Patent Publication Number: US-2021178032-A1

Title: Directed fluidics

Description:
INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATION(S) 
     This application is a continuation of U.S. application Ser. No. 16/212,199, filed Dec. 6, 2018, which claims priority to U.S. Provisional Application No. 62/596,711, filed Dec. 8, 2017, each of which is incorporated herein by reference. Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57. 
    
    
     TECHNICAL FIELD 
     The systems and methods disclosed herein are directed to medical robotics, and more particularly, to robotic medical systems and methods employing directed fluidics during procedures for removal of an object from a patient. 
     BACKGROUND 
     Every year, physicians perform procedures to remove urinary stones from patients&#39; urinary tracts. Urinary stones may include kidney stones, found in the kidneys and ureters, as well as bladder stones, found in the bladder. Such urinary stones may form as a result of concentrated minerals and may cause significant abdominal pain once they reach a size sufficient to impede urine flow through the ureter or urethra. Such stones may be formed from calcium, magnesium, ammonia, uric acid, cysteine, or other compounds. 
     To remove urinary stones from the bladder and ureter, physicians generally use a ureteroscope inserted into the urinary tract through the urethra. Typically, a ureteroscope includes a scope at its distal end to enable visualization of the urinary tract. The procedure may also utilize a lithotomy mechanism to capture or break apart the urinary stones. During the ureteroscopy procedure, one physician may control the position of the ureteroscope and the other physician may control the lithotomy mechanism. To remove large kidney stones from the kidneys, physicians generally use a percutaneous nephrolithotomy (PCNL) technique that includes inserting a nephroscope through the skin to break up and remove the kidney stones. 
     SUMMARY 
     This disclosure relates to systems and techniques for removing an object from a treatment site of a patient, and in particular to methods and systems that employ directed fluidics during an object removal procedure. “Directed fluidics” can refer to methods and systems for providing irrigation and aspiration (e.g., inflow and outflow of fluid) that improve or facilitate an object removal procedure. Directed fluidics can include setting, controlling, or adjusting characteristics of irrigation and/or aspiration to achieve advantageous, beneficial, or desirable fluid flows through a treatment site. 
     In a first aspect, a method of administering fluidics during a medical procedure, includes: inserting a first medical instrument into a treatment site, the first medical instrument comprising a first fluid channel and a second fluid channel; providing irrigation into the treatment site through the first fluid channel of the first medical instrument; providing aspiration from the treatment site through the second fluid channel of the first medical instrument; determining a characteristic of one of the irrigation and the aspiration; and selecting a characteristic of the other of the irrigation and aspiration based on the determined characteristic. 
     The method can include one or more of the following features, in any combination: (a) wherein inserting the first medical instrument into the treatment site comprises advancing the first medical instrument percutaneously into the treatment site; (b) wherein inserting the first medical instrument into the treatment site comprises advancing the first medical instrument through a lumen of a patient into the treatment site; (c) inserting a second medical instrument into the treatment site through a lumen of the patient; (d) percutaneously inserting a second medical instrument into the treatment site; (e) wherein the determined characteristic comprises at least one of an instantaneous flow rate and an average flow rate over a period of time; (f) wherein the selected characteristic comprises at least one of an instantaneous flow rate and an average flow rate over a period of time; (g) wherein the selected characteristic substantially matches the determined characteristic; (h) determining a characteristic of the treatment site, and when the determined characteristic of the treatment site exceeds a threshold value, at least one of: reducing irrigation into the treatment site, increasing aspiration from the treatment site, and providing an alert; (i) wherein the determined characteristic of the treatment site comprises one of a volume of fluid within the treatment site and an internal pressure of the treatment site; (j) moving a distal tip of the first medical instrument in a sweeping motion while providing irrigation or aspiration; (k) wherein at least one of the first medical instrument and the second medical instrument is robotically controlled; (l) performing lithotripsy on an object within the treatment site to break the object into fragments, and aspirating the fragments through the second fluid channel of the first medical instrument; (m) wherein lithotripsy is performed with a second medical instrument; (n) wherein the first medical instrument comprises a steerable medical instrument comprising an articulable distal end; (o) contacting an articulable distal end of the first medical instrument to an object within the treatment site, and providing aspiration through the second fluid channel to hold the object to the articulable distal end; (p) wherein the articulable distal end comprises a pocket configured to hold the object; (q) performing lithotripsy while the object is held in the pocket; (r) moving the first medical instrument to reposition the object within the treatment site; (s) performing lithotripsy on an object within the treatment site to break the object into fragments, and aspirating, during the lithotripsy, through the second fluid channel to remove dust created by the lithotripsy; (t) wherein the additional first fluid channel includes a fluid orifice that directs fluid away from the second medical instrument; (u) wherein irrigation and aspiration are provided at the same time; and/or (v) wherein irrigation and aspiration are not provided at the same time. 
     In another aspect, a system for performing a medical procedure can include: a first medical instrument configured to be inserted into a treatment site, the first instrument including a first fluid channel and a second fluid channel; a vacuum connected to one of the first fluid channel and the second fluid channel and configured to apply a negative pressure to provide aspiration from the treatment site; a pump coupled to an irrigation source and the other of the first fluid channel and the second fluid channel, the pump configured to provide irrigation to the treatment site; and a fluidics control system coupled to the vacuum and the pump, the fluidics control system comprising one or more processors configured to: determine a characteristic of one of the irrigation and the aspiration, and control a characteristic of at least one of the pump or the vacuum based on the determined characteristic. 
     The system can include one or more of the following features in any combination: (a) wherein the first medical instrument is configured to be inserted through a lumen of a patient into the treatment site; (b) wherein the first medical instrument is configured to be inserted percutaneously into the treatment site; (c) wherein further comprising a second medical instrument is configured to be inserted through a lumen of a patient into the treatment site; (d) comprising a second medical instrument that is configured to be inserted percutaneously into the treatment site; (e) wherein the first medical instrument further comprises a flow rate sensor positioned in the first fluid channel, and wherein an output of the flow rate sensor is connected to the fluidics control system; (f) wherein the second first medical instrument further comprises a flow rate sensor positioned in the second fluid channel, and wherein an output of the flow rate sensor is connected to the fluidics control system; (g) wherein the first medical instrument further comprises a pressure sensor disposed to measure an internal pressure of the treatment site, an output of the pressure sensor connected to the fluidics control system, and wherein the one or more processors are further configured to control at least one of the pump or the vacuum to adjust at least one of the aspiration and the irrigation based on the measured internal pressure of the treatment site; (h) a second medical instrument configured to be inserted into the treatment site, wherein the second medical instrument further comprises a pressure sensor disposed to measure an internal pressure of the treatment site, an output of the pressure sensor connected to the fluidics control system, and wherein the one or more processors are further configured to control at least one of the pump or the vacuum to adjust at least one of the aspiration and irrigation based on the measured internal pressure of the treatment site; and/or (i) wherein the first medical instrument comprises an articulable distal end. 
     In another aspect, a medical device can include: an articulable elongate body extending along an axis to a distal end; a first fluid channel extending along the axis, the first fluid channel terminating in a first fluid orifice formed in a distal face of the distal end; and at least one additional fluid channel formed through the elongate body, the at least one additional fluid channel terminating in at least one additional fluid exit orifice formed in a radial surface of the elongate body proximal the distal end. 
     The medical device can include one or more of the following features in any combination: (a) a pocket formed in the distal face; (b) wherein the pocket is configured to at least partially receive an object to be removed during a medical procedure; (c) wherein the at least one additional channel annularly surrounds the first fluid channel; (d) wherein the at least one additional fluid orifice comprises additional fluid orifices positioned around the axis; (e) wherein the at least one additional channel comprises additional channels positioned radially around the first fluid channel; (f) wherein each of the four additional fluid channels terminates at an additional fluid orifice positioned radially around the axis; and/or (g) at least one pull wire for articulating the elongate body. 
     In another aspect, a non-transitory computer readable storage medium can include stored thereon instructions that, when executed, cause a processor of a device to at least: determine a characteristic of at least one of irrigation into a treatment site through a first channel of a first medical instrument and an aspiration from the treatment site through a second channel of the first medical instrument; and select a characteristic of at least one of the irrigation and the aspiration based on the determined characteristic. 
     The non-transitory computer readable storage medium can include one or more of the following features in any combination: (a) wherein the determined characteristic comprises at least one of an instantaneous flow rate and an average flow rate over a period of time; (b) wherein the selected characteristic comprises at least one of an instantaneous flow rate and an average flow rate over a period of time; (c) wherein the selected characteristic substantially matches the determined characteristic; (d) wherein the instructions, when executed further cause the processor to determine a characteristic of the treatment site, and when the determined characteristic of the treatment site exceeds a threshold value, at least one of: reduce irrigation into the treatment site, increase aspiration from the treatment site, and provide an alert; (e) wherein the determined characteristic of the treatment site comprises one of a volume of fluid within the treatment site and an internal pressure of the treatment site; (f) wherein the instructions, when executed further cause the processor to: perform lithotripsy with a second medical instrument on an object within the treatment site to break the object into fragments, and aspirate the fragments through the second fluid channel of the second first medical instrument; (g) wherein the instructions, when executed further cause the processor to: perform lithotripsy with a second medical instrument on an object within the treatment site to break the object into fragments, and aspirate, during the lithotripsy, through the second fluid channel of the second first medical instrument to remove dust created by the lithotripsy; (h) wherein the instructions, when executed further cause the processor to provide irrigation and aspiration at the same time; and/or (i) wherein irrigation and aspiration are not provided at the same time. 
     In another aspect, a method of administering fluidics during the removal of an object from a patient can include: advancing a first medical instrument through a lumen of a patient toward a treatment site containing an object to be removed, the first medical instrument comprising a first fluid channel for providing irrigation through a first aperture positioned on a remotely articulable distal tip, the first aperture configured to provide irrigation in a first fluid flow direction; inserting a second medical instrument percutaneously into the treatment site, the second medical instrument comprising a second fluid channel for providing aspiration through a second aperture of the second fluid channel; providing irrigation into the treatment site with the first medical instrument through the first aperture; providing aspiration from the treatment site through the second aperture of the second fluid channel of the second medical instrument; and remotely manipulating the distal tip of the first medical instrument such that the first fluid direction is oriented towards the second aperture. 
     The method can include one or more of the following features in any combination: (a) determining the position of the second aperture within the treatment site, and wherein manipulating the distal tip comprises automatically manipulating the distal tip based on the determined position of the second aperture within the treatment site; (b) wherein a nephroscope comprises the second medical instrument and a lithotripter, and wherein the method further comprises: contacting the lithotripter to the object, performing lithotripsy to break the object into fragments, and aspirating the fragments with the suction tube; and/or (c) moving a distal tip of the first medical instrument in a sweeping motion while providing irrigation through the first medical instrument. 
     Although this disclosure is largely described with respect to example use cases of ureteroscopy, percutaneous nephrolithotomy (PCNL), and the removal of urinary stones and stone fragments, this disclosure may be equally applicable to other surgical/medical operations concerned with the removal of objects from various treatment sites of the patient, including any object that can be safely removed via a patient cavity (e.g., the esophagus, ureter, intestine, etc.) or via percutaneous access, such as gallbladder stone removal or lung (pulmonary/transthoracic) tumor biopsy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosed aspects will hereinafter be described in conjunction with the appended drawings, provided to illustrate and not to limit the disclosed aspects, wherein like designations denote like elements. 
         FIG. 1  illustrates an embodiment of a cart-based robotic system arranged for diagnostic and/or therapeutic bronchoscopy procedure(s). 
         FIG. 2  depicts further aspects of the robotic system of  FIG. 1 . 
         FIG. 3  illustrates an embodiment of the robotic system of  FIG. 1  arranged for ureteroscopy. 
         FIG. 4  illustrates an embodiment of the robotic system of  FIG. 1  arranged for a vascular procedure. 
         FIG. 5  illustrates an embodiment of a table-based robotic system arranged for a bronchoscopy procedure. 
         FIG. 6  provides an alternative view of the robotic system of  FIG. 5 . 
         FIG. 7  illustrates an example system configured to stow robotic arm(s). 
         FIG. 8  illustrates an embodiment of a table-based robotic system configured for a ureteroscopy procedure. 
         FIG. 9  illustrates an embodiment of a table-based robotic system configured for a laparoscopic procedure. 
         FIG. 10  illustrates an embodiment of the table-based robotic system of  FIGS. 5-9  with pitch or tilt adjustment. 
         FIG. 11  provides a detailed illustration of the interface between the table and the column of the table-based robotic system of  FIGS. 5-10 . 
         FIG. 12  illustrates an exemplary instrument driver. 
         FIG. 13  illustrates an exemplary medical instrument with a paired instrument driver. 
         FIG. 14  illustrates an alternative design for an instrument driver and instrument where the axes of the drive units are parallel to the axis of the elongated shaft of the instrument. 
         FIG. 15  depicts a block diagram illustrating a localization system that estimates a location of one or more elements of the robotic systems of  FIGS. 1-10 , such as the location of the instrument of  FIGS. 13 and 14 , in accordance to an example embodiment. 
         FIG. 16  illustrates an example procedure for removing an object from a kidney using a first medical instrument inserted into the kidney percutaneously. 
         FIG. 17  illustrates an example procedure for removing an object from a kidney using a first medical instrument inserted into the kidney through a patient lumen, a second medical instrument inserted into the kidney percutaneously, and directed fluidics. 
         FIG. 18  illustrates another example procedure for removing an object from a kidney using a first medical instrument inserted into the kidney through a patient lumen, a second medical instrument inserted into the kidney percutaneously, and directed fluidics. 
         FIG. 19  illustrates another example procedure for removing an object from a kidney using a first medical instrument inserted into the kidney through a patient lumen, a second medical instrument inserted into the kidney percutaneously, and directed fluidics. 
         FIG. 20  illustrates a detailed view of a distal tip of a first medical instrument providing irrigation and a distal tip of a second medical instrument providing aspiration during an object removal procedure. 
         FIG. 21A  illustrates a detailed view of a distal tip of a first medical instrument providing irrigation and a distal tip of a second medical instrument providing irrigation and aspiration during an object removal procedure. 
         FIG. 21B  illustrates a detailed view of a distal tip of a first medical instrument performing lithotomy and a distal tip of a second medical instrument providing irrigation and aspiration during an object removal procedure. 
         FIG. 22A  is a flowchart illustrating an embodiment of a method for directed fluidics during an object removal procedure. 
         FIG. 22B  is a flowchart illustrating an embodiment of another method for directed fluidics during an object removal procedure. 
