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Sample records for celestial navigation

  1. Celestial navigation in a nutshell

    CERN Document Server

    Schlereth, Hewitt

    2000-01-01

    Celestial Navigation in a Nutshell demonstrates how to take sights by the sun, moon, stars, and planets, discussing the advantages and disadvantages of each method. The reader is taken carefully through several examples and situational illustrations, making this a most effective self-teaching guide. Common errors are reviewed and several tips on how to improve accuracy are given.

  2. Celestial Navigation for the Novice

    Science.gov (United States)

    Sadler, Philip M.

    2011-01-01

    What kinds of astronomical lab activities can introductory astronomy students carry out easily in daytime? The most impressive is the determination of their latitude and longitude from observations of the sun. The "shooting of a noon sight” and its "reduction to a position” is a technique still practiced by navigators in this age of GPS. Indeed, the U.S. Coast Guard exams for ocean-going licenses and include celestial navigation. These techniques continue to be used by the military and by private sailors as a backup to electronic navigation systems. We present a method to establish one's latitude and longitude to better than 30 miles from measurements of the sun's altitude that is easily within the capability non-science majors. This is a practical application of astronomy in use the world over. The streamlined method used is based on an easy-to-build protractor and string quadrant. Participants will leave with all materials to conduct this activity in their own classroom.

  3. Daytime Celestial Navigation for the Novice

    Science.gov (United States)

    Sadler, Philip M.; Night, Christopher

    2010-03-01

    What kinds of astronomical lab activities can high school and college astronomy students carry out easily in daytime? The most impressive is the determination of latitude and longitude from observations of the Sun. The ``shooting of a noon sight'' and its ``reduction to a position'' grew to become a daily practice at the start of the 19th century1 following the perfection of the marine chronometer by John Harrison and its mass production.2 This technique is still practiced by navigators in this age of GPS. Indeed, the U.S. Coast Guard exams for ocean-going licenses include celestial navigation.3 These techniques continue to be used by the military and by private sailors as a backup to all-too-fallible and jammable electronic navigation systems. A sextant, a nautical almanac,4 special sight reduction tables,5 and involved calculations are needed to determine position to the nearest mile using the Sun, Moon, stars, or planets. Yet, finding latitude and longitude to better than 30 miles from measurements of the Sun's altitude is easily within the capability of those taking astronomy or physics for the first time by applying certain basic principles. Moreover, it shows a practical application of astronomy in use the world over. The streamlined method described here takes advantage of the similar level of accuracy of its three components: 1.Observations using a homemade quadrant6 (instead of a sextant), 2. Student-made graphs of the altitude of the Sun over a day7 (replacing lengthy calculation using sight reduction tables), and 3. An averaged 20-year analemma used to find the Sun's navigational coordinates8,9 (rather than the 300+ page Nautical Almanac updated yearly).

  4. Celestial Navigation in the USA, Fiji, and Tunisia

    Science.gov (United States)

    Holbrook, Jarita C.

    2015-05-01

    Today there are many coastal communities that are home to navigators who use stars for position finding at night; I was, however, unaware of this fact when I began researching celestial navigation practices in 1997. My project focused on three communities: the Moce Islanders of Fiji, the Kerkennah Islanders in Tunisia, and the U.S. Navy officers and students at the United States Naval Academy, Annapolis, Maryland. My goal was to answer the question of why people continue to navigate by the stars, but also to understand the role of technology in their navigation practices. Using anthropology techniques of ethnography including participant observation, formal and informal interviews, audio and videotaping, I gathered data over five years at the three communities. I began by learning the details of how they use the stars for navigation. Next, I learned about who did the navigation and where they learned to navigate. I gathered opinions on various navigation aids and instruments, and opinions about the future of using the stars for navigation. I listened to the stories that they told about navigating. In the United States I worked in English, in Fiji, in Fijian and English, and in Tunisia, French and English. For the formal interviews I worked with translators. The navigators use stars for navigating today but the future of their techniques is not certain. Though practiced today, these celestial navigation traditions have undergone and continue to undergo changes. New navigational technologies are part of the stimulation for change, thus 'a meeting of different worlds' is symbolized by peoples encounters with these technologies.

