Patent Publication Number: US-2021187243-A1

Title: Systems and devices for catheter driving instinctiveness

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 14/666,866, filed Mar. 24, 2015, which claims priority to U.S. provisional patent application Ser. No. 61/969,496, titled “User Interface for Catheter Control,” filed Mar. 24, 2014, and U.S. provisional patent application Ser. No. 61/983,191, titled “Magnetic Encoder for the Measurement and Control of Catheter Roll,” filed on Apr. 23, 2014. The foregoing applications are hereby incorporated by reference into the present application in their entirety. 
     This application is related to U.S. patent application Ser. No. 13/452,029, titled “Balloon Visualization for Traversing a Tissue Wall,” filed Apr. 20, 2012, which is herein incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to a robotic surgical system, and more particularly to systems and devices for improving instinctive control of catheter movement in a patient&#39;s anatomy. 
     BACKGROUND 
     Robotic surgical systems and devices are well suited for use in performing minimally invasive medical procedures, as opposed to conventional techniques that may require large incisions to open the patient&#39;s body cavity to provide the surgeon with access to internal organs. Advances in technology have led to significant changes in the field of medical surgery, such that less invasive surgical procedures, in particular minimally invasive surgery (MIS) procedures, are increasingly popular. 
     MIS is generally defined as surgery that is performed by entering the body through the skin, body cavity, or an anatomical opening, using small incisions rather than large, open incisions in the body. With MIS, it is possible to reduce operative trauma to the patient, hospitalization time, pain and scarring, incidence of complications related to surgical trauma, costs, and recovery time. 
     Special medical equipment may be used to perform an MIS procedure. Typically, a surgeon inserts small tubes or ports into a patient and uses endoscopes or laparoscopes having a fiber optic camera, light source, and/or miniaturized surgical instruments. A robotic catheter system attempts to facilitate this process by controlling the catheter tip with better precision and improved instinctive control. The goal of instinctive driving of a catheter or other elongate member is to move the catheter tip as the operator intends when the catheter is manipulated and observed by the operator remotely. For example, the orientation of the model image of the catheter is adjusted to match that of a real image of the catheter, so that a command to move the model catheter to the right results in the actual catheter tip moving to the right in the reference frame of the real image of the catheter. 
     However, current user interface tools and user interface devices still lack features that facilitate instinctive driving. For example, a user may desire to navigate a catheter to the right, but it may be unclear to the user which pullwire should be manipulated, especially if the catheter is experiencing some degree of roll or twist. Further, correcting or accounting for roll or twist poses challenges to instinctive driving. For example, it may not be apparent to the user if roll has occurred or what direction the catheter tip will head in after catheter roll has occurred. 
     In some cases, sensorizing the catheter may facilitate instinctive driving. For example, Fiber Optic Shape Sensing and Localization (FOSSL) or electromagnetic sensing may be used to sense the shape of a flexible body, such as the catheter during an MIS procedure, to permit visualization of the catheter in the patient&#39;s anatomy. The catheter position and orientation may be transmitted to a visual display to allow an operator (e.g., a surgeon) to analyze the images and make decisions to navigate through the patient&#39;s anatomy instinctively. However, this process is not straightforward and generally requires the operator to interpret multiple two-dimensional images acquired in real time (e.g., fluoroscopic images) in three-dimensional space before engaging in catheter manipulation. 
     Accordingly, there is a need for systems and methods to identify and/or correct catheter roll and to simplify user interface commands for more intuitive controls in order to facilitate navigation through a patient&#39;s anatomy. 
     BRIEF SUMMARY 
     In one aspect, a robotic catheter system may include: a flexible catheter having a proximal end, a distal end, and an articulating portion at the distal end; a sensor coupled with the flexible catheter at or near the distal end; a visual display for displaying an image of at least part of the flexible catheter; a processor for generating a virtual indicator displayed on the image of the flexible catheter, where the virtual indicator indicates a direction of articulation and/or an amount of articulation of the articulating portion of the catheter; and a controller coupled with the proximal end of the flexible catheter to receive a user input and articulate the articulating portion of the catheter in response to the user input. 
     In some embodiments, the controller may include a first control configured to receive an additional user input and rotate the virtual indicator about a longitudinal axis of the catheter in response to the additional user input, without rotating the catheter. For example, the first control may be a control column configured to rotate about an axis relative to a base of the controller, where rotation of the virtual indicator corresponds to rotation of the control column. In some embodiments, for example, rotating the control column in a clockwise direction rotates the virtual indicator in a clockwise direction when the elongate member points into the visual display, and rotating the control column in the clockwise direction rotates the virtual indicator in a counterclockwise direction when the elongate member points out of the visual display. Optionally, the system may further include an actuator coupled to the catheter for articulating the articulation portion, and the controller may include a second control coupled to the actuator for articulating the articulation portion. 
     In some embodiments, the virtual indicator corresponds to the controller, and inputting a user input into the controller causes the processor to generate the virtual indicator indicating a direction of movement of the articulation portion of the flexible catheter. In some embodiments, the virtual indicator corresponds to an actuator coupled to the catheter, and engaging the actuator articulates the articulating portion in a direction of the virtual indicator. In some embodiments, the virtual indicator may include a first graphic symbol corresponding to a first actuator coupled to the flexible catheter, a second graphic symbol corresponding to a second actuator coupled to the flexible catheter, and a third graphic symbol corresponding to a third actuator coupled to the flexible catheter. These graphic symbols may be equally spaced along a circumference of the image of the flexible catheter displayed on the visual display. In various embodiments the graphic symbols may be arrows, stacked bars or a combination of both. 
     In some embodiments, the controller may include multiple controls corresponding to the graphic symbols and coupled to the actuators, and engaging a first control articulates the elongate member in a direction of the first graphic symbol, engaging a second control bends the elongate member in a direction of the second graphic symbol, and engaging a third control bends the elongate member in a direction of the third graphic symbol. In some embodiments, engaging the first control and the second control simultaneously articulates the articulating portion of the flexible catheter in a direction between the first and second graphic symbols. In some embodiments, the controls and corresponding graphic symbols are color coded. In some embodiments, each of the graphic symbols is configured to change in size in proportion to an amount of articulation of the flexible catheter in a direction of the graphic symbols. 
     In various alternative embodiments, the virtual indicator may include at least one graphic symbol, such as but not limited to one or more arrows, stacked bars, ring-and-bead symbols, and/or ring-and-arrow symbols. In some embodiments, the controller includes a joystick. In some embodiments, the processor is configured to track the flexible catheter in the image using computer vision techniques. In such embodiments, the processor may be operable to overlay the virtual indicator on the image in response to tracking information. 
     In another aspect, a method for facilitating a robotic catheter procedure may involve generating, via a processor, a virtual indicator on a visual display, and overlaying the virtual indicator onto an image of at least an articulating portion of a flexible catheter used in the robotic catheter procedure on the visual display. The virtual indicator represents a direction of articulation and/or an amount of articulation of the articulating portion of the flexible catheter. In some embodiments, the method may further involve providing a user input device for receiving user inputs to control articulation of the articulating portion of the flexible catheter, where the user input device corresponds to the virtual indicator. Some embodiments may further involve manipulating the virtual indicator in response to a first user input, where the virtual indicator rotates about a longitudinal axis of the flexible catheter. Optionally, the method may also include articulating the flexible catheter in the direction of the virtual indicator, in response to a second user input. 
     In various alternative embodiments, the virtual indicator may include at least one graphic symbol, such as but not limited to an arrow, stacked bars, a ring-and-bead, and/or a ring-and-arrow. In some embodiments, the virtual indicator correlates to an actuator coupled to the flexible catheter. Some embodiments may also include engaging the actuator to articulate the articulating portion of the flexible catheter in the direction of articulation. Some embodiments may also include changing a size of the virtual indicator in response and in proportion to an amount of articulation of the articulating portion of the flexible catheter in the direction of articulation. Optionally, the method may also include tracking the flexible catheter in the image, using computer vision techniques, to generate tracking information, where the tracking information is used to overlay the virtual indicator on the image flexible catheter. The method may also optionally include registering the image of the flexible catheter with a fluoroscopic image of the flexible catheter to generate registration information, where the registration information is used to overlay the virtual indicator on the image. 
