Modeling and Experiments for a Class of Robotic Endoscopes

Citation

Slatkin, Andrew Brett (1999) Modeling and Experiments for a Class of Robotic Endoscopes. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/NG6V-TD44. https://resolver.caltech.edu/CaltechETD:etd-10112006-154843

Abstract

Current developments in minimally invasive medical practice motivated this study of self-propelled, robotic endoscopes for deep penetration into curved physiological lumens. The conceptual design of such devices is applicable to endoscopy within a variety of lumens in the human body, e.g., blood vessels, but the initial objective of this technology is to provide access to the interior of the entire small intestine without surgical incisions. The small intestine presents several challenges to endoscopic penetration: it is extremely compliant to applied loading, internally lubricated, easily injured, and contains many tight curves along its length of approximately eighteen feet.

This thesis reports the basic design and locomotion concepts for one class of endoscopic robots that are intended to provide safe and reliable traversal of the small intestine via worm-like actuation. Five generations of proof-of-concept prototype robots have been built to validate the fundamental concepts. Furthermore, these miniaturized robots have incorporated the following features: redundant actuation with computer control, tool-free modular assembly, and on-board videoimaging capability. The prototypes have been tested in rubber tubing, the small intestines of deceased pigs, and in the small intestines of live, anaesthetized pigs.

At the onset of this research, little regarding the elastic properties of small intestine existed in the biomechanics literature that would be applicable to the design of these mechanisms. However, accurate prediction of the small intestine's response to robotic loadings would dramatically improve the research and development process of these machines. Thus, an investigation of the elastic behavior of the small intestine commenced. Finite deformation, nonlinear, anisotropic, incompressible, viscoelastic behavior of the small intestine was studied. This soft tissue biomechanical analysis and experimentation (on living and dissected intestinal specimens) culminated with a numerical model that simulates intestinal response to the actions of a prototypical robotic component. Experiments on living specimens were performed to determine the levels of applied loadings and internal stresses that are likely to injure these fragile tissues, and the biomechanics computer modeling incorporates three distinct measures for injury potential.

Thesis Files