         FIG. 23  is a flowchart illustrating an embodiment of another method for directed fluidics during an object removal procedure. 
         FIG. 24  is a flowchart illustrating an embodiment of a method for holding and repositioning an object using directed fluidics during an object removal procedure. 
         FIG. 25  is a block diagram illustrating an embodiment of a system for directed fluidics. 
         FIG. 26A  is a perspective view of a distal end of a medical instrument configured to provide aspiration and irrigation during an object removal procedure. 
         FIG. 26B  is a cross-sectional view of the distal end of the medical instrument of  FIG. 26A , illustrating the irrigation and aspiration channels within the medical instrument. 
         FIG. 27  illustrates an embodiment of a robotic system arranged for performing an object removal procedure using directed fluidics. 
     
    
    
     DETAILED DESCRIPTION 
     1. Overview. 
     Aspects of the present disclosure may be integrated into a robotically-enabled medical system capable of performing a variety of medical procedures, including both minimally invasive, such as laparoscopy, and non-invasive, such as endoscopy, procedures. Among endoscopy procedures, the system may be capable of performing bronchoscopy, ureteroscopy, gastroscopy, etc. 
     In addition to performing the breadth of procedures, the system may provide additional benefits, such as enhanced imaging and guidance to assist the physician. Additionally, the system may provide the physician with the ability to perform the procedure from an ergonomic position without the need for awkward arm motions and positions. Still further, the system may provide the physician with the ability to perform the procedure with improved ease of use such that one or more of the instruments of the system can be controlled by a single user. 
     Various embodiments will be described below in conjunction with the drawings for purposes of illustration. It should be appreciated that many other implementations of the disclosed concepts are possible, and various advantages can be achieved with the disclosed implementations. Headings are included herein for reference and to aid in locating various sections. These headings are not intended to limit the scope of the concepts described with respect thereto. Such concepts may have applicability throughout the entire specification. 
     A. Robotic System—Cart. 
     The robotically-enabled medical system may be configured in a variety of ways depending on the particular procedure.  FIG. 1  illustrates an embodiment of a cart-based robotically-enabled system  10  arranged for a diagnostic and/or therapeutic bronchoscopy procedure. During a bronchoscopy, the system  10  may comprise a cart  11  having one or more robotic arms  12  to deliver a medical instrument, such as a steerable endoscope  13 , which may be a procedure-specific bronchoscope for bronchoscopy, to a natural orifice access point (i.e., the mouth of the patient positioned on a table in the present example) to deliver diagnostic and/or therapeutic tools. As shown, the cart  11  may be positioned proximate to the patient&#39;s upper torso in order to provide access to the access point. Similarly, the robotic arms  12  may be actuated to position the bronchoscope relative to the access point. The arrangement in  FIG. 1  may also be utilized when performing a gastro-intestinal (GI) procedure with a gastroscope, a specialized endoscope for GI procedures.  FIG. 2  depicts an example embodiment of the cart in greater detail. 
     With continued reference to  FIG. 1 , once the cart  11  is properly positioned, the robotic arms  12  may insert the steerable endoscope  13  into the patient robotically, manually, or a combination thereof. As shown, the steerable endoscope  13  may comprise at least two telescoping parts, such as an inner leader portion and an outer sheath portion, each portion coupled to a separate instrument driver from the set of instrument drivers  28 , each instrument driver coupled to the distal end of an individual robotic arm. This linear arrangement of the instrument drivers  28 , which facilitates coaxially aligning the leader portion with the sheath portion, creates a “virtual rail”  29  that may be repositioned in space by manipulating the one or more robotic arms  12  into different angles and/or positions. The virtual rails described herein are depicted in the Figures using dashed lines, and accordingly the dashed lines do not depict any physical structure of the system. Translation of the instrument drivers  28  along the virtual rail  29  telescopes the inner leader portion relative to the outer sheath portion or advances or retracts the endoscope  13  from the patient. The angle of the virtual rail  29  may be adjusted, translated, and pivoted based on clinical application or physician preference. For example, in bronchoscopy, the angle and position of the virtual rail  29  as shown represents a compromise between providing physician access to the endoscope  13  while minimizing friction that results from bending the endoscope  13  into the patient&#39;s mouth. 
     The endoscope  13  may be directed down the patient&#39;s trachea and lungs after insertion using precise commands from the robotic system until reaching the target destination or operative site. In order to enhance navigation through the patient&#39;s lung network and/or reach the desired target, the endoscope  13  may be manipulated to telescopically extend the inner leader portion from the outer sheath portion to obtain enhanced articulation and greater bend radius. The use of separate instrument drivers  28  also allows the leader portion and sheath portion to be driven independent of each other. 
     For example, the endoscope  13  may be directed to deliver a biopsy needle to a target, such as, for example, a lesion or nodule within the lungs of a patient. The needle may be deployed down a working channel that runs the length of the endoscope to obtain a tissue sample to be analyzed by a pathologist. Depending on the pathology results, additional tools may be deployed down the working channel of the endoscope for additional biopsies. After identifying a nodule to be malignant, the endoscope  13  may endoscopically deliver tools to resect the potentially cancerous tissue. In some instances, diagnostic and therapeutic treatments may need to be delivered in separate procedures. In those circumstances, the endoscope  13  may also be used to deliver a fiducial to “mark” the location of the target nodule as well. In other instances, diagnostic and therapeutic treatments may be delivered during the same procedure. 
     The system  10  may also include a movable tower  30 , which may be connected via support cables to the cart  11  to provide support for controls, electronics, fluidics, optics, sensors, and/or power to the cart  11 . Placing such functionality in the tower  30  allows for a smaller form factor cart  11  that may be more easily adjusted and/or repositioned by an operating physician and his/her staff. Additionally, the division of functionality between the cart/table and the support tower  30  reduces operating room clutter and facilitates improving clinical workflow. While the cart  11  may be positioned close to the patient, the tower  30  may be stowed in a remote location to stay out of the way during a procedure. 
     In support of the robotic systems described above, the tower  30  may include component(s) of a computer-based control system that stores computer program instructions, for example, within a non-transitory computer-readable storage medium such as a persistent magnetic storage drive, solid state drive, etc. The execution of those instructions, whether the execution occurs in the tower  30  or the cart  11 , may control the entire system or sub-system(s) thereof. For example, when executed by a processor of the computer system, the instructions may cause the components of the robotics system to actuate the relevant carriages and arm mounts, actuate the robotics arms, and control the medical instruments. For example, in response to receiving the control signal, the motors in the joints of the robotics arms may position the arms into a certain posture. 
     The tower  30  may also include a pump, flow meter, valve control, and/or fluid access in order to provide controlled irrigation and aspiration capabilities to system that may be deployed through the endoscope  13 . These components may also be controlled using the computer system of tower  30 . In some embodiments, irrigation and aspiration capabilities may be delivered directly to the endoscope  13  through separate cable(s). 
     The tower  30  may include a voltage and surge protector designed to provide filtered and protected electrical power to the cart  11 , thereby avoiding placement of a power transformer and other auxiliary power components in the cart  11 , resulting in a smaller, more moveable cart  11 . 
     The tower  30  may also include support equipment for the sensors deployed throughout the robotic system  10 . For example, the tower  30  may include opto-electronics equipment for detecting, receiving, and processing data received from the optical sensors or cameras throughout the robotic system  10 . In combination with the control system, such opto-electronics equipment may be used to generate real-time images for display in any number of consoles deployed throughout the system, including in the tower  30 . Similarly, the tower  30  may also include an electronic subsystem for receiving and processing signals received from deployed electromagnetic (EM) sensors. The tower  30  may also be used to house and position an EM field generator for detection by EM sensors in or on the medical instrument. 
     The tower  30  may also include a console  31  in addition to other consoles available in the rest of the system, e.g., console mounted on top of the cart. The console  31  may include a user interface and a display screen, such as a touchscreen, for the physician operator. Consoles in system  10  are generally designed to provide both robotic controls as well as pre-operative and real-time information of the procedure, such as navigational and localization information of the endoscope  13 . When the console  31  is not the only console available to the physician, it may be used by a second operator, such as a nurse, to monitor the health or vitals of the patient and the operation of system, as well as provide procedure-specific data, such as navigational and localization information. 
     The tower  30  may be coupled to the cart  11  and endoscope  13  through one or more cables or connections (not shown). In some embodiments, the support functionality from the tower  30  may be provided through a single cable to the cart  11 , simplifying and de-cluttering the operating room. In other embodiments, specific functionality may be coupled in separate cabling and connections. For example, while power may be provided through a single power cable to the cart, the support for controls, optics, fluidics, and/or navigation may be provided through a separate cable. 
       FIG. 2  provides a detailed illustration of an embodiment of the cart from the cart-based robotically-enabled system shown in  FIG. 1 . The cart  11  generally includes an elongated support structure  14  (often referred to as a “column”), a cart base  15 , and a console  16  at the top of the column  14 . The column  14  may include one or more carriages, such as a carriage  17  (alternatively “arm support”) for supporting the deployment of one or more robotic arms  12  (three shown in  FIG. 2 ). The carriage  17  may include individually configurable arm mounts that rotate along a perpendicular axis to adjust the base of the robotic arms  12  for better positioning relative to the patient. The carriage  17  also includes a carriage interface  19  that allows the carriage  17  to vertically translate along the column  14 . 
     The carriage interface  19  is connected to the column  14  through slots, such as slot  20 , that are positioned on opposite sides of the column  14  to guide the vertical translation of the carriage  17 . The slot  20  contains a vertical translation interface to position and hold the carriage at various vertical heights relative to the cart base  15 . Vertical translation of the carriage  17  allows the cart  11  to adjust the reach of the robotic arms  12  to meet a variety of table heights, patient sizes, and physician preferences. Similarly, the individually configurable arm mounts on the carriage  17  allow the robotic arm base  21  of robotic arms  12  to be angled in a variety of configurations. 
     In some embodiments, the slot  20  may be supplemented with slot covers that are flush and parallel to the slot surface to prevent dirt and fluid ingress into the internal chambers of the column  14  and the vertical translation interface as the carriage  17  vertically translates. The slot covers may be deployed through pairs of spring spools positioned near the vertical top and bottom of the slot  20 . The covers are coiled within the spools until deployed to extend and retract from their coiled state as the carriage  17  vertically translates up and down. The spring-loading of the spools provides force to retract the cover into a spool when carriage  17  translates towards the spool, while also maintaining a tight seal when the carriage  17  translates away from the spool. The covers may be connected to the carriage  17  using, for example, brackets in the carriage interface  19  to ensure proper extension and retraction of the cover as the carriage  17  translates. 
     The column  14  may internally comprise mechanisms, such as gears and motors, that are designed to use a vertically aligned lead screw to translate the carriage  17  in a mechanized fashion in response to control signals generated in response to user inputs, e.g., inputs from the console  16 . 
     The robotic arms  12  may generally comprise robotic arm bases  21  and end effectors  22 , separated by a series of linkages  23  that are connected by a series of joints  24 , each joint comprising an independent actuator, each actuator comprising an independently controllable motor. Each independently controllable joint represents an independent degree of freedom available to the robotic arm. Each of the arms  12  have seven joints, and thus provide seven degrees of freedom. A multitude of joints result in a multitude of degrees of freedom, allowing for “redundant” degrees of freedom. Redundant degrees of freedom allow the robotic arms  12  to position their respective end effectors  22  at a specific position, orientation, and trajectory in space using different linkage positions and joint angles. This allows for the system to position and direct a medical instrument from a desired point in space while allowing the physician to move the arm joints into a clinically advantageous position away from the patient to create greater access, while avoiding arm collisions. 
     The cart base  15  balances the weight of the column  14 , carriage  17 , and arms  12  over the floor. Accordingly, the cart base  15  houses heavier components, such as electronics, motors, power supply, as well as components that either enable movement and/or immobilize the cart. For example, the cart base  15  includes rollable wheel-shaped casters  25  that allow for the cart to easily move around the room prior to a procedure. After reaching the appropriate position, the casters  25  may be immobilized using wheel locks to hold the cart  11  in place during the procedure. 
     Positioned at the vertical end of column  14 , the console  16  allows for both a user interface for receiving user input and a display screen (or a dual-purpose device such as, for example, a touchscreen  26 ) to provide the physician user with both pre-operative and intra-operative data. Potential pre-operative data on the touchscreen  26  may include pre-operative plans, navigation and mapping data derived from pre-operative computerized tomography (CT) scans, and/or notes from pre-operative patient interviews. Intra-operative data on display may include optical information provided from the tool, sensor and coordinate information from sensors, as well as vital patient statistics, such as respiration, heart rate, and/or pulse. The console  16  may be positioned and tilted to allow a physician to access the console from the side of the column  14  opposite carriage  17 . From this position, the physician may view the console  16 , robotic arms  12 , and patient while operating the console  16  from behind the cart  11 . As shown, the console  16  also includes a handle  27  to assist with maneuvering and stabilizing cart  11 . 
       FIG. 3  illustrates an embodiment of a robotically-enabled system  10  arranged for ureteroscopy. In a ureteroscopic procedure, the cart  11  may be positioned to deliver a ureteroscope  32 , a procedure-specific endoscope designed to traverse a patient&#39;s urethra and ureter, to the lower abdominal area of the patient. In ureteroscopy, it may be desirable for the ureteroscope  32  to be directly aligned with the patient&#39;s urethra to reduce friction and forces on the sensitive anatomy in the area. As shown, the cart  11  may be aligned at the foot of the table to allow the robotic arms  12  to position the ureteroscope  32  for direct linear access to the patient&#39;s urethra. From the foot of the table, the robotic arms  12  may insert the ureteroscope  32  along the virtual rail  33  directly into the patient&#39;s lower abdomen through the urethra. 
     After insertion into the urethra, using similar control techniques as in bronchoscopy, the ureteroscope  32  may be navigated into the bladder, ureters, and/or kidneys for diagnostic and/or therapeutic applications. For example, the ureteroscope  32  may be directed into the ureter and kidneys to break up kidney stone build up using laser or ultrasonic lithotripsy device deployed down the working channel of the ureteroscope  32 . After lithotripsy is complete, the resulting stone fragments may be removed using baskets deployed down the ureteroscope  32 . 
