U.S. patent application number 16/256291 was filed with the patent office on 2019-06-13 for system and apparatus for endoscopic deployment of robotic concentric tube manipulators for performing surgery.
The applicant listed for this patent is Vanderbilt University. Invention is credited to Trevor Bruns, Richard Hendrick, S. Duke Herrell, Philip J. Swaney, Robert J. Webster.
Application Number | 20190175288 16/256291 |
Document ID | / |
Family ID | 52668633 |
Filed Date | 2019-06-13 |
View All Diagrams
United States Patent
Application |
20190175288 |
Kind Code |
A1 |
Herrell; S. Duke ; et
al. |
June 13, 2019 |
SYSTEM AND APPARATUS FOR ENDOSCOPIC DEPLOYMENT OF ROBOTIC
CONCENTRIC TUBE MANIPULATORS FOR PERFORMING SURGERY
Abstract
An apparatus (20) for performing endoscopic surgery on a patient
(12) includes at least two concentric tube manipulators (150)
adapted to carry devices (152, 154) for performing a surgical
operation. A transmission (200) operates the concentric tube
manipulators (150). An endoscope tube (106) has a proximal end
portion fixed to the transmission (200). The concentric tube
manipulators (150) extend from the transmission (200) through an
inner lumen (102) of the endoscope tube (106) and are operable to
extend from a distal end (104) of the endoscope tube.
Inventors: |
Herrell; S. Duke;
(Nashville, TN) ; Webster; Robert J.; (Nashville,
TN) ; Bruns; Trevor; (Nashville, TN) ; Swaney;
Philip J.; (Nashville, TN) ; Hendrick; Richard;
(Nashville, TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Vanderbilt University |
Nashville |
TN |
US |
|
|
Family ID: |
52668633 |
Appl. No.: |
16/256291 |
Filed: |
January 24, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14256540 |
Apr 18, 2014 |
10238457 |
|
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16256291 |
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61877552 |
Sep 13, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 1/0016 20130101;
A61B 1/00087 20130101; A61B 34/72 20160201; A61B 2034/301 20160201;
A61B 34/70 20160201; A61B 1/00133 20130101; A61B 2018/225 20130101;
A61B 1/307 20130101; A61B 90/30 20160201; A61B 90/361 20160201;
A61B 1/303 20130101; A61B 34/30 20160201; A61B 1/00131 20130101;
A61B 2034/742 20160201; A61B 34/74 20160201; A61B 2018/2238
20130101 |
International
Class: |
A61B 34/30 20060101
A61B034/30; A61B 1/303 20060101 A61B001/303; A61B 34/00 20060101
A61B034/00; A61B 1/00 20060101 A61B001/00; A61B 1/307 20060101
A61B001/307 |
Goverment Interests
GOVERNMENT RIGHTS
[0002] 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.
Claims
1. An apparatus for performing endoscopic surgery on a patient, the
apparatus comprising: a robot and a robotic arm upon which the
robot is mounted, the robotic arm being operable to coarse movement
of the robot as a whole, the robot comprising: a transmission; a
motor pack connected to the transmission; a controller for
controlling operation of the motors; an endoscope tube connected to
and extending from the transmission; and at least two concentric
tube manipulators connected to the transmission and extending
adjacent to each other at least partially through the endoscope
tube; wherein each concentric tube manipulator has a manipulator
axis and comprises a plurality of nested tubes arranged
concentrically along the manipulator axis, each nested tube being
configured for rotational movement about the manipulator axis
and/or translational movement along the manipulator axis; wherein
each concentric tube manipulator includes at least one nested tube
that has a pre-curved portion configured to assume a pre-curved
configuration when extended relative to the remaining nested tubes,
and to deflect and conform with the remaining nested tubes when
retracted relative to the remaining nested tubes; wherein the
transmission is configured to impart the rotational movement and/or
translational movement to the nested tubes of each concentric tube
manipulator in response to operation of the motors; and wherein the
robot further comprises at least one robot-mounted manually
actuatable control input device operable to provide a control
signal to the controller to operate the motors and control the at
least two concentric tube manipulators; and wherein the apparatus
further comprises at least one manually actuatable remote control
input device located remotely from the robot and the robotic arm,
the at least one remote control input device being operable to
provide a control signal for controlling operation of the robotic
arm and to provide a control signal to the controller to operate
the motors and control the at least two concentric tube
manipulators.
2. The apparatus recited in claim 1, wherein the control signal
that the at least one manually actuatable remote control input
device provides to the controller is indicative of desired
movements of the at least two concentric tube manipulators, the
controller being operative to control operation of the motors in
order to produce via the transmission the at least one of
rotational movement along the manipulator axis and the
translational movement along the manipulator axis that will produce
the desired movements of the at least two concentric tube
manipulators.
