Patent Publication Number: US-2019175288-A1

Title: System and apparatus for endoscopic deployment of robotic concentric tube manipulators for performing surgery

Description:
RELATED APPLICATION 
     This application is a divisional of U.S. application Ser. No. 14/256,540, filed Apr. 18, 2014, which claims the benefit of U.S. Provisional Application Ser. No. 61/877,552, which was filed on Sep. 13, 2013. 
    
    
     GOVERNMENT RIGHTS 
     This invention was made with government support under National Science Foundation Career Award Grant No. IIS-105433, and under National Institutes of Health Grant No. R01 EB017467. The government has certain rights in the invention. 
    
    
     TECHNICAL FIELD 
     The invention relates to surgical robots. In one particular implementation, the invention relates to a system and apparatus for the endoscopic deployment of robotically controlled concentric tube manipulators for performing surgery. 
     BACKGROUND 
     Recent advances in surgical robotics are enabling less invasive access to the human body through natural orifices. Transoral surgery has been an approach of substantial recent interest, perhaps since the mouth is the largest natural orifice. Many in the surgical community have focused on using Intuitive Surgical, Inc.&#39;s da Vinci™ Surgical System robot for this purpose, while engineering interest has focused on custom designed robot solutions. There has been a recent progression in the surgical robotics community toward designing robots to work through ever smaller orifices. Numerous systems have been designed for colorectal inspection and surgery. Recently, teleoperated and/or cooperative systems have been developed for ear surgery, endonasal surgery, and transurethral bladder surgery. Yet despite the relatively small diameter of the urethra, it is also interesting to note that transurethral surgery was actually one of the earliest surgical robotics applications. 
     Benign prostatic hyperplasia (BPH), or enlargement of the prostate, is the most prevalent symptomatic disease in men, occurring in 8% of men in their 30s, 50% in their 50s, and 90% in their 80s. BPH occurs when the prostate grows large enough that it restricts the flow of urine through the urethra, which passes through the prostate. The goal of a surgical intervention for BPH is to remove prostate tissue surrounding the urethra and thereby enable normal urine flow to resume. Transurethral resection of the prostate (TURP) is the current standard surgical approach for BPH. It is accomplished endoscopically, through the urethra, and prostate tissue is removed in pieces by either sharp dissection or electrocautery. Although the approach to the prostate is minimally invasive, the tools used to remove tissue can cause substantial bleeding (potentially requiring transfusion), long catheterization time, urethral narrowing, and bladder neck narrowing. 
     Holmium Laser Enucleation of the Prostate (HoLEP) is another surgical procedure for treating BPH. HoLEP can alleviate many of these concerns, since the Holmium laser provides an ideal combination of cutting and coagulation. HoLEP enables dissection without significant thermal spread (making HoLEP safer than electrocautery for nearby structures such as nerves), and without substantial blood loss. The reduction in morbidity in HoLEP compared to TURP has been corroborated in a number of clinical studies. These show that HoLEP reduces average catheterization time (2 days to 1 day), hospital stay (3 days to 2 days), and blood loss (eliminates the need for transfusions). The improvement in outcomes is sufficiently compelling that HoLEP is now generally viewed in the urology community as the superior treatment. 
     In spite of this, HoLEP adoption has been slow, and it is currently only conducted in relatively few institutions in the USA compared to TURP, which was conducted approximately 50,000 times in the United States in 2005. The best explanation for why HoLEP has not been more widely adopted is that it is extremely challenging for the surgeon. The challenge is brought about due to the fact that the laser proceeds straight out of the endoscope and can only be aimed by moving the entire endoscope. Since the endoscope must pass through a great deal of soft tissue on the way to the prostate, its maneuverability is limited. Large forces are required to aim the endoscope and the only way to physically manipulate tissue near its tip is to use the tip of the endoscope itself. It is challenging and physically demanding for surgeons to attempt to accurately aim the laser using the endoscope while simultaneously applying large forces to the same endoscope to deform the tissue. 
     SUMMARY 
     The invention relates to a robotic system, method, and apparatus for performing endoscopic surgery. The endoscopic approach can implement a rigid or flexible endoscope to access a target surgical site through a port in the body. These ports can be natural orifices (e.g., mouth, nose, ears, rectum, urethra) or incisions (e.g., chest, abdomen, head). In one implementation, the invention relates to a robotic surgical system that deploys two or more robotic concentric tube manipulators through an endoscope. 
     In one implementation, the robotic surgical system is used to perform transurethral surgery that focuses on the prostate. In this implementation, the robotic surgical system is used to perform a transurethral Holmium Laser Enucleation of the Prostate (HoLEP), which is useful in the management of Benign Prostatic Hyperplasia (BPH). According to one aspect, the robot is adapted for both manual and robotic operation. 
     According to this aspect, a robotic system deploys one or more concentric tube manipulators, at least one of which includes a HoLEP laser, through a conventional endoscope or endoscope tube that is fit with a video camera and an illumination source for facilitating remote viewing. Through this system, the surgeon can manually manipulate the endoscope, which is inserted into the urethra, to place its distal end at a desired location relative to the target. Once positioned, the surgeon can use the concentric tube manipulators to perform the operation. In one particular configuration, the system includes two concentric tube manipulators—one carrying a HoLEP laser and the other carrying a gripper that allows for manipulating tissue, exposing areas for laser dissection, and removing dissected tissues from the patient&#39;s body. 
     Through this operation, the surgeon can control gross motions of the endoscope manually in the usual accustomed manner, while fine motions of the concentric tube manipulators at the endoscope tip are accomplished via controller interface devices, such as thumb joysticks and finger triggers located near the surgeon&#39;s hands. The surgeon can view the endoscope image on a screen, which can be positioned on the back of the robot unit or on a display screen in the operating room. 
     Advantageously, the endoscope that passes into the patient is of the same diameter as that currently used clinically for HoLEP procedures. According to one aspect of the invention, the endoscope advantageously permits delivery of the optics for the camera, the light sources, a concentric tube manipulator carrying the Holmium laser fibers, and a concentric tube manipulator carrying the manipulators, while leaving room for injecting and suctioning irrigation fluids. 
     According to one aspect of the invention, an apparatus for performing endoscopic surgery on a patient includes at least two concentric tube manipulators adapted to carry devices for performing a surgical operation. A transmission operates the concentric tube manipulators. An endoscope tube has a proximal end portion fixed to the transmission. The concentric tube manipulators extend from the transmission through an inner lumen of the endoscope tube and are operable to extend from a distal end of the endoscope tube. 
     According to another aspect of the invention, an apparatus for performing endoscopic surgery on a patient includes an endoscope tube and two or more concentric tube manipulators positioned in an inner lumen of the endoscope tube. The endoscope tube is configured to be delivered transurethrally to a worksite in the patient. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates a system and apparatus for the endoscopic deployment of robotically controlled concentric tube manipulators for performing surgery, according to an aspect of the invention. 
         FIGS. 2 and 3  are isometric views of a robot that forms a portion of the system and apparatus illustrated in  FIG. 1 . 
         FIG. 4  is an exploded isometric view of the robot illustrated in  FIGS. 2 and 3 . 
         FIGS. 5 and 6  are top plan and side elevation views, respectively, of the robot illustrated in  FIGS. 2-4 . 
         FIG. 7  is an exploded isometric view of a portion of the robot illustrated in  FIGS. 2-6 . 
         FIG. 8  is a magnified isometric view of a portion of the robot illustrated in  FIGS. 2-7 . 
         FIG. 9  is an isometric view of a portion of the robot illustrated in  FIGS. 2-8 , with certain portions removed. 
         FIG. 10  is an exploded isometric view of a portion of the robot illustrated in  FIGS. 2-9  with certain portions magnified for clarity. 
         FIG. 11  is a block diagram illustrating the operation of the system and apparatus illustrated in  FIG. 1  and the robot illustrated in  FIGS. 2-10 . 
         FIG. 12  is a schematic illustration comparing the function of the system and apparatus illustrated in  FIG. 1  and the robot illustrated in  FIGS. 2-11  to the function of a conventional endoscope. 
     
