Miniature in vivo Robots for Remote and Harsh Environments

Article (PDF Available)inIEEE Transactions on Information Technology in Biomedicine 12(1):66-75 · February 2008with42 Reads
DOI: 10.1109/TITB.2007.898017 · Source: PubMed
Abstract
Long-term human space exploration will require contingencies for emergency medical procedures including some capability to perform surgery. The ability to perform minimally invasive surgery (MIS) would be an important capability. The use of small incisions reduces surgical risk, but also eliminates the ability of the surgeon to view and touch the surgical environment directly. Robotic surgery, or telerobotic surgery, may provide emergency surgical care in remote or harsh environments such as space flight, or extremely forward environments such as battlefields. However, because current surgical robots are large and require extensive support personnel, their implementation has remained limited in forward environments, and they would be difficult, or impossible, to use in space flight or on battlefields. This paper presents experimental analysis of miniature fixed-base and mobile in vivo robots to support MIS surgery in remote and harsh environments. The objective is to develop wireless imaging and task-assisting robots that can be placed inside the abdominal cavity during surgery. Such robots will provide surgical task assistance and enable an on-site or remote surgeon to view the surgical environment from multiple angles. This approach is applicable to long-duration space flight, battlefield situations, and for traditional medical centers and other remote surgical locations.
66 IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE, VOL. 12, NO. 1, JANUARY 2008
Miniature in vivo Robots for Remote
and Harsh Environments
Mark E. Rentschler, Stephen R. Platt, Kyle Berg, Jason Dumpert, Dmitry Oleynikov, and Shane M. Farritor
Abstract—Long-term human space exploration will require con-
tingencies for emergency medical procedures including some capa-
bility to perform surgery. The ability to perform minimally invasive
surgery (MIS) would be an important capability. The use of small
incisions reduces surgical risk, but also eliminates the ability of
the surgeon to view and touch the surgical environment directly.
Robotic surgery, or telerobotic surgery, may provide emergency
surgical care in remote or harsh environments such as space flight,
or extremely forward environments such as battlefields. However,
because current surgical robots are large and require extensive
support personnel, their implementation has remained limited in
forward environments, and they would be difficult, or impossible,
to use in space flight or on battlefields. This paper presents experi-
mental analysis of miniature fixed-base and mobile in vivo robots to
support MIS surgery in remote and harsh environments. The ob-
jective is to develop wireless imaging and task-assisting robots that
can be placed inside the abdominal cavity during surgery. Such
robots will provide surgical task assistance and enable an on-site
or remote surgeon to view the surgical environment from multiple
angles. This approach is applicable to long-duration space flight,
battlefield situations, and for traditional medical centers and other
remote surgical locations.
Index Terms—Extreme and remote environments, in vivo,
robots, surgical, telementoring.
I. INTRODUCTION
R
OBOT-ASSISTED surgery continues to advance laparo-
scopic surgery. Robots such as the da Vinci surgical sys-
tem are currently being used to assist surgeons during minimally
invasive surgery (MIS). They have significant advantages over
manual laparoscopy, such as their ability to precisely control in-
struments, reduce hand tremor, and enable telesurgery. However,
these robots are very large, expensive, and are currently limited
to use in large surgical centers. A new area of surgical robotics
focuses on placing robots entirely inside the patient. These
in vivo robots currently lack some of the precise control provided
Manuscript received November 14, 2006; revised February 21, 2007.
M. E. Rentschler is with the University of Nebraska Medical Center, Omaha,
NE 68198 USA (e-mail: mrentschler@unmc.edu).
S. R. Platt and K. Berg are with the Department of Mechanical Engineer-
ing, University of Nebraska, Lincoln, NE 68588 USA (e-mail: srp@unlserve.
unl.edu; kyleaberg@gmail.com).
J. Dumpert is with the Department of Biomedical Engineering, University of
Nebraska, Lincoln, NE 68588 USA (e-mail: jdumper1@bigred.unl.edu).
D. Oleynikov is with the Department of Surgery, University of Nebraska
Medical Center, Omaha, NE 68198 USA, and also with the University of
Nebraska, Lincoln, NE 68588 USA (e-mail: doleynik@unmc.edu).
S. M. Farritor is with the Department of Mechanical Engineering, University
of Nebraska, Lincoln, NE 68588 USA, and also with the University of Nebraska
Medical Center, Omaha, NE 68198 USA (e-mail: sfarritor@unl.edu).
