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Cenk M Cavusoglu - One of the best experts on this subject based on the ideXlab platform.

  • experimental validation of the pseudo rigid Body Model of the mri actuated catheter
    International Conference on Robotics and Automation, 2017
    Co-Authors: Tipakorn Greigarn, Russell C Jackson, Taoming Liu, Cenk M Cavusoglu
    Abstract:

    An MRI-actuated catheter is a novel robotic catheter system that utilizes the MRI for both remote steering and visualization for catheter ablation of atrial fibrillation. Planning and control of the catheter requires a sufficiently fast yet accurate Model of the catheter. The pseudo-rigid-Body (PRB) Model offers a reasonable trade-off between speed and accuracy by approximating the continuum catheter as rigid links connected by flexible joints, thus reducing the infinite degrees of freedom of the continuum mechanism to a finite one. In this paper, a PRB Model of the MRI-actuated catheter is validated experimentally by comparing the deflections of the PRB Model with the deflections of the catheter prototype.

  • pseudo rigid Body Model and kinematic analysis of mri actuated catheters
    International Conference on Robotics and Automation, 2015
    Co-Authors: Tipakorn Greigarn, Cenk M Cavusoglu
    Abstract:

    This paper presents a kinematic study of a pseudo-rigid-Body Model (PRBM) of MRI-compatible, magnetically actuated, steerable catheters. It includes a derivation of a mathematical Model of the PRBM of the catheter, singularity studies of the Model, and a new manipulability measure. While the forward kinematics of the Model presented here is applicable to PRBMs for other applications, actuation method is unique to the particular design. Hence, a careful study of singularities and manipulability of the Model is required. The singularities are studied from the underlying equations of motion with intuitive interpretations. The proposed manipulability measure is a generalization of the inverse condition number manipulability measure of robotic manipulators. While the PRBM is an approximation of the flexible catheter, kinematic studies of the PRBM still provide some insight into feasibility and limitations of the catheter, which is beneficial to the design and motion planning of the catheter.

Dimitri Metaxas - One of the best experts on this subject based on the ideXlab platform.

  • Three-Dimensional Human Body Model Acquisition from Multiple Views
    International Journal of Computer Vision, 1998
    Co-Authors: Ioannis A. Kakadiaris, Dimitri Metaxas
    Abstract:

    We present a novel approach to the three-dimensional human Body Model acquisition from three mutually orthogonal views. Our technique is based on the spatiotemporal analysis of the deforming apparent contour of a human moving according to a protocol of movements. For generality and robustness our technique does not use a prior Model of the human Body and a prior Body part segmentation is not assumed. Therefore, our technique applies to humans of any anthropometric dimension. To parameterize and segment over time a deforming apparent contour, we introduce a new shape representation technique based on primitive composition . The composed deformable Model allows us to represent large local deformations and their evolution in a compact and intuitive way. In addition, this representation allows us to hypothesize an underlying part structure and test this hypothesis against the relative motion (due to forces exerted from the image data) of the defining primitives of the composed Model. Furthermore, we develop a Human Body Part Decomposition Algorithm (HBPDA) that recovers all the Body parts of a subject by monitoring the changes over time to the shape of the deforming silhouette. In addition, we modularize the process of simultaneous two-dimensional part determination and shape estimation by employing the Supervisory Control Theory of Discrete Event Systems . Finally, we present a novel algorithm which selectively integrates the (segmented by the HBPDA) apparent contours from three mutually orthogonal viewpoints to obtain a three-dimensional Model of the subject's Body parts. The effectiveness of the approach is demonstrated through a series of experiments where a subject performs a set of movements according to a protocol that reveals the structure of the human Body.

  • 3d human Body Model acquisition from multiple views
    International Conference on Computer Vision, 1995
    Co-Authors: Ioannis A. Kakadiaris, Dimitri Metaxas
    Abstract:

    We present a novel motion-based approach for the part determination and shape estimation of a human's Body parts. The novelty of the technique is that neither a prior Model of the human Body is employed nor prior Body part segmentation is assumed. We present a human Body part identification strategy (HBPIS) that recovers all the Body parts of a moving human based on the spatiotemporal analysis of its deforming silhouette. We formalize the process of simultaneous part determination and 2D shape estimation by employing the supervisory control theory of discrete event systems. In addition, in order to acquire the 3D shape of the Body parts, we present a new algorithm which selectively integrates the (segmented by the HBPIS) apparent contours, from three mutually orthogonal views. The effectiveness of the approach is demonstrated through a series of experiments, where a subject performs a set of movements according to a protocol that reveals the structure of the human Body. >

Larry L. Howell - One of the best experts on this subject based on the ideXlab platform.

