Navigation system and method

Abstract

A localizer system is disclosed. The localizer system can be incorporated into a navigation system for tracking a tracking device. Generally, the localizer can include an array of transmit coils and a field shaping assembly.

Description

[0001] This invention patent application is a divisional application of the invention patent application with international application number PCT / US2019 / 046343, international application date of August 13, 2019, and Chinese national phase application number 201980060026.6, entitled "Guided Extension Catheter Assembly, System and Method of Use".

[0002] field

[0003] This disclosure generally relates to systems for generating magnetic fields, and more particularly to systems and arrangements for generating selected electromagnetic fields. background

[0004] This section provides background information related to the present invention, but is not necessarily prior art.

[0005] In navigation systems used in various procedures such as surgical procedures and assembly procedures, instruments or objects can be tracked by measuring the effect of a magnetic field on a sensor coil. The sensor coil may comprise a conductive material placed within a magnetic field, inducing a current in the coil within the magnetic field. The measured induced current can be used to identify or determine the position of the instrument or object. However, improvements to the coil's position determination are desired in various aspects.

[0006] One or more electromagnetic fields can be generated by multiple purposefully positioned and oriented transmitting coils. Various transmitters or field generation systems include the AxiEM™ electromagnetic navigation system, sold by Medtronic Navigation, Inc., which has a business location in Louisville, Colorado. The AxiEM™ electromagnetic navigation system may include multiple transmitting coils for generating one or more electromagnetic fields, which are sensed by a tracking device, which may be sensor coils, to allow navigation systems, such as the StealthStation® surgical navigation system, to track and / or indicate the tracking position of instruments.

[0007] Transmitter coils, positioned and oriented around each other, typically fill a volume smaller than the navigation volume generated by the transmitter coils. However, the volume including the transmitter coils is usually positioned near the patient so that the navigation field or volume surrounds the area of ​​the patient in which navigation will take place. Therefore, the transmitter coil array can be located close to the individual performing the surgery, such as a surgeon.

[0008] Overview

[0009] This section provides a general overview of the invention, but is not a complete disclosure of its entire scope or all its features.

[0010] A positioner is disclosed that may include a transmitting component, specifically a transmitting coil array (TCA), and a field shaping assembly configured and operable to emit one or more diverse magnetic fields. Specifically, the positioner is configured to generate field vectors that are at different heights relative to each other, these field vectors having a distribution that is relatively orthogonal or nearly orthogonal to a measurable vector relative to the origin or within a volume. Even if the multiple coils of the TCA are positioned on a substantially flat plane, one or more field differences will still occur. The accuracy, precision, and reliability of determining the position of sensors such as coils can be improved using additional measurements, specifically additional measurements of the effects of one or more different magnetic fields on the sensor coils.

[0011] The locator can be formed from multiple cooperating features, including a transmitter / emitter coil array (TCA) and a field shaping assembly, the transmitter / emitter coil array comprising one or more transmitter coils. The field shaping assembly is provided to include multiple portions or components that interact with magnetic fields generated by the one or more coils, respectively. For example, the multiple coils can be formed as one or more trios or triplet coils, all of which are powered to generate a field. The field shaping segments can be provided to interact substantially independently of the field. Thus, the TCA can generate or form a generated navigation field within a navigable volume, which can substantially simulate the field created by concentrically positioned and orthogonally oriented coils. Therefore, the TCA can include a low-profile or flat configuration and be positioned close to or adjacent to the operating room without interfering with its location. For example, the TCA can be positioned below the patient or between the patient and a supporting structure.

[0012] Field shaping components may be included in or fixed relative to the TCA. The TCA and field shaping components may also be referred to as positioners. Field shaping components can be used to influence the generated field to create a second field configuration, ensuring field diversity. Field shaping components can also mitigate or eliminate the influence of external conductive surfaces and materials such as conductive metals, which may be present in the support structure or other structures remote from the positioner. For example, the TCA may be positioned on a surgical table that may include metal or other conductive materials, where the field shaping component ensures that the conductive materials do not affect or substantially do not affect the field generated by the positioner. In various embodiments, substantially influencing the field generated by the positioner may include locations near the positioner where conductive materials may be present, but without requiring compensation (e.g., processing or algorithmic compensation) to allow for proper and accurate tracking of the selected tracking device.

[0013] Other applicable fields will become apparent from the description provided herein. The descriptions and specific examples in this overview are intended for illustrative purposes and are not intended to limit the scope of the invention.

[0014] Attached Figure

[0015] The accompanying drawings described herein are for illustrative purposes only, and not for all possible implementations, and are not intended to limit the scope of the invention.

[0016] Figure 1 This is an exploded view of the locator;

[0017] Figure 2A This is a top view of the coils in the transmitting coil array;

[0018] Figure 2B yes Figure 2A The side view of the coil shown;

[0019] Figure 3 This is a top view of the positioner's structural components;

[0020] Figure 3A yes Figure 3 Detailed view at point A in the diagram;

[0021] Figure 3B It is along Figure 3 The sectional view taken from line 1-1 in the diagram;

[0022] Figure 4 It is along Figure 3 The sectional view taken from line 2-2 in the middle;

[0023] Figure 4A yes Figure 4 Detailed sectional view at point B;

[0024] Figure 5A This is a plan view of the field forming component;

[0025] Figure 5B This is a cross-sectional view of a conductive component;

[0026] Figure 5C This is a cross-sectional view of a magnetically permeable component;

[0027] Figure 6 This is a schematic diagram of a positioner that includes representative field lines;

[0028] Figure 7 This is an exemplary illustration of the difference in magnetic fields generated by the locator;

[0029] Figure 8 It is a flowchart including the steps used for navigation instruments;

[0030] Figure 9It is an environmental map of the navigation system;

[0031] Figure 10A Field forming components according to various embodiments are shown;

[0032] Figure 10B It is along Figure 10A The sectional view taken from line 3-3 in the diagram;

[0033] Figure 10C This is a cross-sectional view of the field forming assembly and coil according to various embodiments;

[0034] Figure 10D This is a cross-sectional view of the field forming assembly and coil according to various embodiments;

[0035] Figure 11A , Figure 11B and Figure 11C A field forming assembly with a single coil is shown according to various embodiments;

[0036] Figure 12A and Figure 12B Field shaping assemblies according to various embodiments are shown, these field shaping assemblies having a plurality of coils positioned relative to them; and

[0037] Figure 13 A field forming assembly according to various embodiments is shown, the field forming assembly including a plurality of coils positioned relative to it.

[0038] In the various views shown in the accompanying drawings, the corresponding reference numerals indicate the corresponding components.

[0039] Detailed Explanation

[0040] Exemplary embodiments will now be described more fully with reference to the accompanying drawings.

[0041] May include locator components or such as Figure 1 The navigation system 10 of the system 20 shown is... Figure 9 This can be used for various purposes or procedures. A navigation system can be used to determine or track the position of an instrument within a volume. Tracking the instrument's position assists the user in determining its location, even if the user does not directly see the instrument. Position may include at least one three-dimensional localization (e.g., X, Y, or Z coordinates) and at least one orientation (e.g., yaw, pitch, and roll). Therefore, in various embodiments, position may include six degrees of freedom. Various procedures, such as performing repairs or assembling inanimate systems like robotic systems, assembling parts of a fuselage or automobile, may obstruct the user's line of sight. Various other procedures may include surgical procedures, such as performing spinal procedures, neural procedures, locating deep brain simulation probes, or other surgical procedures on a living organism. In various embodiments, for example, the living organism may be a human subject, and the procedure may be performed on a human patient.

[0042] However, in various embodiments, as further discussed herein, the surgical navigation system 10 ( Figure 9 This can be combined with various components, such as those disclosed in U.S. Patent Nos. RE44,305, 7,697,972, 8,644,907, and 8,842,893; and U.S. Patent Application Publication No. 2004 / 0199072, all of which are incorporated herein by reference. The various components of the surgical navigation system may include imaging systems operable to image the patient, such as O-arm® imaging systems, magnetic resonance imaging (MRI) systems, computed tomography (CT) systems, etc. Images may be acquired during or before the surgical procedure for display on a display device. Figure 9 As shown, the instrument can be tracked in a trackable or navigable volume, which is generated by a transmitter or transmitter coil array incorporated into the locator 20.

[0043] Reference Figure 1 The locator 20 may be an electromagnetic (EM) locator operable to generate an electromagnetic field using a transmitting coil array 30. The coil array 30 may include one or more coil groups or arrays, such as a first group 34, a second group 36, a third group 38, and a fourth group 40. Each group may include three coils, also referred to as a tripartite or triplet. For example, the first group 34 may include a first coil 34a, a second coil 34b, and a third coil 34c. Similarly, the second group 36 may include a first coil 36a, a second coil 36b, and a third coil 36c. The third group 38 may include a first coil 38a, a second coil 38b, and a third coil 38c. The fourth group 40 may include a first coil 40a, a second coil 40b, and a third coil 40c. The coils can be powered to generate or form an electromagnetic field by driving current through the coils of coil groups 34, 36, 38, and 40. When current is driven through the coils, the generated electromagnetic field extends away from coils 34, 36, 38, and 40 and forms a navigation domain or volume 41 (e.g., as shown in the image). Figure 6 (As shown).

