Project 3 - Servo

Robotic Laproscopic Surgery SystemResearch

Extensive research has been done around the world on the topic of robotics and implementation of robotics in the field of medicine is still in its infancy. The concept of trusting a machine and having the confidence to get operated upon by one is new for people. Telemedicine is a new field and it is catching up fast, it is a boon for places where medical facilities are poor. The team has tried to conduct an exhaustive research on the field of robotics, sensors, laproscopic surgery systems, haptics, real time workstation. The team hopes that the research leads us to a good design, ultimately leading to a good prototype.

Index

Topic Page Number

Robotics 2

Real-Time Workstation 5

Motors 7

Sensors 11

Laproscopic Surgery 14

Haptics 19

Submitted by Team 7

1

Robotics

A robot is a virtual or mechanical artificial agent. In practice, it is usually an electro-mechanical machine which is guided by computer or electronic programming, and is thus able to do tasks on its own.

“http://en.wikipedia.org/wiki/Robot”

Actuators are devices that carry out a mechanical action of the robot under the control of a signal. They perform the actual work of the system, such as a pump stopping, a switch being moved or a light beam being turned on. Some common actuators are electric motors, solenoids and stepping motors. Actuators allow movement such as an arm or a leg type of motion. Actuators can also be used to help hold items. Effector is another name for actuator. End effectors are devices attached to the working end of a robotic arm or device. They include grippers, tools and switches. The four basic motions of a robot are called the LERT classification system in which L stands for Linear-movement in a straight line, E stands for Extension-moving an arm in or out, R stands for Rotation-moving through an arc and T stands for Twist- a spinning motion.

“http://bettscomputers.com/moodle/mod/resource/view.php?id=29”

Bettscomputers also provides an example of a similar type robot that we could build:

Two types of joints are commonly found in robots: revolute joints, and prismatic joints. Unlike the joints in the human arm, the joints in a robot are normally restricted to one degree of freedom, to simplify the mechanics, kinematics, and control of the manipulator.

2

Rotary or revolute joints

In the top two, the axis of the joint is coincident with the centre line of the link. In some designs it is normal to the distal link. This joint is often used as a waist joint.

In the bottom, the axis of the joint is normal to the link. One common use of this joint is as an elbow joint. In both cases, a revolute joint is capable of one degree of rotation, the joint variable is the angle, and the joint axis is in the Z direction. Most revolute joints cannot rotate through a full 360° , but are mechanically constrained.

Linear or prismatic joints

A prismatic joint is a sliding joint, with the axis of the joint coincident with the centre line of the sliding link. Since any prismatic form can be used for the elements of a sliding pair, it does not have a specific axis (as a turning pair does) but merely an axial direction. Nevertheless, it is convenient to choose a centre line or axis as a basis for analysis.

As with the revolute joint, there are two basic configurations: the axis can be collinear with the preceding (fixed) link, or orthogonal to it. A prismatic joint provides one degree of translation, the joint variable is the distance d, and the joint axis is in the z direction. With both types of joints, there are several common configurations of the joint with respect to the links attached to it.

“http://www.soton.ac.uk/~rmc1/robotics/argeometry.htm”

The study of motion can be divided into kinematics and dynamics. Direct kinematics refers to the calculation of end effector position, orientation, velocity, and acceleration when the

3

corresponding joint values are known. Inverse kinematics refers to the opposite case in which required joint values are calculated for given end effector values, as done in path planning. Some special aspects of kinematics include handling of redundancy (different possibilities of performing the same movement), collision avoidance, and singularity avoidance. Once all relevant positions, velocities, and accelerations have been calculated using kinematics, methods from the field of dynamics are used to study the effect of forces upon these movements. Direct dynamics refers to the calculation of accelerations in the robot once the applied forces are known. Direct dynamics is used in computer simulations of the robot. Inverse dynamics refers to the calculation of the actuator forces necessary to create a prescribed end effector acceleration. This information can be used to improve the control algorithms of a robot. http://en.wikipedia.org/wiki/Robot

In the project we intend to have end effector position control, as the space constraint plays a big role in our design joint control is of paramount importance. When operating upon a patient the laproscopic surgery system should not have joint positions which cause harm to the patient or the doctor. Therefore both have to be taken into consideration while designing the prototype. End effector would determine where the gripper arm is located on the workspace. The combination of all joints contributes to the end effector position. The end effector position is determined by the Denavit-Hartenberg convention.

