Teleoperated Continuum Robots in Medicine: Design, Calibration and Control Methods Enabling More Versatile and Cost-Effective Systems
AUTHORS
ABSTRACT
For several decades, engineers have sought to make surgeries safer, more accurate, less invasive and easier to perform by introducing robotic tools to the operating room. Continuum robots (flexible manipulators whose motions are often described as “snake-like”) have garnered particular interest from the medical robotics research community for their passive compliance, small achievable diameters, and ability to navigate around anatomical obstacles or through open lumens. While continuum robots hold great promise in medicine, barriers to clinical adoption remain; factors like cost, OR workflow, and the ability to use one system for a variety of clinical applications can affect whether or not a system will ultimately make its way into common use. In this dissertation, we present several new developments aimed at addressing these barriers, from the standpoint of system design, robot modeling, calibration and control. In particular, we focus on two types of robots: concentric tube robots, and soft waterjet-actuated continuum robots. A concentric tube robot is a manipulator composed of nested, needle-sized, superelastic, precurved tubes, whose relative translations and rotations produce a tentacle-like motion. We present a new modular system designed to deploy several concentric tube manipulators through the nose, which can be teleoperated by a physician to perform procedures in the sinuses, skull base, and orbits. From a design standpoint, we present new features to enable quick and easy tool changes and sterilization of tools, for a more versatile and practical system. We also propose a new clinical application for the system – removing tumors behind the eye – and demonstrate its viability in phantom models. Advances in control which enable the use of more curved tubes are used to expand the workspace of the manipulators. We then present a novel self-calibration approach for multi-arm continuum robot systems, based on randomly generated collisions between the arms, which are sensed by low-cost analog circuitry. This eliminates the need for expensive external tracking systems, reducing the overall cost and simplifying workflow. Finally, we show how the same mechanics-based modeling framework used to control these concentric tube robots can be adapted and employed to control a recently developed soft waterjet-actuated endoscope (the “Hydrojet”). The Hydrojet was designed to enable ultralow-cost gastric cancer screenings in low resource settings, and consists of a soft polymer body which bends in response to water jets sprayed from the tip of the device. We show that our modeling approach, coupled with closed-loop control, can enable accurate control and intuitive teleoperation of the device, including thorough inspection of the stomach in phantom models.
Tags: Dissertations 2022