    
    
     DESCRIPTION 
     The Surgical System 
       FIG. 1  illustrates an operating room environment in which surgery can be performed. Referring to  FIG. 1 , a system  10  for performing surgery on a patient  12  includes an apparatus  20  in the form of a robot. The robot  20  includes an endoscope  100  that includes an endoscope tube  106  through which one or more concentric tube manipulators  150 , which can also be referred to as “active cannulas” or “concentric tube robots” extend. The robot  20  could include more than two concentric tube manipulators  150 . The robot  20  also includes a transmission  200  for manipulating the operation of the concentric tube manipulators  150 , and a motor pack  300  that includes user interface and control features. 
     The endoscope  100  is releasably connected to a front or distal end of the transmission  200  and the motor pack  300  is releasably connected to a proximal end of the transmission. The robot  20  is supported on a support device, which is illustrated generally at  30 . The support device  30  permits the user (i.e., surgeon) to easily maneuver and position the robot  20 . To achieve this, the support device  30  can be configured (e.g., counterbalanced) so as to negate all or a portion of the weight of the robot  20 . The support device  30  can also have locking features that allow the user to fix the position of the robot  20  so that the user can focus on manipulating the concentric tube manipulators  150  via the user interface and control features  350 . The robot  20  can be connected via cable(s)  312  to a robot interface PC  60  that is used to help program, control, and monitor the operation of the robot  20 . 
     An imaging guidance system  50 , such as an ultrasound system, can be used to aid the user in guiding the robot  20  in the patient  12 . For instance, in an implementation where the system  10  is used to treat BPH, the endoscope can enter the patient  12  via a transurethral insertion and an ultrasound probe  52  can be inserted anally to a position in the vicinity of the prostate. The image guidance can be viewed via the image guidance system  50  itself, or on monitors  54  mounted in the operating room. The monitors  54  can also be used to view video images obtained via the robot  20 . 
     The Robot—Concentric Tube Manipulators 
     Referring to  FIG. 8 , the concentric tube manipulators  150  are small, needle-diameter, tentacle-like robots that include multiple concentric, precurved, elastic tubes. These elastic, curved tubes are typically made of a superelastic metal alloy such as a nickel-titanium alloy (“nitinol”) material. The tubes can, individually or in combination, be rotated about the longitudinal axis of the robot and can be translated along the longitudinal axis of the robot. Through translational movement, the tubes can be retracted into one another and extended from one another. 
     As the precurved tubes interact with one another through relative translational and rotational movement, they cause one another to bend and twist, with the tubes collectively assuming a minimum energy conformation. The precurvature(s) of the tube(s) for a given manipulator  150  can be selected to provide a desired workspace throughout which the tip can access. The curved shape of the distal end of the manipulator  150  is controlled via translation and rotation of each tube at a proximal location (e.g., at its base) outside the patient. The concentric tube manipulators  150  are particularly well suited to natural orifice procedures because their small diameter and remote actuation enable them to operate in areas where bulkier actuation systems (e.g., tendons and pulleys) are not feasible. The size of the manipulator  150  is limited only by the size of nitinol tubes available, which can be an outer diameter of as little as 200 μm or less. 
     In the embodiment illustrated in  FIG. 8 , the robot  20  includes two concentric tube manipulators  150  positioned in the inner lumen  102  of the endoscope tube  106  and are actuatable to protrude from the distal end  104  of the endoscope  100 . Distal ends of the manipulators  150  carry surgical tools, such as a Holmium laser fiber  152  and grippers  154 . The manipulators  150  could carry alternative tools, such as surgical lasers, graspers, retractors, scissors, imaging tips (e.g., endomicroscopy, optical coherence tomography (OCT), spectroscopy), cauterization tips, ablation tips, wrists (for dexterity), curettes, morcelators, knives/scalpels, cameras, irrigation ports, and suction ports. A spacer  156  positioned in the lumen  102  guides the manipulators  150  so their operations don&#39;t interfere with each other. The spacer  156  can be fixed in the lumen  102  of the endoscope  100  by means, such as friction or an adhesive. 
     A first concentric tube manipulator  160  includes three concentric tubes: an outer tube  162 , a first inner tube  164 , and a second, or innermost, inner tube  166  with a tip  168  that carries the laser fiber  152 . A second concentric tube manipulator  170  includes two concentric tubes: an outer tube  172  and an inner tube  174  with a tip  178  that carries the grippers  154 . 
     According to one aspect of the invention and in one particular implementation, the outer tube  172  can be a straight, stiff tube made, for example, of stainless steel. In this configuration, the straight outer tube  172  can be relatively rigid so that the curved inner tube  174  that it carries will conform and straighten when retracted therein. The concentric tube manipulator  170  thus has three degrees of freedom (DOF), i.e., the outer tube  172  can translate axially and the inner tube  174  can translate axially and also rotate. Additionally, according to this aspect, all three tubes  162 ,  164 ,  166  of the concentric tube manipulator  160  can be curved, and each can have two degrees of freedom, i.e., each can translate axially and also rotate. The six DOF manipulator  160  and the three DOF manipulator  170  in combination provide a nine DOF robot  20 . The degrees of freedom of the robot  20  can be adjusted or re-configured by adjusting the number concentric tube manipulators  150 , the number of concentric tubes in each manipulator, or the curved configurations of the concentric tubes. 
     In describing the unique characteristics of the curved concentric tube manipulators  150  described herein, it should be noted and understood what is meant by the terms “axis” or “axial” used in conjunction with the manipulators. Because the curved tubes are coaxial in nature, the axis of the manipulators  150  themselves can be considered to be centered within and follow the curved configuration of the manipulators. Thus, as the curved configuration of the manipulator  150  changes, the axis remains centered in the tubes and follows. However, in this description, reference is also made to rotation of the manipulators  150  and to rotation of the individual concentric tubes that make up the manipulators. In this description, rotation of the manipulators  150  or of any of the concentric tubes that make up the manipulators is meant to refer to rotation about a straight portion of the manipulator that extends through the endoscope  100 . Thus, as the manipulator  150  rotates, the straight portions of the concentric tubes within the endoscope  100  rotate about a common central axis (i.e., coaxially) whereas the curved portions of the tubes outside the endoscope move about that same straight linear axis. 