FlexPicker

The group has thought about designing the laproscopic surgery system modeled on the lines of ABB’s flexpicker. It is a widely sold industrial robotic system.

"www.emeraldinsight.com/.../0490300409.html” Design Concept 1 Football Stadium Camera

The groups first design concept involved fixing the surgical arm directly above the bowl. Then, the top of the arm could be moved by a series of motors and strings attached to a frame positioned over the bowl. The idea is similar to the way cameras can be suspended over the field in football stadiums. The camera can be positioned in three dimensions above the field by adjusting the length of each string via the motor.

4

According to “http://www.skycam.tv/folders.asp?action=display&record=1”:

The patented Skycam system is virtually a flying Steadicam® -- a broadcast quality robotic camera, suspended from a cable-driven, computerized transport system. Its unique design makes Skycam the only stabilized camera system in the world that can unobtrusively fly anywhere in a defined three-dimensional space, putting the viewer right in the middle of a sporting event.

Design 2 Tracking System

The group’s second design involved a square, four-post frame that would be built around the bowl (body). The laparoscopic arm would then be supported loosely by the frame at a fixed point directly above the bowl that is close to the opening. The arm would then be moved using a guiding system at the top of the frame. It would consist of two straight beams that cross with slits in the center through which the tool would fit. The beams could then guide the tool in the x-y plane. The arm would also have a retractable link as seen in the picture below in the center of the arm that could retract the arm no matter the orientation.

Picture from “http://cache1.asset-cache.net/xc/82288088.jpg?v=1&c=IWSAsset&k=2&d=EDF6F2F4F969CEBDF9E3733021CAB98CFE4EF76ECC8C0EA4EE01F8052352DA8F”

Real-Time Workstation

The Real Time workstation is made of several software and hardware components. A Dell PC is used to run several software programs such as Simulink, Wincon, and MATLAB. This computer is connected to a Quanser Q4 board and Techron 5530 Linear Amplifier. Several manuals found online and experience from two previous labs provided additional information on the workstation.

WinCon is a real-time Windows 2000/XP application that will allow a user to run code generated from a Simulink diagram in real-time on the same PC. Data from the real-time running code may be plotted on-line in WinCon Scopes and model parameters may be changed on the fly through WinCon Control Panels as well as Simulink. The automatically generated real-time code constitutes a stand-alone controller and can be saved in WinCon Projects together with its corresponding user-configured scopes and control panels. WinCon software actually consists of two distinct parts: WinCon Client and WinCon Server. They communicate using the TCP/IP

5

protocol. WinCon Client runs in hard real-time while WinCon Server is a separate graphical interface, running in user mode.

Simulink is a software program that models many different hardware components that would be expensive to purchase otherwise such as function generators, oscilloscopes, and amplifiers. The characteristics can be changed very quickly in software where as changing them in hardware would be more time consuming. Also, components in a Simulink model can be built quicker than actually using wires and cables to connect hardware devices. Secondly, since Simulink is used in conjunction with MATLAB, more advanced circuits can be modeled using MATLAB’s programming capabilities. A third advantage is that Simulink includes several useful circuit templates within its library that require minimal specification changes. Simulink could also be used for testing a circuit in software before implementing to hardware in order to save time and money. However, one disadvantage of using Simulink would be the possibility of it introducing an error unknown to the user. Without the ability to physically measure and verify circuit parameters, the user is entrusting Simulink to provide accurate data. Finally, Simulink modeling uses ideal parameters and provides ideal data. Actual hardware provides real data and introduces some non-ideal parameters which cannot be modeled in Simulink.

