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GRASP Lab Seminar 2003-2004
February 27, 11:00 AM, Levine Hall 307, hosted by Vijay Kumar.
Jaydev Desai
Drexel University
Reality-Based Modeling of Tool-tissue Interaction for Robot-Assisted Surgery
Abstract: Reality-based modeling of tool-tissue interaction in surgery is a key requirement for developing an enhanced haptic and vision based display for minimally invasive surgical training and simulation. In reality-based modeling, we are interested in modeling tissues as accurately as possible by determining the mechanical properties experimentally and developing a predictive model that is self consistent with the experimentally-determined properties. In this research, we focus on soft tissue modeling for interaction with the liver during probing and cutting tasks. From liver probing experiments, we have developed a hybrid one-dimensional liver model derived from a series of indentation experiments, which is valid in both low strain and large strain regions. We have designed and developed a tissue indentation equipment for characterizing the biomechanical properties of liver and developing our theoretical model. For probing studies, the pig liver is simplified as the incompressible, isotropic, and homogeneous elastic material. This model is the basis for our initial finite element model of the pig liver.
For liver cutting experiments, we have newly developed hardware and software to characterize the mechanical response of pig liver during (ex-vivo) cutting. We have designed a custom-made cutting machine and a data acquisition system to analyze the characteristics of the cutting force versus displacement plot. The primary results of the force-displacement data reveals that the cutting process consists of a sequence of intermittent localized fracture (localized crack extension in the tissue). The macroscopic cutting force-displacement curve shows repeating self-similar units of localized linear loading followed by sudden unloading. The sudden unloading coincides with onset of localized crack growth. This experimental data was used to determine the self-consistent local effective Young's modulus of the specimen to be used in finite element models. Results from plane-stress and plane-strain finite element analyses revealed that the magnitude of the self-consistent local effective Young's modulus varied within close bounds.Biography: Jaydev P. Desai is an Assistant Professor in the Department of Mechanical Engineering and Mechanics at Drexel University and leads the Program for Robotics, Intelligent Sensing, and Mechatronics (PRISM) Laboratory. He also holds joint appointments with the Department of Cardiovascular Medicine and Surgery at Drexel University College of Medicine and the Department of Materials Engineering at Drexel University. He received his M.S. in Mechanical Engineering and Applied Mechanics, M.A. in Mathematics, and Ph.D. in Mechanical Engineering and Applied Mechanics, all from the University of Pennsylvania in 1995, 1997, and 1998 respectively. He completed his undergraduate studies from the Indian Institute of Technology, Bombay in 1993. Prior to joining Drexel University in the Fall of 1999, he was a Post-Doctoral Fellow in the Division of Engineering and Applied Sciences at Harvard University. He is also a recipient of the 2002 NSF CAREER award. His research interests include reality-based modeling of soft tissue interaction for robot-assisted surgery, surgical simulation, model-based teleoperation, and modeling and control of robot manipulators.
