Patent Publication Number: US-11660147-B2

Title: Alignment techniques for percutaneous access

Description:
RELATED APPLICATION(S) 
     This application claims priority to U.S. Provisional Application No. 62/956,019, filed Dec. 31, 2019, and entitled ALIGNMENT TECHNIQUES FOR PERCUTANEOUS ACCESS, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     Field 
     The present disclosure relates to the field of medical procedures. 
     Description of the Related Art 
     Various medical procedures involve the use of one or more devices configured to penetrate the human anatomy to reach a treatment site. Certain operational processes can involve inserting the one or more devices through the skin and other anatomy of a patient to reach the treatment site and extract an object from the patient, such as a urinary stone. 
     SUMMARY 
     In some implementations, the present disclosure relates to a method comprising, by control circuitry of a medical system: receiving sensor data indicating a position of at least a portion of a medical instrument, based at least in part on the sensor data, determining an orientation of the medical instrument, determining a target location within an organ of the patient, and determining a plane that includes the target location. The method further comprises, based at least in part on the orientation of the medical instrument, determining a projected position of the medical instrument on the plane, generating interface data representing one or more interface elements indicating a first distance between the projected position and the target location on the plane; and displaying the one or more interface elements based at least in part on the interface data. 
     In some embodiments, the determining the plane includes determining the plane such that a heading of the medical instrument is normal to the plane. The method can further comprise updating an orientation of the plane as the orientation of the medical instrument changes such that the heading of the medical instrument remains normal to the plane. 
     In some embodiments, the determining the plane includes determining a line between a distal end of the medical instrument and the target location and determining the plane such that the line is normal to the plane. The method can further comprise maintaining an orientation of the plane as the orientation of the medical instrument changes. 
     In some embodiment, the determining the target location is based at least in part on additional sensor data from a scope. Further, the determining the plane includes determining the plane such that a heading of the scope is normal to the plane. 
     In some embodiments, the displaying the one or more interface elements includes displaying a first interface element of the one or more interface elements a second distance from a center of a second interface element of the one or more interface elements. The second distance can be based at least in part on the first distance and an insertion distance between a tip of the medical instrument and the target location on the plane. 
     In some embodiments, the method further comprises displaying a progress indicator indicating a proximity of a tip of the medical instrument to the target location, setting a progress change parameter for the progress indicator to a first value, the progress change parameter being indicative of an amount of progress change of the progress indicator with respect to a unit of movement of the medical instrument, determining that the tip of the medical instrument has moved closer to the target location, and based at least in part on determining that the tip of the medical instrument has moved closer to the target location, setting the progress change parameter to a second value. The second value can be associated with a greater amount of progress change of the progress indicator for the unit of movement of the medical instrument than the first value. 
     In some implementations, the present disclosure relates to a medical system comprising a communication interface configured to receive sensor data from a medical instrument that is configured to access a human anatomy percutaneously, and control circuitry communicatively coupled to the communication interface. The control circuitry is configured to based at least in part on the sensor data, determine an orientation of the medical instrument, determine a target location within the human anatomy, determine a plane that includes the target location, based at least in part on the orientation of the medical instrument, determine a projected position of the medical instrument on the plane; and generate interface data representing one or more interface elements indicating a distance between the projected position and the target location on the plane. 
     In some embodiments, the medical system further comprises an endoscope configured to access the target location via a lumen of the human anatomy. The endoscope can include a sensor that is configured to provide additional sensor data to the communication interface. The control circuitry can be configured to determine the target location based at least in part on the additional sensor data. 
     In some embodiments, the control circuitry is configured to determine the plane such that a heading of the medical instrument is normal to the plane. The control circuitry can be further configured to update an orientation of the plane as the orientation of the medical instrument changes such that the heading of the medical instrument remains normal to the plane. 
     In some embodiments, the control circuitry is configured to determine the plane by determining a line between a distal end of the medical instrument and the target location and determining the plane such that the line is normal to the plane. The control circuitry can be further configured to maintain an orientation of the plane as the orientation of the medical instrument changes. 
     In some embodiments, the medical system includes a robotic system coupled to a device that is configured to generate a signal and the sensor data is based at least in part on the signal. The control circuitry can be further configured to determine a coordinate frame for the medical instrument based at least in part on a coordinate frame for the robotic system, and cause the one or more interface elements to move within an interface in a direction that is correlated to a direction of movement of the medical instrument relative to the coordinate frame for the medical instrument. 
     In some embodiments, the control circuitry is further configured to set a position change parameter to a first value, determine that the medical instrument has moved closer to the target location, and set the position change parameter to a second value. The position change parameter can be indicative of an amount of position change of the one or more interface elements within an interface with respect to a unit of movement of the medical instrument. The second value can be associated with a greater amount of position change of the one or more interface elements within the interface for the unit of movement of the medical instrument than the first value. 
     In some embodiments, the control circuitry is further configured to cause a progress indicator to be displayed indicating a proximity of the medical instrument to the target location, set a progress change parameter for the progress indicator to a first value, determine that the medical instrument has moved closer to the target location, and set the progress change parameter to a second value. The progress change parameter can be indicative of an amount of progress change of the progress indicator with respect to a unit of movement of the medical instrument. The second value can be associated with a greater amount of progress change of the progress indicator for the unit of movement of the medical instrument than the first value. 
     In some implementations, the present disclosure relates to one or more non-transitory computer-readable media storing computer-executable instructions that, when executed by control circuitry, cause the control circuitry to perform operations comprising determining an orientation of a medical instrument that is configured to access a human anatomy percutaneously, determining a target location within the human anatomy, determining a plane that includes the target location, based at least in part on the orientation of the medical instrument, determining a projected position of the medical instrument on the plane, and generating interface data representing one or more interface elements indicating a first distance between the projected position and the target location on the plane. 
     In some embodiments, a heading of the medical instrument is normal to the plane. The operations can further comprise updating an orientation of the plane as the orientation of the medical instrument changes such that the heading of the medical instrument remains normal to the plane. 
     In some embodiments, the plane is normal to a line between a distal end of the medical instrument and the target location. The operations can further comprise maintaining an orientation of the plane as the orientation of the medical instrument changes. 
     In some embodiments, the operations further comprise displaying a first interface element of the one or more interface elements a second distance from a center of a second interface element of the one or more interface elements. The second distance can be based at least in part on the first distance. The second distance can be further based at least in part on an insertion distance between a tip of the medical instrument and the target location on the plane. 
     In some embodiments, the operations further comprise causing a progress indicator to be displayed indicating a proximity of the medical instrument to the target location, based at least in part on the medical instrument moving closer to the target location a first time by a first amount, updating the progress indicator by a second amount, and based at least in part on the medical instrument moving closer to the target location a second time by the first amount, updating the progress indicator by a third amount that is greater than the first amount. 
     In some embodiments, the operations further comprise generating progress region data indicating multiple regions for an environment of the medical instrument, based at least in part on the first sensor data and the progress region data, determining a region, from among the multiple regions, in which the medical instrument is located, determining a state of the medical instrument based at least in part on the region, and causing an indication to be displayed of the state. 
     In some implementations, the present disclosure relates to a method comprising receiving, by control circuitry of a medical system, first sensor data from a needle that is configured to be inserted into a patient percutaneously, based at least in part on the first sensor data, determining, by the control circuitry, a pose of the needle, receiving, by the control circuitry, second sensor data from an endoscope that is disposed at least partially within an anatomical lumen of the patient, based at least in part on the second sensor data, determining, by the control circuitry, a target location within an organ of the patient, determining, by the control circuitry, a plane that includes the target location, based at least in part on the pose of the needle, determining, by the control circuitry, a projected position of the needle on the plane, and generating interface data representing one or more interface elements indicating a distance between the projected position and the target location on the plane. 
     In some embodiments, the method further comprises displaying the one or more interface elements in an interface, identifying a scaling ratio of dimensions represented on the plane to dimensions represented on the interface, determining that the needle has moved closer to the target location; and based at least in part on determining that the needle has moved closer to the target location, updating the scaling ratio. 
     In some embodiments, the method further comprises setting a position change parameter to a first value, determining that the medical instrument has moved closer to the target location, based at least in part on determining that the medical instrument has moved closer to the target location, setting the position change parameter to a second value. The position change parameter can be indicative of an amount of position change of the one or more interface elements within an interface with respect to a unit of position or orientation change of the needle. The second value can be associated with a greater amount of position change of the one or more interface elements within the interface for the unit of position or orientation change of the needle than the first value. 
     In some embodiments, the medical system includes a robotic arm coupled to an electromagnetic field generator, and the first sensor data is based at least in part on electromagnetic fields from the electromagnetic field generator. The method can further comprise determining a world coordinate frame for a robotic system associated with the robotic arm, representing the pose of the needle in the world coordinate frame, representing the plane in the world coordinate frame, determining a target coordinate frame for the plane represented in the world coordinate frame based at least in part on the pose of the needle within the world coordinate frame, determining a coordinate frame for the needle based at least in part on the target coordinate frame, and moving the one or more interface elements within an interface in a direction that is correlated to a direction of movement of the needle relative to the coordinate frame for the needle. 
     For purposes of summarizing the disclosure, certain aspects, advantages and features have been described. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, the disclosed embodiments can be carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as can be taught or suggested herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments are depicted in the accompanying drawings for illustrative purposes and should in no way be interpreted as limiting the scope of the disclosure. In addition, various features of different disclosed embodiments can be combined to form additional embodiments, which are part of this disclosure. Throughout the drawings, reference numbers may be reused to indicate correspondence between reference elements. 
         FIG.  1    illustrates an embodiment of a medical system configured to implement the techniques discussed herein in accordance with one or more embodiments. 
         FIG.  2    illustrates an example interface to provide information regarding a position and/or an orientation of a medical instrument in accordance with one or more embodiments. 
         FIG.  3    illustrates a top view of the medical system of  FIG.  1    arranged to assist in inserting a scope into a patient in accordance with one or more embodiments. 
         FIG.  4    illustrates a top view of the medical system of  FIG.  1    arranged to navigate a scope within a patient in accordance with one or more embodiments. 
         FIG.  5    illustrates a top view of the medical system of  FIG.  1    arranged to assist in inserting a needle into a patient in accordance with one or more embodiments. 
         FIGS.  6 - 1  through  6 - 11    illustrate example interfaces to provide information regarding an alignment and/or a progress of a medical instrument during a procedure in accordance with one or more embodiments. 
         FIG.  7    illustrates an example flow diagram of a process for determining an alignment of a medical instrument relative to a target trajectory and presenting information regarding the alignment in accordance with one or more embodiments. 
         FIG.  8    illustrates an example flow diagram of a process for presenting information regarding an orientation of a medical instrument in accordance with one or more embodiments. 
         FIG.  9    illustrates an example flow diagram of a process for presenting information regarding a proximity of a medical instrument to a target location in accordance with one or more embodiments. 
         FIG.  10    illustrates an example flow diagram of a process for setting and/or updating a position change parameter associated with an instrument-alignment element in accordance with one or more embodiments. 
         FIG.  11    illustrates example details of the robotic system of  FIG.  1    in accordance with one or more embodiments. 
         FIG.  12    illustrates example details of the control system of  FIG.  1    in accordance with one or more embodiments. 
         FIGS.  13 - 1  through  13 - 3    illustrate example techniques of mapping a pose of a medical instrument onto a representation/plane that remains fixed as the pose of the medical instrument changes in accordance with one or more embodiments. 
         FIGS.  14 - 1  through  14 - 3    illustrate example techniques of mapping a pose of a medical instrument onto a representation/plane that updates as the pose of the medical instrument changes in accordance with one or more embodiments. 
         FIGS.  15 - 1  through  15 - 3    illustrate another example of mapping a pose of a medical instrument onto a representation/plane that updates as the pose of the medical instrument changes in accordance with one or more embodiments. 
         FIGS.  16 - 1  through  16 - 3    illustrate a further example of mapping a pose of a medical instrument onto a representation/plane that updates as the pose of the medical instrument changes in accordance with one or more embodiments. 
         FIG.  17    illustrates example techniques for establishing one or more coordinate frames to correlate movement of a medical instrument to movement of an interface element within an interface in accordance with one or more embodiments. 
         FIGS.  18 - 1 A,  18 - 1 B,  18 - 2 A, and  18 - 2 B  illustrate example adaptive targeting techniques for an interface in accordance with one or more embodiments. 
         FIGS.  19 - 1  and  19 - 2    illustrate example techniques of scaling a target plane based on an insertion distance of a medical instrument in accordance with one or more embodiments. 
         FIG.  19 - 3    illustrates an example graph of a scaling of a target plane relative to a distance of a medical instrument to a target location in accordance with one or more embodiments. 
         FIG.  20    illustrates an example anatomical visualization that can be provided via an interface to assist a user in navigating a medical instrument in accordance with one or more embodiments. 
         FIG.  21    illustrates example regions that can be implemented/generated to determine a state of a medical instrument in accordance with one or more embodiments. 
         FIG.  22    illustrates an example graph of a progress percentage relative to a distance of a medical instrument to a target location in accordance with one or more embodiments. 
         FIG.  23    illustrates an example flow diagram of a process for generating data indicating a distance between a projected position of a medical instrument on a plane and a target location on the plane in accordance with one or more embodiments. 
         FIG.  24    illustrates an example flow diagram of a process for updating an amount of progress indicated for a unit of movement of a medical instrument in accordance with one or more embodiments. 
         FIG.  25    illustrates an example flow diagram of a process for updating a position change parameter indicative of an amount of position change of an interface element for a unit of orientation/movement change of a medical instrument in accordance with one or more embodiments. 
         FIG.  26    an example flow diagram of a process for updating a scaling ratio of a plane to an interface in accordance with one or more embodiments. 
         FIG.  27    illustrates an example flow diagram of a process for determining a coordinate frame for a medical instrument and/or correlating movement of an interface element to movement of the medical instrument in accordance with one or more embodiments. 
         FIG.  28    illustrates an example flow diagram of a process for determining a state of a medical instrument based on a region in which the medical instrument is located in accordance with one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The headings provided herein are for convenience only and do not necessarily affect the scope or meaning of disclosure. Although certain preferred embodiments and examples are disclosed below, the subject matter extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and to modifications and equivalents thereof. Thus, the scope of the claims that may arise here from is not limited by any of the particular embodiments described below. For example, in any method or process disclosed herein, the acts or operations of the method or process may be performed in any suitable sequence and are not necessarily limited to any particular disclosed sequence. Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding certain embodiments; however, the order of description should not be construed to imply that these operations are order dependent. Additionally, the structures, systems, and/or devices described herein may be embodied as integrated components or as separate components. For purposes of comparing various embodiments, certain aspects and advantages of these embodiments are described. Not necessarily all such aspects or advantages are achieved by any particular embodiment. Thus, for example, various embodiments may be carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other aspects or advantages as may also be taught or suggested herein. 
     Certain standard anatomical terms of location may be used herein to refer to the anatomy of animals, and namely humans, with respect to the preferred embodiments. Although certain spatially relative terms, such as “outer,” “inner,” “upper,” “lower,” “below,” “above,” “vertical,” “horizontal,” “top,” “bottom,” and similar terms, are used herein to describe a spatial relationship of one device/element or anatomical structure to another device/element or anatomical structure, it is understood that these terms are used herein for ease of description to describe the positional relationship between element(s)/structures(s), as illustrated in the drawings. It should be understood that spatially relative terms are intended to encompass different orientations of the element(s)/structures(s), in use or operation, in addition to the orientations depicted in the drawings. For example, an element/structure described as “above” another element/structure may represent a position that is below or beside such other element/structure with respect to alternate orientations of the subject patient or element/structure, and vice-versa. 
     Overview 
     The present disclosure relates to systems, devices, and methods for assisting a physician or other user in aligning a medical instrument for percutaneous access to a location within the human anatomy. Although certain aspects of the present disclosure are described in detail herein in the context of renal, urological, and/or nephrological procedures, such as kidney stone removal/treatment procedures, it should be understood that such context is provided for convenience and clarity, and the concepts disclosed herein are applicable to any suitable medical procedure. However, as mentioned, description of the renal/urinary anatomy and associated medical issues and procedures is presented below to aid in the description of the concepts disclosed herein. 
     Kidney stone disease, also known as urolithiasis, is a relatively common medical condition that involves the formation, in the urinary tract, of a solid piece of material, referred to as “kidney stones,” “urinary stones,” “renal calculi,” “renal lithiasis,” or “nephrolithiasis.” Urinary stones can be formed and/or found in the kidneys, the ureters, and the bladder (referred to as “bladder stones”). Such urinary stones form as a result of concentrated minerals and can cause significant abdominal pain once they reach a size sufficient to impede urine flow through the ureter or urethra. Urinary stones can be formed from calcium, magnesium, ammonia, uric acid, cysteine, and/or other compounds. 
     To remove urinary stones from the bladder and ureter, surgeons can insert a ureteroscope into the urinary tract through the urethra. Typically, a ureteroscope includes an endoscope at its distal end configured to enable visualization of the urinary tract. The ureteroscope can also include a lithotomy mechanism to capture or break apart urinary stones. During a ureteroscopy procedure, one physician/technician can control the position of the ureteroscope, while another other physician/technician can control the lithotomy mechanism. 
     In order to remove relatively large stones from the kidneys (i.e., “kidney stones”), physicians can use a percutaneous nephrolithotomy (“PCNL”) technique that includes inserting a nephroscope through the skin to break up and/or remove the stone(s). Locating the kidney stone(s) can be achieved using fluoroscopy to provide a target for insertion of the nephroscope. However, fluoroscopy increases the cost of the nephrolithotomy procedure due to the cost of the fluoroscope itself as well as the cost of a technician to operate the fluoroscope. Fluoroscopy also exposes the patient to radiation for a prolonged period of time. Even with fluoroscopy, accurately making a percutaneous incision to access the kidney stone can be difficult and undesirably imprecise. Furthermore, some nephrolithotomy techniques involve a two-day or three-day inpatient stay. In sum, certain nephrolithotomy techniques can be relatively costly and problematic for patients. 
     In some implementations, the present disclosure relates to techniques and systems to assist in aligning a medical instrument for percutaneous access to a target location within the human anatomy. For example, to perform a medical procedure, a physician or other user can use a medical instrument to access a target location within a patient, such as to remove a kidney stone located within the kidneys. The target location can represent a desired location for the medical instrument to access the anatomy of the patient, such as a desired papilla or other location within the kidney. The techniques and systems discussed herein can provide information regarding an orientation/position of the medical instrument to assist the physician or other user in aligning the medical instrument with the appropriate orientation and/or inserting the medical instrument into the patient to reach the target location. For example, the techniques and systems can provide a visual representation indicating a current orientation of the medical instrument relative to a target trajectory/pose, a visual representation indicating a proximity of the medical instrument to the target location, and/or other information regarding the medical instrument and/or procedure. The target trajectory can represent a desired path for accessing the target location from an entry point on the patient, such as from a position on the skin of the patient. By providing such information, the physician or other user can accurately maneuver/manipulate the medical instrument to reach the target location and perform the medical procedure in a manner that minimizes damage to the anatomy of the patient. 
     In many embodiments, the techniques and systems are discussed in the context of a percutaneous procedure, which can include any procedure where access is gained to a target location by making a puncture and/or incision in the skin, mucous membrane, and/or other body layer. However, it should be understood that the techniques and systems can be implemented in the context of any medical procedure including, for example, minimally invasive procedures (e.g., a laparoscopy), non-invasive procedures (e.g., an endoscopy), therapeutic procedures, diagnostic procedures, percutaneous procedures, non-percutaneous procedures, or other types of procedures. An endoscopic procedure can include a bronchoscopy, a ureteroscopy, a gastroscopy, nephroscopy, nephrolithotomy, and so on. In some embodiments, in the context of a laparoscopic procedure or another procedure, the techniques and systems can be used to align a first medical instrument to a second medical instrument/anatomical position, such as to guide port placement (e.g., to align a first trocar to a second trocar/anatomical position). Further, in some embodiments, in the context of a diagnostic procedure, the techniques and systems can be used to align an ultrasound probe equipped with an Electromagnetic sensor to an anatomical target or to guide a user to a set of target orientations to reconstruct anatomy, such as three-dimensional (3D) kidney anatomy. Moreover, in some embodiments, in the context of an endoscopic procedure, the techniques and systems can be used to guide a position of a bronchoscope while performing a biopsy at a marked location, such as a location of a tumor. 
     Medical System 
       FIG.  1    illustrates an example medical system  100  for performing various medical procedures in accordance with aspects of the present disclosure. The medical system  100  includes a robotic system  110  configured to engage with and/or control a medical instrument  120  to perform a procedure on a patient  130 . The medical system  100  also includes a control system  140  configured to interface with the robotic system  110 , provide information regarding the procedure, and/or perform a variety of other operations. For example, the control system  140  can include a display(s)  142  to present certain information to assist the physician  160 . The medical system  100  can include a table  150  configured to hold the patient  130 . The system  100  can further include an electromagnetic (EM) field generator  180 , which can be held by one or more robotic arms  112  of the robotic system  110  or can be a stand-alone device. In examples, the medical system  100  can also include an imaging device  190  which can be integrated into a C-arm and/or configured to provide imaging during a procedure, such as for a fluoroscopy-type procedure. Although shown in  FIG.  1   , in some embodiments the imaging device  190  is eliminated. 
     In some implementations, the medical system  100  can be used to perform a percutaneous procedure. For example, if the patient  130  has a kidney stone that is too large to be removed through a urinary tract, the physician  160  can perform a procedure to remove the kidney stone through a percutaneous access point on the patient  130 . To illustrate, the physician  160  can interact with the control system  140  to control the robotic system  110  to advance and navigate the medical instrument  120  (e.g., a scope) from the urethra, through the bladder, up the ureter, and into the kidney where the stone is located. The control system  140  can provide information via the display(s)  142  regarding the medical instrument  120  to assist the physician  160  in navigating the medical instrument  120 , such as real-time images captured therewith. 