Color versions of one or more of the figures in this paper are available online
at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/TITB.2007.898017
by systems such as the da Vinci. However, they have been shown
to be useful in providing vision and task assistance [1], [2]. In
addition, in vivo robots are small, inexpensive, and easily trans-
ported, making it more likely that this technology can be more
widely adopted.
The Canadian Center for Minimal Access Surgery (CMAS)
has done much research in the area of telerobotic surgery
[3]. These efforts have included several missions with the
National Aeronautics and Space Administration (NASA) us-
ing the Aquarius underwater habitat to test telerobotic surgery
in remote and extreme environments. Aquarius, operated for
the National Oceanic and Atmospheric Administration (NOAA)
by the National Undersea Research Center (NURC) at the
University of North Carolina Wilmington (UNCW), is a sub-
mersible habitat that houses crews 20-m underwater for up
to several weeks off the coast of Key Largo, FL. The NASA
Extreme Environment Mission Operations (NEEMO) uses
Aquarius several times each year to provide analogous ex-
travehicular activity (EVA) and extended duration training for
Astronauts.
CMAS had teamed with the NASA during NEEMO 7,
October 2004, and NEEMO 9, April 2006 to perform surgical
training experiments. During NEEMO 9, in vivo robots from the
University of Nebraska were also tested and evaluated by the
crew. All four members of the crew performed simulated surgi-
cal tasks that included bowel inspection, stretch and dissect, and
appendectomy procedures. The surgical environment was r epli-
cated by placing synthetic materials inside an abdominal cavity
simulator, as shown in Fig. 1. The Aquanauts were trained be-
fore the mission to perform the bowel inspection and stretch
and dissect procedures using both a traditional laparoscope and
a fixed-base tilting camera robot. The crew received no training
for the appendectomy; this task required that the crew apply
the skills developed during the bowel inspection and stretch and
dissect procedures while being telementored through the appen-
dectomy by the University of Nebraska team, remotely located
in Omaha, NE.
This paper describes our current work to develop small and
easily transportable in vivo robots for use in extreme and remote
environments, such as long-duration space flight and battlefield
situations. The purpose of the miniature in vivo surgical robots
tests presented here was to evaluate the ease of use and the time
required to perform simple laparoscopic tasks utilizing differ-
ent vision systems (laparoscope, and in vivo camera robots).
The ability to use these robots as part of a telementoring system
to guide crew members through an unfamiliar surgical proce-
dure (appendectomy) in a remote harsh environment was also
assessed.
1089-7771/$25.00 © 2008 IEEE
RENTSCHLER et al.: MINIATURE in vivo ROBOTS FOR REMOTE AND HARSH ENVIRONMENTS 67
Fig. 1. (a) Abdominal cavity simulator equipment setup and (b) prepared for
task completion in the Aquarius habitat.
II. BACKGROUND
A. Robot-Assisted Surgery
The use of robots is currently recognized as a major driv-
ing force for advancing MIS [4]–[6]. However, current surgical
robots, such as the da Vinci surgical system made by Intuitive
Surgical, have several significant limitations. Although one re-
cent report concluded that robotic surgery can enhance dexterity
compared to traditional laparoscopy [7], most studies suggest
that current robotic systems offer little or no improvement over
standard laparoscopic instruments in the performance of basic
skills [8]–[10]. Current systems also remain constrained by lim-
ited sensory and mobility capabilities, and their high cost and
extensive support requirements make them unavailable to most
hospitals.
B. Other in vivo Robots
While much effort has focused on surgical robots in t he oper-
ating room, recent research also focuses on placing robots com-
pletely (or mostly) inside the patient. These in vivo robots help
to overcome the constraining limitations of working through
small incisions. The simplest such mechanisms have been en-
doscopes that include actuators that can turn the endoscope tip
after it enters the body [11], [12], leaving the power and control
equipment outside the body. Other scopes developed to explore
hollow cavities such as the colon or esophagus have included
locomotion systems based on “inch-worm” motion that use a se-
ries of grippers and extensors [13], [14], rolling tracks [15], or
rolling stents [16]. Another approach for exploring the gastroin-
testinal (GI) tract is swallowing an un-tethered camera pill. One
such commercially available device, called M2 A from Given
Imaging Ltd [17], [18], returns multiple (thousands) images as it
naturally moves through the GI tract. However, because the de-
vice is entirely passive, it cannot be directed to image a particular
location and the exact locations of the images are not known.
