Magnetic shape sensing using a local source

Abstract

Described herein are methods and apparatuses for shape sensing using local reference magnetic field generators and magnetic sensors that may be arranged in a line along a length of a flexible member. In general, these methods may use a plurality of magnetic emitters (e.g., coils and / or permanent magnet emitters) with a plurality of magnetic receivers (e.g., analog or digital magnetometers) arranged in a line. Local emitting of a magnetic field from each of the plurality of magnetic emitters may be differentially sensed by each of the magnetic receivers and this data may be used to uniquely identify the shape of the flexible member on which the emitters and detectors are located. Unlike traditional magnetic position and / or shape sensing, both the sensor and the emitter are moving with the flexible member.

Description

MAGNETIC SHAPE SENSING USING A LOCAL SOURCECLAIM OF PRIORITY

[0001] This patent application claims priority to U.S. provisional patent application no. 63 / 729,944, , titled “MAGNETIC SHAPE SENSING USING A LOCAL SOURCE,” and filed December 9, 2024, which is herein incorporated by reference in its entirety.BACKGROUND

[0002] Sensing the shape of a remotely operated device, such as a medical robot, may be critically important for controlling and operating the device, particularly in conditions in which the user may not be able to directly see the device. Magnetic shape sensing (MSS) is one technique that may be used for shape sensing. Traditional MSS involves embedding magnetic sensors or materials within a flexible medical instrument, allowing real-time tracking of their shape and position inside the body in combination with an external source of a magnetic field. This capability has proven critical important for minimally invasive procedures, where traditional imaging methods often struggle to provide sufficient detail or continuous monitoring of tools within complex anatomical structures. MSS can offer accurate, continuous, and radiation-free tracking, significantly enhancing the precision and safety of robotic-assisted interventions.

[0003] However, implementing this traditional MSS in medical robotics comes with several technical challenges. Magnetic fields are susceptible to interference from surrounding metallic objects, other magnetic sources, and even the body itself, which can distort sensor readings. Developing robust algorithms to mitigate these distortions and accurately reconstruct the shape of flexible instruments is a complex problem requiring advanced computational techniques. Additionally, integrating MSS into existing medical robotic systems demands seamless communication between the sensors, control systems, and user interfaces. These systems must operate with high reliability and speed, as even minor delays or inaccuracies could compromise patient outcomes. Finally, traditional systems require a rather large external magnetic field source, which may be positioned near to the patient, taking up valuable space in the operating theater and complicating movements around the patient.

[0004] Solutions to these challenges are needed to improve medical procedures. The methods and apparatuses described herein may reduce or eliminate the need for external fields, as well as improving the reliability and accuracy of shape sensing.- 1 -SG Docket No.: 13668-749.600SUMMARY OF THE DISCLOSURE

[0005] Described herein are methods and apparatuses (e.g., devices, systems, etc.) for performing magnetic shapes sensing using one more (e.g., an array) or local magnetic-field sources (e.g., emitters) and a plurality of magnetic field sensors (e.g., magnetometers). In particular, these methods and apparatuses may be arranged in a linear configuration along the lengths of a flexible member (e.g., catheter, overtube, etc. including in particular a scope, such as an endoscope). In some examples, these methods and apparatuses may include placing the magnetic field sensors at fixed locations / distances (e.g. in some cases at flexures) along all or a region of a length of the flexible member, along with one or more magnetic source emitters, and sensing the position of the magnetic field sensor relative to one or more of the emitters.

[0006] Thus, the apparatuses and methods described herein may include an array (e.g., a linear array) intermixing emitters (magnetic field sources) and a plurality of detectors (e.g. magnetic field sensors, or magnetometers) arranged along a length of an elongate flexible member, such as a steerable distal end region of the flexible member. The elongate flexible member may transmit the sensed magnetic field from each of the detectors to a controller that may (in real or near-real time) determine the relative position of the magnet field sensor(s), and therefore the shape of the elongate member.

[0007] In operation these methods and apparatuses may determine a relative position of the region of the elongate flexible member relative to the local source(s) of magnetic fields and / or relative to adjacent magnetic sensors and may therefore determine the shape of the elongate flexible member. Note that these apparatuses do not need to determine the absolute position in space, but instead, just relative shape of the region of the apparatus having the sensors.

[0008] For example, described herein are apparatuses comprising: an elongate body; a plurality of magnetic field sources extending along a least a portion of the elongate body, wherein each magnetic field source comprises a first emitter configured to emit a magnetic field in a first orientation and a second emitter configured to emit a magnetic field in a second orientation that is at an angle to the first magnetic field; a plurality of magnetic field sensors between each magnetic field sources at different longitudinal positions along the length of the at least the portion of the elongate body; and a processor configured to determine a shape of the at least the portion of the elongate body based a detected local magnetic field emitted by the one or more a magnetic field detectors and sensed by the one or more of the magnetic field source.- 2 -SG Docket No.: 13668-749.600

[0009] For example, each magnetic field source may further comprise a second emitter configured to emit a magnetic field in a second orientation that is at an angle to the first magnetic field. In any of these apparatuses and methods, the first emitter and the second emitter may be substantially orthogonal. In any of these apparatuses and methods, the first emitter may comprise a plurality of coils. Any of these apparatuses may include a controller configured to cause a pulsed energy to be delivered having a distinct frequency to each emitter of the plurality of magnetic field sources. The one or more processors may be part of the controller.

[0010] The plurality of magnetic field sensors may comprise a plurality of magnetometers. In general, the elongate body may comprise a catheter. In any of these apparatuses and methods the elongate body may comprise an endoscope. In any of these apparatuses and methods at least a portion of the elongate body comprises a steerable distal end region.

[0011] In any of these apparatuses and methods the one or more processors may be configured to compensate for background magnetic interference by subtracting a coil-off sensor reading from a coil-on sensor reading to isolate a locally generated magnetic field associated with an individual magnetic field source. Each magnetic field source may be driven at a distinct modulation frequency and the one or more processors isolates sensor signals using narrow-band filtering at the respective drive frequency to reduce cross-talk among adjacent magnetic field sources.

[0012] In any of these apparatuses and methods the first emitter may comprise a coil oriented substantially parallel to a longitudinal axis of the elongate body and the second emitter comprises a coil oriented substantially perpendicular to the longitudinal axis. The plurality of magnetic field sensors may include sensors positioned off-axis relative to a midline of the elongate body at a defined radial offset to ensure multiple transverse axes of each magnetometer exhibit bend-dependent signal variation. The magnetic field sources and the magnetic field sensors may be arranged in repeating units along the elongate body, each repeating unit comprising one magnetic field source flanked by a pair of magnetic field sensors longitudinally spaced from the magnetic field source.

[0013] Any of these apparatuses may include a flexible electronics substrate wrapped around or embedded within a wall of the elongate body, the flexible electronics substrate carrying interconnects that couple the magnetic field sources and the magnetic field sensors to one or more controllers.