3. The apparatus recited in claim 1, wherein the robot-mounted
manually actuatable control input device is mounted on the motor
pack.
4. The apparatus recited in claim 1, wherein the robot further
comprises optics and a light source positioned at the distal end of
the endoscope tube, the light source being operable to illuminate a
workspace of the at least two concentric tube manipulators, and the
optics being operable to provide video of the workspace.
5. The apparatus recited in claim 4, further comprising a spacer
fixed in an inner lumen of the endoscope tube at the distal end of
the endoscope tube, the spacer being configured to support the at
least two concentric tube manipulators in the endoscope tube and
guide the at least two concentric tube manipulators from the distal
end of the endoscope tube.
6. The apparatus recited in claim 5, wherein the spacer comprises a
nozzle for directing fluids through the distal end of the endoscope
tube.
7. The apparatus recited in claim 1, wherein the at least one
manually actuatable remote control input device comprises a
joystick associated with one of the concentric tube manipulators,
and wherein the controller maps the control signal provided by the
joystick to lateral tip movements for the associated concentric
tube manipulator and controls operation of the motors to produce
the lateral tip movements.
8. The apparatus recited in claim 1, wherein the at least one
manually actuatable remote control input device comprises a trigger
associated with one of the concentric tube manipulators, and
wherein the controller maps the control signal provided by the
trigger to axial tip movements for the associated concentric tube
manipulator and controls operation of the motors to produce the
axial tip movements.
9. The apparatus recited in claim 1, further comprising optics and
a light source positioned an inner lumen of the endoscope tube at
the distal end of the endoscope tube, the light source being
operable to illuminate a workspace of the at least two concentric
tube manipulators, and the optics being operable to provide video
of the workspace.
10. The apparatus recited in claim 1, further comprising a spacer
fixed in an inner lumen of the endoscope tube at the distal end of
the endoscope tube, the spacer being configured to support the at
least two concentric tube manipulators in the endoscope tube and
guide the at least two concentric tube manipulators from the distal
end of the endoscope tube.
11. The apparatus recited in claim 10, wherein the spacer comprises
a nozzle for directing fluids from the distal end of the endoscope
tube.
12. The apparatus recited in claim 1, wherein the transmission
comprises a plurality of tube carriers each of which carry one tube
of one of the at least two concentric tube manipulators, each tube
carrier having an associated drive screw and rotation shaft, each
drive screw being coupled to an associated motor that is operable
to rotate the drive screw to cause longitudinal translation of the
tube carrier and its associated tube, each rotation shaft being
coupled to an associated motor that is operable to rotate the
rotation shaft to cause rotation of its associated tube within the
tube carrier.
13. The apparatus recited in claim 1, wherein the endoscope tube
comprises a portion of a conventional endoscope, and wherein the
transmission comprises an adapter for connecting the endoscope to
the transmission.
14. The apparatus recited in claim 1, wherein the endoscope tube
comprises a transurethral endoscope tube for delivering the at
least two concentric tube manipulators transurethrally to a
worksite in the patient, wherein the endoscope tube has an outside
diameter of 6.0 mm or less.
Description
RELATED APPLICATION
[0001] 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.
TECHNICAL FIELD
[0003] 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
[0004] 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.'s da Vinci.TM. 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.
[0005] 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.
[0006] 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.
[0007] 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
[0008] 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.
[0009] 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.
[0010] 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's
body.
[0011] 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'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.
[0012] 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.
[0013] 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.
[0014] 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
[0015] 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.
[0016] FIGS. 2 and 3 are isometric views of a robot that forms a
portion of the system and apparatus illustrated in FIG. 1.
[0017] FIG. 4 is an exploded isometric view of the robot
illustrated in FIGS. 2 and 3.
[0018] FIGS. 5 and 6 are top plan and side elevation views,
respectively, of the robot illustrated in FIGS. 2-4.
[0019] FIG. 7 is an exploded isometric view of a portion of the
robot illustrated in FIGS. 2-6.
[0020] FIG. 8 is a magnified isometric view of a portion of the
robot illustrated in FIGS. 2-7.
[0021] FIG. 9 is an isometric view of a portion of the robot
illustrated in FIGS. 2-8, with certain portions removed.
[0022] FIG. 10 is an exploded isometric view of a portion of the
robot illustrated in FIGS. 2-9 with certain portions magnified for
clarity.
[0023] 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.
[0024] 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
[0025] 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.