Combined with the very large volume of images, the use of this
device for diagnosis is difficult. Other work has focused on a
mobile robot to traverse the surface of a beating heart [19], [20].
This robot uses suction cups and has demonstrated successful
prehension, turning, locomotion, and dye injection in a porcine
(pig) model.
Most of the in vivo robots described earlier are designed
to function in very specific locations in the body. They are
all either nonmobile, or their mobility systems require narrow
hollow cavities, external power, or natural processes to function.
The in vivo robots used for this study have been developed for
use in the open environment of an insufflated abdomen during
laparoscopic surgery.
The in vivo robots presented here have CMOS camera im-
agers onboard t hat provide video feedback to the surgical team.
As low-cost CMOS technology continues to improve, so will
the video quality of these robots. Two recent studies were con-
ducted to determine efficacy of in vivo camera robots versus
a standard laparoscopic camera [21] using simulated surgical
tasks and color/resolution charts [22]. Results showed no sig-
nificant difference in performance for the two vision systems.
C. Telementoring and Telerobotic Surgery
The earliest use of telemedicine can be traced back to 1959,
when doctors used two-way video communication systems for
psychiatric consultation in Nebraska [23]. This innovative pi-
oneering project helped lead the way to present telementoring
and telesurgery possibilities. Surgical telementoring has now
been used for over a decade for both training young surgeons in
routine endoscopic surgery and advanced operations [24]. Such
telementoring has been shown to be as effective for develop-
ment of surgical skills as local mentoring when video and audio
quality are sufficient [25]. In fact, telemedicine in today’s world
of video conferencing includes education, training, consulting,
and mentoring. Assessment results of telemedicine in surgical
education and patient care show improved diagnostic potential
with accurate telediagnoses for surgical cases of 95% [26].
Early efforts at telerobotic surgery focused on developing the
robot kinematics and trajectory planning for telelaparoscopic
manipulation [27]. This included development of robotic exten-
ders that could be indirectly controlled by the surgeon through
a master arm. This master–slave robot system controls the
68 IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE, VOL. 12, NO. 1, JANUARY 2008
movement of the robot extender inside the abdominal cavity,
which is controlled indirectly by hand movements of the surgeon
on a telesurgical workstation. The other major research focus
was the development of a robust, fail-safe, and resilient real-time
communications system [28] and determination of acceptable
time delays that did not grossly affect surgical accuracy and dex-
terity [29]. These research efforts were combined in the early
part of the 21st century when the Zeus surgical system received
Food and Drug Administration (FDA) clearance and its use
in medical centers began. Early results showed that computer-
aided surgery (CAS) was safe and feasible, with patient recov-
ery times similar to those of conventional surgery [30]. Another
major advance in the CAS occurred in September 2001, when
the first example of transatlantic telesurgery was demonstrated
with a patient in Strasbourg and a surgeon in New York [31].
This showed that computer technology, robotics, fiber optics,
and surgical techniques had advanced sufficiently to overcome
the problems that had previously prevented successful long-
distance telesurgery, such as time delays, tremor filtering, and
insufficient visual feedback. Today, telerobotic surgery is rou-
tinely being used to provide high-quality laparoscopic surgical
services to patients in remote regions of Canada using a com-
mercially available network with 15 Mb/s of bandwidth [32].
To be successful, in vivo telerobots will need to be provided
with enough power, sufficient in vivo illumination, and large-
enough bandwidth to provide visual feedback to the remote
surgical team. The power requirement for the robots described
here is approximately 300 mA at 3 V. Commercially available
lithium oxide batteries have been successful in powering these
in vivo robots for up to 50 minutes. The Ultrabright LEDs used
with the camera robots each produce 10000 mcd, which has pro-
vided sufficient illumination. The CMOS imagers provide video
output in the National Television System Commission (NTSC)
format at 30 frames/s. We have used analog transmission thus
far to maintain a lower bandwidth requirement. However, mov-
ing to telerobotic surgery with in vivo robots will likely require
digital transmission. For digitally transmitted video quality com-
parable to video conferencing the necessary bandwidth range is
10–15 Mb/s.
Telerobotic surgery has generally been performed in tra-
ditional medical centers equipped with systems such as
da Vinci. However, the size and expense of this equipment lim-
its telesurgery’s presence in remote and harsh environments.
Providing inexpensive in vivo robots that can be remotely con-
trolled would provide telesurgical access and telementoring
in these remote locations (small rural hospitals, long-duration
space flight), and harsh environments (forward battlefield loca-
tions). In locations where telesurgical equipment exists, such
in vivo robots could be used to help augment the surgical view
and provide surgical assistance.