[0044] The navigation domain or volume roughly defines the navigation space or patient space. As is generally understood in the art, an instrument tracking device 52 can be used to track an object or instrument 50, such as a drill bit, lead wire, etc., within the navigation domain relative to the patient or subject. For example, the user can freely move the instrument 50 relative to a dynamic preference frame (DRF) or a reference frame tracker 54, which is fixed relative to the subject. Both tracking devices 52 and 54 may include sensing coils (e.g., sensors formed as coils of conductive material) that sense and are used to measure magnetic field strength, etc. Since the tracking device 52 is connected or associated with the instrument 50 relative to the DRF 54, the navigation system 10 can be used to determine the position of the instrument 50 relative to the DRF 54. The navigation volume or patient space can be registered to the patient's image space, and an icon representing the instrument 50 can be overlaid on the image. As is commonly known in the art, patient space-image space registration and position determination of tracking devices, such as tracking device 52 relative to DRF, such as DRF 54, can be performed, including those disclosed in U.S. Patent Nos. RE44,305, 7,697,972, 8,644,907, and 8,842,893; and U.S. Patent Application Publication No. 2004 / 0199072, all of which are incorporated herein by reference.

[0045] Continue to refer to Figure 1 The positioner 20 may also include a printed circuit board (PCB) 60, on which traces from a cable connector 62 to which a communication cable or power cable 64 can be connected. The traces on the PCB 60 connect the cable 64 to various cable connectors 66, 68, 70, and 72. Connectors may include leads or wires that can be connected to each coil in coil groups 34, 36, 38, and 40. Therefore, the coils in coil groups 34, 36, 38, and 40 can be powered or driven by the navigation processor system 76 through the traces on the PCB 60. The navigation processor system may include those in U.S. Patent Nos. RE44,305, 7,697,972, 8,644,907, and 8,842,893; and U.S. Patent Application Publication No. 2004 / 0199072, all of which are incorporated herein by reference, or may also include commercially available StealthStation® or Fusion™ surgical navigation systems sold by Medtronic Navigation, Inc., which has a business location in Louisville, Colorado.

[0046] Positioner 20 also includes field shaping assembly 80. Field shaping assembly 80 typically includes a first magnetically permeable portion 82, which is also substantially non-conductive, a spacer 86, which may be substantially inert, and a substantially conductive portion 90. The magnetically permeable portion 82 may include various properties, such as typically high permeability, substantially non-conductive, high magnetic saturation, and low coercivity, as discussed further herein. The spacer 86 is substantially inert with respect to current and magnetic fields and may include a polymer or plastic material such as polycarbonate having a thickness of about 0.001 mm to about 10 mm, including about 1.0 mm. The thickness of the spacer 86 typically defines the distance between the magnetically permeable portion 82 and the conductive portion 90. The magnetically permeable portion 82 may be provided as four separate portions or components 82a, 82b, 82c, and 82d, as discussed further herein. Each component may be positioned near each of the coil groups 34, 36, 38, and 40, and near the corner of the conductive portion 90. The conductive component or portion 90 typically comprises a highly conductive material, such as high-purity copper or other suitable highly conductive material. The conductive component 90 allows eddy currents generated by induced currents due to the penetration of a magnetic field into the conductive material 90.

[0047] The positioner 20 may also include two housings or covers, including a first cover 100 and a second cover 104. The two covers surround all coil arrays 30, field-forming components 80, and structural or retaining members 110. Further, various feet or anti-slip elements 116 may be adhered to or attached to the housing portion 104 for selected operational purposes. Additionally, the housing, such as the first housing portion 100, may include selected ergonomic and support portions, including a hand hole or area 120 and shaped ergonomic portions. The shaped portions may include a neck support area 124 with lower or recessed portions 126 and 128 to assist in holding or positioning the patient's or subject's head or neck region for selected procedures. However, it should be understood that the shape and configuration of the cover 100 may be formed in any suitable shape. Further, the positioner 20 may have selected dimensions of length 20a, width 20b, and height 20c. The length 20a can be approximately 400mm to approximately 600mm, including approximately 450mm to approximately 550mm, including approximately 510mm. The width 20b can be approximately 400mm to approximately 500mm, including approximately 3000mm to approximately 400mm, including approximately 355mm. The height 20c can be approximately 10mm to approximately 55mm, including approximately 20mm to approximately 50mm, including approximately 35mm. (Continue to refer to...) Figure 1 And additionally refer to Figure 2A and Figure 2BAs described above, coil array 30 includes a plurality of individual coils. These plurality of coils may be configured as coil groups 34-40. As described herein, each coil includes various features. Furthermore, each coil may include substantially the same or similar features, which will not be repeated for clarity. Therefore, coil 34a will be discussed by way of example, and it should be understood that, unless otherwise stated, the other individual coils will have the same or similar features.

[0048] Coil 34a may be substantially formed as an ellipse having a primary axis 150 and a secondary axis 154. Coil 34a may be formed on a mold or template and then removed as it essentially comprises only the coil portion or conductive portion. However, the coil may include dimensions as discussed herein. Coil 34a may alternatively or in combination be formed or wound on a spool or wire holder. Figure 2B As shown, the wire can be wound around the spool or retainer, and the assembly can be inserted into the structural component 110.

[0049] The spindle 150 may include an inner spindle portion 150a, the internal dimensions of which, for example, a length of approximately 20 mm to approximately 50 mm, including approximately 31 mm to approximately 35 mm, and further including a dimension of approximately 33 mm. The spindle 150 may also include an outer spindle 150b, the outer spindle 150b including the internal dimension 150a, the internal dimension 150a including a dimension of approximately 40 mm to approximately 70 mm, further including a dimension of approximately 45 mm to approximately 55 mm, and further including a dimension of approximately 50 mm. Therefore, the coil 34a may be approximately 55 mm long along the outer spindle 150b.

[0050] The short shaft 154 may also include an internal dimension or length 154a and an external dimension or length 154b, wherein the external dimension 154b includes the internal dimension 154a. The internal dimension 154a may be from about 5 mm to about 20 mm, including from about 9 mm to about 11 mm, and further including about 10.5 mm. The external dimension 154b may be from about 20 mm to about 40 mm, further including from about 22 mm to about 32 mm, and further including about 27 mm. In various embodiments, the coil 34a may include an external main shaft dimension 150b of about 50 mm and an internal dimension 150a of about 33.68 mm. Further, the coil 34a may include a secondary shaft internal dimension 154a of about 10.68 mm and an external dimension 154b of about 27.5 mm.

[0051] It should be understood that each coil in coil groups 34, 36, 38, and 40 can be substantially identical. Therefore, the dimensions of each coil in coil groups 34–40 can be substantially the same as those described above.

[0052] Furthermore, coils such as coil 34a can be formed by winding a selected connecting material, such as 21 gauge copper wire wound around the outer dimensions of the inner main shaft and secondary shaft. The conductor typically conforms to NEMA MW-136C standards. Further, the conductor typically has a single layer of bonded polyurethane nylon insulation. Coil 34a can be formed by winding a pair of leads of the conductor. The conductor can be introduced into coil 34a as twisted pair leads 153, but the conductor is not twisted when the main and secondary inner dimensions of the coil are wound as wraps or coil portions 155. The number of windings can include approximately 5 to approximately 10 windings per layer and approximately 8–15 layers. In various embodiments, the coil can include 7 windings per layer and 12 layers. As mentioned above, the outer dimensions of the outer main shaft 150b and secondary shaft 154b can be equal to the outer dimensions of the outer main shaft 150b and secondary shaft 154b.

[0053] As discussed herein, the combination of TCA 30 and selected field forming components 80 can be used to form selected field geometries and variations, as further described herein. The field volume may include a navigable volume or navigation volume, which may be from about 400 cubic millimeters to about 600 cubic millimeters, including about 500 cubic millimeters. The navigation area or volume may begin about 50 mm above TCA 30. It will be understood by those skilled in the art that the coil, such as coil 34a, can be varied depending on the specifications of the remaining field forming components (e.g., size, type, material, etc.). However, it should be understood that when positioned in positioner 20, coil 34a may be substantially identical to each of the other coils in coil array 30.

[0054] Each coil of the coil assembly may be positioned within or on structural member 110. Structural member 110 may be made of a selected material that is generally inert and does not interact with a magnetic field. Further, the structural member may be made of a non-conductive material. The structural member may also typically include a selected stiffness to provide structural support to positioner 20.

[0055] Therefore, continue to refer to Figure 1 And additionally refer to Figure 3 -3B, the structural component 110 will be discussed in more detail. The structural component 110 may include multiple coil holding regions or portions 160, such as twelve coil holding regions 160a, 160b, 160c, 160d, 160e, 160f, 160g, 160h, 160i, 160j, 160k, and 160l. Similarly, as described above, each coil holding region 160a-160l may be configured to form or provide coil groups 34-40. Therefore, as... Figure 3 As shown, each group may include three coils. Therefore, for the purposes of the following discussion, it should be understood that individual coil groups may include those discussed below and Figure 3Features and components similar to those shown are not repeated for clarity of the present discussion. Structural components may have dimensions that fit within the overall dimensions of the positioner 20, including a length 110a of approximately 450 mm to approximately 550 mm, comprising approximately 450 mm, and a width of approximately 350 mm to approximately 450 mm, comprising approximately 350 mm. The dimensions of the portions accommodating the coil holding area or portion 160 may be smaller than the overall dimensions of the structural component 110, and may be approximately 330 mm to approximately 370 mm by approximately 430 mm to approximately 470 mm, comprising approximately 350 mm by approximately 450 mm.