       FIG. 4  illustrates an embodiment of a robotically-enabled system similarly arranged for a vascular procedure. In a vascular procedure, the system  10  may be configured such the cart  11  may deliver a medical instrument  34 , such as a steerable catheter, to an access point in the femoral artery in the patient&#39;s leg. The femoral artery presents both a larger diameter for navigation as well as relatively less circuitous and tortuous path to the patient&#39;s heart, which simplifies navigation. As in a ureteroscopic procedure, the cart  11  may be positioned towards the patient&#39;s legs and lower abdomen to allow the robotic arms  12  to provide a virtual rail  35  with direct linear access to the femoral artery access point in the patient&#39;s thigh/hip region. After insertion into the artery, the medical instrument  34  may be directed and inserted by translating the instrument drivers  28 . Alternatively, the cart may be positioned around the patient&#39;s upper abdomen in order to reach alternative vascular access points, such as, for example, the carotid and brachial arteries near the shoulder and wrist. 
     B. Robotic System—Table. 
     Embodiments of the robotically-enabled medical system may also incorporate the patient&#39;s table. Incorporation of the table reduces the amount of capital equipment within the operating room by removing the cart, which allows greater access to the patient.  FIG. 5  illustrates an embodiment of such a robotically-enabled system arranged for a bronchoscopy procedure. System  36  includes a support structure or column  37  for supporting platform  38  (shown as a “table” or “bed”) over the floor. Much like in the cart-based systems, the end effectors of the robotic arms  39  of the system  36  comprise instrument drivers  42  that are designed to manipulate an elongated medical instrument, such as a bronchoscope  40  in  FIG. 5 , through or along a virtual rail  41  formed from the linear alignment of the instrument drivers  42 . In practice, a C-arm for providing fluoroscopic imaging may be positioned over the patient&#39;s upper abdominal area by placing the emitter and detector around table  38 . 
       FIG. 6  provides an alternative view of the system  36  without the patient and medical instrument for discussion purposes. As shown, the column  37  may include one or more carriages  43  shown as ring-shaped in the system  36 , from which the one or more robotic arms  39  may be based. The carriages  43  may translate along a vertical column interface  44  that runs the length of the column  37  to provide different vantage points from which the robotic arms  39  may be positioned to reach the patient. The carriage(s)  43  may rotate around the column  37  using a mechanical motor positioned within the column  37  to allow the robotic arms  39  to have access to multiples sides of the table  38 , such as, for example, both sides of the patient. In embodiments with multiple carriages, the carriages may be individually positioned on the column and may translate and/or rotate independent of the other carriages. While carriages  43  need not surround the column  37  or even be circular, the ring-shape as shown facilitates rotation of the carriages  43  around the column  37  while maintaining structural balance. Rotation and translation of the carriages  43  allows the system to align the medical instruments, such as endoscopes and laparoscopes, into different access points on the patient. 
     The arms  39  may be mounted on the carriages through a set of arm mounts  45  comprising a series of joints that may individually rotate and/or telescopically extend to provide additional configurability to the robotic arms  39 . Additionally, the arm mounts  45  may be positioned on the carriages  43  such that, when the carriages  43  are appropriately rotated, the arm mounts  45  may be positioned on either the same side of table  38  (as shown in  FIG. 6 ), on opposite sides of table  38  (as shown in  FIG. 9 ), or on adjacent sides of the table  38  (not shown). 
     The column  37  structurally provides support for the table  38 , and a path for vertical translation of the carriages. Internally, the column  37  may be equipped with lead screws for guiding vertical translation of the carriages, and motors to mechanize the translation of said carriages based the lead screws. The column  37  may also convey power and control signals to the carriage  43  and robotic arms  39  mounted thereon. 
     The table base  46  serves a similar function as the cart base  15  in cart  11  shown in  FIG. 2 , housing heavier components to balance the table/bed  38 , the column  37 , the carriages  43 , and the robotic arms  39 . The table base  46  may also incorporate rigid casters to provide stability during procedures. Deployed from the bottom of the table base  46 , the casters may extend in opposite directions on both sides of the base  46  and retract when the system  36  needs to be moved. 
     Continuing with  FIG. 6 , the system  36  may also include a tower (not shown) that divides the functionality of system  36  between table and tower to reduce the form factor and bulk of the table. As in earlier disclosed embodiments, the tower may provide a variety of support functionalities to table, such as processing, computing, and control capabilities, power, fluidics, and/or optical and sensor processing. The tower may also be movable to be positioned away from the patient to improve physician access and de-clutter the operating room. Additionally, placing components in the tower allows for more storage space in the table base for potential stowage of the robotic arms. The tower may also include a console that provides both a user interface for user input, such as keyboard and/or pendant, as well as a display screen (or touchscreen) for pre-operative and intra-operative information, such as real-time imaging, navigation, and tracking information. 
     In some embodiments, a table base may stow and store the robotic arms when not in use.  FIG. 7  illustrates a system  47  that stows robotic arms in an embodiment of the table-based system. In system  47 , carriages  48  may be vertically translated into base  49  to stow robotic arms  50 , arm mounts  51 , and the carriages  48  within the base  49 . Base covers  52  may be translated and retracted open to deploy the carriages  48 , arm mounts  51 , and arms  50  around column  53 , and closed to stow to protect them when not in use. The base covers  52  may be sealed with a membrane  54  along the edges of its opening to prevent dirt and fluid ingress when closed. 
       FIG. 8  illustrates an embodiment of a robotically-enabled table-based system configured for a ureteroscopy procedure. In ureteroscopy, the table  38  may include a swivel portion  55  for positioning a patient off-angle from the column  37  and table base  46 . The swivel portion  55  may rotate or pivot around a pivot point (e.g., located below the patient&#39;s head) in order to position the bottom portion of the swivel portion  55  away from the column  37 . For example, the pivoting of the swivel portion  55  allows a C-arm (not shown) to be positioned over the patient&#39;s lower abdomen without competing for space with the column (not shown) below table  38 . By rotating the carriage  35  (not shown) around the column  37 , the robotic arms  39  may directly insert a ureteroscope  56  along a virtual rail  57  into the patient&#39;s groin area to reach the urethra. In ureteroscopy, stirrups  58  may also be fixed to the swivel portion  55  of the table  38  to support the position of the patient&#39;s legs during the procedure and allow clear access to the patient&#39;s groin area. 
     In a laparoscopic procedure, through small incision(s) in the patient&#39;s abdominal wall, minimally invasive instruments (elongated in shape to accommodate the size of the one or more incisions) may be inserted into the patient&#39;s anatomy. After inflation of the patient&#39;s abdominal cavity, the instruments, often referred to as laparoscopes, may be directed to perform surgical tasks, such as grasping, cutting, ablating, suturing, etc.  FIG. 9  illustrates an embodiment of a robotically-enabled table-based system configured for a laparoscopic procedure. As shown in  FIG. 9 , the carriages  43  of the system  36  may be rotated and vertically adjusted to position pairs of the robotic arms  39  on opposite sides of the table  38 , such that laparoscopes  59  may be positioned using the arm mounts  45  to be passed through minimal incisions on both sides of the patient to reach his/her abdominal cavity. 
     To accommodate laparoscopic procedures, the robotically-enabled table system may also tilt the platform to a desired angle.  FIG. 10  illustrates an embodiment of the robotically-enabled medical system with pitch or tilt adjustment. As shown in  FIG. 10 , the system  36  may accommodate tilt of the table  38  to position one portion of the table at a greater distance from the floor than the other. Additionally, the arm mounts  45  may rotate to match the tilt such that the arms  39  maintain the same planar relationship with table  38 . To accommodate steeper angles, the column  37  may also include telescoping portions  60  that allow vertical extension of column  37  to keep the table  38  from touching the floor or colliding with base  46 . 
       FIG. 11  provides a detailed illustration of the interface between the table  38  and the column  37 . Pitch rotation mechanism  61  may be configured to alter the pitch angle of the table  38  relative to the column  37  in multiple degrees of freedom. The pitch rotation mechanism  61  may be enabled by the positioning of orthogonal axes  1 ,  2  at the column-table interface, each axis actuated by a separate motor  3 ,  4  responsive to an electrical pitch angle command. Rotation along one screw  5  would enable tilt adjustments in one axis  1 , while rotation along the other screw  6  would enable tilt adjustments along the other axis  2 . 
     For example, pitch adjustments are particularly useful when trying to position the table in a Trendelenburg position, i.e., position the patient&#39;s lower abdomen at a higher position from the floor than the patient&#39;s lower abdomen, for lower abdominal surgery. The Trendelenburg position causes the patient&#39;s internal organs to slide towards his/her upper abdomen through the force of gravity, clearing out the abdominal cavity for minimally invasive tools to enter and perform lower abdominal surgical procedures, such as laparoscopic prostatectomy. 
     C. Instrument Driver &amp; Interface. 
     The end effectors of the system&#39;s robotic arms comprise (i) an instrument driver (alternatively referred to as “instrument drive mechanism” or “instrument device manipulator”) that incorporate electro-mechanical means for actuating the medical instrument and (ii) a removable or detachable medical instrument which may be devoid of any electro-mechanical components, such as motors. This dichotomy may be driven by the need to sterilize medical instruments used in medical procedures, and the inability to adequately sterilize expensive capital equipment due to their intricate mechanical assemblies and sensitive electronics. Accordingly, the medical instruments may be designed to be detached, removed, and interchanged from the instrument driver (and thus the system) for individual sterilization or disposal by the physician or the physician&#39;s staff. In contrast, the instrument drivers need not be changed or sterilized, and may be draped for protection. 
       FIG. 12  illustrates an example instrument driver. Positioned at the distal end of a robotic arm, instrument driver  62  comprises of one or more drive units  63  arranged with parallel axes to provide controlled torque to a medical instrument via drive shafts  64 . Each drive unit  63  comprises an individual drive shaft  64  for interacting with the instrument, a gear head  65  for converting the motor shaft rotation to a desired torque, a motor  66  for generating the drive torque, an encoder  67  to measure the speed of the motor shaft and provide feedback to the control circuitry, and control circuitry  68  for receiving control signals and actuating the drive unit. Each drive unit  63  being independent controlled and motorized, the instrument driver  62  may provide multiple (four as shown in  FIG. 12 ) independent drive outputs to the medical instrument. In operation, the control circuitry  68  would receive a control signal, transmit a motor signal to the motor  66 , compare the resulting motor speed as measured by the encoder  67  with the desired speed, and modulate the motor signal to generate the desired torque. 
     For procedures that require a sterile environment, the robotic system may incorporate a drive interface, such as a sterile adapter connected to a sterile drape, that sits between the instrument driver and the medical instrument. The chief purpose of the sterile adapter is to transfer angular motion from the drive shafts of the instrument driver to the drive inputs of the instrument while maintaining physical separation, and thus sterility, between the drive shafts and drive inputs. Accordingly, an example sterile adapter may comprise of a series of rotational inputs and outputs intended to be mated with the drive shafts of the instrument driver and drive inputs on the instrument. Connected to the sterile adapter, the sterile drape, comprised of a thin, flexible material such as transparent or translucent plastic, is designed to cover the capital equipment, such as the instrument driver, robotic arm, and cart (in a cart-based system) or table (in a table-based system). Use of the drape would allow the capital equipment to be positioned proximate to the patient while still being located in an area not requiring sterilization (i.e., non-sterile field). On the other side of the sterile drape, the medical instrument may interface with the patient in an area requiring sterilization (i.e., sterile field). 
     D. Medical Instrument. 
       FIG. 13  illustrates an example medical instrument with a paired instrument driver. Like other instruments designed for use with a robotic system, medical instrument  70  comprises an elongated shaft  71  (or elongate body) and an instrument base  72 . The instrument base  72 , also referred to as an “instrument handle” due to its intended design for manual interaction by the physician, may generally comprise rotatable drive inputs  73 , e.g., receptacles, pulleys or spools, that are designed to be mated with drive outputs  74  that extend through a drive interface on instrument driver  75  at the distal end of robotic arm  76 . When physically connected, latched, and/or coupled, the mated drive inputs  73  of instrument base  72  may share axes of rotation with the drive outputs  74  in the instrument driver  75  to allow the transfer of torque from drive outputs  74  to drive inputs  73 . In some embodiments, the drive outputs  74  may comprise splines that are designed to mate with receptacles on the drive inputs  73 . 
     The elongated shaft  71  is designed to be delivered through either an anatomical opening or lumen, e.g., as in endoscopy, or a minimally invasive incision, e.g., as in laparoscopy. The elongated shaft  66  may be either flexible (e.g., having properties similar to an endoscope) or rigid (e.g., having properties similar to a laparoscope) or contain a customized combination of both flexible and rigid portions. When designed for laparoscopy, the distal end of a rigid elongated shaft may be connected to an end effector comprising a jointed wrist formed from a clevis with an axis of rotation and a surgical tool, such as, for example, a grasper or scissors, that may be actuated based on force from the tendons as the drive inputs rotate in response to torque received from the drive outputs  74  of the instrument driver  75 . When designed for endoscopy, the distal end of a flexible elongated shaft may include a steerable or controllable bending section that may be articulated and bent based on torque received from the drive outputs  74  of the instrument driver  75 . 
     Torque from the instrument driver  75  is transmitted down the elongated shaft  71  using tendons within the shaft  71 . These individual tendons, such as pull wires, may be individually anchored to individual drive inputs  73  within the instrument handle  72 . From the handle  72 , the tendons are directed down one or more pull lumens within the elongated shaft  71  and anchored at the distal portion of the elongated shaft  71 . In laparoscopy, these tendons may be coupled to a distally mounted end effector, such as a wrist, grasper, or scissor. Under such an arrangement, torque exerted on drive inputs  73  would transfer tension to the tendon, thereby causing the end effector to actuate in some way. In laparoscopy, the tendon may cause a joint to rotate about an axis, thereby causing the end effector to move in one direction or another. Alternatively, the tendon may be connected to one or more jaws of a grasper at distal end of the elongated shaft  71 , where tension from the tendon cause the grasper to close. 
     In endoscopy, the tendons may be coupled to a bending or articulating section positioned along the elongated shaft  71  (e.g., at the distal end) via adhesive, control ring, or other mechanical fixation. When fixedly attached to the distal end of a bending section, torque exerted on drive inputs  73  would be transmitted down the tendons, causing the softer, bending section (sometimes referred to as the articulable section or region) to bend or articulate. Along the non-bending sections, it may be advantageous to spiral or helix the individual pull lumens that direct the individual tendons along (or inside) the walls of the endoscope shaft to balance the radial forces that result from tension in the pull wires. The angle of the spiraling and/or spacing there between may be altered or engineered for specific purposes, wherein tighter spiraling exhibits lesser shaft compression under load forces, while lower amounts of spiraling results in greater shaft compression under load forces, but also exhibits limits bending. On the other end of the spectrum, the pull lumens may be directed parallel to the longitudinal axis of the elongated shaft  71  to allow for controlled articulation in the desired bending or articulable sections. 