III. NASA E
XTREME ENGINEERING MISSION OPERATIONS
A. Habitat Description
Aquarius, shown in Fig. 2, is an underwater ocean labora-
tory located in the Florida Keys National Marine Sanctuary.
The 73.5-t laboratory (13 m × 6m× 5 m) is deployed three
Fig. 2. Aquarius habitat on the dock during maintenance (Image provided
courtesy of the NOAA’s Undersea Research Center at the University of North
Carolina, Wilmington).
and half miles offshore, at a depth of 20 m. Aquarius houses six
bunks, a restroom, and kitchen. Aquarius is an ambient pres-
sure habitat, with its interior atmospheric pressure equal to the
surrounding water pressure. Scientists live in Aquarius during
multiple weeklong missions using saturation diving to study and
explore the coastal ocean. Astronauts use Aquarius for extended
training for space flight. Aquarius is owned by the NOAA and is
operated by the NOAA Undersea Research Program’s (NURP)
Undersea Research Center at the University of North Carolina,
Wilmington.
B. Mission Description
The NEEMO 9 mission was a joint project involving the
CMAS at McMaster University, the University of Nebraska, the
U.S. Army Telemedicine and Advanced Technology Research
Center (TATRC), the National Space Biomedical Research
Institute (NSBRI), and the NASA. The mission built upon the
success of the NEEMO 7 mission and continued to evaluate new
medical diagnostic and therapeutic technologies to enhance the
delivery of state-of-the-art medical care in remote and harsh
environments. Another goal of the mission was to develop pro-
cedures and techniques for lunar exploration using remotely op-
erated vehicles, tracking systems, and navigation devices. The
Aquanaut crew included three NASA Astronauts trained in en-
gineering and general surgery, and one advanced laparoscopic
surgeon.
Each member of the four-person crew completed the tasks
onboard Aquarius, as shown in Fig. 3. These results helped
to validate in vivo camera robots as an effective alternative to
laparoscope use. The telementoring results demonstrated that
nonsurgeons having been trained with a specified skill set can
be telementored to build on that skill set and perform a more
complex laparoscopic procedure using in vivo robots.
IV. In vivo R
OBOTS
Much effort has been spent developing in vivo robots for
vision and task assistance during endoscopic surgery. The robots
function in the insufflated abdominal cavity, which is below the
RENTSCHLER et al.: MINIATURE in vivo ROBOTS FOR REMOTE AND HARSH ENVIRONMENTS 69
Fig. 3. Crew members completing miniature in vivo robot surgical tasks on-
board Aquarius (Images provided courtesy of the NASA).
diaphragm. Breathing does create a shallow rise in the surgical
field, but has not drastically affected the performance of the
robots. We continue to strive to reduce the size of our robots and
are currently developing most of our robots in the 12–15-mm
diameter range and 50–75-mm length range. The abdominal
cavity is generally 20 cm × 15 cm and is 8 cm in height when
fully insufflated. This is the “working” space for the robotic
team. The robots need to fit through a rigid trocar port (typical
sizes are 12–15 mm in diameter). Two broad classes of in vivo
robots have emerged: fixed base and mobile. The fixed-base
camera robots, similar to the tilt camera robot used during the
NEEMO 9 mission [Fig. 4(a)], can provide visual feedback to
the surgeon. These robots have adjustable-focus capability and
usually several DOFs that allow the view from the robot to
be panned and tilted. Several designs have incorporated LEDs.
Most of these devices have been tethered for power and video
feedback, although wireless versions have also been tested with
success. Several different attachment mechanisms have been
used for these robots. A spring-loaded foldable-tripod platform
was used for the NEEMO 9 test. This 1-DOF tilting robot is
15 mm in diameter (when the legs are abducted during insertion
and retraction) and 60-mm tall. A permanent magnet dc motor
is used to actuate the tilting mechanism and is controlled by
the crew member through a switch. The folding tripod base
allows the robot to be easily inserted into and removed from the
abdominal cavity through a standard trocar port.