[0056] Reference coil holding regions 160a, 160b, and 160c, each of which can hold coils 34a, 34b, and 34c respectively. Each coil holding region, for example... Figure 3A and 3B The coil holding region 160a shown may include a raised outer wall 164 that substantially holds the respective coils 34a in place. Further, a central pin or protrusion 166 may pass through the central portion 156 of a coil, such as a coil 34a. The pin 166 extends from the bottom or bottom surface 186 of the coil holding region 160a. As described above, the main inner shaft 150a and the secondary inner shaft 154a may define an opening 156 for the coil 34a or the spool holding the coiled portion. The protrusion 166 may enter or pass through the opening 156, and the outer wall 164 may be adjacent to the outer surface 158 of the coil 34a or the spool holding the coiled portion. Similarly, it should be understood that each of the plurality of coil holding regions 160 may include similar features.

[0057] Coil groups, such as the first coil group 34, may be positioned about a center point or region 170. The center point or region 170 may be the center point around which each coil 34a, 34b, 34c is positioned. Typically, each coil 34a, 34b, 34c is radially spaced from the center 170. However, coils 34a, 34b, 34c may not all be equidistant from the center 170 and / or may not be equidistant from each other. Each coil may be specifically spaced from the edge of the magnetically permeable member, with the corresponding coil group positioned on the edge of the magnetically permeable member. In various embodiments, the respective holding regions 160a, 160b, and 160c may be positioned relative to each other at a selected “clock angle,” such as approximately 120° around the center 170. However, it should be understood that the respective holding regions 160a, 160b, and 160c need not be spaced 120° apart, or not all of them need to be spaced 120° apart.

[0058] In various embodiments, for example, the coil holding region 160b may be on an axis or line 172 extending through the center of the coil holding region 160b and center 170. Similarly, a second axis or line 174 may extend through the center point 170 and the center of the coil holding region 160c. The angle 176 between the two lines 172 and 174 may be approximately 120°. However, it should be understood that, as described above, the positions of the coil holding regions relative to each other can be selected to achieve a selected type of field, such as appropriate differences in the field, and thus can be changed from the current illustration. However, the coil regions of each of the coil groups 34, 36, 38, and 40 may be configured to hold their respective coils about 120° apart around the center point 170. Further, as discussed above and herein, the differences may include differences in time based on the emission field from the coil group and the induced current field from the conductive member 90. The differences in the fields(one or more) assist in ensuring accurate and / or precise tracking of the selected tracking device.

[0059] In various embodiments, the respective coils 34a, 34b, and 34c in regions 160a, 160b, and 160c are spaced apart from the edges of the respective magnetically permeable members 82 on which these coils are placed by a selected distance. This distance can be the distance from the outer edge of the coil to the nearest edge of the magnetically permeable member. This distance can be from about 1 mm to about 50 mm, including from about 2 mm to about 40 mm, and further including from about 10 mm to about 40 mm, and further including from about 20 mm to about 25 mm. Another distance can be the distance from the outer edge of the coil to the farthest edge of the magnetically permeable member. This distance can be from about 30 mm to about 120 mm, including from about 50 mm to about 100 mm.

[0060] In various embodiments, in addition to those described above and / or in combination with those described above, the respective coils 34a, 34b, and 34c in the holding regions 160a, 160b, and 160c may be spaced apart from the corners and / or edges of the respective magnetically permeable members 82 on which these coils are placed by a selected distance. The respective coils 34a, 34b, and 34c and / or the holding regions 160a, 160b, and 160c may be positioned about a common center 170. The center of coil 34 and / or the center 166a of coil holding region 160 may be positioned from the common center 170 at a distance of approximately 10 mm to 50 mm, including from approximately 30 mm to approximately 40 mm from the common center 170. Further, the centers of coil 34 and / or the centers 166a of coil holding region 160 may be spaced apart from each other at a distance of approximately 20 mm to approximately 100 mm, including from approximately 50 mm to approximately 80 mm. Furthermore, the center of coil 34 and / or the center 166a of coil holding region 160 may be located at a distance from the nearest boundary edge of magnetically permeable member 82, which may be from approximately 20 mm to approximately 100 mm from the nearest boundary, including from approximately 40 mm to approximately 70 mm from the nearest boundary. The center of coil 34 and / or the center 166a of coil holding region 160 may be located at approximately 80 degrees to approximately 160 degrees about the common center 170, including from approximately 120 degrees about the common center 170. One of the coil centers may be located at approximately 0 degrees to approximately 20 degrees from the diagonal of magnetically permeable member 82. The axis of the major axis or principal axis 150 of coil 34a may vary from approximately 0 degrees to approximately 90 degrees relative to the nearest boundary line or tangent of magnetically permeable member 82. It should be understood that each coil of the various coil groups 34, 36, 38 and 40 may be constructed as described above. Furthermore, each coil may be modified to achieve a selected field geometry.

[0061] Continue to refer to Figure 3 And further refer to Figure 3B The coil holding region may also include a geometry relative to a substantially flat plane 184. As discussed further herein, the flat plane 184 may be any suitable plane, such as the plane defined by the surface of the field-forming portion 80, and in particular the plane defined by the surface of the magnetically conductive portion 82.

[0062] Similarly, Figure 3As shown, the coil holding region 160c may include a bottom surface 186 on which a coil, such as coil 34c, may rest when positioned within structural member 110. The bottom surface 186 of the coil holding portion 160c contacts or holds coil 34a in a position and orientation. The bottom surface 186 may define a plane 190 that orients or positions coil 34a relative to plane 184. Plane 190 may be parallel to or intersect plane 184 at an angle, such as from about zero degrees (º) to about 70º, including about 90º, and further including from about 0º to about 60º. In various embodiments, the plane 190 defined by the bottom surface 186 may extend at an angle 192 relative to a line 194 orthogonal to the bottom plane 184. Angle 192 may be from about zero degrees (º) to 180º, including about 90º, and further including from about 30º to about 150º, including about 90º. In various embodiments, each coil holding region 160a-160l may include the same angle 192; however, in various embodiments, at least one of the holding regions 160a-160l may include an angle 192 different from the others. Further, it should be understood that the bottom surface 186 of each coil holding region 160a-160l may be inclined along the main axis of the respective coil, the secondary axis of the respective coil, or a combination thereof. Therefore, in various embodiments, the coil 34a may be positioned relative to the plane 184 at any suitable angle. Thus, the coil 34a may not have a top or bottom surface substantially parallel to the plane 184. Instead, the coil 34a may be inclined relative to the plane 184. As further discussed herein, the positioning of the coil 34a relative to the plane 184 may be the position of the coil 34a relative to the plane defined by the magnetic field shaping portion 82 to assist in forming or generating selective field differences. Similarly, as described above, each coil holding portion 160 may include similar or identical features and dimensions, as described above.

[0063] Additional reference Figure 4 and Figure 4A And continue to refer to Figure 3 The structural component 110 includes a field-forming assembly contact side or holding side 114 opposite to the coil holding side 112. The field-forming assembly holding side 114 of the structural component 110 may include various features, such as a main cavity or expansive pocket 200 having a main surface or base surface 202 and a wall 204 extending 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 or constructed as a single piece (e.g., a single unit) of material. In various embodiments, the conductive member 90 may be formed as a plurality of electrically connected or electrically isolated members across the entire surface of the expansive pocket 200.

[0064] The coils of the coil array 30 are held in the coil holding portions 160a-160i, while the main surface 202 and the upright wall 204 assist in holding the conductive member 90 relative to the coil array 30. The dimensions of the upright wall 204 may be substantially equal to or interference-fitted with the conductive member 90. Furthermore, various adhesives or holding materials or components (e.g., rivets, screws, etc.) may be used to fix or hold the conductive member 90 relative to the structural member 110.

[0065] Structural component 110 may also include a recess 220, which may be referred to as a small recess or coil assembly recess 220. The small recess 220 may include a main surface 222 and an upright wall 224. The upright wall may extend from the main surface 222 to the surface 202 of the conductive recess pocket 200. The dimensions of the upright wall 224 may be substantially equal to the external dimensions of the magnetically conductive component 82. The spacer component 86 may have dimensions equal to or slightly larger than the upright wall 224. Therefore, the conductive member 90 may press the spacer component 86 against the magnetically conductive component 82 and the surface 202 of the conductive recess 200 to assist in holding the spacer material 86 in place. Further, when the conductive member 90 presses against the spacer component 86, a force may be applied against the magnetically conductive component 82, which is then pressed against the magnetically conductive component 82 to allow it to enter the small recess 220.

[0066] It should be understood that each coil group, including coil groups 34, 36, 38, and 40, may each include a separate recess. For example... Figure 1 As shown and further discussed herein, for each coil group or transistor 34, 36, 38, and 40, the magnetically permeable component 82 may be formed as an independent unit or component (or a stacked component with the same peripheral dimensions). Therefore, each magnetically permeable component 82 may be positioned in a separate recess 220. Thus, by defining or forming the recesses 220, the structural component 110 provides physical spacing between each magnetically permeable component 82. Typically, the recesses 220 are formed to hold the magnetically permeable component 82 near the coil group 34 but not in contact with another magnetically permeable component 82. The magnetically permeable components 82 may be spaced apart by distances 330', 330'' ( Figure 5A The distances 330' and 330'' can be approximately 1mm to approximately 200mm, including approximately 1mm to approximately 100mm, including approximately 10mm.

