A MICRO ROBOTIC ARM FOR A SELF PROPELLING COLONOSCOPE

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A MICRO ROBOTIC ARM FOR A SELF PROPELLINGCOLONOSC
OPE

• By
• Jyothsna Mallavarapu
• Distributed Sensors and Actuators via Electronic-
  Textiles
• By
• Sharmila Pichai
• A miniature manipulator for integration in a self
  propelling endoscope
• By
• Aneesha Nakka

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A MICRO ROBOTIC ARM FOR A SELF PROPELLINGCOLONOSC
OPE
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Introduction

• Present colonoscopes are semi-flexible tubes that
  are inserted by pushing and pulling on the tail.
• The system consists of a self-propelling module
  with a micro robotic manipulator at the tip and a
  flexible tail connecting the system to the
  outside world.

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• Design of Arms based on Shape Memory Alloys
  (SMAs)
• 1.Modulator actuator arm design
• 2.Continuous actuator arm design

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Modulator actuator arm design
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• The design consists of stacking several modules
  and form spinal column
• 1. Adjacent modules can be rotated 90 degrees to
  each other so that two dimensional bending
  actuator is obtained
• 2.Each module has 3 stable positions, the total
  number of stable configurations for a stack of N
• modules is equal to 3N. Twelve modules are
• needed for a stroke of 90 in 2 directions

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Miniature Bending actuator design

• 1. The actuator consists of 10 parts and all
  parts are glued together
• 2. Electrical isolation between strip and body is
  obtained by anodisation of the aluminium
  body.
• 3.The strip generates Torque of 1.2 Nmm

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• Disadvantages of Design
• Due to non uniform temperature of the SMA a
  global warming of whole device occurs.
• Global heating of the device leads to an
  increased surface temperature which is not
  acceptable for a medical application.

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Continuous actuator arm design

• Design contains planetary gear system to multiply
  the stroke of the SMA strip
• This system reduces the Torque a factor of 3 and
  4 and gives useful torque of 0.25 Nmm

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• Tool design with SMAs
• 1.SMA driven gripper
• 2.Hydraulic tool

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SMA driven gripper
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• Disadvantages
• The length of the strip that is needed makes the
  actuator too long
• thermal isolation between SMA strip and actuator
  body is low to prevent the whole body to warm up

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Hydraulic Tool
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• Advantage
• Hydraulic actuators are fast ,safe and
  reliable operation.
• Comparison of SMA and Hydraulic Actuators
• 1. SMAs have a very high work density because
  percentage of SMA material in the system is quite
  low
• 2.volume of the displaced water is high in
  comparison to the total system volume in
  hydraulic actuator

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Conclusion

• The aim to present this paper is to have 180
  degrees rotation available at the tip of the
  endoscope without any mechanical driving system
  connected .