This type of robot has previously been used successfully in an-
imal tests, during which the visual feedback from the robot was
used exclusively to perform a canine prostatectomy (prostate
removal) and nephrectomy (kidney removal) [33]. The tilting
camera robot shown in Fig. 4(a) was used by the NEEMO
9 crew during the bowel inspection and stretch and dissect
tasks, as discussed in Section V. Mobile in vivo robots were
developed to provide a mobile platform for visual feedback and
task assistance. These robots have two independent motors that
separately drive each wheel, which provides forward, reverse,
and turning capabilities for the two-wheeled mobile platform,
shown in Fig. 4(b). A wheel profile was developed such that
these robots can traverse abdominal organs without causing tis-
Fig. 4. (a) Tilting camera and (b) mobile camera in vivo robots used during
the NEEMO 9 mission.
sue damage [34]. The wheel profile used in the current work is
much different due to the nature of the experiments performed
during NEEMO 9. The mobile camera robot shown in Fig. 4(b)
is 110 mm in length and 20 mm in diameter. This robot is
controlled by the crew member using a joystick. Both of the
NEEMO 9 robots also have onboard adjustable-focus cameras
that provide visual feedback. The focusing mechanism is driven
by a motor and a series of gears that change the position of
the imager relative to the lens. A mobile camera robot, similar
to the one shown in Fig. 4(b) has been used to provide exclu-
sive visual feedback to a surgeon during a porcine cholecystec-
tomy (gallbladder removal) [1]. A mobile camera and biopsy
robot were also developed and used successfully to biopsy por-
tions of hepatic (liver) tissue during an animal surgery [2]. Such
robots have also recently been used to demonstrate the feasibil-
ity of performing natural orifice transgastric endoscopic surgery
(NOTES), wherein a robot is introduced to the abdominal cavity
through an incision in the gastric cavity instead of the traditional
approach of keyhole surgery with trocars placed in the abdomi-
nal wall [35]. The mobile camera robot shown in Fig. 4(b) was
used by the NEEMO 9 crew to provide visual feedback during
the appendectomy procedure, as discussed in Section V.
V. NEEMO 9 T
ASKS
The crew performed the surgical tasks using the abdomi-
nal cavity simulator shown in Fig. 1. During the tasks, the
crew manipulated the tissue specimens using laparoscopic tools
70 IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE, VOL. 12, NO. 1, JANUARY 2008
Fig. 5. (a) Overview of the robot and rope position setup for the rope passing
task and (b) the abdominal cavity simulator camera view of the rope passing
task using the laparoscope’s video feedback.
inserted through the trocar holes in the cover of the simulator.
The crew observed their performance by watching the video
feedback from the in vivo robots or laparoscope on a computer
screen, as shown in Fig. 3. The same screen was used for all
video feedback and the position of the computer screen was
unchanged for each set of tasks.
A. Bowel Inspection/Rope Passing
The bowel inspection task involved passing a rope with
colored segments from laparoscopic grasper to laparoscopic
grasper while only contacting the colored portions, spaced ev-
ery 5 cm. This task replicates the surgical task used to inspect
very long sections of bowel. The rope was passed back and
forth five times using the handheld laparoscopic graspers. Each
crew member performed this task one time using a 0-degree
laparoscope and one time using the tilting camera robot for vi-
sual feedback. The rope was initially positioned as shown in
Fig. 5(a). The tilting camera robot and light source were posi-
tioned over fixed location markings on the simulator box bottom,
as shown in Fig. 5(a), and the laparoscope was positioned above
the tilting camera robot, as shown in Fig. 5(b). These two po-
sitions are representative of the nominal positions used during
Fig. 6. (a) Overview of the robot and specimen setup for the stretch and
dissect task and (b) the abdominal cavity simulator camera view of the stretch
and dissect task using the laparoscope’s video feedback.
laparoscopic surgery. The tilting camera r obot used a separate
light source and the imager settings were adjusted to match this
illumination. The laparoscope used its integrated xenon light
source for illumination.
B. Stretch and Dissect
The stretch and dissect task involved grasping synthetic strips
of tissue and cutting down a marked line on the tissue using
laparoscopic tools. This task simulates surgical laparoscopic
dissection. Each crew member also performed this task one
time using the laparoscope and one time using the tilt camera
robot for visual feedback. The same lighting and positioning of
tools, robots, and light sources were used for the stretch and
dissect and the bowel passing tasks.
Two sets of tissue strips were placed, as shown in Fig. 6(a).
One set of five strips was placed on an incline so that the crew
member would need to pull the tissue to the right to cut along the
marked location. The other set of five strips was placed along
the back wall of the simulator so that the crew member would
need to pull the tissue down to cut along the marked location.