  • a pseudo rigid Body Model of the human spine to predict implant induced changes on motion
    Journal of Mechanisms and Robotics, 2011
    Co-Authors: Peter A Halverson, Anton E. Bowden, Larry L. Howell
    Abstract:

    Injury, instrumentation, or surgery may change the functional biomechanics of the spine. Adverse changes at one level may affect the adjacent levels. Modeling these changes can increase the understanding of adjacent-level effects and may help in the creation of devices that minimize adverse outcomes. The current Modeling techniques (e.g., animal Models, in vitro testing, and finite element analysis) used to analyze these effects are costly and are not readily accessible to the clinician. It is proposed that the pseudo-rigid-Body Model(PRBM) may be used to accurately predict adjacent level effects in a quick and cost effective manner that may lend itself to a clinically relevant tool for identifying the adjacent-level effects of various treatment options for patients with complex surgical indications. A PRBM of the lumbar spine (lower back) was developed using a compliant mechanism analysis approach. The global moment-rotation response, relative motion, and local moment-rotation response of a cadaveric specimen were determined through experimental testing under three conditions: intact, fused, and implanted with a prototype total disc replacement. The spine was Modeled using the PRBM and compared with the values obtained through in-vitro testing for the three cases. The PRBM accurately predicted the moment-rotation response of the entire specimen. Additionally, the PRBM predicted changes in relative motion patterns of the specimen. The resulting Models show particular promise in evaluating various procedures and implants in a clinical setting and in the early stage design process.

  • A Pseudo-Rigid-Body Model for Large Deflections of Fixed-Clamped Carbon Nanotubes
    Journal of Mechanisms and Robotics, 2010
    Co-Authors: Larry L. Howell, Christopher Dibiasio, Michael A. Cullinan, Robert M. Panas, Martin L. Culpepper
    Abstract:

    Carbon nanotubes (CNTs) may be used to create nanoscale compliant mechanisms that possess large ranges of motion relative to their device size. Many macroscale compliant mechanisms contain compliant elements that are subjected to fixed-clamped boundary conditions, indicating that they may be of value in nanoscale design. The combination of boundary conditions and large strains yield deformations at the tube ends and strain stiffening along the length of the tube, which are not observed in macroscale analogs. The large-deflection behavior of a fixedclamped CNT is not well-predicted by macroscale large-deflection beam bending Models or truss Models. Herein, we show that a pseudo-rigid-Body Model may be adapted to capture the strain stiffening behavior and, thereby, predict a CNT’s fixed-clamped behavior with less than 3% error from molecular simulations. The resulting pseudo-rigid-Body Model may be used to set initial design parameters for CNT-based compliant mechanisms. This removes the need for iterative, time-intensive molecular simulations during initial design phases. DOI: 10.1115/1.4001726

  • comparison of molecular simulation and pseudo rigid Body Model predictions for a carbon nanotube based compliant parallel guiding mechanism
    Journal of Mechanical Design, 2008
    Co-Authors: Christopher Dibiasio, Larry L. Howell, Robert M. Panas, Martin L. Culpepper, Spencer P Magleby
    Abstract:

    We report on the accuracy of the pseudo-rigid-Body Model (PRBM) in predicting the behavior of a nanoscale parallel-guiding mechanism (nPGM) that uses two single-walled (5,5) carbon nanotubes (CNTs) as the flexural guiding elements. The nPGM has two regions of behavior: region I is governed by the bulk deformation of the nanotubes, and region 2 is characterized by hingelike flexing of four "kinks" that occur due to buckling of the nanotube walls. PRBM parameters for (5,5) CNTs are proposed. Molecular simulation results of region I behavior match PRBM predictions of (I) kinematic behavior with less than 7.3% error and (2) elastomechanic behavior with less than 5.7% error. Although region I is of more interest because of its well-defined and stable nature, region 2 motion is also investigated. We show that the PRBM parameters are dependent on the selection of the effective tube thickness and moment of inertia, the lesson being that designers must take care to consider the thickness and moment of inertia values when deriving PRBM constants.

  • Dynamic Modeling of Compliant Mechanisms Based on the Pseudo-Rigid-Body Model
    Journal of Mechanical Design, 2005
    Co-Authors: Larry L. Howell, Craig P. Lusk, Ying Yue
    Abstract:

    Based on the principle of dynamic equivalence, a new dynamic Model of compliant mechanisms is developed using the pseudo-rigid-Body Model. The dynamic equation of general planar compliant mechanisms is derived. The natural frequency of a compliant mechanism is obtained in the example of a planar compliant parallel-guiding mechanism. The numerical results show the effectiveness and advantage of the proposed method compared with the methods of FEA and flexible mechanisms.

  • Development of Commercially Viable Compliant Mechanisms Using the Pseudo-Rigid-Body Model: Case Studies of Parallel Mechanisms
    Journal of Intelligent Material Systems and Structures, 2004
    Co-Authors: Christopher A. Mattson, Larry L. Howell, Spencer P Magleby
    Abstract:

    Analysis and synthesis of compliant mechanisms has recently been the subject of significant study in the research community. This focus has led to a number of design approaches for developing compliant mechanisms. This paper describes the value of using the Pseudo-Rigid-Body Model (PRBM) to design compliant mechanisms for commercial products. Application of the PRBM is illustrated through the development of two parallel mechanisms: a bicycle derailleur and parallel-motion bicycle brakes. The PRBM allows compliant mechanisms to be Modeled and analyzed as rigid-Body mechanisms and significantly reduces the complexity of analysis. Mechanisms with straightforward properties are used to demonstrate the use of the PRBM to design commercially viable compliant mechanisms for required motion and force-deflection characteristics.