     Once at the site of the kidney stone (e.g., within a calyx of the kidney), the medical instrument  120  can be used to designate/tag a target location for the medical instrument  170  to access the kidney percutaneously (e.g., a desired point to access the kidney). To minimize damage to the kidney and/or the surrounding anatomy, the physician  160  can designate a particular papilla as the target location for entering into the kidney with the medical instrument  170 . However, other target locations can be designated or determined. To assist the physician in inserting the medical instrument  170  into the patient  130  through the particular papilla, the control system  140  can provide an instrument alignment interface  144 , which can include a visualization to indicate an alignment of an orientation of the medical instrument  170  relative to a target trajectory (e.g., a desired access path), a visualization to indicate a progress of inserting the medical instrument  170  towards the target location, and/or other information. Once the medical instrument  170  has reached the target location, the physician  160  can use the medical instrument  170  and/or another medical instrument to extract the kidney stone from the patient  130 , such as through the percutaneous access point. 
     Although the above percutaneous procedure and/or other procedures are discussed in the context of using the medical instrument  120 , in some implementations a percutaneous procedure can be performed without the assistance of the medical instrument  120 . Further, the medical system  100  can be used to perform a variety of other procedures. 
     Moreover, although many embodiments describe the physician  160  using the medical instrument  170 , the medical instrument  170  can alternatively be used by a component of the medical system  100 . For example, the medical instrument  170  can be held/manipulated by the robotic system  110  (e.g., the one or more robotic arms  112 ) and the techniques discussed herein can be implemented to control the robotic system  110  to insert the medical instrument  170  with the appropriate orientation to reach a target location. 
     In the example of  FIG.  1   , the medical instrument  120  is implemented as a scope and the medical instrument  170  is implemented as a needle. Thus, for ease of discussion, the medical instrument  120  is referred to as “the scope  120 ” or “the lumen-based medical instrument  120 ,” and the medical instrument  170  is referred to as “the needle  170 ” or “the percutaneous medical instrument  170 .” However, the medical instrument  120  and the medical instrument  170  can each be implemented as an suitable type of medical instrument including, for example, a scope (sometimes referred to as an “endoscope”), a needle, a catheter, a guidewire, a lithotripter, a basket retrieval device, forceps, a vacuum, a needle, a scalpel, an imaging probe, jaws, scissors, graspers, needle holder, micro dissector, staple applier, tacker, suction/irrigation tool, clip applier, and so on. In some embodiments, a medical instrument is a steerable device, while other embodiments a medical instrument is a non-steerable device. In some embodiments, a surgical tool refers to a device that is configured to puncture or to be inserted through the human anatomy, such as a needle, a scalpel, a guidewire, and so on. However, a surgical tool can refer to other types of medical instruments. 
     In some embodiments, a medical instrument, such as the scope  120  and/or the needle  170 , includes a sensor that is configured to generate sensor data, which can be sent to another device. In examples, sensor data can indicate a location/orientation of the medical instrument and/or can be used to determine a location/orientation of the medical instrument. For instance, a sensor can include an electromagnetic (EM) sensor with a coil of conductive material. Here, an EM field generator, such as the EM field generator  180 , can provide an EM field that is detected by the EM sensor on the medical instrument. The magnetic field can induce small currents in coils of the EM sensor, which can be analyzed to determine a distance and/or angle/orientation between the EM sensor and the EM field generator. Further, a medical instrument can include other types of sensors configured to generate sensor data, such as a camera, a range sensor, a radar device, a shape sensing fiber, an accelerometer, a gyroscope, an accelerometer, a satellite-based positioning sensor (e.g., a global positioning system (GPS)), a radio-frequency transceiver, and so on. In some embodiments, a sensor is positioned on a distal end of a medical instrument, while in other embodiments a sensor is positioned at another location on the medical instrument. In some embodiments, a sensor on a medical instrument can provide sensor data to the control system  140  and the control system  140  can perform one or more localization techniques to determine/track a position and/or an orientation of a medical instrument. 
     The term “scope” or “endoscope” are used herein according to their broad and ordinary meanings and can refer to any type of elongate medical instrument having image generating, viewing, and/or capturing functionality and configured to be introduced into any type of organ, cavity, lumen, chamber, and/or space of a body. For example, references herein to scopes or endoscopes can refer to a ureteroscope (e.g., for accessing the urinary tract), a laparoscope, a nephroscope (e.g., for accessing the kidneys), a bronchoscope (e.g., for accessing an airway, such as the bronchus), a colonoscope (e.g., for accessing the colon), an arthroscope (e.g., for accessing a joint), a cystoscope (e.g., for accessing the bladder), a borescope, and so on. 
     A scope can comprise a tubular and/or flexible medical instrument that is configured to be inserted into the anatomy of a patient to capture images of the anatomy. In some embodiments, a scope can accommodate wires and/or optical fibers to transfer signals to/from an optical assembly and a distal end of the scope, which can include an imaging device, such as an optical camera. The camera/imaging device can be used to capture images of an internal anatomical space, such as a target calyx/papilla of a kidney. A scope can further be configured to accommodate optical fibers to carry light from proximately-located light sources, such as light-emitting diodes, to the distal end of the scope. The distal end of the scope can include ports for light sources to illuminate an anatomical space when using the camera/imaging device. In some embodiments, the scope is configured to be controlled by a robotic system, such as the robotic system  110 . The imaging device can comprise an optical fiber, fiber array, and/or lens. The optical components can move along with the tip of the scope such that movement of the tip of the scope results in changes to the images captured by the imaging device. 
     A scope can be articulable, such as with respect to at least a distal portion of the scope, so that the scope can be steered within the human anatomy. In some embodiments, a scope is configured to be articulated with, for example, five or six degrees of freedom, including X, Y, Z coordinate movement, as well as pitch, yaw, and roll. A position sensor(s) of the scope can likewise have similar degrees of freedom with respect to the position information they produce/provide. A scope can include telescoping parts, such as an inner leader portion and an outer sheath portion, which can be manipulated to telescopically extend the scope. A scope, in some instances, can comprise a rigid or flexible tube, and can be dimensioned to be passed within an outer sheath, catheter, introducer, or other lumen-type device, or can be used without such devices. In some embodiments, a scope includes a working channel for deploying medical instruments (e.g., lithotripters, basketing devices, forceps, etc.), irrigation, and/or aspiration to an operative region at a distal end of the scope. 
     The robotic system  110  can be configured to at least partly facilitate execution of a medical procedure. The robotic system  110  can be arranged in a variety of ways depending on the particular procedure. The robotic system  110  can include the one or more robotic arms  112  configured to engage with and/or control the scope  120  to perform a procedure. As shown, each robotic arm  112  can include multiple arm segments coupled to joints, which can provide multiple degrees of movement. In the example of  FIG.  1   , the robotic system  110  is positioned proximate to the patient&#39;s  130  legs and the robotic arms  112  are actuated to engage with and position the scope  120  for access into an access point, such as the urethra of the patient  130 . When the robotic system  110  is properly positioned, the scope  120  can be inserted into the patient  130  robotically using the robotic arms  112 , manually by the physician  160 , or a combination thereof. The robotic arms  112  can also be connected to the EM field generator  180 , which can be positioned near a treatment site, such as within proximity to the kidneys of the patient  130 . 
     The robotic system  110  can also include a support structure  114  coupled to the one or more robotic arms  112 . The support structure  114  can include control electronics/circuitry, one or more power sources, one or more pneumatics, one or more optical sources, one or more actuators (e.g., motors to move the one or more robotic arms  112 ), memory/data storage, and/or one or more communication interfaces. In some embodiments, the support structure  114  includes an input/output (I/O) device(s)  116  configured to receive input, such as user input to control the robotic system  110 , and/or provide output, such as a graphical user interface (GUI), information regarding the robotic system  110 , information regarding a procedure, and so on. The I/O device(s)  116  can include a display, a touchscreen, a touchpad, a projector, a mouse, a keyboard, a microphone, a speaker, etc. In some embodiments, the robotic system  110  is movable (e.g., the support structure  114  includes wheels) so that the robotic system  110  can be positioned in a location that is appropriate or desired for a procedure. In other embodiments, the robotic system  110  is a stationary system. Further, in some embodiments, the robotic system  112  is integrated into the table  150 . 
     The robotic system  110  can be coupled to any component of the medical system  100 , such as the control system  140 , the table  150 , the EM field generator  180 , the scope  120 , and/or the needle  170 . In some embodiments, the robotic system is communicatively coupled to the control system  140 . In one example, the robotic system  110  can be configured to receive a control signal from the control system  140  to perform an operation, such as to position a robotic arm  112  in a particular manner, manipulate the scope  120 , and so on. In response, the robotic system  110  can control a component of the robotic system  110  to perform the operation. In another example, the robotic system  110  is configured to receive an image from the scope  120  depicting internal anatomy of the patient  130  and/or send the image to the control system  140 , which can then be displayed on the display(s)  142 . Furthermore, in some embodiments, the robotic system  110  is coupled to a component of the medical system  100 , such as the control system  140 , in such a manner as to allow for fluids, optics, power, or the like to be received therefrom. Example details of the robotic system  110  are discussed in further detail below in reference to  FIG.  11   . 
     The control system  140  can be configured to provide various functionality to assist in performing a medical procedure. In some embodiments, the control system  140  can be coupled to the robotic system  110  and operate in cooperation with the robotic system  110  to perform a medical procedure on the patient  130 . For example, the control system  140  can communicate with the robotic system  110  via a wireless or wired connection (e.g., to control the robotic system  110  and/or the scope  120 , receive an image(s) captured by the scope  120 , etc.), provide fluids to the robotic system  110  via one or more fluid channels, provide power to the robotic system  110  via one or more electrical connections, provide optics to the robotic system  110  via one or more optical fibers or other components, and so on. Further, in some embodiments, the control system  140  can communicate with the needle  170  and/or the scope  170  to receive sensor data from the needle  170  and/or the endoscope  120  (via the robotic system  110  and/or directly from the needle  170  and/or the endoscope  120 ). Moreover, in some embodiments, the control system  140  can communicate with the table  150  to position the table  150  in a particular orientation or otherwise control the table  150 . Further, in some embodiments, the control system  140  can communicate with the EM field generator  180  to control generation of an EM field around the patient  130 . 
     The control system  140  includes various I/O devices configured to assist the physician  160  or others in performing a medical procedure. In this example, the control system  140  includes an I/O device(s)  146  that is employed by the physician  160  or other user to control the scope  120 , such as to navigate the scope  120  within the patient  130 . For example, the physician  160  can provide input via the I/O device(s)  146  and, in response, the control system  140  can send control signals to the robotic system  110  to manipulate the scope  120 . Although the I/O device(s)  146  is illustrated as a controller in the example of  FIG.  1   , the I/O device(s)  146  can be implemented as a variety of types of I/O devices, such as a touchscreen, a touch pad, a mouse, a keyboard, etc. 
     As also shown in  FIG.  1   , the control system  140  can include the display(s)  142  to provide various information regarding a procedure. As noted above, the display(s)  142  can present the instrument alignment interface  144  to assist the physician  160  in manipulating the needle  170 . The display(s)  142  can also provide (e.g., via the instrument alignment interface  144  and/or another interface) information regarding the scope  120 . For example, the control system  140  can receive real-time images that are captured by the scope  120  and display the real-time images via the display(s)  142 . An example instrument alignment interface is illustrated in  FIG.  2   . Additionally or alternatively, the control system  140  can receive signals (e.g., analog, digital, electrical, acoustic/sonic, pneumatic, tactile, hydraulic, etc.) from a medical monitor and/or a sensor associated with the patient  130 , and the display(s)  142  can present information regarding the health or environment of the patient  130 . Such information can include information that is displayed via a medical monitor including, for example, a heart rate (e.g., ECG, HRV, etc.). blood pressure/rate, muscle bio-signals (e.g., EMG), body temperature, blood oxygen saturation (e.g., SpO 2 ), CO 2 , brainwaves (e.g., EEG), environmental and/or local or core body temperature, and so on. 
     To facilitate the functionality of the control system  140 , the control system  140  can include various components (sometimes referred to as “subsystems”). For example, the control system  140  can include control electronics/circuitry, as well as one or more power sources, pneumatics, optical sources, actuators, memory/data storage devices, and/or communication interfaces. In some embodiments, the control system  140  includes control circuitry comprising a computer-based control system that is configured to store executable instructions, that when executed, cause various operations to be implemented. In some embodiments, the control system  140  is movable, such as that shown in  FIG.  1   , while in other embodiments, the control system  140  is a stationary system. Although various functionality and components are discussed as being implemented by the control system  140 , any of this functionality and/or components can be integrated into and/or performed by other systems and/or devices, such as the robotic system  110 , the table  150 , and/or the EM generator  180  (or even the scope  120  and/or the needle  170 ). Example details of the control system  140  are discussed in further detail below in reference to  FIG.  12   . 
     The imaging device  190  can be configured to capture/generate one or more images of the patient  130  during a procedure, such as one or more x-ray or CT images. In examples, images from the imaging device  190  can be provided in real-time to view anatomy and/or medical instruments, such as the scope  120  and/or the needle  170 , within the patient  130  to assist the physician  160  in performing a procedure. The imaging device  190  can be used to perform a fluoroscopy (e.g., with a contrast dye within the patient  130 ) or another type of imaging technique. Although shown in  FIG.  1   , in many embodiments the imaging device  190  is not implemented for performing a procedure and/or the imaging device  190  (including the C-arm) is eliminated. 
     The various components of the medical system  100  can be communicatively coupled to each other over a network, which can include a wireless and/or wired network. Example networks include one or more personal area networks (PANs), local area networks (LANs), wide area networks (WANs), Internet area networks (IANs), cellular networks, the Internet, etc. Further, in some embodiments, the components of the medical system  100  are connected for data communication, fluid/gas exchange, power exchange, and so on, via one or more support cables, tubes, or the like. 
     The medical system  100  can provide a variety of benefits, such as providing guidance to assist a physician in performing a procedure (e.g., instrument tracking, instrument alignment information, etc.), enabling a physician to perform a procedure from an ergonomic position without the need for awkward arm motions and/or positions, enabling a single physician to perform a procedure with one or more medical instruments, avoiding radiation exposure (e.g., associated with fluoroscopy techniques), enabling a procedure to be performed in a single-operative setting, providing continuous suction to remove an object more efficiently (e.g., to remove a kidney stone), and so on. For example, the medical system  100  can provide guidance information to assist a physician in using various medical instruments to access a target anatomical feature while minimizing bleeding and/or damage to anatomy (e.g., critical organs, blood vessels, etc.). Further, the medical system  100  can provide non-radiation-based navigational and/or localization techniques to reduce physician and patient exposure to radiation and/or reduce the amount of equipment in the operating room. Moreover, the medical system  100  can provide functionality that is distributed between at least the control system  140  and the robotic system  110 , which can be independently movable. Such distribution of functionality and/or mobility can enable the control system  140  and/or the robotic system  110  to be placed at locations that are optimal for a particular medical procedure, which can maximize working area around the patient and/or provide an optimized location for a physician to perform a procedure. 
     Although various techniques and systems are discussed as being implemented as robotically-assisted procedures (e.g., procedures that at least partly use the medical system  100 ), the techniques and systems can be implemented in other procedures, such as in fully-robotic medical procedures, human-only procedures (e.g., free of robotic systems), and so on. For example, the medical system  100  can be used to perform a procedure without a physician holding/manipulating a medical instrument (e.g., a fully-robotic procedure). That is, medical instruments that are used during a procedure, such as the scope  120  and the needle  170 , can each be held/controlled by components of the medical system  100 , such as the robotic arm(s)  112  of the robotic system  110 . 
     Example Interface 
       FIG.  2    illustrates an example instrument-alignment interface  200  to provide information regarding a position and/or an orientation of a medical instrument and/or other information regarding a medical procedure in accordance with one or more embodiments. As shown, the instrument-alignment interface  200  (sometimes referred to as “the instrument-alignment graphical user interface (GUI)  200 ”) can include a scope section  210  to provide an image(s)  212  captured by a first medical instrument, such as a scope, and an alignment section  220  to provide information regarding an orientation of a second medical instrument, such as a needle. Although the scope section  210  and the alignment section  220  are illustrated as being included in the same instrument-alignment interface  200 , in some embodiments the instrument-alignment interface  200  includes only one of the sections  210  and  220 . For example, the alignment section  220  can be included as part of the instrument-alignment interface  200  and the scope section  210  can be included within an additional interface. Further, in some examples, the scope section  210  and/or the alignment section  220  can be implemented within an augmented or virtual reality interface, such as with the alignment section  220  overlaid onto at least a portion of the scope section  212 , with the scope section  212  presented with alignment information in a different form than the alignment section  220 , and so on. In the example of  FIG.  2   , the instrument-alignment interface  200  provides information for a procedure that uses a scope and another medical instrument. However, the instrument-alignment interface  200  can be used for other types of procedures, such as a procedure that is performed without a scope. In such cases, the image(s)  212  may not be presented and/or the scope section  210  may be eliminated. 
     As noted above, the scope section  212  provides the image(s)  212  for a scope that is configured to navigate within a lumen or other anatomy. In this example, the image(s)  212  depicts an interior portion of a kidney, including cavities  214  and the kidney stone  216  located within one of the cavities  214 . Here, the kidney stone  216  is located within a calyx in proximity to a papilla. However, the image(s)  212  can depict any human anatomy depending on a location of the scope within a patient. The image(s)  212  can include a real-time image, such as a video. 
     The alignment section  220  includes an alignment-progress visualization  230  to indicate an alignment of an orientation of a medical instrument to a target trajectory and/or a proximity of the medical instrument to a target location. As shown, the alignment-progress visualization  230  includes an instrument-alignment element  232  (sometimes referred to as “the instrument-alignment icon  232 ” or “the needle-alignment icon  232 ”) representing the orientation of the medical instrument and alignment markings  234  associated with the target trajectory. In this example, the instrument-alignment element  232  can move within an area defined by the alignment marking  234 (C) (also referred to as “the boundary marking  234 (C)”) based on a change in the orientation of the medical instrument. For instance, as the medical instrument is tilted, the instrument-alignment element  232  can change position within the area. In examples, the alignment marking  234 (A) can represent a target location/trajectory/pose. 
     In some embodiments, a tilt of the medical instrument in one direction will cause movement of the instrument-alignment element  232  in the opposite direction, similar to a bull&#39;s-eye spirit type of level. For example, if the medical instrument is tilted to the right, the instrument-alignment element  232  can move to the left. In other embodiments, a tilt of the medical instrument will cause movement of the instrument-alignment element  232  in the same direction of the tilt. For example, if the medical instrument is tilted to the right, the instrument-alignment element  232  can move to the right. In any event, when the orientation of the medical instrument is aligned with the target trajectory, the instrument alignment element  232  can be displayed in an aligned arrangement with the alignment markings  234  (e.g., centered with the alignment markings  234 , such as within or centered on the alignment marking  234 (A)). 
     In some embodiments, an amount of position change of the instrument-alignment element  232  for a unit of orientation change of a medical instrument (e.g., a sensitivity of the instrument-alignment element  232 ) is based on a proximity of the medical instrument to a target location. For example, as the medical instrument moves closer to the target location, the instrument alignment element  232  can be implemented with larger or smaller movements for a same amount of change in the orientation of the medical instrument. To illustrate, when the medical instrument is a first distance from the target location, the instrument-alignment interface  200  can change a position of the instrument-alignment element  232  by a first amount in response to a unit of change of an orientation of the medical instrument. When the medical instrument is a second distance from the target location (e.g., closer to the target location), the instrument-alignment interface  200  can change a position of the instrument-alignment element  232  by a second amount (e.g., a larger or smaller amount) in response to the same unit of change of the orientation of the medical instrument. 
     In some embodiments, changing the sensitivity of the instrument-alignment element  232  can further assist a physician in reaching a target location with a medical instrument. For example, in some cases, as a medical instrument is farther from a target, less precision can be needed to orient the medical instrument. While as the medical instrument moves closer to the target location, more precision can be required to orient the medical instrument. In other words, as the medical instrument moves closer to the target, the physician may need to adjust the orientation of the medical instrument more precisely to actually reach the target. As such, by changing the sensitivity of the instrument-alignment element  232 , a physician can more accurately maneuver the medical instrument to reach a target location, which can be relatively small. 
     The alignment-progress visualization  230  can also include a progress bar  236  to indicate a proximity of a medical instrument to a target location. In the example of  FIG.  2   , the progress bar  236  is presented around the boundary marking  234 (C). However, the progress bar  236  can be presented at any location within the instrument-alignment interface  200 , such as to the side of the alignment-progress visualization  230 . The progress bar  236  can provide current position information for the medical instrument relative to the target location. For example, the progress bar  236  can fill in as the medical instrument moves closer to the target location, as discussed in examples below. In some embodiments, if the medical instrument has reached the target location, the instrument-alignment interface  200  can provide an indication that the medical instrument has reached the target location, such as with an indication on the progress bar  236 . In a similar manner, in some embodiments, if the medical instrument is inserted beyond the target location, the instrument-alignment interface  200  can provide an indication that the medical instrument has been inserted beyond the target location, such as with an indication on the progress bar  236 . In the example of  FIG.  2   , the progress bar  236  indicates that the medical instrument has not yet been inserted into a patient (e.g., the medical instrument is on the skin of the patient or otherwise external to the patient). 
     In some embodiments, the alignment-progress visualization  230  includes a single visualization to view orientation and progress information regarding a medical instrument. For example, information regarding an orientation of the medical instrument and a progress of the instrument to a target location can be displayed in a combined visualization. Such combined visualization can allow a physician or other user to maintain visual contact with a single item while manipulating the medical instrument and avoid inadvertent movements of the medical instrument that can occur due to movement of the physician&#39;s eyes or body to view several displays, interfaces, visualizations, etc. As such, the combined visualization can allow the physician or other user to more accurately manipulate the medical instrument to reach a target location within the patient. 