RENTSCHLER et al.: MINIATURE in vivo ROBOTS FOR REMOTE AND HARSH ENVIRONMENTS 71
Fig. 7. (a) Overview of the robot and appendix position setup for the ap-
pendectomy task and (b) the abdominal cavity simulator camera view of the
appendectomy task using the mobile robot’s video feedback.
C. Appendectomy
This task was completed without specific previous training
to evaluate whether a skill set can be built upon and the crew
members could be telementored through an unfamiliar surgical
procedure using the in vivo robots. The crew had been trained
beforehand on use of the surgical tools, including control of the
mobile camera robot. Immediately prior to starting this task,
each crew member watched a short 30-s video describing the
appendectomy procedure. The crew member was then telemen-
tored, using video conferencing software, about the nuances of
the procedure and how best to complete the task. The mobile
camera robot and light source were positioned over markings
on the simulator box bottom, as shown in Fig. 7(a). Finally, the
crew member performed the task while being telementored. The
appendectomy procedure involved driving the mobile camera
robot toward an appendix (as shown in Fig. 7) that was similar
in size and anatomy to a patient, using only video feedback
from the robot. After positioning the mobile robot to optimize
the view, the crew member performed the appendectomy by
stapling, dissecting, and removing the appendix.
The most common complication associated with an appen-
dectomy is infection of the wound (surgical incision). The sec-
Fig. 8. (a) View from the tilting camera robot and (b) laparoscope during the
rope passing task.
ond most common complication is perforation of the appendix
leading to abdominal infection. Both complications are usually
treated with antibiotics. For future studies, we may create a sim-
ulation appendix with fluid inside the appendix to examine if
the procedure can be completed while preventing any leakage.
VI. E
XPERIMENTAL RESULTS
The video recorded during each task for each crew member
was reviewed after the mission. Raw data were then compiled
using this video to evaluate performance metrics.
A. Rope Passing
The rope passing task was individually and successfully com-
pleted by each crew member during the mission using visual
feedback from the tilting camera robot [Fig. 8(a)] and the la-
paroscope [Fig. 8(b)]. This task was timed and accuracy was
determined by postprocessing the video data including only the
time required to complete the task and excluding setup time.
For the rope passing task, the metrics used were time, num-
ber of hits, number of misses, and number of grasps. Hits were
defined by the number of times the crew member correctly
grasped the colored rope segments, misses were defined as
72 IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE, VOL. 12, NO. 1, JANUARY 2008
TABLE I
R
OPE PASSING DATA ANALYSIS
Fig. 9. Time-difference plots (tilt robot time minus laparoscope time) for each
crew member for both the bowel inspection task and the stretch and dissect task.
the number of times they grasped the rope between the col-
ored segments, and the number of grasps was the sum of hits
and misses. Perfect completion of the task would be to touch
only the colored segments while passing the rope back and
forth five times, as previously described. This would result in
100 hits and no misses. During completion of this task, each
crew member touched the rope (miss) and/or grabbed an indi-
vidual colored segment (hit) more than one time each during
the pass. Therefore, the results include performances where the
number of hits exceeds 100.
Paired t tests were computed for each crew member, with
the pairs of data corresponding to the visual feedback system
used, either laparoscope or tilting camera robot. These data are
summarized in Table I, where df is the degrees of freedom
(N 1), t is the t statistic, p is the 2-sided significance level,
and µ is the group mean. Degrees of freedom (df ), as used in
statistical analysis, is a measure of the number of independent
pieces of information on which the precision of a parameter
estimate is based. In this case, df =4 1 because we are using
the data from the four crew members to calculate a mean for
each metric. There was no significant difference (p>0.05)
between the two vision systems for each of the four metrics.
The plots shown in Fig. 9 summarize the differences in time
required for each crew member to complete the bowel inspec-
tion and stretch and dissect tasks using each of the two vision
systems. All but one crew member completed each of the two
tasks more quickly using video feedback from the tilt robot com-
pared to that from the laparoscope. The cause of crew member
D’s apparently anomalous result can only be subject to spec-
Fig. 10. (a) View from the tilting camera robot and (b) laparoscope during the
stretch and dissect task.
ulation. However, if the timed data are analyzed without crew
member D(N =3,df=2),thet statistic changes significantly
(t = 6.29) and the p value decreases (p =0.024), which in-
dicates a significant difference. These results suggest that video
feedback from the tilting camera robot is at least as good as that
from the laparoscope for this task.
