| Analysis and Experimentation of Control Strategies for Underactuated Spacecraft |
Sep-2009 |
180 pages |
| Authors:
Jason S Hall; MAN MACHINE SYSTEMS INC ARLINGTON VA
|
 | A laboratory spacecraft simulator testbed is first introduced to examine the problem of multiple spacecraft interacting in close proximity. This testbed enables validation of guidance, navigation and control (GNC) algorithms by combining 6-Degrees of Freedom (DoF) computer simulation with 3-DoF Hardware-In-the-Loop (HIL) experimentation. The presented 3-DoF spacecraft simulator employs a novel control actuator configuration consisting of a Miniature Single Gimbaled Control Moment Gyroscope (MSGCMG) and dual on/off cold-gas in-plane vectorable ... |
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| Animating a Human Body Mesh with Maya for Doppler Signature Computer Modeling |
Jun-2009 |
20 pages |
| Authors:
Getachew Kirose; ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE
|
| The Maya software package has been used by researchers at the U.S. Army Research Laboratory (ARL) to create human body motion animation for the purpose of simulating the radar signature of a moving human target. This report describes how to use Maya's powerful graphics user interface (GUI) in order to create realistic frame-by-frame animation of a human mesh in walking motion. The examples presented here also include a human equipped ... |
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| Super Maneuverable, Flapping Wing Micro-Air-Vehicles |
16-Mar-2009 |
28 pages |
| Authors:
B Balachandran; E Balaras; Marcos Vanella; Timothy Fitzgerald; Sergio Preidikman; MARYLAND UNIV COLLEGE PARK DEPT OF MECHANICAL ENGINEERING
|
| Interest in the development of super-maneuverable, micro-air-vehicles has led to the re-examination of basic flight modes, particularly, those that are inspired by biological observations. The majority of experimental and numerical studies related to flapping flight have explored the relationships between the thrust coefficient (and propulsive efficiency) and wing geometry and kinematics. Relatively speaking, the wing flexibility and the interplay between kinematics and flexibility have received less attention, and currently, it ... |
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| Bio-Mimetic Millimeter-Scale Flapping Wings for Micro Air Vehicles |
Mar-2009 |
22 pages |
| Authors:
Eric Wetzel; Ronald G Polcawich; Christopher Kroninger; Jeffrey Pulskamp; Jessica Bronson; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| In this report, we present designs of Micro-Electro-Mechanical System (MEMS) fabricated millimeter-scale flapping wings with some characterization of their structural properties and flapping performance. Wings of varied bio-mimetic design, including membrane and ribs-like structures, are flapped at resonance from lead zirconate titanate (PZT) bending actuators at their base. Laser Doppler vibrometer (LDV) measurements and finite element (FE) analysis predictions of the flapping frequencies and mode shapes and the flapping amplitude ... |
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| Computational Fluid Dynamics Studies of a Flapping Wing Nano Air Vehicle (NAV) |
31-Dec-2008 |
51 pages |
| Authors:
Ravi Ramamurti; Jason Geder; William C Sandberg; NAVAL RESEARCH LAB WASHINGTON DC CENTER FOR REACTIVE FLOW AND DYNAMICAL SYSTEMS
|
| The goal of this project is to develop a Nano Air Vehicle (NAV) with a wing span of 7.5 cm. The computational fluid dynamics study is focused on the aerodynamic efficiency of the wings. The primary focus of the computational study is on the aerodynamic performance of the wings in order to obtain a near optimal kinematics of the wing while the NAV is in a hover mode. The secondary ... |
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| Coordinated Control of a Planar Dual-Crane Non-Fully Restrained System |
Dec-2008 |
415 pages |
| Authors:
Frank A Leban; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| In this dissertation a control scheme that would provide motion compensation for a ship-based two-crane system suspending a single payload was developed. Historical experience during the conflict in Vietnam, along with the introduction of standard containerized packaging have steered military sustainment logistics towards a reliance on commercially developed cranes for discharge of containers - even for instream lightering operations. With the inclusion of Seabasing as one of the Navy's pillars, ... |
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| A Framework for Integrated Tracking and Discrimination |
