robotic systems used in surgery

7/28/2019 Robotic Systems used in surgery.

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Technical University of Cluj-NapocaFaculty of Machine BuildingSpecialization of Industrial Robots

Workspaces and

singularities of parallelrobots used in surgery

Student:

Slyom Csaba,

Group 1542 R.I.e


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MSRI Project Slyom Csaba

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I. Definitions

1. Minimally Invasive Surgery

The invasiveness of surgical procedures can be classified as follows:non-

invasive procedures,min imal ly invasive procedur es, andinvasive procedures(the

latter of which may also be calledopen surgery).

A minimal ly invasive procedure(MIP) is any procedure (surgical or

otherwise) that is less invasive than open surgery used for the same purpose. A

minimally invasive procedure typically involves use of arthroscopic (for joints and the

spine) or laparoscopic devices and remote-control manipulation of instruments with

indirect observation of the surgical field through an endoscope or large scale display

panel, and is carried out through the skin or through a body cavity or anatomicalopening.

By use of a MIP, the scarring will be minimal, able to be taken care of easily.

This usually results in less infection, a quicker recovery time and shorter hospital

stays, or allows outpatient treatment. The term was coined by John EA Wickham in

1984, who wrote of it in British Medical Journalin 19871. When there is minimal

damage of biological tissues at the point of entrance of instrument(s), the procedure

is called minimally invasive.

For the above stated reasons, minimally invasive surgery is becomingincreasingly used in all fields of surgery, to greatly enhance the effectiveness of the

treatments by reducing recovery time and infection risks, thus also reducing costs

associated with post-surgical care facilities. The introduction of robotic systems into

this area is promising, because the capabilities and advantages of robotic systems

play well into the advantages of minimally invasive surgery (reducing costs,

increasing precision, speed and effectiveness). Most such equipment is used for

minimally invasive procedures, but robotic surgery is not confined to this field, open

surgery also benefits from the use of robots.

1Wickham JE' (1987-12-19). "The new surgery". Br Med J295: 15811582.

doi:10.1136/bmj.295.6613.1581.
http://en.wikipedia.org/wiki/Digital_object_identifierhttp://dx.doi.org/10.1136%2Fbmj.295.6613.1581http://dx.doi.org/10.1136%2Fbmj.295.6613.1581http://dx.doi.org/10.1136%2Fbmj.295.6613.1581http://dx.doi.org/10.1136%2Fbmj.295.6613.1581http://en.wikipedia.org/wiki/Digital_object_identifier


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2. Robotic Surgery

Robotic surgery, computer-assisted surgery, and robotically-assisted surgery

are terms for technological developments that use robotic systems to aid in surgical

procedures. Robotically-assisted surgery was developed to overcome the limitations

of minimally-invasive surgery and to enhance the capabilities of surgeons performing

open surgery.

In the case of robotically-assisted minimally-invasive surgery, instead of

directly moving the instruments, the surgeon uses one of five methods to control the

instruments; either a direct telemanipulator or through computer control. A

telemanipulator is a remote manipulator that allows the surgeon to perform the

normal movements associated with the surgery whilst the robotic arms carry out

those movements using end-effectors and manipulators to perform the actual surgeryon the patient. In computer-controlled systems the surgeon uses a computer to

control the robotic arms and its end-effectors, though these systems can also still use

telemanipulators for their input. One advantage of using the computerized method is

that the surgeon does not have to be present, but can be anywhere in the world,

leading to the possibility for remote surgery.

In the case of enhanced open surgery, autonomous instruments (in familiar

configurations) replace traditional steel tools, performing certain actions (such as rib

spreading) with much smoother, feedback-controlled motions than could be achieved

by a human hand. The main object of such smart instruments is to reduce oreliminate the tissue trauma traditionally associated with open surgery without

requiring more than a few minutes' training on the part of surgeons. This approach

seeks to improve open surgeries, particularly cardio-thoracic, that have so far not

benefited from minimally-invasive techniques.2

2Definition retrieved fromhttp://en.wikipedia.org/wiki/[email protected].
http://en.wikipedia.org/wiki/Robotic_surgeryhttp://en.wikipedia.org/wiki/Robotic_surgeryhttp://en.wikipedia.org/wiki/Robotic_surgeryhttp://en.wikipedia.org/wiki/Robotic_surgery


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II. Robotic Systems Utilized in Surgery

The first robotic surgery was performed in 1985, using the PUMA 200 model.

