Novel Core Technologies and Systems for Magnetic Resonance Compatible Robotics
Von Sternberg, Nicholas Craig 1986-
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This dissertation presents design and validation of several systems and technologies for magnetic resonance imaging (MRI) compatible positioning. The research began as the development of an MRI compatible actuated phantom, which required precise motion through remote actuation. The phantom, which operates from 18 remotely actuated stepper motors, provided motion inside the MRI scanner with submilimeter accuracy and minimal zipper artifacts induced to the images. The motion requirements lead of the phantom project led to the development of a closed-loop motor controller which enabled such accuracy. Maximum absolute error of the tracking a sigmoid function was 0.012 rad, four times the precision of the motor itself. Through the process of developing the actuated phantom, ideas for a flexible, intrinsically MRI compatible method of force transmission were transformed into the Solid Media Flexible Transmission (SMFT) technology presented which can provide force transmission to an end effector up to 4 meters away from the remote actuator without the use of electrically conductive or magnetically susceptible materials. A tool positioning robot was built to demonstrate the technology and SNR reduction of as little as 5% was achieved by filtering the motor drive signals. The methods and experiments provided within demonstrate that traditional electromagnetic motors can be used inside the MRI room with better kinematic results than pneumatic or hydraulic systems and higher force output than piezoelectric motors with the use of the novel SMFT force transmission method.