Dec-2008 |
5 pages |
| Authors:
Andrew David; David Fiske; DECISIVE ANALYTICS CORP ARLINGTON VA
|
| The Decisive Analytics Corporation (DAC) team describes a framework to fully integrate the tracking and discrimination processes in the Ballistic Missile Defense System (BMDS).The contributions developed under this work center on fully integrating the tracking and discrimination processes in the Ballistic Missile Defense System (BMDS). The current architecture of the BMDS artificially separates the tracking and discrimination algorithms. Each model exists independently with no ability to influence the operation of ... |
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| Biomimetic Oscillating Foil Propulsion to Enhance Underwater Vehicle Agility and Maneuverability |
Jun-2008 |
|
| Authors:
Stephen C Licht; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
 | Inspired by the swimming abilities of marine animals, this theses presents Finnegan the RoboTurtle, an autonomous underwater vehicle (AUV) powered entirely by four flapping foils. Biomimetic actuation is shown to produce dramatic improvements in AUV maneuvering at cruising speeds, while simultaneously allowing for agility at low speeds. Using control algorithms linear in the modified Rodrigues parameters to support large angle maneuvers, the vehicle is successfully controlled in banded and twisting ... |
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| Enormous Disc of Cool Gas Surrounding the Nearby Powerful Radio Galaxy NGC 612 (PKS 0131-36) |
22-May-2008 |
15 pages |
| Authors:
R Ojha; B H Emonts; R Morganti; T A Oosterloo; J Holt; C N Tadhunter; van Hulst; J M der; E M Sadler; COLUMBIA UNIV NEW YORK DEPT OF ASTRONOMY
|
| We present the detection of an enormous disc of cool neutral hydrogen (HI) gas surrounding the SO galaxy NGC 612, which hosts one of the nearest powerful radio sources (PKS 0131-36). Using the Australia Telescope Compact Array, we detect M(HI) = 1.8 x 10(9) M(.) of HI emission-line gas that is distributed in a 140 kpc wide disc-like structure along the optical disc and dust-lane of NGC 612. The bulk ... |
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| Computational Design of Upperstage Chamber Aerospike and Cooling Jacket for Dual-Expander Rocket Engine |
MAR 2008 |
135 pages |
| Authors:
David F. Martin; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
|
| To increase the performance of the current US satellite launch capability, new rocket designs must be undertaken. One concept that has been around since the 50s but yet to be utilized on a launch platform is the aerospike, or plug nozzle. The aerospike nozzle concept demonstrates globally better performance compared to a conventional bell nozzle, since the expansion of the jet is not bounded by a wall and therefore can ... |
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| Diagnostic-Photographic Determination of Drag/Lift/Torque Coefficients of High Speed Rigid Body in Water Column |
01-Jan-2008 |
51 pages |
| Authors:
Chenwu Fan; Peter C Chu; Paul R Gefken; NAVAL POSTGRADUATE SCHOOL MONTEREY CA NAVAL OCEAN ANALYSIS AND PREDICTION LAB
|
| Prediction of rigid body falling through water column with a high speed (such as Mk-84 bomb) needs formulas for drag/lift and torque coefficients, which depend on various physical processes such as supercavitation and bubbles. A diagnostic-photographic method is developed in this study to determine the drag/lift and torque coefficients for a fast moving rigid-body in water column. The diagnostic part is to derive the relationships (called diagnostic relationships) between (drag, ... |
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| Two Stellar Components in the Halo of the Milky Way |
13 DEC 2007 |
8 pages |
| Authors:
Daniela Carollo; Timothy C. Beers; Young-Sun Lee; Masashi Chiba; John E. Norris; Ronald Wilhelm; Thirupathi Sivarani; Brian Marsteller; Jeffrey A. Munn; Coryn A. Bailer-Jones; NAVAL OBSERVATORY FLAGSTAFF AZ
|
| The halo of the Milky Way provides unique elemental abundance and kinematic information on the first objects to form in the Universe, and this information can be used to tightly constrain models of galaxy formation and evolution. Although the halo was once considered a single component, evidence for its dichotomy has slowly emerged in recent years from inspection of small samples of halo objects. Here we show that the halo ... |
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| Exploring the Local Milky Way: M Dwarfs as Tracers of Galactic Populations |
DEC 2007 |
13 pages |
| Authors:
John J. Bochanski; Jeffrey A. Munn; Suzanne L. Hawley; Andrew A. West; Kevin R. Covey; Donald P. Schneider; WASHINGTON UNIV SEATTLE
|
| We have assembled a spectroscopic sample of low-mass dwarfs observed as part of the Sloan Digital Sky Survey along one Galactic sight line, designed to investigate the observable properties of the thin and thick disks. This sample of ~7400 K and M stars also has measured ugriz photometry, proper motions, and radial velocities. We compute UVW space-motion distributions, and investigate their structure with respect to vertical distance from the Galactic ... |
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| Development of a Vehicle Model/Simulation Evaluation Tool |
08 NOV 2007 |
12 pages |
| Authors:
J. G. Howe; Jeffrey P. Chrstos; Richard Romano; James O'Kins; TACOM RESEARCH DEVELOPMENT AND ENGINEERING CENTER WARREN MI
|
| As part of the evaluation of vehicle simulation models, a vehicle dynamics engineer typically desires to compare simulation results to test data from actual vehicles and/or results from known, or higher fidelity simulations. Depending on the type of model, several types of tests and/or maneuvers may need to be compared. For military vehicles, there is the additional requirement to run specific types of maneuvers for vehicle model evaluations to ensure ... |
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| Recent Progress Towards Developing an Insect-Inspired Flapping-Wing Micro Air Vehicle |
01 NOV 2007 |
|
| Authors:
K. Knowles; S. A. Ansari; P. C. Wilkins; R. W. Zbikowski; CRANFIELD UNIV (UNITED KINGDOM) DEPT OF AEROSPACE POWER AND SENSORS
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| This paper presents an overview of the on-going research activities at Shrivenham, aimed at the design of an autonomous flapping-wing micro air vehicle. After introducing the problem of insect wing kinematics and aerodynamics, we describe our quasi-three-dimensional aerodynamic model for flapping wings. This is followed by a brief discussion of some aerodynamic issues relating to the lift-generating leading-edge vortex. New results are then presented on modelling of wing aeroelastic deflections. ... |
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| Synthesis of Nonlinear Guidance Laws for Missiles with Uncertain Dynamics |
NOV 2007 |
|
| Authors:
C. A. Rabbath; N. Lechevin; DEFENCE RESEARCH AND DEVELOPMENT CANADA VALCARTIER (QUEBEC)
|
| This technical memorandum describes a nonlinear guidance law for a single-missile single-target engagement. The guidance relies on the concepts of Lyapunov stability and backstepping, which are constructive methods in nonlinear control theory. The design of the guidance law allows taking into account the nonlinear relative kinematics between the missile and the target, and ensuring ultimate boundedness of the missile-target system trajectories provided the estimation error of the target acceleration is ... |
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| Math-Based Simulation Tools and Methods |
10 OCT 2007 |
17 pages |
| Authors:
Sudhakar Arepally; ARMY RESEARCH DEVELOPMENT AND ENGINEERING COMMAND WARREN MI
|
| These briefing charts review numerous mathematical methods for simulating crashworthiness and occupant protection in motor vehicles. The following methods are reviewed: matrix operations, ordinary and partial differential system of equations, Lagrangian operations, Fourier transforms, Taylor Series, Finite Difference Methods, implicit and explicit finite element methods, and statistical methods (probabilistic and regression analysis). The slides are labeled as follows: HMMWV 30-mph Rollover Test, Soldier Gear Effects, Occupant Performance in Blast Effects, ... |
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| Astrometry With Digital Sky Surveys: From SDSS to LSST |
Oct-2007 |
8 pages |
| Authors:
Z Ivezic; P Pinto; A J Tyson; G R Knapp; J E Gunn; J A Munn; B Sesar; M Juric; N Bond; D G Monet; R H Lupton; K Cook; WASHINGTON UNIV SEATTLE DEPT OF ASTRONOMY
|
| Major advances in our understanding of the Universe have historically come from dramatic improvements in our ability to accurately measure astronomical quantities. The astrometric observations obtained by modern digital sky surveys are enabling unprecedentedly massive and robust studies of the kinematics of the Milky Way. For example, the astrometric data from the Sloan Digital Sky Survey (SDSS), together with half a century old astrometry from the Palomar Observatory Sky Survey ... |
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| Multi-Camera, High-Speed Imaging System for Kinematics Data Collection |