From this point onward, robotic surgery gained rapidly in popularity to the point whereseveral companies began selling stand-alone robotic systems on a large scale to

numerous hospitals, including the ZEUS Robotic Surgical System (discontinued in

2003) and the da Vinci Surgical System (currently the most popular robotic surgical

system in the world, widely utilized in the USA).

1. The da Vinci Surgical System

Fig.2.1.1 The da Vinci Surgical Systems main structure,

without the teleoperation equipment

The da Vinci Surgical System is a robotic surgical system made by theAmerican company Intuitive Surgical. It is designed to facilitate complex surgery

using a minimally invasive approach, and is controlled by a surgeon from a console.

The system is commonly used for prostatectomies, and increasingly for cardiac valve

repair and gynecologic surgical procedures. According to the manufacturer, the da

Vinci System is called da Vinci in part because Leonardo da Vinci invented the first

robot, as discovered by Mario Taddei. Da Vinci also used anatomical accuracy and

three-dimensional details in his works.

Da Vinci robots operate in several thousand hospitals worldwide, with an

estimated 200,000 surgeries conducted in 2012, most commonly for hysterectomiesand prostate removals. By January 2013, more than 2,000 units had been sold


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worldwide. The current version of the robot costs on average US$2.5 million, in

addition to several hundred thousand dollars of annual maintenance fees.

The da Vinci System consists of a surgeons console that is typically in the

same room as the patient, and a patient-side cart with four interactive robotic arms

controlled from the console. Three of the arms are for tools that hold objects, and canalso act as scalpels, scissors, bovies, or unipolar or bipolar electro cautery

instruments. The fourth arm carries an endoscopic camera with two lenses that gives

the surgeon full stereoscopic vision from the console. The surgeon sits at the console

and looks through two eye holes at a 3D image of the procedure, while maneuvering

the arms with two foot pedals and two hand controllers. The da Vinci System scales,

filters and translates the surgeons hand movements into more precise micro-

movements of the instruments, which operate through small incisions in the body.

To perform a surgical procedure, the surgeon must first use the systems

weight to judge how hard it should work. Then he/she uses the consoles master

controls to maneuver the patient-side carts three or four robotic arms (depending on

the model). The instruments jointed-wrist design exceeds the natural range of motion

of the human hand; motion scaling and tremor reduction further interpret and refine

the surgeons hand movements. The da Vinci System always requires a human

operator, and incorporates multiple redundant safety features designed to minimize

opportunities for human error when compared with traditional approaches.

Fig.2.1.2. The da Vinci Surgical System in operation,

with the surgeons console on the left

The da Vinci System has been designed to improve upon conventionallaparoscopy, in which the surgeon operates while standing, using hand-held, long-


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shafted instruments, which have no wrists. With conventional laparoscopy, the

surgeon must look up and away from the instruments, to a nearby 2D video monitor

to see an image of the target anatomy. The surgeon must also rely on his/her patient-

side assistant to position the camera correctly. In contrast, the da Vinci Systems

ergonomic design allows the surgeon to operate from a seated position at the

console, with eyes and hands positioned in line with the instruments. To move the

instruments or to reposition the camera, the surgeon simply moves his/her hands.

By providing surgeons with superior visualization, enhanced dexterity, greater

precision and ergonomic comfort, the da Vinci Surgical System makes it possible for

more surgeons to perform minimally invasive procedures involving complex

dissection or reconstruction. For the patient, a da Vinci procedure can offer all the

potential benefits of a minimally invasive procedure, including less pain, less blood

loss and less need for blood transfusions. Moreover, the da Vinci System can enable

a shorter hospital stay, a quicker recovery and faster return to normal daily activities.


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During the surgery, the surgeon sits at the ZEUS console to control the arms.

This can also lessen fatigue, because the surgeon is sitting down during the long

operation rather than leaning over the patient.

The ZEUS is also able to perform remote surgery. Because the surgeon is

simply controlling the robotic arms, the surgeon can sit at a ZEUS console remotefrom where the surgery is actually taking place, and still be able to perform the

surgery.


