Bezier Spline

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Max J. Ammann - One of the best experts on this subject based on the ideXlab platform.

  • Optimized Monopole and Dipole Antennas for UWB Asset Tag Location Systems
    IEEE Transactions on Antennas and Propagation, 2012
    Co-Authors: Antoine Dumoulin, Matthias John, Max J. Ammann, Patrick Mcevoy
    Abstract:

    Miniaturized monopole and dipole antenna designs are reported with performances optimized for ultrawideband pulsed radio applications. The geometries are created using Bezier Spline shapes, which have been refined with a genetic algorithm to simultaneously take account of both frequency- and time-domain criteria. Time-domain measurements of ultra wideband antennas with uniformly distributed energy across the full 3.1-10.6 GHz mask are reported for the first time and validate a new approach to minimization of pulse dispersion effects in the antenna designs.

  • Spatial group delay patterns for three ultra wideband Spline antennas
    2008 IEEE Antennas and Propagation Society International Symposium, 2008
    Co-Authors: Patrick Mcevoy, Matthias John, Sergio Curto, Max J. Ammann
    Abstract:

    The IEEE ultra wideband (UWB) standard includes both a multiple frequency carrier (MB-OFDM) and an impulse spectrum (DS-UWB) method, for which application antennas should be appropriately optimized. Small printed monopoles with outline features that can be defined by a Bezier-Spline [1] have good matched impedance performance across the 3.1 - 10.6 GHz band. For communications applications, an omni-directional pattern, where the gain pattern varies by less than plusmn5 dBi, and a stable frequency-gain profile in the azimuth plane, allow for an even spatial coverage in all directions. In the case of an impulse system, any non-linear phase transfer performance in the antenna adds distortion to the transieved pulses therefore reducing the data rates. Contemporary UWB antenna gain performances are often presented across the whole spectrum using contour plots. This discloses more details and compliments the conventional sampled frequency polar plots that are more suited to narrow bandwidth antennas. In this paper, the approach is extended to a group delay pattern measurement which is more comprehensive than the traditional and limited boresight-only approach.

  • Group delay performance of ultra wideband monopole antennas for communication applications
    2008 Loughborough Antennas and Propagation Conference, 2008
    Co-Authors: Patrick Mcevoy, Matthias John, Sergio Curto, Max J. Ammann
    Abstract:

    While limited in dimensions, the shape of small ultra wideband (UWB) antennas can significantly impact on the required gain pattern stablity and the inherent impulse spreading throughout the bandwidth. The comparative gain performance of a square monopole and two Bezier-Spline shaped monopoles (optimised for low insertion losses on small groundplanes) as portable UWB device antennas solutions are reported. By measuring the transmission group delay for the three geometries in paired combinations, the time-domain spreading due to each individual antenna is solved numerically with a system of equations.

  • Spline based geometry for printed UWB antenna design
    2007 IEEE Antennas and Propagation Society International Symposium, 2007
    Co-Authors: Matthias John, Max J. Ammann
    Abstract:

    This paper presents a geometry for ultra-wideband (UWB) antennas which is based on quadratic Bezier Spline curves. A genetic algorithm (GA) is used to optimise the geometry. The search space for the GA is minimised in order to improve the performance and computational efficiency of the algorithm. The optimised antenna covers the entire UWB bandwidth.

  • Spline-based geometry for printed monopole antennas
    Electronics Letters, 2007
    Co-Authors: Matthias John, Max J. Ammann
    Abstract:

    A novel Bezier Spline-based geometry for printed monopole antennas is presented. Quadratic curves are used to describe the outline of the radiating element. The geometry is optimised by a genetic algorithm. A small number of control points are used to define the geometry, ensuring a small search space for the GA. The resulting antenna has an impedance bandwidth from 1.44 to 14.7 GHz

Li Xiaopeng - One of the best experts on this subject based on the ideXlab platform.

