Continuum robots can traverse anatomical pathways to intervene in regions deep inside the human body. They are able to steer along 3D curves in confined spaces and dexterously handle tissues. Concentric tube robots (CTRs) are continuum robots that comprise a series of precurved elastic tubes that can be translated and rotated with respect to each other to control the shape of the robot and tip pose. CTRs are a rapidly maturing technology that has seen extensive research over the past decade. Today, they are being evaluated as tools for a variety of surgical applications, as they can offer precision and manipulability in tight workspaces. This review provides an exhaustive classification of research on CTRs based on their clinical applications and highlights approaches for modeling, control, design, and sensing. Competing approaches are critically presented, leading to a discussion of future directions to address the limitations of current research and its translation to clinical applications. Expected final online publication date for the Annual Review of Control, Robotics, and Autonomous Systems, Volume 5 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

The dominant visual servoing approaches in Minimally Invasive Surgery (MIS) follow single points or adapt the endoscope’s field of view based on the surgical tools’ distance. These methods rely on point positions with respect to the camera frame to infer a control policy. Deviating from the dominant methods, we formulate a robotic controller that allows for image-based visual servoing that requires neither explicit tool and camera positions nor any explicit image depth information. The proposed method relies on homography-based image registration, which changes the automation paradigm from point-centric towards surgical-scene-centric approach. It simultaneously respects a programmable Remote Center of Motion (RCM). Our approach allows a surgeon to build a graph of desired views, from which, once built, views can be manually selected and automatically servoed to irrespective of robot-patient frame transformation changes. We evaluate our method on an abdominal phantom and provide an open source ROS Moveit integration for use with any serial manipulator 3 . A video is provided 4 .