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3. Parallel Robots in Minimally Invasive Surgery

A parallel manipulator is a mechanical system that uses several computer-

controlled serial chains to support a single platform, or end-effector. Perhaps, the

best known parallel manipulator is formed from six linear actuators that support a

movable base for devices such as flight simulators. This device is called a Stewart

platform or the Gough-Stewart platform in recognition of the engineers who first

designed and used them.

Also known as parallel robots, these systems are articulated robots that use

similar mechanisms for the movement of either the robot on its base, or one or more

manipulator arms. Their parallel distinction, as opposed to a serial manipulator, is

that the end effector (or hand) of this linkage (or arm) is connected to its base by a

number of (usually three or six) separate and independent linkages working inparallel. Parallel is used here in the topological sense, rather than the geometrical;

these linkages act together, but it is not implied that they are aligned as parallel lines.

A parallel manipulator is designed so that each chain is usually short, simple

and can thus be rigid against unwanted movement, compared to a serial manipulator.

Errors in one chains positioning are averaged in conjunction with the others,

rather than being cumulative. Each actuator must still move within its own degree of

freedom, as for a serial robot; however in the parallel robot the off-axis flexibility of a

joint is also constrained by the effect of the other chains. It is this closed-loopstiffness that makes the overall parallel manipulator stiff relative to its components,

unlike the serial chain that becomes progressively less rigid with more components.

This mutual stiffening also permits simple construction: Stewart platform

hexapods chains use prismatic joint linear actuators between any-axis universal ball

joints. The ball joints are passive: simply free to move, without actuators or brakes;

their position is constrained solely by the other chains.

Delta robots have base-mounted rotary actuators that move a light, stiff,

parallelogram arm. The effector is mounted between the tips of three of these arms

and again, it may be mounted with simple ball-joints. Static representation of a

parallel robot is often akin to that of a pin-jointed truss: the links and their actuators

feel only tension or compression, without any bending or torque, which again reduces

the effects of any flexibility to off-axis forces.

A further advantage of the parallel manipulator is that the heavy actuators may

often be centrally mounted on a single base platform, the movement of the arm

taking place through struts and joints alone. This reduction in mass along the arm

permits a lighter arm construction, thus lighter actuators and faster movements. This

centralization of mass also reduces the robots overall moment of inertia, which maybe an advantage for a mobile or walking robot.


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All these features result in manipulators with a wide range of motion capability.

As their speed of action is often constrained by their rigidity rather than sheer power,

they can be fast-acting, in comparison to serial manipulators.

One of the drawbacks of the parallel robots refer to the existence of singularity

points and a smaller workspace, their analysis being an important step in thedevelopment of a robot. Singularity of parallel manipulators has been thoroughly

investigated, using different methods, mainly including: the rank and the condition

number of the Jacobian matrix of the loop closure equations, the screw theory and

the augmented Jacobian matrix. Pastorelli and Battezzato use a dimensionless

geometric approach to determine the singularity loci in Ref. Singularities are

important issues concerning parallel robots. In order to identify and avoid them go as

to ensure the stability of the system and kinematic accuracy. Physically, these

singular positions determine an instantaneous change in the system number of

degrees of freedom, thus leading to the degradation of its natural stiffness.


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3.1. SurgiScope

Fig. 2.3.1.1 The SurgiScope robotic system, with the

remote operation module in the lower right corner

The SurgiScope is a ceiling mounted robotized tool-holder device which

belongs to the surgical neuronavigation products family. It is a 7 degrees of freedom

microscope. Depth electrode targeting and trajectory determination can be performed

on the SurgiScope workstation, given the electrode entry site coordinated, the

targeted location of the subdural electrodes and the planned craniotomy.

This system is operated under the complete control of the surgeon and

operating team. Specifically designed for microscope-assisted neurosurgical

applications, it supports all types of interventions and the most common positioning.

The "ScopePlan by ISIS" software, developed according to stereotaxic

principles, allows users to quickly and easily define an operating strategy while

gaining virtual access to their zone of interest. The connection to the tool holder is

established at the start of surgery, and allows the operator take advantage of all tools

for identification, location, and visualization within the zone.


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Equipped with an instrument holder kit the SurgiScope can hold and position

precisely endoscopic tools or biopsy needles. A surgeon no longer needs to lift the

microscope eyepiece to see surgical display screens. The SurgiScopes image

injection module will display data directly within the surgeons field of view.