     In the example of  FIG.  2   , various components of the alignment-progress visualization  230  are presented with circular shapes. However, any component of the alignment-progress visualization  230  can take a variety of forms, such as any other shape. For example, the alignment markings  234 , the instrument-alignment element  232 , and/or the progress bar  236  can be presented with a rectangular shape or any other shape. In some implementations, the instrument-alignment element  232  includes a bubble representation representing an air bubble. 
     As also shown in  FIG.  2   , the instrument-alignment interface  200  can include navigation representations  240  to navigate between different visualizations associated with different phases/steps of a procedure. For example, a procedure associated with removing a kidney stone can include a variety of phases/steps, with one of the phases/steps including aligning and inserting the medical instrument into the patient to reach a target location. For such phase/step, the instrument-alignment interface  200  can display the information shown in  FIG.  2    to assist the physician in performing such phase/step. The physician can move to a different visualization or interface for a previous or next phase/step by selecting the “back” or “next” text within the navigation representations  240 . Further, the instrument-alignment interface  200  can include a visual representation  250  to access a menu, which can enable access to interfaces/information associated with other types of procedures or other information. 
     Although many embodiments are discussed and illustrated in the context of an instrument-alignment interface including two-dimensional (2D) representations, an instrument-alignment interface can include three-dimensional (3D) representations in some embodiments. For example, an instrument-alignment interface can present a plane and distorted lines on the plane to indicate misalignment, present a plane with a shape/form of the plane being configured to distort/change to indicate misalignment, and so on. 
     In some embodiments, the instrument-alignment interface  200  and/or any other interface discussed herein is based on targeting data and/or interface data. For example, targeting/interface data can be generated that indicates a projected position of a medical instrument on a plane relative to a target location on the plane. The target/interface data can be used to display the alignment-progress visualization  230 , such as to position the instrument-alignment element  232  representing the orientation of the medical instrument relative to the alignment markings  234  associated with the target trajectory. 
     Example Procedure Using a Medical System 
       FIGS.  3 - 5    illustrate a top view the medical system  100  of  FIG.  1    arranged to perform a percutaneous procedure in accordance with one or more embodiments. In these examples, the medical system  100  is arranged in an operating room to remove a kidney stone from the patient  130  with the assistance of the scope  120  and the needle  170 . In many embodiments of such procedure, the patient  130  is positioned in a modified supine position with the patient  130  slightly tilted to the side to access the back or side of the patient  130 , such as that illustrated in  FIG.  1   . However, the patient  130  can be positioned in other manners, such as a supine position, a prone position, and so on. For ease of illustration in viewing the anatomy of the patient  130 ,  FIG.  3 - 5    illustrate the patient  130  in a supine position with the legs spread apart. Also, for ease of illustration, the imaging device  190  (including the C-arm) has been removed. 
     Although  FIGS.  3 - 5    illustrate use of the medical system  100  to perform a percutaneous procedure to remove a kidney stone from the patient  130 , the medical system  100  can be used to remove a kidney stone in other manners and/or to perform other procedures. Further, the patient  130  can be arranged in other positions as desired for a procedure. Various acts are described in  FIGS.  3 - 5    and throughout this disclosure as being performed by the physician  160 . It should be understood that these acts can be performed directly by the physician  160 , a user under direction of the physician, another user (e.g., a technician), a combination thereof, and/or any other user. 
     The renal anatomy, as illustrated at least in part in  FIGS.  3 - 5   , is described here for reference with respect to certain medical procedures relating to aspects of the present concepts. The kidneys generally comprise two bean-shaped organs located on the left and right in the retroperitoneal space. In adult humans, the kidneys are generally about 11 cm in length. The kidneys receive blood from the paired renal arteries; blood exits into the paired renal veins. Each kidney is attached to a ureter, which is a tube that carries excreted urine from the kidney to the bladder. The bladder is attached to the urethra. 
     The kidneys are typically located relatively high in the abdominal cavity and lie in a retroperitoneal position at a slightly oblique angle. The asymmetry within the abdominal cavity, caused by the position of the liver, typically results in the right kidney being slightly lower and smaller than the left, and being placed slightly more to the middle than the left kidney. On top of each kidney is an adrenal gland. The upper parts of the kidneys are partially protected by the 11th and 12th ribs. Each kidney, with its adrenal gland is surrounded by two layers of fat: the perirenal fat present between renal fascia and renal capsule and pararenal fat superior to the renal fascia. 
     The kidney participates in the control of the volume of various body fluid compartments, fluid osmolality, acid-base balance, various electrolyte concentrations, and removal of toxins. The kidneys provide filtration functionality by secreting certain substances and reabsorbing others. Examples of substances secreted into the urine are hydrogen, ammonium, potassium, and uric acid. In addition, the kidneys also carry out various other functions, such as hormone synthesis, and others. 
     A recessed area on the concave border of the kidney is the renal hilum, where the renal artery enters the kidney and the renal vein and ureter leave. The kidney is surrounded by tough fibrous tissue, the renal capsule, which is itself surrounded by perirenal fat, renal fascia, and pararenal fat. The anterior (front) surface of these tissues is the peritoneum, while the posterior (rear) surface is the transversalis fascia. 
     The functional substance, or parenchyma, of the kidney is divided into two major structures: the outer renal cortex and the inner renal medulla. These structures take the shape of a plurality of cone-shaped renal lobes, each containing renal cortex surrounding a portion of medulla called a renal pyramid. Between the renal pyramids are projections of cortex called renal columns. Nephrons, the urine-producing functional structures of the kidney, span the cortex and medulla. The initial filtering portion of a nephron is the renal corpuscle, which is located in the cortex. This is followed by a renal tubule that passes from the cortex deep into the medullary pyramids. Part of the renal cortex, a medullary ray is a collection of renal tubules that drain into a single collecting duct. 
     The tip, or papilla, of each pyramid empties urine into a respective minor calyx; minor calyces empty into major calyces, and major calyces empty into the renal pelvis, which transitions to the ureter. At the hilum, the ureter and renal vein exit the kidney and the renal artery enters. Hilar fat and lymphatic tissue with lymph nodes surrounds these structures. The hilar fat is contiguous with a fat-filled cavity called the renal sinus. The renal sinus collectively contains the renal pelvis and calyces and separates these structures from the renal medullary tissue. 
       FIGS.  3 - 5    show various features of the anatomy of the patient  130 . For example, the patient  130  includes kidneys  310  fluidly connected to a bladder  330  via ureters  320 , and a urethra  340  fluidly connected to the bladder  330 . As shown in the enlarged depiction of the kidney  310 (A), the kidney  310 (A) includes calyces (including calyx  312 ), renal papillae (including the renal papilla  314 , also referred to as “the papilla  314 ”), and renal pyramids (including the renal pyramid  316 ). In these examples, a kidney stone  318  is located in proximity to the papilla  314 . However, the kidney stone  318  can be located at other locations within the kidney  310 (A) or elsewhere. 
     As shown in  FIG.  3   , to remove the kidney stone  318  in the example percutaneous procedure, the physician  160  can position the robotic system  110  at the side/foot of the table  150  to initiate delivery of the scope  120  (not illustrated in  FIG.  3   ) into the patient  130 . In particular, the robotic system  110  can be positioned at the side of the table  150  within proximity to the feet of the patient  130  and aligned for direct linear access to the urethra  340  of the patient  130 . In examples, the hip of the patient  130  is used as a reference point to position the robotic system  110 . Once positioned, one or more of the robotic arms  112 , such as the robotic arms  112 (B) and  112 (C), can stretch outwards to reach in between the legs of the patient  130 . For example, the robotic arm  112 (B) can be controlled to extend and provide linear access to the urethra  340 , as shown in  FIG.  3   . In this example, the physician  160  inserts a medical instrument  350  at least partially into the urethra  340  along this direct linear access path (sometimes referred to as “a virtual rail”). The medical instrument  350  can include a lumen-type device configured to receive the scope  130 , thereby assisting in inserting the scope  120  into the anatomy of the patient  130 . By aligning the robotic arm  112 (B) to the urethra  340  of the patient  130  and/or using the medical instrument  350 , friction and/or forces on the sensitive anatomy in the area can be reduced. Although the medical instrument  350  is illustrated in  FIG.  3   , in some embodiments, the medical instrument  350  is not used (e.g., the scope  120  can be inserted directly into the urethra  340 ). 
     The physician  160  can also position the robotic arm  112 (A) near a treatment site for the procedure. For example, the robotic arm  112 (A) can be positioned within proximity to the incision site and/or the kidneys  310  of the patient  130 . The robotic arm  112 (A) can be connected to the EM field generator  180  to assist in tracking a location of the scope  120  and/or the needle  170  during the procedure. Although the robotic arm  112 (A) is positioned relatively close to the patient  130 , in some embodiments the robotic arm  112 (A) is positioned elsewhere and/or the EM field generator  180  is integrated into the table  150  (which can allow the robotic arm  112 (A) to be in a docked position). In this example, at this point in the procedure, the robotic arm  112 (C) remains in a docked position, as shown in  FIG.  3   . However, the robotic arm  112 (C) can be used in some embodiments to perform any of the functions discussed above of the robotic arms  112 (A) and/or  112 (C). 
     Once the robotic system  110  is properly positioned and/or the medical instrument  350  is inserted at least partially into the urethra  340 , the scope  120  can be inserted into the patient  130  robotically, manually, or a combination thereof, as shown in  FIG.  4   . For example, the physician  160  can connect the scope  120  to the robotic arm  112 (C) and/or position the scope  120  at least partially within the medical instrument  350  and/or the patient  130 . The scope  120  can be connected to the robotic arm  112 (C) at any time, such as before the procedure or during the procedure (e.g., after positioning the robotic system  110 ). The physician  160  can then interact with the control system  140 , such as the I/O device(s)  146 , to navigate the scope  120  within the patient  130 . For example, the physician  160  can provide input via the I/O device(s)  146  to control the robotic arm  112 (C) to navigate the scope  120  through the urethra  340 , the bladder  330 , the ureter  320 (A), and up to the kidney  310 (A). 
     As shown, the control system  140  can present an instrument-alignment interface  410 , such as the instrument-alignment interface  200  of  FIG.  2   , via the display(s)  142  to view a real-time image  412  captured by the scope  120  to assist the physician  160  in controlling the scope  120 . The physician  160  can navigate the scope  120  to locate the kidney stone  318 , as depicted in the image  412 . In some embodiment, the control system  140  can use localization techniques to determine a position and/or an orientation of the scope  120 , which can be viewed by the physician  160  through the display(s)  142  (not illustrated on the display(s)  142  in  FIG.  4   ) to also assist in controlling the scope  120 . Further, in some embodiments, other types of information can be presented through the display(s)  142  to assist the physician  160  in controlling the scope  120 , such as x-ray images of the internal anatomy of the patient  130 . 
     Upon locating the kidney stone  318 , the physician  160  can identify a location for the needle  170  to enter the kidney  310 (A) for eventual extraction of the kidney stone  318 . For example, to minimize bleeding and/or avoid hitting a blood vessel or other undesirable anatomy of the kidney  310 (A) and/or anatomy surrounding the kidney  310 (A), the physician  160  can seek to align the needle  170  with an axis of a calyx (e.g., can seek to reach the calyx head-on through the center of the calyx). To do so, the physician  160  can identify a papilla as a target location. In this example, the physician  160  uses the scope  120  to locate the papilla  314  that is near the kidney stone  318  and designate the papilla  314  as the target location. In some embodiments of designating the papilla  314  as the target location, the physician  160  can navigate the scope  120  to contact the papilla  314 , the control system  140  can use localization techniques to determine a location of the scope  120  (e.g., a location of the end of the scope  120 ), and the control system  140  can associate the location of the scope  120  with the target location. In other embodiments, the physician  160  can navigate the scope  120  to be within a particular distance to the papilla  314  (e.g., park in front of the papilla  314 ) and provide input indicating that the target location is within a field-of-view of the scope  120 . The control system  140  can perform image analysis and/or other localization techniques to determine a location of the target location. In yet other embodiments, the scope  120  can deliver a fiduciary to mark the papilla  314  as the target location. 
     As shown in  FIG.  5   , the physician  160  can proceed with the procedure by positioning the needle  170  for insertion into the target location. In some embodiments, the physician  160  can use his or her best judgment to place the needle  170  on the patient  130  at an incision site, such as based on knowledge regarding the anatomy of the patient  130 , experience from previously performing the procedure, an analysis of CT/x-ray images or other pre-operative information of the patient  130 , and so on. Further, in some embodiments, the control system  140  can provide information regarding a location to place the needle  170  on the patient  130 . The physician  160  can attempt to avoid critical anatomy of the patient  130 , such as the lungs, pleura, colon, paraspinal muscles, ribs, intercostal nerves, etc. In some examples, the control system  140  can use CT/x-ray/ultrasound images to provide information regarding a location to place the needle  170  on the patient  130 . 
     In any event, the control system  140  can determine a target trajectory  502  for inserting the needle  170  to assist the physician  160  in reaching the target location (i.e., the papilla  314 ). The target trajectory  502  can represent a desired path for accessing to the target location. The target trajectory  502  can be determined based on a position of a medical instrument (e.g., the needle  170 , the scope  120 , etc.), a target location within the human anatomy, a position and/or orientation of a patient, the anatomy of the patient (e.g., the location of organs within the patient relative to the target location), and so on. In this example, the target trajectory  502  includes a straight line that passes through the papilla  314  and the needle  170  (e.g., extends from a tip of the needle  170  through the papilla  314 , such as a point on an axis of the papilla  314 ). However, the target trajectory  502  can take other forms, such as a curved line, and/or can be defined in other manners. In some examples, the needle  170  is implemented a flexible bevel-tip needle that is configured to curve as the needle  170  is inserted in a straight manner. Such needle can be used to steer around particular anatomy, such as the ribs or other anatomy. Here, the control system  140  can provide information to guide a user, such as to compensate for deviation in the needle trajectory or to maintain the user on the target trajectory. 
     Although the example of  FIG.  5    illustrates the target trajectory  502  extending coaxially through the papilla  314 , the target trajectory  502  can have another position, angle, and/or form. For example, a target trajectory can be implemented with a lower pole access point, such as through a papilla located below the kidney stone  318  shown in  FIG.  5   , with a non-coaxial angle through the papilla, which can be used to avoid the hip. 
     The control system  140  can use the target trajectory  502  to provide an alignment-progress visualization  504  via the instrument-alignment interface  410 . For example, the alignment-progress visualization  504  can include an instrument alignment element  506  indicative of an orientation of the needle  170  relative to the target trajectory  502 . The physician  160  can view the alignment-progress visualization  504  and orient the needle  170  to the appropriate orientation (i.e., the target trajectory  502 ). When aligned, the physician  160  can insert the needle  170  into the patient  130  to reach the target location. The alignment-progress visualization  504  can provide a progress visualization  508  (also referred to as “the progress bar  508 ”) indicative of a proximity of the needle  170  to the target location. As such, the instrument-alignment interface  410  can assist the physician  160  in aligning and/or inserting the needle  170  to reach the target location. 
     Once the target location has been reached with the needle  170 , the physician  160  can insert another medical instrument, such as a power catheter, vacuum, nephroscope, etc., into the path created by the needle  170  and/or over the needle  170 . The physician  160  can use the other medical instrument and/or the scope  120  to fragment and remove pieces of the kidney stone  318  from the kidney  310 (A). 
     In some embodiments, a position of a medical instrument can be represented with a point/point set and/or an orientation of the medical instrument can be represented as an angle/offset relative to an axis/plane. For example, a position of a medical instrument can be represented with a coordinate(s) of a point/point set within a coordinate system (e.g., one or more X, Y, Z coordinates) and/or an orientation of the medical instrument can be represented with an angle relative to an axis/plane for the coordinate system (e.g., angle with respect to the X-axis/plane, Y-axis/plane, and/or Z-axis/plane). Here, a change in orientation of the medical instrument can correspond to a change in an angle of the medical instrument relative to the axis/plane. Further, in some embodiments, an orientation of a medical instrument is represented with yaw, pitch, and/or roll information. 
     In some embodiments, a trajectory refers as a pose. For example, a trajectory of a medical instrument can refer to a pose of the medical instrument, including/indicating both a position and orientation of the medical instrument. Similarly, a target trajectory can refer to a target pose, including/indicating both a position and orientation of a desired path. However, in other embodiments, a trajectory refers to either an orientation or a position. 
     Although particular robotic arms of the robotic system  110  are illustrated as performing particular functions in the context of  FIGS.  3 - 5   , any of the robotic arms  112  can be used to perform the functions. Further, any additional robotic arms and/or systems can be used to perform the procedure. Moreover, the robotic system  110  can be used to perform other parts of the procedure. For example, the robotic system  110  can be controlled to align and/or insert the needle into the patient  130 . To illustrate, one of the robotic arms  112  can engage with and/or control the needle  170  to position the needle  170  at the appropriate location, align the needle  170  with the target trajectory, and/or insert the needle  170  to the target location. The control system  140  can use localization techniques to perform such processing. As such, in some embodiments, a percutaneous procedure can be performed entirely or partially with the medical system  100  (e.g., with or without the assistance of the physician  160 ). 
     Example Instrument Visualizations 
       FIGS.  6 - 1  through  6 - 11    illustrate example interfaces to provide information regarding an alignment and/or a progress of a medical instrument during a procedure in accordance with one or more embodiments. The example interfaces are illustrated in the context of using the medical system  100  to remove a kidney stone  662  from the patient  130 . In particular, visualizations can be provided to assist the physician  160  in inserting the needle  170  into the patient  130  to extract the kidney stone  662 . However, the visualizations can be displayed for use with other medical systems and/or to perform other medical procedures. For ease of illustration, some features of the interfaces are not illustrated in each of  FIGS.  6 - 1  through  6 - 11   . For example, alignment markings  634 (B) are not illustrated in  FIGS.  6 - 2  through  6 - 11   . 
       FIG.  6 - 1    illustrates the example instrument-alignment interface  600  with visualizations to assist the physician  160  in aligning the needle  170  with a target trajectory  670 . As shown, the instrument-alignment interface  600  can include a scope section  610  to provide an image(s)  612  captured by the scope  120  that is located within a kidney  660  of the patient  130 , and an alignment section  620  to provide information regarding an orientation and/or position of the needle  170 . Here, the image(s)  612  depicts an internal portion of the kidney  660  and the kidney stone  662  located within the kidney  660 . The alignment section  620  includes an alignment-progress visualization  630  to indicate an alignment of an orientation of the needle  170  to the target trajectory  670  and/or a proximity of the needle  170  to a target location  664  (e.g., a location on a papilla). As shown, the alignment-progress visualization  630  includes an instrument-alignment element  632  representing the orientation of the needle  170  relative to the target trajectory  670  and alignment markings  634  representing the target trajectory  670 , and a progress bar  636  (also referred to as “the progress representation  636 ”) indicating a proximity of the needle  170  to the target location  664 . The instrument-alignment interface  600  can also include navigation representations  640  to navigate between different visualizations associated with different phases/steps of a procedure and/or a visual representation  650  to access a menu and/or other options. Although the instrument-alignment element  632  and the alignment markings  634  are illustrated with particular shapes and sizes, the instrument-alignment element  632  and the alignment markings  634  can have other shapes and/or sizes. 
     In the example of  FIG.  6 - 1   , the physician positions the needle  170  on the patient  130  and attempts to align the needle  170  with the target trajectory  670  using the instrument-alignment interface  600 . In particular, the physician  160  can use one or more hands  680  to hold the needle  170  and adjust an orientation of the needle  170  (e.g., a tilt of the needle  170 ) while viewing the instrument-alignment interface  600  via the control system  140 . Here, the orientation of the needle  170  is out of alignment with the target trajectory  670 . As such, the instrument-alignment interface  600  illustrates the instrument-alignment element  632  as being out of alignment with the center alignment marking  634 (A) (e.g., the instrument-alignment element  632  is not located within the center alignment marking  634 (A)). 
     In some embodiments, the instrument-alignment element  632  can move within the area of the boundary alignment marking  634 (C) (e.g., within the constraints of the boundary alignment marking  634 (C)). The instrument alignment element  632  can move closer to the boundary alignment marking  634 (C) as the needle  170  is less aligned with the target trajectory  670  and move closer to the center alignment marking  634 (A) as the needle  170  is more aligned with the target trajectory  670 . In the example of  FIG.  6 - 1   , the instrument-alignment interface  600  also provides text “Tilt the needle to move bubble to center” indicating that the needle  170  is out of alignment with the target trajectory  670 . The visualizations of the instrument-alignment interface  600  can assist the physician  160  in tilting the needle  170  to align the needle  170  with the appropriate orientation for insertion of the needle  170  to the target location  664 . 
     In some embodiments, if the needle  170  is substantially out of alignment with the target trajectory  670 , the instrument-alignment element  632  can provide an indication of such out-of-alignment configuration, as shown in  FIG.  6 - 2   . For example, if the needle  170  is out of alignment with the target trajectory  670  by more than a threshold amount (e.g., misalignment threshold), the progress bar  636  can be highlighted, outlined, and/or partially/completely filled-in with a particular color/fill pattern to provide such out-of-alignment indication, as shown. To illustrate, the progress bar  636  can be filled-in with a red color (e.g., a closed red ring). Additionally or alternatively, in some embodiments, the instrument-alignment element  632  can be displayed in contact with the boundary marking  634 (C) with a deformed shape, as also shown in  FIG.  6 - 2   . Here, the instrument-alignment element  632  can be displayed in its initial circular form as the instrument-alignment element  632  moves within proximity to the boundary marking  634 (C) and transition to the deformed shape as the needle  170  moves more out of alignment and beyond the misalignment threshold. Such transition visualization can appear similar to an air bubble within a liquid that comes into contact with a surface. Further, in some embodiments, text or another indication can be provided within the instrument-alignment interface  600  to indicate that the needle  170  is out of alignment with the target trajectory by more than the threshold amount. In any case, such out-of-alignment indication can assist the physician  160  in viewing that the needle  170  is substantially off axis with the target trajectory  670 . Although the progress bar  636  is illustrated with particular highlighting, outlining, and/or a fill pattern to provide the substantially out-of-alignment indication in  FIG.  6 - 2   , in some embodiments the progress bar  636  can be implemented without such changes. Here, the instrument-alignment element  632  can be displayed with a deformed shape to provide the substantially out-of-alignment indication. 