[0014] The one or more processors may be configured to determine a local curvature of the elongate body using a Biot-Savart model that maps magnetometer readings to curvature- 3 -SG Docket No.: 13668-749.600as a function of sensor spacing from a corresponding magnetic field source and further refines the curvature using a calibration table generated from empirical measurements. The magnetic field sensors are connected via a plurality of discrete serial buses selected from FC, FC, or SPI, each bus addressing a different sensor to increase sampling throughput and reduce addressing conflicts.

[0015] Any of these apparatuses may include a plurality of secondary microcontrollers disposed along the elongate body, each secondary microcontroller being configured to compute local curvature from its associated sensor data and transmit curvature results to a primary controller for shape reconstruction of the elongate body.

[0016] For example, an apparatus as described herein may include: an elongate body; a plurality of magnetic field sources extending along a least a portion of the elongate body, wherein each magnetic field source comprises a first emitter configured to emit a magnetic field in a first orientation and a second emitter configured to emit a magnetic field in a second orientation that is at an angle to the first magnetic field; a plurality of magnetic field sensors between each magnetic field sources at different longitudinal positions along the length of the at least the portion of the elongate body; and one or more processors configured to determine a shape of the at least the portion of the elongate body based on a relative change in local position or bend between the magnetic field sources and the magnetic field detectors.

[0017] An apparatus may include: an elongate body; a plurality of magnetic field sources and a plurality of magnetic field sensors arranged helically about a circumference of the elongate body; a controller configured to drive the magnetic field sources in a time-multiplexed manner to mitigate cross-talk; and one or more processors configured to reconstruct a three-dimensional shape of at least a portion of the elongate body based on sensed local magnetic fields from multiple radial positions.

[0018] Also described herein are methods, including methods of sensing the shape of an elongate member. For example, a method of determining a shape of an elongate body may include: generating, by a controller, a magnetic field from a plurality of magnetic field sources disposed along at least a portion of the elongate body; sensing, by a plurality of magnetic field sensors disposed along the elongate body, local magnetic field data associated with the magnetic field sources; isolating, by the controller, signals corresponding to individual magnetic field sources using time-domain multiplexing and / or frequency-domain filtering; compensating for background magnetic interference by subtracting a sensor reading obtained in a de-energized state from a sensor reading obtained in an energized state; and determining, by a processor, a shape of the at least the portion of the elongate body based on the compensated sensor readings.- 4 -SG Docket No.: 13668-749.600

[0019] Any of these methods may include driving each magnetic field source at a distinct frequency and applying narrow-band filtering to isolate signals from adjacent magnetic field sources. Determining the shape may include applying a Biot-Savart model or a dipole approximation to map magnetometer readings to curvature of the elongate body.

[0020] Any of these methods may include computing local curvature at a plurality of longitudinal positions and reconstructing a three-dimensional shape of the elongate body from the local curvature. The magnetic field sources may be pulsed and any of these methods may include subtracting coil-off readings from coil-on readings to remove external magnetic influences. In some cases the magnetic field sensors may be positioned off-axis or in a helical pattern around a circumference of the elongate body to improve sensitivity to multi-plane bending.

[0021] Any of these methods may include transmitting sensor data to a plurality of secondary microcontrollers configured to compute local curvature and sending curvature results to a primary controller for shape reconstruction. The processor apply calibration using a look-up table generated from empirical measurements to refine curvature estimation.

[0022] Any of these methods may include outputting the bend information, including transmitting storing and / or displaying. For example, any of these methods may include displaying, on an output interface, a visual representation of the reconstructed shape and one or more bend metrics derived from the curvature.

[0023] The magnetic field sources may comprise coils oriented in different directions, including at least one coil substantially parallel to a longitudinal axis and at least one coil substantially perpendicular to the longitudinal axis.

[0024] For example, any of these methods may be methods of sensing shape comprising: generating, by a controller, a magnetic field from a plurality of magnetic field sources disposed along at least a portion of the elongate body; sensing, by a plurality of magnetic field sensors disposed along the elongate body, local magnetic field data associated with the magnetic field sources; and determining, by a processor, a shape of the at least the portion of the elongate body based on the local magnetic field data.

[0025] All of the methods and apparatuses described herein, in any combination, are herein contemplated and can be used to achieve the benefits as described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] A better understanding of the features and advantages of the methods and apparatuses described herein will be obtained by reference to the following detailed- 5 -SG Docket No.: 13668-749.600description that sets forth illustrative embodiments, and the accompanying drawings of which:

[0027] FIG. 1 A schematically illustrates one example of an apparatus for sensing the shape of an elongate member that includes at least one local magnetic source and a plurality of shape sensors arranged along a length of the elongate member.

[0028] FIG. IB schematically illustrates an apparatus for sensing shape of an elongate member including an output display showing the sensed magnetic field.

[0029] FIG. 2A schematically illustrate a portion of an elongate body including a plurality of magnetometers offset by 5mm laterally from the midline of the elongate body and one or more magnetic field generators (e.g., emitters) including a coil positioned perpendicular to the scope axis. FIG. 2B are graphs of the x- and y-axis readings for the first magnetometer shown estimated using a Biot-Savart model to map the expected magnetometry reading at a particular position for a particular curvature of the elongate member (e.g., endoscope).

[0030] FIGS. 2C-2D illustrate an example of a portion of an elongate body including a pair of magnetometers (FIG. 2D) and examples of graphs of x-axis and y-axis values for bend angles as estimated by Biot-Savart at different magnetometer values in this configuration. In FIGS. 2C-2D the magnetic field source includes coils that are arranged in parallel with the long axis of the elongate member.

[0031] FIGS. 2E-2F illustrate an example of a portion of an elongate body including a pair of magnetometers (FIG. 2E) and examples of graphs of x-axis and y-axis values for bend angles as estimated by Biot-Savart at different magnetometer values in this configuration. In FIGS. 2E-2F the magnetic field source includes coils that are arranged perpendicular with the long axis of the elongate member.

[0032] FIGS. 3A and 3B illustrate an experimental setup including an elongate flexible device including a plurality of shape sensing used to illustrate the general concept.

[0033] FIG. 3C shows data illustrating raw shape sensing data for the setup shown in FIGS. 3 A and 3B.

[0034] FIGS. 4A-4B illustrate net sensor data for the results shown in FIG. 3C for the distal sensor (FIG. 4 A) and the proximal sensor (FIG. 4B).

[0035] FIGS. 5A-5B illustrate net sensor data for the results shown in FIG. 3C show relative angle of the joint between segment A and B (FIG. 4 A) and the end of segment B (FIG. 4B) in FIGS. 3A-3B.