     These and other aspects and embodiments of the invention are described in greater detail below, in relation to the attached drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       While the claims are not to be limited to the illustrated examples, an appreciation of various aspects is best gained through a discussion of various examples thereof. Referring now to the drawings, illustrative examples are shown in detail. Although the drawings represent the exemplary illustrations, the drawings are not necessarily to scale and certain features may be exaggerated to better illustrate and explain an innovative aspect of a given example. Further, the exemplary approaches described herein are not intended to be exhaustive or otherwise limiting or restricting to the precise form and configuration shown in the drawings and disclosed in the following detailed description. Exemplary illustrations of the present invention are described in detail by referring to the drawings as follows: 
         FIG. 1A  is a perspective view of a robotically controlled surgical system, according to one embodiment; 
         FIG. 1B  is a magnified perspective view of a user interface having a controller and visual display of the robotically controlled surgical system of  FIG. 1A ; 
         FIG. 2  is a perspective view of an exemplary catheter assembly of the surgical system of  FIG. 1A ; 
         FIGS. 3 and 4  perspective views of components of the catheter assembly of  FIG. 2 ; 
         FIG. 5  a perspective view of a distal end of an exemplary catheter that is controllable by internal control elements, according to one embodiment; 
         FIG. 6A  is a top view of a controller with button controls, according to one embodiment; 
         FIG. 6B  is a perspective view of a catheter with a virtual indicator overlay, according to one embodiment; 
         FIG. 6C  is a top view of a controller with a joystick control, according to an alternative embodiment; 
         FIG. 7A  is a perspective view of an articulating distal portion of a catheter and top views of the controllers of  FIGS. 6A and 6C , illustrating user input corresponding to the articulation of the distal portion, according to one embodiment; 
         FIG. 7B  is a perspective view of an articulating distal portion of a catheter and top views of the controllers of  FIGS. 6A and 6C , illustrating user input corresponding to a different direction of articulation of the distal portion, according to one embodiment; 
         FIG. 8A  is a perspective view of a catheter with a virtual indicator overlay, according to one embodiment: 
         FIG. 8B  is a perspective view of a catheter with a virtual indicator overlay having a stacked bar configuration, according to an alternative embodiment; 
         FIG. 8C  is a perspective view of a catheter with a virtual indicator overlay having arrows with variable magnitude, according to another alternative embodiment; 
         FIG. 9A  is a perspective view of a distal portion of a catheter with a virtual indicator overlay having a ring-and-bead configuration, according to one embodiment: 
         FIG. 9B  is a perspective view of a catheter with a virtual indicator overlay having a ring-and-arrow configuration, according to an alternative embodiment; 
         FIG. 10A  a perspective view of a distal portion of a catheter arranged perpendicular to a plane of the visual display pointing into the visual display, and a side view of a joystick controller, illustrating its motion corresponding to the motion of the distal portion of the catheter, according to one embodiment; 
         FIG. 10B  a perspective view of a distal portion of a catheter arranged perpendicular to a plane of the visual display pointing out of the visual display, and a side view of a joystick controller, illustrating its motion corresponding to the motion of the distal portion of the catheter, according to one embodiment; 
         FIGS. 11A and 11B  are perspective and side views, respectively, of a controller of the user interface of  FIG. 1B , according to one embodiment; 
         FIG. 12  is a perspective view of a controller of the user interface of  FIG. 1B , according to an alternative embodiment; 
         FIG. 13  illustrates a distal portion of a catheter with a virtual dome constraining the motion of the catheter, according to one embodiment; 
         FIGS. 14A and 14B  illustrates the motion of the distal portion of the catheter enclosed by the virtual dome of  FIG. 13 ; 
         FIGS. 15A and 15B  are top views of a controller of the user interface of  FIG. 1B , according to another alternative embodiment; 
         FIG. 16  is a side view of a distal portion of a catheter, illustrating an effect of distal roll on a catheter with 180 degrees twist; 
         FIGS. 17A and 17B  are end-on and perspective views, respectively, of a distal portion of a catheter, illustrating moments of movement on a catheter tip, according to one embodiment; 
         FIGS. 18A and 18B  are end-on views of a distal portion of a catheter, illustrating roll compensation for no roll and 90 degrees roll, respectively, according to one embodiment; 
         FIGS. 19A and 19B  are perspective and end-on views, respectively, of a magnetic encoder that uses a Hall-effect or magneto-resistive sensor to detect changes in polarity, according to one embodiment; 
         FIGS. 20A and 20B  are exploded and assembled/side views, respectively, of a distal portion of a catheter including the magnetic encoder components of  FIGS. 19A and 19B , according to one embodiment; 
         FIGS. 21A and 21B  are end-on views of a magnetic ring of a magnetic encoder, illustrating asymmetrical weight of the ring, according to one embodiment; 
         FIG. 22A  is a perspective view of a distal portion of a catheter with a distal tip camera, according to one embodiment; 
         FIG. 22B  is a front view of two video displays illustrating image representations of the catheter of  FIG. 22A , illustrating what a user would see on the screen when the catheter is equipped with a camera for zero degrees roll; 
         FIG. 23A  is a perspective view of a distal portion of a catheter with a distal tip camera, according to one embodiment; 
         FIG. 23B  is a front view of two video displays illustrating image representations of the catheter of  FIG. 23A , illustrating what a user would see on the screen when the catheter is equipped with a camera for 90 degrees roll; 
         FIGS. 24A and 24B  are perspective diagrammatic representations of a distal end of a catheter, illustrating roll compensation for no camera roll and 90 degrees camera roll, respectively, according to one embodiment; and 
         FIGS. 25A and 25B  are perspective and end-on views of a catheter system, illustrating a simulated usage of a camera and a guide catheter. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, illustrative embodiments are shown in detail. Although the drawings represent the embodiments, the drawings are not necessarily drawn to scale, and certain features may be exaggerated to better illustrate and explain innovative aspects of an embodiment. Further, the embodiments described herein are not intended to be exhaustive or otherwise limit or restrict the invention to the precise form and configuration shown in the drawings and disclosed in the following detailed description. 
     The disclosure describes systems and devices for improving instinctive driving of an elongate member, for example a flexible catheter. As described herein, a user interface may be configured to take advantage of catheter orientation information, such as roll and/or articulation, to provide a more intuitive controller to navigate the tortuosity of the vasculature. That is, the user interface may use information acquired from sensors, such as electro-magnetic sensors embedded into the catheter, and/or fiber optic sensors that may run the length of the catheter (e.g., FOSSL), for virtual representation of the position and orientation of the catheter within the patient&#39;s anatomy. In some embodiments, sensors may be used to determine and control catheter roll or twist to facilitate instinctive manipulation of a catheter as it is navigated through a patient&#39;s anatomy. A user interface may also use information acquired from the imaging system (e.g., such as fluoroscopy) via computer vision techniques. The disclosed user interface and roll control may take advantage of the received information to provide more intuitive commands to facilitate navigation through the patient&#39;s anatomy. 
     Referring now to  FIG. 1A , a robotically controlled surgical system  100  may include a robotic catheter assembly  102  having a robotic or first or outer steerable component, otherwise referred to as a sheath instrument  104  (generally referred to as “sheath” or “sheath instrument”) and/or a second or inner steerable component, otherwise referred to as a robotic catheter or guide or catheter instrument  106  (generally referred to as “catheter” or “catheter instrument”). Catheter assembly  102  is controllable using a robotic instrument driver  108  (generally referred to as “instrument driver”). During use, a patient is positioned on an operating table or surgical bed  110  (generally referred to as “operating table”) to which robotic instrument driver  108  is coupled or mounted via a setup mount  112 . Setup mount  112  may likewise include a rail system (not shown) configured to allow the setup mount  112  to translate along the length of surgical bed  110 , and a motorized rail, (e.g., rail shark fin illustrated as the triangular plate) configured to tilt the instrument driver  108 . As shown in  FIG. 1A , system  100  includes an operator workstation  114 , an electronics rack  116 , a guide wire manipulator  118 , and an associated bedside electronics box  120 , and instrument driver  108 . A surgeon is seated at operator workstation  114  and can monitor the surgical procedure, patient vitals, and control one or more catheter devices. 
     System components may be coupled together via multiple cables or other suitable connectors  118  to provide for data communication, or one or more components may be equipped with wireless communication components to reduce or eliminate cables  118 . Communication between components may also be implemented over a network or over the Internet. In this manner, a surgeon or other operator may control a surgical instrument while being located away from or remotely from radiation sources, thereby decreasing radiation exposure. Because of the option for wireless or networked operation, the surgeon may even be located remotely from the patient in a different room or building. 