     When the needle  170  is aligned with the target trajectory  670 , the instrument-alignment element  632  can be displayed in an aligned manner with the alignment markings  634 , as shown in  FIG.  6 - 3   . For example, the instrument-alignment element  632  can be displayed within and/or concentric with the center alignment marking  634 (A). Additionally or alternatively, the center alignment marking  634 (A) can be highlighted (e.g., with a glow visualization, particular color, etc.) to indicate that the needle  170  is aligned with the target trajectory  670 . Further, the instrument-alignment interface  600  can display text to indicate the alignment, such as text “Aligned,” as shown in  FIG.  6 - 3   . Although the highlighted alignment marking  634 (A) and the text are presented in  FIG.  6 - 3   , in some embodiments just one of such visualizations is presented. Further, other visualizations can be used to indicate such alignment. 
     In in this example, the physician  160  inserts the needle  170  when the needle  170  is aligned with the target trajectory  670 , as shown in  FIGS.  6 - 4  through  6 - 6   . Here, the progress bar  636  provides an indication of the proximity (e.g., a distance) of the needle  170  relative to the target location  664 . In particular, the progress bar  636  can fill-in in a clockwise manner around the boundary marking  634 (C). The control system  140  can determine the proximity of the needle  170  to the target location  664  by using localization techniques to track a position of the needle  170  and/or a position of the target location  664 /the scope  120 . 
     In some embodiments, as the needle  170  moves closer to the target location  664 , an amount of movement of the instrument-alignment element  632  can change (e.g., a sensitivity of the instrument-alignment element  632  can change). For example, the control system  140  can set a position change parameter for the instrument-alignment element  632  to a first value initially when the needle  170  is relatively far from the target location  664  (e.g., outside a distance to the target location  664 ). The position change parameter can be indicative of an amount of position change of the instrument-alignment element  632  with respect to a unit of movement of the needle  170 . As the needle  170  moves closer to the target location  664 , the position change parameter can be updated to a second value, such as a value that is associated with a greater or lesser amount of position change for the same unit of movement of the needle  170  than the first value. 
     In one illustration of updating a position change parameter, when the needle  170  is located on the skin of the patient  130 , the position change parameter can be set to an initial value. The initial value can cause the instrument-alignment element  632  to move by a first number of pixels in response to an orientation change of the needle  170  by 5 degrees, for example. As the needle  170  moves closer to the target location  664 , the position change parameter can be updated to a larger value that causes the instrument-alignment element  632  to move by a second number of pixels in response to an orientation change of the needle  170  by 5 degrees, where the second number of pixels is greater than the first number of pixels. The position change parameter can be updated any number of times as the needle  170  moves closer to the target location  664 . In some embodiments, this can assist the physician in aligning the needle  170  to reach a relatively small target, such as a calyx that can be 4 to 8 mm in diameter. 
     When the needle  170  has reached the target location  664 , the instrument-alignment interface  600  can display an indication that the target location  664  has been reached, as illustrated in  FIG.  6 - 7   . For example, the progress bar  636  can fill-in completely around the perimeter of the boundary marking  634 (C). In some embodiments, the progress bar  636  can be highlighted, outlined, and/or completely filled-in with a particular color/fill pattern to indicate that the target location  664  has been reached. For example, the progress bar  636  can be filled-in with a green color (e.g., a closed green ring). Additionally or alternatively, the instrument-alignment interface  600  can provide text that the target location  664  has been reached, such as providing the text “You reached the target,” as also shown. In some embodiments, as shown in  FIG.  6 - 7   , the image  612  depicting the interior portion of the kidney  660  can also provide a visual confirmation that the needle  170  has reached the target location  664 . 
     In some implementations, if the needle  170  is inserted beyond the target location  664 , the instrument-alignment interface  600  can provide an indication that the needle  170  is inserted beyond the target location  664 , as shown in  FIG.  6 - 8   . For example, the progress bar  636  can be highlighted, outlined, and/or partially/completely filled-in with a particular color/fill pattern to indicate that the needle  170  is inserted beyond the target location  664 . To illustrate, the progress bar  636  can be filled-in with a red color (e.g., a closed red ring) and/or a different color than in the case of the needle  170  being substantially out of alignment (e.g., the case of  FIG.  6 - 2   ). Additionally or alternatively, the instrument-alignment interface  600  can provide text that the needle  170  is inserted beyond the target location  664 , such as providing the text “You inserted beyond the target. Please retract.” In some embodiments, the control system  140  can determine that the needle  170  is inserted beyond the target location  664  when the needle  170  is more than a threshold distance beyond the target location  664  and/or when the needle  170  is within a particular distance to the scope  120 . 
     In some embodiments, as shown in  FIG.  6 - 8   , the image  612  depicting the interior portion of the kidney  660  can also provide a visual confirmation that the needle  170  has been inserted beyond the target location  664 . In other embodiments, a field-of-view of the scope  120  may not include a location where the needle  170  enters the kidney  660  (e.g., the needle  170  can be inserted above or below a field-of-view of the scope  120 ). Here, the progress bar  636  can be particularly helpful in informing the physician  160  that the needle  170  is inserted beyond the target location  664 . 
     In some procedures, once the needle  170  has reached the target location  664 , a medical instrument  638  can be inserted over the needle  170  and/or in the place of the needle  170 , as shown in  FIG.  6 - 9   . The medical instrument  638  can include a device to assist in extracting the kidney stone  662  from the kidney  660 . For example, the medical instrument  638  can include a catheter (e.g., a power catheter), a vacuum tube, a nephroscope, or any other medical instrument. In some embodiments, one or more dilation instruments (e.g., wires, tubes, sheaths, etc.) can be used to dilate a path to the target location  664  to provide sufficient space for insertion of the medical instrument  638 . 
     The medical instrument  638  and/or the scope  120  (and/or the needle  170 , in some cases) can facilitate extraction of the kidney stone  662  from the kidney  660 . For example, the scope  120  can deploy a tool (e.g., a laser, a cutting instrument, etc.) to fragment the kidney stone  662  into pieces and the medical instrument  638  can suck out the pieces from the kidney  660 , as shown in  FIG.  6 - 10   . In some implementations, the scope  120  (and/or the medical instrument  638 ) can provide irrigation to assist in removing the pieces from the kidney  660 . In the example of  FIG.  6 - 10   , the image  612  provides visual confirmation that the kidney stone  662  is being removed from the kidney  660 . 
     In some embodiments, in returning to alignment of the needle  170  on the skin of the patient  130  (e.g.,  FIG.  6 - 2   ), if the needle  170  is inserted when it is substantially out of alignment with the target trajectory  670 , the instrument-alignment interface  600  can provide an indication to retract the needle  170 , as shown in  FIG.  6 - 11   . For example, the control system  140  can determine that the needle is out of alignment with the target trajectory  670  by more than a threshold amount (similar to that discussed in reference to  FIG.  6 - 2   ). Further, the control system  140  can determine that the needle  170  is inserted into the patient  130  beyond a particular distance when the needle  170  is substantially out of alignment with the target trajectory  670 . In some embodiments, the progress bar  636  can be highlighted, outlined, and/or partially/completely filled-in with a particular color/fill pattern to indicate that the needle  170  is inserted and is substantially out of alignment. To illustrate, the progress bar  636  can be filled-in with a red color (e.g., a closed red ring) and/or a different color than the case of the needle  170  just being substantially out of alignment (e.g., the case of  FIG.  6 - 2   ). Additionally or alternatively, in some embodiments, the instrument-alignment interface  600  can provide text that the needle  170  is substantially out of alignment and needs to be retracted, such as providing the text “Retract and reinsert the needle with the appropriate orientation.” In some embodiments, the indication of  FIG.  6 - 11    can be presented when it is determined that there is no adjustment that can be made to the needle  170  to reach the target location  664 . 
     Although alignment and progress information are illustrated with specific indications in  FIGS.  6 - 1  through  6 - 11   , other indications can be provided including audible, visual, haptic, etc. For example, the control system  140  can provide sounds and/or haptic feedback via an I/O device associated with the control system  140  to indicate alignment and/or progress of the needle  170  (e.g., a first sound when the needle  170  is aligned with the target trajectory  670 , a second sound when the needle  170  is initially inserted, a third sound when the needle  170  is halfway to the target trajectory  664 , a third sound when the needle  170  has reached the target location  664 , etc.). Further, any of the indications discussed can be illustrated in different forms (e.g., different shapes, sizes, colors, and so on) and/or presented at different locations within the instrument-alignment interface  600 . 
     In some implementations, the progress bar  636  can include a straight progress bar, instead of the circular bar illustrated around the boundary marking  634 , which can be positioned at any location within the instrument-alignment interface  600 . Further, in some embodiments, instead of filling in the progress bar  636  to indicate a proximity of the needle  170  to the target location  664 , a current position of the needle  170  can be displayed on the progress bar  636  with an icon (e.g., with the icon at a top position indicating that the needle  170  is not yet inserted into the patient  130  and/or has reached the target location  664 ). Moreover, in some embodiments, a percentage of progress to the target location  664  can be presented via the instrument-alignment interface  600 . 
     Furthermore, in some embodiments, a size of the center alignment marking  634 (A), the boundary marking  634 (C), and/or the instrument-alignment element  632  can change to indicate a progress of inserting the needle  170  to the target location  664 . For example, a diameter of the center alignment marking  634 (A) can decrease as the needle  170  is inserted until the center alignment marking  634 (A) reaches the same diameter as the instrument-alignment element  632 . 
     Example Flow Diagrams 
       FIGS.  7 - 10    illustrate example flow diagrams of processes for performing one or more techniques discussed herein. The various operations associated with the processes can be performed by control circuitry implemented in any of the devices/systems discussed herein, or a combination thereof, such as the control system  140 , the robotic system  110 , the table  150 , the EM field generator  180 , the scope  120 , and/or the needle  170 . 
       FIG.  7    illustrates an example flow diagram of a process  700  for determining an alignment of a medical instrument relative to a target trajectory and presenting information regarding the alignment of the medical instrument to the target trajectory in accordance with one or more embodiments. At block  702 , the process  700  can include receiving sensor data from one or more medical instruments. For example, according to certain use cases, control circuitry of a device/system, such as a control system, can receive sensor data via a communication interface from one or more medical instruments, such as a scope, a needle, or any other medical instrument. The sensor data can be indicative of a position and/or an orientation of the one or more medical instruments. 
     At block  704 , the process  700  can include determining a target location within human anatomy. For example, according to certain use cases, control circuitry can determine a target location within a patient, such as an anatomical landmark, a location of a medical instrument, or any other location/target. In some embodiments, the control circuitry can determine the target location based at least in part on sensor data from a medical instrument that is disposed at least partially within the patient. 
     At block  706 , the process  700  can include determining a position and/or an orientation of the one or more medical instruments. For example, according to certain use cases, control circuitry can determine a position and/or an orientation of one or more medical instruments based at least in part on sensor data from the one or more medical instruments. In some embodiments, the control circuitry can use one or more localization techniques to determine the position and/or the orientation of the one or more medical instruments. 
     At block  708 , the process  700  can include determining a target trajectory for accessing the target location. For example, according to certain use cases, control circuitry can determine a target trajectory for accessing a target location within a patient percutaneously. In some embodiments, the control circuitry can determine the target trajectory based at least in part on sensor data from a medical instrument that is disposed at least partially within the patient, sensor data from a medical instrument that is located externally to the patient (or partially inserted), a position of the target location, and so on. Additionally or alternatively, a target trajectory can be determined based on a user providing input through an interface to designate a target trajectory. In examples, a target trajectory can be defined with respect to one or more anatomical planes/axes. 
     At block  710 , the process  700  can include generating user interface data representing an interface that includes an instrument-alignment element indicative of an alignment of an orientation of a medical instrument to the target trajectory. For example, according to certain use cases, control circuitry can generate user interface data representing an interface (e.g., an instrument-alignment interface) that includes an instrument-alignment element representing an orientation of a medical instrument, such as a needle-alignment icon representing an orientation of a needle. In some embodiments, a positioning of the instrument-alignment element within the interface can indicate an alignment of the orientation of the medical instrument to a target trajectory. 
     At block  712 , the process  700  can include causing display of the interface. For example, according to certain use cases, control circuitry can cause display of an interface via a display device, such as by sending user interface data to a display device associated with a control system. Further, according to certain use cases, a display device can display of an interface based at least in part on user interface data. In any case, the interface can include an instrument-alignment element representing an orientation of a medical instrument. 
     At block  714 , the process  700  can include updating a position of the instrument-alignment element based at least in part on a change in the orientation of the medical instrument. For example, according to certain use cases, control circuitry can determine a change to an orientation of a medical instrument and update a position of an instrument-alignment element that is associated with the medical instrument based at least in part on the change in orientation of the medical instrument. 
     In some embodiments of block  714 , control circuitry can update the position of an instrument-alignment element based at least in part on a proximity of a medical instrument to a target location. For example, in response to determining that the orientation of the medical instrument has changed by a unit of measurement and determining that the medical instrument is outside a predetermined proximity to the target location, the control circuitry can update a position of the instrument-alignment element within an interface by a first amount. Further, in response to determining that the orientation of the medical instrument has changed by the unit of measurement and determining that the medical instrument is within the predetermined proximity to the target location, the control circuitry can update the position of the instrument-alignment element within the interface by a second amount. 
       FIG.  8    illustrates an example flow diagram of a process  800  for presenting information regarding an orientation of a medical instrument in accordance with one or more embodiments. At block  802 , the process  800  can include determining an orientation of a medical instrument. For example, according to certain use cases, control circuitry can determine an orientation of a medical instrument that is configured to access a human anatomy percutaneously based at least in part on sensor data from the medical instrument. In some embodiments, the control circuitry can use one or more localization techniques to determine the orientation of the medical instrument. 
     At block  804 , the process  800  can include determining if the orientation of the medical instrument is aligned with a target trajectory. For example, according to certain use cases, control circuitry can determine, based at least in part on sensor data of a medical instrument, whether or not an orientation of the medical instrument is aligned with a target trajectory that is determined for accessing a target location percutaneously. In some embodiments, the control circuitry can compare one or more coordinates and/or angles of the orientation of the medical instrument with one or more coordinates and/or angles of the target trajectory and determine if one or more thresholds are satisfied (e.g., the one or more coordinates and/or angles of the orientation of the medical instrument are within a particular number of coordinates and/or degrees to the one or more coordinates and/or angles of the target trajectory). In examples, alignment can be determined with respect to positional error and/or angular error (e.g., X, Y, Z, yaw, pitch, roll) and/or with respect to any coordinate frame. 
     If it is determined that the orientation of the medical instrument is aligned with the target trajectory, the process  800  can proceed to block  806 . In contrast, if it is determined that the orientation of the medical instrument is not aligned with the target trajectory, the process  800  can proceed to block  808 . 
     At block  806 , the process  800  can include causing display of an indication that the orientation of the medical instrument is aligned with the target trajectory. For example, according to certain use cases, control circuitry can cause display of an indication, within an interface, that an orientation of a medical instrument is aligned with a target trajectory, such as by sending data to a display device associated with a control system. Further, according to certain use cases, a display device can display, within an interface, an indication that an orientation of a medical instrument is aligned with a target trajectory. In some embodiments, an instrument-alignment element is displayed in an aligned arrangement with one or more alignment markings (e.g., centered on a marking) to indicate that the orientation of the medical instrument is aligned with the target trajectory. 
     At block  808 , the process  800  can include determining if the orientation of the medical instrument is out of alignment with the target trajectory by more than a threshold amount. For example, according to certain use cases, control circuitry can determine, based at least in part on sensor data of a medical instrument, whether or not the orientation of the medical instrument is out of alignment with a target trajectory by more than a threshold amount. In some embodiments, the control circuitry can compare one or more coordinates and/or angles of the orientation of the medical instrument with one or more coordinates and/or angles of the target trajectory. 
     If it is determined that the orientation of the medical instrument out of alignment with the target trajectory by more than the threshold amount, the process  800  can proceed to block  810 . In contrast, if it is determined that the orientation of the medical instrument not out of alignment with the target trajectory by more than the threshold amount, the process  800  can proceed to block  812 . 
     At block  810 , the process  800  can include causing display of an instrument-alignment element at a boundary marking and/or with a deformed form. For example, according to certain use cases, control circuitry can cause display of an instrument-alignment element within a predetermined proximity to a boundary marking and/or with a deformed shape, such as by sending data to a display device associated with a control system. Further, according to certain use cases, a display device can display, within an interface, an instrument-alignment element within a predetermined proximity to a boundary marking and/or with a deformed shape. 
     At block  812 , the process  800  can include causing display of an instrument-alignment element with a position that is out of alignment. For example, according to certain use cases, control circuitry can cause display of an instrument-alignment element at a location that is not aligned with an alignment marking, such as by sending data to a display device associated with a control system. Further, according to certain use cases, a display device can display an instrument-alignment element at a location that is not aligned with an alignment marking. 
     At block  814 , the process  800  can include determining if the medical instrument is inserted into the human anatomy. For example, according to certain use cases, control circuitry can determine whether or not a medical instrument is disposed at least partially within a patient based at least in part on sensor data from the medical instrument and/or information regarding a position and/or orientation of the patient. In some embodiments, the control circuitry can determine whether or not the medical instrument is inserted into the patient by a particular amount. 
     If it is determined that the medical instrument is inserted into the human anatomy, the process  800  can proceed to block  816 . In contrast, if it is determined that the medical instrument is not inserted into the human anatomy, the process  800  can proceed to block  818 . 
     At block  816 , the process  800  can include causing display of an indication to retract the medical instrument. For example, according to certain use cases, control circuitry can cause display of an indication to retract a medical instrument, such as by sending data to a display device associated with a control system. Further, according to certain use cases, a display device can display an indication to retract a medical instrument. In some embodiments, control circuitry can maintain display of information associated with blocks  810  and/or  812  (e.g., instrument-alignment elements), as well as provide the indication to retract the medical instrument. 
     At block  818 , the process  800  can include maintaining display of information. For example, according to certain use cases, control circuitry can maintain display of text or other visualizations regarding a current orientation and/or position of a medical instrument (e.g., information presented at blocks  810  and/or  812 ). Although block  818  is illustrated, in some embodiments, another operation or process can be performed. 
       FIG.  9    illustrates an example flow diagram of a process  900  for presenting information regarding a proximity of a medical instrument to a target location in accordance with one or more embodiments. At block  902 , the process  900  can include determining a proximity of a medical instrument to a target location. For example, according to certain use cases, control circuitry can determine a proximity of a medical instrument to a target location within a patient based at least in part on sensor data from the medical instrument. In some embodiments, the control circuitry can use one or more localization techniques to determine the position of the medical instrument. 
     At block  904 , the process  900  can include causing display of an indication of the proximity of the medical instrument to the target location. For example, according to certain use cases, control circuitry can cause display of an indication, within an interface, of a proximity of a medical instrument to a target location, such as by sending data to a display device associated with a control system. Further, according to certain use cases, a display device can display an indication, within an interface, of a proximity of a medical instrument to a target location. 
     At block  906 , the process  900  can include determining if the medical instrument has reached the target location. For example, according to certain use cases, control circuitry can determine whether or not a medical instrument has reached a target location within a patient based at least in part on sensor data from the medical instrument. 
     If it is determined that the medical instrument has reached the target location, the process  900  can proceed to block  908 . In contrast, if it is determined that the medical instrument as not reached the target location, the process  900  can proceed back to block  902 . 
     At block  908 , the process  900  can include causing display of an indication of that the medical instrument has reached the target location. For example, according to certain use cases, control circuitry can cause display of an indication, within an interface, that a medical instrument has reached a target location, such as by sending data to a display device associated with a control system. Further, according to certain use cases, a display device can display an indication, within an interface, that a medical instrument has reached a target location. 
     At block  910 , the process  900  can include determining if the medical instrument is inserted beyond the target location. For example, according to certain use cases, control circuitry can determine, whether or not a medical instrument is inserted beyond the target location based at least in part on sensor data from the medical instrument. 
     If it is determined that the medical instrument is inserted beyond the target location, the process  900  can proceed to block  912 . In contrast, if it is determined that the medical instrument is not inserted beyond the target location, the process  900  can proceed back to block  902 . Although the process  900  is illustrated as proceeding back to block  902  in the example of  FIG.  9   , in some embodiments, the process  900  can proceed back to block  906 , block  908 , or another block. 
     At block  912 , the process  900  can include causing display of an indication of that the medical instrument is inserted beyond the target location. For example, according to certain use cases, control circuitry can cause display of an indication, within an interface, that a medical instrument is inserted beyond the target location, such as by sending data to a display device associated with a control system. Further, according to certain use cases, a display device can display an indication, within an interface, that a medical instrument is inserted beyond the target location. The process  900  can then proceed back to block  902 . 
       FIG.  10    illustrates an example flow diagram of a process  1000  for setting and/or updating a position change parameter associated with an instrument-alignment element in accordance with one or more embodiments. At block  1002 , the process  1000  can include setting a position change parameter associated with a unit of movement of a medical instrument. For example, according to certain use cases, control circuitry can set a position change parameter to an initial value that is indicative of a particular amount of position change of the instrument-alignment element. The position change parameter can be indicative of an amount of position change of the instrument-alignment element within the interface with respect to a unit of movement of the medical instrument (e.g., a unit of orientation change). In some embodiments, the initial value includes a predetermined or default value that is associated with the medical instrument being located externally to a patient and/or outside a predetermined proximity to a target location. For example, the position change parameter can be set to the initial value when the medical instrument is being aligned before insertion of the medical instrument into the patient. 