[0067] It should be understood that each element, including the TCA 30, the magnetic conductor 82, the spacer 86, and the conductive member 90, can be selectively adhered to or fixed to the structural member 110. For example, adhesives or epoxy resins such as Locktite® brand adhesives or epoxy resins can be used to fix all or some portions of the coils and field forming members 80 to the structural member 110. Thus, when each coil of the TCA 30 and the field forming member 80 is fixed to the structural member 110, the TCA 30 and the field forming member 80 can be substantially fixed in three-dimensional space relative to each other.

[0068] like Figure 1 As shown, the field shaping assembly 80 includes various parts and components, which will be discussed further herein. As described above, the TCA 30, comprising various individual coil components or portions, can be driven to generate an electromagnetic field. As will be understood by those skilled in the art, the electromagnetic field may extend from the TCA 30. As described above, the electromagnetic field may affect tracking devices, such as instrument tracking device 52 and / or DRF tracking device 54. Tracking devices 52, 54 sense the electromagnetic field, and the positioning of tracking devices 52, 54 can be determined relative to each other. Housing or enclosure components 100, 104 may be substantially inert and / or do not affect the electromagnetic field. In various embodiments, housing portions 100, 104 may also be substantially resistive.

[0069] Continue to refer to Figure 1 And additionally refer to Figures 5A-5B The field forming assembly 80 may include one or more magnetic or magnetically conductive portions 82, substantially inert spacer portions 86, and conductive members 90. For example... Figure 1 , Figure 5A and Figure 5B As shown, the conductive member 90 may include a first surface 260 having a surface area. The surface area of ​​surface 260 may be substantially continuous and extended, or defined by the lengths of a first edge 262 and a second edge 264. As is generally understood in geometry, the surface area of ​​surface 260 may be the product of two lengths 262 and 264.

[0070] The magnetically permeable member 82 can be configured as a plurality of magnetically permeable members 82a, 82b, 82c, and 82d. Each magnetically permeable member 82 may have substantially similar or identical dimensions and may include corresponding first surfaces 270a, 270b, 270c, and 270d. Each surface 270 may include substantially similar surface areas and is defined by corresponding edges 274 and 276. Likewise, as understood in geometry, the surface area of ​​each surface 270 will be the dimension of edge 274 multiplied by the dimension of edge 276.

[0071] The size and dimensions of the magnetically permeable component 82 can be designed to be positioned relative to each coil group 34, 36, 38, 40. For example, refer to... Figure 5A Coils 32a, 32b, and 32c (shown in dashed lines) are positioned on structural member 110 on coil array side 112. The structural member physically separates coils 34a, 34b, and 34c from magnetically permeable member 82a, but the magnetic field generated by coil group 34 may be affected by magnetically permeable member 82a and conductive member 90. Similarly, it should be understood that coils 34a, 34b, and 34c can be positioned approximately 120 degrees apart, such that axis 172 extending through the center of coil 34b and center 170, and a second axis 174 extending through center 170 and the center of coil 34a, are positioned at an angle 176 to each other. Angle 176 allows each of coils 34a, 34b, and 34c to be positioned approximately 120° apart around center 170.

[0072] It should also be understood that spacer 86 may be positioned between conductive member 90 and each of magnetically permeable members 82a, 82b, 82c, and 82d. It should be understood that spacer 86 may be configured as a large single spacer whose surface area covers an area equal to the external dimension defined by all magnetically permeable members 82 and / or conductive members 90; alternatively or otherwise, a separate spacer may be provided for each magnetically permeable member 82. Spacer 86 is substantially inert to both current and magnetic fields. Therefore, spacer 86 can be formed in a highly efficient assembly and manufacturing manner, thus allowing for a single spacer for each magnetically permeable member 82, rather than a single large spacer.

[0073] Additional reference Figure 5B The conductive member 90 may be selected from a suitable conductive material. The conductive material may include a high-purity copper sheet, such as copper sheet C101A-02 that meets material standard ASTN F-68. The conductive sheet 90 may have a suitable thickness 279, for example, from about 0.5 mm to about 3 mm, including from about 1 mm to about 2 mm, and further including about 1 mm. The conductive member 90 may also have a side surface 262 with a length of about 400 mm to about 500 mm, further including from about 420 mm to about 450 mm, further including from about 438.5 mm to 439.5 mm, and further including about 439 mm. An edge or side surface 264 may have a dimension of about 320 mm to about 350 mm, further including from about 335 mm to about 345 mm, further including from about 338.6 mm to about 339.2 mm, and further including about 338.9 mm.

[0074] The magnetically permeable component 82 can be selected from any suitable high-permeability material that is substantially non-conductive and has high magnetic saturation, low coercivity, and low-frequency dispersion. For example, the magnetically permeable component can be formed from Finemet® nanoparticle crystal material sold by Hitachi Metals, Ltd., which has business locations in Tokyo, Japan and Novi, Michigan. The magnetically permeable component 86 may include material having manufacturer number MS-FR code FIAH0535. Typically, each magnetically permeable component 86 may be formed from a multilayer of nanoparticle crystal material stacked together and held together using a selected adhesive. It should be understood that the magnetically conductive material may include suitable or selected materials, such as Finemet® nanoparticle crystal material, or the magnetically conductive material Magnetic 2605SA1 or 2605HB1M alloy sold by MetGlas, Inc., Hitachi Metals, USA.

[0075] The magnetically permeable member 82 may have selected dimensions, including lengths on sides 274 and 276. For example, the dimension of side 274 may be from about 100 mm to about 200 mm, further including from about 156 mm to about 157 mm, and further including about 156.50 mm. Side 276 may include a length from about 70 mm to about 190 mm, further including a length from about 132 mm to about 133 mm, and further including a dimension of about 132.2 mm. As described above, each magnetically permeable member 82a, 82b, 82c, and 82d may have substantially the same dimensions.

[0076] The magnetically permeable component 82 can be formed as a multilayer of Finemet® magnetically permeable material stacked on top of each other. The number of layers can be from about 8 to about 20, including from about 11 to about 13, and further including about 12. In various embodiments, the number of layers can further include about 15. These layers can be stacked together with a selected sheet of material comprising an adhesive material that is substantially electrically and magnetically inert. Figure 5C As shown, the magnetically permeable member 82 may also include a thickness 280 of about 0.1 mm to about 0.2 mm, and further includes a thickness 280 of about 0.12 mm.

[0077] Reference Figure 6 A schematic diagram of magnetic field lines from two coils, such as coils 34a and 34b, is shown. Coil 34a is schematically shown to generate a solid field line 300, and coil 34b includes a dashed field line 320. Coils 34a and 34b are shown positioned above or near the field shaping assembly 80 and within the structural member 110. The field shaping assembly 80 includes the components discussed above, including separate magnetically permeable members, such as magnetically permeable member 82a and conductive member 90, separated by a spacer member 86. Figure 6As shown, coil group 34 is positioned near magnetically permeable member 82a, and coil group 36 is positioned near magnetically permeable member 82b. Furthermore, the magnetically permeable members are separated by space 330. Therefore, as... Figure 6 As shown, field lines 300 and 320 can interact with both the magnetically permeable member 82a and the conductive member 90. This allows the vectors defined by field lines 300 and 320, also known as field line vectors or field vectors, to have selected differences (e.g., different angles between two vectors at a single location in space). Different fields can include fields having vectors with approximately 50 degrees to approximately 130 degrees relative to each other, including approximately 54 degrees to approximately 125 degrees, and further including approximately 54.7 degrees and approximately 125.3 degrees.

[0078] In various embodiments, a single point or location in space 340 may be defined by two vectors: a first vector 344 associated with magnetic field lines 300a generated by coil 34a, and a second vector 346 defined by magnetic field lines 320a generated by coil 34b. An angle 348 exists between the two vectors 344 and 346. This angle can be equal to or greater than 0 degrees to less than or equal to 180 degrees. If the angle is equal to 0 degrees or 180 degrees, the two vectors 344 and 346 are linearly related. If the angle is greater than 0 degrees to less than 180 degrees, the two vectors 344 and 346 are linearly independent. If the angle is equal to 90 degrees, the two vectors 344 and 346 are orthogonal. The angle 348 between vectors 344 and 346 can be used to calculate the location 340 in three-dimensional space. The calculation of the position of point 340 in three-dimensional space can be similar to what those skilled in the art understand, and can be based on a previously determined representation such as a lookup table, which is determined and stored based on calibration field measurements at multiple locations defined by field lines 300, 320 in the navigation space.

[0079] The angle 348 between the two vectors 344 and 346 of lines 300 and 320 may differ from the angle 360 ​​between the two vectors 362 defined by field line 300b and the vector 364 defined by field line 320b. The different angle 360 ​​between the two vectors 362 and 364 allows for different information regarding the position 370 at the origin of the two vectors 362 and 364. Furthermore, as... Figure 6 As shown, magnetic field lines 300 and 320 allow for significant differences in the measurable vector at different locations relative to coils 34a and 34b in navigation space 41. (Additionally, see...) Figure 7At a set of different locations, if most pairs of field vectors at those locations are orthogonal or nearly orthogonal, the fields can be considered distinct and / or have selected differences. As examples and / or alternative examples, if most pairs of field vectors, including a selected number, have angles equal to or greater than about 54.7° to angles less than or equal to 180° minus that selected angle, or about 125.3°, the fields can be considered distinct. As another example, if most pairs of field vectors have angles equal to or greater than about 50° to angles less than or equal to about 130°, the fields can be considered distinct. While not bound by theory, it should be noted that the angular ranges in these examples are centered around an orthogonality of approximately 90°. Furthermore, distinct fields can provide accurate, precise, and reliable navigation. At a set of different locations, if most pairs of field vectors at those locations are linearly dependent or nearly linearly dependent, the fields can be considered indistinguishable. As an example, if most field vector pairs have angles equal to or greater than about 0° to less than or equal to about 50°, or equal to or greater than about 130° to less than or equal to about 180°, then the fields can be considered to be indistinguishable.