     The inner tubes  164 ,  166 ,  174  when extended from within the outer tubes  162 ,  172  will resume their precurved configurations due to their superelastic material construction. By controlling the relative translational and rotational positions of their respective tubes, the tips  168 ,  178  can be maneuvered to any position within the workspace defined by the characteristics of the particular tubes. Thus, through careful selection of the tubes used to construct the manipulators  160 ,  170 , their respective workspaces can be tailored to suit the particular surgical task and the physiology of the patient environment in which the task is performed. 
     The Robot—Transmission 
     Referring to  FIGS. 2-6 , the transmission  200  of the robot  20  includes a frame  202  that supports a front end plate  204  and a rear motor interface housing  206 . The frame  202  includes a pair of rails  208  that extend between and interconnect the end plate  204  and the motor interface housing  206 . The end plate  204  and a motor interface housing  206  include bearings  228  that receive opposite ends of a plurality of threaded drive screws  218  and rotation shafts  224 . The bearings  228  support the screws  218  and shafts  224  and facilitate their rotation. 
     The transmission  200  also includes a plurality of tube carriers  210 , each of which is supported on one of the rails  208  and is movable longitudinally along its associated rail. The transmission  200  includes one tube carrier for each individual tube of the manipulators  150 . Thus, for the nine DOF, two manipulator example configuration of the robot  20  illustrated herein, there are five tube carriers  210 —three associated with the first manipulator  160  and two associated with the second manipulator  170 . 
     Referring to  FIG. 7 , each tube carrier  210  includes a frame  212  and a bearing block  214  that interfaces with its associated rail  208  to facilitate its longitudinal movement thereon. As shown in  FIG. 7 , the bearing block  214  can have a downward facing recess with a trapezoidal configuration that mates with a corresponding configuration of a mating portion of the rail  208  upon which it slides. The bearing block  214  can include bearing elements, such as balls or rollers, for facilitating sliding along the rails  208 . In one example configuration, the bearing block  214  and rails  208  could be those commercially available from THK America, Inc. of Schaumburg, Ill., part number HSR8R, which can sustain significant moment loads while continuing to slide freely. 
     Each tube carrier  210  also includes a lead nut  216  for receiving one of the threaded drive screws  218  (see  FIGS. 2-6 ). The lead nut  216  includes internal screw threads that mate with external screw threads on its associated drive screw  218 . Rotation of the drive screw  218  thus can impart movement of the tube carrier  210  and along its associated rail  208 . Rotation of the drive screw  218  in one direction imparts movement of the tube carrier  210  in a first longitudinal direction (e.g., an insertion direction); and rotation of the drive screw in the opposite direction imparts movement of the tube carrier in a second opposite longitudinal direction (e.g., a retraction direction). 
     Each tube carrier  210  also includes a tube holder  220  for supporting a tube of the associated concentric tube manipulator  150 . The tube holder  220  is configured for rotation relative to the tube carrier  210  via a bearing structure. The tube holder  220  is also configured to grasp or otherwise support the associated tube so that the tube can rotate relative to the carrier  210  with the tube holder, but is not permitted to move longitudinally relative to the carrier. Thus, the tube holder  220  is configured such that the tube can rotate relative to the tube carrier  210  and such that the tube translates longitudinally with the tube carrier. 
     Each tube carrier  210  also includes a sleeve  222  with a central bore for receiving an associated rotation shaft  224  (see  FIGS. 2-6 ). The sleeve  222  is configured to permit the shaft  224  to slide freely through the bore so that the tube carrier  210  can slide freely along its associated rail  208 . The central bore of the sleeve  222  has a configuration (e.g., square in the illustrated embodiment) that mates with the cross-sectional shape of the rotation shaft  224  so that rotation of the shaft imparts rotation of the sleeve. 
     Each tube carrier  210  further includes a gear train  226  including a primary gear mounted for rotation with the sleeve  222  and a secondary gear mounted for rotation with the tube holder  220 . The tube carrier  210  is thus configured such that rotation of the rotation shaft  224  imparts rotation of the tube holder  220  via the gear train  226 . The rotation shaft  224  is thus configured to impart rotation to the manipulator tube of the associated tube holder  220 . 
     From the above description, it will be appreciated that each tube carrier  210  is configured to impart translational movement of its associated manipulator tube via rotation of the associated drive screw  218 , and to impart rotational movement of its associated manipulator tube via rotation of the associated rotation shaft  224 . For translational movement, the tube carrier  210  moves linearly along the length of the transmission frame  202 , driven by the drive screw  218  to travel along its respective rail  208 , and carrying with it the associated manipulator tube. For rotational movement, the tube holder  220  rotates within the tube carrier  210 , driven by the rotation shaft  224  via the gear train  226 , and the associated manipulator tube rotates with it. 
     The Robot—Motor Pack 
     Referring to  FIG. 10 , the motor pack  300  is connectable to the motor interface housing  206  of the transmission  200  by means  232 , such as a quick release latch. The motor pack  300  and transmission  200  include pins  240  and corresponding guide holes  242  that mate with each other to guide the motor pack to the correct position on the transmission. The latch  232  is actuatable to lock the transmission  200  and motor pack  300  in this desired position. 
     Referring to  FIGS. 9 and 10 , the motor pack  300  includes motors  302  for imparting rotation to the drive screws  218  and rotation shafts  224 . A separate individual motor  302  is provided for each drive screw  218  and rotation shaft  224 . Since each drive screw  218  and rotation shaft  224  is associated with one degree of freedom of the robot  20 , each motor  302  is also associated with one degree of freedom of the robot. Therefore, the degrees of freedom of the robot  20  can be controlled individually through actuation of the motors  302 . It therefore follows that, for the nine DOF robot  20  of the illustrated embodiment, the motor pack  300  includes nine motors  302 . 