The Q4 has one analog-to-digital (A/D) converter on board. The A/D converter handles four single-ended analog inputs. The range of each analog input is ±10V. The A/D samples all four channels simultaneously and holds the sampled signals while it converts the analog value to a 14-bit digital code. The results are stored in an onboard FIFO queue that can be read by software. A/D conversions can be initiated manually, or using one of the 32-bit general purpose counters on board. The Q4 has one 12-bit digital-to-analog (D/A) converter on board. The D/A converter outputs four analog outputs, each with a range of ±10V. The D/A converter is double-buffered, so new output values can be preloaded in to the D/A converters, and all analog outputs updated simultaneously. The Q4 contains two encoder chips, each handling two channels, for a total of 4 encoder inputs. Both encoder chips can be accessed in a single 32-bit operation, and both channels can be accessed at the same time per chip. Hence, all four encoder inputs may be processed simultaneously. There are four single-ended encoder inputs on the Q4 terminal board. Single-ended encoders use three signals to supply a bidirectional count: an A channel, a B channel and an I channel, or index pulse. The index pulse is not necessary for generating encoder counts, but is convenient for calibration. The Q4 data acquisition card supports 4 special function

6

I/O lines or "control lines". These signals are available on the Control header of the Q4 terminal board. There are two outputs: CNTR_OUT and WATCHDOG, and two inputs: EXT_INT and CNTR_EN.Power to the Q4 terminal board is supplied from the PC. Only the 5V power line is used.To prevent damage to the PC, the 5V line is passed through a 1A fuse before it goes to any of the circuitry on the terminal board. The power LED on the terminal board indicates whether the 5V power signal from the PC is working. Due to the protection circuitry on the terminal board and the Q4 card itself, the power at the terminal board will have a voltage level of approximately 4.7V.

The Techron 5530 amplifier provides a precision amplification of frequencies from DC to 20 KHz, with low harmonic distortion, low noise, and high damping factor. The amplifier has an input impedance of 25 kilo ohms with a power supply of one kilowatt transformer with massive computer-grade filter capacitors storing over 48 joules of energy. Output capability is 155 watts per channel minimum RMS into an 8 ohm load. When the amplifier is bridged and operates as a mono unit, output power reaches 310 watts minimum RMS into a 16 ohm load.

Motors

Servo

Hobbico CS-60 Standard Non-Bearing Servo

Features: Universal connector Small size allows for installation in most applicationsFour rubber grommets (Rectangular)One X-shaped servo wheel (Horn) One four-arm servo hornOne two-arm servo hornOne adjustable servo horn

Specs:4.8V 6VSpeed: .19 sec/60°.15 sec/60°Torque: 42 oz-in (3.06 kg-cm) 4.8V, 49 oz-in (3.57 kg-cm)Weight: 1.57oz (44.9g) Length: 1.6" (41mm), Width: .8" (20mm), Height: 1.4" (36mm)

7

Features: Universal connector fits Futaba, Hitec, JR, KO Propo, Airtronics Z,

and Tower Hobbies, not Airtronics old "A" plug. Small size allows for installation in most applications Powerful motor and molded gear train provide trouble-free operation Bushings in the drive train One year warranty

Includes: One standard sport servo

Four rubber grommets (Rectangular) One X-shaped servo wheel (Horn) Four brass eyelets One four-arm servo horn Four mounting screws One two-arm servo horn One adjustable servo horn

DC Motor

Tohoko Ricoh DC motor with optical encoder P/N: 52155301

Motor Specifications:24 vdc, 180 ma., 4600 rpm, 55 watts, no load.Lab test: 4000 rpm, 2.3 amps with 12 oz.-in. load applied.Stall torque: 70 oz.-in, 10 amps.

Encoder Specifications:2 channel quadrature400 counts square wave / rev., TTL compatible (with pull up resistor.

Dimensions:Body: 4-1/8" sq. x 1-3/8"L, (4) holes on 3-3/32" centers for mounting.Shaft: 0.237" dia. with flat x 1-1/8"L

8

Encoder Inputs

The Q4 contains two encoder chips, each handling two channels, for a total of 4 encoder inputs. Both encoder chips can be accessed in a single 32-bit operation, and both channels can be accessed at the same time per chip. Hence, all four encoder inputs may be processed simultaneously. Each encoder input channel has a 24-bit counter that can be configured in a variety of modes, including module-N for frequency-divider applications. Full 4X quadrature counting is supported as well as a non-quadrature count/direction mode. The index pulse for each channel is also fully supported. The encoder inputs are digitally filtered, with the filter clock frequency individually programmable for each channel (the maximum rate is 33 MHz). The Q4 can interrupt on a large variety of events from the encoders, such as the index pulse, carry, borrow and compare flags, error conditions, etc.