     The workstation  114  may include a user interface  124  configured to receive user inputs to operate various components or systems of the surgical system  100 . The user interface  124  may include a controller  126  to enable the operator to control or manipulate the robotic catheter assembly  102 . For instance, the controller  126  may be configured to cause the catheter to perform various tasks and/or movements (e.g., insert, retract, rotate, articulate, etc.). The controller  126  may be operable to allow the operator to navigate the catheter through the patient&#39;s anatomy via articulating the distal tip of the steerable catheter. 
     In some embodiments, the controller  126  may include a planar input (e.g., a joystick) and surrounding dedicated buttons configured to insert, retract, rotate, and articulate the guide wire and/or catheter, as discussed below. Additionally or alternatively, the controller  126  may include a touch screen configured to display icons corresponding to catheter and/or guide wire movements (e.g., insert, retract, roll, articulate, inflate/deflate a balloon or stent, etc.). Thus, the controller  126  may include one or more buttons, joysticks, touch screens, or other user input devices that may be desirable to control the particular component to which the controller is dedicated. 
     The user interface  124  may include a visual display or screen  128  configured to display information or patient-specific data to the operator located at the workstation  114 . In one embodiment, the visual display  128  may be configured to display patient image data (e.g., x-ray images, Mill images, CT images, ultrasound images), physiological statistics (e.g., blood pressure, heart rate, respiratory rate), and/or patient medical records (e.g., medical history, weight, age). The visual display  128  may likewise be configured to display an image of a portion of the patient at one or more magnification levels. Additionally, the visual display  128  may be configured to receive transmissions indicating catheter position and orientation information for display. For example, the visual display  128  may be configured to display information regarding the position and/or articulation of the distal tip of a steerable catheter. Alternatively or additionally, the user interface  124  may include one or more hazard indicators (e.g., graphics, color-coding, light displays) to indicate a condition of the catheter or the system. For example, if the difference between the magnitude of commanded articulation and magnitude of measured articulation of the catheter increases beyond a threshold level, the catheter may be obstructed, for example in the vasculature, and the user may be alerted to the hazard condition of the catheter. Furthermore, the visual display  128  may be configured to display information to provide the functionalities associated with various controls of the controller  126 , as discussed below. The visual display  128  may comprise one video screen, or may comprise multiple video screens working in conjunction with one another. 
       FIG. 1B  illustrates the workstation  114  and user interface  124  in greater detail. The user interface  124  may receive an operator input and be configured to command movement of a flexible catheter or other flexible elongate member. The user interface  114  may include the physical controller  126 , with which the operator interacts, and at least one visual display  128  configured to depict an image of the elongate member, human anatomy, patient vitals, virtual indicators, etc. For example, a fluoroscopic, CT image, MRI image, or other suitable image may be displayed on the visual display  128 , with a virtual overlay indicating catheter orientation, movement, and/or direction. The controller  126  may be configured to manipulate the virtual representation of the catheter on the visual display  128 , which correspondingly manipulates related components of the physical catheter. That is, manipulating the controller  126  directly corresponds to manipulating the actual catheter. The workstation  114  may be located within the procedure room, or may be located remotely (e.g., in a control room, physician&#39;s office). The controller  126  may include dedicated controls configured to actuate movement of the elongate member. For example, the controller  126  may be configured to cause the catheter assembly  102  to perform various tasks and/or movements. According to another example, the controller  126  may be configured to manipulate the virtual catheter representation on the visual display  128  without likewise manipulating the physical catheter, for example in a predictive user interface, as will be discussed in detail below. 
     Referring now to  FIG. 2 , an instrument assembly  200  for driving and/or manipulating an elongate member includes sheath instrument  104  and the associated guide or catheter instrument  106  mounted to mounting plates  202 ,  204  on a top portion of instrument driver  108 . During use, the elongate catheter portion of catheter instrument  106  is inserted within a central lumen of the elongate sheath portion of sheath instrument  104  such that instruments  104 ,  106  are arranged in a coaxial manner. Although instruments  104 ,  106  are arranged coaxially, movement of each instrument  104 ,  106  can be controlled and manipulated independently. For this purpose, motors within instrument driver  108  are controlled such that carriages coupled to mounting plates  204 ,  206  are driven forwards and backwards on bearings. As a result, a catheter coupled to guide catheter instrument  106  and sheath instrument  104  can be controllably manipulated while inserted into the patient, as will be further illustrated. Additional instrument driver motors may be activated to control articulation of the catheter as well as the orientation of the distal tips thereof, including tools mounted at the distal tip. Sheath catheter instrument  106  is configured to move forward and backward for effecting an axial motion of the catheter, for example to insert and retract the catheter from a patient, respectively. 
     Referring to  FIG. 3 , an assembly  300  includes sheath instrument  104  and guide or catheter instrument  106  positioned over their respective mounting plates  206 ,  204 . In some embodiments, a guide catheter instrument member  302  is coaxially interfaced with a sheath catheter member  304  by inserting the guide catheter instrument member  302  into a working lumen of sheath catheter member  304 . Sheath catheter member  304  includes a distal end that is manipulatable via assembly  300 , as will be further discussed in  FIG. 5 . Sheath instrument  104  and guide or catheter instrument  106  are coaxially disposed for mounting onto instrument driver  108 . However, in some embodiments, a sheath instrument  108  may be used without guide or catheter instrument  106 , or guide or catheter instrument  106  may be used without sheath instrument  104  and may be mounted onto instrument driver  108  individually. 
     Referring to  FIG. 4 , when a catheter is prepared for use with an instrument driver, its splayer is mounted onto its appropriate interface plate. In this case, sheath splayer  308  is placed onto sheath interface plate  206  and a guide splayer  306  is placed onto guide interface plate  204 . In the illustrated example, each interface plate  204 ,  206  has respectively four openings  310 ,  312  that are designed to receive corresponding drive shafts  314 ,  316 .  FIG. 4  illustrates an underside perspective view of shafts  314 ,  316  attached to and extending from the pulley assemblies of the splayers  308 ,  306 . 
     Further, as shown in  FIGS. 3-5 , a sheath instrument  104  may include a sheath splayer  308  having drive shafts  314 . Catheter instrument  106  may include a guide splayer  306  having drive shafts  316 . Drive shafts  316  are each coupled to a respective motor within instrument driver  108  (motors not shown). When 4-wire catheter  304  is coupled to instrument driver  108 , each drive shaft  316  thereof is thereby coupled to a respective wire  504 ,  506 ,  508 ,  510 , as shown in  FIG. 5 . As such, a distal end  502  of catheter  304  can be articulated and steered by selectively tightening and loosening wires  504 ,  506 ,  508 ,  510 . Typically, the amount of loosening and tightening is slight, relative to the overall length of catheter  304 . For example, each wire  504 - 510  typically need not be tightened or loosened more than perhaps a few centimeters. 
     Referring to  FIG. 5 , the operator workstation  114  may include a computer monitor to display a three dimensional object, such as an image  512  of a catheter instrument  304 . Catheter instrument  304  may be displayed within or relative to a three-dimensional space, such as a body cavity or organ, for example a chamber of a patient&#39;s heart or a femoral artery of a patient. In one embodiment, an operator uses a computer mouse to move a control point around the display to control the position of catheter instrument  304 . 
     User Interface for Instinctive Catheter Control 
     Referring to  FIGS. 6A-6C , in one embodiment, a controller  400  ( FIG. 6A ) for manipulating/articulating a catheter  412  ( FIG. 6B ) may include a first control  406 , a second control  408 , and a third control  410 . Each control  406 ,  408 ,  410  may include a visual identifier, such as alphabetical letters A, B, and C, colors such as red, green, and blue, and/or the like, for convenience of the operator. Referring to  FIG. 61 , visual display  404  may depict an elongate member, such as a distal portion of a catheter  412  (or “catheter tip”). In this embodiment, the visual display shows the distal portion of the catheter  412 , with three pull wires  422 ,  424 ,  425  and a virtual indicator overlay displaying on the catheter  412 . In this embodiment, the virtual indicator overly includes three virtual indicators  414 ,  416 , and  418  (or “graphic symbols”), which are arrows in the embodiment shown but may be stacked bars or other direction indicators in other embodiments. Each of the virtual indicators  414 ,  416 , and  418  corresponds to one of the controls  406 ,  408 ,  410  and one of the pull wires  422 ,  424 ,  425 . In some embodiments, the image of the catheter  412  may be an image acquired via any suitable medical imaging technique, such as but not limited to fluoroscopy, magnetic resonance imaging (MRI), ultrasonography, computed tomography (CT), or the like. Alternatively, the image of the catheter  412  may be a computer generated image. 