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3.2. The Three Degrees of Freedom PARAMIS Robot

This is a robot developed in Romania for surgical instrument positioning. It

was designed to have small sizes, to present minimal damage to patient, to be rigid

and stable having 3 DOF in order to cover the necessary surgical field, 1 translation

and two rotations.

The 3 DOF structure consists of three actuated joints (2 prismatic, 1

rotational). The passive joints are two cylindrical joints, one prismatic joint and one

Cardan joint. The particularity of this motion is the fact that the endoscope will move

around a fixed point in space, which is the entrance point of the trocar in the

abdominal wall of the patient.

For the geometric modeling a second mobile coordinate system is needed (x,

y, z) shown in Fig2.3.2.1., having the origin in point A, the point where endoscope isfixed in the passive Cardan joint of the robot.

Fig.2.3.2.1 Kinematics scheme of the robot


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Fig.2.3.2.2. Angles of the passive Cardan joint

Geometric characteristics of the parallel robot are defined by b, h, d, the

coordinate of point B, all these values are considered as know.

It is noted with h1 the portion of the endoscope that is inside the patient abdomen

e=h-h1the portion of the endoscope that is outside the patients abdomen

For geometric modeling we consider the following equations system, whichdefines the relation between the coordinates of point A and the joint coordinates: q1,

q2, q3.

For the analytic generation of the workspace of the PARAMIS robot, it is

needed to find some correlation between the possible values from the joints and the

end effectors coordinates, in such way that the end effector still remains in the

workspace.

In order to determine the points that make up the workspace, we suppose that

beside the geometric parameters the coordinates of point B is also known.

We determine an extreme position for q1, after which inside of 3 combined

repetitive cycles we generate all the possible combination of values between q1, q2,

q3,

The next step is to check if the generated combination fulfills the following conditions:

the relative angle between the laparoscope and the vertical axis is less than

60 degree;

AB < 50 mm;

the distance between the translational couples is greater than 50mm;


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Workspace generation code using the direct geometric model, written in MathLAB for

the possibility of visualizing the resulting workspaces:

function w=workspace_PARAMIS()

b=385;

h=263;d=685;

XB=1001;

YB=0;

ZB=281;

hilf=1;

for i=0:5:300

q(1)=340+i;

for j=0:5:600

q(2)=345+j;

for k=-10:1:10q(3)=k*pi/180;

rA=b+sqrt(d^2-(q(2)-q(1))^2);

XA=rA*cos(q(3));

YA=rA*sin(q(3));

ZA=q(1);

if (XA==XB) && (YA==YB)

XE=XB;

YE=YB;

ZE=ZA-h;

elseee=sqrt((XA-XB)^2+(YA-YB)^2+(ZA-ZB)^2);

fi=atan2(sqrt(1-((ZA-ZB)/ee)^2),(ZA-ZB)/ee);

teta=atan2((YA-YB),(XA-XB));

XE=XA-h*sin(fi)*cos(teta);

YE=YA-h*sin(fi)*sin(teta);

ZE=ZA-h*cos(fi);

end

h1=sqrt((XB-XE)^2+(YB-YE)^2+(ZB-ZE)^2);

if (acos((ZB-ZE)/h1)50)&&(q(2)-q(1)>20)&&(ZAZB>50)

X(hilf)=XE;Y(hilf)=YE;

Z(hilf)=ZE;

hilf=hilf+1;

end;

end;

end;

end;

X(hilf-1)=XB;

Y(hilf-1)=YB;

Z(hilf-1)=ZB;

i=1:hilf-1;


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scatter3(X(i),Y(i),Z(i),filled);

colormap hot

grid on

axis square

view(-45,45)

% box on% Determine the minimum and the maximum x and y values:

i=1:hilf-1;

x=X(i);

y=Y(i);

z=Z(i);

xmin = min(x); ymin = min(y);

xmax = max(x); ymax = max(y);

% Define the resolution of the grid:

xres=200;

yres=200;% Define the range and spacing of the x- and y-coordinates,

% and then fit them into X and Y

xv = linspace(xmin, xmax, xres);

yv = linspace(ymin, ymax, yres);

[Xinterp,Yinterp] = meshgrid(xv,yv);

% Calculate Z in the X-Y interpolation space, which is an

% evenly spaced grid:

Zinterp = griddata(x,y,z,Xinterp,Yinterp);

% Generate the mesh plot (CONTOUR can also be used):

figuremeshc(Xinterp,Yinterp,Zinterp);

colormap hot

xlabel X; ylabel Y; zlabel Z;

figure

surf(Xinterp,Yinterp,Zinterp);

colormap hot

xlabel X; ylabel Y; zlabel Z;

hilf

figure

i=1:hilf-1;x=X(i);

y=Y(i);

z=Z(i);

XX=[x; y; z];

[K,v]=convhulln(XX);

trisurf(K,XX(:,1),XX(:,2),XX(:,3))


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Fig.2.3.2.3. Example workspace using variables of 1mm and 1 degree for the translational and

rotational joints respectively.