21 SEP 2007 |
14 pages |
| Authors:
Jason Geder; William C. Sandberg; Ravi Ramamurti; NAVAL RESEARCH LAB WASHINGTON DC
|
| A two-camera system was devised and created to determine the kinematics of flapping fin and flapping wing vehicles. Each camera is set up to capture triggered, high-speed (up to 10,000 frames per second) images of the appendage in a test environment. Using direct linear transforms, each camera is calibrated to convert image coordinates to an alternate coordinate system. Points of interest on the appendage are selected from each camera image ... |
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| Water Maser Kinematics in the Jet of OH 12.8-0.9 |
10 AUG 2007 |
11 pages |
| Authors:
David A. Boboltz; Kevin B. Marvel; NAVAL OBSERVATORY WASHINGTON DC
|
| We present Very Long Baseline Array observations of the kinematics of the water masers associated with OH 12.8-0.9, the fourth member of the so-called water-fountain class of sources. We find that the masers occupy two distinct regions at the ends of a bipolar jetlike structure oriented north-south, with the blue-shifted masers located to the north and the red-shifted masers to the south. The masers are distributed along arc-like structures 12-20 ... |
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| Synchronous Deployed Solar Sail Subsystem Design Concept |
APR 2007 |
14 pages |
| Authors:
Jeremy A. Banik; Thomas W. Murphey; CSA ENGINEERING INC ALBUQUERQUE NM
|
| A solar sail concept has been developed from a common spiral fold pattern in order to enable a simultaneous mast and sail deployment. This novel concept utilizes the stored strain energy in a series of elastic spar members to enforce proper folding kinematics rather than relying on bulky mechanical joints. The critical inner and outer spar networks are secured to four elastically extendible masts anchored to a central drum. Deployment ... |
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| Analytical Solutions for Open Channel Temperature Response to Unsteady Thermal Discharge and Boundary Heating |
Jan-2007 |
40 pages |
| Authors:
H S Tang; T R Keen; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| Analytical solutions are derived for a one-dimensional model of the bulk temperature response of open-channel flow with unsteady and nonuniform heating at an upstream boundary, the water surface, and the riverbed. The model describes the temperature variation as kinematic waves, and the solutions are explicit formulas that are comprised of transient terms, which play dominant roles at the upstream end, and equilibrium terms, which determine the temperature far downstream. It ... |
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| Cross Domain Analogies for Learning Domain Theories |
2007 |
7 pages |
| Authors:
Matthew Klenk; Ken Forbus; NORTHWESTERN UNIV EVANSTON IL QUALITATIVE REASONING GROUP
|
| Analogical reasoning has long been seen as a powerful way of extending the reach of ones knowledge. One product of analogical reasoning is analogical learning in which the result of the comparison increases our understanding of some domain. This work describes a method for learning new domain theories by analogy. We use analogies between pairs of problems and worked solutions to create a domain mapping between a familiar and a ... |
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| Learning Domain Theories via Analogical Transfer |
2007 |
7 pages |
| Authors:
Matthew Klenk; Kenneth D. Forbus; NORTHWESTERN UNIV EVANSTON IL
|
| Learning domain theories is an important challenge for qualitative reasoning. We describe a method for learning new domain theories by analogy. We use analogies between pairs of problems and worked solutions to create a mapping between the familiar and the new domains, and use this mapping to conjecture general knowledge about the new domain. After some knowledge has been learned about the new domain, another analogy is made between the ... |
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| A Multiscale Modeling Method for Deformations on Atomic Lattice Defects and Application to Plasticity |
NOV 2006 |
27 pages |
| Authors:
Peter W. Chung; John D. Clayton; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Computing the displacements of atoms undergoing deformation in a perfect lattice requires the use of the so-called Cauchy-Born approximation. Near defects such as at vacancies or dislocations, this approximation does not hold and a computationally costly energy minimization over a large number of atoms is unavoidable. Presented is a self-consistent multiscale methodology enabling an approximation to the displacements near defects without requiring full energy minimization over successive load increments. It ... |