     The virtual indicators  414 ,  416 ,  418  are computer-generated images overlaid onto the image of the catheter  412  to illustrate a commanded movement of the catheter  412 , a measured movement of the catheter  412 , a difference between the two, or some combination thereof. Again, each of the virtual indicators  414 ,  416 ,  418  corresponds to one of the controls  406 ,  408 ,  410  and also one of three pull wires  422 ,  424 , and  426  configured to manipulate and/or steer the catheter  412 . In some embodiments, the virtual indicators  414 ,  416 ,  418  and the controls  406 ,  408 ,  410  may be color coded to match one another. Each control actuation, for example pressing the green button, will result in a tensioning a wire that articulates the catheter in a corresponding direction—e.g., the green arrow direction in this example. In some embodiments, fewer or greater amounts of buttons and/or wires may be used. For example, a catheter may include 0 to 5 wires or 5 to 10 wires, or any subrange between those ranges. In one embodiment, a catheter includes 4 wires. In some embodiments, a controller may include 0 to 5 or 5 to 10 buttons or controls or any subrange between those ranges. In one embodiment, a controller includes 4 buttons or controls. In some embodiments, the button-to-wire ratio remains fixed throughout the procedure (e.g., 1:1 button to wire relationship). 
     As mentioned above, in various embodiments, the visual display  404  and virtual indicators  414 ,  416 ,  418  may show a commanded movement of the catheter  412 , a measured movement of the catheter  412 , a difference between the two, or some combination thereof. “Commanded movement” or “commanded value” is intended to mean the direction (and in some embodiments the amount) of catheter movement directed by a user via the controls  406 ,  408 ,  410 . “Measured movement” or “measured value” is intended to mean the direction (and in some embodiments the amount) of catheter movement measured by the system  100 , for example via a sensor (or multiple sensors) on the catheter. In some embodiments, for example, the visual display  404  may show a user the direction in which the catheter  412  has been commanded to articulate, an amount of commanded articulation in the commanded direction, and also a direction and amount of actual, measured articulation of the catheter. This type of information allows the user to see how the instructed/commanded movements have translated into actual/measured movements. As discussed further below in terms of several alternative embodiments, the visual display  404  may provide this information using any of a number of different types of visual indicators  414 ,  416 ,  418 , such as arrows of different sizes and shapes, stacked bars having sizes and numbers corresponding to amounts of commanded articulation of a catheter, and the like. The overlay of indicators onto an image of a catheter to provide information about catheter movement to a user may be very advantageous in providing an intuitive catheter driving experience for the user. 
     In some embodiments, the visual display  404  of the user interface may be configured to display information near the tip of the depicted catheter  412  so that the information stays within the operator&#39;s field of vision at all times of the procedure, unless turned off explicitly. As such, a virtual representation may overlay an imaged catheter  412  on the visual display  404  (e.g., a viewing screen), which includes virtual indicators  414 ,  416 ,  418  corresponding to visual identifiers disposed on the controls  406 ,  408 , and  410 . The visual display  404  may illustrate which direction the catheter will articulate in response to actuating a control corresponding to the virtual indicator. For example, the green arrow may indicate the catheter will move radially in the depicted direction with respect to an axis in a plane of the visual display  404 . 
     In some embodiments, a processor (not shown) may be configured for generating the virtual representation of the catheter  412  using kinematic, FOSSL, electro-magnetic information, or imaging information acquired by computer vision techniques, for example, regarding the catheter. The processor may be configured to superimpose the virtual indicators  414 ,  416 ,  418  over the tip of the catheter  412 . For instance, virtual indicators  414 ,  416 ,  418  may overlay a fluoroscopic or like image of the catheter  412  inserted in the patient&#39;s anatomy, such that the visual display  404  shows the fluoroscopic image with the virtual indicator overlay to improve instinctive navigation of the catheter. Further, the processor may be configured to adjust the virtual indicators  414 ,  416 ,  418  with corresponding movements of the catheter, such that the indicators  414 ,  416 ,  418  overlay the catheter  412  in proper position/orientation as the catheter  412  moves within the patient&#39;s anatomy. For example, if the catheter  412  rolls or twists during navigation, the virtual indicators  414 ,  416 ,  418  may adjust accordingly, such that the user always knows which wire to manipulate to drive the catheter  412  to the desired location in the vasculature. In some embodiments, a non-transitory medium (not shown), storing a set of instructions may be configured to superimpose the virtual indicators  414 ,  416 ,  418  over a fluoroscopic image of the catheter  412 . The instructions may additionally be operable to allow an operator to manipulate the catheter  412  via input from the controller  400 . In some embodiments, the instructions may be updated periodically to account for changes in catheter orientation and/or position, for example if the catheter  412  rolls or twists during navigation. 
     In some embodiments, as shown in  FIG. 6A , the controller  400  may include a planar input device, such as control buttons  406 ,  408 ,  410 , as described above. The button-to-wire relationship may be fixed throughout the entire procedure, such that a particular button press may always cause a particular wire to be pulled—for example, pressing the green button will always pull the green wire, regardless of catheter orientation on the visual display  404 . Further, in some embodiments, the controller  400  may include three button controls  406 ,  408 , and  410 , corresponding to the three pull wires  422 ,  424 ,  425  in the catheter  412 , for example as represented by the three virtual indicators  414 ,  416 , and  418  as shown in  FIG. 6B . Pressing the control button  408  correspondingly actuates the pull wire  424  associated with virtual indicator  416 . As shown in  FIG. 6A , the controller  400  may optionally include a fourth control  420  configured to release or relax the pull wires  422 ,  424 ,  425  and thereby relax the catheter  412  to a straight position. In one alternative embodiment (not shown), each control button may include two separate buttons, in which the inner button would release the pull wire associated with the controller and hence relax the catheter (e.g., relaxing red button would relax the red wire). The outer button would pull or tension the wire to articulate the catheter in the direction of the virtual indicator. 
     The control buttons  406 ,  408 ,  410 , and/or  420  may be touch sensitive, such that the harder a button is pushed or the more force exerted on the button, the more the button will actuate, pull, or tension the corresponding pull wire  422 ,  424 ,  425 . Thus, a button pushed fully to the base of the controller  400  may pull the corresponding wire to the maximum, so that the catheter  412  is articulated maximally in the direction of the pulled wire  422 ,  424 ,  425 . 
     Further, the control buttons  406 ,  408 ,  410  may be combined or actuated simultaneously to articulate the catheter  412  in a direction that lies in between two pull wires  422 ,  424 ,  425 . For example, still referring to  FIG. 6A , if control buttons  406  and  408  are pushed together, the system would pull wires  422  and  424 , associated with indicators  414  and  416 , thereby making the catheter  412  articulate in a direction between pull wires  422  and  424 . 
     Referring now to  FIG. 6C , in some embodiments, a controller  426  may include a control column or joystick  428  operable to gradually move about the base of the controller  426 . In some embodiments, the controller  426  may include the joystick  428  and visual identifiers  430 ,  432 ,  434  on the controller  426  base, which indicate direction and/or corresponding virtual indicators and pull wires  422 ,  424 ,  425 . For example, the graphics may relate to the virtual indicators  414 ,  416 ,  418  on the visual display  404  as well as the pull wires  422 ,  424 ,  425  running through the catheter  412  to perform movements. Further, as an analog device, the joystick  428  can move gradually between adjacent buttons to mimic either single or simultaneous control button input, and the articulation direction of the catheter would thereby vary smoothly between wires. The joystick  428  may be arranged concentrically with respect to the pie-shaped graphic drawing (e.g., analogous to the three button controller  400 ). The graphics  430 ,  432 , and  434  suggest which pull wire  422 ,  424 ,  425  will be pulled if the joystick  428  is moved in a particular direction. 
