ME-2501
03/25/2003
Precision Design in Surgical Tools
Presented by:
Hugo Ramirez
Eugene Kushnir
ME-2502
03/25/2003
Microsurgery Overview Current Designs
DaVinci Surgical System Harmonic Scalpel Microsurgical Tele Robotic System
Future of Microsurgery References Questions / Comments
Agenda
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03/25/2003
Principles for the development of Microsurgery Devices
Limits of Human precision Involuntary and inadvertent movements Noise and error in hand motion
Convert Procedures to Minimally Invasive Increase Precision
Increase recovery time Decrease post-operative pain Enhance dexterity
Enable Remote Participation Surgical Systems Neuroendoscopy
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03/25/2003
Analysis of the Microsurgical Environment
Table 1. Microsurgical environment general specifications
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03/25/2003
Analysis of the Microsurgical Environment
Figure 1. Microsurgical environment general force specifications
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Material Qualities Comparison
MATERIAL PROPERTY USES WEDLING FORMABILITY
304 STAINLESSSTEEL
CROMIUM = 12%
* STRESS CORROSION CRACKING ABOVE 60ºC* PITTING IN CHLORIDE ENVIRONMENTS
MOST WIDELY USED SST
* SEMICONDUCTOR IND.* SPRINGS
EXCELLENT
USUALY NO ANNEALING
EXCELLENT
316L STAINLESSSTEEL
CROMIUM = 20%(EXTRA LOW CARBON)
* MOLYBDENUM ADDS RESISTANCE TO PITTING, SULFURIC AND HYDROCHLORIC ACID, ALKALINE CHLORIDES
* PHARMACEUTICAL* JET ENGINE PARTS* PAPER PROCESSING
GOOD
ANNEALING REQUIRED
EXCELLENT
Ti6Al4V TITANIUM(Ti-90, Al-6, V-4)
* CORROSION RESISTANCE IN NATURAL AND CHEMICAL ENVIRONMENTS* RESISTANCE TO CHLORIDES* RESISTANT TO STRESS CORROSION CRACKING* CAN BE ANODIZED
MOST WIDELY USED ALLOY
* MEDICAL TOOLS DIFFERENT COLORS TO PREVENT REFLECTION OF LIGHT (EX. EYE SURGERY)* AEROSPACE* POWER GENERATION IND.
FAIR
ANNEALING REQUIRED
* GALLING HIGHER THAN STEEL* LOWER MODULUS OF ELASTISITY CAUSES SPRING-BACK* LOWER THAN STEEL DUCTILITY
NYLON 12(30% GLASS)
* LIGHT AND SELF LUBRICATING* LOW WATER ABSORBTION <0.5%
* MATERIAL OF CHOICE FOR GEARS IN MOTOR HEADS WHERE WEIGHT AND COST IS IMPORTANT
N/A EXCELLENT
TABLE 2. MATERIAL QUALITY
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Material Properties Comparison
MATERIAL DENSITY(lb/in^3)
YIELD STRENGTH(psi)
MODULUS OFELASTISITY (ksi)
CTE(in/in-ºF)
HARDNESSBRINELL (3000kg)
304 STAINLESSSTEEL
0.289 31200 28000 9.61 123
316L STAINLESSSTEEL
(EXTRA LOW CARBON)0.289 34100 28000 8.89 146
Ti6Al4V TITANIUM(Ti-90, Al-6, V-4)
0.163 120000 16500 4.78 334
NYLON 12(30% GLASS)
0.037 8702 305 27.8Rockwell R
(1/2" steel ball, 60kg)108
TABLE 3. MATERIAL PROPERTIES
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03/25/2003
Da Vinci System Overview
Illustration courtesy Dr. Akhil Madhani
Da Vinci Surgical System – Three arm tele-operated robot
Degrees of Freedom (DOF) – 34-DOF Total Arms – 3-DOF for operation and 6-DOF for initial position on the
ports (incisions) plus 4-DOF for the endoscope Active End Effector (EndoWrist) – 3-DOF plus grip
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DaVinci System Overview (continued)
EndoWrist
Position Mechanism
0.4 inchIncision
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DaVinci Position Actuators – Arm
Master DeviceSurgeon Control System
Slave DeviceEndoWrist Control System
Force-Feedback System 1. Master Device – Servo-motors and encoders receive input from a
surgeon’s hands actuating robotic arms 2. Slave Device – Arms exert forces back through the console
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DaVinci Position Actuators – Arm (continued)
Click on image to Play/Pause Video Click on image to Play/Pause Video
COMPONENTS/SUBSYSTMES PARAMETERS
MOTORS(TOTAL OF 36 MOTORS)
13mm - 35mm
MOTOR GEAR HEARS(NYLON 12 GEARS FOR 13mm
SIZES)
REDUCTION 4:1 TO 20:1TORGQUE 0.15 lbf-ft TO 1.70 lbf-ftBACKLASH 0.7°
FEEDBACK SYSTEM(REAL TIME < 35 msec.)