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| Adaptive Control Responses to Behavioral Perturbation Based Upon the Insect |
NOV 2006 |
29 pages |
| Authors:
R. E. Ritzmann; R. D. Quinn; M. A. Willis; Chris E. Perry; CASE WESTERN RESERVE UNIV CLEVELAND OH
|
| The Munitions Directorate at Eglin AFB FL supported research at Case Western Reserve University (CWRU) in Cleveland OH describing transitional behaviors in insect walking and in flight. Quantitative descriptions of the complex decisions that a cockroach makes in deciding to climb over or tunnel under a barrier allowed the examinations of discrete brain lesions in order to pin point where and how these decisions are made. Documentation of turning movements ... |
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| Trajectory Control for Very Flexible Aircraft |
30 OCT 2006 |
47 pages |
| Authors:
Christopher M. Shearer; Cesnik E. Carlos; MICHIGAN UNIV ANN ARBOR
|
| This paper focuses on trajectory control of the 6-DOF body fixed reference frame located on a very flexible aircraft. The 6-DOF equations of motion of a reference point on the aircraft are coupled with the aeroelastic equations that govern the geometrically nonlinear structural response of the vehicle. A low-order strain-based nonlinear structural analysis coupled with unsteady finitestate potential flow aerodynamics form the basis for the aeroelastic model. The nonlinear beam ... |
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| Emulating the Fast-Start Swimming Performance of the Chain Pickerel (Esox niger) Using a Mechanical Fish Design |
01 SEP 2006 |
|
| Authors:
Matthew N. Watts; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
| Mean maximum start-up accelerations and velocities achieved by the fast-start specialist, northern pike, are reported at 120 m/s sq and 4 m/s, respectively (Harper and Blake, 1990). In this thesis, a simple mechanical system was created to closely mimic the startle response that produces these extreme acceleration events. The system consisted of a thin metal beam covered by a urethane rubber fish body. The mechanical fish was held in curvature ... |
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| Development and Testing of a High-Speed Real-Time Kinematic Precise DGPS Positioning System Between Two Aircraft |
SEP 2006 |
483 pages |
| Authors:
Christopher J. Spinelli; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This research involves the design, implementation, and testing of a high-speed, real-time kinematic, precise differential GPS positioning system for use in airborne applications such as automated aerial-refueling and close formation flying. Although many of the current ambiguity resolution techniques use the residuals from the least squares position estimation to determine the true ambiguity set, this thesis presents a novel approach to the ambiguity resolution problem, called the minimum indicator. Instead ... |
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| MHD Flow Control |
SEP 2006 |
236 pages |
| Authors:
Valentin A. Bityurin; RUSSIAN ACADEMY OF SCIENCES MOSCOW INST OF HIGH TEMPERATURES
|
| This report results from a contract tasking Institute of High Temperatures RAS as follows: Task I: Renewed scientific interest has arisen throughout the world as to the potential application of Magneto Hydrodynamics (MHD) processes for advancement of flight. Among the areas of interest is the utilization of MHD as a means for enhancing the speed and range of scramjets through a concept known as MHD energy bypass. Currently. scramjet operation ... |
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| Near Wall Velocity and Vorticity Measurements, In A Very High R(theta) Turbulent Boundary Layer |
15 JUN 2006 |
87 pages |
| Authors:
Scott C. Treat; John F. Foss; MICHIGAN STATE UNIV EAST LANSING DEPT OF MECHANICAL ENGINEERING
|
| Velocity and vorticity measurements have been obtained at two y+ values: 810 and 2,150, in the very high R(theta)(O 10(exp 6)) turbulent boundary layer at the SLTEST site, Dugway Proving Grounds, Utah. Detailed descriptions of the experimental procedures are reported in order to allow the processed results to be evaluated. The research focus is on the velocity-vorticity products that appear in the formal statement of the vertical gradient of the ... |
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| New Tracking Filter Algorithm Using Input Parameter Estimation |