Tipakorn Greigarn - One of the best experts on this subject based on the ideXlab platform.

  • experimental validation of the pseudo rigid Body Model of the mri actuated catheter
    International Conference on Robotics and Automation, 2017
    Co-Authors: Tipakorn Greigarn, Russell C Jackson, Taoming Liu, Cenk M Cavusoglu
    Abstract:

    An MRI-actuated catheter is a novel robotic catheter system that utilizes the MRI for both remote steering and visualization for catheter ablation of atrial fibrillation. Planning and control of the catheter requires a sufficiently fast yet accurate Model of the catheter. The pseudo-rigid-Body (PRB) Model offers a reasonable trade-off between speed and accuracy by approximating the continuum catheter as rigid links connected by flexible joints, thus reducing the infinite degrees of freedom of the continuum mechanism to a finite one. In this paper, a PRB Model of the MRI-actuated catheter is validated experimentally by comparing the deflections of the PRB Model with the deflections of the catheter prototype.

  • pseudo rigid Body Model and kinematic analysis of mri actuated catheters
    International Conference on Robotics and Automation, 2015
    Co-Authors: Tipakorn Greigarn, Cenk M Cavusoglu
    Abstract:

    This paper presents a kinematic study of a pseudo-rigid-Body Model (PRBM) of MRI-compatible, magnetically actuated, steerable catheters. It includes a derivation of a mathematical Model of the PRBM of the catheter, singularity studies of the Model, and a new manipulability measure. While the forward kinematics of the Model presented here is applicable to PRBMs for other applications, actuation method is unique to the particular design. Hence, a careful study of singularities and manipulability of the Model is required. The singularities are studied from the underlying equations of motion with intuitive interpretations. The proposed manipulability measure is a generalization of the inverse condition number manipulability measure of robotic manipulators. While the PRBM is an approximation of the flexible catheter, kinematic studies of the PRBM still provide some insight into feasibility and limitations of the catheter, which is beneficial to the design and motion planning of the catheter.

Ioannis A. Kakadiaris - One of the best experts on this subject based on the ideXlab platform.

  • Three-Dimensional Human Body Model Acquisition from Multiple Views
    International Journal of Computer Vision, 1998
    Co-Authors: Ioannis A. Kakadiaris, Dimitri Metaxas
    Abstract:

    We present a novel approach to the three-dimensional human Body Model acquisition from three mutually orthogonal views. Our technique is based on the spatiotemporal analysis of the deforming apparent contour of a human moving according to a protocol of movements. For generality and robustness our technique does not use a prior Model of the human Body and a prior Body part segmentation is not assumed. Therefore, our technique applies to humans of any anthropometric dimension. To parameterize and segment over time a deforming apparent contour, we introduce a new shape representation technique based on primitive composition . The composed deformable Model allows us to represent large local deformations and their evolution in a compact and intuitive way. In addition, this representation allows us to hypothesize an underlying part structure and test this hypothesis against the relative motion (due to forces exerted from the image data) of the defining primitives of the composed Model. Furthermore, we develop a Human Body Part Decomposition Algorithm (HBPDA) that recovers all the Body parts of a subject by monitoring the changes over time to the shape of the deforming silhouette. In addition, we modularize the process of simultaneous two-dimensional part determination and shape estimation by employing the Supervisory Control Theory of Discrete Event Systems . Finally, we present a novel algorithm which selectively integrates the (segmented by the HBPDA) apparent contours from three mutually orthogonal viewpoints to obtain a three-dimensional Model of the subject's Body parts. The effectiveness of the approach is demonstrated through a series of experiments where a subject performs a set of movements according to a protocol that reveals the structure of the human Body.

  • 3d human Body Model acquisition from multiple views
    International Conference on Computer Vision, 1995
    Co-Authors: Ioannis A. Kakadiaris, Dimitri Metaxas
    Abstract:

    We present a novel motion-based approach for the part determination and shape estimation of a human's Body parts. The novelty of the technique is that neither a prior Model of the human Body is employed nor prior Body part segmentation is assumed. We present a human Body part identification strategy (HBPIS) that recovers all the Body parts of a moving human based on the spatiotemporal analysis of its deforming silhouette. We formalize the process of simultaneous part determination and 2D shape estimation by employing the supervisory control theory of discrete event systems. In addition, in order to acquire the 3D shape of the Body parts, we present a new algorithm which selectively integrates the (segmented by the HBPIS) apparent contours, from three mutually orthogonal views. The effectiveness of the approach is demonstrated through a series of experiments, where a subject performs a set of movements according to a protocol that reveals the structure of the human Body. >