Quasistatic Modeling of Concentric Tube Robots with External Loads.

Biomedical Engineering, Boston University, Boston, MA 02215 USA ( ).
Proceedings of the ... IEEE/RSJ International Conference on Intelligent Robots and Systems. IEEE/RSJ International Conference on Intelligent Robots and Systems 12/2010; 2010:2325-2332. DOI: 10.1109/IROS.2010.5651240
Source: PubMed


Concentric tube robots are a subset of continuum robots constructed by combining pre-curved elastic tubes. As the tubes are rotated and translated with respect to each other, their curvatures interact elastically, enabling control of the robot's tip configuration as well as the curvature along its length. This technology is projected to be useful in many types of minimally invasive medical procedures. Because these robots are flexible by design, they deflect considerably when applying forces to the external environment. Thus, in contrast to rigid-link robots, their kinematic and static force models are coupled. This paper derives a multi-tube quasistatic model that relates tube rotations and translations together with externally applied loads to robot shape and tip configuration. The model can be applied in robot design, procedure planning as well as control. For validation, the multi-tube model is compared experimentally to a computationally-efficient single-tube approximate model.

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Available from: Pierre E Dupont, Jul 06, 2015
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    • "Concentric tube robots, which are inspired by the tentacles of octopus, are a subset of continuum robots consisted of several pre-curved elastic tubes which can rotate axially and translate along their axes [1]. Because of the elastic deformation of each combining tube, the CTR is flexible and its resultant shape is determined by the pre-curvature, the stiffness ratio and the rotation and translation of the concentric tubes with respect to each other. "
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    ABSTRACT: Concentric tube robot (CTR) comprises several precurved concentric tubes which can rotate and translate independently with respect to each other. Each pre-curved tube of a CTR can be controlled to rotate axially and translate along its axis, which enables the tip to bypass obstacles and finally reach the target position. The concentric tube robots enable surgeons to perform delicate procedures by combining the flexibility of elastic catheters with the use of operation tools, such as needles, forceps and grippers. Hence, many clinical applications of concentric tube robots are promising, such as transnasal robotic neurosurgery. Concentric tube robots are suitable for such minimally invasive surgeries because they are able to present various flexible shapes with great dexterity, which strengthens the ability of collision avoidance and enlarges the reachability of operation tools. This paper describes an image based visual servoing method to control the concentric tube robot so that it can reach a desired position. A model-less control algorithm is developed by first estimating and adjusting the Jacobian matrix based on measurement of each incremental movement traced by a single camera, and then generating the next motion using the estimated Jacobian matrix. Therefore, no kinematic model is required to control the CTR during experiments and the experimental results reveal the feasibility and accuracy of the proposed method. To the best of our knowledge, this is the first work that realizes model-less feedback control of concentric tube robots based on visual servoing.
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    • "most of them deal with continuum robotic arms [11] [12] [13] [14] [15]. The UFM is modeled as a continuous beam, and the statics is based on Bernoulli-Euler Constitutive Law [12] [13] [14] or Crossrat Rod Theory [11] [15]. These models well predict the UFM backbone deformation under external loadings, and validations are given with simple loading conditions. "
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    ABSTRACT: In this paper, statics model of an underactuated wire-driven flexible robotic arm is introduced. The robotic arm is composed of a serpentine backbone and a set of controlling wires. It has decoupled bending rigidity and axial rigidity, which enables the robot large axial payload capacity. Statics model of the robotic arm is developed using the Newton-Euler method. Combined with the kinematics model, the robotic arm deformation as well as the wire motion needed to control the robotic arm can be obtained. The model is validated by experiments. Results show that, the proposed model can well predict the robotic arm bending curve. Also, the bending curve is not affected by the wire pre-tension. This enables the wire-driven robotic arm with potential applications in minimally invasive surgical operations.
    Full-text · Conference Paper · Aug 2014
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    • "Elastic models that account for tube twisting and bending , but neglect longitudinal strain and cross section shear have been demonstrated to accurately model concentric tube robots kinematics [5], [7], [18]. Following the approach of [5], a concentric tube robot T is defined as composed of n tubes with Bishop coordinate frames defined with respect to each tube. "
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    ABSTRACT: Concentric tube robots are continuum robots that can navigate natural pathways to reach locations deep inside the human body. Their operation is based on rotating and telescopically actuating concentric tubes to achieve robot tip pose control. During tube manipulation, the elastic energy stored in the robot structure may give rise to unstable robot configurations and loss of control. This can occur, in particular, for highly curved and elongated tubes that are required for certain surgical interventions. This paper presents a path planning methodology that allows the utilization of such generally unstable concentric tube robots by ensuring that they operate in their stable configuration regions.
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