     At block  1004 , the process  1000  can include using the position change parameter to change a position of an instrument-alignment element based at least in part on a change in an orientation of the medical instrument. For example, according to certain use cases, control circuitry can determine that an orientation of a medical instrument has changed and, in response, use a position change parameter to change a position of an instrument-alignment element (e.g., use a value of the position change parameter to identify an amount of position change to apply to the instrument-alignment element). 
     At block  1006 , the process  1000  can include determining if the medical instrument is closer to a target location. For example, according to certain use cases, control circuitry can determine whether or not a medical instrument is closer to a target location in comparison to a last position of the medical instrument. Such determination can be based at least in part on sensor data from the medical instrument. In some embodiments, the control circuitry can determine if the medical instrument is within a predetermined proximity to the target location. 
     If it is determined that the medical instrument it is closer to the target location, the process  1000  can proceed to block  1008 . In contrast, if it is determined that the medical instrument it is not closer to the target location, the process  1000  can proceed back to block  1004  and continue to use the previously set position change parameter. 
     At block  1008 , the process  1000  can include updating the position change parameter. For example, according to certain use cases, control circuitry can update a position change parameter to another value that is associated with more or less position change for a unit of movement of a medical instrument. In some embodiments, block  1008  can be implemented in any number of times to update the position change parameter one or more times as the medical instrument moves closer to the target location. Further, in some embodiments, block  1008  can be implemented once when the medical instrument is within a predetermined proximity to the target location. Here, the process  1000  may not return to block  1004  after implementing block  1008 . 
     Example Robotic System 
       FIG.  11    illustrates example details of the robotic system  110  in accordance with one or more embodiments. In this example, the robotic system  110  is illustrated as a cart-based robotically-enabled system that is movable. However, the robotic system  110  can be implemented as a stationary system, integrated into a table, and so on. 
     The robotic system  110  can include the support structure  114  including an elongated section  114 (A) (sometimes referred to as “the column  114 (A)”) and a base  114 (B). The column  114 (A) can include one or more carriages, such as a carriage  1102  (alternatively referred to as “the arm support  1102 ”) for supporting the deployment of one or more the robotic arms  112  (three shown in  FIG.  11   ). The carriage  1102  can include individually configurable arm mounts that rotate along a perpendicular axis to adjust the base of the robotic arms  112  for positioning relative to a patient. The carriage  1102  also includes a carriage interface  1104  that allows the carriage  1102  to vertically translate along the column  114 (A). The carriage interface  1104  is connected to the column  114 (A) through slots, such as slot  1106 , that are positioned on opposite sides of the column  114 (A) to guide the vertical translation of the carriage  1102 . The slot  1106  includes a vertical translation interface to position and hold the carriage  1102  at various vertical heights relative to the base  114 (B). Vertical translation of the carriage  1102  allows the robotic system  110  to adjust the reach of the robotic arms  112  to meet a variety of table heights, patient sizes, physician preferences. etc. Similarly, the individually configurable arm mounts on the carriage  1102  allow a robotic arm base  1108  of the robotic arms  112  to be angled in a variety of configurations. The column  114 (A) can internally comprise mechanisms, such as gears and/or motors, that are designed to use a vertically aligned lead screw to translate the carriage  1102  in a mechanized fashion in response to control signals generated in response to user inputs, such as inputs from the I/O device(s)  116 . 
     In some embodiments, the slot  1106  can be supplemented with a slot cover(s) that is flush and/or parallel to the slot surface to prevent dirt and/or fluid ingress into the internal chambers of the column  114 (A) and/or the vertical translation interface as the carriage  1102  vertically translates. The slot covers can be deployed through pairs of spring spools positioned near the vertical top and bottom of the slot  1106 . The covers can be coiled within the spools until deployed to extend and retract from their coiled state as the carriage  1102  vertically translates up and down. The spring-loading of the spools can provide force to retract the cover into a spool when the carriage  1102  translates towards the spool, while also maintaining a tight seal when the carriage  1102  translates away from the spool. The covers can be connected to the carriage  1102  using, for example, brackets in the carriage interface  1104  to ensure proper extension and retraction of the covers as the carriage  1102  translates. 
     The base  114 (B) can balance the weight of the column  114 (A), the carriage  1102 , and/or arms  112  over a surface, such as the floor. Accordingly, the base  114 (B) can house heavier components, such as one or more electronics, motors, power supply, etc., as well as components that enable movement and/or immobilize the robotic system  110 . For example, the base  114 (B) can include rollable wheels  1116  (also referred to as “the casters  1116 ”) that allow for the robotic system  110  to move around the room for a procedure. After reaching an appropriate position, the casters  1116  can be immobilized using wheel locks to hold the robotic system  110  in place during the procedure. As shown, the robotic system  110  also includes a handle  1118  to assist with maneuvering and/or stabilizing the robotic system  110 . 
     The robotic arms  112  can generally comprise robotic arm bases  1108  and end effectors  1110 , separated by a series of linkages  1112  that are connected by a series of joints  1114 . Each joint  1114  can comprise an independent actuator and each actuator can comprise an independently controllable motor. Each independently controllable joint  1114  represents an independent degree of freedom available to the robotic arm  112 . For example, each of the arms  112  can have seven joints, and thus, provide seven degrees of freedom. However, any number of can be implemented with any degrees of freedom. In examples, a multitude of can result in a multitude of degrees of freedom, allowing for “redundant” degrees of freedom. Redundant degrees of freedom allow the robotic arms  112  to position their respective end effectors  1110  at a specific position, orientation, and/or trajectory in space using different linkage positions and/or joint angles. In some embodiments, the end effectors  1110  can be configured to engage with and/or control a medical instrument, a device, an object, and so on. The freedom of movement of the arms  112  can allow the robotic system  110  to position and/or direct a medical instrument from a desired point in space and/or allow a physician to move the arms  112  into a clinically advantageous position away from the patient to create access, while avoiding arm collisions. 
     As shown in  FIG.  11   , the robotic system  110  can also include the I/O device(s)  116 . The I/O device(s)  116  can include a display, a touchscreen, a touchpad, a projector, a mouse, a keyboard, a microphone, a speaker, a controller, a camera (e.g., to receive gesture input), or another I/O device to receive input and/or provide output. The I/O device(s)  116  can be configured to receive touch, speech, gesture, or any other type of input. The I/O device(s)  116  can be positioned at the vertical end of column  114 (A) (e.g., the top of the column  114 (A)) and/or provide a user interface for receiving user input and/or for providing output. For example, the I/O device(s)  116  can include a touchscreen (e.g., a dual-purpose device) to receive input and provide a physician with pre-operative and/or intra-operative data. Example pre-operative data can include pre-operative plans, navigation, and/or mapping data derived from pre-operative computerized tomography (CT) scans, and/or notes from pre-operative patient interviews. Example intra-operative data can include optical information provided from a tool/instrument, sensor, and/or coordinate information from sensors, as well as vital patient statistics, such as respiration, heart rate, and/or pulse. The I/O device(s)  116  can be positioned and/or tilted to allow a physician to access the I/O device(s)  116  from a variety of positions, such as the side of the column  114 (A) opposite the carriage  1102 . From this position, the physician can view the I/O device(s)  116 , the robotic arms  112 , and/or a patient while operating the I/O device(s)  116  from behind the robotic system  110 . 
     The robotic system  110  can include a variety of other components. For example, the robotic system  110  can include one or more control electronics/circuitry, power sources, pneumatics, optical sources, actuators (e.g., motors to move the robotic arms  112 ), memory, and/or communication interfaces (e.g. to communicate with another device). In some embodiments, the memory can store computer-executable instructions that, when executed by the control circuitry, cause the control circuitry to perform any of the operations discussed herein. For example, the memory can store computer-executable instructions that, when executed by the control circuitry, cause the control circuitry to receive input and/or a control signal regarding manipulation of the robotic arms  112  and, in response, control the robotic arms  112  to be positioned in a particular arrangement and/or to navigate a medical instrument connected to the end effectors  1110 . 
     In some embodiments, robotic system  110  is configured to engage with and/or control a medical instrument, such as the scope  120 . For example, the robotic arms  112  can be configured to control a position, orientation, and/or tip articulation of a scope (e.g., a sheath and/or a leader of the scope). In some embodiments, the robotic arms  112  can be configured/configurable to manipulate the scope  120  using elongate movement members. The elongate movement members can include one or more pull wires (e.g., pull or push wires), cables, fibers, and/or flexible shafts. To illustrate, the robotic arms  112  can be configured to actuate multiple pull wires coupled to the scope  120  to deflect the tip of the scope  120 . Pull wires can include any suitable or desirable materials, such as metallic and/or non-metallic materials such as stainless steel, Kevlar, tungsten, carbon fiber, and the like. In some embodiments, the scope  120  is configured to exhibit nonlinear behavior in response to forces applied by the elongate movement members. The nonlinear behavior can be based on stiffness and compressibility of the scope  120 , as well as variability in slack or stiffness between different elongate movement members. 
     Example Control System 
       FIG.  12    illustrates example details of the control system  140  in accordance with one or more embodiments. As illustrated, the control system  140  can include one or more of the following components, devices, modules, and/or units (referred to herein as “components”), either separately/individually and/or in combination/collectively: control circuitry  1202 , data storage/memory  1204 , one or more communication interfaces  1206 , one or more power supply units  1208 , one or more I/O components  1210 , and/or one or more wheels  1212  (e.g., casters or other types of wheels). In some embodiments, the control system  140  can comprise a housing/enclosure configured and/or dimensioned to house or contain at least part of one or more of the components of the control system  140 . In this example, the control system  140  is illustrated as a cart-based system that is movable with the one or more wheels  1212 . In some cases, after reaching the appropriate position, the one or more wheels  1212  can be immobilized using wheel locks to hold the control system  140  in place. However, the control system  140  can be implemented as a stationary system, integrated into another system/device, and so on. 
     Although certain components of the control system  140  are illustrated in  FIG.  12   , it should be understood that additional components not shown can be included in embodiments in accordance with the present disclosure. Furthermore, certain of the illustrated components can be omitted in some embodiments. Although the control circuitry  1202  is illustrated as a separate component in the diagram of  FIG.  12   , it should be understood that any or all of the remaining components of the control system  140  can be embodied at least in part in the control circuitry  1202 . That is, the control circuitry  1202  can include various devices (active and/or passive), semiconductor materials and/or areas, layers, regions, and/or portions thereof, conductors, leads, vias, connections, and/or the like, wherein one or more of the other components of the control system  140  and/or portion(s) thereof can be formed and/or embodied at least in part in/by such circuitry components/devices. 
     The various components of the control system  140  can be electrically and/or communicatively coupled using certain connectivity circuitry/devices/features, which can or may not be part of the control circuitry  1202 . For example, the connectivity feature(s) can include one or more printed circuit boards configured to facilitate mounting and/or interconnectivity of at least some of the various components/circuitry of the control system  140 . In some embodiments, two or more of the control circuitry  1202 , the data storage/memory  1204 , the communication interface(s)  1206 , the power supply unit(s)  1208 , and/or the input/output (I/O) component(s)  1210 , can be electrically and/or communicatively coupled to each other. 
     As illustrated, the memory  1204  can include a localization component  1214 , a target/trajectory component  1216 , and a user interface component  1218  configured to facilitate various functionality discussed herein. In some embodiments, the localization component  1214 , the target/trajectory component  1216 , and/or the user interface component  1218  can include one or more instructions that are executable by the control circuitry  1202  to perform one or more operations. Although many embodiments are discussed in the context of the components  1214 - 1218  including one or more instructions that are executable by the control circuitry  1202 , any of the components  1214 - 1218  can be implemented at least in part as one or more hardware logic components, such as one or more application specific integrated circuits (ASIC), one or more field-programmable gate arrays (FPGAs), one or more program-specific standard products (ASSPs), one or more complex programmable logic devices (CPLDs), and/or the like. Furthermore, although the components  1214 - 1218  are illustrated as being included within the control system  140 , any of the components  1214 - 1218  can be implemented at least in part within another device/system, such as the robotic system  110 , the table  150 , or another device/system. Similarly, any of the other components of the control system  140  can be implemented at least in part within another device/system. 
     The localization component  1214  can be configured to perform one or more localization techniques to determine and/or track a position and/or an orientation of an object, such as a medical instrument. For example, the localization component  1214  can process input data (e.g., sensor data from a medical instrument, model data regarding anatomy of a patient, position data of a patient, pre-operative data, robotic command and/or kinematics data, etc.) to generate position/orientation data  1220  for one or more medical instruments. The position/orientation data  1220  can indicate a location and/or an orientation of one or more medical instruments relative to a frame of reference. The frame of reference can be a frame of reference relative to anatomy of a patient, a known object (e.g., an EM field generator), a coordinate system/space, and so on. In some implementations, the position/orientation data  1220  can indicate a location and/or an orientation of a distal end of a medical instrument (and/or proximal end, in some cases). 
     In some embodiments, the localization component  1214  can process pre-operative data to determine a position and/or an orientation of an object. The pre-operative data (sometimes referred to as “mapping data”) can be generated by performing computed tomography (CT) scans, such as low dose CT scans. The pre-operative CT images from the scans can be reconstructed into three-dimensional images, which are visualized, e.g. as “slices” of a cutaway view of a patient&#39;s internal anatomy. When analyzed in the aggregate, image-based models for anatomical cavities, spaces, and/or structures of the patient&#39;s anatomy, such as a patient lung network, can be generated. A center-line geometry can be determined and/or approximated from the CT images to develop a three-dimensional volume of the patient&#39;s anatomy, referred to as model data (also referred to as “pre-operative model data” when generated using only pre-operative CT scans). Example uses of center-line geometry are discussed in U.S. patent application Ser. No. 14/523,760, the contents of which are herein incorporated by reference in its entirety. Network topological models can also be derived from CT-images. 
     Further, in some embodiments, the localization component  1214  can perform vision-based techniques to determine a position and/or an orientation of an object. For example, a medical instrument can be equipped with a camera, a range sensor (sometimes referred to as “a depth sensor”), a radar device, etc., to provide sensor data in the form of vision data. The localization component  1214  can process the vision data to facilitate vision-based location tracking of the medical instrument. For example, a pre-operative model data can be used in conjunction with vision data to enable computer vision-based tracking of a medical instrument (e.g., an endoscope). In examples, using pre-operative model data, the control system  140  can generate a library of expected endoscopic images based on the expected path of travel of a scope, with each image being linked to a location within the model. Intra-operatively, this library can be referenced by the control system  140  in order to compare real-time images and/or other vision data captured at a scope (e.g., a camera at a distal end of an endoscope) to those in the image library to assist with localization. 
     Moreover, in some embodiments, other types of vision-based techniques can be performed to determine a position and/or an orientation of an object. For example, the localization component  1214  can use feature tracking to determine motion of an image sensor (e.g., a camera or other sensor), and thus, a medical instrument associated with the image sensor. In some cases, the localization component  1214  can identify circular geometries in pre-operative model data that correspond to anatomical lumens and track the change of those geometries to determine which anatomical lumen was selected, as well as the relative rotational and/or translational motion of the medical instrument. Use of a topological map can also enhance vision-based algorithms or techniques. Furthermore, the localization component  1214  can use optical flow, another computer vision-based technique, to analyze displacement and/or translation of image pixels in a video sequence in vision data to infer camera movement. Examples of optical flow techniques can include motion detection, object segmentation calculations, luminance, motion compensated encoding, stereo disparity measurement, etc. By comparing multiple frames over multiple iterations, the localization component  1214  can determine movement and a location of an image sensor (and thus an endoscope). 
     Furthermore, in some embodiments, the localization component  1214  can use electromagnetic tracking to determine a position and/or an orientation of an object. For example, the localization component  1214  can use real-time EM tracking to determine a real-time location of a medical instrument in a coordinate system/space that can be registered to the patient&#39;s anatomy, which can be represented by a pre-operative model or other model. In EM tracking, an EM sensor (or tracker) including one or more sensor coils can be embedded in one or more locations and/or orientations in a medical instrument (e.g., a scope, a needle, etc.). The EM sensor can measure a variation in an EM field created by one or more static EM field generators positioned at a known location. The location information detected by the EM sensors can be stored as EM data. The localization component  1214  can process the EM data to determine a position and/or orientation of an object, such as a medical instrument. An EM field generator (or transmitter) can be placed close to the patient (e.g., within a predetermined distance) to create a low intensity magnetic field that an EM sensor can detect. The magnetic field can induce small currents in the sensor coils of the EM sensor, which can be analyzed to determine a distance and/or angle between the EM sensor and the EM field generator. These distances and/or orientations can be intra-operatively “registered” to patient anatomy (e.g., a pre-operative model) in order to determine a geometric transformation that aligns a single location in a coordinate system with a position in the pre-operative model of the patient&#39;s anatomy. Once registered, an EM sensor (e.g., an embedded EM tracker) in one or more positions of a medical instrument (e.g., the distal tip of an endoscope, a needle, etc.) can provide real-time indications of a position and/or an orientation the medical instrument through the patient&#39;s anatomy. 
     Additionally or alternatively, in some embodiments, the localization component  1214  can use robotic command and/or kinematics data to determine a position and/or an orientation of an object. Robotic command and/or kinematics data can be indicative of pitch and/or yaw (e.g., of a robotic arm) resulting from an articulation command, such as those used during pre-operative calibration and/or during a procedure. Intra-operatively, calibration measurements can be used in combination with known insertion depth information to estimate a position and/or an orientation of a medical instrument. Alternatively or additionally, these calculations can be analyzed in combination with EM, vision, and/or topological modeling to estimate a position and/or orientation of a medical instrument. 
     Further, in some embodiments, the localization component  1214  can use other types of data to determine a position and/or an orientation of an object. For example, the localization component  1214  can analyze sensor data from a shape sensing fiber (e.g., which can provide shape data regarding a location/shape of a medical instrument), an accelerometer, a gyroscope, a satellite-based positioning sensor (e.g., a global positioning system (GPS)), a radio-frequency transceiver, and so on, embedded on a medical instrument. Such data can be indicative of a position and/or an orientation of the medical instrument. 
     In some embodiments, the localization component  1214  can use input data in combination. For example, the localization component  1214  can use a probabilistic approach where a confidence weight is assigned to a position/orientation determined from multiple forms of input data. To illustrate, if EM data is not as reliable (as may be the case where there is EM interference), the EM data can be associated with a relatively low confidence value and other forms of input data can be relied on, such as vision data, robotic command and kinematics data, and so on. 
     The target/trajectory component  1216  can be configured to determine a position of a target location within the human anatomy and/or a coordinate space/system. A target location can represent a point/point set within the human anatomy and/or a coordinate space/system. For example, the target/trajectory component  1216  can identify one or more points for a target location within a coordinate system, identify coordinates for the one or more points (e.g., X, Y, Z coordinates for each point), and associate the coordinates with the target location. In some embodiments, the target/trajectory component  1216  can use a position and/or orientation of a medical instrument to determine a position of a target location. For example, a scope can be navigated to contact or be within proximity to a target location (e.g., parked in-front of the target location). The localization component  1214  can use localization techniques to determine a position of the scope (e.g., a location of the end of the scope) and/or a position of an object within a field-of-view of the scope. The target/trajectory component  1216  can associate the position of the scope (e.g., the coordinates of the scope) with the target location. Additionally or alternatively, in some embodiments, a scope can deliver a fiduciary to mark a target location and a position of the fiduciary can be determined. 
     A target location can represent a fixed or movable point(s) within the human anatomy and/or a coordinate space/system. For example, if a papilla is initially designated as a target location, coordinates for the target location can be determined and updated as the procedure proceeds and the papilla moves (e.g., due to insertion of a medical instrument). Here, a location of a scope (which can be within proximity to the papilla) can be tracked over time and used to update the coordinates of the target location. In some embodiments, the target/trajectory component  1216  can estimate/predict a position of a target location. Here, the target location can be represented with the predicted position. For example, the target/trajectory component  1216  can use an algorithm to predict coordinates of the target location as the human anatomy moves. The predicted coordinates can be used to determine a target trajectory. 
     The target/trajectory component  1216  can also be configured to determine a target trajectory for a medical instrument or another object. A target trajectory can represent a desired path for accessing a target location. A target trajectory can be determined based on a variety of information, such as a position of a medical instrument(s) (e.g., a needle, a scope, etc.), a target location within the human anatomy, a position and/or orientation of a patient, the anatomy of the patient (e.g., the location of organs within the patient relative to the target location), and so on. For example, a target trajectory can include a line that extends from a position of a medical instrument and/or a location on the skin of a patient to/through a position of a target location within the patient. In examples, a physician can analyze images or models of the human anatomy and provide input to designate a target trajectory, such as by drawing a line on an image of the internal anatomy of a patient. In some embodiments, the target/trajectory component  1216  can calculate a target trajectory initially and/or update the target trajectory throughout the procedure. For example, as a target location moves during the procedure, a target trajectory can be updated due to the change in position of the target location. In examples where a target location is estimated, a target trajectory can represent an estimated path to reach the target location. 
     In some embodiments, a target trajectory and/or a trajectory of a medical instrument can be defined/represented with respect to one or more anatomical planes/axes. For example, a trajectory can be defined/represented as an angle with respect to the coronal/sagittal/transverse plane(s) or another plane/axis (e.g., a 20 degree cranial-caudal angle, 10 degree medial-lateral angle, etc.). To illustrate, the control system  140  can determine a pose of a medical instrument with respect to an EM field generator and/or a location of a target with respect to the EM field generator. The control system  140  can also determine, based on robotic kinematics, a pose of the EM field generator with respect to a robotic system. In some cases, the control system  140  can infer/determine that the robotics system is parallel to the bed. Based on such information, the control system  140  can determine a target trajectory and/or a trajectory of the medical instrument within respect to an anatomical plane, such as an angle with respect to an anatomical plane for the patient on the bed. 