Fig.2.3.2.4. Singularity points reported to the fixed point B


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Fig.2.3.2.4 Kinematic scheme

One of the drawbacks of the parallel robots refer to the existence of singularitypoints and a smaller workspace, their analysis being an important step in the

development of a robot. Singularity of parallel manipulators has been thoroughly

investigated, using different methods, mainly including: the rank and the condition

number of the Jacobian matrix of the loop closure equations the screw theory and the

augmented Jacobian matrix Pastorelli and Battezzato use a dimensionless geometric

approach to determine the singularity loci in the reference system.

Fig.2.3.2.5 Parallel model

Singularities are important issues concerning parallel robots. In order to

identify and avoid them go as to ensure the stability of the system and kinematic

accuracy. Physically, these singular positions determine an instantaneous change in

the system number of degrees of freedom, thus leading to the degradation of its

natural stiffness. One of the most important critical aspects when a robotic structure


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interacts directly with the human body is the security A very important safety issue is

the identification and avoidance of singularity points within the robot workspace.

Fig.2.3.2.6

Left: Singularity Type I (corresponding to case 2)

Right: Singularity Type II (corresponding to case 3)

The algorithm used for the singularity analysis is based on deriving the

determinants for the two Jacobian matrices A and B, obtained from the inverse and

direct geometric models.

The reachable workspace of the parallel robotic structure can be easily

generated using either the direct or the inverse geometric model, both being

analytically determined. In this case, the inverse geometric model is used (when the

insertion point into the abdomen: B(XB, YB, ZB) is known), the generalized

coordinates of the robot q1, q2,q3, q4,q5 being determined by the use of the

generalized coordinates of the end- effector: XG, YG, ZG.

Figure 2.3.2.8 represents the isometric view of the reachable workspace of the

parallel structure emphasizing of point B, while Figure 2.3.2.7 illustrates a section

view in the workspace. The holes which appear in the workspace are the areas that

the tip of the surgical instrument (laparoscope) cannot reach.


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Fig.2.3.2.7 Lateral view of the workspace

Fig.2.3.2.8 Isometric view of the workspace


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III. References

1. PISLA, D., VAIDA, C., PLITEA, N. s.a. Model ing and simulat ion of a new

paral le l robot used in minimal ly invasive surgery, Fifth InternataionalConference on Informatics In Control, Automation and Robotics, ICINCO

2008, Funchal Madeira, Portugal, 11-15 Mai, 2008

2. PISLA, D., PLITEA, N., GHERMAN, B., PISLA, A., VAIDA, C., Kinemat ical

Analysis and Design of A New Surgical Paral le l Robot, 5th International

Workshop on Computational Kinematics May 6-8, 2009: Duisburg, Germany

3. D. PISLA. N. PLITEA and C. VAIDA, Kinemat ic Model ing and Workspace

Generat ion for a New Paral le l Robot Used in Minimal ly in vasive Surgery,

Advances in Robot Kinematics, 2008, pp. 459-469, Ed. Springer ISBN-13:

978-1-4020-8599-4

4. PLITEA N., PISLA D., VAIDA C., GHERMAN B., PISLA A. Dynamic

model l ing of a paral le l robot used in minimal ly invasive surgery,Eucomes 2008, Cassino-Italy, 17-20 Sept. 2008

5. Alin STOICA, Doina PISLA, Szilaghyi ANDRAS, Bogdan GHERMAN, Bela-

Zoltan GYURKA, Nicolae PLITEA: Kinemat ic, worksp ace and s ingular i ty

analysis o f a new paral lel robot us ed in minim al ly invasive surgery

6. Modelarea si simularea Robotilor support de curs si laborator

7. http://en.wikipedia.org

robotic systems used in surgery

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