Realistic Hardware Interface to Digital Surgery

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Realistic Hardware Interface to Digital Surgery

• Syed Ali
• Computer Haptics and
• Virtual Environments Lab
• JEC 3205

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Purpose

• Create hardware that will interface with existing
  virtual surgery simulations (VSS) and allow for
  more realistic control over virtual laparoscopic
  tools
• Implement a cost effective method of using basic
  electrical components to make hardware that will
  connect to the laparoscopic tools
• Currently Prototyping hardware on a scissor
  laparoscopic tool that interface with a VSS
• End Goal to Design Create a system that will
  interface multiple laparoscopic tools with VSS

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Background Information

• ACor Lab has developed virtual surgery
  simulations programs that use haptic devices to
  provide feedback during simulations
• The haptic devices use a pen-like tool to
  interact with the virtual organs/tissues
• We need an advanced interface so that the virtual
  simulation is more realistic
• We are developing electronic hardware based on
  existing laparoscopic tools models to
  realistically emulate
• Scissors, Clippers, Graspers Dissectors

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Hardware Interface Design

• A Laparoscopic scissor tool usually has two
  variable
• Scissor Opening
• Scissor Rotation
• The Scissor tool has a handle that controls the
  opening angle of the tool and a wheel that
  controls the rotation of the tool tip
• Current method used to track the opening angle of
  the tool tip is to put a potentiometer where the
  tool handle rotates (pivots)
• See illustration on next slide

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1st Iteration

• Issues
• Used a large Potentiometer to track handle
  rotation
• Did not realistically capture the length of the
  scissor tool
• Very heavy and hard to handle

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Hardware Interface Design

• To track the rotation of the tool tip we wanted
  to use a system similar to the scroll wheel in a
  mouse.
• Scroll wheels (currently) use optical systems to
  track the rotation of the scroll wheel
• Older systems used rotary encoders to rotation
  tracking
• Current design is to use a rotary encoder to
  track position
• However this is provides digital output and not
  analog output (like the potentiometers)

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Hardware Interface Controller

• There are a couple of interface devices that will
  help us send data to the computer program
• Inexpensive microprocessor
• Arduino (Hobby/Artist Input/Output controller)
• Data Acquisition Unit
• Reads Analog Digital Signals from electronics

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Data Acquisition Units

• OnTrak DA
• Currently using
• 100
• Arduino Controller
• Easy to Implement
• 35

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Current Issues

• Working on a better way to track the handle
  position
• Using a Linear/Slide Potentiometer to interface
  with the Tool Handle
• How to track rotation with out using a rotational
  encoder
• Using a rotational potentiometer that has
  unlimited rotation
• Accomplished by removing rotation stopper
• Requires additionally programming and data
  smoothening for accurate and stable program input
• Computationally intensive

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Rotary Encoder Information

• Rotary Encoder is used to track rotation.
• Unlimited Rotation
• Implementation Requirements
• Write C Code to properly interpret output signals
  
• Interface with the tool tip/shaft

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2nd Iteration

• Improvements
• Smaller Potentiometer - Lower Inertia, more
  realistic feel
• Shaft to Emulate real tool length - structurally
  stronger
• Rotational Potentiometer - to help track/send
  tool tip rotation

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Future Plans

• Create another prototype using
• a linear/slide potentiometer
• Rotary encoder
• Write C code to convert digital signal to easily
  interpretable data input
• Implement Arduino Controller to make the system
  cost effective
• Create a professional system that hides back end
  from the user

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About Me

• Syed Reza Ali (alis3_at_rpi.edu)
• Mechanical Electrical Engineer 2008
• Interests
• Haptics Hardware Interface Research
• Personal Artist Robotics Research
• Human Computer Interaction
• Human Technology Interaction
• 3D Graphics Animation Electronic Arts
• Digital Media Design
• www.rpi.edu/alis3