[0036] FIGS. 6A-6E illustrate examples of magnetic sources (emitters, e.g., coils) that may be used with any of the apparatuses described herein.- 6 -SG Docket No.: 13668-749.600

[0037] FIG. 7 is an example of a magnetometer that may be used with the methods and apparatuses described herein.

[0038] FIGS. 8A-8C illustrate variations of apparatuses including a line of magnetic emitters and sensors along a length of a flexible member.

[0039] FIG. 9 illustrates one example of an apparatus as described herein.

[0040] FIGS. 10A and 10B illustrated examples of architectures for apparatuses as described herein. FIG. 10A shows an example of an apparatus including a plurality of sensors that are connected via a bus within the endoscope body. FIG. 10B shows an alternative configuration in which each sensor is also connected to a local microcontroller (“secondary MCU”) to assist in calculating bend based on sensed local magnetic field.DETAILED DESCRIPTION

[0041] Described herein are methods and apparatuses for shape sensing using local reference magnetic field generators and magnetic sensors that may be arranged in a line along a length of a flexible member. In general, these methods may use a plurality of magnetic emitters (e.g., coils and / or permanent magnet emitters) with a plurality of magnetic receivers (e.g., analog or digital magnetometers) arranged in a line. Local emitting of a magnetic field from each of the plurality of magnetic emitters may be differentially sensed by each of the magnetic receivers and this data may be used to uniquely identify the shape of the flexible member on which the emitters and detectors are located. Unlike traditional magnetic position and / or shape sensing, both the sensor and the emitter are moving with the flexible member. In some cases, the spacing between the emitters may be known and used to help identify relative position and / or shape of the flexible member to which the shape emitters and / or sensors are attached. In some cases the emitters (transmitting coils) may be driven at different frequencies.

[0042] Described herein are magnetometer-based shape sensing. In general, a variety of different sensors may be used as a magnetometer capable of detecting internally generated magnetic fields that can detect the shape of an endoscope. Any magnetic sensor may be used, including but not limited to a digital magnetometer. For example, an analog coil may be used. A magnetic source may include a single emitter (e.g., coil emitter) or a plurality of emitters, including sets of two or, in some cases, three orthogonal (or near-orthogonal) emitters. For example, emitter may include two or more non-orthogonal emitters.

[0043] The methods and apparatuses described herein may locally generate a magnetic field from a position on the elongate member (e.g., catheter, endoscope, tube, etc.) from a fixed position on the length of the elongate member and sense the resulting magnetic field - 7 -SG Docket No.: 13668-749.600from one (or preferably more than one) position(s) along the length of the elongate member. Any appropriate magnetic field may be used, including alternating, static and / or pulsed. Alternating magnetic fields may be generated by driving an electromagnet with an alternating electric field, or by physically rotating a magnetic field. Alternating magnetic fields may be particularly useful in magnetic shape sensing, since temporal data can be used to identify specific signals within noisy data. This may include instance where there are many magnetic fields, in which frequency data allows a sensor to identify the field change resulting from a specific alternating field generator. Alternating fields may also be useful for detecting signals below the noise floor. Noise is typically random, so signals at defined frequencies can be extracted. Generating an alternating magnetic field may involve rotating a permanent magnet or need multiple generator coils driven by alternating current.

[0044] Static magnetic fields may be implemented using a permanent magnet or an electromagnet driven with direct current. Such fields may be vulnerable to interference as it may be difficult to separate signals from field generator and interring material (e.g., residual magnetic fields). In use, it may be desirable to use a relatively large, generated field amplitude for a static magnetic field.

[0045] Pulsed magnetic fields (e.g., pulsed DC) may be implemented with an electromagnet. The apparatus may changes the state of the magnet field (e.g. off to on). Comparison of sensor readings in different states may allow the system to remove interfering magnetic fields from the signal. Position and location data can be calculated independently from frequency, as the sensor readings are taken in at least two states. In general, a system using a pulsed magnetic field may function independently of when the fields are switched on and off. The time spent on and the time spent off may both be arbitrary (through configured to provide enough time for the sensor to get a reading). Measurements may be taken going from an on-to-off state and / or from an off-to-on state. An individual measurement (e.g., magnetometer reading with background disturbances removed) does not require any cycling of the field state. A single measurement may be made without the field needing to be switched back to its starting state. Any of these methods and apparatuses may use more than two different DC states in an arbitrary order, with coil driven forwards, off, and backwards (for example). In use, a ‘global’ field over the whole measured area, of roughly constant magnitude and direction, e.g., pointing to the right and slightly down, may indicate the earth’s magnetic field. The coil-off reading may be subtracted from the signal which may remove the external influences on the magnetic field leaving the field shape due to the magnetic coil.- 8 -SG Docket No.: 13668-749.600

[0046] As discussed above, any appropriate magnetic field sensor (e.g., magnetometer) may be used including digital magnetometers, analogue magnetometers, etc. Digital magnetometers may include automatic calibration and temperature sensing. Analogue magnetometers may have decreased latency and reduced capacitance challenges on a digital bus.

[0047] Examples of digital magnetometers may include MMC5603NJ, MMC5633NJL (e.g., 6.25 nT / LSB resolution, ±3 mT range), LIS2MDLTR and / or IIS2MDCTR (150 nT / LSB resolution, ±5 mT range), or the like.

[0048] The sensors may be arranged along the length of the elongate member and may be oriented in any appropriate manner (including orthogonally to each other). Sensor may be connected to a controller (and / or to each other in some configurations) using any appropriate connector, e.g., Inter-Integrated Circuit (I2C) with multiplexer, discrete Inter-Integrated Circuit (I2C) busses, which may individually connect to each sensor, Inter-Integrated Circuit (I2C) with gating, Improved Inter-Integrated Circuit (13 C), serial peripheral interface (SPI), etc. For example, discrete I2C busses may directly connect to each sensor. For example, each sensor may communicate using its own serial bus cable. For example, 60 or more coax cables may be used, addressing 60 or more sensors, (e.g., providing a bundled cable diameter in some examples of ~1.4mm with 80% packing density). The configuration using discrete, e.g., I2C busses, may be easier to address with a large numbers of sensors (multiple sensors with the same address can be used), and may allow communication with multiple sensors simultaneously, speeding up data rate.