     In one embodiment, the joystick  428  may include a return, for example a spring. Alternatively, the joystick  428  may not be loaded with a return, which means the joystick  428  will not return to the center when external force is removed. For example, the joystick  428  may be a position control device that maintains its tilt or orientation when released or external force on the joystick is removed. In some embodiments, the joystick  428  in a straight up, vertical, or perpendicular position relative to the controls may be equivalent to the catheter being fully relaxed, while the full forward position of the joystick (e.g., in relation to  FIG. 6C , fully forward on graphic  430 ) means the wire associated with  430  is pulled or tensioned to the maximum, so that the catheter  412  is articulated maximally in the  430  direction. Stated alternatively, if red is the indicator associated with  430 , pushing or manipulating the joystick  428  fully towards red will pull or tension the red wire  422  maximally, so the catheter  412  is articulated maximally in the red direction, as indicated by a red virtual marker  414  on the visual display  404 . Advantageously, a controller  426  with a joystick  428  enables the operator to easily determine how much effort was required for tensioning each wire  422 ,  424 ,  425 , by observing the orientation or position of the joystick  428 . Further, the joystick  428  indicates the degree of effort the controller  426  attempts to effectuate catheter articulation. For example, if the joystick  428  is only slightly offset from center, then minimal effort may be exerted in pulling or tensioning the wire. Alternatively, if the joystick  428  is fully actuated, then full force may be exerted on the wire and the catheter  412  is maximally articulated, e.g., in the current environment. However, while the controller may exert maximum effort in attempting to articulate the catheter  412 , the catheter  412  itself may not articulate, if there is an obstruction from the human anatomy and/or if the catheter  412  is experiencing roll or twist, for example. 
       FIGS. 7A and 7B  illustrate equivalent button and joystick control inputs that would cause a catheter  612  to articulate toward a red wire  622  ( FIG. 7A ) and in between the red wire  622  and a blue wire  624  ( FIG. 7B ). For example,  FIG. 7A  shows a catheter  612  responding to a single control button push or joystick movement in the direction of red  606  and consequently pulling or tensioning the red wire  622  represented by the red indicator  614 , thereby articulating the catheter  612  in the direction of the large arrow  620 . Alternatively,  FIG. 7B  illustrates the catheter  612  responding to a simultaneous red and blue button  606 ,  610  press or the joystick moving in between the red and blue  606 ,  610  graphics. Simultaneously actuating controls  606  and  610  will trigger corresponding wires  622  and  624  (e.g., represented by virtual indicators  616 ,  618 ) to pull or tension, resulting in articulation of the catheter  612  in the direction of the large arrow  620 . While some embodiments may have a separate color button for each wire on the catheter  612 , an alternative embodiment may involve a bend button and a rotate button with colors of the wires identified on the rotate button. In this embodiment, the user would use the rotate button to orient with the required color and then press the bend button to bend in the required direction. This has the advantage of not requiring a bend button for each wire on the circumference of the catheter. 
     Referring now to  FIGS. 8A-8C , alternative embodiments of a visual display  700 ,  720 ,  730  may be used to illustrate movement of a catheter  702 , for example to enhance instinctive navigation of the catheter  702 . In the embodiment of  FIG. 8A , the visual display  700 , virtual indicators  704 ,  706 ,  708  are superimposed on a fluoroscopic image of the catheter  702 , In order to easily identify which wire is controlled by which control (e.g., buttons or action of the joystick), identifiers for each wire are displayed near or superimposed onto the tip of the catheter. In one embodiment, a red indicator  704 , a green indicator  706 , and a blue indicator  708  are overlaid or superimposed onto three control wires  710 ,  712 , and  714 , respectively. The virtual overlay indicators  704 ,  706 ,  708  likewise match the colors of the controls discussed above, indicating their one-to-one relationship (e.g., the control-to-wire relationship is fixed throughout the procedure, such that a particular control will always cause a particular wire to be pulled). Further, the indicators  704 ,  706 ,  708  are intuitive and easily distinguishable, so that the operator may immediately recognize the indicator  704 ,  706 ,  708  (and consequently the corresponding pull wire) upon glancing at it. 
     In some embodiments, a view of the catheter may change during a procedure or use case. In some embodiments, a catheter orientation or position may be indicated in a first or second view of the catheter using one or more methods, for example shading or coloring of the catheter based on the depth of the catheter into the viewing plane away from the user or 3-D viewing technology that may be manipulated (e.g., rotated, magnified) to view the catheter from one or more directions. In some such embodiments, the virtual indicator may automatically change and update based on the current view. For example, if the controls are labeled “green” for left and “blue” for right in a first view, the virtual indicators may be exchanged such that “green” still means left and “blue” still means right in a second view, for example if the catheter has rolled or twisted in the second view. 
     In some embodiments, the first view may be instinctive while the second view is not instinctive. In some such embodiments, a focus, gaze, or attention of a user may be tracked, for example by a camera, to determine which view the user is using, such that the instinctiveness of the view relies on whether the user is using that particular view. Alternatively, the system may force the user to use, for example, only the first view as their primary view by either changing the size of the view or changing the on-screen indicators, such that first view is the instinctive view. 
     Furthermore, in addition to being color coordinated, the overlay virtual indicators  704 ,  706 , and  708  may be extended or enlarged to demonstrate the load on the wire (e.g., an amount or duration of force placed on the wire), which may serve as an important metric in determining whether the patient&#39;s anatomy is restricting movement. For example, the operator may compare the control effort (e.g., the magnitude of the virtual indicator) with the actual articulation amount of the catheter to determine if a patient&#39;s anatomy is restricting the movement of the catheter. 
       FIG. 8B  illustrates another embodiment, in which a visual display  720 , uses stacked bar indicators  724 ,  726 ,  728 , with variable magnitude representing differing wire loads.  FIG. 8C  illustrates another embodiment of a visual display  730 , in which arrow indicators  734 ,  736 ,  738  have differing magnitudes representing differing wire loads. Either or both of the embodiments illustrated in  FIGS. 8B and 8C  may also be used with the embodiment of the visual display  700  illustrated in  FIG. 8A . A bar or arrow with greater magnitude represents the load on the wire, which is correspondingly greater. Accordingly, the operator may thereby minimize unwanted damage to vessel walls by observing the changing magnitude of the virtual indicator and comparing the actual movement of the catheter. If the magnitude is great and the movement is minimal, the operator may conclude that the catheter is being restricted by the patient&#39;s anatomy. Additionally or alternatively, the user interface may be configured to provide a tactile feedback indicating that the catheter is being restricted by the patient&#39;s anatomy (e.g., the joystick vibrates upon being obstructed). 
     Predictive User Interface for Instinctive Catheter Control 
     In some embodiments, the user interface  124  may be configured to receive an operator input and command the movement of a virtual representation, e.g., a virtual indicator, overlaying an image of a flexible catheter, for example generated by a processor. In some embodiments, the virtual indicator does not represent the current articulation direction of the elongate member, but rather indicates which movement the catheter would make, if the motors/drivers where engaged, e.g., a predictive virtual representation. The predictive virtual indicator may overlay or otherwise be superimposed over an actual image of the catheter (e.g., via medical imaging such as fluoroscopy, thermography, magnetic imaging, ultrasonography, computed tomography, positron emission tomography, etc.). The virtual indicator may be aided in tracking the catheter in the image using computer vision techniques to process the image and determine the catheter location. 
     Referring now to  FIGS. 9A and 9B , two alternative embodiments of virtual indicator overlays  802 ,  822  on images  800 ,  820  of a distal portion of a catheter  808  are illustrated. In the embodiment shown in  FIG. 9A , the virtual indicator overlay  802  is a graphic symbol including a bead  804  on a ring  806 . The position of the bead  804  along the ring  806  indicates a bend direction of the catheter  808 , and the bead  804  may move around the circumference of the ring  806 , as indicated by the double-pointed arrow. In another embodiment, as illustrated in  FIG. 9B , the image  820  may include a virtual indicator overlay  822  that includes a ring  826  and an arrow  824 . The arrow  824  may indicate bend directionality in a way that is similar to that of the bead  804  and may similarly move around the circumference of the ring  826 . In some embodiments, the arrow  824  may also grow and/or shrink in size to indicate the amount of commanded bending signal (e.g., the amount of bend commanded by the user via a user input). As shown in  FIGS. 9A and 9B , the bead  804  or arrow  824  virtual indicator represents the direction the catheter  808  would articulate if the controller were engaged. Stated alternatively, the predictive virtual indicator  802 ,  822  uses available elongate member or catheter roll information to notify the operator of the imminent articulation direction before the elongate member  808  is articulated. 
     Importantly, the predictive virtual indicator overlay  802 ,  822  may instruct the operator whether the catheter  808  is pointing into or out of the screen when the elongate member  808  is positioned in a plane perpendicular to the visual display  128 . It can be very difficult to decipher whether the elongate member  808  is pointing into or out of the visual display  128 . In some embodiments, the direction in which the ring or arrow virtual indicator  822  rolls in relation to direction of the controller input may determine whether the elongate member  808  is pointing into or out of the screen in a plane perpendicular to the visual display  128 . 