JUN 2006 |
97 pages |
| Authors:
Corey M. Broussard; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| A new method for the design of tracking filters for maneuvering targets, based on kinematic models and input signals estimation, is developed. The input signal's level, u is considered a continuous variable and consequently the input estimation problem is posed as a purely parameter estimation problem. Moreover, the application of the new tracking filter algorithm is not contingent on distinguishing maneuvering and non-maneuvering targets, and does not require the detection ... |
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| Biomimetic Design of an Under-Actuated Leg Exoskeleton for Load-Carrying Augmentation |
01-Feb-2006 |
97 pages |
| Authors:
Conor J Walsh; MASSACHUSETTS INST OF TECH CAMBRIDGE MEDIA LAB
|
| Metabolic studies have shown that there is a metabolic cost associated with carrying a load. Previous work on exoskeleton design has not considered the passive dynamics of walking and has focused on fully actuated systems that are inefficient and heavy. In this thesis, an underactuated exoskeleton is presented that runs parallel to the human leg. The exoskeleton component design is based on the kinematics and kinetics of human walking. The ... |
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| Modeling Dislocations and Disclinations with Finite Micropolar Elastoplasticity |
FEB 2006 |
54 pages |
| Authors:
John D. Clayton; David L. McDowell; Douglas J. Bammann; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Aspects of a constitutive model for characterizing crystalline metals containing a distribution of dislocation and disclination defects are presented. Kinematics, balance laws, and general kinetic relations are developed from the perspective of multiscale volume averaging upon examination of a deforming crystalline element containing a distribution of displacement discontinuities in the form of translational and rotational lattice defects, i.e., dislocations and disclinations. The macroscopic kinematic description is characterized by a three-term ... |
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| Trauma Pod/Operating Room of the Future |
FEB 2006 |
113 pages |
| Authors:
Delbert Tesar; Chetan Kapoor; Chalongarh Pholsiri; Edwin Jung; Greg Giem; Jonathan Knoll; TEXAS UNIV AT AUSTIN
|
| The University of Texas at Austin (UTA) has played a central role in the trauma pod project and has been responsible for the following: (1) systems engineering and design from a robotics perspective, (2) a high-fidelity 3D simulator, (3) motion planning software for the scrub nurse systems, and (4) the supervisory control system (SCS). In systems engineering and design, UTA specified a hierarchical control architecture for the trauma pod and ... |
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| A Multiscale Gradient Theory for Single Crystalline Elastoviscoplasticity |
FEB 2006 |
38 pages |
| Authors:
John D. Clayton; David L. McDowell; Douglas J. Bammann; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Explicit volume averaging procedures are used to motivate a gradient-type description of single crystalline elastoviscoplasticity. Upon regarding local elastic and plastic deformation gradients within the crystal as continuously differentiable fields, we arrive at a three-term multiplicative decomposition for the volume-averaged deformation gradient, consisting of a recoverable elastic term associated with the average applied stress and average lattice rotation, an inelastic term associated with the average plastic velocity gradient, and a ... |
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| Trauma Pod/Operating Room of the Future |
FEB 2006 |
113 pages |
| Authors:
Delbert Tesar; Chetan Kapoor; Chalongarh Pholsiri; Edwin Jung; Greg Giem; Jonathan Knoll; TEXAS UNIV AT AUSTIN
|
| The University of Texas (UTA) has played a central role in the trauma pod project and has been responsible for: 1) systems engineering and design from a robotics perspective, 2) high fidelity 3D simulator, 3) motion planning software for the scrub nurse systems, and 4) the supervisory control system (SCS). In systems engineering and design, UTA specified a hierarchical control architecture for the trauma pod and also recommended a communications ... |
|
| Ship-Track Models Based on Poisson-Distributed Port-Departure Times |
20 JAN 2006 |
39 pages |
| Authors:
Richard Heitmeyer; NAVAL RESEARCH LAB WASHINGTON DC ACOUSTIC SIGNAL PROCESSING BRANCH
|