[0049] The elongate member may include and / or may be connected (via one or more connectors) to a controller. In some examples distributed computation may be used. For example, local curvature could be computed with a dedicated microcontroller (MCU) at each sensor. This may allow processing ‘on the edge’ which reduces the data transmission requirement down the endoscope, potentially improving refresh rate of the algorithm. For example, the controller may include one or more processors and may be performed off of the elongate member (e.g., off of the endoscope body), e.g., in a primary microcontroller that receives input from the magnetic sensors and / or magnet field generator(s). Alternatively or additionally, the computation may be distributed between the elongate body (e.g., endoscope) and / or along the elongate body and an external (e.g., off of the endoscope) controller. A primary controller (e.g., microcontroller) may be located off of the elongate body, e.g., in a robotic device of other manipulator) or other structure the may connect to the elongate body, and one or more (a plurality of) secondary controllers (e.g., microcontrollers) may be present on the elongate body and connected via one or more connectors.- 9 -SG Docket No.: 13668-749.600

[0050] In a static and well-characterized magnetic field, each point in space is associated with a unique magnetic field vector, defined by both magnitude and direction. Therefore, a magnetometer’s position and orientation can be inferred by comparing the measured local field vector (i.e. the sensor reading) to the spatial model of the magnetic field. Magnetic field orientation at a given point remains constant for a given field generator, irrespective of amplitude. Regardless of current passing through a generator coil the orientation of the sensor reading remains constant. The position of a sensor in a magnetic field cannot be uniquely determined using only the field's orientation, as not all positions have a unique orientation. By including endoscope mechanics (e.g. through a constant curvature assumption), it is possible to constrain potential endoscope position to a well-defined region or surface (e.g., dome). Points on this region or surface (e.g., dome) will have unique local magnetic field orientations at all positions, allowing the position and orientation of the endoscope to be calculated without using the magnitude of the field generator. Without knowing the source amplitude, information about the system’s potential error and sensitivity may be lost. Thus, in any of these methods and apparatuses, endoscope mechanics can be used to define the potential positions of the endoscope, each of which may have a unique orientation.

[0051] In general, described herein are methods and apparatuses for detecting the shape of an elongate member, such as (but not limited to) an endoscope. These methods and apparatuses may use one or more local magnetic sources (on the elongate member) and a plurality of magnetometers on the same elongate member to detect the internally generated magnetic fields and use the detected fields to determine the shape of the elongate member in real time, with a high degree of accuracy.

[0052] In FIG. 1 A, the schematic illustrates a catheter 105 including at least on magnetic field source 101, shown as a plurality of wrapped coils, which may be wrapped transversely around the catheter, may be flattened against the catheter, etc. The magnetic field source may be attached to and / or embedded within a wall of the catheter. In some case the magnetic field source may be coupled to a substrate, e.g., a strip or sheet of material, such a flexible electronics substrate (e.g., flex circuit) that may be incorporated into and / or wrapped around the elongate member. For example the magnetic field sources and a plurality of magnetic sensors may be arranged on a strip of substrate (e.g., flex circuit) including connectors (e.g., power line(s), sensing line(s), etc.) and wrapped around the elongate member of at least a portion of the length of the apparatus and / or incorporated into the wall of the flexible member, such as a catheter and / or scope.- 10 -SG Docket No.: 13668-749.600

[0053] The flexible elongate member 105 may be any appropriate catheter and / or a scope. Any appropriate scope may include the array of local magnetic field source (emitters) and magnetic sensors described herein. In particular, these methods and apparatuses may be configured as, or for use with a scope such as colonoscopes, arthroscopes, bronchoscopes, cystoscopes, hysteroscope, enteroscopes, esophagogastroduodenoscopes, hysteroscopes, neuroendoscopes, sinuscopes, laparoscopes, laryngoscopes, mediastinoscopes, sigmoidoscopes, nasopharyngoscopes, thoracoscopes, ureteroscopes, etc.

[0054] In particular, these methods and apparatuses may be used with an elongate member that may transition between a rigidi configuration and a flexible configuration, including particular an apparatus that may transition by the application of pressure. Examples of such apparatuses may be found in: U.S. patent application no. 16631473, titled " DYNAMICALLY RIGIDIZING OVERTUBE,” and filed on 7 / 19 / 2018; U.S. patent application no. 17152706, titled " DYNAMICALLY RIGIDIZING COMPOSITE MEDICAL STRUCTURES,” and filed on 1 / 19 / 2021 (now U.S. 11135398); U.S. patent application no. 17493785, titled " DYNAMICALLY RIGIDIZING COMPOSITE MEDICAL STRUCTURES,” and filed on 10 / 4 / 2021 (now U.S. 11478608); U.S. patent application no. 17903879, titled " RIGIDIZING DEVICES,” and filed on 9 / 6 / 2022 (now U.S. 11554248); U.S. patent application no. 17902770, titled " NESTED RIGIDIZING DEVICES,” and filed on 9 / 2 / 2022 (now U.S. 11724065); U.S. patent application no. 17940906, titled " EXTERNAL WORKING CHANNELS,” and filed on 9 / 8 / 2022 (now U.S. 11793392); U.S. patent application no. 17604203, titled " DYNAMICALLY RIGIDIZING COMPOSITE MEDICAL STRUCTURES,” and filed on 1 / 16 / 2020; U.S. patent application no. 17995294, titled " LAYERED WALLS FOR RIGIDIZING DEVICES,” and filed on 3 / 29 / 2021 (now U.S. 11744443); U.S. patent application no. 18000062, titled " RIGIDIZING DEVICES,” and filed on 5 / 26 / 2021; U.S. patent application no. 18044027, titled " DYNAMICALLY RIGIDIZING GUIDERAIL AND METHODS OF USE,” and filed on 9 / 3 / 2021; U.S. patent application no. 18263517, titled " DEVICES AND METHODS TO PREVENT INADVERTENT MOTION OF DYNAMICALLY RIGIDIZING APPARATUSES,” and filed on 1 / 31 / 2022 (now U.S. 12121677); U.S. patent application no. 18550123, titled " CONTROL OF ROBOTIC DYNAMICALLY RIGIDIZING COMPOSITE MEDICAL STRUCTURES,” and filed on 3 / 10 / 2022; U.S. patent application no. 18723414, titled " METHODS AND APPARATUSES FOR REDUCING CURVATURE OF A COLON,” and filed on 12 / 22 / 2022; U.S. patent application no. 18727032, titled " RECONFIGURABLE RIGIDIZING STRUCTURES,” and filed on 1 / 4 / 2023; U.S. patent application no. 18837186, titled " DYNAMICALLY RIGIDIZING COMPOSITE MEDICAL STRUCTURES,” and- 11 -SG Docket No.: 13668-749.600filed on 2 / 8 / 2023; U.S. patent application no. 18851053, titled " METHODS AND APPARATUSES FOR NAVIGATING USING A PAIR OF RIGIDIZING DEVICES,” and filed on 3 / 27 / 2023; U.S. patent application no. 18325979, titled " APPARATUSES AND METHODS FOR DETERMINING IF AN ENDOSCOPE IS CONTAMINATED,” and filed on 5 / 30 / 2023 (now U.S. 11937778); and U.S. patent application no. 18582634, titled " METHODS OF ATTACHING A RIGIDIZING SHEATH TO AN ENDOSCOPE,” and filed on 2 / 20 / 2024 (now U.S. 12102289), each of which is herein incorporated by reference in its entirety.

