned such that a center or central axis  834   c  is positioned in one of the regions of the magnetic permeable member  882 , such as in the triangular  882   t . Further, the connective member  890  may extend beyond an external edge or parameter of the first magnetic permeable member  882  and the second permeable member  896  may extend beyond a parameter of the connective member  890 . 
     As illustrated in  FIG.  11 A ,  FIG.  11 B , and  FIG.  11 C  the respective coils  634 ,  734 ,  834  include substantially round perimeters or cylindrical shapes. Accordingly distance from the respective centers to the outer perimeters of the respective coil  634 ,  734 ,  834  may be substantially uniform around the outer perimeters of the coil. It is understood, however, that the coils may include non-circular or cylindrical shapes, including oval or asymmetrical shapes, as discussed above. Further, as also illustrated in  FIGS.  11 B and  11 C  and as exemplary described and discussed relative to  FIG.  11 A  the respective coils may be positioned at asymmetrical or non-central locations of the respective field shaping assemblies. 
     With reference to  FIG.  11 A ,  FIG.  11 B , and  FIG.  11 C  a field shaping component may include a single coil positioned relative thereto. In various embodiments, however, a plurality of coils may be positioned relative to the respective field shaping assemblies. Also, the plurality of coils may be placed asymmetrically, such as not equidistant apart or from edges, of the respective field shaping assemblies. 
     As illustrated in  FIG.  12 A  selected field shaping assemblies may include a plurality of coil positioned relative thereto, as discussed above as illustrated in  FIG.  1   . With additional reference to  FIG.  12 A  a field shaping assembly  980  is illustrated. The field shaping assembly  980  may include a first magnetic permeable member  982  and a conductive member  980 . Again, the field shaping assembly  980  may include an optional second magnetic permeable member  996  wherein the conductive member  990  is positioned between the first magnetic permeable member  982  and the second magnetic permeable member  996 . The field shaping assembly  980  may have a selected shape, such as a substantially triangular shape. Further a coil group may include a first coil  934   a , a second coil  934   b , and the third coil  934   c . Each of the coils  934   a ,  934   b , and  934   c  may be positioned away from a center and/or near a corner of the triangle. Each of the coils  934   a ,  934   b ,  934   c  may have a respective center and may be substantially round or cylindrical shaped. The coils, however, may generate a field that is substantially diverse due to the field shaping assembly  980 , as discussed above. 
     Turning reference to  FIG.  12 B  a field shaping assembly  1080  is illustrated. The field shaping assembly  1080  may be substantially rectangular and include a first magnetic permeable member  1082  and a conductive member  1090 . Again an optional second magnetic permeable member  1096  may be positioned such that the conductive member  1090  is between the first magnetic permeable member  1082  and the second magnetic permeable member  1096 . As discussed above each of the respective members  1090  and second permeable member  1096  may have an outer parameter that extends a selected distance or area beyond the adjacent or next layer. Further, selected spacers may be positioned between each of the respective layers  1082 ,  1090 ,  1096  as discussed above. 
     Positioned relative to the first magnetic permeable member  1082  may be a coil group including a first coil  1034   a ,  1034   b , and  1034   c . Each of the coils may be elongated or ellipsis or oval in shape rather than round. Accordingly, each of the coils  1034   a ,  1034   b , and  1034   c  may generate or transmit a field relative to the field shaping assembly  1080  that is different than a field generated by a cylindrical or round coil. Again the respective shape of the coils and the field shaping assembly  1080  may affect or generate a selectively diverse field as discussed above. 
     As discussed and illustrated in  FIG.  11 A ,  FIG.  11 B ,  FIG.  11 C ,  FIG.  12 A ,  FIG.  12 B , and in various embodiments as discussed above, different portions of the field shaping assemblies may be substantially independent of other field shaping assembly portions. In various embodiments, as illustrated in  FIG.  1   , a plurality of coil groups may be positioned relative to a plurality of separated magnetic permeable members  82  that are all positioned on a single or unitary conductive member  90  of the field shaping assembly  80 . It is understood that alternative embodiments and/or additional embodiments may be used either alone or in combination with the field shaping assembly  80  or as otherwise understood by one skilled in the art. 
     Turning reference to  FIG.  13   , a field shaping assembly  1180  is illustrated. The field shaping assembly  1180  includes various portions such as a first magnetic permeable member  1182 , a conductive member  1190 , and a second magnetic permeable member  1196 . The first magnetic permeable member  1182  may be provided as one or more members that are formed as substantially single units or members that are spaced apart from one another, such as a first spacing  1200  and a second spacing  1204 , but positioned over or on the connective member  1190 . Accordingly, as illustrated in  FIG.  13    the conductive member  1190  may have an external edge  1206  that extends beyond an external edge of any one of the member  1182 , which may include four magnetic permeable members  1182   a ,  1182   b ,  1182   c , or  1182   d . The conductive member  1190  may be provided or formed as a single piece. As a single piece the conductive member  1190  is conductive throughout its area. 