Encoder Connection

Single-ended encoders use three signals to supply a bidirectional count: an A channel, a B channel and an I channel, or index pulse. The index pulse is not necessary for generating encoder counts, but is convenient for calibration. The round DIN connectors on the terminal board are used for the encoders. The encoder connectors are the round connectors shown in light green in Figure 3 on page 10.

The pin assignments for the round DIN connector are illustrated in Figure 5 and on the terminal board itself. The pins are also enumerated in Table 3. There are no complementary signals for single-ended encoders. Note that the pin numbering of the round DIN connector is not intuitive. The pins are not numbered sequentially in a clockwise direction. The Q4 card allows the encoders to be used as 24-bit digital up/down counters as well. In this "non-quadrature" mode, the A input becomes a count input and the B input becomes a direction input. Every rising or falling edge of the CNT input (set in software), the 24-bit counter will count up or down, according to the DIR input. The index input in this case becomes an asynchronous load signal, which may be programmed to latch the counter value or to load the counter value from a preload register.

Wire colors and connectionRed White BlackVCC Signal GND

9

GND

VCC

I/LDND B/DIR

A/CNT

PWM Operation

PWM OutputsThe two 32-bit general purpose counters on the Q4 can be used as PWM outputs, with 30ns resolution. For example, each counter can generate a 10-bit, 16 kHz, PWM signal. If fewer bits of resolution are required, then a faster PWM frequency can be used. Table 1 below enumerates a few sample resolutions and the associated PWM frequencies.

Resolution PWM resolution8 bits 65 kHz10 bits 16 kHz12 bits 4 kHz

Resolution Table 1 PWM frequency versus resolutionSince the two 32-bit counters can be synchronized, the two PWM outputs can also be synchronized.The two PWM outputs are part of the Special Function I/O lines of the Q4, illustratedin Figure 1 on page 2.

PWM OutputThe PWM Output Module for the Q4 series of I/O cards programs one of the 32-bit general purpose counters to output a PWM signal on an external pin. The polarity of the CNTR_EN input may also be configured for hardware enabling/disabling of the counter. The CNTR_EN line only affects the COUNTER clock source. Unlike the Counter Output block, the PWM Output block reprograms the duty cycle every sampling instant, according to its input. Note that when the current duty cycle is non-zero, the new duty cycle is activated at the end of the next PWM period. Hence there are no spurious output values during transitions. Like the Analog Input block, there is a field for the Board Number. See the Analog Input section for a discussion of these parameters.The Clock source parameter sets which of the 2 32-bit counters to use. If COUNTER is selected, then the PWM signal will appear on the CNTR_OUT pin of the CONTROL header on the terminal board. If WATCHDOG is selected, then the PWM signal will appear on the WATCHDOG pin of the CONTROL header on the terminal board.

Generating a Square Wave OutputEach counter can generate a square wave (or PWM) output, with a frequency of up to 16.7 MHz (60ns period). To simplify programming, each counter has two modes: square wave mode and PWM mode. In square wave mode, a single write determines the output frequency. The following example programs the Counter to produce a 1 MHz output frequency. It enables the CNTR_OUT output so that the square wave appears on the Control header of the Q4 terminal board.

const uint32_T period = (uint32_T)(1e-6 / 60e-9) - 1;

/* Set the counter preload value (which will determine the period) */WriteDWordToHwMem(&pQ4->counter.sq.preload, period);

10

/* Enable the counter and force the counter to load immediately */WriteDWordToHwMem(&pQ4->counterControl, CCTRL_CNTREN | CCNTR_CNTROUTEN);

WriteDWordToHwMem(&pQ4->counterControl, CCTRL_CNTREN

Sensors

There are many types of sensors available for robotics. Sensors can be used for detecting the current position, velocity, force, strain or other physical effects. Mechanical sensors were the order of the day until the field of electrical engineering entered the realm of instrumentation. Virtually all the sensors in the market are electronically operated as it is easy to interface them with data acquisition systems such as Lab-View or Matlab. Control systems rely on feedback and sensors provide the missing link for a closed loop feedback system. The can easily be read using A/D converters. Electronic sensors are cheap and can be acquired easily. Position sensors and velocity sensors are widely used for robotics and thus wery cheap. Some of the current technologies are-

1) Potentiometer

A potentiometer is a three-terminal resistor with a sliding contact that forms an adjustable voltage divider. If only two terminals are used (one side and the wiper), it acts as a variable resistor or rheostat. Potentiometers are commonly used to control electrical devices such as a volume control of a radio. Potentiometers operated by a mechanism can be used as position transducers, for example, in a joystick. Potentiometers are used to adjust the level of analog signals (e.g. volume controls on audio equipment), and as control inputs for electronic circuits.