  5. Advanced Spacecraft Navigation and Timing Using Celestial Gamma-Ray Sources Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed novel program will use measurements of the high-energy photon output from gamma-ray celestial sources to design a new, unique navigation system. This...

  6. Celestial Navigation Fix Based on Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Tsou Ming-Cheng

    2015-09-01

    Full Text Available A technique for solving celestial fix problems is proposed in this study. This method is based on Particle Swarm Optimization from the field of swarm intelligence, utilizing its superior optimization and searching abilities to obtain the most probable astronomical vessel position. In addition to being applicable to two-body fix, multi-body fix, and high-altitude observation problems, it is also less reliant on the initial dead reckoning position. Moreover, by introducing spatial data processing and display functions in a Geographical Information System, calculation results and chart work used in Circle of Position graphical positioning can both be integrated. As a result, in addition to avoiding tedious and complicated computational and graphical procedures, this work has more flexibility and is more robust when compared to other analytical approaches.

  7. IN-FLIGHT ALIGNMENT OF INERTIAL NAVIGATION SYSTEM BY CELESTIAL OBSERVATION TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    ALlJamshaid; FANGJian-cheng

    2005-01-01

    This paper presents an in-flight alignment technique for a strapdown inertial navigation system (SINS) and employs a star pattern recognition procedure for identifying stars sensed by a CCD electrooptical star sensor.Collinearity equations are used to estimate sensor frame star coordinates and the conventional least square differential correction method is used to estimate the unknown orientation angles. A comparison of this attitude with the attitude estimated by the SINS provides axis misalignment angles. Simulations using a Kalman filter are carried out for an SINS and the system employs a local level navigation frame. The space stabilized SINS is discussed in conjunction with the celestial aiding. Based on the observation of the Kalman filter, the estimating and compensating gyro errors, as well as the position and velocity errors caused by the SINS misalignments are calibrated by celestial attitute information.

  8. Optimization design about gimbal structure of high-precision autonomous celestial navigation tracking mirror system

    Science.gov (United States)

    Huang, Wei; Yang, Xiao-xu; Han, Jun-feng; Wei, Yu; Zhang, Jing; Xie, Mei-lin; Yue, Peng

    2016-01-01

    High precision tracking platform of celestial navigation with control mirror servo structure form, to solve the disadvantages of big volume and rotational inertia, slow response speed, and so on. It improved the stability and tracking accuracy of platform. Due to optical sensor and mirror are installed on the middle-gimbal, stiffness and resonant frequency requirement for high. Based on the application of finite element modality analysis theory, doing Research on dynamic characteristics of the middle-gimbal, and ANSYS was used for the finite element dynamic emulator analysis. According to the result of the computer to find out the weak links of the structure, and Put forward improvement suggestions and reanalysis. The lowest resonant frequency of optimization middle-gimbal avoid the bandwidth of the platform servo mechanism, and much higher than the disturbance frequency of carrier aircraft, and reduces mechanical resonance of the framework. Reaching provides a theoretical basis for the whole machine structure optimization design of high-precision of autonomous Celestial navigation tracking mirror system.

  9. A Ka-band Celestial Reference Frame with Applications to Deep Space Navigation

    Science.gov (United States)

    Jacobs, Christopher S.; Clark, J. E.; García-Miró, C.; Horiuchi, S.; Sotuela, I.

    2011-10-01

    The Ka-band radio spectrum is now being used for a wide variety of applications. This paper highlights the use of Ka-band as a frequency for precise deep space navigation based on a set of reference beacons provided by extragalactic quasars which emit broadband noise at Ka-band. This quasar-based celestial reference frame is constructed using X/Ka-band (8.4/32 GHz) from fifty-five 24-hour sessions with the Deep Space Network antennas in California, Australia, and Spain. We report on observations which have detected 464 sources covering the full 24 hours of Right Ascension and declinations down to -45 deg. Comparison of this X/Ka-band frame to the international standard S/X-band (2.3/8.4 GHz) ICRF2 shows wRMS agreement of ~200 micro-arcsec (μas) in α cos δ and ~300 μas in δ. There is evidence for systematic errors at the 100 μas level. Known errors include limited SNR, lack of instrumental phase calibration, tropospheric refraction mis-modeling, and limited southern geometry. The motivation for extending the celestial reference frame to frequencies above 8 GHz is to access more compact source morphology for improved frame stability and to support spacecraft navigation for Ka-band based NASA missions.