     In endoscopy, the elongated shaft  71  houses a number of components to assist with the robotic procedure. The shaft may comprise of a working channel for deploying surgical tools, irrigation, and/or aspiration to the operative region at the distal end of the shaft  71 . The shaft  71  may also accommodate wires and/or optical fibers to transfer signals to/from an optical assembly at the distal tip, which may include of an optical camera. The shaft  71  may also accommodate optical fibers to carry light from proximally-located light sources, such as light emitting diodes, to the distal end of the shaft. 
     At the distal end of the instrument  70 , the distal tip may also comprise the opening of a working channel for delivering tools for diagnostic and/or therapy, irrigation, and aspiration to an operative site. The distal tip may also include a port for a camera, such as a fiberscope or a digital camera, to capture images of an internal anatomical space. Relatedly, the distal tip may also include ports for light sources for illuminating the anatomical space when using the camera. 
     In the example of  FIG. 13 , the drive shaft axes, and thus the drive input axes, are orthogonal to the axis of the elongated shaft. This arrangement, however, complicates roll capabilities for the elongated shaft  71 . Rolling the elongated shaft  71  along its axis while keeping the drive inputs  73  static results in undesirable tangling of the tendons as they extend off the drive inputs  73  and enter pull lumens within the elongate shaft  71 . The resulting entanglement of such tendons may disrupt any control algorithms intended to predict movement of the flexible elongate shaft during an endoscopic procedure. 
       FIG. 14  illustrates an alternative design for an instrument driver and instrument where the axes of the drive units are parallel to the axis of the elongated shaft of the instrument. As shown, a circular instrument driver  80  comprises four drive units with their drive outputs  81  aligned in parallel at the end of a robotic arm  82 . The drive units, and their respective drive outputs  81 , are housed in a rotational assembly  83  of the instrument driver  80  that is driven by one of the drive units within the assembly  83 . In response to torque provided by the rotational drive unit, the rotational assembly  83  rotates along a circular bearing that connects the rotational assembly  83  to the non-rotational portion  84  of the instrument driver. Power and controls signals may be communicated from the non-rotational portion  84  of the instrument driver  80  to the rotational assembly  83  through electrical contacts may be maintained through rotation by a brushed slip ring connection (not shown). In other embodiments, the rotational assembly  83  may be responsive to a separate drive unit that is integrated into the non-rotatable portion  84 , and thus not in parallel to the other drive units. The rotational mechanism  83  allows the instrument driver  80  to rotate the drive units, and their respective drive outputs  81 , as a single unit around an instrument driver axis  85 . 
     Like earlier disclosed embodiments, an instrument  86  may comprise of an elongated shaft portion  88  and an instrument base  87  (shown with a transparent external skin for discussion purposes) comprising a plurality of drive inputs  89  (such as receptacles, pulleys, and spools) that are configured to receive the drive outputs  81  in the instrument driver  80 . Unlike prior disclosed embodiments, instrument shaft  88  extends from the center of instrument base  87  with an axis substantially parallel to the axes of the drive inputs  89 , rather than orthogonal as in the design of  FIG. 13 . 
     When coupled to the rotational assembly  83  of the instrument driver  80 , the medical instrument  86 , comprising instrument base  87  and instrument shaft  88 , rotates in combination with the rotational assembly  83  about the instrument driver axis  85 . Since the instrument shaft  88  is positioned at the center of instrument base  87 , the instrument shaft  88  is coaxial with instrument driver axis  85  when attached. Thus, rotation of the rotational assembly  83  causes the instrument shaft  88  to rotate about its own longitudinal axis. Moreover, as the instrument base  87  rotates with the instrument shaft  88 , any tendons connected to the drive inputs  89  in the instrument base  87  are not tangled during rotation. Accordingly, the parallelism of the axes of the drive outputs  81 , drive inputs  89 , and instrument shaft  88  allows for the shaft rotation without tangling any control tendons. 
     E. Navigation and Control. 
     Traditional endoscopy may involve the use of fluoroscopy (e.g., as may be delivered through a C-arm) and other forms of radiation-based imaging modalities to provide endoluminal guidance to an operator physician. In contrast, the robotic systems contemplated by this disclosure can provide for non-radiation-based navigational and localization means to reduce physician exposure to radiation and reduce the amount of equipment within the operating room. As used herein, the term “localization” may refer to determining and/or monitoring the position of objects in a reference coordinate system. Technologies such as pre-operative mapping, computer vision, real-time EM tracking, and robot command data may be used individually or in combination to achieve a radiation-free operating environment. In other cases, where radiation-based imaging modalities are still used, the pre-operative mapping, computer vision, real-time EM tracking, and robot command data may be used individually or in combination to improve upon the information obtained solely through radiation-based imaging modalities. 
       FIG. 15  is a block diagram illustrating a localization system  90  that estimates a location of one or more elements of the robotic system, such as the location of the instrument, in accordance to an example embodiment. The localization system  90  may be a set of one or more computer devices configured to execute one or more instructions. The computer devices may be embodied by a processor (or processors) and computer-readable memory in one or more components discussed above. By way of example and not limitation, the computer devices may be in the tower  30  shown in  FIG. 1 , the cart shown in  FIGS. 1-4 , the beds shown in  FIGS. 5-10 , etc. 
     As shown in  FIG. 15 , the localization system  90  may include a localization module  95  that processes input data  91 - 94  to generate location data  96  for the distal tip of a medical instrument. The location data  96  may be data or logic that represents a location and/or orientation of the distal end of the instrument relative to a frame of reference. The frame of reference can be a frame of reference relative to the anatomy of the patient or to a known object, such as an EM field generator (see discussion below for the EM field generator). 
     The various input data  91 - 94  are now described in greater detail. Pre-operative mapping may be accomplished through the use of the collection of low dose CT scans. Pre-operative CT scans are reconstructed into three-dimensional images, which are visualized, e.g. as “slices” of a cutaway view of the patient&#39;s internal anatomy. When analyzed in the aggregate, image-based models for anatomical cavities, spaces and structures of the patient&#39;s anatomy, such as a patient lung network, may be generated. Techniques such as center-line geometry may be determined and approximated from the CT images to develop a three-dimensional volume of the patient&#39;s anatomy, referred to as model data  91  (also referred to as “preoperative model data” when generated using only preoperative CT scans). The use of center-line geometry is discussed in U.S. patent application Ser. No. 14/523,760, the contents of which are herein incorporated in its entirety. Network topological models may also be derived from the CT-images, and are particularly appropriate for bronchoscopy. 
     In some embodiments, the instrument may be equipped with a camera to provide vision data  92 . The localization module  95  may process the vision data to enable one or more vision-based location tracking. For example, the preoperative model data may be used in conjunction with the vision data  92  to enable computer vision-based tracking of the medical instrument (e.g., an endoscope or an instrument advance through a working channel of the endoscope). For example, using the preoperative model data  91 , the robotic system may generate a library of expected endoscopic images from the model based on the expected path of travel of the endoscope, each image linked to a location within the model. Intra-operatively, this library may be referenced by the robotic system in order to compare real-time images captured at the camera (e.g., a camera at a distal end of the endoscope) to those in the image library to assist localization. 
     Other computer vision-based tracking techniques use feature tracking to determine motion of the camera, and thus the endoscope. Some feature of the localization module  95  may identify circular geometries in the preoperative model data  91  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 camera. Use of a topological map may further enhance vision-based algorithms or techniques. 
     Optical flow, another computer vision-based technique, may analyze the displacement and translation of image pixels in a video sequence in the vision data  92  to infer camera movement. Examples of optical flow techniques may include motion detection, object segmentation calculations, luminance, motion compensated encoding, stereo disparity measurement, etc. Through the comparison of multiple frames over multiple iterations, movement and location of the camera (and thus the endoscope) may be determined. 
     The localization module  95  may use real-time EM tracking to generate a real-time location of the endoscope in a global coordinate system that may be registered to the patient&#39;s anatomy, represented by the preoperative model. In EM tracking, an EM sensor (or tracker) comprising of one or more sensor coils embedded in one or more locations and orientations in a medical instrument (e.g., an endoscopic tool) measures the variation in the EM field created by one or more static EM field generators positioned at a known location. The location information detected by the EM sensors is stored as EM data  93 . The EM field generator (or transmitter), may be placed close to the patient to create a low intensity magnetic field that the embedded sensor may detect. The magnetic field induces small currents in the sensor coils of the EM sensor, which may be analyzed to determine the distance and angle between the EM sensor and the EM field generator. These distances and orientations may be intra-operatively “registered” to the patient anatomy (e.g., the preoperative model) in order to determine the geometric transformation that aligns a single location in the coordinate system with a position in the pre-operative model of the patient&#39;s anatomy. Once registered, an embedded EM tracker in one or more positions of the medical instrument (e.g., the distal tip of an endoscope) may provide real-time indications of the progression of the medical instrument through the patient&#39;s anatomy. 
     Robotic command and kinematics data  94  may also be used by the localization module  95  to provide localization data  96  for the robotic system. Device pitch and yaw resulting from articulation commands may be determined during pre-operative calibration. Intra-operatively, these calibration measurements may be used in combination with known insertion depth information to estimate the position of the instrument. Alternatively, these calculations may be analyzed in combination with EM, vision, and/or topological modeling to estimate the position of the medical instrument within the network. 
     As  FIG. 15  shows, a number of other input data can be used by the localization module  95 . For example, although not shown in  FIG. 15 , an instrument utilizing shape-sensing fiber can provide shape data that the localization module  95  can use to determine the location and shape of the instrument. 
     The localization module  95  may use the input data  91 - 94  in combination(s). In some cases, such a combination may use a probabilistic approach where the localization module  95  assigns a confidence weight to the location determined from each of the input data  91 - 94 . Thus, where the EM data may not be reliable (as may be the case where there is EM interference) the confidence of the location determined by the EM data  93  can be decrease and the localization module  95  may rely more heavily on the vision data  92  and/or the robotic command and kinematics data  94 . 
     As discussed above, the robotic systems discussed herein may be designed to incorporate a combination of one or more of the technologies above. The robotic system&#39;s computer-based control system, based in the tower, bed and/or cart, may store computer program instructions, for example, within a non-transitory computer-readable storage medium such as a persistent magnetic storage drive, solid state drive, or the like, that, upon execution, cause the system to receive and analyze sensor data and user commands, generate control signals throughout the system, and display the navigational and localization data, such as the position of the instrument within the global coordinate system, anatomical map, etc. 
     2. Directed Fluidics 
     Embodiments of the disclosure relate to systems and techniques for removing an object from a treatment site of a patient, and in particular to methods and systems that employ directed fluidics during an object removal procedure. 
     During object removal procedures, fluidics (e.g., irrigation (inflow) and/or aspiration (outflow) of a liquid, such as saline) may be applied to the treatment site. During percutaneous nephrolithotomy (PCNL), for example, fluidics can be used to clear the visual field of stone dust and small fragments caused by the breakup of the kidney stone. As discussed in greater detail below, however, the conventional approach to fluidics during object removal procedures can also cause complications. For example, irrigation may create currents within the treatment site that move the object to be removed away from the medical instruments used during the procedure. 
     As used herein, the term “directed fluidics” applies to the methods, techniques, and systems described in this disclosure that improve on conventional fluidics, facilitate object removal procedures, and/or resolve or alleviate one or more problems associated with conventional object removal procedures. In general, directed fluidics involves controlling various features of the flow (e.g., rate, direction, pressure, position, etc.) of irrigation and/or aspiration, and/or separating an inflow point (or points) of irrigation from an outflow point (or points) of aspiration to facilitate an object removal procedure. In some examples, directed fluidics involves providing irrigation and aspiration through a single medical instrument (e.g. a percutaneously inserted medical instrument), and may also involve controlling features of the irrigation and aspiration to facilitate object removal. In some examples, directed fluidics involves controlling a flow direction from an inflow point to an outflow point so as to, for example, hold or stabilize an object during the procedure. These and other features of directed fluidics, as well as various methods and systems for implementing directed fluidics during an object removal procedure, will become apparent from the following detailed description of several examples. The following examples are intended to illustrate the principles of this disclosure and should not be construed as limiting the disclosure. 
     In several of the examples described herein, the object removal procedure relates to removal of kidney stones from a kidney. This disclosure, however, is not limited only to kidney stone removal. For example, the following description is also applicable to other surgical or medical operations or medical procedures concerned with the removal of objects from a patient, including any object that can be removed from a treatment site or patient cavity (e.g., the esophagus, ureter, intestine, eye, etc.) via percutaneous and/or endoscopic access, such as, for example, gallbladder stone removal, lung (pulmonary/transthoracic) tumor biopsy, or cataract removal. 
     A. Background Discussion of Object Removal. 
     As mentioned above, object removal is a common surgical operation or medical procedure. To better understand the features and advantages of the methods and systems for object removal that employ directed fluidics as described herein, this section first presents background information related to certain object removal procedures. By way of example, procedures for removing a kidney stone from a kidney are described. 
     Generally, there are several methods for treating patients with kidney stones, including observation, medical treatments (such as expulsion therapy), non-invasive treatments (such as extracorporeal shock wave lithotripsy (ESWL), and surgical treatments (such as ureteroscopy and PCNL). In the two surgical approaches (ureteroscopy and PCNL), the physician gains access to the pathology (i.e., the object to be removed; e.g., the stone), energy is delivered to the stone to break it into smaller pieces or fragments, and the small stone fragments/particulates are mechanically extracted from the kidney. 
     A component of PCNL is the use of fluidics (irrigation and aspiration). During PCNL, fluidics are applied to clear stone dust, small fragments, and thrombus from the treatment site as well as the visual field provided by the medical instruments. 
       FIG. 16  illustrates an example procedure for removing an object  101  from a kidney  103  using a medical instrument  100  inserted into the kidney  103  percutaneously. The illustrated example may be representative of a PCNL procedure. The object  101  can be any object that is targeted for removal, such as a kidney stone. In the illustrated example, the medical instrument  100  comprises a laparoscope or nephroscope  105 . The nephroscope  105  can be inserted percutaneously into the kidney  103  through an access sheath  107 . The nephroscope  105  can include a working channel  108 , though which various tools can be inserted. As illustrated, a lithotripter  109  (such as an ultrasonic lithotripter) can be inserted through the working channel  108  of the nephroscope  105 . The nephroscope  105  can also include an optic configured to allow a surgeon to visualize the treatment site. A field of view  117  of the optic is illustrated. 
     In general, the medical instrument  100  is navigated within the kidney  103  by torqueing the medical instrument  100  towards the object  101 . The surgeon&#39;s goal is to touch the distal end  121  of the lithotripter  109  to the object  101  to break the object  101  into smaller fragments that can then be removed. 