Rheostat – a rheostat is a linear potentiometer. It acts as a voltage divider, when a slider is moved up or down on the resistive coil the resistance changes and thus the potential also changes. It is used for measuring linear motions.

11

Joysticks used potentiometers to find the amount of motion in X or Y plane. Newer models can also measure yaw control. They have programmable buttons which can be performed for specific tasks. Saitek has introduced a gaming joystick which is capable of measuring a Z axis displacement. They are widely used for gaming and for a aircraft control.

“http://www.wisegeek.com/what-is-a-potentiometer.htm”

2) Encoder

A digital optical encoder is a device that converts motion into a sequence of digital pulses. By counting a single bit or by decoding a set of bits, the pulses can be converted to relative or absolute position measurements.Rotary encoders are manufactured in two basic forms: the absolute encoder where a unique digital word corresponds to each rotational position of the shaft, and the incremental encoder, which produces digital pulses as the shaft rotates, allowing measurement of relative position of shaft. Most rotary encoders are composed of a glass or plastic code disk with a photographically deposited radial pattern organized in tracks. As radial lines in each track interrupt the beam between a photoemitter-detector pair, digital pulses are produced. A linear encoder encodes a linear position. The sensor reads the scale in order to convert the encoded position into an analog or digital signal, which can then be decoded into position by a digital readout (DRO). Motion can be determined by change in position over time. Linear encoder technologies include capacitive, inductive, eddy current, magnetic, and optical. Optical technologies include shadow, self imaging and interferometric. Linear encoders are used in metrology instruments and high precision machining tools ranging from digital calipers to coordinate measuring machines.

“http://en.wikipedia.org/wiki/Rotary_encoder”“http://en.wikipedia.org/wiki/Linear_encoder”

Linear Encoder

Image from “www.digiball.com/encoders.htm”

12

3) Accelerometer

An accelerometer is an electromechanical device that measures acceleration forces. These forces may be static, or they could be dynamic - caused by moving or vibrating the accelerometer. By measuring the amount of static acceleration due to gravity the angle the device is tilted at with respect to the earth can be measured. Some accelerometers use the piezoelectric effect - they contain microscopic crystal structures that get stressed by accelerative forces, which causes a voltage to be generated. Another way to do it is by sensing changes in capacitance. They are widely used in consumer electronics, inertial navigation system, building and structural monitoring and robotics.

“http://en.wikipedia.org/wiki/Accelerometer”

4) LVDT

Linear variable differential transformer - is a type of electrical transformer used for measuring linear displacement. The transformer has three solenoidal coils placed end-to-end around a tube. The centre coil is the primary, and the two outer coils are the secondaries. A cylindrical ferromagnetic core, attached to the object whose position is to be measured, slides along the axis of the tube. An alternating current is driven through the primary, causing a voltage to be induced in each secondary proportional to its mutual inductance with the primary. As the core moves, these mutual inductances change, causing the voltages induced in the secondaries to change. The coils are connected in reverse series, so that the output voltage is the difference (hence "differential") between the two secondary voltages. When the core is in its central position, equidistant between the two secondaries, equal but opposite voltages are induced in these two coils, so the output voltage is zero. LVDTs are used for position feedback in servomechanisms, and for automated measurement in machine tools and many other industrial and scientific applications.

“http://www.macrosensors.com/lvdt_macro_sensors/lvdt_tutorial/lvdt_primer.pdf”

5) FSR

FSRs are sensors that allow you to detect physical pressure, squeezing and weight. They are simple to use and low cost. FSR's are basically a resistor that changes its resistive value (in ohms Ω) depending on how much its pressed. These sensors are fairly low cost, and easy to use but they're rarely accurate. They also vary some from sensor to sensor perhaps 10%. So basically when you use FSR's you should only expect to get ranges of response. While FSRs can detect weight, they're a bad choice for detecting exactly how many pounds of weight are on them.