  10. A Ka-Band Celestial Reference Frame with Applications to Deep Space Navigation

    Science.gov (United States)

    Jacobs, Christopher S.; Clark, J. Eric; Garcia-Miro, Cristina; Horiuchi, Shinji; Sotuela, Ioana

    2011-01-01

    The Ka-band radio spectrum is now being used for a wide variety of applications. This paper highlights the use of Ka-band as a frequency for precise deep space navigation based on a set of reference beacons provided by extragalactic quasars which emit broadband noise at Ka-band. This quasar-based celestial reference frame is constructed using X/Ka-band (8.4/32 GHz) from fifty-five 24-hour sessions with the Deep Space Network antennas in California, Australia, and Spain. We report on observations which have detected 464 sources covering the full 24 hours of Right Ascension and declinations down to -45 deg. Comparison of this X/Ka-band frame to the international standard S/X-band (2.3/8.4 GHz) ICRF2 shows wRMS agreement of approximately 200 micro-arcsec in alpha cos(delta) and approximately 300 micro-arcsec in delta. There is evidence for systematic errors at the 100 micro-arcsec level. Known errors include limited SNR, lack of instrumental phase calibration, tropospheric refraction mis-modeling, and limited southern geometry. The motivation for extending the celestial reference frame to frequencies above 8 GHz is to access more compact source morphology for improved frame stability and to support spacecraft navigation for Ka-band based NASA missions.

  11. Dual-EKF-Based Real-Time Celestial Navigation for Lunar Rover

    Directory of Open Access Journals (Sweden)

    Li Xie

    2012-01-01

    Full Text Available A key requirement of lunar rover autonomous navigation is to acquire state information accurately in real-time during its motion and set up a gradual parameter-based nonlinear kinematics model for the rover. In this paper, we propose a dual-extended-Kalman-filter- (dual-EKF- based real-time celestial navigation (RCN method. The proposed method considers the rover position and velocity on the lunar surface as the system parameters and establishes a constant velocity (CV model. In addition, the attitude quaternion is considered as the system state, and the quaternion differential equation is established as the state equation, which incorporates the output of angular rate gyroscope. Therefore, the measurement equation can be established with sun direction vector from the sun sensor and speed observation from the speedometer. The gyro continuous output ensures the algorithm real-time operation. Finally, we use the dual-EKF method to solve the system equations. Simulation results show that the proposed method can acquire the rover position and heading information in real time and greatly improve the navigation accuracy. Our method overcomes the disadvantage of the cumulative error in inertial navigation.

  12. Autonomous navigation method of high elliptical orbit satellite based on celestial navigation and GPS%基于天文/GPS的HEO卫星自主导航方法

    Institute of Scientific and Technical Information of China (English)

    王鹏; 张迎春

    2015-01-01

    为了实现大椭圆轨道(HEO)卫星高精度自主导航,提出一种将直接敏感地平天文导航与全球定位系统(GPS)相结合的组合导航方法.首先,分析卫星轨道��2运动模型及其所受空间摄动,建立卫星轨道动力学模型;然后,分析单一使用天文导航和GPS的优缺点,根据HEO卫星对GPS的可见性,提出在远地点只采用天文导航,而在近地点采用以天文导航为主、适时引入GPS信号进行位速测量辅助修正的方法.通过计算机仿真和结果分析表明了所提出的设计方法导航精度比单一天文导航提高72.4%∼85.6%.%In order to realize autonomous and continuous navigation information outputs for high elliptical orbit(HEO) satellite, new integrated navigation system is proposed based on celestial navigation of directly sensing stellar and global positioning system(GPS) navigation. Firstly, satellite orbit motion model is established on the satellite orbit dynamics��2 model and suffered space perturbation. Moreover, performances of single-use celestial navigation or GPS are analyzed. When the satellite is near the apogee, observation system is established by using only celestial navigation. When the satellite is near the perigee, the estimate covariance is revised through incoming GPS signal to improve the celestial navigation estimate. The autonomous navigation system is designed and simulating. The results of computer simulation show that the navigation accuracy is improved by 72.4%∼85.6%compared with the celestial navigation method.