     The user interface component  1218  can be configured to facilitate one or more user interfaces (also referred to as “one or more graphical user interfaces (GUI)”). For example, the user interface component  1218  can generate user interface data  1222  representing an instrument-alignment interface  1224  that includes one or more visualizations to indicate an orientation and/or position of a medical instrument. The user interface component  1228  can use the position/orientation data  1220  regarding a medical instrument, information regarding a target location, and/or information regarding a target trajectory to present, within the instrument-alignment interface  1224 , one or more visualizations indicative of an alignment of an orientation of the medical instrument relative to the target trajectory and/or a proximity of the medical instrument to the target location. Further, the user interface component  1228  can use vision data, such as images captured by a scope, to present information within the instrument-alignment interface  1224 . In examples, information can be overlaid on images from a scope (e.g., augmented image view). The user interface component  1228  can provide the user interface data  1222  or other data to the one or more displays  142  and/or another display(s) for display of the instrument-alignment interface  1224 . 
     The one or more communication interfaces  1206  can be configured to communicate with one or more device/sensors/systems. For example, the one or more communication interfaces  1206  can send/receive data in a wireless and/or wired manner over a network. A network in accordance with embodiments of the present disclosure can include a local area network (LAN), wide area network (WAN) (e.g., the Internet), personal area network (PAN), body area network (BAN), etc. In some embodiments, the one or more communication interfaces  1206  can implement a wireless technology such as Bluetooth, Wi-Fi, near field communication (NFC), or the like. 
     The one or more power supply units  1208  can be configured to manage power for the control system  140  (and/or the robotic system  110 , in some cases). In some embodiments, the one or more power supply units  1208  include one or more batteries, such as a lithium-based battery, a lead-acid battery, an alkaline battery, and/or another type of battery. That is, the one or more power supply units  1208  can comprise one or more devices and/or circuitry configured to provide a source of power and/or provide power management functionality. Moreover, in some embodiments the one or more power supply units  1208  include a mains power connector that is configured to couple to an alternating current (AC) or direct current (DC) mains power source. 
     The one or more I/O components  1210  can include a variety of components to receive input and/or provide output, such as to interface with a user. The one or more I/O components  1210  can be configured to receive touch, speech, gesture, or any other type of input. In examples, the one or more I/O components  1210  can be used to provide input regarding control of a device/system, such as to control the robotic system  110 , navigate the scope or other medical instrument attached to the robotic system  110 , control the table  150 , control the fluoroscopy device  190 , and so on. As shown, the one or more I/O components  1210  can include the one or more displays  142  (sometimes referred to as “the one or more display devices  142 ”) configured to display data. The one or more displays  142  can include one or more liquid-crystal displays (LCD), light-emitting diode (LED) displays, organic LED displays, plasma displays, electronic paper displays, and/or any other type(s) of technology. In some embodiments, the one or more displays  142  include one or more touchscreens configured to receive input and/or display data. Further, the one or more I/O components  1210  can include the one or more I/O devices  146 , which can include a touchscreen, touch pad, controller, mouse, keyboard, wearable device (e.g., optical head-mounted display), virtual or augmented reality device (e.g., head-mounted display), etc. Additionally, the one or more I/O components  1210  can include one or more speakers  1226  configured to output sounds based on audio signals and/or one or more microphones  1228  configured to receive sounds and generate audio signals. In some embodiments, the one or more I/O components  1210  include or are implemented as a console. 
     Although not shown in  FIG.  12   , the control system  140  can include and/or control other components, such as one or more pumps, flow meters, valve controls, and/or fluid access components in order to provide controlled irrigation and/or aspiration capabilities to a medical instrument (e.g., a scope), a device that can be deployed through a medical instrument, and so on. In some embodiments, irrigation and aspiration capabilities can be delivered directly to a medical instrument through separate cable(s). Further, the control system  140  can include a voltage and/or surge protector designed to provide filtered and/or protected electrical power to another device, such as the robotic system  110 , thereby avoiding placement of a power transformer and other auxiliary power components in robotic system  110 , resulting in a smaller, more moveable robotic system  110 . 
     The control system  140  can also include support equipment for sensors deployed throughout the medical system  100 . For example, the control system  140  can include opto-electronics equipment for detecting, receiving, and/or processing data received from optical sensors and/or cameras. Such opto-electronics equipment can be used to generate real-time images for display in any number of devices/systems, including in the control system  140 . Similarly, the control system  140  can include an electronic subsystem for receiving and/or processing signals received from deployed electromagnetic (EM) sensors. In some embodiments, the control system  140  can also be used to house and position an EM field generator for detection by EM sensors in or on a medical instrument. 
     In some embodiments, the control system  140  can be coupled to the robotic system  110 , the table  150 , and/or a medical instrument, such as the scope  120  and/or the needle  170 , through one or more cables or connections (not shown). In some implementations, support functionality from the control system  140  can be provided through a single cable, simplifying and de-cluttering an operating room. In other implementations, specific functionality can be coupled in separate cabling and connections. For example, while power can be provided through a single power cable, the support for controls, optics, fluidics, and/or navigation can be provided through a separate cable. 
     The term “control circuitry” is used herein according to its broad and ordinary meaning, and can refer to any collection of one or more processors, processing circuitry, processing modules/units, chips, dies (e.g., semiconductor dies including come or more active and/or passive devices and/or connectivity circuitry), microprocessors, micro-controllers, digital signal processors, microcomputers, central processing units, graphics processing units, field programmable gate arrays, programmable logic devices, state machines (e.g., hardware state machines), logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on hard coding of the circuitry and/or operational instructions. Control circuitry can further comprise one or more, storage devices, which can be embodied in a single memory device, a plurality of memory devices, and/or embedded circuitry of a device. Such data storage can comprise read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, data storage registers, and/or any device that stores digital information. It should be noted that in embodiments in which control circuitry comprises a hardware state machine (and/or implements a software state machine), analog circuitry, digital circuitry, and/or logic circuitry, data storage device(s)/register(s) storing any associated operational instructions can be embedded within, or external to, the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry. 
     The term “memory” is used herein according to its broad and ordinary meaning and can refer to any suitable or desirable type of computer-readable media. For example, computer-readable media can include one or more volatile data storage devices, non-volatile data storage devices, removable data storage devices, and/or nonremovable data storage devices implemented using any technology, layout, and/or data structure(s)/protocol, including any suitable or desirable computer-readable instructions, data structures, program modules, or other types of data. 
     Computer-readable media that can be implemented in accordance with embodiments of the present disclosure includes, but is not limited to, phase change memory, static random-access memory (SRAM), dynamic random-access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to store information for access by a computing device. As used in certain contexts herein, computer-readable media may not generally include communication media, such as modulated data signals and carrier waves. As such, computer-readable media should generally be understood to refer to non-transitory media. 
     Example Target Planes and Projected Locations 
     Various techniques herein provide/generate information about an orientation/position of a medical instrument and/or a target trajectory/location. In many examples, such techniques are discussed in the context of a scope that rendezvous with another medical device, such as a needle, catheter, etc., to facilitate removal of a kidney stone or another object from a patient. However, the techniques can be implemented in other contexts. For ease of discussion, many examples will refer to a needle; although other medical instruments can be implemented, as noted above. 
     In one illustration, as similarly discussed in examples above, a physician can navigate a scope to a location within a kidney where a kidney stone is located. The scope can be navigated to contact a papilla and/or otherwise be positioned in proximity to the papilla. The physician can then provide input to register the position of the scope as a target location for a needle to enter the kidney percutaneously. The needle can be equipped with an EM sensor or another type of sensor to provide sensor data, which can be used to determine an orientation/position of the needle. The position/orientation of the needle and/or the position of the target (i.e., the papilla) can be mapped to/projected onto a representation, such as a 2D representation/plane, 3D representation, etc. 
     The mapping can be used to estimate/determine an error/difference between the current needle pose and the target location (sometimes referred to as “targeting error” or “trajectory alignment error”). Targeting error can include angular targeting error that represents an angular error with respect to a target trajectory/pose (e.g., a desired/ideal trajectory/pose for a medical instrument) and/or positional targeting error that represents a positional error with respect to a target location. In examples, angular targeting error and/or positional targeting error can be represented/indicated in targeting data. The targeting data can be used to generate/provide information regarding an alignment/progress of the needle relative to the target location. This can assist a user in inserting the needle to reach the target location. For example, targeting data can be used to present any of the user interfaces discussed herein. 
     In some embodiments, one or more of the techniques discussed herein can be implemented for a moving target (sometimes referred to as a “live target”), such as a target location that can experience movement during a procedure. In examples, a target location that is set to and/or based on a position of a scope and/or anatomy of a patient can move due to anatomical motion and/or tissue deformation when a needle is inserted. In some instances, the location of the target (e.g., papilla) can be updated as the needle is inserted, such as in real-time using the tracked scope pose and/or performing other localization techniques. 
       FIGS.  13 - 16    illustrate examples techniques of mapping a needle pose onto a representation and using such mapping to provide interface data in accordance with one or more embodiments. In these examples, images on the left depict anatomy of a patient (including a kidney  1302 / 1402 / 1502 / 1602 ), as well as a target location  1304 / 1404 / 1504 / 1604  and a pose of a needle  1306 / 1406 / 1506 / 1606 . Meanwhile, images on the right depict one or more interface elements  1308 / 1408 / 1508 / 1608  that can be provided via an interface to indicate the pose of the needle  1302 / 1402 / 1502 / 1602  relative to the target location  1304 / 1404 / 1504 / 1604 . For example, as shown in  FIGS.  13 - 1  through  13 - 3   , the one or more interface elements  1308  can include an instrument alignment element  1308 (A) representing the needle  1306  and an alignment marking  1308 (B) representing the target location  1304 . In general, when the needle  1306  is aligned with the target location  1304 , the instrument alignment element  1308 (A) can be displayed in an aligned arrangement with the alignment markings  1308 (B)/ 1308 (C) (e.g., centered within the alignment marking  1308 (B)). In  FIGS.  13 - 16   , the target location  1304 / 1404 / 1504 / 1604  can be designated by a scope  1310 / 1410 / 1510 / 1610 , which can be used to remove a kidney stone  1312 / 1412 / 1512 / 1612 . 
       FIGS.  13 - 1  through  13 - 3    illustrate example techniques of mapping the pose of the needle  1306  onto a representation/plane  1320  (sometimes referred to as “the target plane  1320 ”) that remains fixed as the pose of the needle  1306  changes. As shown in  FIG.  13 - 1   , the user can position the needle at an initial location  1322 , such as on an insertion site on the skin of the patient or otherwise fix the distal end of the needle  1306  to a position. A line  1324  can then be determined between a distal end of the needle  1306  (e.g., needle tip) and the target location  1304 . The plane  1320  can be determined such that the line  1324  is normal to the plane  1320  and the plane  1320  includes the target location  1304 . A projected position  1326  can be then determined for the needle  1306  on the plane  1320 . For example, a position of the needle  1306  can be projected onto the plane  1320  based on the current orientation/heading of the needle  1306 . The projected position  1326  can represent an intersection of the needle  1306  with the plane  1320  if the needle  1306  were to be inserted to the plane  1320  with the current orientation/heading. As shown, a target trajectory/pose for the needle  1306  can include the line  1324  and/or a line  1328 . The target trajectory/pose can represent a trajectory/pose that should be followed to successfully reach/align with the target location  1304 . Further, in some instances, a target trajectory can include a heading of the scope  1310 , which may or may not be the same as the line  1324 . 
     The projected position  1326  can be used to present the one or more interface elements  1308 , so that the user can view an alignment of the needle  1306  relative to the target location  1304 . For example, the alignment marking  1308 (B) can represent the target location  1304  on the plane  1320  and the instrument alignment element  1308 (A) can represent the projected position  1326  of the needle  1306  on the plane  1320 . The position of the instrument alignment element  1308 (A) relative to the alignment marking  1308 (B) can indicate an alignment of the needle  1306  to the target location  1304 . For instance, as shown in  FIGS.  13 - 1  through  13 - 3   , as the orientation of the needle  1306  is changed (e.g., the user tilts the needle  1306 ) to align with the target pose  1328 , the instrument alignment element  1308 (A) moves closer to/within the alignment marking  1308 (B).  FIG.  13 - 3    illustrates the needle  1306  aligned with the target pose  1328  (i.e., the projected position  1326  aligned with the target location  1304 ). In some examples, the positioning of the one or more interface elements  1308  represents an angular targeting error; namely, a difference between the orientation of the needle  1306  and the target pose  1328 . 
     In some cases, to facilitate the position of one or more interface elements  1308  within the interfaces of  FIGS.  13 - 1  through  13 - 3   , the plane  1320  can be mapped to the interface. That is, a location on the plane  1320  can be mapped to a location within the interface. For example, a particular location on the plane  1320  can be associated with the outer alignment marking  1308 (C), such that the instrument alignment element  1308 (A) can be positioned near the alignment marking  1308 (C) if the projected position  1326  is positioned within proximity to the particular location on the plane  1320 . 
     As noted above, the orientation of the plane  1320  can remain fixed as the pose of the needle  1306  changes. For example, during the needle-insertion phase of the procedure (e.g., while inserting the needle  1306  in an attempt to reach the target location  1304 ), the orientation of the plane  1320  can remain the same, even if the orientation/position of the needle  1306  changes. As such, the plane  1320  generally represents a fixed plane that is formulated based on an initial fixed position of the needle  1306 . In some cases, the plane  1320  can be determined when the distal end of the needle  1306  is initially positioned at a relatively fixed position, such as on the skin of the patient. The fixed position can be detected based on user input indicating that the position is fixed (e.g., switching to a needle alignment interface, selecting a particular icon, etc.), less than a threshold amount of orientation movement of the needle  1320  with the needle tip at a relatively stationary position, and so on. However, in instances, the plane  1320  can be updated based on detecting a new fixed position of the needle  1306  (e.g., orientation movement about a fixed tip point), input provided by a user indicating a new fixed needle position, and so on. 
       FIGS.  14 - 1  through  14 - 3    illustrate example techniques of mapping the pose of the needle  1406  onto a representation/plane  1420  that updates as the pose of the needle  1406  changes in accordance with one or more embodiments. In this example, the user changes the orientation of the needle  1406  without changing the position of the tip of the needle  1406 . As shown in  FIG.  14 - 1   , the user can position the needle at an initial location  1422 . The plane  1420  can be determined such that a heading  1424  of the needle  1406  is normal to the plane  1420  and the plane  1420  includes the target location  1404 . A projected position  1426  can be then determined for the needle  1406  on the plane  1420  based on the current orientation/heading of the needle  1406 . 
     A target trajectory/pose for the needle  1406  can be determined in a variety of manners. In one illustration, a target trajectory/pose can be/include a line  1428  between a distal end of the needle  1406  and the target location  1404 . When the line  1428  is used as a reference, the one or more interface elements  1408  can represent an angular error for the needle  1406  (e.g., an angular difference between the pose of the needle  1406  and the line  1428 ). In another illustration, a target trajectory/pose can be/include a line  1430  that is parallel to the initial heading of the needle  1406  and passes through the target location  1404  (e.g., the line  1430  can be normal to the plane  1420 ). When the line  1430  is used as a reference, the one or more interface elements  1408  can represent a positional error for the needle  1406  (e.g., a positional difference on the plane  1420  between the projected position  1426  of the needle  1406  and the target location). In examples, a target trajectory/pose includes/aligns with a heading of the scope  1410 . In any event, a target trajectory can update as the pose of the needle  1406  changes. 
     The projected position  1426  can be used to present the one or more interface elements  1408 , so that the user can view an alignment of the needle  1406  relative to the target location  1404 . For example, the alignment marking  1408 (B) can represent the target location  1404  and the instrument alignment element  1408 (A) can represent the projected position  1426  of the needle  1406 . The position of the instrument alignment element  1408 (A) relative to the alignment marking  1408 (B) can indicate an alignment of the needle  1406  to the target location  1404 . In this example, the user leaves the tip of the needle  1406  fixed at the initial location  1422  and changes the orientation of the needle  1406 . As shown in  FIGS.  14 - 1  through  14 - 3   , as the orientation of the needle  1406  changes to align with the target trajectory  1428 / 1430  (which changes as the needle  1406  moves), the instrument alignment element  1408 (A) moves closer to/within the alignment marking  1408 (B).  FIG.  14 - 3    illustrates the needle  1406  aligned with the target pose  1428 / 1430  (i.e., the projected position  1426  is aligned with the target location  1404 ). As such, although the interface generally provides both angular and positional error of the needle  1406  relative to the target trajectory, the user is using the interface to view angular error, since the user is changing the orientation of the needle  1406  without changing the tip position. 
     As similarly discussed above in reference to  FIGS.  13 - 1  through  13 - 3   , the plane  1420  can be mapped to the interface to display the one or more interface elements  1408  at the appropriate position within the interface and/or relative to each other. 
       FIGS.  15 - 1  through  15 - 3    illustrate another example of mapping the pose of the needle  1506  onto a representation/plane  1520  that updates as the pose of the needle  1506  changes. In this example, the user changes the position of the tip of the needle  1506  without changing the orientation of the needle  1506 . As shown in  FIG.  15 - 1   , the plane  1520  can be determined in a similar manner as that discussed in reference to  FIGS.  14 - 1  through  14 - 3   . In particular, the user can position the needle at an initial location  1522 . The plane  1520  can then be determined such that a heading  1524  of the needle  1506  is normal to the plane  1520  and the plane  1520  includes the target location  1504 . A projected position  1526  can be determined for the needle  1506  on the plane  1520  based on the current orientation/heading of the needle  1506 . 
     As similarly discussed above in  FIGS.  14 - 1  through  14 - 3   , a target trajectory/pose for the needle  1506  can be determined to be/include (i) a line  1528  between a distal end of the needle  1506  and the target location  1504 , and/or (ii) a line  1530  that is parallel to the initial pose of the needle  1506  and passes through the target location  1504 . The target trajectory can update as the pose of the needle  1506  changes. 
     The projected position  1526  can be used to present the one or more interface elements  1508 . For example, the position of the instrument alignment element  1508 (A) relative to the alignment marking  1508 (B) can indicate an alignment of the needle  1506  to the target location  1504 . In this example, the user changes the position of the tip of the needle  1506  without changing the orientation of the needle  1506 . As shown in  FIGS.  15 - 1  through  15 - 3   , as the position of the needle  1506  changes to align with the target trajectory  1530 , the instrument alignment element  1508 (A) moves within the alignment marking  1508 (B). As such, although the interface generally provides both angular and positional error of the needle  1506  relative to the target trajectory  1528 / 1530 , the user is using the interface to view positional error of the needle  1506  relative to the target trajectory  1530 , since the user is changing the position without changing the orientation. Here, the user may use the needle  1506  to scan for the target location  1504 . 
     As similarly discussed above in reference to  FIGS.  14 - 1  through  14 - 3   , the plane  1520  can be mapped to the interface to display the one or more interface elements  1508  at the appropriate position within the interface and/or relative to each other. 
       FIGS.  16 - 1  through  16 - 3    illustrate another example of mapping the pose of the needle  1606  onto a representation/plane  1620  that updates as the pose of the needle  1606  changes. In this example, the user changes the position of the tip of the needle  1606  and changes the orientation of the needle  1606 . As shown in  FIG.  16 - 1   , the plane  1620  can be determined in a similar manner as that discussed in reference to  FIGS.  14 - 1  through  14 - 3   . In particular, the user can position the needle at an initial location  1622 . The plane  1620  can then be determined such that a heading  1624  of the needle  1606  is normal to the plane  1620  and the plane  1620  includes the target location  1604 . A projected position  1626  can be determined for the needle  1606  on the plane  1620  based on the current orientation/heading of the needle  1606 . 
     As similarly discussed above in  FIGS.  14 - 1  through  14 - 3   , a target trajectory/pose for the needle  1606  can be determined to be/include (i) a line  1628  between a distal end of the needle  1606  and the target location  1604 , and/or (ii) a line  1630  that is parallel to the pose of the needle  1606  and passes through the target location  1604 . The target trajectory can update as the pose of the needle  1606  changes. 
     The projected position  1626  can be used to present the one or more interface elements  1608 . For example, the position of the instrument alignment element  1608 (A) relative to the alignment marking  1608 (B) can indicate an alignment of the needle  1606  to the target location  1604 . In this example, the user changes the position of the tip of the needle  1406  and changes the orientation of the needle  1606 . As shown in  FIGS.  16 - 1  through  16 - 3   , as the position of the needle  1606  changes to align with the target trajectory  1628 / 1630 , the instrument alignment element  1608 (A) moves within the alignment marking  1608 (B). As such, the user is generally using the interface to view both positional error and angular error of the needle  1406 , since the user is changing the position and the orientation. 
     As similarly discussed above in reference to  FIGS.  14 - 1  through  14 - 3   , the plane  1620  can be mapped to the interface to display the one or more interface elements  1608  at the appropriate position within the interface and/or relative to each other. 
     Although various examples are discussed in the context of projecting a position of a needle onto a plane using the tip of the needle as a reference point, in some examples another portion of the needle can be projected onto a plane, such as a proximal end/tip of the needle, a middle portion of the needle, and so on. For example, in returning to the example of  FIGS.  13 - 1   , a proximal end of the needle  1306  can be projected onto the plane  1320  (instead of the tip of the needle  1306 ), such that the projected line includes the proximal end of the needle  1306  and is parallel to the target trajectory  1324 . Here, the projected location of the proximal end of the needle  1306  on the plane  1320  would be above the target location  1304  (and the interface element  1308 (A) would be located in the interface in the upper left corner in  FIG.  13 - 1   ). In some embodiments, a projected position of a needle or another medical instrument on a plane can be determined using one or more projective geometry techniques. Further, although various 2D representations/planes are depicted, other types of representations can be implemented, such as 3D representations. 