| This report presents two models that describe the tracks of ships during an arbitrary time interval. Both models consist of a track function that describes the tracks of the individual ships and a probability law on the total number of ships en route during the interval, the initial positions of those ships, and their nominal speeds. The probability law assumes that the ship departure times are Poisson-distributed with a time-varying ... |
|
| The White Dwarf Luminosity Function from Sloan Digital Sky Survey Imaging Data |
JAN 2006 |
12 pages |
| Authors:
Hugh C. Harris; Jeffrey A. Munn; Mukremin Kilic; James Liebert; S. J. Kleinman; T. S. Metcalfe; Masataka Fukugita; G. R. Knapp; J. A. Smith; Donald P. Schneider; NAVAL OBSERVATORY FLAGSTAFF AZ
|
| A sample of white dwarfs is selected from the Sloan Digital Sky Survey (SDSS) Data Release 3 using their reduced proper motions, based on improved proper motions from combined SDSS and USNO-B data. Numerous SDSS and follow-up spectra (Kilic and coworkers) are used to quantify completeness and contamination of the sample; kinematics models are used to understand and correct for velocity-dependent selection biases. A luminosity function is constructed covering the ... |
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| Signature-Aided Tracking Using HRR Profiles |
2006 |
12 pages |
| Authors:
Kevin J. Sullivan; Matthew B. Ressler; Robert L. Williams; TOYON RESEARCH CORP GOLETA CA
|
| This paper describes a methodology for using high-range-resolution ground-moving-target-indicator (HRRGMTI) profiles to aid the association process in an automated tracker. The tracker uses a Kalman filter to estimate the state of targets. These state estimates are used in addition to HRRGMTI measurements to perform data association. The HRRGMTI profiles used to develop and test the system are simulated using the MSTAR dataset of synthetic aperture radar (SAR) imagery. The performance ... |
|
| Rapid Ambiguity Resolution Using Multipath Spatial Processing for High Accuracy Carrier Phase |
2006 |
9 pages |
| Authors:
Alison Brown; Kees Stolk; NAVSYS CORP COLORADO SPRINGS CO
|
| The largest error component on the carrier-phase observations is generally caused by carrier-phase multipath offsets. This generally results in a slow oscillating cyclic offset which must be averaged (either through satellite or vehicle motion) before reliable ambiguity resolution can be performed for kinematic positioning. NAVSYS has developed a digital spatial processing receiver that uses the spatial degrees of freedom within an antenna array to minimize multipath errors on the carrier-phase ... |
|
| Classical Observations of Visual Binary and Multiple Stars |
2006 |
10 pages |
| Authors:
Brian D. Mason; NAVAL OBSERVATORY WASHINGTON DC ASTROMETRY DEPT
|
| Changes in the double star database are highlighted, describing various methods of observation (both historically and those of the past few years) and their effectiveness in different regimes of separation space. The various niches for wide- and narrow-field work as they apply to double and multiple stars are examined and the different types of information which each can provide are described. Despite the significant growth of the double star database, ... |
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| Neural Network Grasping Controller for Continuum Robots |
2006 |
12 pages |
| Authors:
D. Braganza; D. M. Dawson; I. D. Walker; N. Nath; CLEMSON UNIV SC DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| Continuum or hyper-redundant robots are robots which exhibit behavior similar to biological trunks, tentacles and snakes. Unlike traditional robots, continuum robot manipulators do not have rigid joints, hence the manipulators are compliant, extremely dexterous, and capable of dynamic, adaptive manipulation in unstructured environments; however, the development of high-performance control algorithms for these manipulators is a challenging problem. In this paper, we present an approach to whole arm grasping control for ... |
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| Velocity and Structure Estimation of a Moving Object Using a Moving Monocular Camera |
2006 |
10 pages |
| Authors:
V. K. Chitrakaran; D. M. Dawson; J. Chen; H. Kannan; CLEMSON UNIV SC DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| In this paper, we present the development of a vision-based estimator for simultaneous determination of velocity and structure of an object (i.e., the Euclidean position of its feature points) for the general case where both the object and the camera are moving relative to an inertial frame of reference. The velocity estimation itself requires no explicit kinematic model, while the adaptive structure estimator, synthesized utilizing Lyapunov design methods, is built ... |