     As illustrated with arrows in  FIG. 16 , irrigation (for example, of a saline solution) can be applied to the treatment site (e.g., the kidney  103 ) through the medical instrument  100 . In this example, irrigation passes through the nephroscope  105 , exiting through a distal tip  113  into the kidney  103 . Irrigation can be used to clear stone dust and small fragments from the field of view  117  to allow the surgeon to visualize the treatment site, as well as to distend the kidney  103  to allow access to the object  101 . In the illustrated example, aspiration is also applied to the treatment site through the medical instrument  100 . As shown, liquid can be removed from the kidney  103  through the access sheath  107  as well as through a channel in the lithotripter  109 . In some instances, irrigation is pumped (actively) through the lithotripter  109 , while the remainder of the irrigation through the access sheath  107  is passive (e.g., passively flowing through the access sheath  107 ). In some examples, fluidics are applied during the entire procedure. 
     The fluidics applied during the procedure can establish a fluid flow as illustrated by the arrows in  FIG. 16 . Initially, fluid can flow outward from the distal tip  113  of the nephroscope  105  towards the object  101 . Irrigation through the access sheath  107  and lithotripter  109  can cause fluid flow back towards the medical instrument  100 . As illustrated, in the region of the object  101 , the flow is both directed toward and away from the object  101  with respect to the distal end of the medical instrument  100 . In some instances, the net effect of such a flow may be that many small and unpredictable eddies  119  are formed around the object  101  and the distal end of the medical instrument  100 . This may result in the object  101  being pushed away from the medical instrument  100 . This can prevent the surgeon from contacting the lithotripter  109  to the object  101  and/or scatter the fragments created by the lithotripter  109  as the stone is broken up. These difficulties may arise when only irrigation is actively managed, while aspiration is passive, thus not allowing for a high degree of fluidic control during the procedure. Another potential danger is that the kidney  103  may become overfilled. 
     As another example, during a ureteroscopic lithotripsy, a ureteroscope may enter the kidney through the ureter and use stone-retrieval baskets and lithotripters to relocate and break down kidney stones, respectively. For example, a lithotripter can be deployed through the ureteroscope and used to break the stone into fragments. During the lithotripsy of the kidney stones, several problems can occur. For example, the lithotripter (which applies energy to break up the stone) can cause the stone to move around unpredictably within the kidney. Further, as described above, lithotripsy generates stone dust, which can obstruct vision within the treatment site. After the stone has been broken down, the lithotripter can be removed and a basketing device can be deployed through the ureteroscope to retrieve the stone fragments. This process can be both tedious and time consuming. After attempting to remove all stone fragments by basketing, there may be small stone debris that remain. 
     The procedures for kidney stone removal discussed above (PCNL and ureteroscopy) may exhibit certain challenges or complications. For example, PCNL may use fluidics that create currents within the kidney that can move the object and fragments away from medical instrument, complicating the removal process. Ureteroscopy may use a lithotripter employed through a ureteroscope to break up the kidney stone; however, there may be no mechanism in place to stabilize the stone during lithotripsy. Often, the energy used to break up the stone causes the stone to bounce away from the lithotripter, complicating removal. Further, as the stone is broken down via lithotripsy, stone dust is generated which obstructs vision of the treatment site. Another challenge with these procedures is that it may be difficult for the physician to gain access to the treatment site because of the surrounding anatomy outside of the kidney. For example, locations for percutaneous access to the kidney may be limited due to the surrounding anatomy outside of the kidney. 
     B. Overview of Object Removal with Directed Fluidics. 
     The methods and systems described herein may be used to alleviate or resolve one or more of the problems of PCNL and ureteroscopy (described above) through the use of directed fluidics. In some embodiments, directed fluidics can be applied such that irrigation (inflow) enters the treatment site through a first channel of a first medical device (e.g., a percutaneously inserted medical instrument) and aspiration (outflow) exits the treatment site through a second channel of the first medical instrument. In some embodiments, irrigation and aspiration can both be active. In some embodiments, irrigation and aspiration can be managed to produce desirable flow characteristics. In some embodiments, a second medical instrument that does not provide irrigation or aspiration can also be used during the procedure, for example, to break up the object being removed. In some embodiments, directed fluidics can be applied such that irrigation (inflow) enters the treatment site through a first medical device (e.g., a catheter or endoscope), while aspiration (outflow) exits the treatment site through a second medical instrument (e.g., a catheter or endoscope). This can create a controlled flow from the first instrument towards the second instrument. The controlled flow can facilitate object removal. The first medical instrument can be inserted into the treatment site antegrade of the object to be removed, while the second medical instrument can be inserted into the treatment site retrograde of the object. The first medical instrument can be inserted through a patient lumen or percutaneously. The second medical instrument can be inserted through a patient lumen or percutaneously. In some embodiments, the first medical instrument is inserted into the treatment site (e.g., the kidney) through a patient lumen (e.g., the ureter) and the second medical instrument is inserted into the treatment site percutaneously, or vice versa. 
     One or both of the first and second medical instruments can be robotically controlled medical instruments as described above with reference to  FIGS. 1-15 . Accordingly, the methods and systems described below can be employed robotically in some embodiments. 
     In some instances, directed fluidics can include the separation of the point(s) of inflow (irrigation) from the point(s) of outflow (aspiration). The inflow can be directed towards the point of outflow, for example by deflecting the distal end of a first medical instrument towards a second medical instrument such that the fluid flow is towards the second medical instrument. This may be accomplished robotically and/or automatically with the systems and instruments described above with reference to  FIGS. 1-15 . In some embodiments, the point of inflow (irrigation) does not need to be directional (i.e., pointed in a specific direction), provided that the first medical instrument is configured to achieve a sufficiently high inflow rate without causing turbulence. This may allow the treatment site (e.g., the kidney) to fill up with fluid without displacing the stone. In some embodiments, the point of outflow (aspiration) may be a single or concentrated point. The point of outflow may be configured to provide high flow with high velocities so as to cause fragments to be pulled towards the point of outflow. 
     In some embodiments, the irrigation and aspiration rates can be modulated to improve stone displacement or stabilization or to intentionally create turbulence so that the irrigation reaches all corners of the treatment site. For example, a gentle alternating cycle of irrigation and aspiration can create a lavage like effect to preferentially pull large stone debris away from calyces and towards the aspiration site. Alternatively, short pulsatile inflow and outflow could be used to create turbulence and ensure that smaller and lighter stone fragments do not settle on the floor of the treatment site, but instead remain floating in the irrigant and eventually get aspirated with the outflow. 
       FIG. 17  illustrates an example procedure for removing an object  101  from a kidney  103  using a first medical instrument  200  inserted into the kidney  103  through a patient lumen  202 , a second medical instrument  204  inserted into the kidney percutaneously, and directed fluidics. In the illustrated example of  FIG. 17 , the first medical instrument  200  comprises an endoscope, such as a ureteroscope. The patient lumen  202  can comprise the ureter. The first medical instrument  200  can include a channel for supplying irrigation. The channel can be connected to an irrigation source and a pump (see  FIG. 25 ). The first medical instrument  200  may be articulable. The first medical instrument  200  may be robotically controlled. 
     As illustrated, the second medical instrument  204  can include a nephroscope  105 . The nephroscope  105  can be a rigid nephroscope. The nephroscope  105  can be inserted percutaneously into the kidney  103  through an access sheath  107 . The nephroscope  105  can include a working channel  108 , though which various tools can be inserted or that may be used as channels for aspiration or irrigation. In some embodiments, other channels within the nephroscope can be used for aspiration and irrigation. As illustrated, a lithotripter  109  (such as an ultrasonic lithotripter) may be inserted through the working channel  108  of the nephroscope  105 . The nephroscope  105  can also include an optic configured to allow a surgeon to visualize the treatment site. A field of view  117  of the optic is illustrated. 
     Fluid flow is illustrated with arrows in  FIG. 17 . As shown, irrigation is provided through the first medical instrument  200  and aspiration is provided through the second medical instrument  204 . In the illustrated embodiment, irrigation is provided through the lithotripter  109 , but irrigation could be provided alternatively (or additionally) through the nephroscope  105  and/or access sheath  107 . As shown, the points of inflow (irrigation) and outflow (aspiration) are separated and a general flow direction is established from the first medical instrument  200  to the second medical instrument  204 . 
     As mentioned above, the second medical instrument  204  may include an optic (e.g., a camera) for visualizing the treatment site (with field of view  117 ). Because flow is directed continuously away from the first instrument  200  and towards the second instrument  204 , the field of view  117  of the optic can remain clear, allowing improved visualization of the treatment site. Further, because flow is directed towards the second medical instrument  204 , which includes the lithotripter  109 , the object  101  and fragments can be pushed towards the second medical instrument  204 , beneficially facilitating contact with the lithotripter  109 . 
     This concept of directed fluidics allows debris, dust, thrombus, and fragments to naturally flow towards the second medical instrument  204  and into the stone extraction or destruction device (lithotripter  109 ). In the event that the physician is required to pursue fragments, he or she may need to maneuver the devices to a lesser extent than during other procedures owed to the tendency of fragments to flow toward rather than away from the second medical device  204 . 
     Additionally, in the event that irrigation is provided through the nephroscope  105  and/or access sheath  107 , this may enable the use of a much larger diameter lithotripter  109  because the irrigation and/or aspiration no longer need to be provided through the lithotripter  109 . 
     In another example, the second instrument  204  can be an articulable catheter that is introduced via percutaneous access into the treatment site (e.g., the kidney) (see  FIGS. 18, 19, 26A, and 26B ). The catheter can be configured to be able to navigate within the kidney. For example, the catheter may be configured to be inserted and retracted into the treatment site and/or to articulate (e.g., bend). In some embodiments, the catheter can include pull-wires for controlling articulation. In some embodiments, four pull-wires are oriented in the four orthogonal directions to enable articulation of the catheter. Other methods for permitting articulation of the catheter are also possible. The catheter can include, for example, an aspiration lumen (or channel). The aspiration lumen can be connected to a pump. The pump may be an external pump. The pump may generate negative pressure that causes flow from the treatment site into the catheter. The aspiration function may be able to be toggled (e.g., on and off) and adjusted by the user or system. In some embodiments, the aspiration lumen may be used for irrigation. 
     The catheter can provide several functions during an object removal procedure employing directed fluidics. For example, the catheter can stabilize the stone during lithotripsy. If the stone is larger than the aspiration lumen of the catheter, the stone can be held at the distal face of the aspiration lumen, thus stabilizing the stone while it is broken down to dust and smaller fragments. The aspiration flow may hold the stone to the distal face. This may provide the user with a less mobile target for lithotripsy. 
     The catheter can improve visibility of the treatment site. The catheter can remove stone dust from the kidney. This can provide the user with improved visibility (e.g., continuously adequate visibility), for example, from an imaging device inserted into the treatment site (for example, on a medical instrument inserted into the treatment site). 
     The catheter can remove stone dust and fragments. The fluid flow can carry fluid and debris into the catheter. The debris may be cleared as it is generated (i.e., while the stone is being broken up). The removal of debris via the catheter can take the place of removal of fragments via ureteroscopic basketing, which can be time consuming due to the difficulty of closing the basket around the stone, and due to the need to remove and re-insert the ureteroscope during each fragment removal. This can result in a more efficient removal procedure. Such a procedure may be completed faster because, for example, fragments are removed as the stone is broken up. Removing stone debris via the catheter can also reduce the risk of the stone fragment injuring tissue (such as during removal of stone through the ureter). 
     The catheter can be used to relocate kidney stones. For example, the catheter can be configured to navigate within the kidney towards stone or stone debris. With aspiration, the stone or stone debris can be held onto the distal tip of the catheter, and moved to another location within the kidney. This function may remove or reduce the need to use a basket device to relocate or move the stone. The catheter can also be configured to be advanced into the ureter to retrieve stones or fragments that have migrated into the ureter. This may allow a physician to perform the procedure without ureteral protection devices that are sometimes employed during certain procedures. 
     The catheter can be used in several ways during a procedure. For example, the catheter can be mobile throughout the procedure. The catheter can navigate around the treatment site to target specific stones/fragments in order to constrain them during lithotripsy, while also aspirating dust/debris. As another example, the catheter can be initially stationary during the procedure and the first medical instrument (e.g., a ureteroscope) could be used to relocate stones to the catheter. The stones could be broken down at the catheter. At a later time during the procedure, the catheter could navigate through the treatment site to pick up remaining debris. As another example, the catheter could be inserted (e.g., percutaneously) only when required, for example, during procedure escalation. 
       FIG. 18  illustrates an example procedure for removing an object  101  from a kidney  103  using a first medical instrument  200  inserted into the kidney  103  through a patient lumen  202 , a second medical instrument  204 , such as a steerable catheter, inserted into the kidney  103  percutaneously (for example, through an access sheath  107 ), and directed fluidics. Irrigation may be provided through the first medical instrument  200  and aspiration may be provided through the second medical instrument  204 . In this example, the points of inflow (irrigation) and outflow (aspiration) are separated and a general flow direction is established from the first medical instrument  200  towards the second medical instrument  204 . Arrows illustrate the direction of fluid flow. 
     As illustrated in  FIG. 18 , the first medical instrument  200  can be articulable. That is the shape or pose of the first medical instrument  200  can be controlled. In some embodiments, the articulation is controlled robotically as described above. As illustrated, the first medical instrument  200  can be articulated such that the irrigation flow is oriented or directed towards the second medical instrument  204 . This may help establish the fluid flow from the first medical instrument  200  towards the second medical instrument  204 . 
     The second medical instrument  204  (e.g., the steerable catheter) can also be articulable. That is the shape or pose of the second medical instrument  204  can be controlled. In some embodiments, the articulation is controlled robotically as described above. As illustrated, the second medical instrument  204  can include an articulable distal tip  206 . The second medical instrument  204  (or the distal tip  206  thereof) can be articulated such that that the distal tip  206  is oriented or directed towards the first medical instrument  200  and/or the object  101 . This may help establish the fluid flow from the first medical instrument  200  towards the second medical instrument  204 , thereby serving to pull the object  101  towards the second medical instrument  204 . 
       FIG. 19  illustrates another example procedure for removing an object  101  from a kidney  103  using a first medical instrument  200  inserted into the kidney  103  through a patient lumen  202 , a second medical instrument  204  (such as a steerable catheter) inserted into the kidney  103  percutaneously (for example, through an access sheath  107 ), and directed fluidics. In the illustrated example, the first medical instrument  200  includes a lithotripter  109 . Fluid flow from the first medical instrument  200  to the second medical instrument  204  can be used to hold the object  101  and/or fragments onto the distal tip  206  of the second medical instrument  204 . This can stabilize the object  101  and/or fragments during lithotripsy with the lithotripter  109  of first medical instrument  200 . The distal tip  206  of the second medical instrument  204  can include a pocket (or other holding device) on its distal tip to stabilize and hold the object  101  and/or fragments. See, for example,  FIGS. 26A and 26B  described below. 