     As discussed herein, various techniques can be used to determine a target plane. For example, a target plane can be based on a heading of a scope, such that the heading of the scope is normal to the plane. In some cases, the heading of the scope can also represent a target trajectory. As such, in some instances, this can assist a user in aligning a needle or other medical instrument to access a target site coaxially with a scope heading. 
     Example Coordinate Frames 
     As noted above, a medical instrument can be implemented to reach a target location. In some solutions of using a needle, a particular type of movement of the medical instrument may not be well defined, which may be due to the characteristics of the medical instrument (e.g., a cylindrical form of the needle), a type of sensor being used, and/or characteristics of a system tracking the pose of the medical instrument. As such, it may be difficult to correlate movement of the needle to movement of interface elements within an interface in an effective/intuitive manner. For instance, such solutions can cause a needle indicator to move up within an interface when a needle is tilted to the right relative to a user. This can disorient the user when viewing the interface to manipulate the needle. 
       FIG.  17    illustrates example techniques for establishing one or more coordinate frames to correlate movement of a medical instrument to movement of an interface element within an interface. In general, the techniques can use information about a robotic system to determine a coordinate frame for the medical instrument and use the coordinate frame for the medical instrument to provide information about an alignment/progress of the medical instrument. For example, the techniques can assist in achieving instinctive hand eye coordination by mapping medical instrument movement to a user interface in a manner that correlates to how the medical instrument is being held by a user (e.g., moving an interface icon for a needle left/right within an interface when tilting the needle left/right relative to the user, moving the interface icon up/down within the interface when tilting the needle up/down relative to the user, etc.). This can assist a user in aligning the medical instrument. 
     To illustrate, as noted above, a physician can implement the robotic system  110  to perform a medical procedure. The robotic system  110  can be coupled to the EM field generator  180 , such as to the robotic arm  112 (A). The EM field generator  180  can provide an EM field that is detected by an EM sensor on a medical instrument, such as a needle (not illustrated in  FIG.  17   ). Based on the sensor data from the medical instrument, a pose of the medical instrument can be determined relative to a coordinate frame  1702  of the EM field generator  180 . Further, a coordinate frame  1704  (also referred to as “the world coordinate frame  1704 ”) can be determined for the robotic system  110 , such as fixed to the carriage interface  1104 /base of the robotic arm  112 (A) or any other component of the robotic system  110 . The pose of the medical instrument can then be represented within the world coordinate frame  1704 . In examples, the pose of the medical instrument can be represented in the world coordinate frame  1704  based on a transformation (e.g., a homogeneous transformation) between the coordinate frame  1702  and the world frame  1704  using forward kinematics for the robotic system  110  (e.g., the robotic arm  112 (A)). 
     Moreover, a target location  1706  within a patient (not illustrated) can be determined relative to the coordinate frame  1702  of the EM field generator  180  using any of the techniques discussed herein. A plane  1708  (also referred to as “the target plane  1708 ”) can then be determined based on the target location  1706 . The plane  1708  can then be represented within the world coordinate frame  1704 , such as in a similar manner as the pose of the medical instrument is represented in the world coordinate frame  1704 . Coordinate axes  1710  can then be determined for the target plane  1708 . For example, an assumption/inference can be made that the medical instrument will not be parallel to the z-axis of the world coordinate frame  1704 , which can be used to define a coordinate axis on the target plane  1708  (e.g., a y-axis). A cross product can be performed between the z-axis of the world coordinate frame  1704  and a heading (z-axis) of the medical instrument to define another coordinate axis on the target plane  1708  (e.g., a y-axis). Once two axes are defined, a third axis can be defined by performing a cross product between the newly obtained/determined axis and the heading of the medical instrument.  FIG.  17    illustrates a 3D representation of the plane  1708  (the middle image) and a 2D representation of the plane  1708  (the bottom image). As shown, a projected location  1712  of the medical instrument is shown on the plane  1708  as the origin of the coordinate axes  1710 . Further, the target location  1706  is represented with a bubble on the target plane  1706 . 
     Once the coordinate frame  1710  is determined for the target plane  1708 , a coordinate frame for the medical instrument can be determined. For example, the coordinate frame for the medical instrument can directly translate from the target plane  1708 , since a heading of the medical instrument and the target plane normal can be mirror images of each other. As such, the coordinate frame for the medical instrument can be an inverse of the coordinate frame for the target plane  1708 . 
     In examples, one or more of the following mathematical steps can be performed to generate one or more of the coordinate frames, axes, and/or other elements:
 
world Z =[0,0,1]
 
world X     TP   =world R     needle   [0:2,2]
 
world Y     TP   =world Z ×world X     TP    
 
world Z     TP   =world X     TP   ×world Y     TP    
 
 world   R   TP =[ world   X   TP ,  world   Y   TP ,  world   Z   TP ]
 
 world t TP = world P target  
 
[ BE   P   bubble , 1]=( world   T   TP ) −1 [ world   P   bubble , 1]
 
If  world   R   needle [0:2,2]= world   Z→   world   Z+=eps  
 
Example Adaptive Targeting
 
       FIGS.  18  and  19    illustrate various example adaptive targeting techniques (also referred to as “adaptive scaling”) in accordance with one or more embodiments. In some embodiments, when a medical instrument is relatively far away from a target location (e.g., outside a threshold), some amount of targeting error can be tolerated. However, as the medical instrument moves closer to the target location, a targeting error may need to be smaller (e.g., a size of an anatomical target (such as a size of a papilla), smaller than a size of the anatomical target, or another size) to facilitate access to the target location. As such, in examples, the adaptive targeting techniques can be implemented such that one or more interface features within an interface can function in different manners as a medical instrument moves closer to (or farther away from) a target location (e.g., as the medical instrument is inserted). For instance, when a medical instrument tip is positioned relatively close to a target location, relatively slight deviations from a target trajectory may result in relatively greater movement of an instrument position feature from a target center in the interface, in comparison to when the medical instrument is farther away from the target location. This can assist a physician in aligning the medical instrument with the target location with a greater amount of tolerance when the medical instrument is farther from the target location, and/or assist the physician in more precisely aligning the medical instrument with the target location as the medical instrument approaches the target location. 
       FIG.  18 - 1    shows a user holding or otherwise maintaining a needle  1820  in a certain pose  1821 , wherein the needle  1820  is oriented at a certain axial orientation associated with the pose  1821 . Image  1824  of  FIG.  18 - 1 A  relates to a medical procedure in which a user inserts the needle  1820  in an attempt to advance the tip of the needle  1820  through a renal pyramid  1825  to a target location  1826  (e.g., a calyx puncture location). For example, as described in detail herein, control circuitry of the relevant system may be configured to determine a target needle trajectory  1822  based on the current position  1828  of the needle tip and/or orientation of the needle  1820 . In examples, the target trajectory  1822  may be associated with a direct (or indirect/tortuous) path between the needle tip position  1828  and the target location  1826 , as shown. Therefore, ideal implementation of the relevant medical procedure may involve the user inserting the needle  1820  to the target location  1826  in a manner as to deviate as little as possible from the target needle trajectory  1822 . 
       FIG.  18 - 1 B  shows certain user interface features that may be implemented in connection with a medical procedure as described herein. For example, control circuitry of the relevant system may be configured to generate interface data representing certain visual features as shown and described herein, wherein certain characteristics of such feature(s) are determined and/or based at least in part on detected needle position(s), determined needle target needle trajectory(s), determined target location(s), and/or other information derived using one or more position sensors or other position determination means/mechanism(s). 
     The user interface features shown in  FIG.  18 - 1 B  can include an alignment visualization element  1830  including certain features that may be dynamically adjusted with respect to one or more characteristics thereof in response to changes in needle position, trajectory, and/or the like. In the illustrated example of  FIG.  18 - 1 B , the alignment visualization element  1830  includes an instrument position feature  1832  (also referred to as “the instrument-alignment element  1832 ”), which may have a bubble-type shape or form, or any other shape or form. For example, the instrument position feature  1832  may be configured to visually evoke imagery similar to a bubble level or other leveling instrumentation. The alignment visualization element  1830  may further include an alignment target feature  1831  (also referred to as “the alignment marking  1831 ”), which may be represented as a shape or form defining a boundary around a central target position  1836 , which may generally be associated with an axial center of the alignment visualization element  1830  and/or one or more features thereof. Although illustrated as a full circular boundary, the alignment target feature  1831  may be a broken circle or any other shape or form visually indicating a radial boundary around the target center  1836 . 
     In some embodiments, the alignment visualization element  1830  further includes one or more crosshair features  1833 , which may serve to indicate to the user and/or direct the user visually to the target center  1836 . In examples, the crosshair features  1833  intersect at the target center  1836 . In some embodiments, the alignment visualization element  1830  further includes an outer boundary feature  1834  (also referred to as “the boundary marking  1834 ”), wherein the outer boundary or may provide a visual and/or enforced boundary for the instrument position feature  1832 . The control circuitry may be configured to limit radial distance of the instrument position feature  1832  from the target center  1836  to the outer or inner bounds of the outer boundary feature  1834 . However, in some implementations, the instrument position feature  1832  may be permitted to stray outside the outer boundary  1834 , wherein the outer boundary provides a visual indication to the user relating to the degree to which the instrument position feature  1832  has departed from the target center  1836  and/or alignment target boundary  1831 . 
     According to some implementations of the present disclosure, the instrument position feature  1832  may be presented a distance d t  from the target center  1836  that is based on and/or representative of a distance D P  between a determined needle projection point  1829  lying in a plane  1827  that intersects the target location  1826 . For example, the plane  1827  may be a target entry plane that is substantially orthogonal to the heading/pose of the needle  1820 . However, it should be understood, that the distance D P  between the projected position  1829  and the target location  1826  may be with respect to any plane intersecting the target location  1826 . The projected needle position  1829  may represent a location/position projected for the tip of the needle  1820  if the needle  1820  is inserted along the current trajectory  1823  until it intersects target plane  1827 . However, it should be understood that aspects of the present disclosure relating to projected deviation distances from a target location may represent any projected distance of a needle or other instrument from a target location. With reference to  FIG.  18 - 1 B , the distance d t  between the instrument position feature  1832  and the target center  1836  may be based at least in part on the projected deviation distance D P . 
     In connection with some embodiments disclosed herein, such as with reference to  FIG.  18 - 1 B  and/or other figures of the present disclosure, reference is made to the distance d t  between an instrument position feature  1832  and a target center with respect to an alignment visualization element of a user interface. It should be understood that the distance d t  may be interpreted/represented as a relative dimension relative to the size of one or more other visual features of the alignment visualization element  1830 . That is, where changes in the distance d t  between an instrument position feature and a target center  1836  are described herein, it should be understood that such referenced distances may refer to changes in actual distance as represented on a user interface display, and/or may refer to changes in a distance between the instrument position feature  1832  and the target center  1836  relative to dimension(s) of one or more other visual features of the alignment visualization element  1830 . For example, a change in distance d t  between the instrument position feature  1832  and the target center  1836  may be visually represented by changing the actual distance d t  between the instrument position feature  1832  and the target center  1836  and/or by changing dimensions associated with one or more of the features of the alignment visualization element  1830 , such as the diameter/dimension d 1  of the alignment target feature  1831 , the diameter/dimension d 2  of the instrument position feature  1832 , the diameter/dimension d 3  of the outer boundary feature  1834 , and/or the length and/or position of the crosshair feature(s)  1833 . Therefore, a description herein of change/alteration of the distance between an instrument position feature and a target center of an alignment visualization user interface element can be understood to include changing the distance d t  between the instrument position feature  1832  and the target center  1836 , and/or shrinking or enlarging any of the other dimensions shown in  FIG.  18 - 1 B , such as in a proportional manner. 
       FIG.  18 - 2 A  shows the user holding the needle  1820  at an altered position/pose  1821   b.  For example, image  1837  of  FIG.  18 - 2 A  may represent the needle  1821  in a pose  1821   b  that is associated with further insertion of the needle  1820  toward the target location  1826 . That is, in  FIG.  18 - 2 A , the distance D I-2  between the needle point position  1828   b  and the target location  1826  may be shorter than the distance D I  shown in  FIG.  18 - 1 A .  FIG.  18 - 2 B  shows a modified version of the alignment visualization element  1830 , wherein the distance d tb  of the instrument position feature  1832  has been modified to represent the current position/pose  1821   b  of the needle  1820 . 
     As shown in  FIG.  18 - 2 A , control circuitry can determine a target needle trajectory  1822   b  and/or a current insertion distance D I-2  between the needle tip position  1828   b  and the target location  1826 . The control circuitry may be configured to determine a target deviation distance D P-2 , that represents a current projected deviation between the projected needle position  1829   b  and the target location  1826 . 
     With respect to the image of  FIG.  18 - 2 B , in some examples the alignment visualization element  1830  may be configured to present the instrument position feature  1832  at a distance d tb  from the central target position  1836 , wherein such distance d tb  can be based at least in part on the current projected deviation distance D P-2 . In some implementations, the distance d tb  may have a relationship to the distance d t  of  FIG.  18 - 1 B  that is proportional to the difference between the projected deviation distance D P-2  relative to the projected deviation distance D P . That is, the change in distance of the instrument position feature  1832  from the target center  1836  may be generally linear with respect to the change in projected deviation distance between the pose  1821  and the pose  1821   b.    
     In some implementations, the change in distance of the instrument position feature  1832  from the target center  1836  may be generally nonlinear with respect to the change in projected deviation distance between the pose  1821  and the pose  1821   b.  For example, the degree to which changes in projected deviation distance cause changes in distance between the instrument position feature  1832  and the target center  1836  can be based at least in part on the insertion distance D I /D I-2 . That is, when determining the distance d t /d tb , control circuitry may make such determinations based on the distance D I /D I-2 , at least in part. For example, the distance d tb  may be determined based on a product of projected deviation distance D P-2  and the insertion distance D I-2 , among possibly other multiplier(s). In some implementations, such instrument position feature distance d tb  determination may be performed by control circuitry using one or more insertion distance parameters. For example, such parameter(s) may have a greater value (e.g., results in a greater increase/decrease on instrument position feature distance) for relatively shorter insertion distances. That is, the insertion distance parameter(s) may have a generally inverse relationship with insertion distance, such that the parameter(s) has/have a greater effect on the instrument position feature distance d t  determination as the insertion distance decreases. Here, when the user inserts the needle tip to a position that is relatively close to the target location  1826 , relatively slight deviations from the target needle trajectory may result in relatively greater movement of the instrument position feature  1832  from the target center  1836 . It should be understood that the various distances shown in  FIGS.  18 - 1 A and  18 - 2 A  may be direct vector distances or may be vector component dimensions/distances with respect to any suitable or desirable reference plane or axis. 
     In some examples, the instrument position feature  1832  is presented within the alignment visualization element  1830  without being presented outside of such element  1830 . For instances, dimensions represented by the alignment visualization element  1830  can change linearly as a function of distance between the needle  1820  and the target location  1826 , wherein the position of the instrument position feature  1832  can be positioned within the alignment visualization element  1830  even for relatively large alignment error. To illustrate, a position of the instrument position feature  1832  can be the same for different distances when the alignment error is relatively large, since the instrument position feature  1832  is displayed only within the alignment visualization element  1830  (in some instances) and cropped if it would be positioned outside of the alignment visualization element  1830 . As such, in some instances, as the needle  1820  moves closer to the target location  1826 , the physical representation associated with the alignment visualization element  1830  becomes smaller, even though the alignment visualization element  1830  looks the same. In examples, the user interface (e.g., alignment visualization element  1830  and/or other elements) do not change. An error or distance in pixel space can correspond to smaller error as the needle  1820  moves closer to the target location  1826 . To illustrate, a 2 mm error of the needle  1820  to a target trajectory may not be noticeable when the needle  1820  is relatively far from the target location  1826 , but become noticeable as the needle  1820  moves closer to the target location  1826 . 
       FIGS.  19 - 1  through  19 - 3    illustrate example techniques of scaling a target plane based on an insertion distance of a medical instrument. In  FIGS.  19 - 1  and  19 - 2   , images  1902  and  1904  on the left depict anatomy of a patient (including a kidney  1906 ), as well as a target location  1908  and a pose of a needle  1910 . Further, images  1912  and  1914  in the middle depict target representations on a plane  1916  (also referred to as “the target plane  1916 ”) (e.g., that correspond to physical dimensions that scale with distance to a target). The target plane  1916  can be associated with/include a circle with a defined diameter, wherein the circle can be centered on the target location  1908 . The images  1912  and  1914  are generally not presented to a user, but are provided here for ease of discussion. Moreover, images  1918  and  120  on the right depict one or more interface elements  1922  (e.g., that correspond to fixed user interface dimensions) to indicate a current pose of the needle  1910 . The interface element  1922 (A) can represent the needle  1910 , the interface element  1922 (B) can represent the target location  1908 , and the interface element  1922 (C) can represent a boundary.  FIGS.  19 - 1  and  19 - 2    also illustrate a scope  1924  to assist in removing a kidney stone  1926 . 
     As shown in  FIG.  19 - 1   , when the tip of the needle  1910  is farther from the target location  1908 , the target representation on the target plane  1916  can be relatively large. The target representation can represent the one or more interface elements  1922  (e.g., dimensions of the one or more interface elements  1922 ). For ease of discussion, the target representation is illustrated as being associated/projected onto the target plane  1916 ; however, the features of the target representation can be implemented in other manners without associating/projecting the target representation onto the target plane  1916 . 
     As shown in  FIG.  19 - 2   , as the tip of the needle  1910  moves closer to the target location  1908 , the target representation can change in size, as illustrated in the image  1914 . For example, one or more dimensions of the target representation on the target plane  1916  can be reduced, such that a smaller area on the target plane  1916  corresponds to the one or more interface elements  1922 . As such, a scaling ratio of dimensions represented in the target plane  1916  to dimensions represented in the interface can be adjusted. In some embodiments, a center element  1928  of the target representation can change to be the same as or smaller than a size of an anatomical target, such as a size of a papilla. For example, when the tip of the needle  1910  is with a threshold distance to the target location  1908 , the center element  1928  can be updated to be the same size as (or smaller than) the anatomical target. 
       FIG.  19 - 3    illustrates an example graph  1930  of a scale of the target plane  1916  relative to a distance of the needle  1910  to the target location  1908  (e.g., the insertion distance). In particular, the y-axis represents the distance between the tip of the needle  1910  and the target location  1908 , while the x-axis represents the size of the target representation on the target plane  1916  (i.e., the scaling ratio of distances on the target plane  1916  to distances on the interface). As shown, as the needle  1910  moves closer to the target location  1908 , the relationship between a distance on the target plane  1916  and a corresponding distance in the interface (e.g., a scaling ratio) can be updated. Although a linear relationship is illustrated in  FIG.  19 - 3   , another type of relationship can be implemented (e.g., non-linear, step, etc.). 
     In some instances, the scaling techniques discussed in the context of  FIGS.  19 - 1  through  19 - 3    (and elsewhere herein) can implement adaptive targeting to assist a user in accurately inserting the needle  1910  to reach the target location  1908  (which may be relatively small). For example, such scaling techniques can cause relatively slight deviations from a target trajectory to result in smaller movement of an instrument position feature from a target center in an interface when the needle  1910  is farther from a target location, and cause relatively slight deviations from the target trajectory to result in relatively greater movement of the instrument position feature from the target center when the needle  1910  is positioned relatively close to the target location. In examples, dimension(s) of the one or more interface elements  1922  may not change within an interface as the needle  1910  is inserted (e.g., each interface elements  1922  can maintain the same size/shape). However, in other examples, dimension(s) of the one or more interface elements  1922  may change within the interface. 
     In some embodiments, one or more of the techniques discussed herein can reduce complexity of percutaneously accessing a target location, such as by providing an interface that includes elements to indicate an alignment/position of a medical instrument relative to a target trajectory and/or a target location. In examples, the interface can assist a physician or other user in manually manipulating the medical instrument. Such techniques can enhance the ability of the physician or another user in accurately reaching a target location with the medical instrument, in comparison to other techniques, such as fluoroscopy or ultrasound. 
     Example Anatomical Visualization 
       FIG.  20    illustrates an example anatomical visualization  2000  that can be provided via an interface to assist a user in navigating a medical instrument in accordance with one or more embodiments. In this example, the medical instrument is implemented as a needle; however, the medical instrument can be implemented as other instruments. In some instances, the visualization  2000  can assist a user in aligning the needle with the appropriate orientation to access a target location coaxially, such as coaxially aligned with a renal pyramid/papilla, which can avoid damaging surrounding anatomy (e.g., which can occur due to overshoot of the needle) and/or provide more flexibility for an instrument that is inserted into the access path (e.g., a catheter or another instrument). 
     As shown, the visualization  2000  includes a needle representation  2002  of the needle and an anatomical representation  2004  of anatomy of a patient, such as a calyx network and/or other anatomy associated with the patient. The anatomical representation  2004  can be presented as a 2D or 3D representation within an interface, such as any of the interfaces discussed herein. The visualization  2000  also includes a target region representation  2006  representing a target region that the needle should stay within to reach a target location (represented with a target location representation  2008 ). The target region representation  2006  can be presented as a 2D or 3D representation, such as a 2D cone (as shown), a 3D cone, and so on. The target location and target region can be determined based on an orientation/position of a scope and or another element (represented with an element  2010  in the visualization  200 ). In this example, the target region is aligned with a distal end of the scope, which is positioned within the kidney to designate the target location, such that a line  2012  that is normal to the distal end of the scope (e.g., a line representing a heading of the scope) runs through a center of the target region and target location. The line  2012  may represent a target trajectory in some instances, which may or may not be presented in the visualization  2000 . In examples, as the scope moves, the target region representation  2006  and/or the target location representation  2008  can be updated to maintain alignment with the distal end of the scope. The target location representation  2008  can be presented as a 2D or 3D representation, such as a 2D line (as shown), a 3D sphere/surface, and so on. In examples, the target location representation  2008  is associated with an anatomical target (e.g., scaled to/represents a size of a papilla, which can be 4 or 6 mm). Further, the visualization  2000  can includes a line  2014  representing a heading of the needle. 