     For example, as shown in  FIGS. 10A and 10B , the bead  804  (or arrow  834  in an alternative embodiment) on the predictive indicator  802  may roll in the opposite direction of the controller input if the elongate member  808  is pointed out of the visual display  128  (e.g., the elongate member  808  is facing towards the operator). For example,  FIG. 10A  illustrates the elongate member  808  pointing into the visual display when the predictive virtual indicator  804  rolls in the same direction as that of a joystick  838  (e.g., both roll clockwise). Alternatively,  FIG. 10B  illustrates the elongate member  808  pointing out of the visual display, because the predictive virtual indicator  804  rolls in a direction opposite of the joystick  838  (e.g., controller rolls clockwise and the predictive indicator rolls counterclockwise). Accordingly, the operator can easily decipher the heading of the elongate member  808  without actually articulating the elongate member  808  and thus potentially harming the patient&#39;s vasculature. 
     In some embodiments, the visual display  128  ( FIGS. 1A and 1B ) may be in communication with a processor (not shown). The processor may generate the virtual indicator  802  overlaid on an actual image of a catheter  808  inserted into the patient&#39;s anatomy. The processor may be configured to adjust or manipulate the virtual indicator  802  to indicate which direction the catheter  808  would articulate if the controller were engaged. Further, the processor may be operable to dynamically determine the desired articulation direction of the catheter (e.g., which wire(s) to pull/tension and which wire(s) to relax) based on the bead/arrow position on the virtual indicator  802 . A non-transitory medium (not shown) storing a set of instructions may include one or more instructions to superimpose the virtual indicator  802  on the tip of the catheter  808  and one or more instructions for allowing the operator to rotate the virtual indicator  802  circumferentially around an axis. Additionally, the set of instructions may further include one or more instructions for allowing the user to manipulate multiple controls to move the catheter/elongate member  808 , and may include a set of instructions for using kinematic information or sensor data (e.g., FOSSL, electromagnets), for example, to orient, position, and coordinate the virtual indicator  802  with the catheter  808 . The virtual indicator  802 , therefore, advantageously uses available catheter  808  roll information to notify the operator of the imminent articulation direction before the catheter  808  actually articulates. Accordingly, the operator is encouraged or expected to interact with the virtual indicator  802  and visual display  128  to fine-tune the orientation of the virtual bead or arrow. 
     Once the catheter  808  is actually articulated, the virtual indicator  802  will show the actual movement of the catheter  808 . Thus, the indicator  802  not only shows the user how the catheter  808  will (or should) articulate before actual articulation, but it also shows the user how the catheter  808  actually articulates. 
     Referring now to  FIGS. 11A and 11B , in some embodiments, the controller  844  may include multiple controls, such as a first control  842  configured to roll/rotate the predictive indicator, a second control  846  configured to articulate the elongate member  808 , and a third control  848  configured to relax the elongate member  808 . As shown in  FIGS. 11A and 11B , the first control  842  may include a control column or joystick. Alternatively, in some embodiments, the first control  842  may be a touch sensitive pad. The first control or joystick  842  may be configured to rotate or roll while in the upright or vertical position which correspondingly controls the rotation of the bead or arrow on the ring of the virtual indicator. In some embodiments, the joystick  842  is a position controller and rotating the joystick  842  in the clockwise direction would roll the bead/arrow of the virtual indicator in the same direction (unless, however, if the elongate member is pointing out of the screen, in which case the bead/arrow would roll opposite the direction of the rotation of the joystick  842 ). It should be noted that in some embodiments, the catheter is not actually “rotated” or “rolled” in response to a command to “rotate” or “roll,” but is progressively articulated using pull wires to mimic a rotational movement. For example, if a command is provided to articulate the catheter to the right, the system pulls or tensions a wire to articulate the catheter to the right. Subsequently, if the bead/arrow is rotated 180 degrees and the same articulation button is depressed, the system understands that the bead/arrow has been rotated, and in response pulls or tensions another wire to articulate the catheter to the left. In short, the system may dynamically decide which wire to pull/tension and relax based on the bead/arrow location on the virtual indicator. Further, in this example, the catheter does not physically roll/rotate, but rather the virtual indicator rotates in the visual display. As mentioned, the system  100  is configured to determine the articulation direction (and consequently the respective wire(s) to actuate and relax) in response to the position of the bead/arrow on the virtual indicator. Therefore, the system  100  reduces operator error and minimizes inadvertent touching of vessel walls. 
     The joystick  842  may likewise be configured to tilt forward and backward to command the elongate member to insert or retract, respectively. That is, the joystick  842  is a rocker switch but with added granularity allowing finer motion control. The joystick  842  may be spring loaded so that the joystick  842  returns to its upright/vertical, middle position when no external force is applied. The control input (e.g., tilting for insert/retract and/or the rate of return back to the middle position) may be mapped to the rate of increase or decrease as in velocity control. For example, tilting the joystick  842  fully forwards or backwards may insert/retract the elongate member at a greater velocity than slightly tilting the joystick. The rate at which the joystick  842  returns without external force, however, may be a constant velocity. 
     In some embodiments, the controller  844  may likewise include multiple push controls, for example a second control  846  and a third control  848 . For example, the second control  846  may be configured to articulate the elongate member, while the third control  848  may be configured to relax the elongate member (e.g., an articulation button and a relax button). For example, once the direction is set in which the elongate member would articulate via the joystick  842  (e.g., rotating the bead/arrow), pressing the second control  846  button will physically articulate the elongate member in the set direction. The elongate member may continue to articulate until the force is lifted from the first control  842  (e.g., until the operator releases the articulate button). Further, pressing and holding the third control  848  will gradually relax the elongate member back to its straight configuration. Thus, the elongate member may remain in its articulated configuration until the third control  848  is pressed to relax the elongate member. 
     Referring now to  FIG. 12 , an alternative embodiment of a controller  904  may include a joystick  910 , a bend button  912 , a relax button  914 , a roller  916  and a light feature  918 . The roller  916  (or “fourth control”) may act as a locking feature (or alternatively another form of failsafe mechanism in alternative embodiments), to ensure there is no accidental activation of roll or insertion activities. The roller  916  may be operable to rotate and correspondingly rotate the bead/arrow virtual indicator. Thus, the joystick  910  may be configured to move forward and backward for insertion and retraction, respectively. Alternatively, the joystick  910  may be configured as a toggle button, in which the entire joystick  910  can be pushed down from the top to either activate or deactivate the locking feature. With the roll lock enabled, the roller  916  may still be operable to rotate but without having any effect on the virtual indicator, and hence no change in articulation direction. However, even with the locking feature, the roller  916  may still be used for combining the insertion and roll of the elongate member (e.g., simultaneous actions) by merely disabling/deactivating the lock feature. The controller  904  base may also include the light feature  918  or other indicator, for example a circular area around the base of the controller  904  embedded with different colors to indicate whether the lock has been enabled. 
     Referring now to  FIG. 13  illustrates an image of a dome  920  at a distal end of the elongate member  908 . The dome  920  may represent a constraint for the catheter  908  tip so that at least part of the catheter  908  tip is required to be on a surface of the dome  920  regardless of how the catheter  908  is driven. In one embodiment, the catheter tip motion is confined to a surface of the virtual dome  920  created around a base  922  of its articulation section  924 , and a 3D joystick (not shown), for example, would navigate the catheter tip around the dome&#39;s surface. According to one example, the circumference of the dome  920  may expand depending on the exposed length of the catheter&#39;s articulation section (e.g., a telescoping catheter). Alternatively, the full length of the articulation section may be used to set the size of the dome  920 . 
     A virtual ring  926  may be a projection of the catheter tip onto the dome  920  surface and the bead/arrow  928  indicates which direction the ring would move if the controller were engaged. Accordingly, the virtual indicator  906  is always on the dome  920  surface. Pressing the articulation button as described above would move the catheter  908  tip in the direction towards the bead/arrow  928  along the dome  920  surface. 