     As shown in  FIG. 9 , the motor pack  300  includes printed circuit boards  370  that include pin sockets  372  for receiving integrated circuit (IC) chips (not shown), such as motor controllers, processors, video controllers, etc., for implementing the control functions of the robot  20  and for communicating with the robot interface PC  60 . Wiring sockets  374  receive corresponding cable plugs (not shown) that wire the motors  302  to the circuit boards  370  and also connect the wires of the cable(s)  312  to the circuit boards. 
     The motors  302  can be of any desired configuration, such as a brushless DC stepper motor configuration. In one example configuration, the motors  302  can be brushless 8 Watt DC motors equipped with  29 : 1  planetary gear heads. These motors can have a high power to weight ratio in comparison with other motors in their class. The motors  302  are mounted in the motor pack  300  so that they align axially with, and connect automatically to, their corresponding drive screw  218  or rotation shaft  224  when the motor pack  300  is connected to the interface housing  206 . This automatic connection is facilitated by couplings  230  that have components connected to the drive screws  218 , rotation shafts  224 , and motors  302 . 
     In the example illustrated in  FIG. 10 , the motor couplings  230  are Oldham couplings, which are well known in the art as being shaft couplings that are simple, secure, reliable, and that allow for some misalignment in the shafts. Each coupling  230  includes a female coupler  234  associated with its associated drive screw  218  or rotation shaft  224 , and a male coupler  236  associated with its associated motor  302 . One or both of the male and female couplers  234 ,  236  can be movable axially against the bias of a spring. In the embodiment illustrated in  FIG. 10 , the female coupler  234  is so biased by a wave spring  238 . 
     The female couplers  234  include a slot for receiving a tab of the corresponding male coupler  236  Through the engagement between the tab and slot, the male coupler can transmit rotational force from the associated motor  302  to the associated screw/shaft  218 ,  224 . Since the slot in the female coupler  234  extends laterally through the entire coupler, the tab in the male coupler  236  can slide laterally in the slot and can even protrude partially from the slot. This is the essence of the Oldham coupling design, which allows the couplings  320  to account for lateral misalignments between the motors  302  and screw/shafts  218 ,  224 . 
     When the motor pack  300  is assembled with the transmission  200 , the guide pins  240  and holes  242  guide the motor pack onto the transmission and the latches  232  lock the motor pack onto the transmission. As this occurs, the male couplers  236  on the motor pack  300  move into engagement with the corresponding female couplers  234  on the transmission  200 . If the male coupler tabs happen to align with and enter the female coupler slots, the coupling takes place immediately. If not, the female couplers are deflected axially against the bias of the wave spring  238 . In the initial set up of the robot  20 , the motors  302  can be operated to cause rotation of the male couplers  236 , which will bring the male and female couplers into alignment, at which time, the female coupler  234  will move axially under the bias of the wave spring  238  so that the male coupler tab enters the female coupler slot. Through the couplings  230  of the transmission  200  and the quick release latches  232  of the motor pack  300 , the motor pack can be attached to the transmission  200  and the motors  302  can be coupled to the screws  218  and shafts  224  in a quick, easy, and reliable manner. 
     The Robot—Biocompatibility 
     The endoscope  100 , transmission  200 , and concentric tube manipulators  150  can be designed to be both sterilizable and biocompatible, constructed entirely from autoclavable and biocompatible components. For example, the materials used to construct these components can be either biocompatible polymers (e.g., Ultem® or PEEK®), stainless steel (which would be passivated before clinical use), aluminum (which would be anodized before clinical use), or nitinol (in the case of the manipulators  150 ). Certain connections between the components can be achieved using a biocompatible and autoclavable bonding agent or glue (e.g., Loctite®, M-21 HP medical device epoxy agent). All of these materials can withstand sterilization in an autoclave. 
     Referring to  FIG. 1 , the robot  20  can incorporate a sterile bag  310  that helps isolate the motor pack  300  from the surgical environment. The sterile bag  310  has an opening sized so that the edges coincide with the dimensions of the engaging surfaces of the motor pack  300  and motor interface housing  206 . Thus, when the motor pack  300  is connected to the transmission  200 , the sterile bag  310  is clamped in place. To facilitate this connection and promote a sterile barrier, a sterile ring or gasket can be provided between the motor pack  300  and transmission  200 . The bag  310  can have openings through which the control handles  350  can extend, and is tied or otherwise drawn closed around robot cabling  312 . 
     With the sterile bag  310  connected as shown in  FIG. 1 , the male couplings  236  (See  FIG. 10 ) on the motor pack  300  are left exposed so that they can engage and mate with the female couplings  234  on the transmission  200 . When the motor pack  300  is connected to the transmission  200 , the couplings  230  are positioned in an enclosure formed by the motor pack  300  and the motor interface housing  206 . The manner in which the female and male couplings  234 ,  236  are secured to the transmission  200  and motor pack  300 , respectively (e.g., using gaskets, bushings, etc.) creates a tortuous path that helps isolate any non-sterile portions of the couplings  230  from the surgical environment. 
     To set up the robot  20  in the operating room, the endoscope  100 , transmission  200 , and concentric tube manipulators  150  are first autoclaved to sterilize the unit. The sterile bag  310  is attached to the motor pack  300 , which is then secured to the transmission  200  via the latches  232 . The sterile bag  310  is then pulled over the motor pack  300  and sealed using means, such as sterile tape. The motor pack  300  is thereby isolated from the sterilized endoscope  100 , transmission  200 , and concentric tube manipulators  150 . 
     Procedure Specific Configurations 