       FIG. 20  provides a detailed view of a distal tip  203  of the first medical instrument  200  (providing irrigation) and a distal tip  206  of the second medical  204  instrument (providing aspiration during) an object removal procedure. Arrows illustrate the direction of flow from the first medical instrument  200  to the second medical instrument  204 . As shown, irrigation passes through a first fluid channel  205  in the first medical instrument  200  and exits at a distal tip  203 . Aspiration is provided through the distal tip  206  and second fluid channel  207 . As shown, the flow directs the object  101  towards the distal tip  206  of the second medical instrument  204 . 
     In some examples, the catheter can also have the ability to provide irrigation of fluid into the kidney (in addition to the aspiration described above). For example, an irrigation channel of the catheter can start at the proximal end of the catheter and can include the annular space between the catheter shaft and the aspiration lumen tubing. The distal end of the catheter can include irrigation openings. For example, the catheter can include circumferential holes (e.g. four holes) from which the irrigation fluid exits. The irrigation may be toggled on/off by the user or system. The irrigation may be connected to a fluidics system that has the ability to balance or otherwise modify the irrigation/aspiration levels as described herein. 
       FIG. 21A  provides a detailed view of a distal tip of a first medical instrument  200  providing irrigation and a distal tip  206  of a second medical instrument  204  providing both irrigation and aspiration during an object removal procedure (see also  FIGS. 26A and 26B  described below). Arrows illustrate the direction of flow from the first medical instrument  200  to the second medical instrument  204 . As shown, in this example, irrigation passes through a first fluid channel  205  in the first medical instrument  200  and exits at a distal tip  203 . Similar to  FIG. 20 , aspiration is provided through the distal tip  206  and second fluid channel  207  of the second medical instrument  204 . However, the second medical instrument  204  also includes additional fluid channels  209  for supplying irrigation. The additional fluid channels  209  can annularly surround the second fluid channel  207 . In the illustrated embodiments, the additional fluid channels  209  terminate at fluid outlets  211  near the distal tip  206  of the second medical instrument  204 . In some embodiments, the fluid outlets  211  can direct the irrigation from the second medical instrument  204  away from the distal tip  206 . In some embodiments, the fluid outlets  211  can direct the irrigation radially away from the distal tip  206 . As shown, the flow can direct the object  101  towards the distal tip  206  of the second medical instrument  204 . 
     In some implementations, irrigation and aspiration can be provided through a single medical instrument, while another medical instrument may be used for performing additional aspects of the procedure. For example,  FIG. 21B  provides a detailed view of a distal tip of a first medical instrument  200  performing lithotomy with a lithotripter  216  and a distal tip  206  of a second medical instrument  204  providing both irrigation and aspiration during an object removal procedure. The second medical instrument  204  may be similar to the instrument  700  described below with reference to  FIGS. 26A and 26B . As shown, in this example, only the second instrument  204  is used to provide fluidics. Both irrigation and aspiration are provided through the second instrument  204 . 
     Directed fluidics can provide one or more of the following advantages. During a ureteroscopic lithotripsy, the kidney stone can move around and migrate within the kidney. The energy from the lithotripter may exacerbate this movement. Directed fluidics, with or without a catheter that provides both aspiration and irrigation, can use aspiration to constrain these unwanted stone movements. For example, the fluid flow can hold the stone to the distal end of the instrument. 
     Additionally, during lithotripsy, small dust particles form, which can obscure vision through the ureteroscope. In some ureteroscopic lithotripsy, the vision can become so obscured that the procedure must be stopped. Directed fluidics, with or without a catheter that provides both aspiration and irrigation, can provide the advantage of aspirating the dust particles (or other matter) out of the treatment site, providing the user with continuous good visibility. 
     Additionally, basketing can be time consuming due to the difficulty of capturing stone fragments within a basket and then removing the entire ureteroscope from the patient for each fragment removal. Directed fluidics can provide the advantage of quick removal of stone fragments as they are formed. 
     Finally, during some ureteroscopic lithotripsy, if a kidney stone needs to be relocated, a basket retrieval device is often used, which may be time consuming due to the need to position the stone in the basket, and due to the need to exchange the lithotripter for the basket retrieval device. Directed fluidics can provide the advantage of navigating the catheter through the kidney and using aspiration to hold onto the stone, and then relocating the stone to another location in the kidney by moving the aspiration catheter. 
     C. Example Methods for Directed Fluidics. 
       FIG. 22A  is a flowchart illustrating an embodiment of a method  300  for administering directed fluidics during a medical procedure, such as an object removal procedure. In some examples, the object removal procedure is a procedure for removing a kidney stone from a kidney. The method  300  can be also be implemented in other types of medical procedures and in other treatment sites. In some embodiments, the method  300  is implemented in a robotic medical system, for example, any of the systems described above with reference to  FIGS. 1-15 . 
     The method  300  begins at block  302 . At block  302 , a first medical instrument is inserted into a treatment site. The first medical instrument can be inserted through a lumen of the patient. In the example of kidney stone removal, the patient lumen may be the ureter. In some examples, the first medical instrument can be inserted percutaneously into the treatment site. The first medical instrument can be an endoscope, nephroscope, catheter, or other type of medical instrument. The first medical instrument can be articulable. In some examples, the first medical instrument is not articulable. In some embodiments, the first medical instrument can include one or more working channels configured to receive various tools (e.g., lithotripters, basket retrieval devices, forceps, etc.) therethrough. The first medical instrument can include at least one first fluid channel. The first fluid channel can be configured to provide fluidics to the treatment site during the medical procedure. 
     At block  304 , a second medical instrument is inserted into the treatment site. The second medical instrument can be inserted through a lumen of the patient. In the example of kidney stone removal, the patient lumen may be the ureter. In some examples, the second medical instrument can be inserted percutaneously into the treatment site. The second medical instrument can be an endoscope, nephroscope, catheter, or other type of medical instrument. The second medical instrument can be articulable. In some examples, the second medical instrument is not articulable. The second medical instrument can include one or more working channels configured to receive various tools (e.g., lithotripters, basket retrieval devices, forceps, etc.) therethrough. The second medical instrument can include at least one second fluid channel. The second fluid channel can be configured to provide fluidics to the treatment site during the medical procedure. 
     In some instances, the order of block  302  and block  304  can be reversed. In some instances, block  302  and block  304  can be performed at the same time. 
     In some instances, the first and second medical devices are inserted into the treatment site via different methods of access. For example, the first medical instrument may be inserted through a patient lumen and the second medical instrument may be inserted percutaneously, or vice versa. As another example, the first medical instrument can be inserted into the treatment site through a first patient lumen, and the second medical instrument can be inserted into the treatment side through a second patient lumen different than the first patient lumen. As another example, the first medical device can be inserted through a first percutaneous access, and the second medical device can be inserted through a second percutaneous access different than the first percutaneous access. In some examples, the first and second medical devices are inserted through the same patient lumen or through the same percutaneous access. 
     In some instances, the first and second medical devices are inserted into the treatment site such that the distal ends of the first and second medical devices are separated within the treatment site. For example, the distal end of the first medical device can be positioned antegrade of the object to be removed, and the distal end of the second medical device can be positioned retrograde of the object to be removed. As another example, the distal end of the medical device can be positioned retrograde of the object to be removed, and the distal end of the second medical device can be positioned antegrade of the object to be removed. In some instances, the first and second medical devices are positioned such that the object is positioned between the distal ends of the first and second medical devices. 
     In some instances, the distal end of the first medical device can be oriented (e.g., directed or pointed) towards the distal end of the second medical device. Alternatively or additionally, the distal end of the second medical device can be oriented towards the distal end of first medical device. In some examples, “pointing towards” can refer to a general axis or direction of fluid flow entering or exiting the first or second fluid channel of the first or second medical instrument. In some embodiments, the distal ends of the first and second medical devices can include position sensors. The position sensors can be EM sensors. The EM sensors can be configured to provide position information regarding the distal ends of the first and second medical devices and/or orientation information regarding the distal ends of the first and second medical devices. Other types of position and orientation sensors can be used. An output of the position sensors may be used to orient that first and second medical instruments. In some embodiments, the first and second medical instruments can be oriented visually or through other methods. 
     In some instances, the distal end of the first medical instrument can be brought into contact with the object to be removed. Alternatively or additionally, the distal end of the second medical instrument can be brought into contact with the object to be removed. In some embodiments, neither instrument contacts the object to be removed. 
     At block  306 , irrigation is provided through the first medical instrument. For example, irrigation can be provided through the first fluid channel of the first medical instrument. The first fluid channel can be connected to an irrigation source through a pump. The irrigation source can provide a fluid irrigant (such as saline) for irrigating the treatment site. The pump can be configured to move the irrigant through the fluid channel and into the treatment site. In one example, the pump is a peristaltic pump. The pump can be configured to set a specific flowrate through the first medical instrument. In another example, the pump can be a vacuum source configured to apply a negative pressure that draws the irrigant from the irrigation source, out through the first medical instrument, and into the treatment site. Flow rate can be varied by adjusting the vacuum pressure. 
     At block  308 , aspiration is provided through the second medical instrument. For example, aspiration can be provided through the second fluid channel of the second medical instrument. The second fluid channel can be connected to a collection container through a vacuum. The vacuum can be configured to apply a negative pressure that draws the fluid (e.g., the irrigant) from the treatment site, through the second medical instrument, and into the collection container. Flow rate can be varied by adjusting the vacuum pressure. In another example, the vacuum can be replaced with a pump, such as peristaltic pump. The pump can be used to move fluid (e.g., the irrigant) from the treatment site, through the second medical instrument, and into the collection container. The pump or vacuum can be configured to set a specific flowrate through the second medical instrument. 
     In some instances, the order of blocks  306  and block  308  can be reversed. In some instances, block  306  and block  308  can be performed at the same time. In some instances, block  306  and block  308  can be performed alternatingly, such that irrigation is provided, followed by aspiration, in a series of repetitive steps, for example. 
     At block  310 , the method  300  determines a characteristic of either the irrigation or the aspiration. The characteristic can be an instantaneous flow rate of the irrigation or aspiration. The characteristic can be an average flow rate of the irrigation or aspiration over a time interval. The time interval can be, for example, 1.0 seconds, 2.5, second, 5 second, 10 second, 15 seconds or longer, as well as intervals above and below the listed values. The characteristic can be a volume of fluid irrigated or aspirated during a time interval, such as, for example, any of the time intervals listed above. The characteristic can be an instantaneous fluid pressure associated with the irrigation or aspiration. The characteristic can be an average fluid pressure associated with the irrigation or aspiration over a time interval, such as, for example, any of the time intervals listed above. The fluid pressure can be, for example, a fluid pressure within the first fluid channel, a fluid pressure within the second fluid channel, or a fluid pressure within the treatment site itself. 
     In some instances, the characteristic is determined using one or more sensors. The sensor can be positioned, for example, in the first fluid channel, on the first medical instrument, in the second fluid channel, on the second medical instrument, or otherwise within in the treatment site. The sensor can be a flow rate sensor, a pressure sensor, or other sensor for determining a characteristic of the irrigation or aspiration. In some embodiments, the sensor can measure intrarenal pressure. In some instances, the characteristic is determined from the pump or vacuum source supplying the irrigation or aspiration. For example, the characteristic can be determined based on a flow rate set by the pump or a vacuum pressure applied by the vacuum source. In some instances, the characteristic is calculated from one or more known or measured parameters. For example, the characteristic can comprise a volume of irrigant within the treatment site calculated based on the amount of irrigant pumped into the treatment site. 
     At block  312 , the method  300  selects (e.g., sets or adjusts) a characteristic of the other of the irrigation or aspiration based on the characteristic of the irrigation or aspiration determined at block  310 . For example, if a characteristic of aspiration of is determined at block  310 , a characteristic of irrigation is selected at block  312  based on the determined characteristic. If a characteristic of irrigation of is determined at block  310 , a characteristic of aspiration is selected at block  312  based on the determined characteristic. 
     The selected characteristic may be any of the characteristics described above with reference to the determined characteristic of block  310 . For example, the selected characteristic can be instantaneous or average flow rate, fluid volume, pressure, etc. 
     In some instances, the selected characteristic may correspond with the determined characteristic. For example, if instantaneous flow rate of the irrigation is determined, flow rate of the aspiration is selected. This need not be the case in all instances. For example, a volume of irrigation can be determined and an instantaneous flow rate or pressure associated with aspiration can be adjusted. In some instances, the selected characteristic is selected to match the determined characteristic. For example, if a flow rate of x mL/sec of irrigation is determined, the flow rate of aspiration can be selected to match that is the flow rate of aspiration can be selected to be x mL/sec, such that the flow rates of irrigation and aspiration match. This need not be the case in all embodiments. For example, if a flow rate of x mL/sec of irrigation is determined, the flow rate of aspiration can be selected based on the determined flow rate, without exactly matching—that is the flow rate of aspiration can be selected to be y mL/sec, such that the flow rates of irrigation and aspiration do not exactly match. In some embodiments, the determined and selected characteristics are related but do not exactly match. For example, the flow rate of aspiration can be greater than, less than, or equal to the flow rate of irrigation. 
     With blocks  310  and  312 , one of aspiration and irrigation can be adjusted based on the other of aspiration or irrigation. The method  300  thus provides a way for balancing (e.g., instantaneously or over a period of time) aspiration and irrigation. The method  300  also provides a mechanism for regulating a condition of the treatment site. For example, by balancing irrigation and aspiration, an internal fluid volume or pressure of the treatment site can be adjusted or maintained. The method  300  also provides a mechanism for regulating a condition of the fluid flow. For example, by balancing irrigation and aspiration, flow rate between the first medical instrument and the second medical instrument can be adjusted or maintained. Other fluid flow characteristics can be adjusted or generated with the method  300  by, for example, pulsing the aspiration and/or irrigation. 
     Because fluid flow through the treatment site created by the method  300  is generally from the first medical instrument towards the second medical instrument, the method  300  is capable of achieving many of the advantages and benefits of directed fluidics previously described. For example, the method  300  can be used to keep a field of view clear, draw the stone (or fragments thereof) towards the second medical instrument for aspiration, hold the stone (or fragments thereof) in place during lithotripsy, and/or permit movement or relocation of the stone (or fragments thereof) by holding the stone to the distal end of the second medical instrument. 