[0080] In various embodiments, field lines 300, 320 can be substantially different and typically extend away from field shaping assembly 80, such as in the direction of arrow 380. Therefore, field lines 300, 320, together with the field lines and fields generated by all the coils in TCA 30, can define a navigation space or navigable volume. Thus, the navigable space can typically be located away from field shaping assembly 80. Therefore, field shaping assembly 80 also typically allows any magnetic field interference located away from TCA 30, such as magnetic field interference objects on the side of field shaping assembly 80 opposite to TCA 30, to substantially not affect the navigable space generated in the direction of arrow 380.

[0081] The TCA 30 can typically be operated to transmit in a power range of approximately 1.0 nanowatts (nW) to approximately 1.0 milliwatts (mW), including a power range of approximately less than 0.1 milliwatts. However, it should be understood that the TCA 30 can be operated to transmit at any suitable selected power.

[0082] Continue to refer to Figure 6 and further refer to Figure 7 , Figure 7 A graphical representation of possible field differences is shown. The y-axis represents the percentage of angles felt by field vectors at a set of locations, and the x-axis represents the angle between two determined vectors. The difference is the distinction between two vectors that have the same original space in space, where the vectors are defined by field lines of the field generated by the TCA 30.

[0083] like Figure 7As shown, if multiple transmitting coils, such as conductive transmitting coils, such as the aforementioned coils, are arranged substantially flat on a plane without any field shaping, the percentage of vectors measured at a specific angle is shown in graphic area 390. As shown, since almost all vectors have an angle difference close to 0° or close to 180°, there is essentially no angular difference. Those skilled in the art will understand that the field lines are generated substantially along one direction relative to the flat coil array and do not produce a significant degree of difference between the field lines. For coil arrays positioned in an orthogonal configuration with concentric and orthogonally oriented triple coils, such as the coil array in the AxiEM™ electromagnetic navigation system, the difference is shown in graphic area 392 and includes a larger difference in the angular difference between the measured field lines from the constructed coils. Finally, in various embodiments, the positioner 20, including the TCA 30 and the field shaping assembly 80, exhibits a larger difference, as shown in graphic representation 394. In other words, the curves of the measured angular difference between two vectors at different points are orthogonal or nearly orthogonal and expand to include more than just a few angular differences. For example, the angles between vectors measured based on the field lines generated by the positioner 20 can have a wide range of angular differences, such as between approximately 50 degrees and approximately 130 degrees between vectors measured at different points. The greater angular differences between vectors measured at different points provide additional or more information for the navigation of the tracking device used to measure the magnetic field generated by the coil array 30.

[0084] The positioner 20, including the field shaping component 80, is configured to generate differences in field lines or angular differences between vectors defined by field lines, as described above. Specifically, the magnetically permeable component 82 can absorb and deflect a portion of the magnetic field. For example, each layer of the magnetically permeable component 82 can absorb and deflect a certain amount of field before becoming saturated. Typically, the magnetically permeable component 82 is capable of absorbing and deflecting substantially all magnetic fields in contact with it, but some magnetic fields originating from coil 34a and coil group 34 may leak and affect the conductive component 90. However, as described above, each of the coil groups 34, 36, 38, and 40 includes a separate magnetically permeable portion with a space 333 between the coil groups. Therefore, at least a portion of the field generated by the coil groups 34, 36, 38, and 40 can interact with the conductive component 90. When the magnetic field interacts with the conductive component, eddy currents 90 may be generated. In various embodiments, eddy currents may be formed around the magnetically permeable component 82 on the conductive component 90.

[0085] Next, eddy currents can also generate electromagnetic fields that are typically generated and formed in navigation space. The induced magnetic field generated by the conductive member 90 can be proportional to the time derivative of the magnetic field generated by the TCA 30. As will be understood by those skilled in the art, in terms of the complex function of time, the induced field generated by the eddy currents in the conductive member 90 can typically be out of phase with the induced field generated by the TCA 30, and approximately 90° out of phase. Thus, the induced field is different from (e.g., orthogonal or nearly orthogonal) to the field generated by the TCA 30. As described above, the field generated by the eddy currents in the conductive member 90 can also be incorporated into the navigation space and used by the navigation system 76 to determine the position of the tracked member and the tracking device.

[0086] Reference Figure 8 Flowchart 395 is shown. Flowchart 395 can be incorporated into an algorithm that includes instructions that can be stored on a storage or memory system, such as the memory system of navigation system 10, as discussed further herein. The instructions can be executed by navigation processor 76 or other suitable processor. Flowchart 395 can allow determination or navigation based on the field formed by TCA 30 and the field generated due to eddy currents in conductive member 90.

[0087] In flowchart 395, in first block 395a, current is driven into the coils of TCA 30 to generate a magnetic field as a complex function of time. Each coil of TCA 30 can be driven in various multiplexing modes to allow differentiation of each field generated by each coil. Multiplexing can include frequency multiplexing, time multiplexing, code multiplexing, and / or combinations of multiplexing. After using the TCA 30 to drive the current to generate the magnetic field, in block 395b, a tracking device, such as tracking device 52 of instrument 50, can sense the total magnetic field as a complex function of time.

[0088] Then, in block 395b, the sensed total magnetic field can be transmitted to a processor system, such as the navigation processor 76 as described above, which may include or access instructions to decompose the real and virtual magnetic field components sensed by the tracking device. It should be understood that any suitable processor system or specially designed processor or general-purpose processor executing code can be used for the decomposition of the real and virtual components of the magnetic field. As will be generally understood by those skilled in the art, the decomposition of the real and virtual magnetic field components in block 395c can be based on well-known calculations. However, the decomposition of the real and virtual magnetic field components allows for a more detailed analysis of the sensed total magnetic field, allowing for higher tracking accuracy of the tracking device 52. Furthermore, by taking into account the real and virtual magnetic field components, the field generated due to the eddy currents in the conductive member 90 can be used to provide additional field differences and tracking information for the navigation of the instrument 50.

[0089] Therefore, in block 395d, navigation of instrument 50 by sensing the magnetic field using tracking device 52 allows navigation on both real and virtual magnetic field components. As described above, and further as further herein, navigation system 10 can be used to navigate the position of instrument 50 by sensing a field generated by locator 20, which may include a field generated by TCA 30 and a field generated due to eddy currents in conductive member 90. Furthermore, the eddy currents generated in conductive member 90 can be based on the shape, size, and position of magnetically permeable member 82 relative to conductive member 90. Thus, as described above, the shape and position of the coil of TCA 30 and the shape and position of field shaping member 80 can generate a field that allows navigation of instrument 50.

[0090] Reference Figure 9 As described above, a locator 20 may be used in the navigation system 10. The locator 20 can be positioned relative to a subject, such as a patient 400, while a user 402 operates or moves an instrument 50, which has an associated tracking device 52. A DRF 54 may be connected to the subject 400. The subject 400 may be positioned near or adjacent to the locator 20. The locator 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 locator, such as an optical locator 420.

[0091] Tracking information, including magnetic fields sensed by tracking devices 52, 54, can be transmitted to navigation processor 76 via a communication system such as a coil array and tracking device controller 430. Navigation processor 76 may be part of a workstation or computer system 434, which includes a display 436 for displaying image 440. Further, the tracked position of instrument 50 may be shown as an icon 442 relative to image 440. Various other memory and processing systems may also be provided, such as a memory system 446 communicating with navigation processor 76 and imaging processing unit 448. As described above, image processing unit 448 may be integrated into imaging system 450, such as an O-arm® imaging system. Imaging system 450 may be an X-ray imaging system including an X-ray source 452 and a detector 454 movable within a gantry 460. Imaging system 450 may also utilize tracking device 464 for tracking.

[0092] Information from all tracking devices can be transmitted to the navigation processor 76 for determining the position of the tracked parts relative to each other and / or for locating the instrument 50 relative to image 440. Imaging system 450 can be used to acquire image data to generate or produce image 440 of subject 400. However, it should be understood that other suitable imaging systems may also be used. As described above, coil array controller 430 can be used to operate and power TCA 30 and locator 20.

[0093] As described above, the positioner 20 may include various components, including a TCA 30, which includes one or more coils positioned relative to each other, and other components such as the field forming assembly 80. As described above, the field forming assembly 80 may be positioned within a retaining structure and includes various other portions such as one or more cover portions 100, 104, and retaining portions such as the structure or retaining member 110. As described above, the positioner 20 includes the TCA 30 positioned relative to the field forming assembly 80 on the structural member or positioner 110. As described above and as... Figure 1 As shown, the field shaping assembly 80 includes multiple portions, such as magnetically permeable members 82, positioned relative to a coil assembly, such as coil group 34. The multiple magnetically permeable members 82 are positioned spaced apart from each other relative to a single conductive member 90. Therefore, the positioner 20 may include multiple coil assemblies in the TCA 30, which are positioned relative to multiple magnetically permeable members 82, all of which are positioned relative to a single or one conductive member 90. It should be understood that, according to various embodiments, the positioner 20 may include different configurations, including coil assemblies, magnetically permeable members or single members 82, and conductive members 90 in the TCA 30.