     The robot  20  can be configured to perform certain endoscopic surgical procedures through the configuration of the endoscope tube  106 , the concentric tube manipulators  150 , and the tools that the manipulators carry. In the illustrated example embodiment, the robot  20  is configured for transurethral treatment of benign prostatic hyperplasia (BPH). In this configuration, the laser  152  carried at the tip  168  of the first concentric tube manipulator  160  is a Holmium laser, which is a type of laser commonly used for tissue ablation. In this particular configuration of the robot  20 , the laser  152  is for performing a Holmium laser enucleation of the prostate (HoLEP) procedure. The six DOF configuration of the first concentric tube manipulator  160  provides significant dexterity to the user. The grippers  154  carried at the tip  178  of the second concentric tube manipulator  170  gives the user the ability to manipulate and remove tissue. 
     According to the illustrated example configuration of the invention, the robot  20 , particularly the concentric tube manipulators  150  and the transmission  200 , can be adapted to receive and cooperate with a conventional, commercially available endoscope  100 . In one example, the endoscope  100  can be a Storz Model 27292 AMA endoscope, which is commercially available from Karl Storz Endovision, Inc. of Charlton Mass. Advantageously, this endoscope is currently used clinically for prostate surgery, so its ability to be inserted through the urethra to access and operate on the prostate is proven. In this instance, the transmission  200  can include an adapter  250  specifically designed to connect the conventional endoscope to the transmission. As an additional advantage, this endoscope can include integrated optics  180  and light sources  182 , which are shown in  FIG. 8 . 
     The use of a conventional endoscope in the configuration of the robot  20 , however, is not an absolute requirement. For purposes of this description, reference to the endoscope  100  as a portion of the robot  20  should be considered to describe only the inclusion of a tube commensurate with the endoscope tube  106  of the illustrated conventional endoscope. Whether the robot  20  includes a conventional endoscope is not material. For example, in an alternative configuration, the robot  20  could simply include a custom tube, such as a stainless steel tube, that is either permanently fixed to, or connectable to and removable from, the front end of the robot  20 . This tube would be configured to have similar or identical dimensions as those of the tube  106  of endoscope  100 . This configuration would eliminate the inclusion and associated costs of the commercially available conventional endoscope from the robot  20 . 
     For instance, the robot  20  could be fit with a tube similar or identical to the endoscope tube  106  of the illustrated endoscope  100 , only without the remainder of the endoscope components. In this case, the robot  20  would be fit with the optics  180  and light source(s)  182 . Separate ports for optics/light cabling and the introduction of fluids or other media could also be included in this alternative configuration. In one particular example, spacer  156  can support the concentric tube manipulators  150 , the optics  180 , and the light sources  182  in the inner lumen  102  of the endoscope tube  106 . 
     Additionally, the endoscope tube  106  does not necessarily have a rigid tube construction. The endoscope tube  106  can have a flexible construction that allows for its insertion and delivery along a non-linear or curved path. The flexible tube  106  can be bent or otherwise manipulated by the surgeon to a desired shape calculated to deliver the concentric tube manipulators  150  along a desired path. The concentric tube manipulators  150  will conform to the shape of the tube  106 . To facilitate this construction, the concentric tube manipulators  150  would need to be flexible. The superelastic, nitinol construction of the concentric tubes advantageously accommodates this requirement. 
     The endoscope tube  106  can be sized commensurate with the surgical procedure for which it is intended. Generally speaking, endoscopic procedures can implement an endoscope tube having an outside diameter (O.D.) of about 2-20 mm. Incisions larger than this can begin to reduce the benefit of the minimally invasive approach. For instance, neuroendoscopes can be only a few millimeters in diameter. A bronchoscope can typically be about 4 mm at the tip, but some can be smaller. Colonoscopes are typically 10 mm in diameter or a few millimeters larger. Abdominal endoscopes can be 10-12 mm in diameter, and up to 20 mm in the case of a single port through the navel. Advantageously, if the incision is 3 mm or less, suturing is not necessary. 
     Since nitinol tubes are available with an outer diameter of as little as 200 μm or less, the robot  20  with endoscope tubes  106  having an O.D. as small as 2 mm or potentially less, and carrying two or more concentric tube manipulators  150  can be produced. As the endoscope tube  106  increases in diameter, the diameter of the concentric tube manipulators  150  that can be implemented in the robot  20  also increases. Additionally, as the diameter of the endoscope tube  106  increases, the number of concentric tube manipulators  150  implemented in the robot  20  also increases. Increasing the number of concentric tube manipulators  150  would, of course, increase the size and complexity of the transmission  200  and motor pack  300 . Following these guidelines, the selection of the diameter of the endoscope tube  106  can be commensurate with the procedure being performed and the physiological limitations associated with that procedure. 
     For instance, with regard to the transurethral implementation described in the example embodiments herein, the endoscope  100  can be a 26 FR endoscope, which corresponds to an endoscope tube  106  having an O.D. of 8.66 mm. Endoscopes of this diameter are known to be effective in performing transurethral procedures. The optics  180  and light sources  182  occupy a generally crescent shaped, semi-circular portion of the inner lumen  102  of the endoscope tube  106 . This leaves about half the inner lumen  102 , having a maximum width of about 8 mm and a height of about 4 mm as the space in which to implement the concentric tube manipulators  150 . This space is ample to permit the use of concentric tube manipulators  150  each having an O.D. of up to slightly above 2 mm. 
     As shown in  FIG. 8 , the manipulators  150  along with the spacer  156  fit easily into the inner lumen  102 , leaving ample space for defining a delivery channel in the endoscope tube  106 . The delivery channel defined by the inner lumen  102  can be used to supply an irrigation fluid to the worksite, a distension or insufflation fluid to the worksite, or any other desired solid, liquid or gaseous media to the worksite. For example, surgical procedures of the urethra, bladder, prostate, kidney, etc, typically can involve the use of a liquid, i.e., saline solution, to distend the tissue at the worksite in order to provide space for viewing and for maneuvering the manipulators  150 . Similarly, surgical procedures in the abdomen or chest typically can involve the use of a gas, such as air, carbon dioxide, or helium, to distend or insufflate the tissue at the worksite in order to provide space for viewing and for maneuvering the manipulators  150 . Advantageously, the endoscope  100  of the robot  20  can be configured so that the inner lumen  102  of the endoscope tube  106  defines the delivery port or channel. As an additional feature, the spacer  156  can include a portion that serves as a nozzle for directing the media delivered via the channel of the inner lumen  102 . 