[0055] In FIG. 1 A, a simplified setup is shown including a pair of magnetic sensors 103 that are spaced apart from each other and are spaced relative to a local magnetic field source 101 (e.g., a plurality of transverse coils that may emit a field 107 that is aligned with the coils in a predictable manner. In this example the wires powering the magnetic source 101 and / or reading off of the sensors 105 may extend in a helical wrapping proximally down the length of the elongate member (e.g., catheter 105).

[0056] In this example the distance between each of the adjacent sensors 103, 103’ (and the magnetic field source and immediately adjacent sensors) is relatively constant, though in some examples the separation between the two may be varying.

[0057] Each magnetic field source 101 may comprise a pair of sets of coils for emitting fields in different directions, at a known angle relative to each other. In particular, a magnetic field source may include a set of two or more emitters (sets of coils) that may optionally (but in some cases, preferentially) be configured as orthogonal.

[0058] The magnetic sensors and / or magnetic field source may be any appropriate length apart, such as between 2 mm and 50 mm apart (e.g., between 3 mm and 40 mm, between 3mm and 35 mm, between 3 mm and 30 mm, between 3 mm and 25 mm, between 3 mm and 20 mm, between 3 mm and 15 mm, between 3 mm and 10 mm, etc.) along the length of the flexible member.

[0059] FIG. IB schematically illustrates another example of an apparatus similar to that shown in FIG. 1 A, including a magnetic field source 101 on the elongate body and a plurality of magnetometers 103 arranged along the elongate body. The shape is determined by a controller (not shown) or controllers (not shown) coupled to the magnetic source and magnetometers that can apply the magnetic field and interpret the magnetometer data to determine the shape of the elongate member 105. FIG. IB also shows an example of an output 109, configured as a display screen, showing the determined shape.

[0060] In the examples described herein, the magnetometer (sensor) may achieve a resolution of greater than 6.25nT / LSB with 200nT rms noise (or better). The sensors (e.g.,- 12 -SG Docket No.: 13668-749.600digital sensors) can be addressed using common serial interfaces (e.g., I2C, 13 C, SPI), and bend angle errors on of 1° or less may be sensed along a 1-2 meter (e.g., 1.4-1.6 m) with sensors spaced between 40 mm away from their respective field generator(s). In any of these examples, magnetic field generation may use a field generator with approximately 30 ampturns, based on a coil of less than 25 mm (e.g., approximately 10 mm-20mm). For example, endoscope devices had a coils of diameter ~12.7mm or less. Both alternating and pulsed magnetic fields were used and may allow removal of interference from external magnetic sources and magnetically permeable material. Field (coil) orientation may be adjusted to shape the field and increase contrast, thereby improving sensitivity. The results described herein illustrate a high degree of performance in shape reconstruction.

[0061] The methods and apparatuses may estimate shape of the elongate member on which the magnetic field generator(s) and magnetic field sensor(s) (e.g., magnetometers) are positioned using information about the elongate member and applying a Biot-Savart pose estimation. In some examples this Biot-Savart pose estimation may be corrected or modified by using corrections, including using one or more calibration and look-up tables to correct for potential errors in pose estimation.

[0062] As mentioned, in some cases a Biot-Savart model technique may be used to estimate shape from the magnetometer data. For example a Biot-Savart model may allow the apparatus or method to estimate the curvature of segments of the elongate member (e.g., endoscope) based on the readings of magnetometer arranged over the length of the elongate member. In some cases, since the noise associated with magnetometers is well defined in the sensor’s data sheet (e.g., 200nT), it is possible to estimate the error in curvature using the Biot-Savart model. For example, the magnetometer reading used to estimate the shape may be shifted (e.g., for a straight endoscope was shifted by the defined noise, such as 200 nT). The expected curvature with the shifted magnetometer reading may provide an approximation error in a single segment of the endoscope.

[0063] For example, a Biot-Savart model may be used to map the expected magnetometer reading to the curvature of an endoscope, as shown in FIGS. 2A-2C. In FIG. 2B, the graphs show the estimated curvature for an apparatus configured as shown in FIG. 2A at a variety of expected measurements for the magnetometer. In FIG. 2B two curves are shown on each of the X-axis and Y-axis readings; the first measurement corresponds to a sensor that is 80 mm along the endoscope from the magnetic field generator; the second corresponds to a sensor that is 40 mm along the scope length from the magnetic field generator. Thus, these estimates may be used to predict the curvature and / or position of the elongate member.- 13 -SG Docket No.: 13668-749.600

[0064] Other techniques may be used in addition to or instead of Biot-Savart modeling to approximate curvature / position of an elongate member based on magnetometer reading. For example, in some case dipole field model (e.g., dipole approximation) may be used. As described above, the applied field may be a pulse filed and / or an alternating field. An alternating and / or pulsed field may allow background magnetic fields to be filtered, therefore reducing interference from Earth’s magnetic field or nearby permanent magnets. Pulsed and alternating fields were particularly effective in reducing noise. Although it was believed that both techniques would still see distortion from permeable materials, including the endoscope, in practice this effect is small in most cases. The field generator and signal processing algorithms may be configured to reduce these effects. Pulsed and alternating fields may also offer the ability to tailor field characteristics and operate in a window less susceptible to noise.

[0065] When using pulsed field measurements, coil-off readings may be subtracted from coil-on readings. This may require only a single change of coil state. Nearby coils may be pulsed one at a time to eliminate cross-talk from adjacent coils. When using alternating field measurements, the coil may be driven by AC current, and the coil signal may be isolated via a narrow-band filter, using the coil drive frequency. Different coils may be run at different frequencies to eliminate cross-talk, including sampling nearby sensors simultaneously.

[0066] In general, the magnetic source (e.g., the magnetic field generator) may include one or more coils that may be oriented differently. For example, FIGS. 2C-2D show another example of a configuration in which (as shown in FIG. 2C) the sensor(s) may be arrange on a central axis of the elongate member (e.g., endoscope). FIG. 2D shows the predicted curvature based on different values for the sensed magnetic field from magnetometers at different distances from the magnetic field generator, in which the field generator includes coils that are parallel to the scope axis (e.g., “axial coils”). FIGS. 2E-2F show another arrangement of an apparatus as described herein, in which the magnetometers are arranged offset from the midline of the elongate body (e.g., catheter) and the coil is oriented perpendicular to the offset magnetometer (e.g., “perpendicular coils”). The coil geometry and orientation, as well as the sensor location, may impact pose estimation accuracy. In particular, a perpendicular coil may be preferred to achieve effective pose estimation.

[0067] Another example of a potential magnetic field generator having a coil is shown in FIG. 9. In this example the elongate body 905 is shown with a coil 905 wrapped around it. In general, coils could be implemented using, e.g., a wound magnet wire construction or a flex circuit. In some cases axial coils may be used for magnet wire construction and / or perpendicular coils could be manufactured as flat flex circuit and wrapped around endoscope.- 14 -SG Docket No.: 13668-749.600In the example shown in FIG. 9, a magnetometer 903 is also shown (additional sensors may be included as well) and this magnetometer position is rotated so that the sensor sits at 45 degrees radially offset from the coil axis to ensure both magnetometer axes that are perpendicular to the endoscope provide a signal that varies with bend angle.

