BioE MS Thesis Presentation- Chenyu GU

Committee members:

Dr. Jaydev Desai, Department of Biomedical Engineering, Georgia Institute of Technology

Dr. Omer Inan, School of Electrical and Computer Engineering, Georgia Institute of Technology

Dr. Yue Chen, Department of Biomedical Engineering, Georgia Institute of Technology

Design, Modeling, and Control of a Polymer-Based Continuum Robot

Minimally Invasive Surgery (MIS) is preferred over open surgery because it reduces patient trauma, shortens recovery time, and lowers the risk of complications. However, current MIS tools are typically passive and provide limited dexterity, making it difficult to access target locations within complex and tortuous anatomical structures. To address this limitation, this thesis presents the design of a meso-scale Hydraulic Polymer-based Continuum Robot (HyPo-CR) capable of achieving large, smooth bending motions. The proposed robot has an outer diameter of 2.14 mm and consists of a radially reinforced hydraulic actuator embedded within a laser-micromachined polyimide (PI) tube. Routing blocks are incorporated along the structure to maintain actuator alignment and improve force transmission. To better understand the mechanical behavior, three different design configurations are developed and experimentally evaluated, where the proposed design demonstrates improved planar bending and reduces undesired twisting by up to 58.8% compared to alternative designs. Furthermore, the robot is demonstrated in a two dimensional (2D) aortic arch phantom, where it successfully navigates through confined pathways and achieves bending angles greater than 180◦.To model the nonlinear behavior of the system, a Preisach hysteresis model is used to describe the relationship between the actuation force and the resulting tip deflection, achieving a validation error of 2.26◦. Since accurate knowledge of the robot configuration is critical for control, this work also investigates shape sensing methods. A camera-based approach is first implemented to provide high-resolution reference measurements of the robot shape. To enable more compact and practical sensing, an embedded Direct Laser Writing (DLW)-based resistive strain sensor is developed on the PI tube, along with an amplification circuit and a polynomial model to estimate the bending angle in real time. Building upon the modeling and sensing framework, both open-loop and closed-loop control strategies are implemented. These results demonstrate the potential of the proposed system for MIS applications and provide a foundation for future development of smaller-scale robotic guidewires and micro-catheters with integrated sensing and control capabilities.