“http://www.trossenrobotics.com/store/p/3219--5-Inch-Force-Sensing-Resistor-FSR-.aspx?feed=Froogle”

13

Laparoscopic Surgery

Laparoscopic surgery, also called minimally invasive surgery (MIS), band-aid surgery, keyhole surgery is a modern surgical technique in which operations in the abdomen are performed through small incisions (usually 0.5-1.5cm) as compared to larger incisions needed in traditional surgical procedures. Laparoscopic surgery includes operations within the abdominal or pelvic cavities. There are a number of advantages to the patient with laparoscopic surgery versus an open procedure. These include reduced pain from infection and hemorrhaging, shorter recovery time, shorter hospital time, smaller incisions, and a reduced risk of acquiring infections due to reduced exposure of internal organs.

The key element in laparoscopic surgery is the use of a laparoscope. There are two types: (1) a telescopic rod lens system, that is usually connected to a video camera (single chip or three chip), or (2) a digital laparoscope where the charge-coupled device is placed at the end of the laparoscope, eliminating the rod lens system. Also attached is a fiber optic cable system connected to a 'cold' light source (halogen or xenon), to illuminate the operative field, inserted through a 5 mm or 10 mm cannula or trocar to view the operative field. The abdomen is usually insufflated, or essentially blown up like a balloon, with carbon dioxide gas. This elevates the abdominal wall above the internal organs like a dome to create a working and viewing space. CO2 is used because it is common to the human body and can be absorbed by tissue and removed by the respiratory system. It is also non-flammable, which is important because electrosurgical devices are commonly used in laparoscopic procedures.

“http://en.wikipedia.org/wiki/Laparoscopic_surgery”

14

Uses of Laparoscopic Surgery

There are many uses for laparoscopy. One common use is to find the cause of a health problem, such as chronic pelvic pain (pain that lasts for more than 6 months). Laparoscopy is used for some procedures and to treat some conditions as follows:

Endometriosis—If you have endometriosis, laparoscopic surgery may be done to treat it. During this procedure, the endometriosis tissue is removed with a laser, heat, or other methods.

Fibroids—Fibroids are growths that form inside the wall of the uterus or outside the uterus. When fibroids cause pain and heavy bleeding, laparoscopy sometimes can be used to remove them, depending on how many fibroids there are, how big they are, and where they are located.

Ovarian cysts—Some women have cysts (fluid-filled sacs) that develop on the ovaries. These cysts may cause only mild discomfort. Over time, ovarian cysts often go away on their own. But if they do not, your doctor may suggest that they be removed with laparoscopy.

Ectopic pregnancy—Laparoscopy may be done to remove an ectopic pregnancy in the fallopian tube.

Sterilization—In this operation, the doctor uses the laparoscope as a guide to block the fallopian tubes by cutting, clipping, or burning them. After this procedure, a woman can no longer get pregnant. It is meant to be a permanent method of birth control.

Laparoscopically assisted vaginal hysterectomy (LAVH)—LAVH is a type of hysterectomy in which the uterus is removed through the vagina. The laparoscope is used to guide the procedure.

Laparoscopic hysterectomy—In this procedure, the uterus is detached from inside the body. Several small incisions are made in the abdomen for the laparoscope and the instruments that are used to remove the uterus. The uterus is removed through these incisions in small pieces.

Pelvic problems—Laparoscopic surgery can be used to treat urinary incontinence and pelvic support problems, such as uterine prolapse.

“http://www.acog.org/publications/patient_education/bp061.cfm”

Most intestinal surgeries can be performed using the laparoscopic technique. These include surgery for Crohn’s disease, ulcerative colitis, diverticulitis, cancer, rectal prolapse and severe constipation. In the past there had been concern raised about the safety of laparoscopic surgery for cancer operations. Recently several studies involving hundreds of patients have shown that laparoscopic surgery is safe for certain colorectal cancers.

“http://www.fascrs.org/patients/treatments_and_screenings/laparoscopic_surgery/”

Laparoscopic surgery can also be used to remove the gallbladder and gallstones.