[0068] FIGS. 3A-3B illustrate an example of a magnetic field source 101 coupled adjacently to a first magnetic field sensor 103 that it itself coupled adjacent to a second magnetic field sensor 103’. Additional magnetic field sources and sensors may be included, arranged in-line. FIG. 3 A shows the setup in which the magnetic field source and sensors are maximally separated from each other in a line. In FIG. 3B the sensors are moved as the shape bends. FIG. 3C shows the raw sensor data for the two magnetic field sensors and indicates the movements made (shown on the x axis); the sensed magnetic field (in uT) is shown on the y- axis.

[0069] The data collected in FIG. 3C shows that changes in relative position, e.g., relative to the magnetic field source, are detected and may reflect relative position changes. FIGS. 4A-4B show proximal (FIG. 4A) and distal (FIG. 4B) net sensor output. The relative location may be a function of the magnetic intensity. FIGS. 5A and 5B show estimated angle for the proximal sensor angle (FIG. 5A) and distal sensor angle (FIG. 5B).

[0070] In practice the magnetic field source may include orthogonal pairs of coils. Multiple windings may be used. In some cases the windings may be flat and may be wrapped around the wall of the elongate member or they may be transverse to the elongate member. FIGS. 6A-6E illustrate examples of magnetic field sources that may be used. In addition to coils, other magnetic sources may be used. FIG. 7 illustrates one example of a magnetometer (sensor) that may be used.

[0071] The field emitted by the magnetic field sources may be modulated (e.g., driven at a frequency or more complex modulation). Fields may be emitted from multiple different magnetic field sources and sensed by all or some of the detectors. In some cases the magnetic field sources may be multiplexed together. Processing may be performed in the time domain and / or in the frequency domain.

[0072] During fabrication the magnetic field sources and / or sensors may be embedded into the wall of the apparatus either directly or as part of a strip or layer. For example, the magnetic field sources and / or sensors may be positioned on a wire or flex circuit that is wrapped, e.g., helically, around the wall of the flexible apparatus.

[0073] FIGS. 8A-8C illustrate examples of different variations of apparatuses including a line of magnetic field sources 805 and sensors 807, 807’. Groups of magnetic field source(s) and sensors may be set up as repeating units 815, as shown in FIG. 8 A. In this example, each- 15 -SG Docket No.: 13668-749.600magnetic field source is flanked by a pair of sensors, which may provide easy detection of local bending relative to each magnetic field source and the adjacent sensor. FIG. 8B shows another example in which a larger number of sensors (e.g., 7 are shown, but this may be more or fewer) are adjacently arranged between magnetic field sources. The sensors and / or magnetic field sources may be positioned off-axis relative to the elongate member, as they may be located on a wall of the elongate member. In some cases, an example of which is shown in FIG. 8C, the magnetic field sources and / or sensors may be arranged in different radial locations around the perimeter of the catheter. In FIG. 8C the sensors are arranged in a helical pattern around the catheter.

[0074] In any of the methods and apparatuses described herein, the sensors (magnetometers), magnetic field generator(s) and processor(s) may be arranged so as to optimize performance, without impacting the relatively small footprint needed, and without significantly decreasing flexibility of the elongate member. In particular, the communication protocols and routing of the connections between these components may be arranged in a variety of ways, as illustrated in FIGS. 10A-10B. For example, in some configurations (as shown in FIG. 10A) the cross-sectional footprint may be minimized. In some cases this may include using a plurality of discrete I2C buses for each sensor, where each sensor is connected to its own I2C bus that is connected to its individual pair of cables in a micro-coax cable assembly. In any of these apparatuses the connectors may be bundled, e.g., managing the physical cabling by forming a bundle of micro-coax cables that may be routed through the endoscope. A connection may break out from the bundle to address each sensor. In some examples cable bundle may have a ~1.4 mm diameter or smaller and may be configured to reduce any added stiffness to the endoscope, e.g., by allowing relatively longitudinal movement, lubricating them, including slack, take-up regions, etc.

[0075] Cabling complexity may be reduced by including the use of SPI sensors connected by a shift register. In some examples discrete SPI buses may be used for each sensor, and each sensor may be connected to its own SPI bus that is connected to its individual pair of cables in a micro-coax cable assembly.

[0076] In FIG. 10B, local curvature could be computed with dedicated microcontroller (MCU) at each sensor, allowing distributed computation of the bend, as described above.

[0077] All publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. Furthermore, it should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts- 16 -SG Docket No.: 13668-749.600are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein and may be used to achieve the benefits described herein.

[0078] Any of the methods (including user interfaces) described herein may be implemented as software, hardware or firmware, and may be described as a non-transitory computer-readable storage medium storing a set of instructions capable of being executed by a processor (e.g., computer, tablet, smartphone, etc.), that when executed by the processor causes the processor to control perform any of the steps, including but not limited to: displaying, communicating with the user, analyzing, modifying parameters (including timing, frequency, intensity, etc.), determining, alerting, or the like. For example, any of the methods described herein may be performed, at least in part, by an apparatus including one or more processors having a memory storing a non-transitory computer-readable storage medium storing a set of instructions for the processes(s) of the method.

[0079] While various embodiments have been described and / or illustrated herein in the context of fully functional computing systems, one or more of these example embodiments may be distributed as a program product in a variety of forms, regardless of the particular type of computer-readable media used to actually carry out the distribution. The embodiments disclosed herein may also be implemented using software modules that perform certain tasks. These software modules may include script, batch, or other executable files that may be stored on a computer-readable storage medium or in a computing system. In some embodiments, these software modules may configure a computing system to perform one or more of the example embodiments disclosed herein.

[0080] As described herein, the computing devices and systems described and / or illustrated herein broadly represent any type or form of computing device or system capable of executing computer-readable instructions, such as those contained within the modules described herein. In their most basic configuration, these computing device(s) may each comprise at least one memory device and at least one physical processor.

[0081] The term “memory” or “memory device,” as used herein, generally represents any type or form of volatile or non-volatile storage device or medium capable of storing data and / or computer-readable instructions. In one example, a memory device may store, load, and / or maintain one or more of the modules described herein. Examples of memory devices comprise, without limitation, Random Access Memory (RAM), Read Only Memory (ROM), flash memory, Hard Disk Drives (HDDs), Solid-State Drives (SSDs), optical disk drives, caches, variations or combinations of one or more of the same, or any other suitable storage memory.- 17 -SG Docket No.: 13668-749.600

[0082] In addition, the term “processor” or “physical processor,” as used herein, generally refers to any type or form of hardware-implemented processing unit capable of interpreting and / or executing computer-readable instructions. In one example, a physical processor may access and / or modify one or more modules stored in the above-described memory device. Examples of physical processors comprise, without limitation, microprocessors, microcontrollers, Central Processing Units (CPUs), Field-Programmable Gate Arrays (FPGAs) that implement softcore processors, Application-Specific Integrated Circuits (ASICs), portions of one or more of the same, variations or combinations of one or more of the same, or any other suitable physical processor.