     For example,  FIG. 14A  illustrates a response of the catheter  1008  when the virtual indicator  1006  is rolled ninety (90) degrees in clockwise direction prior to the user pressing the articulation button. (The direction of rotation, in this embodiment, is from the perspective of inside of the catheter  1008 . An observer outside the catheter  1008  would view this rotation as appearing counter clockwise.) When the articulation button is pressed, the ring  1026  moves along the surface of the dome  1020  following the direction of the bead  1028 . If the virtual indicator  1006  is rolled forty five (45) degrees more, pressing the articulation button would initially roll and relax the catheter  1008  at the same time, but the catheter  1008  would eventually articulate away from the user, for example as shown in  FIG. 14B . This can be seen in  FIG. 14B , illustrating the successive roll/relax and roll/articulate events. For example, the catheter  1008  relaxes as the tip or ring  1026  straightens and moves towards the top of the dome  1020 , but the articulating angle subsequently increases as the ring  1026  moves further way from the dome  1020  apex. Thus, the relax control button may be redundant as the operator can always roll the indicator  1006  a hundred and eighty (180) degrees and press the articulation button to relax the catheter  1008 . However, the separate control button may make it easier to access this important function, as pressing relax would always bring the catheter  1008  tip back to the top of the dome  1020  following the shortest path regardless of roll and articulation. 
     The virtual dome implementation may use the same physical controller as illustrated in  FIG. 11A, 11B , or  12  (e.g., a 3D joystick with articulate/relax control buttons). Alternatively,  FIG. 15A  illustrates a controller  1100  according to another example. The controller  1100  may have a roll knob  1102 , four control buttons for articulating  1104 , relaxing  1106 , inserting  1108 , and retracting  1110 . The controller  1100  illustrated in  FIG. 15B  is similar in that the roll knob  1102  is the same, but the right and left buttons would be disabled such that the up/down buttons may be used for articulating and relaxing, respectively. A switch or slider  1118  may be operable to move back and forth for inserting and retracting. 
     Roll Compensation for Instinctive Catheter Control 
     Previously, a catheter was presumed to not rotate or roll around its axis as it advances through the vasculature. However, this presumption is not true in reality. For example, as shown in  FIG. 16 , a distal section of a catheter  808  is illustrated with a 180 degree twist. When the controller desires to articulate the catheter to the right, it pulls the wire on the right side of the catheter  808 . However, instead of articulating to the right, the catheter  808  may articulate to the left because of the roll or twist experienced by the catheter  808 . Previously, the controller could not make proper adjustments to correct the action because there was no concept of catheter roll. However, as will be described in further detail below, a roll sensor may be used to enable roll compensation and correction. 
     A roll sensor has the potential to improve the catheter driving experience by enabling the controller to adapt to the inevitable twist or roll in the catheter shaft as it is navigated through the vasculature. For example, the controller may change an amount of wire pull or tension based on the roll angle in order to articulate the catheter tip in the desired direction. In some embodiments, this is achieved by altering the desired articulation direction by the measured roll amount. 
     Referring now to  FIGS. 17A and 17B , when an articulation command is initiated, the controller first computes the moment required to articulate the catheter tip and then calculates how much to pull or tension the wire to generate the moment.  FIGS. 17A  and  17 B show moments and various angles involved in the computation. If M is the desired moment and m i  is the moment generated from pulling the i th  wire in the catheter, the following equation describes how the desired moment is related to the moments resulting from wire nulls. 
     
       
         
           
             
               
                 
                   
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     As shown in  FIG. 17A , A is the direction of the moment M, and β i  is the direction of the moment resulting from the i th  wire pull. The β i  is related to the angular position of the i th  wire, α i , by a fixed amount π/2. To compute the new articulating moment direction, the measured roll angle, γ, is subtracted out from the original articulating moment direction θ to compensate for the roll. As such, a new articulating direction, θ*, is calculated according to the following rule: 
       θ*=θ−γ  (3)
 
       FIGS. 18A-23B  illustrate systems and methods for integrating a magnetic encoder into a catheter for measuring its roll. These  FIGS. 18A-23B  are illustrated from the perspective of being inside of the catheter—e.g., as if a camera were inside the catheter and looking out through an opening in the distal tip of the catheter. The instrumented catheter would enhance the instinctive driving experience by further improving the accuracy of catheter control. 
     For example,  FIGS. 18A and 18B  illustrate a case where γ is π/2, which means the distal tip of the catheter rolled 90 degrees in the counter clockwise direction. The rotation is around the z-axis, which points out of the screen according to the right hand rule, i.e. cross x-axis and y-axis to get the z-axis.  FIG. 18A  illustrates a scenario in which there is no roll. For example, an incoming command directs the controller to articulate the catheter to the right, that is θ= 3  π/2, and the controller would pull wire  1  on the right side of the catheter. With a 90 degree roll on the catheter, pulling the same wire  1  would not articulate the catheter to the right because wire  1  is now at the top of the catheter. Alternatively, a compensated controller would have a new articulating moment direction θ*=π as shown in  FIG. 18B  and this would enable the controller to pull the correct wire, for example wire  4 , to produce an articulation to the right. 
     Referring now to  FIGS. 19A and 19B , in some embodiments, one or more encoders  1201  may be used to measure catheter roll and thus improve instinctive driving. In general, encoders are non-contact sensors with an infinite number of turns. Encoders come in optical and magnetic varieties. The optical encoder uses an optical emitter-detector pair with a patterned encoder wheel in between to detect the amount of rotation. Alternatively, a magnetic encoder  1201 , shown in  FIGS. 19A and 19B , uses a Hall-effect or magneto-resistive sensor  1202  to detect changes in polarity. Instead of an encoder wheel, a magnetized ring  1200  is used to provide the alternating magnetic poles along the circumference of the ring  1200 . The Hall-effect sensor  1202  can detect the change in polarity as the ring  1200  turns, and the sensor  1202  produces electric pulses for angular measurements. A magnetic encoder  1201  measures relative roll between the magnetic ring  1200  and the Hall-effect sensor  1202 , i.e. the read head. Typically, the sensor  1202  is fixed to a stationary object, and the magnetized ring  1200  rotates with the spinning object or vice versa. 
     Referring now to  FIGS. 20A and 20B , the magnetic ring  1200  and the sensor  1202  may be incorporated into a catheter  1220 , which may also include a distal catheter tip  1204 , two rings  1208   a ,  1208   b  on either side of the ring  1200 , a control ring  1206  and control wires  1210 . The magnetic ring  1200  functions to rotate whenever the catheter  1220  rolls, so that the Hall-effect sensor  1202  can detect the change in roll. The ring  1200  is mounted on rails  1208   a ,  1208   b  on both sides to allow it to spin around freely as the catheter  1220  rolls, and the sensor  1202  is fixed and embedded into the catheter wall. In one embodiment, as shown in  FIG. 20A , the control ring  1206  provides soldering points for the control wires  1210 . Alternatively, the control ring  1206  and the proximal rail  1208   b  may be combined into a single ring to simplify catheter construction, and the control wires  1210  may be directly soldered to the proximal rail  1208   b.    
     In some embodiments, a fluid bearing rather than a mechanical bearing may be used to enable the ring  1200  to freely rotate under gravitational pull in the case in which the rails  1208   a ,  1208   b  cannot significantly reduce friction. For example, the magnetized ring  1200  may be enclosed in a sealed, tube-like structure filled with low viscosity fluid to lower the friction. The operation of the Hall-effect sensor  1202  would not be affected, because it does not need to be in direct contact with the ring  1200 . Alternatively, small-scale dithering may be used to constantly break friction. In some embodiments, a sound wave or any other type of external excitation signal may be used to excite the ring  1200  to break free from either the rail  1208   a ,  1208   b  or the fluid bearing. 
     Referring now to  FIGS. 21A and 21B , in some embodiments, to achieve ring rotation when the catheter rolls, a ring  1230  may be constructed with unbalanced weight distribution, so that it stays upright regardless of catheter roll. As shown in  FIGS. 21A and 21B , the ring  1230  is heavy on one side and light on the other side. Thus, the ring may rotate independently to keep the heavy side down consistently. The size of an enclosing oval  1232 , as shown in  FIG. 21A , demonstrates the weight distribution in the ring  1230 . The weight gradually increases from the top side of the ring to the bottom side of the ring  1230 , as designated by the double-headed arrow. In some embodiments, the weight distribution may change abruptly. In some embodiments, a discontinuous weight change, for example extra weight hanging from one side of the ring  1230 , may maintain the ring  1230  stay upright consistently. 
     In some embodiments, a roll sensor may improve the control and navigation of a robotic catheter. The controller may be able to interpret user inputs quickly, based on the measured roll information and adjust its control output accordingly to increase instinctive driving of the catheter. The catheter may be articulated in the direction desired by the user with all the computation hidden from the user. 