15

Limitations of Laparoscopic Surgery The human hand is a wonderful structure and provides multitude of different functions

during open surgery. This function is absent during standard laparoscopic surgery since the abdomen is closed and the procedure is performed with long surgical instruments inserted from the outside into the abdomen.

Two dimensional image of the laparoscope: The image transmitted by the laparoscopic camera that surgeon utilizes as his eyes is a two dimensional image. For some procedures this is a major limitation because of the poor depth perception that is associated with two dimensional images.

Retraction of internal organs: During open surgery insertion of the hand into the abdomen allows the surgeon to move the intestine and other organs away from the site of the surgery. During standard laparoscopic surgery the hand is not introduced into the abdomen and introducing long thin instruments into the abdomen performs the surgery. Retraction of internal organs is often a major problem for some procedures.

Limitation of instruments: the standard instruments in laparoscopic surgery are long thin instruments. These instruments are poorly suited for many complex laparoscopic procedures.

“http://www.surgery.usc.edu/divisions/tumor/pancreasdiseases/web%20pages/laparoscopic%20surgery/adv%20in%20lap%20surg.html”

Da Vinci Surgical System

The da Vinci System consists of a surgeon’s 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, act as a scalpel, scissors, bovie, or unipolar or dipolar electrocautery instruments. The fourth arm is for 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 3-D image of the procedure, meanwhile maneuvering the arms with two foot pedals and two hand controllers. The da Vinci System scales, filters and translates the surgeon's hand movements into more precise micro-movements of the instruments, which operate through small incisions in the body.

To perform a procedure, the surgeon uses the console’s master controls to maneuver the patient-side cart’s three or four robotic arms (depending on the model), which secures the instruments and a high-resolution endoscopic camera. 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 surgeon’s hand movements. The da Vinci System incorporates multiple, redundant safety features designed to minimize opportunities for human error when compared with traditional approaches. At no time is the surgical robot in control or autonomous; it operates on a "Master:Slave" relationship, the surgeon being the "Master" and the robot being the "Slave."

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

16

Vinci System’s 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. However, surgical procedures performed with the robot take longer than traditional ones. Critics have pointed out that hospitals have a hard time recovering the cost and that most clinical data does not support the claim of improved patient outcomes. The robot costs on average $1.3 million in addition to several hundred thousand dollars of annual maintenance fees. “http://en.wikipedia.org/wiki/Da_Vinci_Surgical_System”

The system relays some force feedback sensations from the operative field back to the surgeon throughout the procedure. This force feedback provides a substitute for tactile sensation and is augmented by the enhanced vision provided by the high-resolution 3D view.

Some of the major benefits experienced by surgeons using the da Vinci Surgical System over traditional approaches have been greater surgical precision, increased range of motion, improved dexterity, enhanced visualization and improved access. Benefits experienced by patients may include a shorter hospital stay, less pain, less risk of infection, less blood loss, fewer transfusions, less scarring, faster recovery and a quicker return to normal daily activities. None of these benefits can be guaranteed, as surgery is necessarily both patient- and procedure-specific.

Currently, The da Vinci Surgical System is being used in hundreds of locations worldwide, in major centers in the United States, Austria, Belgium, Canada, Denmark, France, Germany, Italy, India, Japan, the Netherlands, Romania, Saudi Arabia, Singapore, Sweden, Switzerland, United Kingdom, Australia and Turkey.

“http://www.davincisurgery.com/davinci-surgery/frequently-asked-questions.html”

The U.S. Food and Drug Administration (FDA) has cleared the da Vinci® Surgical System for adult and pediatric use in urologic surgical procedures, general laparoscopic surgical procedures, gynecologic laparoscopic surgical procedures, general non-cardiovascular thoracoscopic surgical procedures and thoracoscopically assisted cardiotomy procedures. The da Vinci System may also be employed with adjunctive mediastinotomy to perform coronary anastomosis during cardiac revascularization.