[0083] Although illustrated as separate elements, the method steps described and / or illustrated herein may represent portions of a single application. In addition, in some embodiments one or more of these steps may represent or correspond to one or more software applications or programs that, when executed by a computing device, may cause the computing device to perform one or more tasks, such as the method step.

[0084] In addition, one or more of the devices described herein may transform data, physical devices, and / or representations of physical devices from one form to another. Additionally or alternatively, one or more of the modules recited herein may transform a processor, volatile memory, non-volatile memory, and / or any other portion of a physical computing device from one form of computing device to another form of computing device by executing on the computing device, storing data on the computing device, and / or otherwise interacting with the computing device.

[0085] The term “computer-readable medium,” as used herein, generally refers to any form of device, carrier, or medium capable of storing or carrying computer-readable instructions. Examples of computer-readable media comprise, without limitation, transmission-type media, such as carrier waves, and non-transitory-type media, such as magnetic-storage media (e.g., hard disk drives, tape drives, and floppy disks), optical -storage media (e.g., Compact Disks (CDs), Digital Video Disks (DVDs), and BLU-RAY disks), electronic-storage media (e.g., solid-state drives and flash media), and other distribution systems.

[0086] A person of ordinary skill in the art will recognize that any process or method disclosed herein can be modified in many ways. The process parameters and sequence of the steps described and / or illustrated herein are given by way of example only and can be varied as desired. For example, while the steps illustrated and / or described herein may be shown or discussed in a particular order, these steps do not necessarily need to be performed in the order illustrated or discussed.- 18 -SG Docket No.: 13668-749.600

[0087] The various exemplary methods described and / or illustrated herein may also omit one or more of the steps described or illustrated herein or comprise additional steps in addition to those disclosed. Further, a step of any method as disclosed herein can be combined with any one or more steps of any other method as disclosed herein.

[0088] The processor as described herein can be configured to perform one or more steps of any method disclosed herein. Alternatively or in combination, the processor can be configured to combine one or more steps of one or more methods as disclosed herein.

[0089] When a feature or element is herein referred to as being "on" another feature or element, it can be directly on the other feature or element or intervening features and / or elements may also be present. In contrast, when a feature or element is referred to as being "directly on" another feature or element, there are no intervening features or elements present. It will also be understood that, when a feature or element is referred to as being "connected", "attached" or "coupled" to another feature or element, it can be directly connected, attached or coupled to the other feature or element or intervening features or elements may be present. In contrast, when a feature or element is referred to as being "directly connected", "directly attached" or "directly coupled" to another feature or element, there are no intervening features or elements present. Although described or shown with respect to one embodiment, the features and elements so described or shown can apply to other embodiments. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed "adjacent" another feature may have portions that overlap or underlie the adjacent feature.

[0090] Terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. For example, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items and may be abbreviated as " / ".

[0091] Spatially relative terms, such as "under", "below", "lower", "over", "upper" and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is inverted, elements described as "under”, or "beneath"- 19 -SG Docket No.: 13668-749.600other elements or features would then be oriented "over" the other elements or features. Thus, the exemplary term "under" can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Similarly, the terms "upwardly", "downwardly", "vertical", "horizontal" and the like are used herein for the purpose of explanation only unless specifically indicated otherwise.

[0092] Although the terms “first” and “second” may be used herein to describe various features / elements (including steps), these features / elements should not be limited by these terms, unless the context indicates otherwise. These terms may be used to distinguish one feature / element from another feature / element. Thus, a first feature / element discussed below could be termed a second feature / element, and similarly, a second feature / element discussed below could be termed a first feature / element without departing from the teachings of the present invention.

[0093] In general, any of the apparatuses and methods described herein should be understood to be inclusive, but all or a sub-set of the components and / or steps may alternatively be exclusive and may be expressed as “consisting of’ or alternatively “consisting essentially of’ the various components, steps, sub-components or sub-steps.

[0094] As used herein in the specification and claims, including as used in the examples and unless otherwise expressly specified, all numbers may be read as if prefaced by the word "about" or “approximately,” even if the term does not expressly appear. The phrase “about” or “approximately” may be used when describing magnitude and / or position to indicate that the value and / or position described is within a reasonable expected range of values and / or positions. For example, a numeric value may have a value that is + / - 0.1% of the stated value (or range of values), + / - 1% of the stated value (or range of values), + / - 2% of the stated value (or range of values), + / - 5% of the stated value (or range of values), + / - 10% of the stated value (or range of values), etc. Any numerical values given herein should also be understood to include about or approximately that value, unless the context indicates otherwise. For example, if the value " 10" is disclosed, then "about 10" is also disclosed. Any numerical range recited herein is intended to include all sub-ranges subsumed therein. It is also understood that when a value is disclosed that "less than or equal to" the value, "greater than or equal to the value" and possible ranges between values are also disclosed, as appropriately understood by the skilled artisan. For example, if the value "X" is disclosed the "less than or equal to X" as well as "greater than or equal to X" (e.g., where X is a numerical value) is also disclosed. It is also understood that the throughout the application, data is provided in a number of different formats, and that this data, represents endpoints and starting points, and- 20 -SG Docket No.: 13668-749.600ranges for any combination of the data points. For example, if a particular data point “10” and a particular data point “15” are disclosed, it is understood that greater than, greater than or equal to, less than, less than or equal to, and equal to 10 and 15 are considered disclosed as well as between 10 and 15. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0095] Although various illustrative embodiments are described above, any of a number of changes may be made to various embodiments without departing from the scope of the invention as described by the claims. Optional features of various device and system embodiments may be included in some embodiments and not in others. Therefore, the foregoing description is provided primarily for exemplary purposes and should not be interpreted to limit the scope of the invention as it is set forth in the claims.

[0096] The examples and illustrations included herein show, by way of illustration and not of limitation, specific embodiments in which the subject matter may be practiced. As mentioned, other embodiments may be utilized and derived there from, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. Such embodiments of the inventive subject matter may be referred to herein individually or collectively by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept, if more than one is, in fact, disclosed. Thus, although specific embodiments have been illustrated and described herein, any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description.- 21 -SG Docket No.: 13668-749.600

Claims

CLAIMSWhat is claimed is:

1. An apparatus, the apparatus comprising: an elongate body; a plurality of magnetic field sources extending along a least a portion of the elongate body, wherein each magnetic field source comprises a first emitter configured to emit a magnetic field in a first orientation; a plurality of magnetic field sensors between each magnetic field sources at different longitudinal positions along the length of the at least the portion of the elongate body; and one or more processors configured to determine a shape of the at least the portion of the elongate body based on the magnetic field detectors.

