Design and Control of Concentric-Tube Robots

Abstract

A novel approach toward construction of robots is based on a concentric combination of precurved elastic tubes. By rotation and extension of the tubes with respect to each other, their curvatures interact elastically to position and orient the robot's tip, as well as to control the robot's shape along its length. In this approach, the flexible tubes comprise both the links and the joints of the robot. Since the actuators attach to the tubes at their proximal ends, the robot itself forms a slender curve that is well suited for minimally invasive medical procedures. This paper demonstrates the potential of this technology. Design principles are presented and a general kinematic model incorporating tube bending and torsion is derived. Experimental demonstration of real-time position control using this model is also described.

Implicit active constraints for safe and effective guidance of unstable concentric tube robots

“…Independently translating robot sections can comprise either one or two tubes, forming constant, or variable curvature sections [7]. The translation of tube i is denoted as i ϕ, and its rotation at the base as i α B .…”

“…CTR mechanics have thus far been investigated extensively, with reliable models existing for torsionally compliant kinematics and equilibrium conformations [7], [8]. The latter result from the instability of CTR, which under certain configurations rapidly release energy after sufficient torsional wind-up of their tubular components [9].…”

“…Using collaborative control deep seated targets are reached safe and efficiently. to achieve real-time performance for inverse kinematics include root-finding and look-up tables [7], and jacobianbased approximations [14], sparse path-plans using rapidlyexploring-random trees for pre-defined targets [15], and precalculation of dense-path plans for the robot workspace [16], [17]. The latter contribution allows interactive rate motion planning, but does not consider robot instability.…”

Hysteresis analysis of a notched continuum manipulator driven by tendon

“…Simaan and Taylor (2004) designed a tendon-driven continuum manipulator which contains several elastic continuum backbones and spacer disks. Webster et al (2007) and Dupont et al (2010) presented a concentric tube manipulator comprising several nested pre-curved tubes. Li and Du (2013) proposed a continuum manipulator which consists of multiple section set backbones composed of short links.…”

Safe Motion Planning for Imprecise Robotic Manipulators by Minimizing Probability of Collision

“…Home assistance robotic manipulators must feature compliant joints for safety and must be lower cost to spur adoption, which results in decreased precision of sensors and actuators. Medical robots, such as tentacle-like and snake-like robots (e.g., [32,9,23,7]), are becoming smaller and also are gaining larger numbers of degrees of freedom. These features are necessary to enable new, less invasive surgical procedures that require maneuvering around sensitive or impenetrable anatomical obstacles.…”