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Title page for ETD etd-07142015-105237


Type of Document Dissertation
Author Di Natali, Christian
URN etd-07142015-105237
Title Magnetic Medical Capsule Robots
Degree PhD
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Pietro Valdastri Committee Chair
Karl Zelik Committee Member
Keith Obstein Committee Member
Nabil Simaan Committee Member
Robert Webster Committee Member
Keywords
  • control
  • endoscopy
  • surgery
  • magnetic localization
  • magnetic device
  • medical robotisc
Date of Defense 2015-05-21
Availability unrestricted
Abstract
Over the last decade, researchers have started exploring the design space of Medical

Capsule Robots (MCRs): devices that can operate within the human body performing

functionalities such as diagnosing, monitoring, and treating diseases. Clinical applications

for MCRs span from abdominal surgery to endoscopy. MCRs are severely resource constrained

devices in size and in available mechanical/electrical power.

Magnetic manipulation is becoming one of the main strategies for MCRs navigation and

remote actuation, as it allows the transmission of forces across a physical barrier without

requiring an internal source of power.

The current state of the art lacks proprioceptive systems able to control magnetic actuation

to enable MCRs to perform medical procedures. This dissertation presents controllable

strategies for remote and local magnetic manipulation of MCRs combined with real-time

proprioceptive sensing.

The study focuses on two main applications: magnetic pose detection for navigation

of Wireless Capsule Endoscope (WCE) along the gastrointestinal (GI) tract, and Local

Magnetic Actuation (LMA) for powering Degrees of Freedoms (DOFs) of abdominal surgical

robots.

The proposed magnetic pose detection algorithms were successfully applied to remote

navigation on several WCE prototypes during in-vivo trials. Two di erent approaches

for magnetic pose detection compatible with magnetic actuation based on sensor fusion

are presented and evaluated. The rst approach takes advantage of the magnetic eld

mathematical derivation based on cylindrical symmetry, performing absolute pose detection

for 50 Hz real-time systems. The second algorithm achieves a refresh rate of 1 kHz applying

a least square interpolation to the nite element solution of the magnetic eld, to obtain

Jacobians closed-form expression function of capsule poses changes. A third algorithm

estimates the force generated by magnetic coupling along the magnetization direction to

study the force required to drag WCEs along the GI tract.

The second topic covers the design and control for the LMA. This concept allows

the transmission of rotary motion by applying the magnetic spur gear concept to actuate

robotic DOFs of MCRs. The proposed dynamic model is used to design closed-loop control

strategies. Two surgical tools based on the LMA are presented: a single-DOF retractor and

a 4-DOF manipulator.

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