[0094] According to various embodiments, refer to Figure 10A and Figure 10B Positioner 20 or other suitable positioners, including those further discussed herein, may include... Figure 1 The positioner 20 shown is similar to other components or portions. However, according to various embodiments, the positioner 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 a group of coils, which may include one or more coils, such as coil 534. It should be understood that the discussion of coil 534 herein may refer to multiple coils, such as multiple coils in a group of coils like the coil group 34 described above. Therefore, the discussion of coil 534 as a single coil is merely exemplary, and similar to the coils in the coil group described above, coil 534 and associated components may be repeatedly and selectively shaped to generate selectively shaped (e.g., different) fields, which include selected or appropriate differences such as those described above.

[0095] Continue to refer to Figure 10A and 10BThe coil 534 may be positioned within a cup-shaped or well-shaped field forming assembly 580. As described above, the field forming assembly 580 may include a conductive member 590 and one or more spacer portions 586. It should be understood that the spacers 586 are optional and not required between the conductive member 590 and the well-shaped or cup-shaped magnetically permeable member or layer 582. The conductive member 590 may be formed of materials including those described above. Further, the magnetically permeable member 582 may also be formed of similar materials as described above. The cup-shaped magnetically permeable member may be provided to shape and guide the emission field formed by the coil 534, for example, away from the coil 534, but within the outer wall 600.

[0096] The cup-shaped magnetically permeable member 582 may include various parts or components, such as a wall or a raised sidewall 600. The raised sidewall may extend from the bottom wall 602, on 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 wall or central wall or extension 604 may also extend from the bottom wall 602 and / or through the coil 534. (As in...) Figure 10A As specifically described, the short wall 604 extends through the coil 534. The short wall 604 may serve as the core of the coil 534. However, it should be understood that the short wall portion 604 may only extend through or into a portion of the coil 534, as shown by the dashed line 604'.

[0097] The magnetically permeable member 582 can interact with the field emitted or generated by the coil 534 in a manner similar to that described above. Given the shape and / or position of the magnetically permeable member 582, the field or field lines formed by the coil 534 can be positioned or shaped relative to the conductive member 590.

[0098] Furthermore, coil 534 can be positioned substantially perpendicular to conductive member 590. In other words, the central axis 534a, or the axis around which coil 534 is wound, can be formed at an angle or positioned at an angle 534θ relative to the surface of conductive member 590. In various embodiments, axis 534a can be substantially perpendicular, for example, angle 534θ is 90 degrees, or it can be an angle other than 90 degrees. For example, angle 534θ can be about 40 degrees to about 150 degrees. As described above, positioning coil 534 within magnetically permeable member 582 can position or move the field formed by coil 534 relative to conductive member 590. It should also be understood that coil 534 and magnetically permeable member 582 can be formed as a single element such that low wall 604 can be positioned along axis 534a and can also move relative to conductive member 590 at a selected angle or at a position of selected angle 534θ.

[0099] Continue to refer to Figure 10A And additionally refer to Figure 10C and 10DThe cup-shaped or well-formed permeable magnetic component 582 can be selectively sized and / or shaped relative to the coil 534. For example... Figure 10C As shown, the magnetic cup 582 includes a cup portion 582', which includes a sidewall 600'. The sidewall 600' is positioned at a height of 601' from a bottom surface or plane, such as a bottom wall 602'. The height 601' can also be relative to the surface of the conductive member 590, and is merely exemplary from the bottom wall 602'. However, the height 601' can be less than... Figure 10A The height of the magnetically conductive member 582 shown is 601. Further, according to various embodiments, the magnetically permeable member 582' does not include and does not need to include a short wall 604. It should also be understood that, according to various embodiments, the spacer 586 may include an air gap or space between the magnetically permeable member 582' or the magnetically permeable member 582 or 82 and the corresponding conductive member.

[0100] Coil 534 can be positioned relative to the magnetically permeable member 582' in any suitable manner, for example using spacer 605, which can be formed of a substantially inert material (e.g., non-conductive and / or non-magnetically disturbing or distorting, such as non-conductive cloth or other textile or polymeric materials). Thus, as described above, coil 534 can be positioned relative to the magnetically permeable member 582' to form a magnetic field relative to the conductive member 590. However, the shape and position of the magnetically permeable member 582' can affect or shape the field formed or emitted by coil 534. Similarly, spacer 586 can be selectively positioned between the magnetically permeable member 582' and the conductive member 590, or can be selectively left unpositioned. Further, as described above, the emitted field from coil 534 can induce a current in the conductive member 590, which then generates an induced field. The induced field can be different or have different components relative to the emitted field. Shaping and / or angulating the magnetically permeable member 582' relative to the conductive member 590 can further create different fields.

[0101] Continue to refer to Figure 10A And additionally refer to Figure 10D The diagram illustrates a magnetically permeable member 582''. The magnetically permeable member 582'' includes a sidewall 602'' having a height 601'' relative to the bottom wall 602''. Similarly, the height 601'' can vary, for example, be less than or equal to the height 601'. In various embodiments, the height 601'' can be such that the sidewall 602'' includes an upper surface or terminal surface or edge 603 below a portion of the coil 534, such as including at least the top portion. Therefore, it should be understood that the magnetically permeable member 582 can be shaped relative to the coil 534, or can be shaped relative to any suitable coil used to form the locator 20 or to shape the locator 20 to shape a selected field.

[0102] As an addition to or alternative to the embodiments of the TCA 30 and its various coils and coil groups described above, the positioner 20 may include the various embodiments discussed and illustrated herein. It should be understood that while exemplary coils or coil groups may be discussed, multiple coils or coil groups may be included in a single positioner, such as the positioner 20 described above.

[0103] Reference Figure 11A , Figure 11B and Figure 11C The diagram illustrates a field-forming component according to various embodiments. The field-forming component may include a substantially circular geometry, including, for example... Figure 11A The field-formed component or assembly 680 shown. For example... Figure 11B As shown, the field-forming component or assembly 780 may include an elongated or oval shape, as discussed further herein. Further, as... Figure 11C As shown, the field forming component or assembly 880 may include various shapes, such as rounded triangles, rounded-corner triangles, or other complex shapes. Therefore, the positioner 20 or any suitable positioner may include field forming components or assemblies such as circular field forming component 680, oval field forming component 780, or complex-shaped field forming component 880. As described above, each field forming component or assembly may have a coil positioned relative to it.

[0104] Additional reference Figure 11A The field forming member 680 may have a coil, such as coil 634, positioned relative to it. Coil 634 may be positioned at the center 690 of the field forming member 680. However, it should be understood that the central axis (e.g., the axis around which coil 634 is wound) may be eccentrically positioned or positioned away from the center 690 of the field forming member. However, the field forming member 680 may include a magnetically permeable member or portion 682 having a radius 682r. The field forming member 680 may also include additional portions or members, such as those described above that include the conductive layer portion 690. As described above, one or more spacer portions may be positioned between the magnetically permeable member 682 and the conductive member 690. According to various embodiments including those described above, the field forming member 680 may also include a second or auxiliary magnetically permeable member or portion 696. Thus, the field forming member 680 may include a conductive member 690 positioned between the first magnetically permeable member 682 and the second magnetically permeable member 696. Thus, the first magnetically permeable member 682 and the second magnetically permeable member 696 are on opposite or opposite sides of the conductive member 690. It should be understood that various shapes of field-formed components may also include this configuration or arrangement.

[0105] In various embodiments, a magnetically permeable member positioned on the side of the conductive member away from the coil of the emitting field can assist in absorbing additional fields from the coil that extend beyond the conductive member. For example, a second magnetically permeable member 696 can absorb the field formed by the coil 634 extending beyond the conductive member 690. Therefore, interfering objects or objects on the side of the conductive member away from the coil 634 are unlikely to have an effect or have induced a current therein. It should be understood that second or auxiliary magnetically permeable members of the field shaping assembly according to various embodiments can produce the same or similar effects.

[0106] Furthermore, each component or part may be positioned relative to each other. For example, the conductive component 690 may include an area or region 690a extending beyond the outer edge of the first magnetically permeable component 682, and the second magnetically permeable component 696 includes an area or region 696a extending beyond the edge of the conductive component 690. It should be understood that the second magnetically permeable component 696 may be optional and is not necessarily required or necessary to include in the field forming component 680. Furthermore, according to various embodiments, the second magnetically permeable component may be included in any suitable field forming component assembly, including the field forming assembly 80 described above (such as...). Figure 1 (as shown) and / or other field forming components including field forming component 580.

[0107] Go to Figure 11B The field forming component 780 may include a first magnetically permeable component 782 positioned on or relative to the conductive component or component 790, and a second magnetically permeable component 796. As described above, each respective component, such as the conductive component 790 and the second magnetically permeable component 796, may have an edge extending beyond the component or extending above the component. Therefore, the field forming component 780 may also include the first magnetically permeable component 782 and the second magnetically permeable component 796 positioned therebetween the conductive component 790. However, it should also be understood that the second magnetically permeable component 796 is optional.

[0108] The field forming component 780 may include a coil 734 or be positioned relative to the coil 734. The center of the coil 734c may be positioned away from or off-center from the center or point 782c of the first magnetically permeable member 782. The shape of the first magnetically permeable member 782 may include a first distance or radius 782r' and a second distance or radius 782r''. The two radii 782r' and 782r'' may be different to provide or impart a selected shape to the magnetically permeable member 782. Further, the coil 734 may be positioned such that the center or central axis 784c is positioned at point 782c. The coil 734 may be positioned at different locations relative to or on the magnetically permeable member 782 to achieve a selected shape of the magnetic field formed by the coil 734, as described above, thereby including or creating a selected magnetic field difference.

