Design, Modeling and Control of Continuum Robots and Dexterous Wrists with Applications to Transurethral Bladder Cancer Resection
Bladder cancer is the 4th leading cancer type in 2018 in the US male population. Staging and treatment of non-muscle-invasive bladder tumors using TURBT (Transurethral Resection of Bladder Tumors) is challenging due to limitations in tool dexterity, visualization and risk of bladder wall perforation. Currently, transurethral resection is achieved via a rigid resectoscope lacking distal dexterity necessary for a precise resection. To address these needs, an endoscopic robotic system called TURBot was developed. The first part of this dissertation addresses lack of baseline characterization of TURBT. A kinematic modeling framework is created and compared against experimental data to delineate correlations between kinematic dexterity measures and resection performance. A key outcome of this study is the identification of important dexterity measures that correlate with resection accuracy. This study presents the first quantitative benchmark for assessment of TURBT. In the second part of this dissertation, design considerations, modeling and control challenges of TURBot are addressed to enable the first robot-assisted in vivo TURBT. Successful transurethral deployment, access to the entire bladder and successful robotic ablation is verified in in vivo porcine studies. In addition, TURBot resection is compared against manual resection in a user study using a human bladder phantom. As part of this investigation, a redundancy resolution framework is proposed to mitigate the visual occlusion problem that often arises in robotic minimally invasive surgery in confined spaces. At the end, the analysis of a wrist architecture with open-ended wire routing is presented. The open-ended actuation scheme offers accuracy and robustness to wire creep thereby potentially increasing the lifespan of surgical wrists. A particular wrist with this architecture is adopted as a case study and the effects of wire forces on its characteristics are investigated. The contributions of this dissertation present fundamental steps that pave the way towards successful clinical robot-assisted TURBT. Lessons learned through the animal and the user studies as well the manual resection performance characterization inform designers of future systems for robot-assisted TURBT.