     The first magnetic permeable members  1182  positioned on or over the conductive member  1190  may be similar to the embodiment illustrated in  FIG.  1   . It is understood, however, that various spacers may also be positioned between the magnetic permeable members  1182  and the conductive member  1190 . As illustrated in  FIG.  13   , however, an alternative second magnetic permeable member  1196  may be positioned on an opposite side of the conductive member  1190  from the first magnetic permeable members  1182 . An external or outer parameter  1210  of the second magnetic permeable member  1196  may extend beyond the outer parameter  1206  of the conductive member  1190 . It is understood, however, that the second magnetic permeable member  1196  may be provided as a single member that extends as a single member or formed as a single member within the parameter  1210  of the magnetic permeable member  1196 . 
     It is further understood, however, that a second magnetic permeable member  1196  may be optional and is not required. Further it is understood that the first magnetic permeable members  1182  may be provided in any appropriate number and four is merely exemplary. Further the field shaping assembly  1180  may be provided as a portion of the localizer  20 , as discussed above, including the TCA  30  and/or a TCA  1130  as illustrated in  FIG.  13   . The TCA  1130  may include a plurality of coil groups such as a first coil group  1134 , a second coil group  1136 , a third coil group  1138 , and a fourth coil group  1140 . Each of the coil groups may include a selected number of coils, such as three coils illustrated in  FIG.  13   , including the three coils  1134   a ,  1134   b , and  1134   c  of the first coil group  1134 ; a first coil  1136   a , a second coil  1136   b , and a third coil  1136   c  of the second coil group  1136 ; a first coil  1138   a , a second coil  1138   b , and a third coil  1138   c  of the third coil group  1138 ; and a first coil  1140   a , a second coil  1140   b , and a third coil  1140   c  of the fourth coil group  1140 . If less than four of the magnetic permeable members  1182  are provided, less coil groups may also be provided. Nevertheless, each of the coils of the respective coil groups  1134 - 1140  may generate a field relative to the field shaping assembly  1180 . 
     The field shaping assembly  1180 , however, in combination with the TCA  1130  may generate the selectively diverse field as discussed above. The field shaping assembly  1180  may include various features such as shapes of the first conductive member  1182 , including those discussed above, or any appropriate shape. Further, the field diversity may be achieved by positioning the coils of the TCA  1130  relative to the first magnetic permeable members  1182  in a selected or appropriate manner to achieve the selected diversity. For example, asymmetrically placing the coils relative to the first magnetic permeable members  1182  may achieve the appropriate or selected diversity of the field. Also, as discussed above, a portion of the transmitted field that extends beyond the first magnetic permeable members  1182  may induce a current in the conductive member  1190 , which, in turn, will generate an induced field. 
     Accordingly, although rectangular members are illustrated in  FIG.  13   , it is understood that the first conductive members  1182  may be circular, trapezoidal, or other appropriate shape even if placed on the conductive member  1190  that is substantially rectangular. Moreover, the conductive member  1190  may be provided as individual separated members such as the conductive member  1190  not being provided as a single unitary member, but as at least two members that are positioned between the first magnetic permeable members  1182  and the first magnetic permeable members  1196  with the one or more conductive members  1190  therebetween. It is further understood, however, that the second magnetic permeable member  1196  is optional and therefore two or more conductive members  1190  may be positioned relative to the first magnetic permeable members  1182  to form the field shaping assembly  1180  with the TCA  1130 . 
     Further the selected coils of the coil groups  1134 - 1140  of the TCA  1130  may be selectively shaped, such as oval, round, cylindrical, or other appropriate shape relative to selected field shaping members of the field shaping assembly  1180 . It is further understood that the TCA  1130  may include the connections and controls, as discussed above, for driving and otherwise operating a localizer  20 . The coils of the TCA  1130  are shown relative to the field shaping assembly  1180  as merely exemplary and being shown without the other portions of the localizer assembly. 
     Accordingly, as discussed above, the TCA according to various embodiments, including those discussed above in combination and/or alternatively to one another, may be used to generate a field. A field shaping assembly, also according to various embodiments including those discussed above as alternatives or in addition to one another, may be used to shape the field selectively. The shaped field achieves a selected diversity, as also discussed above, to allow for tracking of a selected sensor within a navigation domain or volume. The diversity provides for or allows for a plurality of vectors that are orthogonal or substantially orthogonal to one another to assist in increased accuracy and/or speed in determining a location of the tracking device. In various embodiments, a transmitted field may be or is diverse relative to an induced field (i.e. generated from an induced current in a conductive member). Accordingly, the tracking coil or other sensor that has been tracking space with the navigation domain may be resolved substantially precisely or accurately in three-dimensional space including an X,Y,Z position and orientation, including at least one of yaw, pitch, or roll. 
     The field shaping assembly, such as the field shaping assembly  80 , or according to any appropriate embodiment including those discussed above, may include the magnetic permeable members of the materials discussed above and the conductive member of the materials discussed above. Accordingly, various embodiments are discussed that may be combined or provided as alternatives to one another. Nevertheless, the field shaping assemblies, as discussed herein, may operate to substantially reduce or eliminate distortion or interference that may be introduced by a conductive member other than the field shaping assembly. Therefore, tracking of the tracking device in the navigational domain may be substantially immune to various members or materials that may affect the field produced by the TCA. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.