B. Stretch and Dissect
The stretch and dissect task was individually and successfully
completed by each member of the crew during the mission using
visual feedback from the tilting camera robot [Fig. 10(a)] and the
laparoscope [Fig. 10(b)]. This task was timed and accuracy was
determined by posttest measurements of the tissue specimens.
The metrics used for the stretch and dissect task were distance
of cut, angle of cut, and time. The distance metric was defined
to be the distance in millimeters between the indicated cutting
position mark on the specimen and the actual cut position. The
angle metric was the angular error between the actual cut and
the indicated mark on each specimen, measured in degrees. The
time metric was task duration in seconds. The absolute value
of the error was used for both the distance and angle metrics.
Paired t tests were again used to analyze the data, and the results
are summarized in Table II.
RENTSCHLER et al.: MINIATURE in vivo ROBOTS FOR REMOTE AND HARSH ENVIRONMENTS 73
TABLE II
S
TRETCH AND DISSECT DATA ANALYSIS
Fig. 11. (a) Distant v iew and (b) close-up view from the mobile camera robot
during the appendectomy.
There is no significant difference (p>0.05) between the
two vision systems when comparing the angle and distance
metrics. However, the time metric shows a significant difference
(p<0.05), with the mean time using the tilt robot 40.75 s less
than the mean time for the laparoscope.
C. Appendectomy
Each member of the crew successfully completed the appen-
dectomy task. Several views from the mobile camera robot are
shown in Fig. 11. These results help demonstrate that the crew
can be trained on a specific skill set and that through telementor-
ing they can build upon this skill set to complete more complex
tasks.
TABLE III
S
URVEY RESULTS
D. Survey Results
After completing the surgical tasks, each crew member was
asked a series of survey questions related to depth perception,
lighting, video feedback, camera control, and overall function-
ality of the camera robots and the laparoscope. Crew members
answered the questions on a scale from 1 to 5, with 5 being the
best. Paired t tests were used to analyze these data. The results
are summarized in Table III.
In all categories, except for one, there was no significant
difference (p>0.05) in scores between the two systems. The
survey results indicate that better lighting would be helpful when
using t he in vivo camera robots. To help augment this, current
work has focused on adjusting onboard camera settings, such as
brightness, hue, saturation, and color to better fit the low-lighting
conditions during surgery in the abdominal cavity. Analysis of
the survey answers indicates that the use of telementoring with
the use of surgical robots could be beneficial.
E. Results Summary
The combined results from these tests show that there was
no significant difference between the two vision systems when
comparing task accuracy. However, there was a significant de-
crease in the time required to complete the tasks when using the
in vivo camera robots. These results show that video feedback
from the tilting camera robot is at least as good as, and per-
haps superior to, that from the laparoscope for these tasks. The
telementoring task results help demonstrate that individuals can
be trained on a basic skill set and that through telementoring
they can build upon this skill set to complete more complex
procedures.
VII. F
UTURE DIRECTIONS
In vivo robots for endoscopic surgery have the potential to be
used in traditional medical centers, remote surgical locations,
extreme environments such as battlefields, and harsh environ-
ments such as long-duration space flight. The goal of the current
research is to provide improved visual feedback to the surgeon
through multiple in vivo video systems, provide in vivo tissue
manipulation and task assistance, and reduce patient trauma by
requiring only a single incision through which multiple robots
could be inserted. Because these devices are very small and
portable, their use in remote, harsh, and extreme environments
will provide surgical assistance otherwise not possible. As the
74 IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE, VOL. 12, NO. 1, JANUARY 2008
technology develops, improvements may include telecontrol,
task assistance, and some autonomy.
VIII. S
UMMARY AND CONCLUSION
This paper presents the results from the NEEMO 9 mission
during which in vivo robots from the University of Nebraska
were tested and evaluated by a four-member crew comprised of
three NASA Astronauts and one surgeon. The crew performed
simulated surgical tasks that included bowel inspection, stretch
and dissect, and appendectomy procedures. The surgical envi-
ronment was replicated by placing synthetic materials inside
an abdominal cavity simulator, and the procedures were per-
formed using standard laparoscopic tools in combination with
video feedback from a traditional laparoscope or in vivo cam-
era robots. The Aquanauts were trained before the mission to
perform the bowel inspection and the stretch and dissect tasks.
The crew was not pretrained to perform the appendectomy. The
appendectomy task required the crew to use the in vivo camera
robots and the skills developed in the other two tasks while being
telementored via videoconferencing through the appendectomy
by the University of Nebraska team at Omaha.
