The Experts below are selected from a list of 21357 Experts worldwide ranked by ideXlab platform
Alin Albuschaffer - One of the best experts on this subject based on the ideXlab platform.
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workSpace fixation for free floating Space robot operations
International Conference on Robotics and Automation, 2018Co-Authors: Alessandro Massimo Giordano, Davide Calzolari, Alin AlbuschafferAbstract:When a Space robot accidentally or voluntarily comes in contact with a target object, a workSpace shift happens due to exchange of momentum between the objects. The problem of workSpace adjustment is addressed herein. A novel controller is derived to simultaneously adjust the workSpace and control the end-effector pose. The controller is based on a center-of-mass (CoM) regulation which fixes the workSpace in the Inertial Space while leaving the base free to move, resulting in fuel efficiency. The control is validated on hardware using a robotic simulator composed of a seven degree-of-freedom (DOF) arm mounted on a 6DOF moving base.
G Blewitt - One of the best experts on this subject based on the ideXlab platform.
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self consistency in reference frames geocenter definition and surface loading of the solid earth
Journal of Geophysical Research, 2003Co-Authors: G BlewittAbstract:[1] Crustal motion can be described as a vector displacement field, which depends on both the physical deformation and the reference frame. Self-consistent descriptions of surface kinematics must account for the dynamic relationship between the Earth's surface and the frame origin at some defined center of the Earth, which is governed by the Earth's response to the degree-one spherical harmonic component of surface loads. Terrestrial reference frames are defined here as “isomorphic” if the computed surface displacements functionally accord with load Love number theory. Isomorphic frames are shown to move relative to each other along the direction of the load's center of mass. The following frames are isomorphic: center of mass of the solid Earth, center of mass of the entire Earth system, no-net translation of the surface, no-net horizontal translation of the surface, and no-net vertical translation of the surface. The theory predicts different degree-one load Love numbers and geocenter motion for specific isomorphic frames. Under a change in center of mass of surface load in any isomorphic frame, the total surface displacement field consists not only of a geocenter translation in Inertial Space, but must also be accompanied by surface deformation. Therefore estimation of geocenter displacement should account for this deformation. Even very long baseline interferometry (VLBI) is sensitive to geocenter displacement, as the accompanying deformation changes baseline lengths. The choice of specific isomorphic frame can facilitate scientific interpretation; the theory presented here clarifies how coordinate displacements and horizontal versus vertical motion are critically tied to this choice.
David B Wilson - One of the best experts on this subject based on the ideXlab platform.
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the martini synch
2007Co-Authors: Darko Kirovski, Mike Sinclair, David B WilsonAbstract:Device pairing is a significant problem for a large class of increasingly popular resource-constrained wireless protocols such as BlueTooth. The objective of pairing is to establish a secure wireless communication channel between two specific devices without a public-key infrastructure, a secure near-field communication channel, or electrical contact. We use a surprising user-device interaction as a solution to this problem. By adding an accelerometer, a device can sense its motion in a Cartesian Space relative to the Inertial Space. The idea is to have two devices in a fixed, relative position to each other. Then, the joint object is moved randomly in 3D for several seconds. The unique motion generates approximately the same distinct signal at the accelerometers. The difference between the signals in the two Inertially conjoined sensors should be relatively small under normal motion induced manually. The objective is to derive a deterministic key at both sides with maximized entropy that will be used as a private key for symmetric encryption. Currently, our prototype produces between 10–15 bits of entropy per second of usual manual motion using off-the-shelf components.
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the martini synch joint fuzzy hashing via error correction
Security of ad hoc and Sensor Networks, 2007Co-Authors: Darko Kirovski, Michael J Sinclair, David B WilsonAbstract:Device pairing is a significant problem for a large class of increasingly popular resource-constrained wireless protocols such as Bluetooth. The objective of pairing is to establish a secure wireless communication channel between two specific devices without a public-key infrastructure, a secure near-field communication channel, or electrical contact. We use a surprising user-device interaction as a solution to this problem. By adding an accelerometer, a device can sense its motion in a Cartesian Space relative to the Inertial Space. The idea is to have two devices in a fixed, relative position to each other. Then, the joint object is moved randomly in 3D for several seconds. The unique motion generates approximately the same distinct signal at the accelerometers. The difference between the signals in the two Inertially conjoined sensors should be relatively small under normal motion induced manually. The objective is to derive a deterministic key at both sides with maximized entropy that will be used as a private key for symmetric encryption. Currently, our prototype produces between 10-15 bits of entropy per second of usual manual motion using off-the-shelf components.