|
| Modeling of Unilateral Contact Conditions in Aerospace Systems |
31 DEC 2005 |
174 pages |
| Authors:
Olivier A. Bauchau; Aldo A. Ferri; GEORGIA INST OF TECH ATLANTA SCHOOL OF AEROSPACE ENGINEERING
|
| Multibody dynamics analysis is a powerful tool for the comprehensive simulation of the dynamic response of various flexible aerospace systems that are important to the Air Force. Systems of arbitrary topology and complexity can be readily modeled; they include both aircraft and spacecraft. In present formulations, the joints connecting the various flexible bodies are not modeled per se. Rather, the effect of joints, i.e. the constraints they impose on the ... |
|
| Optimal Crash Pulse for Minimization of Peak Occupant Deceleration in Frontal Impact |
OCT 2005 |
11 pages |
| Authors:
Zhiqing Cheng; Joseph A. Pellettiere; GENERAL DYNAMICS ADVANCED INFORMATION ENGINEERING SERVICES INC DAYTON OH
|
| In automobile frontal impact, for given restraint characteristics and prescribed impact speed and crash deformation, what is the optimal vehicle crash pulse that produces the lowest peak occupant deceleration? In this paper, based on a lumped-parameter model of the occupant-vehicle system, the problem is treated as a best disturbance problem of the optimal protection from impact. The optimum kinematics of the occupant in frontal impact is found. For linear restraint ... |
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| Optimal Restraint Characteristics for Minimization of Peak Occupant Deceleration in Frontal Impact |
OCT 2005 |
11 pages |
| Authors:
Zhiqing Cheng; Joseph A. Pellettiere; GENERAL DYNAMICS ADVANCED INFORMATION SYSTEMS DAYTON OH
|
| In automobile frontal impact, given the vehicle motion and the interior free space for the occupant's excursion, what are the optimal characteristics of restraint systems for the minimization of the peak occupant deceleration? In this paper, the problem is treated as the optimal protection from impact based on a lumped-parameter model of the occupant-vehicle system. The optimal kinematics of the occupant in frontal impact is studied. The optimal characteristics of ... |
|
| Introduction to Violent Sun-Earth Connection Events of October-November 2003 |
30 SEP 2005 |
7 pages |
| Authors:
N. Gopalswamy; L. Barbieri; E. W. Cliver; G. Lu; S. P. Plunkett; R. M. Skoug; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| The violent solar eruptions of October-November 2003 are one of the best observed outbreaks of intense solar activity to date. These events, referred to as the Halloween storms, are extreme events in terms of both their source properties at the Sun and their heliospheric consequences. The plasma, particle, and electromagnetic consequences of these events were detected at several locations in the heliosphere thanks to the distributed network of spacecraft. Disturbances ... |
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| Deployable Hexapod Using Tape-Springs |
13 JUL 2005 |
8 pages |
| Authors:
Laurent Blanchard; Frederic Falzon; Jean Dupuis; Jean-Pierre Merlet; ALCATEL SPACE INDUSTRIES CANNES LA BOCCA (FRANCE)
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| In the near future of space observation systems several technical challenges come into light like multi-pupil systems conceived as free flyers or extremely high resolution (EHR) systems with large dimensions and high agility requirements. To be able to face these challenges the Alcatel Space Research Department is studying innovative structural concepts for future observation instruments. One of these concepts is based on an hexapod whose legs are deployable coiled tape-springs. ... |
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| Stars in the USNO-B1 Catalog with Proper Motions between 1.0 and 5.0 Arcseconds Per Year |
22 MAR 2005 |
43 pages |
| Authors:
Stephen E. Levine; NAVAL OBSERVATORY FLAGSTAFF AZ
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| This paper examines a subset of objects from the USNO-B1 catalogue with listed proper motions between 1.0 and 5.0 arcseconds per year. We look at the degree of contamination within this range of proper motions, and point out the major sources of spurious high proper motion objects. Roughly 0.1% of the objects in the USNO-B1 catalogue with listed motions between 1.0 and 5.0 arcseconds per year are real. Comparison with ... |
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