  13. Method and System for Gamma-Ray Localization Induced Spacecraft Navigation Using Celestial Gamma-Ray Sources

    Science.gov (United States)

    Sheikh, Suneel I. (Inventor); Hisamoto, Chuck (Inventor); Arzoumanian, Zaven (Inventor)

    2015-01-01

    A method and system for spacecraft navigation using distant celestial gamma-ray bursts which offer detectable, bright, high-energy events that provide well-defined characteristics conducive to accurate time-alignment among spatially separated spacecraft. Utilizing assemblages of photons from distant gamma-ray bursts, relative range between two spacecraft can be accurately computed along the direction to each burst's source based upon the difference in arrival time of the burst emission at each spacecraft's location. Correlation methods used to time-align the high-energy burst profiles are provided. The spacecraft navigation may be carried out autonomously or in a central control mode of operation.

  14. Celestial X-ray Source Modeling and Catalogues for Spacecraft Navigation and Timing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Microcosm X-ray pulsar-based navigation and timing (XNAV) team will provide the software and modeling infrastructure for NASA to support XNAV operations,...

  15. Automatic Solar and Celestial Navigation on the Moon and Mars Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Micro-Space proposes to develop a low mass, automated form of the classic navigator's bubble sextant, with no moving parts, for rapid localization and reliable...

  16. Celestial Treasury

    Science.gov (United States)

    Lachièze-Rey, Marc; Luminet, Jean-Pierre

    2001-07-01

    Throughout history, the mysterious dark skies have inspired our imaginations in countless ways, influencing our endeavors in science and philosophy, religion, literature, and art. Filled with 380 full-color illustrations, Celestial Treasury shows the influence of astronomical theories and the richness of illustrations in Western civilization through the ages. The authors explore the evolution of our understanding of astronomy and weave together ancient and modern theories in a fascinating narrative. They incorporate a wealth of detail from Greek verse, medieval manuscripts and Victorian poetry with contemporary spacecraft photographs and computer-generated star charts. Celestial Treasury is more than a beautiful book: it answers a variety of questions that have intrigued scientists and laymen for centuries. -- How did philosophers and scientists try to explain the order that governs celestial motion? -- How did geometers and artists measure and map the skies? -- How many different answers have been proposed for the most fundamental of all questions: When and how did Earth come about? -- Who inhabits the heavens--gods, angels or extraterrestrials? No other book recounts humankind's fascination with the heavens as compellingly as Celestial Treasury. Marc Lachièze-Rey is a director of research at the Centre National pour la Récherche Scientifique and astrophysicist at the Centre d'Etudes de Saclay. He is the author of The Cosmic Background Radiation (Cambridge, 1999), and and The Quest for Unity, (Oxford, 1999 ), as well as many books in French. Jean-Pierre Luminet is a research director of the Centre National pour la Rechérche Scientifique, based at the Paris-Meudon observatory. He is the author of Black Holes, (Cambridge 1992), as well as science documentaries for television.

  17. Celestial polarization patterns sufficient for Viking navigation with the naked eye: detectability of Haidinger's brushes on the sky versus meteorological conditions.

    Science.gov (United States)

    Horváth, Gábor; Takács, Péter; Kretzer, Balázs; Szilasi, Szilvia; Száz, Dénes; Farkas, Alexandra; Barta, András