2. The apparatus of claim 1, wherein each magnetic field source further comprises a second emitter configured to emit a magnetic field in a second orientation that is at an angle to the first magnetic field.

3. The apparatus of claim 1, wherein the first emitter comprises a plurality of coils.

4. The apparatus of claim 1, further comprising a controller configured to deliver a pulsed energy having a distinct frequency to each emitter of the plurality of magnetic field sources.

5. The apparatus of claim 1, wherein the plurality of magnetic field sensors comprises a plurality of magnetometers.

6. The apparatus of claim 1, wherein the elongate body comprises a catheter.

7. The apparatus of claim 1, wherein the elongate body comprises an endoscope.

8. The apparatus of claim 2, wherein the first emitter and the second emitter are substantially orthogonal.

9. The apparatus of claim 1, wherein the least a portion of the elongate body comprises a steerable distal end region.- 22 -SG Docket No.: 13668-749.60010. The apparatus of claim 1, wherein the one or more processors is configured to compensate for background magnetic interference by subtracting a coil-off sensor reading from a coil-on sensor reading to isolate a locally generated magnetic field associated with an individual magnetic field source.

11. The apparatus of claim 1, wherein each magnetic field source is driven at a distinct modulation frequency and the one or more processors isolates sensor signals using narrow-band filtering at the respective drive frequency to reduce cross-talk among adjacent magnetic field sources.

12. The apparatus of claim 2, wherein the first emitter comprises a coil oriented substantially parallel to a longitudinal axis of the elongate body and the second emitter comprises a coil oriented substantially perpendicular to the longitudinal axis.

13. The apparatus of claim 1, wherein the plurality of magnetic field sensors includes sensors positioned off-axis relative to a midline of the elongate body at a defined radial offset to ensure multiple transverse axes of each magnetometer exhibit bend-dependent signal variation.

14. The apparatus of claim 1, wherein the magnetic field sources and the magnetic field sensors are arranged in repeating units along the elongate body, each repeating unit comprising one magnetic field source flanked by a pair of magnetic field sensors longitudinally spaced from the magnetic field source.

15. The apparatus of claim 1, further comprising a flexible electronics substrate wrapped around or embedded within a wall of the elongate body, the flexible electronics substrate carrying interconnects that couple the magnetic field sources and the magnetic field sensors to one or more controllers.

16. The apparatus of claim 1, wherein the one or more processors determines a local curvature of the elongate body using a Biot-Savart model that maps magnetometer readings to curvature as a function of sensor spacing from a corresponding magnetic field source and further refines the curvature using a calibration table generated from empirical measurements.

17. The apparatus of claim 1, wherein the magnetic field sensors are connected via a plurality of discrete serial buses selected from FC, FC, or SPI, each bus addressing a different sensor to increase sampling throughput and reduce addressing conflicts.- 23 -SG Docket No.: 13668-749.60018. The apparatus of claim 1, further comprising a plurality of secondary microcontrollers disposed along the elongate body, each secondary microcontroller being configured to compute local curvature from its associated sensor data and transmit curvature results to a primary controller for shape reconstruction of the elongate body.

19. An apparatus, the apparatus comprising: an elongate body; a plurality of magnetic field sources extending along a least a portion of the elongate body, wherein each magnetic field source comprises a first emitter configured to emit a magnetic field in a first orientation and a second emitter configured to emit a magnetic field in a second orientation that is at an angle to the first magnetic field; a plurality of magnetic field sensors between each magnetic field sources at different longitudinal positions along the length of the at least the portion of the elongate body; and one or more processors configured to determine a shape of the at least the portion of the elongate body based on a relative change in local position or bend between the magnetic field sources and the magnetic field detectors.

20. An apparatus comprising: an elongate body; a plurality of magnetic field sources and a plurality of magnetic field sensors arranged helically about a circumference of the elongate body; a controller configured to drive the magnetic field sources in a time-multiplexed manner to mitigate cross-talk; and one or more processors configured to reconstruct a three-dimensional shape of at least a portion of the elongate body based on sensed local magnetic fields from multiple radial positions.

21. A method of determining a shape of an elongate body, the method comprising: generating, by a controller, a magnetic field from a plurality of magnetic field sources disposed along at least a portion of the elongate body; sensing, by a plurality of magnetic field sensors disposed along the elongate body, local magnetic field data associated with the magnetic field sources; isolating, by the controller, signals corresponding to individual magnetic field sources using time-domain multiplexing and / or frequency-domain filtering;- 24 -SG Docket No.: 13668-749.600compensating for background magnetic interference by subtracting a sensor reading obtained in a de-energized state from a sensor reading obtained in an energized state; and determining, by a processor, a shape of the at least the portion of the elongate body based on the compensated sensor readings.

22. The method of claim 21, further comprising driving each magnetic field source at a distinct frequency and applying narrow-band filtering to isolate signals from adjacent magnetic field sources.

23. The method of claim 21, wherein determining the shape comprises applying a Biot- Savart model or a dipole approximation to map magnetometer readings to curvature of the elongate body.

24. The method of claim 21, further comprising computing local curvature at a plurality of longitudinal positions and reconstructing a three-dimensional shape of the elongate body from the local curvature.

25. The method of claim 21, wherein the magnetic field sources are pulsed and the method includes subtracting coil-off readings from coil-on readings to remove external magnetic influences.

26. The method of claim 21, wherein the magnetic field sensors are positioned off-axis or in a helical pattern around a circumference of the elongate body to improve sensitivity to multi-plane bending.

27. The method of claim 21, further comprising transmitting sensor data to a plurality of secondary microcontrollers configured to compute local curvature and sending curvature results to a primary controller for shape reconstruction.

28. The method of claim 21, wherein the processor applies calibration using a look-up table generated from empirical measurements to refine curvature estimation.

29. The method of claim 21, further comprising displaying, on an output interface, a visual representation of the reconstructed shape and one or more bend metrics derived from the curvature.- 25 -SG Docket No.: 13668-749.60030. The method of claim 1, wherein the magnetic field sources comprise coils oriented in different directions, including at least one coil substantially parallel to a longitudinal axis and at least one coil substantially perpendicular to the longitudinal axis.

31. A method of determining a shape of an elongate body, the method comprising: generating, by a controller, a magnetic field from a plurality of magnetic field sources disposed along at least a portion of the elongate body; sensing, by a plurality of magnetic field sensors disposed along the elongate body, local magnetic field data associated with the magnetic field sources; and determining, by a processor, a shape of the at least the portion of the elongate body based on the local magnetic field data.- 26 -SG Docket No.: 13668-749.600

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