* OPTICAL ROTARY WITH UP TO 2000 COUNTS/REV.* MAGNATIC LINEAR ENCODERS* PRECISION <50 m
SPEED (MAX.)ROTATIONAL 180°/secLENEAR 40 mm/sec
BALL SCREWS PRELOADED - 0° BACKLASH
TABLE 3. POSITION SYSTEM
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03/25/2003
DaVinci Position Actuators - EndoWrist
Ultrasonic Shears
EndoWrist – 4-DOF
Motion controlled by tendon like cables to simulate human wrist movement
Modular design allows various surgical accessories and instruments to be used
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Harmonic Scalpel
High frequency ultrasonic energy to actuate the cutting blade. Simultaneous cutting and blood coagulation due to high speed Advantages:
Fewer instrument exchanges, Improved visibility in the surgical field Less tissue charring and dehydration (coagulation occurs at less than
100ºC) Disadvantages:
High initial cost
ULTRASONIC SCALPEL BODY DSP CONTROLED ULTRASONIC WAVE GENERATOR (55.5 KHZ)
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Harmonic Scalpel (continued)
The ultrasonic vibration of the cutting blade is generated by a piezoelectric ceramics that expand and contract under power from a 55.5 KHz wave generator.
Vibration Range: 50 to 100 µm (function of power level) 100 µm – Faster cutting less coagulation 50 µm – Slower cutting more coagulation
Tissue
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03/25/2003
System Overview (Microsurgical Tele Robotic System)
Modified Steward type platform for the Micro-manipulator
6-DOF Positional Accuracy - within 50μm Workspace - 20mm × 20mm × 20mm
Master: Force-reflecting haptic master device. Slave: Surgery micro-manipulator
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Microsurgical Tele Robotic System - Slave
Stewart Platform Schematic
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Microsurgical Tele Robotic System - Master
Modified Stewart Platform Schematic
X
Y
ZBase
5 bar Linkage (Ball-Joined –top, Pin-Joined-bottom)
Platform
End Effector
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FUTURE OF MICROSURGERY
The New Order of Surgery Patient dataset of MRI, CT, and other physiological data Systems for interfacing anatomical and physiological data with finite ele-
ment modeling tools A surgical model to construct a simulation of the surgery High Precision Tele-robotic Surgical systems
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QUESTIONS / COMMENTS
Questions, comments and group discussion
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References
Chintwood, W. Randolph Jr, MD. “Enddoscopic Robotic Coronary Surgery- Is this Reality or Fantasy?” The Journal of Thoracic and Cardiovascular Surgery. July 1999; Volume 118: 1-3
Dong-Soo Kwon, et. al, “Microsurgical Telerobot System” Proc. of the IEEE/RSJ Int. Conf. on Intelligent Robots and Systems,pp. 945-950, 1998
Guthart, Gary, Salisbury, Kenneth Jr. “The IntuitiveTM Telesurgery System: Overview and Application” Proc. of IEEE Int. Conf. on Robotics and Automation, pp. 618-621, 2000
K.Y.Woo, B.D.Jin, D.S.Kwon, “A 6 DOF Force Reflecting Hand Controller Using the Fivebar Parallel Mechanism,” Proc. of IEEE Int. Conf. on Robotics and Automation, pp. 1597-1602, 1998
” Surgical Robots”, National Horizon Scanning Centre, University of Birmingham, Edgbaston, Birmingham, January 2000.
Yamano Ikuo, et. al, “Method for Controlling Master-Slave Robots using Switching and Elastic Elements” Proc. of IEEE Int. Conf. on Robotics and Automation, pp. 1717-1722, 2002.
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References
www.intuitivesurgical.com
www.cybelius.com
www.thetrocar.net
www.harmonicdrive.de
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Surgical System Applications
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Patient care advantages
less post-operative pain
less blood loss
lower risk for infection
decreased recovery times
reduced time in hospital
enhanced cosmetic results
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Motor Specifications
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Surgical System video Camera
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03/25/2003
Block Diagram of EndoWrist
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Human Arm Degrees of Freedom
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03/25/2003
Position Actuator (Microsurgical Tele Robotic System)
Harmonic Servo Motor
Advantages Positioning accuracy
and repeatability Not back-drivable Zero-Backlash High efficiency
Motor in Motion Simulation
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03/25/2003
Harmonic Servo Motor Operation Principle
As soon as the Wave Generator starts to rotate clockwise, the zone of tooth engagement travels with the major elliptical axis.
When the Wave Generator has turned through 180 degrees clockwise the Flexspline has regressed by one tooth relative to the Circular Spline.
Each turn of the Wave Generator moves the Flexspline two teeth anti-clockwise relative to the Circular Spline.