Photoelastic Stress Analysis Error Quantification in Vasculature Models for Robot Feedback Control

Abstract-Real-time and accurate stress calculation in walls of vasculature is desired to provide catheter insertion robots of feedback control without changing the catheter stiffness and lumen. This feedback source has also applications in endovascular surgery simulation for human skills and medical tools evaluation. For that purpose we consider photoelastic effect, as birefringence produced by light retardation relates with the stress inside the photoelastic materials. In this research a polariscope was designed for urethane elastomer vasculature models, the photoelastic coefficient of urethane elastomer was measured, and the camera system was calibrated to quantify and reduce error of the measurement system. An average error of 3.6% was found for the pressure range of 70-189 mmHg inside the model of urethane elastomer, this enables to calculate accurately stress in vasculature models during Human Blood Pressure Simulation (HBPS). That way we will be able to compare in a closed loop stress produced by HBPS and by the catheter motion when manipulated by a robot. I. INTRODUCTION RAINING with simulators reduces risks of injury and costs during practice for minimally invasive surgery C. Tercero is with Nagoya University, Aiichi-ken Nagoya-shi Chikusa-ku Furo-cho 1, 464-8603 JAPAN (phone: +81-52-788-6013; fax: +81-52-788-6013; e-mail: [email protected]). S. Ikeda is with Nagoya University, Aiichi-ken Nagoya-shi Chikusa-ku Furo-cho 1, 464-8603 JAPAN (phone: +81-52-788-6013; fax: +81-52-788-6013; e-mail: ikeda @robo.mein.nagoya-u.ac.jp). In previous studies photoelastic effect was used with a catheter insertion robot to evaluate catheters In this research we will present a calibration method for the transmittance equation to measure the optical path length, a polariscope designed for our simulation purpose, the deduction of the photoelastic coefficient of urethane elastomer, and the normalization parameters calibration to calculate the principal component of stress in the vasculature model with an inner pressure range of 40-189mmHg. It is desirable to measure stress with an error below 5% for the HBPS range, to use it as reference for control loop illustrated in figure 2. Photoelastic Stress Analysis Error Quantification i

PHYSICAL MODELING OF THE KRAUKLIS WAVES: INSIGHTS FROM TWO EXPERIMENTAL APPARATUSES

Fractures play an important role in the geological related processes such as hydraulic fracturing, water-water disposal, and volcanic earthquake. Seismic waves can provide useful information from fractures at a relatively low cost. In particular, the acoustic property of fractures containing magmatic or hydrothermal fluids can provide useful information about the fracture size and the fluid composition within the fracture. For instance, in volcanology, the resonant frequency of long-period events that are linked to crack interface waves is used to obtain fluid properties of cracks in magmatic systems. However, in order to rely on seismic data, they should be precisely characterized in advance. Experimental studies are one of the most important resources to describe and understand physical systems. They are even used to validate analytical and numerical methods. In this dissertation, I aim to gain more insight into the crack waves that are slow guided waves in fluid-filled fractures and are characterized by their dispersive and resonating nature. We will develop two experimental setups. Using the first apparatus that employs the photoelasticity technique, we will visualize the stress regime of the fracture due to the motion, transmission, and reflection pattern of the crack wave. Using the second apparatus which is an acoustic data acquisition system, we extend the fracture of two parallel plates to a more complex and realistic fracture by modifying the fracture stiffness, saturated fluid and fracture geometry, and fracture surface roughness. We evaluate the dispersion and resonance properties of the crack waves under different environments. In addition, some present analytical and numerical models will be evaluated