     Alternatively or additionally, a roll sensor may be used for navigation with direct visualization. For example, a camera may be installed on the distal end or tip of a catheter to directly provide a visual image of the surroundings during navigation. For example, U.S. patent application Ser. No. 13/452,029 (U.S. Pub. No. 2012/0296161), filed Apr. 20, 2012, has further information regarding a method to obtain a clear viewing field for a camera, and the contents of this application are hereby incorporated by reference in their entirety. 
     Further, in some embodiments, a roll sensor may measure the absolute roll of the catheter and may be applied to a non-telescoping catheter. If the catheter is instrumented with a camera, the roll sensor can help reorient the camera view so that it displays the field of view right side up. For example, the camera view may not rotate even if the camera itself rotates, and one or more catheter controls may compensate for the catheter roll so that the catheter is manipulated instinctively under the endoscopic camera view. 
       FIGS. 22A and 23A  illustrate a catheter  1240  from the viewpoint of a user. The catheter  1240  is equipped with a camera  1242  at its distal tip and a roll sensor  1244  just proximal to the camera  1242 .  FIG. 23A  illustrates the catheter  1240  rolling 90 degrees in a counter clockwise direction (flat, curved arrow).  FIGS. 22B and 23B  illustrate a left viewing screen  1246  and a right viewing screen  1248 , which display images  1250 ,  1252 ,  1254 ,  1256  to the user to assist in manipulation of the catheter  1240 . In  FIG. 23B , the image  1254  on the left screen  1246  is an uncompensated view, and the image  1256  on the right screen  1248  is a compensated view (e.g. to keep the right side of the catheter  1240  up). The camera view on the left  1254  rotates as the camera  1242  rolls, whereas the view on the right  1256  remains the same independent of camera roll. Further, the catheter controller may recognize the change in roll and make proper adjustments to facilitate navigation. This is illustrated as the D instead of R in the right image  1256  in  FIG. 23B . When it was R, as shown in the image  1252  in  FIG. 22B , pulling the R wire would articulate the catheter  1240  to the right. Due to the catheter/camera roll, the relationship has changed and now the controller needs to pull the D wire instead of the R wire to articulate the catheter  1240  to the right. This modification in control algorithm is transparent to the user, and the controller would make the proper adjustment based on the roll measurement. 
     In some embodiments, a magnetic encoder and sensor may be placed respectively on components of a telescoping catheter, such that relative roll between inner and outer components of the telescoping catheter can be determined. For example, a roll sensor may provide relative roll measurements between the camera, and therefore the instrumented balloon catheter, and the guide catheter. Instead of the absolute roll measurement, γ, as described above, this embodiment uses a relative roll measurement, δ, to obtain a new articulating direction θ t . This new articulation direction makes navigation intuitive from the camera&#39;s perspective. δ measures the roll of the guide catheter with respect to the camera. 
       θ t =θ−δ  (4)
 
     For example, with respect to S measurements, when the camera up direction aligns with the guide catheter&#39;s up direction, the relative roll measurement, γ, is zero; likewise, if the camera rolls π/2 counter clockwise, it is equivalent to the guide catheter roll of −π/2 counter clockwise. 
     For example,  FIGS. 24A and 24B  illustrate a case where the camera is rolled 90 degrees but the catheter roll remains unchanged. The front image in  FIGS. 24A and 24B  is a camera view, and the back image in  FIGS. 24A and 24B  is a catheter view. Both  FIGS. 24A and 24B  describe a user action to articulate the catheter to the right as seen from the camera. Notice the direction of M vector changing as the camera rolls. If the catheter is commanded to articulate right in the camera view, the articulating moment should be generated in the downward direction, i.e. θ=3π/2. This is relatively straightforward in  FIG. 24A , but when the camera rolls, the controller modifies the command according to Equation 4. The resulting direction as shown in  FIG. 14B  is. θ t =2π and the catheter would articulate up as the top wire becomes active. Notice that this would make the catheter articulate right in the current camera view. From the user&#39;s point of view, pressing the right button on the pendant makes the catheter articulate right in the camera view. 
     The above discloses a concept presented here that is for use of instrumented catheters equipped with a relative roll sensor to improve catheter control under direct visual feedback. With the help of such sensor, the user can instinctively drive the catheter while looking at the live video feed from the camera. The visual feedback is easy to interpret and intuitive to understand. As such, integrating catheter motion with camera posture is believed to be an important step toward creating a truly immersive and instinctive catheter driving experience. 
     Referring now to  FIGS. 25A and 25B , a simulated usage of a catheter-based system  1300  for navigating and performing a procedure in a blood vessel is illustrated. The system  1300  is shown advanced through a blood vessel BV toward a branching of the vessel BV into a left branch LB and a right branch RB. The system  1300 , in this embodiment, includes a guide catheter  1302  and an instrumented balloon catheter  1304 , which includes a distal tip camera  1310  and a balloon  1306 . The system includes roll compensation, as disclosed herein. An image  1320  ( FIG. 25B ) may be provided, for example to show directionality of the camera  1310 , such as a camera-up arrow  1312 . 
     The user interface may use a computer or a computer readable storage medium implementing the operation of drive and implementing the various methods described herein. In general, computing systems and/or devices, such as the processor and the user input device, may employ any of a number of computer operating systems, including, but by no means limited to, versions and/or varieties of the Microsoft Windows® operating system, the Unix operating system (e.g., the Solaris® operating system distributed by Oracle Corporation of Redwood Shores, Calif.), the AIX UNIX operating system distributed by International Business Machines of Armonk, N.Y., the Linux operating system, the Mac OS X and iOS operating systems distributed by Apple Inc. of Cupertino, Calif., and the Android operating system developed by the Open Handset Alliance. 
     Computing devices generally include computer-executable instructions, where the instructions may be executable by one or more computing devices such as those listed above. Computer-executable instructions may be compiled or interpreted from computer programs created using a variety of programming languages and/or technologies, including, without limitation, and either alone or in combination, Java™, C, C++, Visual Basic, Java Script, Perl, etc. In general, a processor (e.g., a microprocessor) receives instructions, e.g., from a memory, a computer-readable medium, etc., and executes these instructions, thereby performing one or more processes, including one or more of the processes described herein. Such instructions and other data may be stored and transmitted using a variety of computer-readable media. 
     A computer-readable medium (also referred to as a processor-readable medium) includes any non-transitory (e.g., tangible) medium that participates in providing data (e.g., instructions) that may be read by a computer (e.g., by a processor of a computer). Such a medium may take many forms, including, but not limited to, non-volatile media and volatile media. Non-volatile media may include, for example, optical or magnetic disks and other persistent memory. Volatile media may include, for example, dynamic random access memory (DRAM), which typically constitutes a main memory. Such instructions may be transmitted by one or more transmission media, including coaxial cables, copper wire and fiber optics, including the wires that comprise a system bus coupled to a processor of a computer. Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, an EPROM, a FLASH-EEPROM, any other memory chip or cartridge, or any other medium from which a computer can read. 
     Databases, data repositories or other data stores described herein may include various kinds of mechanisms for storing, accessing, and retrieving various kinds of data, including a hierarchical database, a set of files in a file system, an application database in a proprietary format, a relational database management system (RDBMS), etc. Each such data store is generally included within a computing device employing a computer operating system such as one of those mentioned above, and are accessed via a network in any one or more of a variety of manners. A file system may be accessible from a computer operating system, and may include files stored in various formats. An RDBMS generally employs the Structured Query Language (SQL) in addition to a language for creating, storing, editing, and executing stored procedures, such as the PL/SQL language mentioned above. 
     In some examples, system elements may be implemented as computer-readable instructions (e.g., software) on one or more computing devices (e.g., servers, personal computers, etc.), stored on computer readable media associated therewith (e.g., disks, memories, etc.). A computer program product may comprise such instructions stored on computer readable media for carrying out the functions described herein. 
     The exemplary illustrations are not limited to the previously described examples. Rather, multiple variants and modifications are possible, which also make use of the ideas of the exemplary illustrations and therefore fall within the protective scope. Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. 
     With regard to the processes, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain embodiments, and should in no way be construed so as to limit the claimed invention. 
     Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be upon reading the above description. The scope of the invention should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the arts discussed herein, and that the disclosed systems and methods will be incorporated into such future embodiments. In sum, it should be understood that the invention is capable of modification and variation and is limited only by the following claims. 
     All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those skilled in the art unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as “a,” “an,” “the,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.