Koerner Family Fellowship Progress Update

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Koerner Family Fellowship Progress Update
Telemanipulation of a moving target Applications
to robot-assisted surgery

• Christopher W. Kennedy
• Advisor Dr. Jaydev P. Desai
• Program for Robotics, Intelligent Sensing, and
  Mechatronics (PRISM) Laboratory
• MEM Department, Drexel University
• 6/11/04

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Motivation

• Cardiovascular disease is a leading cause of
  death worldwide
• There are over 700,000 Coronary Artery Bypass
  Graft (CABG) procedures performed annually around
  the world
• An arrested heart provides a still and flaccid
  field that can be manipulated easily to expose
  the vessels
• Cardiopulmonary bypass (CPB) carries risks such
  as
• Systemic inflammatory response
• Stroke and neurocognitive defects
• Cardiac complications such as perioperative
  myocardial infarction

Off-pump CABG (OPCABG) procedure with
stabilization by Octopus stabilizer (Medtronic)
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Proposed solution

• Project goals
• Develop a system for robotically-assisted
  sutureless coronary anastomosis during a CABG
  procedure
• Present a stationary operative site to the
  surgeon while providing both visual and force
  feedback
• Decouple macro and micro motions for
  telemanipulation
• Macro motion to cancel motion of heart surface
  by 6 DOF robot
• Micro motion to perform surgical procedure by 2
  DOF robot

Proposed system for robotically-assisted
sutureless coronary anastomesis.
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Research and Contribution during Koerner
Fellowship Tenure

• Research work completed
• Experimental testbed for medical teleoperation
• Model-based control of a Mitsubishi PA-10 robot
  arm to minimize interaction forces in surgery
• Visual servoing for motion cancellation

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The Mitsubishi PA-10 Robot Arm

• Accurate modeling of the inherent dynamics of the
  robot manipulator is essential for minimizing
  tissue damage during a surgical procedure
• Mitsubishi PA-10 robot arms harmonic drives
  allow for
• Backdrivability
• Precise positioning capabilities
• Zero backlash

The Mitsubishi PA-10 Robot Arm.
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Harmonic drive systems

• Compact, light-weight, and have torque ratios
  between 301 and 3201
• Harmonic drives are composed of three components
• Wave generator
• Flexspline
• Circular spline
• Flexspline has two teeth fewer than the circular
  spline
• One revolution of the input causes relative
  motion between the flexspline and the circular
  spline equal to two teeth

Harmonic Drive Components
Displacement, velocity and torque relationships
for harmonic drives.
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Harmonic drive operation
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Proposed control system
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Model Implementation
Feedforward model of Mitsubishi PA-10 allows the
robot to manipulated by hand.
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Motion cancellation

• Motion-cancellation goal target object appears
  motionless in image
• Solution Velocity feedforward/feedback visual
  servoing

Velocity feedforward/feedback controller for
visual servoing.
Eye-in-hand system.
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Motion cancellation experiment
Velocity feedforward/feedback motion cancellation
experiment.
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Motion cancellation (cont.)

• Sinusoidal motions parallel to the image plane
  were tracked

Results of motion cancellation experiment for the
image x-axis.
Results of motion cancellation experiment for the
image y-axis.
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2 DoF robot for micro motion

• Custom 2 DoF robot
• Provides planar motion relative to robot
  end-effector
• Actuated by 13 mm DC motors manufactured by Maxon
• Gearbox with 671 ratio
• Optical encoders with resolution of 16
  counts/turn of the motor axis

Custom 2 DoF platform for micro motion.
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2 DOF motion platform
2 DOF motion platform for micro motion in
telesurgical system.
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Conclusions and Acknowledgements

• The research work performed during my Koerner
  Family Fellowship tenure is a significant
  contribution to the field of medical robotics and
  will allow me to achieve my graduation goal of
  8/04
• Thank you!