  • Research on control method of drill pipe assembling and discharge robot based on neural network and Bezier Spline trajectory planning
    2018 13th IEEE Conference on Industrial Electronics and Applications (ICIEA), 2018
    Co-Authors: Han Xiangdong, Chen Naijian, Sun Jianbo, Li Xiaopeng
    Abstract:

    The existing rig work has the following characteristics: tedious operation, high repetition rate, poor efficiency, the number of carrying bar is not enough automatic drill pipe changer device. A drill pipe changer device is proposed and designed, which is applied to the industrial robot technology to achieve assemble and discharge of drill pipe. Deriving the mathematical solution of its positive solution, the inverse solution for the designed robot. Its work process requirements and path planning were analyzed, using five Time Bezier Spline curve. Designing a PID controller based on neural network; and finally validating the validity of the trajectory planning method and control strategy by experiments.

Matthias John - One of the best experts on this subject based on the ideXlab platform.

  • Optimized Monopole and Dipole Antennas for UWB Asset Tag Location Systems
    IEEE Transactions on Antennas and Propagation, 2012
    Co-Authors: Antoine Dumoulin, Matthias John, Max J. Ammann, Patrick Mcevoy
    Abstract:

    Miniaturized monopole and dipole antenna designs are reported with performances optimized for ultrawideband pulsed radio applications. The geometries are created using Bezier Spline shapes, which have been refined with a genetic algorithm to simultaneously take account of both frequency- and time-domain criteria. Time-domain measurements of ultra wideband antennas with uniformly distributed energy across the full 3.1-10.6 GHz mask are reported for the first time and validate a new approach to minimization of pulse dispersion effects in the antenna designs.

  • Spatial group delay patterns for three ultra wideband Spline antennas
    2008 IEEE Antennas and Propagation Society International Symposium, 2008
    Co-Authors: Patrick Mcevoy, Matthias John, Sergio Curto, Max J. Ammann
    Abstract:

    The IEEE ultra wideband (UWB) standard includes both a multiple frequency carrier (MB-OFDM) and an impulse spectrum (DS-UWB) method, for which application antennas should be appropriately optimized. Small printed monopoles with outline features that can be defined by a Bezier-Spline [1] have good matched impedance performance across the 3.1 - 10.6 GHz band. For communications applications, an omni-directional pattern, where the gain pattern varies by less than plusmn5 dBi, and a stable frequency-gain profile in the azimuth plane, allow for an even spatial coverage in all directions. In the case of an impulse system, any non-linear phase transfer performance in the antenna adds distortion to the transieved pulses therefore reducing the data rates. Contemporary UWB antenna gain performances are often presented across the whole spectrum using contour plots. This discloses more details and compliments the conventional sampled frequency polar plots that are more suited to narrow bandwidth antennas. In this paper, the approach is extended to a group delay pattern measurement which is more comprehensive than the traditional and limited boresight-only approach.

  • Group delay performance of ultra wideband monopole antennas for communication applications
    2008 Loughborough Antennas and Propagation Conference, 2008
    Co-Authors: Patrick Mcevoy, Matthias John, Sergio Curto, Max J. Ammann
    Abstract:

    While limited in dimensions, the shape of small ultra wideband (UWB) antennas can significantly impact on the required gain pattern stablity and the inherent impulse spreading throughout the bandwidth. The comparative gain performance of a square monopole and two Bezier-Spline shaped monopoles (optimised for low insertion losses on small groundplanes) as portable UWB device antennas solutions are reported. By measuring the transmission group delay for the three geometries in paired combinations, the time-domain spreading due to each individual antenna is solved numerically with a system of equations.

  • Spline based geometry for printed UWB antenna design
    2007 IEEE Antennas and Propagation Society International Symposium, 2007
    Co-Authors: Matthias John, Max J. Ammann
    Abstract:

    This paper presents a geometry for ultra-wideband (UWB) antennas which is based on quadratic Bezier Spline curves. A genetic algorithm (GA) is used to optimise the geometry. The search space for the GA is minimised in order to improve the performance and computational efficiency of the algorithm. The optimised antenna covers the entire UWB bandwidth.