     A robot  20  comprising two or more concentric tube manipulators  150  in an endoscope tube  106  that can access the prostate transurethrally is an unprecedented construction. This is especially true given the fact that the endoscope tube  106  also includes the integrated optics  180 , light sources  182 , and delivery channel. The average male urethra is about 6.0 mm in diameter. The transurethral aspect of the delivery method limits the O.D. of the endoscope tube  106  to slightly greater than 6.0 mm due to the ability of the tissue surrounding the urethra to stretch. The endoscope tube  106  implemented in the robot  20  of the present invention provides all of the functionality described herein in an endoscope tube having an O.D. 26 Fr (8.66 mm), which is about as large as the urethra can accept, given its ability to stretch. 
     Quantifying the advantages of this construction in a transurethral implementation, the robot  20  of the present invention can provide two or more robotically actuated concentric tube manipulators  150  in an endoscope tube  106  that can be delivered transurethrally and that is equipped with optics  180 , light sources  182 , and a delivery channel, wherein the ratio of endoscope tube diameter to concentric tube manipulator diameter is at least 2:1. (In this description, the diameter of the concentric manipulators is considered the O.D. of the largest, i.e., outer, tube.) In fact, depending on factors such as the desired dexterity of the concentric tube manipulator  150  and the size and type of surgical tool carried by the manipulator, the ratio of endoscope tube diameter to concentric tube manipulator diameter can be at least 3:1 or more. 
     Other implementations produce similar advantageous constructions. For example, transnasal skull-based surgery can be used to resect the pituitary gland in order to remove a tumor. In this procedure, the nostril is the natural orifice, which has an opening that is about 16 mm by 35 mm. From there, a passage extends about 100 mm and widens as it approaches the pituitary gland. The size of the sella turcica (the chamber holding the pituitary gland), however, is a comparatively small roughly ellipsoidal space with an 8.5 mm major radius and a 6 mm minor radius. Advantageously, the robot  20  of the present invention can be configured with an endoscope tube  106  sized for accommodation in the space leading to the sella turcica. This endoscope tube  106  can deliver two or more concentric tube manipulators  150  sized and configured to operate within the confines of the sella turcica in order to perform the surgical procedure. Thus, in this scenario, since the endoscope tube  106  can be larger, the ratio of endoscope tube diameter to concentric tube manipulator diameter can be at least 3:1, or significantly higher. 
     As another example, a transoral surgical procedure can be used to perform a pulmonary surgical operation. In this implementation, the natural orifice is the throat. The radius of the bronchi is the limiting factor in determining the size of the endoscope tube  106 . The size of the endoscope tube  106  depends on the requisite degree of penetration into the bronchi. Since the bronchi branch off and narrow, a flexible endoscope tube  106  could facilitate further delivery of the concentric tube manipulators  150 . From there, the concentric tube manipulators  150  can be deployed to perform the procedure. 
     Advantageously, for deep lung penetration, the robot  20  can be configured to implement an endoscope tube on the small end of the range, such as about 3 mm. Even in these small diameter configurations, the ratio of endoscope tube diameter to concentric tube manipulator diameter can be 2:1 or higher. 
     Typical transanal or transabdominal endoscopic procedures typically use endoscopes in the range of 10-12 mm in diameter or larger. The robot  20  can be configured with a similarly sized endoscope tube  106  for these procedures. Due, however, to the compact size of the concentric tube manipulators  150 , using the robot  20  of the present invention to perform these procedures can potentially reduce the requisite size of the endoscope tubes  106 . While perhaps not as significant in the transanal procedure due to the luxury of space in this natural orifice procedure, this can be of tremendous benefit in performing transabdominal procedures because a reduction in scope size yields a reduction in the size of the abdominal incision. 
     Operating the Robot 
     Regardless of the surgical procedure, the robot  20 , supported by the support device  30 , can be maneuvered manually by the surgeon with ease due to the counterbalancing features of the support device. These counterbalancing features can even be configured to suit the surgeon&#39;s preferences by incorporating variable damping into the support device. To perform operations with coarse control, the surgeon can maneuver the entire robot  20  manually in order to maneuver the endoscope tube  106 . An example of a coarse control function may be to insert the endoscope tube  106  through the urethra under the guidance of the imaging (i.e., ultrasound) equipment  50 . These coarse movements of the robot  20  facilitate positioning the distal end  104  of the endoscope  100  at the desired worksite (e.g., the prostate) in the patient  12 . Once the coarse positioning is complete, if the surgeon chooses, the support device  30  can be locked to fix the position of the robot  20  relative to the patient  12  so that fine control can be implemented as described below. 
     Fine control of the robot  20  can be achieved through the robotic operation of the concentric tube manipulators  150 . The surgeon can control the manipulators  150  through the user interface and control features  350  included with the motor pack  300 . These features  350  include a display panel  352  mounted on a rear facing portion of the motor pack  300  in combination with a pair of control handles  360  mounted on opposite sides of the motor pack  300 . Each control handle  360  is associated with a corresponding one of the manipulators  150 . The motor pack  300  can also include one or more pushbuttons  354  for accessing menu-driven features, such different operating modes, system setup, calibration routines, etc. 
     Each control handle  360  has an ergonomically contoured handle portion  362  that facilitates a comfortable and natural feel when grasped. Each control handle  360  also includes a thumb joystick  364  with pushbutton capability, as well as an index finger trigger  366 . The trigger  366  has a configuration that allows for sensing the degree to which the trigger is actuated. For example, the trigger  366  can have an analog configuration, such as a variable resistance configuration, and can provide a percent actuated (e.g., 0-100%) indication of its degree of actuation. 