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the martini synch device pairing via joint quantization
International Symposium on Information Theory, 2007Co-Authors: Darko Kirovski, Michael J Sinclair, David B WilsonAbstract:Device pairing is a significant problem for a large class of increasingly popular resource-constrained wireless protocols such as Bluetooth. The objective of pairing is to establish a secure wireless communication channel between two specific devices without a public-key infrastructure, a secure near-field communication channel, or electrical contact. In this paper, we use a surprising user-device interaction as a solution to this problem. By adding a 3-axis accelerometer, a device can sense its motion in local Cartesian Space relative to the Inertial Space. The idea is to have two devices in a fixed, relative position to each other. The joint object is then moved randomly in 3D for several seconds. The unique and difficult to reproduce motion generates approximately the same distinct signal at each accelerometer. The difference between the signals in the two Inertially conjoined sensors should be relatively small under normal motion induced manually except for a fixed attitude offset. The objective is to derive a deterministic key at both sides with maximized entropy that will be used as a private key for symmetric encryption. Currently, our prototype produces 9-20 bits of entropy per second of usual manual motion using off-the-shelf components.
Alessandro Massimo Giordano - One of the best experts on this subject based on the ideXlab platform.
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workSpace fixation for free floating Space robot operations
International Conference on Robotics and Automation, 2018Co-Authors: Alessandro Massimo Giordano, Davide Calzolari, Alin AlbuschafferAbstract:When a Space robot accidentally or voluntarily comes in contact with a target object, a workSpace shift happens due to exchange of momentum between the objects. The problem of workSpace adjustment is addressed herein. A novel controller is derived to simultaneously adjust the workSpace and control the end-effector pose. The controller is based on a center-of-mass (CoM) regulation which fixes the workSpace in the Inertial Space while leaving the base free to move, resulting in fuel efficiency. The control is validated on hardware using a robotic simulator composed of a seven degree-of-freedom (DOF) arm mounted on a 6DOF moving base.
D F Roscoe - One of the best experts on this subject based on the ideXlab platform.
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a proposed theoretical basis for a mond cosmology i the Inertial frame
General Relativity and Gravitation, 2002Co-Authors: D F RoscoeAbstract:This paper is essentially a speculation on the realization of Mach's Principle, and we came to the details of the present analysis via the formulation of two questions: (a) Can a globally Inertial Space & time be associated with a non-trivial global matter distribution? (b) If so, what are the general properties of such a global distribution?
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a proposed theoretical basis for a mond cosmology i the Inertial frame
arXiv: Astrophysics, 2001Co-Authors: D F RoscoeAbstract:This first of two papers is a speculation on the nature of Mach's Principle, derived from the formulation of two questions: (A) Can a globally Inertial Space and time be associated with a non-trivial global matter distribution? (B) If so, what are the general properties of such a global distribution? The answers are yes subject to the condition that mass is distributed fractally with D=2. Such a prediction is supported, for example, in Joyce, Montuori, Labini astro-ph/9901290. The second paper then shows how gravitational phenomena arise as consequences of perturbations of this equilibrium D=2 distribution, and applies this theory to spiral galaxy dynamics. Specifically, the second paper derives a gravitational model for an idealized spiral, defined to have perfect cylindrical symmetry. One of the main results of this analysis is that, *in the disc*, V_rot = A/R^alpha where (A, alpha) are constants which vary between spirals. See astro-ph/0107305, which concludes that a power-law model is powerfully confirmed for ORCs as a statistical generality over large samples, and astro-ph/0107300 for new phenomonology discovered via this analysis. Thus, unlike MOND, we have only been concerned with model predictions made for idealized matter distributions, and tested over very large numbers of ORCs. But, like those of MOND, the predictions are very powerfully supported on the data. For this reason, we hypothesize that perspectives of MOND are buried within our own formalism. This remains a topic for future work.