[0109] Go to Figure 11C The field forming assembly 880 may include a first magnetically permeable member 882, a conductive member 890, and a second magnetically permeable member 896. Similarly, the second magnetically permeable member 896 is optional, but if selected, the conductive member 890 may be positioned between the first magnetically permeable member 882 and the second magnetically permeable member 896. The shape of the first magnetically permeable member 882 may be a selected shape, such as a complex shape including a generally triangular portion 882t and a rectangular portion 882r. The first magnetically permeable member 882 may be formed as a single piece, but may include, for example, a... Figure 11C The selected shape is shown. However, it should be understood that, as further discussed herein, the field forming assembly may have an appropriate shape to achieve the selected differences. Thus, the coil 834 may be positioned such that the center or central axis 834c is located in one of the regions of the magnetically permeable member 882, such as in the triangle 882t. Furthermore, the connecting member 890 may extend beyond the outer edge or extent of the first magnetically permeable member 882, and the second magnetically permeable member 896 may extend beyond the extent of the connecting member 890.

[0110] like Figure 11A , Figure 11B and Figure 11C As shown, each coil 634, 734, 834 includes a generally circular periphery or a cylindrical shape. Therefore, the distance from the respective center to the outer periphery of the corresponding coil 634, 734, 834 can be substantially uniform around the outer periphery of the coil. However, it should be understood that, as mentioned above, the coil may include non-circular or cylindrical shapes, including oval or asymmetrical shapes. Furthermore, as also... Figure 11B and 11C As shown and as referenced Figure 11A As exemplarily described and discussed, each coil may be positioned at an asymmetric or off-center location on the corresponding field shaping assembly.

[0111] Reference Figure 11A , Figure 11B and Figure 11C The field forming component may include a single coil positioned relative to it. However, in various embodiments, multiple coils may be positioned relative to the respective field forming component. Furthermore, the multiple coils may be placed asymmetrically, for example, not equidistant from or separated from the edges of the respective field forming component.

[0112] like Figure 12A As shown, the selected field shaping component may include multiple coils positioned relative to it, as described above, such as Figure 1 As shown. See also: Figure 12AThe diagram illustrates a field shaping assembly 980. The field shaping assembly 980 may include a first magnetically permeable member 982 and a conductive member 980. Similarly, the field shaping assembly 980 may include an optional second magnetically permeable member 996, wherein the conductive member 990 is positioned between the first magnetically permeable member 982 and the second magnetically permeable member 996. The field shaping assembly 980 may have a selected shape, such as a generally triangular shape. Further, the coil assembly 40 may include a first coil 934a, a second coil 934b, and a third coil 934c. Each of the coils 934a, 934b, and 934c may be positioned away from the center of the triangle and / or close to a corner of the triangle. Each of the coils 934a, 934b, and 934c may have a corresponding center and may be substantially circular or cylindrical. However, as described above, due to the field shaping assembly 980, the coils can generate fields with significant differences.

[0113] Next refer to Figure 12B The diagram illustrates a field forming assembly 1080. The field forming assembly 1080 may be substantially rectangular and includes a first magnetically permeable member 1082 and a conductive member 1090. Similarly, an optional second magnetically permeable member 1096 is positioned such that the conductive member 1090 is between the first magnetically permeable member 1082 and the second magnetically permeable member 1096. As described above, each of the respective members 1090 and the second magnetically permeable member 1096 may have an outer extent extending beyond a selected distance or area of ​​an adjacent or next layer. Further, as described above, selected spacers may be positioned between each of the respective layers 1082, 1090, and 1096.

[0114] A coil assembly including first coils 1034a, 1034b, and 1034c can be positioned relative to the first magnetically permeable member 1082. The shape of each coil can be elongated, elliptical, or oval rather than circular. Therefore, each of coils 1034a, 1034b, and 1034c can generate or emit a field different from the field generated by the cylindrical or circular coil relative to the field shaping assembly 1080. Similarly, the corresponding shapes of the coils and the field shaping assembly 1080 can influence or generate selectively different fields as described above.

[0115] As in Figure 11A , Figure 11B , Figure 11C , Figure 12A , Figure 12B As discussed and illustrated, and in the various embodiments described above, different portions of the field forming component can be substantially independent of other field forming component portions. In various embodiments, such as Figure 1As shown, multiple coil groups can be positioned relative to multiple individual magnetically permeable members 82, all of which are positioned on individual or integral conductive members 90 of the field forming assembly 80. It should be understood that alternative and / or additional embodiments may be used alone or in combination with the field forming assembly 80, or as understood by those skilled in the art.

[0116] Go to Figure 13 The diagram illustrates a field shaping assembly 1180. The field shaping assembly 1180 includes various components, such as a first magnetically permeable member 1182, a conductive member 1190, and a second magnetically permeable member 1196. The first magnetically permeable member 1182 may be provided as one or more members formed as substantially single elements or spaced apart from each other, such as a first spacer 1200 and a second spacer 1204, but positioned above or on the connecting member 1190. Thus, as... Figure 13 As shown, the conductive member 1190 may have an outer edge 1206 that extends beyond the outer edge of any of the members 1182, which may include four magnetically permeable members 1182a, 1182b, 1182c, or 1182d. The conductive member 1190 may be provided as a single piece or formed as a single piece. As a single piece, the conductive member 1190 is conductive over its entire area.

[0117] The first magnetically permeable member 1182, positioned on or above the conductive member 1190, may be similar to Figure 1 The embodiment shown. However, it should be understood that various spacers can also be positioned between the magnetically permeable member 1182 and the conductive member 1190. However, as Figure 13 As shown, an alternative second magnetically permeable member 1196 may be positioned on the side of the conductive member 1190 opposite to the first magnetically permeable member 1182. The outer or outer extent 1210 of the second magnetically permeable member 1196 may extend beyond the outer extent 1206 of the conductive member 1190. However, it should be understood that the second magnetically permeable member 1196 may be provided as a single member, extending as a single member or formed as a single member within the extent 1210 of the magnetically permeable member 1196.

[0118] However, it should also be understood that the second magnetically permeable member 1196 is optional and not necessary. Furthermore, it should be understood that any suitable number of the first magnetically permeable members 1182 can be provided, and four are merely exemplary. Further, as described above, the field forming assembly 1180 can be provided as part of the positioner 20, including the TCA 30 and / or as... Figure 13The TCA 1130 is shown. The TCA 1130 may include multiple 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 coil group may include a selected number of coils, for example... Figure 13 The three coils shown include three coils 1134a, 1134b, and 1134c of the first coil group 1134; the first coil 1136a, the second coil 1136b, and the third coil 1136c of the second coil group 1136; the first coil 1138a, the second coil 1138b, and the third coil 1138c of the third coil group 1138; and the first coil 1140a, the second coil 1140b, and the third coil 1140c of the fourth coil group 1140. Fewer coil groups can also be provided if fewer than four magnetically permeable members 1182 are provided. However, each coil in each coil group 1134–1140 can generate a field relative to the field shaping assembly 1180.

[0119] However, the field shaping assembly 1180 combined with the TCA 1130 can generate selectively different fields as described above. The field shaping assembly 1180 may include various features, such as the shapes of the first conductive member 1182 including those described above, or any suitable shape. Furthermore, field differences can be achieved by positioning the coil of the TCA 1130 relative to the first magnetically permeable member 1182 in a selected or suitable manner. For example, asymmetrically placing the coil relative to the first magnetically permeable member 1182 can achieve suitable or selected field differences. Additionally, as described above, the extension of the emitted field beyond a portion of the first magnetically permeable member 1182 can induce a current in the conductive member 1190, which in turn generates an induced field.

[0120] Therefore, although in Figure 13 A rectangular member is shown, but it should be understood that the first conductive member 1182 can also be circular, trapezoidal, or other suitable shapes, even when placed on a generally rectangular conductive member 1190. Furthermore, the conductive member 1190 can be provided as a separate, independent component, for example, not as a single integral component, but as at least two components positioned between the first magnetically permeable member 1182 and the second magnetically permeable member 1196, with one or more conductive members 1190 therebetween. However, it should also be understood that the second magnetically permeable member 1196 is optional, so two or more conductive members 1190 can be positioned relative to the first magnetically permeable member 1182 to form a field-forming assembly 1180 together with the TCA 1130.

[0121] Furthermore, selected coils of coil groups 1134-1140 of TCA 1130 can be selectively shaped relative to selected field-forming parts of field-forming assembly 1180, such as into oval, circular, cylindrical, or other suitable shapes. It should also be understood that TCA 1130 may include the connections and control units described above for driving and otherwise operating the positioner 20. By way of example only, the coils of TCA 1130 are shown relative to field-forming assembly 1180, and other parts of the positioner assembly are not shown.

[0122] Therefore, as described above, the TCA according to various embodiments, including those discussed above in combination and / or alternative to each other, can be used to generate a field. Similarly, field shaping components according to various embodiments, including those discussed above as alternatives or additions to each other, can be used to selectively shape the field. As described above, the shaped field achieves a selected difference to allow tracking of a selected sensor within a navigation domain or volume. This difference provides or allows multiple vectors that are orthogonal or substantially orthogonal to each other to assist in improving the accuracy and / or velocity of determining the position of the tracking device. In various embodiments, the emission field relative to the induction field (i.e., generated by the induced current in the conductive member) may be or may be different. Therefore, a tracking coil or other sensor that has utilized the navigation domain to track space can be resolved substantially accurately or precisely in a three-dimensional space including X, Y, Z positioning and orientation, which includes at least one of yaw, pitch, or roll.