[0026] 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.
[0027] 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
[0028] 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.
[0029] 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 .mu.m or less.
[0030] 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'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.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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).
[0039] 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.
[0040] 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.
[0041] 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.
[0042] 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
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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.
[0048] 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.
[0049] 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
[0050] 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.RTM. or PEEK.RTM.), 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.RTM., M-21 HP medical device epoxy agent). All of these
materials can withstand sterilization in an autoclave.
[0051] 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.
[0052] 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.
[0053] 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
[0054] 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.
[0055] 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.
[0056] 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] Since nitinol tubes are available with an outer diameter of
as little as 200 .mu.m 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.
[0061] 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.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] 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.
[0068] 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
[0069] 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'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.
[0070] 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.
[0071] 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.
[0072] 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.
[0073] 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.
[0074] 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.'s da
Vinci.TM. 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.
[0075] 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.
[0076] Real-time control is implemented using known control
software, such as xPC Target.RTM. and Simulink.RTM. 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)}.sub.d) is converted into a
desired joint space velocity ({dot over (q)}.sub.d) using a
resolved rates algorithm 406 implementing a kinematics model. These
velocities are then integrated at 408 to obtain desired joint
positions (q.sub.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.
[0077] 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
[0078] 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
[0079] 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 .kappa.. The actuation variables are .alpha..sub.1,
which denotes the angular position of the inner tube, .beta..sub.1
.di-elect cons.s (where s measures arc length), which is the
location where the inner tube is held by its carrier, and
.beta..sub.2 .di-elect cons.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.sub.1 and l.sub.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 .alpha..sub.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's tip as the robot deforms). Using
these definitions, the forward kinematics, g.sub.st, is given
by:
g st = [ R d 0 1 ] R = [ c .alpha. 1 - s .alpha. 1 c .gamma. s
.alpha. 1 s .gamma. s .alpha. 1 c .alpha. 1 c .gamma. - c .alpha. 1
s .gamma. 0 s .gamma. c .gamma. ] d = [ - r s .alpha. 1 ( c .gamma.
- 1 ) - r c .alpha. 1 ( c .gamma. - 1 ) l 2 + .beta. 2 + r s
.gamma. ] ( Eq . 1 ) ##EQU00001##
where .gamma.=.kappa.(.beta.1-.beta.2+l1-l2) and r=1/.kappa.. The
spatial Jacobian J.sub.s can be defined from the forward kinematics
as:
J s = [ ( .differential. g st .differential. .alpha. 1 g st - 1 ) V
( .differential. g st .differential. .beta. 1 g st - 1 ) V (
.differential. g st .differential. .beta. 2 g st - 1 ) V ] ( Eq . 2
) ##EQU00002##
[0080] The relationships between the spatial, body, and hybrid
Jacobians are defined as:
J s = A d g st J b J h = [ R 0 0 R ] J b ( Eq . 3 )
##EQU00003##
where Ad.sub.gst is the adjoint transformation, J.sub.h is the
hybrid Jacobian, and J.sub.b is the body Jacobian. Using Equations
1 and 3, the hybrid Jacobian can be shown to be:
J h = [ r c .alpha. 1 ( 1 - c .gamma. ) s .alpha. 1 s .gamma. - s
.alpha. 1 s .gamma. r s .alpha. 1 ( 1 - c .gamma. ) - s .gamma. c
.alpha. 1 s .gamma. c .alpha. 1 0 c .gamma. 1 - c .gamma. 0 .kappa.
c .alpha. 1 - .kappa. c .alpha. 1 0 .kappa. s .alpha. 1 - .kappa. s
.alpha. 1 1 0 0 ] ( Eq . 4 ) ##EQU00004##
[0081] Using this Jacobian, a singularity robust resolved rates
algorithm is implemented. The update step in this algorithm is
given as:
{dot over
(q)}=(J.sub.h.sup.TJ.sub.h+.lamda..sup.2I).sup.-1J.sub.h.sup.T{dot
over (x)} (Eq. 5)
where .lamda..sup.2 is given by:
.lamda. 2 = { 0 , .sigma. m .gtoreq. ( 1 - .sigma. m 2 ) .lamda. m
ax 2 , .sigma. m < ( Eq . 6 ) ##EQU00005##
where .epsilon. determines how close to singularity one wishes the
system to be before implementing the damping factor,
.lamda..sub.max is the maximum damping factor, and .sigma..sub.m is
the minimum singular value of J.sub.h, which indicates the degree
to which the Jacobian is conditioned.
Experimental Testing
[0082] 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.
[0083] 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.
[0084] 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.
[0085] 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.
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