     The method  300  can include additional steps or blocks not illustrated in  FIG. 22A . For example, the method  300  can include determining a characteristic of the treatment site. The characteristic of the treatment site can be, for example, a volume of fluid within the treatment site or a pressure within the treatment site. The determined characteristic of the treatment site can be determined with a sensor or can be calculated based on one or more characteristics of the irrigation and/or aspiration. In some embodiments, the determined characteristic of the treatment site is internal pressure of the treatment site, which can be determined based on irrigation and aspiration pressure and/or irrigation and aspiration flow rate. 
     In some instances, the determined characteristic of the treatment site can be compared to a threshold value. Upon determination that the determined characteristic meets or exceeds the threshold value, the method can include at least one of reducing irrigation into the treatment site, increasing aspiration from the treatment site, and providing an alert. For example, if the internal pressure of the treatment site is determined to be too high, the irrigation can be decreased and/or the aspiration can be increased in order to lower the pressure within the treatment site. An alarm can also be provided to the physician. 
     The method  300  may also include the step of moving a distal tip of the first medical instrument and/or the second medical instrument in a sweeping motion while providing irrigation or aspiration. That is, distal tip of the first medical instrument and/or the second medical instrument can be moved in a dithering motion. 
     The method  300  can also include performing lithotripsy on an object within the treatment site to break the object into fragments. Lithotripsy can be performed with a lithotripter inserted through the first or second medical instruments. The method  300  can also include aspirating the fragments of the object through the second fluid channel of the second medical instrument. In some instances, the second medical instrument is navigated around the treatment site to collect the fragments. In some instances, the fluid flow from the first medical instrument towards the second medical instruments carries the fragments to the second medical instrument for aspiration. 
     As noted previously, the second medical instrument can be a steerable medical instrument comprising an articulable distal end. The method  300  can include contacting the distal end to an object within the treatment site. Contacting the distal end can include articulating or navigating the distal end to the object. Contacting the distal end to the object can include drawing the object to the distal end with fluid flow. The method  300  can also include providing aspiration through the second fluid channel to hold the object to the distal end of the second medical instrument. The distal end can include a pocket configured to hold the object. The method  300  can further include performing lithotripsy while the object is held to the distal end of the second medical instrument. The method  300  can further include moving the second medical instrument, while the object is held to the distal end, to reposition the object within the treatment site. 
     In addition to providing irrigation through the first medical instrument at block  306  and aspiration through the second medical instrument  308 , the method  300  may also include providing irrigation through the second medical instrument. The second medical instrument can include one or more additional fluid channels for providing irrigation, in addition to the second fluid channel for providing aspiration. See, for example, the device of  FIGS. 26A, and 26B . 
       FIG. 22B  is a flowchart illustrating an embodiment of another method  350  for administering directed fluidics during a medical procedure, such as an object removal procedure. In some examples, the object removal procedure is a procedure for removing a kidney stone from a kidney. The method  350  can be also be implemented in other types of medical procedures and in other treatment sites. In some embodiments, the method  350  is implemented in a robotic medical system, for example, any of the systems described above with reference to  FIGS. 1-15 . 
     In the method  350 , both irrigation and aspiration are provided through a single medical instrument, for example, as described above, for example, with reference to  FIG. 21B . The medical instrument can be similar to the medical instrument  700  described below with reference to  FIGS. 26A and 26B . 
     The method  350  begins at block  350 . At block  352 , a first medical instrument is inserted into a treatment site. The first medical instrument can be inserted through a lumen of the patient. In the example of kidney stone removal, the patient lumen may be the ureter. In some examples, the first medical instrument can be inserted percutaneously into the treatment site. The first medical instrument can be an endoscope, nephroscope, catheter, or other type of medical instrument. The first medical instrument can be articulable. In some examples, the first medical instrument is not articulable. In some embodiments, the first medical instrument can include one or more working channels configured to receive various tools (e.g., lithotripters, basket retrieval devices, forceps, etc.) therethrough. The first medical instrument can include at least one first fluid channel and at least one second fluid channel. The first fluid channel and the second fluid channel can be configured to provide fluidics to the treatment site during the medical procedure. In some instances, the distal end of the first medical instrument can be brought into contact with the object to be removed. 
     At block  354 , irrigation is provided through the first medical instrument. For example, irrigation can be provided through the first fluid channel of the first medical instrument. The first fluid channel can be connected to an irrigation source as described above. 
     At block  356 , aspiration is provided through the first medical instrument. For example, aspiration can be provided through the second fluid channel of the first medical instrument. The second fluid channel can be connected to a collection container through a vacuum as described above. In some instances, the order of block  354  and block  356  can be reversed. In some instances, block  354  and block  356  can be performed at the same time. In some instances, block  354  and block  356  can be performed alternatingly, such that irrigation is provided, followed by aspiration, in a series of repetitive steps, for example. 
     At block  358 , the method  350  determines a characteristic of either the irrigation or the aspiration as described above. At block  360 , the method  350  selects (e.g., sets or adjusts) a characteristic of the other of the irrigation or aspiration based on the characteristic of the irrigation or aspiration determined at block  358 . 
     The method  350  illustrates that in some examples, directed fluidics can be provided through a single medical instrument, such as the instrument shown in  FIGS. 26A and 26B . In some embodiments, a second medical instrument can also be employed during the procedure to perform other tasks, as described above. For example, a second instrument can be a ureteroscope, through which a lithotripter can be deployed for breaking up the object to be removed. 
       FIG. 23  provides a flowchart illustrating an embodiment of another method  400  for directed fluidics during a medical procedure, such as an object removal procedure. In some examples, the object removal procedure is a procedure for removing a kidney stone from a kidney. The method  400  can be also be implemented in other types of medical procedures and in other treatment sites. In some embodiments, the method  400  is implemented in a robotic medical system, such as any of the systems described above with reference to  FIGS. 1-15 . In some instances, the method  400  can be performed together with the method  300  of  FIG. 22A  and/or the method  350  of  FIG. 22B . 
     The method  400  begins at block  402 . At block  402 , a first medical instrument is positioned into a treatment site. The first medical instrument can be inserted through a lumen of the patient. In the example of kidney stone removal, the patient lumen may be the ureter. In some examples, the first medical instrument can be inserted percutaneously into the treatment site. The first medical instrument can be an endoscope, nephroscope, catheter, or other type of medical instrument. The first medical instrument can be articulable. In some examples, the first medical instrument is not articulable. In some embodiments, the first medical instrument can include one or more working channels configured to receive various tools (e.g., lithotripters, basketing devices, forceps, etc.) therethrough. The first medical instrument can include at least one first fluid channel. The first fluid channel can be configured to provide fluidics to the treatment site during the medical procedure. 
     At block  404 , a second medical instrument is positioned into a treatment site. The second medical instrument can be inserted through a lumen of the patient. In the example of kidney stone removal, the patient lumen may be the ureter. In some examples, the second medical instrument can be inserted percutaneously into the treatment site. The second medical instrument can be an endoscope, nephroscope, catheter, or other type of medical instrument. The second medical instrument can be articulable. In some examples, the second medical instrument is not articulable. The second medical instrument can include one or more working channels configured to receive various tools (e.g., lithotripters, basket retrieval devices, forceps, etc.) therethrough. The second medical instrument can include at least one second fluid channel. The second fluid channel can be configured to provide fluidics to the treatment site during the medical procedure. 
     In some instances, the order of block  402  and block  404  can be reversed. In some instances, block  402  and block  404  can be performed at the same time. 
     In some instances, the first and second medical devices are positioned into the treatment site via different methods of access. For example, the first medical instrument may be inserted through a patient lumen and the second medical instrument may be inserted percutaneously, or vice versa. As another example, the first medical instrument can be inserted into the treatment site through a first patient lumen, and the second medical instrument can be inserted into the treatment side through a second patient lumen different than the first patient lumen. As another example, the first medical device can be inserted through a first percutaneous access, and the second medical device can be inserted through a second percutaneous access different than the first percutaneous access. In some examples, the first and second medical devices are inserted through the same patient lumen or through the same percutaneous access. 
     In some instances, the first and second medical devices are positioned into the treatment site such that the distal ends of the first and second medical devices are separated within the treatment site. For example, the distal end of the first medical device can be positioned antegrade of the object to be removed, and the distal end of the second medical device can be positioned retrograde of the object to be removed. As another example, the distal end of the first medical device can be positioned retrograde of the object to be removed, and the distal end of the second medical device can be positioned antegrade of the object to be removed. In some instances, the first and second medical devices are positioned such that the object is positioned between the distal ends of the first and second medical devices. 
     At block  406 , irrigation is provided through a first aperture of the first medical instrument in a first fluid flow direction. The first fluid flow direction can be, in some embodiments, a direction normal to the first aperture. The first fluid flow direction can be a general flow direction of fluid exiting the first fluid aperture. At block  408 , aspiration is provided through a second aperture in the second medical instrument. In some instances, the order of block  406  and block  408  can be reversed. In some instances, block  406  and block  408  can be performed at the same time. 
     At block  410 , the first and/or second medical instruments are manipulated such that the first flow direction is oriented toward the second aperture of the second medical instrument. Manipulating the first and/or second medical instruments can include manipulating the first and/or second medical instruments remotely and/or robotically. Manipulating the first and/or second medical instruments can include moving the first and/or second medical instruments such that the first fluid flow direction is oriented towards or pointed at the second fluid aperture. 
     According to the method  400 , the fluid flow is oriented from the first medical instrument toward the second medical instrument, which can provide one or more of the benefits described above. 
     The method  400  can include one or more additional steps. For example, the method  400  can include determining the position and/or orientation of the distal ends of the first and/or second medical instruments. The first and/or second medical instruments can include position sensors on the distal ends thereof. The position sensors can be EM sensors. The EM sensors can be configured to provide position information regarding the distal ends of the first and second medical devices as well as orientation information regarding the distal ends of the first and second medical instruments. Other types of position and orientation sensors, such as a shape sensing fiber, for example, can be used. An output of the position sensors can be used to orient the first and second medical instruments. 
     In some implementations of the method  400 , block  410  occurs automatically. For example, the positions and orientations of the distal ends of the first and second medical instruments can be determined, and the first and second medical instruments can be automatically manipulated. For example, the orientation of first medical instrument can be automatically manipulated so as to track the position of the second medical instrument. That is, as the second medical instrument moves, the orientation of the first medical instrument is automatically adjusted such that the first fluid flow direction remains pointed at or oriented toward the second medical instrument. This can help ensure that the fluid flow remains oriented in the proper direction. 
       FIG. 24  is a flowchart illustrating an embodiment of a method  500  for holding and repositioning an object using directed fluidics during a medical procedure, such as an object removal procedure. In some examples, the object removal procedure is a procedure for removing a kidney stone from a kidney. The method  500  can be also be implemented in other types of medical procedures and in other treatment sites. In some embodiments, the method  500  is implemented in a robotic medical system, such as any of the systems described above with reference to  FIGS. 1-15 . In some instances, the method  500  can be performed together with the method  300  of  FIG. 22A , the method  350  of  FIG. 22B , and/or the method  400  of  FIG. 23 . In some instances, the method  500  can be employed using the medical instrument of  FIGS. 26A and 26B . 
     The method  500  begins at block  502 . At block  502 , a first medical instrument is positioned into a treatment site. For example, the first medical instrument can be inserted through a lumen of the patient. In the example of kidney stone removal, the patient lumen may be the ureter. In some examples, the first medical instrument can be inserted percutaneously into the treatment site. The first medical instrument can be an endoscope, nephroscope, catheter, or other type of medical instrument. The first medical instrument can be articulable. In some examples, the first medical instrument is not articulable. In some embodiments, the first medical instrument can include one or more working channels configured to receive various tools (e.g., lithotripters, basket retrieval devices, forceps, etc.) therethrough. The first medical instrument can include at least one first fluid channel. The first fluid channel can be configured to provide fluidics to or from the treatment site during the medical procedure. 
     At block  504 , a distal end of the first medical instrument is brought into contact with the object to be removed. Contacting the distal end to the object can include articulating or navigating the distal end to the object. In some instances, articulation or navigation of the first medical instrument is achieved robotically, for example, through manipulation of the first medical instrument with an instrument device manipulator or robotic arm to which the first medical instrument is attached. In some instances, articulation or guidance is controlled by a physician controlling the robotic system. In some instances, articulation or guidance is automatically determined by the robotic system. For example, the robotic system can determine the position of the object and the first medical instrument and navigate the first medical instrument to the object. Contacting the distal end to the object can include drawing the object to the distal end with fluid flow, for example with aspiration through the first medical instrument and/or irrigation provided through a second medical instrument. 
     At block  506 , aspiration is provided through the first medical instrument to hold the object to the distal end of the first medical instrument. Aspiration can be provided with a vacuum connected to the first medical instrument. The vacuum can be configured to apply a negative pressure that draws the fluid from the treatment site, through the first medical instrument. In another example, the vacuum can be replaced with a pump, such as peristaltic pump. The pump can be used to move fluid from the treatment site, through the first medical instrument. As fluid is aspirated through the first medical instrument, the fluid flow can hold the object to the distal end of the first medical instrument. In some instances, the first medical instrument can include a pocket (or other receptacle or holding device) on the distal end thereof to help secure the object. See, for example,  FIGS. 26A and 26B . 
     At block  508 , the first medical instrument is moved within the treatment site to reposition the object. During movement, aspiration can be maintained to hold the object to the distal end. Movement can be accomplished robotically. Movement can be automatic (e.g., following a preprogramed motion or moving to a preprogramed position) or based on physician input or control. In some instances, the first medical instrument is used to move the object to a location within the treatment site better suited for lithotripsy. For example, the object can be moved to a location where the fragments can more easily be collected or where there is more space in which to work. As another example, the object can be moved away from sensitive regions of the patient&#39;s anatomy. In some embodiments, block  508  can be omitted. That is, in some embodiments, the object need not be repositioned within the treatment site. 
     At block  510 , lithotripsy is performed on the object with a second medical instrument while providing irrigation with the second medical instrument. Further, lithotripsy can be performed while the object is held to the distal end of the first medical instrument medical instrument. The fluid flow from the second medical instrument to the first medical instrument can serve to hold the object during lithotripsy as well as to direct fragments and dust into the first fluid instrument for aspiration and removal. The fluid flow can also maintain a clear visual field which can assist the physician in performing the procedure. 
     The method  500  can include one or more additional steps. For example, the method  500  can include providing irrigation through the first medical instrument. The first medical instrument may include one or more additional fluid channels (in addition to a first fluid channel for providing aspiration) for providing irrigation. The additional fluid channels may be arranged, for example, as shown in the device of  FIGS. 26A and 26B  described below. The outflow of irrigation can be oriented away (e.g., radially away) from the distal end of the first medical instrument. 
