New uniform grids on the sphere

Rosca, Daniela

doi:10.1051/0004-6361/201015278

Cited by 41 publications

(28 citation statements)

References 2 publications

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“…Since the surface of our finger is a (multicurved) twodimensional manifold (embedded in three dimensions), we parameterize it using two dimensionless variables (A, B). We use the surface parameterization introduced by Roşca [52] for spheres, which we extend to cover the cylindrical component of our finger (see Appendix). The resulting parameterization, illustrated in Fig.…”

Section: A Finger Geometry and Surface Parameterizationmentioning

confidence: 99%

A Sensorized Multicurved Robot Finger With Data-Driven Touch Sensing via Overlapping Light Signals

Piacenza

Behrman

Schifferer

et al. 2020

IEEE/ASME Trans. Mechatron.

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Despite significant advances in touch and force transduction, tactile sensing is still far from ubiquitous in robotic manipulation. Existing methods for building touch sensors have proven difficult to integrate into robot fingers due to multiple challenges, including difficulty in covering multicurved surfaces, high wire count, or packaging constrains preventing their use in dexterous hands. In this paper, we present a multicurved robotic finger with accurate touch localization and normal force detection over complex, three-dimensional surfaces. The key to our approach is the novel use of overlapping signals from light emitters and receivers embedded in a transparent waveguide layer that covers the functional areas of the finger. By measuring light transport between every emitter and receiver, we show that we can obtain a very rich signal set that changes in response to deformation of the finger due to touch. We then show that purely data-driven deep learning methods are able to extract useful information from such data, such as contact location and applied normal force, without the need for analytical models. The final result is a fully integrated, sensorized robot finger, with a low wire count and using easily accessible manufacturing methods, designed for easy integration into dexterous manipulators. P. Piacenza and M. Ciocarlie are with the

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Section: A Finger Geometry and Surface Parameterizationmentioning

confidence: 99%

A Sensorized Multicurved Robot Finger With Data-Driven Touch Sensing via Overlapping Light Signals

Piacenza

Behrman

Schifferer

et al. 2020

IEEE/ASME Trans. Mechatron.

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“…To find these values, we start by constructing a set of directions representatively covering real space. The regular spherical grid on a unit sphere described by Roşca (2010) is currently used to generate unit vectors u n from the origin to these grid nodes (Appendix A). The default grid step corresponds to 5 in the equatorial plane, which generates 361 vectors.…”

Section: Effective Resolution Along the Coordinate Axesmentioning

confidence: 99%

“…To calculate a grid on a sphere, the program uses the algorithm developed by Roşca (2010). To build a regular grid on a unit sphere, we define the grid number M; by default, M = 9.…”

Section: Appendix a Regular Grid On The Unit Spherementioning

confidence: 99%

EFRESOL: effective resolution of a diffraction data set

Urzhumtseva

Urzhumtsev

2015

J Appl Cryst

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The resolution of a diffraction data set conveys the details that one expects to distinguish in the Fourier maps calculated with these data. For example, individual atoms in a macromolecular chain cannot be resolved in the maps calculated with 2 Å resolution data sets, while they can be resolved in accurate maps calculated with 1 Å resolution data. However, if a data set is incomplete its high-resolution cutoff becomes less straightforward to interpret. For instance, a Fourier map calculated using a 1 Å resolution data set with many high-resolution reflections missing may rather resemble a map corresponding to 2 Å resolution data. The authors have proposed a method that redefines the traditional notion of data resolution, making it more formal and general. This manuscript presents the corresponding tool, the programEFRESOL. For a data set of an arbitrary completeness, the program calculates its mean, highest and lowest effective resolutions. These values are established through the minimum distance between two point scatterers when their images are still resolved as separate peaks in the Fourier maps calculated with the given data set. Additionally, the program calculates the optical resolution, which is defined as the minimum distance for typical atoms of the structure when they are resolved in a hypothetical synthesis obtained with the given amplitudes and the exact phases if they are known. Both effective and optical resolutions show the `resolving power' of the diffraction data set.

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“…The second step is to interpolate the intensities over the hemisphere onto the pixel locations on the collecting detector. We make use of an equal-area projection of the hemisphere onto a square or hexagonal grid [12] to permit standard bilinear interpolation of the intensities. The third step is to model additional instrument effects such as detector quantum efficiency, Poisson noise, coupling optics, and the point spread function and binning mode of the CCD.…”

Section: Construction Of Diffraction Pattern Dictionarymentioning

confidence: 99%

EBSD image segmentation using a physics-based forward model

Park

Wei

Graef

et al. 2013

2013 IEEE International Conference on Image Processing

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We propose a segmentation and anomaly detection method for electron backscatter diffraction (EBSD) images. In contrast to conventional methods that require Euler angles to be extracted from diffraction patterns, the proposed method operates on the patterns directly. We use a forward model implemented as a dictionary of diffraction patterns generated by a detailed physics-based simulation of EBSD. The combination of full diffraction patterns and a dictionary allows anomalies to be detected at the same time as grains are segmented, and also increases robustness to noise and instrument blur. The proposed method is demonstrated on a sample of the Ni-base alloy IN100.

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New uniform grids on the sphere

Cited by 41 publications

References 2 publications

A Sensorized Multicurved Robot Finger With Data-Driven Touch Sensing via Overlapping Light Signals

A Sensorized Multicurved Robot Finger With Data-Driven Touch Sensing via Overlapping Light Signals

EFRESOL: effective resolution of a diffraction data set

EBSD image segmentation using a physics-based forward model

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