     Advantageously, the handle portions  362  have a robust configuration so that they can be grasped and used to manipulate the robot  20  for coarse control, while simultaneously allowing for fine control of the concentric tube manipulators  150  through use of the joystick  364  and trigger  366 . In this manner, the surgeon can employ the robot  20  in a manner suited to his preferences and in response to different operating scenarios. For instance, the surgeon may prefer to locate the distal end  104  of the endoscope  100  at the work site through manual coarse operation of the robot  20 . In doing so, the surgeon may prefer to manually lock the position of the robot  20  via the support device  30  to fix the distal end  104  of the endoscope  100  at the worksite in the patient  12 . The enables the surgeon to perform fine control of the robot  20 , i.e., the manipulators  150 , through actuation of the joystick  364  and/or trigger  366 . 
     Alternatively, the surgeon may choose to leave the support device  30  unlocked so as to allow for performing both coarse and fine operations simultaneously or in combination with each other. As another alternative, two or more surgeons can operate the robot simultaneously, with one surgeon being responsible for coarse manual control and one surgeon being responsible for fine robotic control. 
     As a further example, instead of being mounted on the support device  30 , the robot  20  itself could be mounted on a robotic arm, such a robotic arm of Intuitive Surgical, Inc.&#39;s da Vinci™ Surgical System described above. In this instance, coarse control of the robot  20  could be implemented through operation of the robot arm, and fine control could be implemented via operation of the robot  20  itself. In this alternative implementation, control handles similar or identical to those positioned on the motor pack  300  can be positioned remotely, at or near the robot arm controls so that both the robot arm and the robot  20  can be controlled from the same location. 
     The joystick  364  and trigger  366  can be configured to control operation of the concentric tube manipulators  150  in a variety of manners. In an example configuration, digital and/or analog signals from the joystick  364  and trigger  366  can be mapped to velocities of the tip of the associated concentric tube manipulator  150  with respect to the distal end  104  of the endoscope tube  106 . For each controller  360 , the trigger  366  can be mapped to the axial insertion direction of the manipulator  150  and the two degrees of freedom of the joystick  364  were mapped to the lateral directions. To change the direction of axial motion (insertion vs. retraction) controlled by the trigger  366 , the surgeon presses the push button of the joystick  364 . 
     Real-time control is implemented using known control software, such as xPC Target® and Simulink® software (available commercially from MathWorks, Inc. of Natick, Mass.). A block diagram of the control interface  400  is shown in  FIG. 11 . As shown in  FIG. 11 , the surgeon  402  specifies a desired velocity in task space via displacement of the trigger  366  and joystick  364 . The desired velocity ({dot over (X)} d ) is converted into a desired joint space velocity ({dot over (q)} d ) using a resolved rates algorithm  406  implementing a kinematics model. These velocities are then integrated at  408  to obtain desired joint positions (q d ), which are used for low-level control  410  of the robot  20 , i.e., of the motors  302  that operate the concentric tube manipulators  150 . The surgeon  402  can view the resulting motion of the manipulators  150  on the display  352 , which provides the feedback necessary to allow him/her to operate the robot  20  to perform the desired task. 
     For the illustrated example embodiment, the kinematic models implemented in the resolved rates algorithm  406  are based on the number of tubes (e.g., two, three, etc.) which determines the degrees of freedom (e.g., three, six, etc.) of the concentric tube manipulator  150 . Kinematic models for the two and three concentric tube manipulators of the illustrated example embodiment are described below. Those skilled in the art will appreciate that concentric tube manipulators having additional numbers of tubes would necessitate kinematic models to account for their additional degrees of freedom. 
     Kinematics of the Three Tube Manipulator 
     For the six DOF first concentric tube manipulator  160 , the forward kinematics are solved via the model described in D. C. Rucker et al, A geometrically exact model for externally loaded concentric-tube continuum robots,” IEEE Transactions on Robotics, vol. 26, no. 5, pp. 769-780, 2010, which is hereby incorporated by reference in its entirety. The Jacobian is computed according to D. C. Rucker et al. “Computing Jacobians and compliance matrices for externally loaded continuum robots,” IEEE International Conference on Robotics and Automation, pp. 945-950, 2011, which is hereby incorporated by reference in its entirety. These models are implemented in C++ and sent via user datagram protocol (UDP) to the main controller in Simulink. The six DOF manipulator also requires the implementation of a redundancy resolution algorithm since only the three DOF tip position is to be controlled. Under one approach, redundancy can be resolved by locally minimizing joint speeds. Alternative redundancy resolution approaches could be implemented. 
     Kinematics of the Two Tube Manipulator 
     For the three DOF second concentric tube manipulator  170 , the forward kinematics and hybrid Jacobian can be calculated in closed form in the following manner. The forward kinematics of the two-tube robot with a straight outer tube and a constant curvature inner tube can be written in closed form. Here, it is assumed that the outer tube is sufficiently stiff that the inner tube does not bend it significantly. The inner tube is elastic with constant precurvature κ. The actuation variables are α 1 , which denotes the angular position of the inner tube, β 1  ∈s (where s measures arc length), which is the location where the inner tube is held by its carrier, and β 2  ∈s, which is the location where the outer straight tube is held by its carrier. We define s=0 to be where the manipulators  150  exit the distal end  104  of the endoscope tube  106 , with positive s toward the prostate. Further, let us define l 1  and l 2  to be the physical lengths of the tubes. Consider a fixed frame at the tip of the endoscope  100 , with its z-axis tangent to the endoscopic axis, and its x-axis defined as the direction about which the inner tube curves at α 1 =0. Let us also place a body frame at the tip of the robot with its z-axis tangent to the central axis of the robot at its tip, and its x-axis in the direction about which the tube curves (note that the body frame moves with the robot&#39;s tip as the robot deforms). Using these definitions, the forward kinematics, g st , is given by: 
     