     D. Example Systems and Devices for Directed Fluidics. 
       FIG. 25  is a block diagram illustrating an embodiment of a system  600  for employing directed fluidics during a medical procedure, such as an object removal procedure. In some instances, the methods  300 ,  400 ,  500  described above can be implemented using the system  600 . Additionally, the system  600  may form part of any of the robotic systems described above with reference to  FIGS. 1-15 . 
     As illustrated, the system  600  includes a first medical instrument  616 , a second medical instrument  620 , a pump  608  connected to the first medical instrument  616 , a vacuum  612  connected to the second medical instrument  620 , and a directed fluidics module or fluidics control system  602  connected to the pump  608  and the vacuum  612 . The directed fluidics control system  602  can be configured to control the pump  608  and the vacuum  612  to provide directed fluidics (e.g., irrigation and aspiration) to the treatment site through the first and second medical instruments  616 ,  620 . 
     The first medical instrument  616  can be configured to be inserted into the treatment site via a patient lumen. Alternatively, the first medical instrument  616  can be configured to be inserted into the treatment site percutaneously. The first medical instrument  616  can be an endoscope (such as a ureteroscope), a catheter (such as a steerable or non-steerable catheter), a nephroscope, or other type of medical instrument as described herein. The first medical instrument  616  can include a first fluid channel for providing fluidics (irrigation or aspiration). In the illustrated embodiment, the first medical instrument is attached to the pump  608  for providing irrigation. The pump  608  is attached to an irrigation source  610 , which provides irrigant (e.g., a saline solution) to be pumped through the first medical instrument and into the treatment site. In some examples, the pump  608  is a peristaltic pump. In some embodiments, the pump  608  can be replaced with a vacuum which applies a vacuum pressure to draw the irrigant from the irrigation source  610  and out through the first medical instrument  616 . 
     The first medical instrument  616  can be connected to a first instrument device manipulator  624 . The first instrument device manipulator  624  can be robotically controlled to manipulate the first medical instrument  616 . For example, the first medical instrument  616  can be articulable or steerable, and the first instrument device manipulator  624  can be used to articulate or steer the first medical instrument. Further, the first medical device manipulator  624  can be attached to a robotic arm that is configured to insert or retract the first medical device  616  into or out of the treatment site. Examples of instrument device manipulators are described above with reference to  FIGS. 1-15 . The first medical device  616  can include one or more working channels through which additional tools, such as lithotripters, basket retrieval devices, forceps, etc., can be introduced into the treatment site. 
     The second medical instrument  620  can be configured to be inserted into the treatment site via a percutaneous access. Alternatively, the second medical instrument  620  can be configured to be inserted into the treatment site via a patient lumen. The second medical instrument  620  can be an endoscope (such as a ureteroscope), a catheter (such as a steerable or non-steerable catheter), a nephroscope, or other type of medical instrument as described herein. The second medical instrument  620  can include a second fluid channel for providing fluidics (irrigation or aspiration). In the illustrated embodiment, the second medical instrument is attached to the vacuum  612  for providing aspiration. The vacuum  612  can be configured to apply a negative pressure to draw fluid out of the treatment site. The vacuum  612  is connected to a collection container into which withdrawn fluid is collected. In some examples, the vacuum  612  can be replaced with a pump which pumps liquid from the treatment site, through the second medical instrument  620 , and into the collection container  614 . 
     The second medical instrument  620  can be connected to a second instrument device manipulator  626 . The second instrument device manipulator  626  can be robotically controlled to manipulate the second medical instrument  620 . For example, the second medical instrument  620  can be articulable or steerable, and the second instrument device manipulator  626  can be configured to articulate or steer the second medical instrument  620 . Further, the second medical device manipulator  626  can be attached to a robotic arm that is configured to insert or retract the second medical device  620  into or out of the treatment site. The second medical device  620  can include one or more working channels through which additional tools, such as lithotripters, basket retrieval devices, forceps, etc., can be introduced into the treatment site. 
     In some embodiments, fluidics are provided through only one of the first medical instrument  616  or the second medical instrument  620 , with the instrument providing both irrigation in aspiration. The instrument providing fluidics can be inserted percutaneously into the patient. In some embodiments, the instrument can be similar to the instrument shown in  FIGS. 26A and 26B . The other of the first medical instrument  616  or the second medical instrument  620  may not provide fluidics and may be used for other functionality, such as breaking up the object to be removed. 
     The fluidics control system  602  may include a processor  604  and a memory  606 . The memory  606  can include instructions that configure the processor  604  to determine a characteristic of one of the irrigation and the aspiration, and control a characteristic of at least one of the pump or the vacuum based on the determined characteristic. The determined characteristic can be, for example, an instantaneous flow rate of the irrigation or aspiration. The characteristic can be an average flow rate of the irrigation or aspiration over a time interval. The time interval can be, for example, 1.0 seconds, 2.5, second, 5 second, 10 second, 15 seconds or longer, as well as intervals above and below the listed values. The characteristic can be a volume of fluid irrigated or aspirated during a time interval, such as, for example, any of the time intervals listed above. The characteristic can be an instantaneous fluid pressure associated with the irrigation or aspiration. The characteristic can be an average fluid pressure associated with the irrigation or aspirations over a time interval, such as, for example, any of the time intervals listed above. The fluid pressure can be, for example, a fluid pressure within the first fluid channel, a fluid pressure within the second fluid channel, or a fluid pressure within the treatment site itself. 
     In some instances, the characteristic is determined using one or more sensors, such as the sensors  618 ,  622  on the first and second medical instruments  616 ,  620 , respectively. The sensor  618  can be positioned, for example, in a first fluid channel of the first medical instrument  616  or on the first medical instrument  616  itself. The sensor  622  can be positioned in a second fluid channel of the second medical instrument  620  or on the second medical instrument  620  itself. In some embodiments, one or both of the first and second medical instruments  616 ,  620  includes a plurality of sensors  616 ,  622 . The sensors  618 ,  622  can be flow rate sensors, pressure sensors, or other sensors for determining a characteristic of the irrigation or aspiration. An output from the sensors  616 ,  622  can be connected to the processor  604 , such that the processor  604  can use the output of the sensors  618 ,  622  to determine the characteristic. In some instances, the characteristic is determined from the pump  608  or vacuum  612  supplying the irrigation or aspiration. For example, the characteristic can be determined based on a flow rate set by the pump  608  or a vacuum pressure applied by the vacuum  612 . In some instances, the characteristic is calculated from one or more known or measured parameters. For example, the characteristic can comprise volume of irrigant within the treatment site calculated based on the amount of irrigant pumped into and/or aspirated from the treatment site. 
     In some embodiments, the sensors  618 ,  622  comprise position sensors configured to provide positional information regarding the first and second medical instruments  616 ,  620 . The position sensors can provide 3-degree of freedom position information (e.g., x, y, and z coordinates) or 6-degree of freedom position information (e.g., x, y, and z coordinate and pitch, roll, and yaw angles). The position sensors  618 ,  622  can be for example, EM sensors, shape sensing fibers, or other types of position sensors, including accelerometers, gyroscopes, etc. 
     In some embodiments, the memory  606  includes instructions that further configure the processor  604  to calculate a position of a first position sensor to determine a position of the first medical instrument  616 , calculate a position of s second position sensor to determine a position of the second medical instrument  620 , and manipulate the first or second medical instruments  616 ,  620  such that an outflow aperture of the first medical instrument  616  oriented towards an inflow aperture of the second medical instrument  620 . 
     One or both of the first and second medical instruments  616 ,  620  can be configured to provide both irrigation and aspiration. For example, as illustrated in  FIG. 25 , the second medical instrument  620  can be connected to the vacuum  612  for providing aspiration and may also be connected to the pump  608  (via the dotted line) to provide irrigation. In this embodiment, the second medical instrument  620  can include an additional fluid channel for providing irrigation. An example of a medical instrument  700  including a first fluid channel for providing aspiration or irrigation and an additional fluid channel for providing the other of aspiration or irrigation is shown in  FIGS. 26A and 26B  below. 
       FIGS. 26A and 26B  are perspective and cross-sectional views of a distal end of a medical instrument  700  configured to provide aspiration and irrigation during an object removal procedure. The medical instrument  700  can be used as any of the first and/or second medical instruments described above. The medical instrument  700  can be inserted into the treatment site percutaneously or through a patient lumen. 
     With reference to  FIGS. 26A and 26B , the medical device  700  can include an elongate body  702  that terminates at a distal end  704 . In the illustrated embodiment, a pocket  706  or recess is formed in a distal face of the distal end. The pocket  706  provides a space into which an object to be removed can be received during the procedure. In some embodiments, aspiration and/or irrigation holds the object in the pocket  706 . The object can be held in the pocket  706  during lithotripsy in order to stabilize and secure the object. As the object is broken apart through lithotripsy, the fragments and dust can be aspirated through the medical instrument  700 . 
     The medical instrument  700  can include a fluid channel  708  (see  FIG. 26B ). The fluid channel  708  can terminate at a distal end with a fluid orifice  710 . The fluid channel  708  can be used for aspiration or irrigation. In one example, the fluid channel  708  is used for aspiration, and fluid drawn into the fluid channel  708  can be used to hold the object within the pocket  706 . 
     The medical instrument  700  may also include one or more additional channels  712  surrounding the fluid channel  708  (see  FIG. 26B ). These additional channels  712  can be configured to provide the other of aspiration or irrigation than the fluid channel  708 . The additional channels  712  may terminate in orifices  714  near the distal end  704  of the medical instrument. The orifices  714  can be positioned in the radial surface of the medical instrument  700  so as to orient flow through the orifices in a radial direction, as shown, for example, in  FIGS. 21A and 21B . In some embodiments, the medical instrument  700  includes four orifices  714 . In some embodiments, the orifices  714  direct fluid in a direction that is orthogonal or substantially orthogonal to a longitudinal axis of the medical instrument  700 . In some embodiments, the orifices  714  direct fluid in a direction that is non-orthogonal or angled with respect to the longitudinal axis of the medical instrument  700 . 
     The medical instrument  700  can be articulable. For example, the medical instrument can include pull-wires (or other mechanisms) for controlling the shape or pose of the medical instrument  700 . 
       FIG. 27  illustrates an embodiment of a robotic system  800  arranged for performing an object removal procedure using directed fluidics. The robotic system  800  may be similar to the robotic systems described above with reference to  FIGS. 1-15 . In the illustrated embodiment, the robotic system includes a plurality of robotic arms  805 . The robotic arms  805  may be configured to manipulate the instruments and tools used during the procedure. As illustrated, the system  800  includes the three robotic arms  805   a ,  805   b ,  805   c . Other numbers of robotic arms  805  can be used in other embodiments. 
     The robotic arms  805   a ,  805   b  can be attached to a first instrument  801 . The first instrument  801  can comprise an outer sheath having a working channel and an inner catheter positioned within the outer sheath. In some embodiments, the robotic arm  805   a  controls the outer sheath and the robotic arm  805   b  controls the inner sheath. The first instrument  801  can be inserted into the patient through a patient lumen. As illustrated, the robotic arms  805   a ,  805   b  can insert the first instrument  801  into the patient&#39;s lower abdomen through the urethra. In some embodiments, insertion is performed along a virtual rail as described above. After insertion into the urethra, using control techniques as described above, the first instrument  801  may be navigated into the treatment site (e.g., the bladder, ureters, and/or kidneys) for diagnostic and/or therapeutic applications. 
     The robotic arm  805   c  can be attached to a second instrument  802 . In some embodiments, the second instrument  802  can comprise an outer sheath having a working channel and an inner catheter positioned within the outer sheath. In some embodiments, multiple robotic arms can be used to manipulate the second instrument  802 . In the illustrated embodiment, the second instrument  802  is inserted percutaneously (i.e., laparoscopically) into the treatment site. 
     With the first and second instruments  801 ,  802  positioned by the robotic arms  805  as shown in  FIG. 27 , the system  800  may be configured to implement directed fluidics as described above. For example, the first and second instruments  801 ,  802  can be used to provide irrigation and aspiration to the treatment site as described above. 
       FIG. 27  provides one example of a robotic system  800  configured for directed fluidics. Other systems, including other numbers or types of robotic arms, other numbers or types of medical instruments, and/or other methods for inserting and controlling the instruments are possible. 
     3. Implementing Systems and Terminology. 
     Implementations disclosed herein provide systems, methods and apparatuses for removing an object from a treatment site of a patient, and in particular to methods and systems that employ directed fluidics during an object removal procedure. Directed fluidics can include controlling various features of fluid flow (e.g., rate, direction, pressure, etc.) of irrigation and/or aspiration through a treatment site, and/or separating an inflow point of irrigation from an outflow point of aspiration to facilitate an object removal procedure. In some examples, directed fluidics involves controlling a flow direction from an inflow point to an outflow point so as to hold or stabilize an object during the procedure. 
     It should be noted that the terms “couple,” “coupling,” “coupled” or other variations of the word couple as used herein may indicate either an indirect connection or a direct connection. For example, if a first component is “coupled” to a second component, the first component may be either indirectly connected to the second component via another component or directly connected to the second component. 
     The phrases and features used herein referencing specific computer-implemented processes/functions described herein may be stored as one or more instructions on a processor-readable or computer-readable medium. The term “computer-readable medium” refers to any available medium that can be accessed by a computer or processor. By way of example, and not limitation, such a medium may comprise random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory, compact disc read-only memory (CD-ROM) or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. It should be noted that a computer-readable medium may be tangible and non-transitory. As used herein, the term “code” may refer to software, instructions, code or data that is/are executable by a computing device or processor. 
     The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is required for proper operation of the method that is being described, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. 
     As used herein, the term “plurality” denotes two or more. For example, a plurality of components indicates two or more components. The term “determining” encompasses a wide variety of actions and, therefore, “determining” can include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” can include resolving, selecting, choosing, establishing and the like. 
     The phrase “based on” does not mean “based only on,” unless expressly specified otherwise. In other words, the phrase “based on” describes both “based only on” and “based at least on.” 
     The previous description of the disclosed implementations is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these implementations will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the scope of the invention. For example, it will be appreciated that one of ordinary skill in the art will be able to employ a number corresponding alternative and equivalent structural details, such as equivalent ways of fastening, mounting, coupling, or engaging tool components, equivalent mechanisms for producing particular actuation motions, and equivalent mechanisms for delivering electrical energy. Thus, the present invention is not intended to be limited to the implementations shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.