Representative Uses: The da Vinci System has been successfully used in the following procedures, among others:

Radical prostatectomy, pyeloplasty, cystectomy, nephrectomy, ureteral reimplantation Hysterectomy, myomectomy and sacrocolpopexy Cholecystectomy, Nissen fundoplication, Heller myotomy, gastric bypass, donor

nephrectomy, adrenalectomy, splenectomy and bowel resection

17

Internal mammary artery mobilization and cardiac tissue ablation Mitral valve repair, endoscopic atrial septal defect closure Mammary to left anterior descending coronary artery anastomosis for cardiac

revascularization with adjunctive mediastinotomy

“http://www.intuitivesurgical.com/products/fdaclearance/index.aspx ”

Zeus Surgical System

The ZEUS Surgical System is made up of an ergonomic surgeon control console and three table-mounted robotic arms, which perform surgical tasks and provide visualization during endoscopic surgery. Seated at an ergonomic console with an unobstructed view of the OR, the surgeon controls the right and left arms of ZEUS, which translate to real-time articulation of the surgical instruments. A third arm incorporates the AESOP Endoscope Positioner technology, which provides the surgeon with magnified, rock-steady visualization of the internal operative field.

The ZEUS Surgical System features the following components:

Video Console Primary Video Monitor up to 23"W x 23"D Flat Panel Monitor: with support for an additional flat panel monitor

Surgeon Control Console

Touch Screen Monitor Support Arms and Surgeon Handles Mounting Areas: for speakers; access to controller front panels; access to PC and

HERMES™ Control Center; mounting shelves for housing Control Units

Six Degrees of Freedom

4 Motorized o Up and Down o In and Out o Shoulder: Back and Forth o Elbow: back and forth

2 Floating o Forearm: back and forth - safety function: float away to avoid ramming something o Wrist

1 Fixed change in angle o Elbow Tilt (+/- 3 degrees)

“http://library.thinkquest.org/03oct/00760/Zeus%20System.htm”

18

Haptics

Haptics is the study of how to couple the human sense of touch with a computer-generated world. One problem with current virtual reality systems is the lack of stimulus for the sense of touch. For example, if a user tries to grab a virtual cup there isn't a non-visual way to let the user know that the cup is in contact with the user's virtual hand. Also, there isn't a mechanism to keep the virtual hand from passing through the cup. Haptic research attempts to solve these problems and can be subdivided into two sub-fields, force (kinesthetic) feedback and tactile feedback.

Force feedback is the area of haptics that deals with devices that interact with the muscles and tendons that give the human a sensation of a force being applied. These devices mainly consist of robotic manipulators that push back against a user with the forces that correspond to the environment that the virtual effector is in.

Tactile feedback deals with the devices that interact with the nerve endings in the skin which indicate heat, pressure, and texture. These devices typically have been used to indicate whether or not the user is in contact with a virtual object. Other tactile feedback devices have been used to simulate the texture of a virtual object.

Haptic Devices

PHANTOM Omni Haptic Device

http://www.sensable.com/documents/images/LargePHANTOMOmniImage.jpgThe SensAble Technologies PHANTOM® product line of haptic devices makes it possible for users to touch and manipulate virtual objects. The PHANTOM Omni model is the most cost-effective haptic device available today. Portable design, compact footprint, and IEEE-1394a FireWire* port interface ensure quick installation and ease-of-use.

Highlighted Features

Six degree-of-freedom positional sensing Portable design and compact footprint for workplace flexibility Comfortable molded-rubber stylus with textured paint for long term use and secure grip Removable stylus for end-user customization Two integrated momentary switches on the stylus for ease-of-use, and end-user

customization Compact workspace for ease-of-use Constructed of metal components and injection-molded plastics

“http://www.sensable.com/haptic-phantom-omni.htm”

19

Rutgers Master II

Rutgers Master II- is a haptic interface for dexterous hand interactions with virtualenvironments. Thumb, index, middle, and ring fingertips are connected to the pneumatic actuators. Actuators are connected to the L-shaped base, which is attached to the palm. Sensors can be updated 435 records/sec and each ¯nger generates force up to 10Nper finger with 12bit resolution. It can control valves by 300 Hz and ¯ngertips by 10Hz. It usesa virtual hand model to estimate joint angle of each finger. This haptic device is different from other haptic interface in that it has four contact points which can be controlled separately. In addition, this device usually uses 3D hand model to interact with the virtual world. So, it really needs haptic rendering with a 3D hand model and objects.

“http://yu.ac.kr/~cvpr/doc/dimacsbem.pdf”

20