       
         
           
             
               
                 
                   
                     
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     where γ=κ(β1−β2+l1−l2) and r=1/κ. The spatial Jacobian J s  can be defined from the forward kinematics as: 
     
       
         
           
             
               
                 
                   
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     The relationships between the spatial, body, and hybrid Jacobians are defined as: 
     
       
         
           
             
               
                 
                   
                     
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     where Ad gst  is the adjoint transformation, J h  is the hybrid Jacobian, and J b  is the body Jacobian. Using Equations 1 and 3, the hybrid Jacobian can be shown to be: 
     
       
         
           
             
               
                 
                   
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     Using this Jacobian, a singularity robust resolved rates algorithm is implemented. The update step in this algorithm is given as: 
         {dot over (q)} =( J   h   T   J   h +λ 2   I ) −1   J   h   T   {dot over (x)}   (Eq. 5)
 
     where λ 2  is given by: 
     
       
         
           
             
               
                 
                   
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     where ε determines how close to singularity one wishes the system to be before implementing the damping factor, λ max  is the maximum damping factor, and σ m  is the minimum singular value of J h , which indicates the degree to which the Jacobian is conditioned. 
     Experimental Testing 
     The robot  20  of the present invention allows the surgeon to reduce or minimize the degree to which he relies on maneuvering the endoscope  100  itself from outside the patient in order to perform the HoLEP procedure. The surgeon can insert the endoscope  100  to position the distal end  104  of the endoscope tube  106  at the worksite (i.e., the prostate and the intrapelvic space surrounding the prostate). From this position, the surgeon can use the concentric tube manipulators  160 ,  170  to maneuver the laser  152  and grippers  154  locally at the worksite instead of maneuvering the entire robot  20  and endoscope  100  from outside the patient. Advantageously, this can reduce the angle that the surgeon must apply to the endoscope  100  during surgery, which reduces the force that the surgeon must apply to perform the procedure. This can help reduce both the physical demands placed on the surgeon and the trauma applied to the patient. 
     To illustrate this point, referring to  FIG. 12 , an ellipsoid  420  representative of a prostate is accessed by an endoscope  100 . On the left as viewed in  FIG. 12 , it can be seen that the endoscope  100  has to be maneuvered almost 30 degrees in order for the distal end  104  of the endoscope tube  106  to access the peripheral regions of the prostate  420 . These positions would correspond to those available through coarse manual movements of the robot  20 . Such extreme coarse manual movements can be physically taxing on the surgeon and can cause trauma to the patient  12 . 
     Advantageously, as viewed on the right in  FIG. 12 , the tip of the concentric tube manipulator  150  delivered by the endoscope  100  can access the peripheral regions of the prostate  420  without maneuvering the endoscope at all. It can thus be seen that the robot  20  of the present invention offers several improvements to HoLEP surgery. Using the robot  20  can make HoLEP surgery easier to perform and can reduce the time required to perform the procedure. The robot  20  can achieve this by enhancing dexterity at the worksite while at the same time minimizing the surgeons physical effort and the amount of trauma placed on the patient. It will thus be appreciated that, through a combination of coarse manual control and fine robotic control, the robot can provide maximal surgical access to the prostate  420 . 
     From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.