[0123] Field shaping components, such as field shaping component 80, or according to any suitable embodiment including those described above, may include magnetically permeable components and conductive components of the aforementioned materials. Therefore, various embodiments that can be combined or substituted for each other are discussed. However, as discussed herein, field shaping components are operable to significantly reduce or eliminate distortions or interferences that may be introduced by conductive components other than the field shaping component. Therefore, tracking of the tracking device in the navigation domain may be substantially unaffected by various components or materials that may affect the field generated by TCA.

[0124] Exemplary embodiments are provided so that this disclosure will be thorough and its scope fully convey to those skilled in the art. Various specific details, such as examples of specific components, apparatuses, and methods, are given to provide a thorough understanding of embodiments of the invention disclosed. It will be apparent to those skilled in the art that specific details are unnecessary, and that the exemplary embodiments can be implemented in many different forms, none of which should be construed as limiting the scope of the invention. In some exemplary embodiments, well-known processes, well-known apparatus structures, and well-known technologies are not described in detail.

[0125] The above description of the embodiments is provided for illustrative and descriptive purposes. It is not intended to be exhaustive or limiting of the invention. Even if not explicitly stated or described, individual elements or features of a particular embodiment are not generally limited to that particular embodiment, but are interchangeable and can be used in the selected embodiment where applicable. These elements or features can also be changed in many ways. Such changes should not be considered as departing from the invention, but all such modifications are intended to be included within the scope of the invention.

Claims

1. A field shaping assembly comprising: a conductive member having a first surface, the first surface having a first surface area; a first permeable magnetic member having a second surface, the second surface having a second surface area; a second permeable magnetic member having a third surface, the third surface having a third surface area; a structural member having a first set of coil retaining pockets, a second set of coil retaining pockets, a first pocket, a second pocket, and a third pocket, a first coil set located in the first set of coil retaining pockets and having a first plurality of coils associated with the first permeable magnetic member; and a second coil set located in the second set of coil retaining pockets and having a second plurality of coils associated with the second permeable magnetic member; wherein the first permeable magnetic member is located in the first pocket, the second permeable magnetic member is located in the second pocket, and the conductive member is located in the third pocket; wherein the field shaping assembly is configured to selectively shape a magnetic field generated with the first coil set and the second coil set.

2. The field shaping assembly of claim 1, wherein, the first surface area is greater than a combined surface area of the second surface area and the third surface area.

3. The field shaping assembly of claim 1, wherein, further comprising: a spacing member interposed between at least two of the conductive member, the first permeable magnetic member, and the second permeable magnetic member.

4. The field shaping assembly of claim 1, wherein, a periphery of the second permeable magnetic member is greater than a periphery of the conductive member, and the second permeable magnetic member encounters at least a portion of a magnetic field generated by the first coil set.

5. The field shaping assembly of claim 1, wherein, the first coil set and the second coil set combine with the conductive member, the first permeable magnetic member, and the second permeable magnetic member to form a distinct field.

6. A field shaping assembly as claimed in claim 5, wherein the field shaping assembly is configured to form a distinct field comprising a first vector of a first component of an emitted magnetic field, the first vector being different from a second vector of a second component of the emitted magnetic field.

7. A field shaping assembly as claimed in claim 6, wherein the first component is a first component in time, and the second component is a second component in time.

8. The field shaping assembly of claim 1, wherein, the first permeable magnetic member has an irregular periphery.

9. The field shaping assembly of claim 1, wherein, the first permeable magnetic member comprises a plurality of the first permeable magnetic members; wherein the conductive member is a single member; and wherein the second permeable magnetic member is a single member.

10. The field shaping assembly of claim 1, wherein, the first permeable magnetic member comprises a plurality of the first permeable magnetic members; wherein the conductive member comprises a plurality of the conductive members; and wherein the second permeable magnetic member is a single member.

11. A field shaping assembly comprising: a conductive member having a first surface, the first surface having a first surface area; a first permeable magnetic member having a second surface, the second surface having a second surface area; a second permeable magnetic member having a third surface, the third surface having a third surface area; a structural member having a first set of coil retaining pockets and a second set of coil retaining pockets, a first coil set located in the first set of coil retaining pockets and having a first plurality of coils associated with the first permeable magnetic member; and a second coil set located in the second set of coil retaining pockets and having a second plurality of coils associated with the second permeable magnetic member; a second coil set positioned in the second set of coil retaining pockets and having a second plurality of coils associated with the second magnetic permeable member; wherein the first surface area is greater than a combined surface area of the second surface area and the third surface area, wherein the first coil set is positioned above the first magnetic permeable member and the second coil set is positioned above the second magnetic permeable member; wherein the first magnetic permeable member and the second magnetic permeable member are positioned above the electrically conductive member; wherein the field shaping assembly is configured to selectively shape a magnetic field generated with the first coil set and the second coil set.

12. The field shaping assembly of claim 11, wherein, the first magnetic permeable member and the second magnetic permeable member are positioned on a single side of the electrically conductive member.

13. The field shaping assembly of claim 11, wherein, the first magnetic permeable member and the second magnetic permeable member are positioned on a single side of the electrically conductive member.

14. The field shaping assembly of claim 11, wherein, at least one of the first magnetic permeable member or the second magnetic permeable member is irregularly shaped.

15. The field shaping assembly of claim 11, wherein, further comprising: a spacer member that is substantially inert to magnetic fields and electric currents, including substantially non-magnetic and non-electrically conductive; wherein the spacer member is positioned between the electrically conductive member and at least one of the first magnetic permeable member or the second magnetic permeable member.

16. The field shaping assembly of claim 15, wherein, the electrically conductive member has high electrical conductivity, wherein the high electrical conductivity includes at least ten times the electrical conductivity of the first magnetic permeable member and the second magnetic permeable member.

17. The field shaping assembly of claim 11, wherein: the structural member has a first structural member surface, wherein the first structural member surface includes: a first pocket having a first size, the first pocket configured to receive the first magnetic permeable member; a second pocket having a second size, the second pocket configured to receive the second magnetic permeable member; and a receiving area configured to receive the electrically conductive member; wherein the electrically conductive member is positioned to sandwich the first magnetic permeable member and the second magnetic permeable member between the electrically conductive member and the first structural member surface.

18. The field shaping assembly of claim 17, wherein, the structural member includes coil retaining pockets to retain coils relative to the first magnetic permeable member.

19. The field shaping assembly of claim 18, wherein, the coil retaining pockets are positioned closer to an edge of the first magnetic permeable member than to a center of the first magnetic permeable member.

20. The field shaping assembly of claim 19, wherein, the coil retaining pockets include a plurality of coil retaining pockets positioned substantially asymmetrically relative to a center of the first magnetic permeable member.

21. A system having a localizer, the system comprising: an array of transmit coils including at least one coil of electrically conductive material operable to generate a transmit magnetic field; the field shaping assembly of claim 1 or 11, the field shaping assembly comprising: an electrically conductive member having a first surface having a first surface area; and a first magnetic permeable member having a second surface having a second surface area; wherein the field shaping assembly and the array of transmit coils cooperate to generate a selectively different field.

22. The system of claim 21, wherein, The transmitted magnetic field induces a current in the electrically conductive member to generate an induced magnetic field; wherein the current flows substantially around the first magnetic permeable member in the electrically conductive member.

23. The system of claim 22, wherein, A first vector of a first component of the transmitted magnetic field is different relative to a second vector of a second component of the induced magnetic field.

24. The system of claim 23, wherein, The first component and the second component are temporal.

25. The system of claim 21, wherein, The field shaping assembly further comprises: a second magnetic permeable member having a third surface with a third surface area; wherein the electrically conductive member is positioned between the first magnetic permeable member and the second magnetic permeable member.

26. The system of claim 21, wherein, The field shaping assembly further comprises: a second magnetic permeable member having a third surface with a third surface area; wherein the first surface area is greater than a combined surface area of the second surface area and the third surface area; wherein both the first magnetic permeable member and the second magnetic permeable member are positioned on a single side of the electrically conductive member.

27. The system of claim 26, wherein, The first magnetic permeable member and the second magnetic permeable member are spaced apart on the single side of the electrically conductive member.

28. The system of claim 23, wherein, Further comprising: a tracking device configured to sense the transmitted magnetic field and the induced magnetic field; and a processor configured to execute instructions to determine a position of the tracking device based on the sensed transmitted magnetic field and the induced magnetic field.

29. The system of claim 28, wherein, The difference in the first vector and the second vector allows for accurate navigation of the tracking device in a navigation volume defined by at least a portion of the transmitted magnetic field and the induced magnetic field.

30. The system of claim 21, wherein, The at least one coil is substantially planar relative to at least one of the first magnetic permeable member or the second magnetic permeable member.

31. The system of claim 30, wherein, The at least one coil is configured to induce a current in the electrically conductive member.

32. The system of claim 31, wherein, The induced current substantially circulates around at least one of the first magnetic permeable member or the second magnetic permeable member in the electrically conductive member.

33. The system of claim 21, wherein, Further comprising: a processor system configured to receive signals from a tracking device based on the selectively different fields sensed to determine a position of the tracking device within a navigation volume.

34. The system of claim 33, wherein, Further comprising: a display device to display the determined position of the tracking device.

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