  • Spline-based geometry for printed monopole antennas
    Electronics Letters, 2007
    Co-Authors: Matthias John, Max J. Ammann
    Abstract:

    A novel Bezier Spline-based geometry for printed monopole antennas is presented. Quadratic curves are used to describe the outline of the radiating element. The geometry is optimised by a genetic algorithm. A small number of control points are used to define the geometry, ensuring a small search space for the GA. The resulting antenna has an impedance bandwidth from 1.44 to 14.7 GHz

Johannes Fauser - One of the best experts on this subject based on the ideXlab platform.

  • optimizing clearance of Bezier Spline trajectories for minimally invasive surgery
    Medical Image Computing and Computer-Assisted Intervention, 2019
    Co-Authors: Johannes Fauser, I Stenin, Julia Kristin, T Klenzner, Jorg Schipper, Anirban Mukhopadhyay
    Abstract:

    Preoperative planning of nonlinear trajectories is a key element in minimally-invasive surgery. Interpolating between start and goal of an intervention while circumnavigating risk structures provides the necessary feasible solutions for such procedure. While recent research shows that Rapidly-exploring Random Trees (RRT) on Bezier Splines efficiently solve this task, access paths computed by this method do not provide optimal clearance to surrounding anatomy. We propose an approach based on sequential convex optimization that rearranges Bezier Splines computed by an RRT-connect, thereby achieving locally optimal clearance to risk structures. Experiments on real CT data of patients demonstrate the applicability of our approach on two scenarios: catheter insertion through the aorta and temporal bone surgery. We compare distances to risk structures along computed trajectories with the state of the art solution and show that our method results in clinically safer paths.

  • planning for flexible surgical robots via Bezier Spline translation
    International Conference on Robotics and Automation, 2019
    Co-Authors: Johannes Fauser, Romol Chadda, Yannik Goergen, Markus Hessinger, Paul Motzki, I Stenin, Julia Kristin, T Klenzner, Jorg Schipper, Stefan Seelecke
    Abstract:

    In a minimally invasive surgery, new flexible instruments enable safer and easier access to difficult-to-reach anatomical regions. However, their introduction into the clinical workflow requires robust replanning because navigation errors during surgery render initially planned trajectories infeasible. Such replanning requires to regularly solve an expensive two-point boundary value problem (BVP) that connects the target pose of the instrument with the currently measured one. We propose a hybrid planning scheme that features both robust and safe replanning. This two-step approach first solves the BVP and then transforms the result to circular arcs that fit the motion of our instruments’ models. We exploit implicitly defined Bezier Splines as a robust method for interpolation in the first step. A novel geometric translation of these Splines, then, provides a convenient solution for movement along circular arcs. We consider two example applications: 1) planning for a drilling unit in temporal bone surgery; and 2) guidewires in catheter insertion. Evaluation on real patient data of both temporal bone and aorta show that our proposed hybrid two-step approach achieves, on average, ${\text{55}\%}$ higher replanning rates and provides ${\text{31}\%}$ larger clearance to risk structures, thus improving trajectory quality with regard to clinical safety.

Xiaoping Qian - One of the best experts on this subject based on the ideXlab platform.

  • continuity and convergence in rational triangular Bezier Spline based isogeometric analysis
    Computer Methods in Applied Mechanics and Engineering, 2015
    Co-Authors: Xilu Wang, Xiaoping Qian
    Abstract:

    Abstract This paper presents a method for isogeometric analysis using rational Triangular Bezier Splines (rTBS) where optimal convergence rates are achieved. In this method, both the geometry and the physical field are represented by bivariate Splines in Bernstein Bezier form over the triangulation of a domain. From a given physical domain bounded by NURBS curves, a parametric domain and its triangulation are constructed. By imposing continuity constraints on Bezier ordinates, we obtain a set of global C r smooth basis functions. Convergence analysis shows that isogeometric analysis with such C r rTBS basis can deliver the optimal rate of convergence provided that the C r geometric map remains unchanged during the refinement process. This condition can be satisfied by constructing a pre-refinement geometric map that is sufficiently smooth. Numerical experiments verify that optimal rates of convergence are achieved for Poisson and linear elasticity problems.