     Although various elements are discussed in the context of visualizations, in some instances such elements may not be presented, but may merely be determined/generated for use in evaluating a current pose of the needle  2000  relative to the target location  2008 . For example, the target region and/or an anatomical representation/model may be determined and used to evaluate a current pose of the needle without displaying the target region visualization  2006  and/or the anatomical representation  2004 . 
     Example Instrument States and Regions 
       FIG.  21    illustrates example regions  2102  that can be implemented/generated to determine a state (sometimes referred to as “a progress state”) of a medical instrument in accordance with one or more embodiments. As shown, the regions  2102  are discussed in the context of a needle  2104  accessing a kidney  2106  to assist in removal of a kidney stone  2108 . Here, a scope  2110  is implemented to designate a target location  2112  for percutaneous access by the needle  2104 . However, the regions  2102  can be implemented in the context of other situations/medical procedures. In examples, a state of the needle  2104  can indicate a location/progress of the needle  2104  relative to the target location  2112 . For example, a state can include: an in-progress state indicating that the needle  2104  is being inserted and has not yet reached/passed the target location  2112 , an in-progress and aligned state indicating that the needle  2104  is being inserted and is aligned with a target trajectory/pose, a target-unreachable state indicating that the target location  2112  is unreachable given the current orientation of the needle  2104 , a target-reached state indicating that the needle  2104  has reached the target location  2112 , a target-passed state indicating that the needle  2104  has been inserted beyond the target location  2112 , and so on. A state of the needle  2104  can be used for a variety of purposes, such as to provide an indication via an interface and/or perform other processing. 
     In some embodiments, the regions  2102  are determined based on the target location  2112  and/or a position/orientation of the scope  2110 . For example, a first region  2102 (A) can be determined based on a target plane and/or a position/orientation of the scope  2110 . Here, the region  2102 (A) includes a cone shaped region that is aligned with a line  2114  that is normal to a distal end of the scope  2110 . However, the region  2102 (A) can include other forms/shapes. In this example, the needle  2104  is also aligned with the line  2114 . The region  2102 (A) can be associated with a state in which it is possible to reach the target location  2112  (e.g., an in-progress state, an in-progress and aligned state, etc.). For example, when the needle  2104  is positioned within the region  2102 (A) (e.g., relative to the tip of the needle  2104  and/or any other portion), an indication can be provided via an interface indicating that it is possible to align the needle  2104  with the target location  2112 . Moreover, if the needle is aligned with the line  2114  (e.g., a target pose/trajectory), the needle  2104  can be associated with a state indicating that the needle  2104  is aligned with the target location  2112  (e.g., an in-progress and aligned state). In examples, when the needle  2104  is positioned within the region  2102 (A), a progress indicator can indicate the proximity of the needle  2104  relative to the target location  2112  and/or can indicate that the needle  2104  is in progress of being inserted. 
     Further, a second region  2102 (B) can align with and extend from a distal end of the scope  2110 . Here, the region  2102 (B) includes a particular form; namely, a semicircle with a straight line that aligns with a target plane (partially illustrated in  FIG.  21   ). However, the region  2102 (B) can include other forms/shapes. The region  2102 (B) can be associated with a state in which that the target location  2112  is reached. For example, when the tip of the needle  2104  is located within the region  2102 (B), it can be determined that the target location  2112  is reached. In examples, an indication can be displayed via an interface indicating such state. In one illustration, a progress indicator can be displayed that indicates that the needle  2104  has reached the target location  2112 . In examples, the region  2102 (B) can allow for some amount of overshoot of the target location  2112 . Further, in examples, a dimensions and shape of the region  2102 (B) can be determined based on a dimension and/or shape of human anatomy associated with the target location, such as an average size of a papilla (with an amount of tolerance), a size/shape of another organ/anatomical feature, and so on. In examples, the region  2102 (A) and/or  2102 (B) represent a target region (e.g., a region that the needle  2104  should stay within to reach the target location  2112 ). 
     Moreover, as also shown in  FIG.  21   , the third region  2102 (C) can encompass an area outside of the first and second regions  2102 (A),  2102 (B). The region  2102 (C) can be associated with a state in which the target location  2112  is unreachable, the target location  2112  has been passed, or that the needle  2104  is otherwise not located with the target region. For example, when the tip of the needle  2104  is located within the region  2102 (C), it can be determined that the target location  2112  is unreachable given the current pose of the needle  2104 , that the target location  2112  has been passed (e.g., the needle  2104  has substantially overshot the target location  2112 ), or that the needle  2104  is otherwise not located with the target region. In examples, an indication can be displayed via an interface indicating such state. This can indicate that a physician should stop inserting and/or retract the needle  2104 , as the physician may not be able to correct the needle trajectory at this point and/or the physician has overshot the target location  2112  by a particular amount. In one illustration, if the needle  2104  crosses over into the region  2102 (C), an instrument-alignment element can be displayed in a deformed state and/or another indication can be provided. 
     Example Adaptive Progress Indication 
     As discussed in various examples herein, a proximity/progress of a medical instrument to a target location can be indicated in a user interface or otherwise. In some embodiments, such information is indicated in a linear manner, such that an amount of progress indicated for a unit of movement closer/farther from the target location can consistently be represented by a particular amount of progress change. To illustrate, each 10 mm change in a distance between a tip of a medical instrument and a target location can correspond to a 5% progress change that is displayed within an interface (e.g., to indicate a progress of inserting the medical instrument to the target location). Here, such progress change can be implemented for each 10 mm change until the medical instrument reaches the target location. 
     In other embodiments, one or more adaptive progress indication techniques can be performed to adjust an amount of progress that is indicated for a unit of movement. In one illustration, as shown in the graph  2200  of  FIG.  22   , an amount of progress change indicated for a unit of position change can be based on a distance between a medical instrument and a target location. In this illustration, an insertion distance within a range of 150 mm to 75 mm can be associated with a non-linear progress indication. For instance, each 1 mm change in a proximity to the target location within the 150 mm to 75 mm range can cause an increasing amount of progress to be indicated (e.g., a change from 150 mm to 140 mm can be associated with a 1% change in progress, a change from 140 mm to 130 mm can be associated with a 2% change in progress, etc.). Further, in this illustration, progress change can become linear for changes from 75 mm to and/or past the target location. By implementing such adaptive techniques, progress change within an interface can be minimal when the medical instrument is relatively far from the target location, which may allow a physician to reposition or otherwise select an insertion site without seeing much progress change. Moreover, this can cause the physician to slow down the insertion as the medical instrument approaches the target location, thereby achieving a more accurate needle alignment before reaching the target location. 
       FIG.  22    and the above illustration describe one of many example techniques for adaptive progress indication. As such, other linear or non-linear progress indications can be implemented, such as a piecewise linear function, exponential function, and so on. 
     Although various techniques are discussed herein to determine/present progress/alignment information, a variety of other techniques can be used in addition to or alternatively from such techniques. In some embodiments, a scope can be positioned within proximity to a target location, such as parked in front of a papilla of interest. Here, an image captured by the scope can be presented through an interface to provide a visual confirmation that a target location has been reached, such as in the case when anatomical motion is minimal and/or the scope is parked with the appropriate field of view. In examples, the image from the scope can be analyzed to determine a progress state of a medical instrument. Further, in some embodiments, any of the progress information discussed herein can be presented in addition to or alternatively from the image captured by the scope to assist in confirming that the target location has been reached. Such progress information can be particularly useful when there is substantial anatomical motion, the papilla or other anatomy is pressed against a camera of the scope, and so on. In examples, such progress information can augment images obtained by a scope. Furthermore, such progress information can avoid navigating the scope around to search within the kidneys to confirm if a medical instrument has been inserted into the kidneys. Additionally or alternatively, in some embodiments, a current position of a medical instrument, such as a needle, can be overlaid on an image view of a scope. Additionally or alternatively, in some embodiments a medical instrument can be equipped with an impedance-sensing-electrodes and an impedance signal can be used to classify which medium the medical instrument electrodes are in contact with. In examples, if the impedance signal is classified as urine, it can be determined that the target is reached (e.g., the target-reached state can be determined). 
     Example Flow Diagrams 
       FIGS.  23 - 28    illustrate example flow diagrams of processes for performing one or more techniques discussed herein. The various operations/blocks associated with the processes can be performed by control circuitry implemented in any of the devices/systems discussed herein, or a combination thereof, such as the control system  140 , the robotic system  110 , the table  150 , the EM field generator  180 , the scope  120 , and/or the needle  170 . 
       FIG.  23    illustrates an example flow diagram of a process  2300  for generating data indicating a distance between a projected position of a medical instrument on a plane and a target location on the plane in accordance with one or more embodiments. 
     At block  2302 , the process  2300  can include receiving sensor data from one or more medical instruments. For example, according to certain use cases, control circuitry of a device/system, such as a control system, can receive sensor data via a communication interface from one or more medical instruments, such as a scope, a needle, or any other medical instrument. The sensor data can be indicative of and/or used to determine a position and/or an orientation of the one or more medical instruments. 
     At block  2304 , the process  2300  can include determining a target location within human anatomy. For example, control circuitry can determine a target location within a patient, such as an anatomical landmark, a location of a medical instrument, or any other location/target. In some embodiments, the control circuitry can determine the target location based on sensor data from a medical instrument that is disposed at least partially within the patient (e.g., a scope or another medical instrument). 
     At block  2306 , the process  2300  can include determining a position and/or an orientation of one or more medical instruments. For example, control circuitry can determine a position and/or an orientation of one or more medical instruments based on sensor data from the one or more medical instruments. In some embodiments, the control circuitry can use one or more localization techniques to determine the position and/or the orientation. In examples, a position and orientation of a medical instrument can be referred to as a pose of the medical instrument. 
     At  2308 , the process  2300  can include determining a plane that includes the target location. In one example, control circuitry can determine, based on sensor data of a medical instrument, a plane such that a heading of the medical instrument is normal to the plane. In another example, control circuitry can determine, based on sensor data of a medical instrument, a line between a distal end of a medical instrument and the target location and determine a plane such that the line is normal to the plane. In yet another example, control circuitry can determine, based on sensor data from a scope, a plane such that a heading of the scope is normal to the plane. 
     At  2310 , the process  2300  can include updating an orientation of the plane or maintaining the orientation of the plane as an orientation of a medical instrument changes. In one example, control circuitry can update an orientation of a plane as an orientation of a needle changes such that a heading of the needle remains normal to the plane. In another example, control circuitry can maintain a constant/fixed orientation of a plane as an orientation of a needle changes. In yet another example, control circuitry can update an orientation of a plane as an orientation of a scope changes such that a heading of the scope remains normal to the plane. 
     At  2312 , the process  2300  can include determining a projected position of a medical instrument on the plane. For example, control circuitry can determine a projected position of a medical instrument on the plane based on an orientation/position of the medical instrument. In examples, the projected position can be with respect to a tip of the medical instrument; however, the projected position can be with respect to other portions of the medical instrument, such as a back/proximal end of the medical instrument, a middle portion of the medical instrument, or another portion. 
     At block  2314 , the process  2300  can include generating interface data representing one or more interface elements indicating a distance (e.g., projected deviation distance) between the projected position and the target location on the plane. For example, control circuitry can generate user interface data representing an instrument-alignment element representing an orientation of a medical instrument and/or an alignment marking representing the target location. In some embodiments, a positioning of the instrument-alignment element relative to the alignment marking and/or other features in the interface can indicate an alignment of the medical instrument to a target trajectory. 
     At block  2316 , the process  2300  can include causing display of the one or more interface elements based on the interface data. For example, control circuitry can cause display of an interface via a display device, such as by sending user interface data to a display device associated with a control system. Further, a display device can display an interface based on interface data. In some instances, the interface presents a first interface element a distance from a center of a second interface element, wherein the distance is based on a distance between the projected position and the target location on the plane and/or an insertion distance between a tip of the medical instrument and the target location on the plane. 
       FIG.  24    illustrates an example flow diagram of a process  2400  for updating an amount of progress indicated for a unit of movement of a medical instrument in accordance with one or more embodiments. 
     At block  2402 , the process  2400  can include causing a progress indicator to be displayed indicating a proximity of a tip of the medical instrument to a target location and/or another other portion of the medical instrument to the target location. For example, control circuitry can cause display of a progress indicator via a display device, such as by sending interface data to a display device associated with a control system. Further, a display device can display a progress indicator based on interface data. 
     At block  2404 , the process  2400  can include setting a progress change parameter for the progress indicator to a first value. For example, control circuitry can set a progress change parameter to a first value, wherein the progress change parameter is indicative of an amount of progress change of the progress indicator with respect to a unit of movement of the medical instrument (e.g., a unit of change in proximity of the tip of the medical instrument relative to a target location). 
     At block  2406 , the process  2400  can include determining that the tip of the medical instrument has moved closer to the target location. For example, control circuitry can determine (a first time/instance) that the tip of the medical instrument has moved closer to the target location based on sensor data from the medical instrument. In examples, the control circuitry can determine that the medical instrument moved closer to the target location by a first amount. 
     At block  2408 , the process  2400  can include updating the progress indicator. For example, control circuitry can update (a first time/instance) the progress indicator based on the progress change parameter and/or determining that the tip of the medical instrument has moved closer to the target location. 
     At block  2410 , the process  2400  can include setting the progress change parameter to a second value. For example, control circuitry can set a progress change parameter to a second value based on determining that the tip of the medical instrument has moved closer to the target location. The second value can be associated with a greater amount of progress change of the progress indicator for the unit of movement of the medical instrument than the first value. 
     At block  2412 , the process  2400  can include determining that the tip of the medical instrument has moved closer to the target location. For example, control circuitry can determine (a second time/instance) that the tip of the medical instrument has moved closer to the target location based on sensor data from the medical instrument. In examples, the control circuitry can determine that the medical instrument moved closer to the target location by the first amount. 
     At block  2414 , the process  2400  can include updating the progress indicator. For example, control circuitry can update (a second time/instance) the progress indicator based on the progress change parameter and/or determining that the tip of the medical instrument has moved closer to the target location. In examples, the progress indicator can be updated to indicate a different amount of progress change than that indicated in block  2408 . 
       FIG.  25    illustrates an example flow diagram of a process  2500  for updating a position change parameter indicative of an amount of position change of an interface element for a unit of orientation/movement change of a medical instrument in accordance with one or more embodiments. 
     At block  2502 , the process  2500  can include setting a position change parameter to a first value. For example, control circuitry can set a position change parameter to a first value, wherein the position change parameter can be indicative of an amount of position change of one or more interface elements within an interface with respect to a unit of movement/orientation change of the medical instrument. 
     At block  2504 , the process  2500  can include determining that the medical instrument has moved closer to a target location. For example, control circuitry can determine that a tip of the medical instrument (e.g., needle) has moved closer to the target location based on sensor data from the medical instrument. 
     At block  2506 , the process  2500  can include setting the position change parameter to a second value. For example, control circuitry can set the position change parameter to a second value, wherein the second value is associated with a greater amount of position change of the one or more interface elements within the interface for the unit of movement/orientation change of the medical instrument than the first value. In examples, the position change parameter can be set to the second value based on determining that the medical instrument has moved closer to the target location. 
       FIG.  26    an example flow diagram of a process  2600  for updating a scaling ratio of a plane (e.g., target plane) to an interface in accordance with one or more embodiments. 
     At block  2602 , the process  2600  can include identifying a scaling ratio of dimensions represented on a plane to dimensions represented on an interface. For example, control circuitry can determine a scaling ratio of dimensions for a target plane to dimensions for an interface. 
     At block  2604 , the process  2600  can include determining that a medical instrument has moved closer to a target location. For example, control circuitry can determine that a tip of the medical instrument (e.g., needle) has moved closer to the target location based on sensor data from the medical instrument. 
     At block  2606 , the process  2600  can include updating the scaling ratio. For example, control circuitry can update the scaling ratio based on the determining that the medical instrument has moved closer to the target location. The scaling ratio can be reduced or increased. The scaling ratio can be used to move/represent one or more interface elements within an interface. 
       FIG.  27    illustrates an example flow diagram of a process  2700  for determining a coordinate frame for a medical instrument and/or correlating movement of an interface element to movement of the medical instrument in accordance with one or more embodiments. 
     At block  2702 , the process  2500  can include determining a world coordinate frame for a robotic system associated with a robotic arm. For example, a medical system can include a robotic arm coupled to an electromagnetic field generator and include a needle or other medical instrument configured to generate sensor data based on detection of electromagnetic fields from the electromagnetic field generator. Control circuitry can determine a coordinate frame for the robotic system. 
     At block  2704 , the process  2700  can include representing a pose of a medical instrument in the world coordinate frame. For example, control circuitry can determine a pose of a needle based on sensor data from the needle and/or represent the pose of the needle within the world coordinate frame. 
     At block  2706 , the process  2700  can include representing a plane in the world coordinate frame. For example, control circuitry can determine a target plane based on a target location and/or a pose of a needle and/or represent the target plane within the world coordinate frame. 
     At block  2708 , the process  2700  can include determining a target coordinate frame for the plane represented in the world coordinate frame. For example, control circuitry can determine a target coordinate frame for a target plane based on a pose of a needle within the world coordinate frame. 
     At block  2710 , the process  2700  can include determining a coordinate frame for the medical instrument. For example, control circuitry can determine a coordinate frame for a needle based on the target coordinate frame. 
     At block  2712 , the process  2700  can include moving one or more interface elements within an interface in a direction that is correlated to a direction of movement of the medical instrument relative to the coordinate frame for the medical instrument. For example, control circuitry can cause one or more interface elements to move/update within an interface such that the one or more interface elements move in a direction that is correlated to a direction of movement of a needle relative to a coordinate frame for the needle. In examples, this can allow a user to view an interface element as moving left/right within the interface when tilting the needle left/right relative to the user, up/down within the interface when tilting the needle up/down relative to the user, and so on. 
       FIG.  28    illustrates an example flow diagram of a process  2800  for determining a state of a medical instrument based on a region in which the medical instrument is located in accordance with one or more embodiments. 
     At block  2802 , the process  2800  can include generating progress region data indicating multiple regions for an environment of a medical instrument. For example, control circuitry can generate progress region data based on sensor data from a needle and/or sensor data from a scope. The progress region data can indicate multiple regions within an environment, wherein each region can be associated with a state. 
     At block  2804 , the process  2800  can include determining a region, from among the multiple regions, in which the medical instrument is located. For example, control circuitry can determine, based on sensor data from a needle and/or the progress region data, a region in which the needle is located. 
     At block  2806 , the process  2800  can include determining a state of the medical instrument based on the region. For example, control circuitry can determine a state of a needle based on a region in which the needle is located. Such state can indicate if the needle is within a target region (e.g., associated with reaching a target location), if the needle is aligned with a target trajectory/pose, if the needle is outside the target region, if the needle has reached a target location, if the needle has passed the target location, and so on. 
     At block  2808 , the process  2800  can include causing an indication to be displayed of the state. For example, control circuitry can cause display of a progress/alignment indication via a display device, such as by sending user interface data to a display device associated with a control system. Further, a display device can display a progress/alignment indication based on interface data. In examples, the state of the medical instrument and/or an indication of such state provided via an interface can be updated as the medical instrument changes position/orientation, such as by moving into a different region. 
     Additional Embodiments 
     Depending on the embodiment, certain acts, events, or functions of any of the processes or algorithms described herein can be performed in a different sequence, may be added, merged, or left out altogether. Thus, in certain embodiments, not all described acts or events are necessary for the practice of the processes. 
     Conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is intended in its ordinary sense and is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment. The terms “comprising,” “including,” “having,” and the like are synonymous, are used in their ordinary sense, and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is understood with the context as used in general to convey that an item, term, element, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of X, at least one of Y, and at least one of Z to each be present. 
     It should be appreciated that in the above description of embodiments, various features are sometimes grouped together in a single embodiment, Figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim require more features than are expressly recited in that claim. Moreover, any components, features, or steps illustrated and/or described in a particular embodiment herein can be applied to or used with any other embodiment(s). Further, no component, feature, step, or group of components, features, or steps are necessary or indispensable for each embodiment. Thus, it is intended that the scope of the disclosure should not be limited by the particular embodiments described above, but should be determined only by a fair reading of the claims that follow. 
     It should be understood that certain ordinal terms (e.g., “first” or “second”) may be provided for ease of reference and do not necessarily imply physical characteristics or ordering. Therefore, as used herein, an ordinal term (e.g., “first,” “second,” “third,” etc.) used to modify an element, such as a structure, a component, an operation, etc., does not necessarily indicate priority or order of the element with respect to any other element, but rather may generally distinguish the element from another element having a similar or identical name (but for use of the ordinal term). In addition, as used herein, indefinite articles (“a” and “an”) may indicate “one or more” rather than “one.” Further, an operation performed “based on” a condition or event may also be performed based on one or more other conditions or events not explicitly recited. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     The spatially relative terms “outer,” “inner,” “upper,” “lower,” “below,” “above,” “vertical,” “horizontal,” and similar terms, may be used herein for ease of description to describe the relations between one element or component and another element or component as illustrated in the drawings. It 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 drawings. For example, in the case where a device shown in the drawing is turned over, the device positioned “below” or “beneath” another device may be placed “above” another device. Accordingly, the illustrative term “below” may include both the lower and upper positions. The device may also be oriented in the other direction, and thus the spatially relative terms may be interpreted differently depending on the orientations. 
     Unless otherwise expressly stated, comparative and/or quantitative terms, such as “less,” “more,” “greater,” and the like, are intended to encompass the concepts of equality. For example, “less” can mean not only “less” in the strictest mathematical sense, but also, “less than or equal to.”