Although the sample size is small (N =4), for both the rope
passing and stretch and dissect tasks, there was no significant
statistical difference in task accuracy between the two visual
feedback systems. However, there is a significant decrease in
the times required to complete the tasks when using the tilting
camera robot. The appendectomy results show that the crew
could build upon a core set of skills to perform a new procedure
using in vivo robots and telementoring. The combined results
from these tests suggest that the use of miniature surgical robots
could be used in place of standard laparoscopic surgical equip-
ment without loss of performance. These results show that video
feedback from the in vivo camera robots is at least as good as that
from the laparoscope for these tasks. The use of these robots can
potentially reduce patient trauma in traditional medical centers,
while the size of the robots makes them ideal for transportation
to and use in remote or harsh environments.
A
CKNOWLEDGMENT
The authors would like to thank the CMAS for leading this
project and the NURC for the opportunity to conduct this excit-
ing research. We would also like to thank everyone who helped
topside with NEEMO 9, with a special thanks to the NEEMO 9
crew including the engineering support team.
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Mark E. Rentschler received the B.S. degree
in mechanical engineering from the University of
Nebraska, Lincoln, in 2001, the M.S. degree in me-
chanical engineering from the Massachusetts Insti-
tute of Technology, Cambridge, in 2003, and the
Ph.D. degree in biomedical engineering from the Uni-
versity of Nebraska in 2006.
In 2003, he was a National Defense Science and
Engineering Graduate Fellow at the Massachusetts
Institute of Technology. He is currently a Post-
doctoral Research Associate at the University of
Nebraska Medical Center, Omaha. His current research interests include the
areas of surgical robotics, mechanical design, tissue mechanics, and medical
mechatronics.
Stephen R. Platt received the B.A. degree in
physics and astronomy from Williams C ollege,
Williamstown, MA, in 1983, the M.S. and Ph.D.
degrees in astronomy and astrophysics from the Uni-
versity of Chicago, Chicago, IL, in 1991, and the M.S.
degree in mechanical engineering from the Univer-
sity of Nebraska, Lincoln, in 2003.
He is currently a Research Assistant Professor
in the Department of Mechanical Engineering, Uni-
versity of Nebraska. His current research interests
include biomedical sensors, surgical robotics, and
millimeter-wave detector systems for observational astrophysics applications.
Kyle Berg received the B.S. degree in mechanical
engineering in 2005 from the University of Nebraska,
Lincoln, where he is currently working toward the
Masters degree in mechanical engineering and is a
Graduate Research Assistant.
His current research interests include abdominal
wall modeling and surgical robotics.
Jason Dumpert received the B.S. and M.S. de-
grees in electrical engineering in 2001 and 2004,
respectively, both from the University of Nebraska,
Lincoln, where he is currently working toward the
Ph.D. degree in biomedical engineering and is a
Graduate Research Assistant.
His current research interests include mobile
robotics and surgical robotics.
Dmitry Oleynikov received the M.D. degree from
Albert Einstein School of Medicine at Yeshiva
University, NY.
He is Board Certified in General Surgery and
is an Associate Professor and Director of the Edu-
cation and Training Center for Minimally Invasive
and Computer-Assisted Surgery at the University of
Nebraska Medical Center, Omaha. He is also an Ad-
junct Assistant Professor of Engineering at the Uni-
versity of Nebraska, Lincoln.
He completed the surgical residency at the
University of Utah Medical Center, Salt Lake City, in 2000. After residency, he
served as Acting Instructor and Senior Fellow at the Center for Videoendoscopic
Surgery, Department of Surgery, University of Washington School of Medicine,
Seattle. His current research interests include surgical simulation and robotics.
Shane M. Farritor received the B.S. degree from
the University of Nebraska, Lincoln, in 1992, and
the M.S. and Ph.D. degrees in mechanical engineer-
ing from the Massachusetts Institute of Technology,
Cambridge, in 1998.
He is currently an Associate Professor of
Mechanical Engineering at the University of
Nebraska, and holds courtesy appointments in both
the Department of Surgery and the Department of
Orthopedic Surgery at the University of Nebraska
Medical Center, Omaha. His current research inter-
ests include space robotics, surgical robotics, biomedical sensors, and robotics
for highway safety.
Dr. Farritor serves as the Chairman of the American Institute of Aero-
nautics and Astronautics (AIAA) Space Robotics and Automation Technical
Committee.
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