    2017-02-01

    If a human looks at the clear blue sky from which light with high enough degree of polarization d originates, an 8-shaped bowtie-like figure, the yellow Haidinger's brush can be perceived, the long axis of which points towards the sun. A band of high d arcs across the sky at 90° from the sun. A person can pick two points on that band, observe the yellow brushes and triangulate the position of the sun based on the orientation of the two observed brushes. This method has been suggested to have been used on the open sea by Viking navigators to determine the position of the invisible sun occluded by cloud or fog. Furthermore, Haidinger's brushes can also be used to locate the sun when it is below the horizon or occluded by objects on the horizon. To determine the position of the sun using the celestial polarization pattern, the d of the portion of the sky used must be greater than the viewer's degree of polarization threshold d* for perception of Haidinger's brushes. We studied under which sky conditions the prerequisite d > d* is satisfied. Using full-sky imaging polarimetry, we measured the d-pattern of skylight in the blue (450 nm) spectral range for 1296 different meteorological conditions with different solar elevation angles θ and per cent cloud cover ρ. From the measured d-patterns of a given sky we determined the proportion P of the sky for which d > d*. We obtained that P is the largest at low solar elevations θ ≈ 0° and under totally or nearly clear skies with cloud coverage ρ = 0%, when the sun's position is already easily determined. If the sun is below the horizon (-5° ≤ θ sky conditions. Consequently, the sky-polarimetric Viking navigation based on Haidinger's brushes is most useful after sunset and prior to sunrise, when the sun is not visible and large sky regions are bright, clear and polarized enough for perception of Haidinger's brushes.

  18. Methods of celestial mechanics

    CERN Document Server

    Brouwer, Dirk

    2013-01-01

    Methods of Celestial Mechanics provides a comprehensive background of celestial mechanics for practical applications. Celestial mechanics is the branch of astronomy that is devoted to the motions of celestial bodies. This book is composed of 17 chapters, and begins with the concept of elliptic motion and its expansion. The subsequent chapters are devoted to other aspects of celestial mechanics, including gravity, numerical integration of orbit, stellar aberration, lunar theory, and celestial coordinates. Considerable chapters explore the principles and application of various mathematical metho

  19. IN-FLIGHT ALIGNMENT OF INERTIAL NAVIGATION SYSTEM BY CELESTIAL OBSERVATION TECHNIQUE%基于天文观测技术的惯性导航系统的空中对准

    Institute of Scientific and Technical Information of China (English)

    阿里·捷木思; 房建成

    2005-01-01

    This paper presents an in-flight alignment technique for a strapdown inertial navigation system (SINS) and employs a star pattern recognition procedure for identifying stars sensed by a CCD electrooptical star sensor. Collinearity equations are used to estimate sensor frame star coordinates and the conventional least square differ-ential correction method is used to estimate the unknown orientation angles. A comparison of this attitude with the attitude estimated by the SINS provides axis misalignment angles. Simulations using a Kalman filter are carried out for an SINS and the system employs a local level navigation frame. The space stabilized SINS is discussed in conjunction with the celestial aiding. Based on the observation of the Kalman filter, the estimating and compensating gyro errors, as well as the position and velocity errors caused by the SINS misalignments are calibrated by celestial attitute information.%提出了一种基于CCD星敏感器的捷联惯性导航系统的空中对准方法.应用双线性方程求解被观测星在星敏感器坐标系中的坐标值及传统最小二乘微分校正法求解捷联惯性导航的姿态,该姿态值与捷联惯性导航解算姿态的差值就是惯性导航系统的失准角.作为Kalman滤波器的观测量,计算机仿真结果表明,天文姿态信息有效地校正了陀螺漂移和初始失准角引起的位置和速度误差.

  20. 天文角度辅助的高超声速飞行器多信息融合导航算法%Multi-information fusion navigation algorithm assisted by celestial angle observation for hypersonic cruise vehicle

    Institute of Scientific and Technical Information of China (English)

    王融; 熊智; 刘建业; 钟丽娜

    2013-01-01

    The traditional inertial/celestial integrated navigation system (INS/CNS) is inapplicable for hypersonic vehicle, because it can’t work under the body coordinate accordance and single-star visible condition. In this paper, a tightly-coupled INS/GPS/CNS integrated navigation scheme for hypersonic vehicle is investigated. The new INS/CNS integrated model is built based on transformational relation between starlight elevation/azimuth and INS errors. The new model can stabilize the measurement noise characteristic and work under single-star visible condition, thus can improve the continuity and accuracy of INS/CNS integration. The simulation of hypersonic vehicle navigation indicates that, the system assisted by celestial angle observation shows 60%-70% improvement in attitude accuracy than the unassisted system.%常规惯性/天文组合导航方法难以直接应用于高超声速飞行器机载环境下以载体系为基准进行星光测量的情况,且在可见星只有一颗时无法连续组合。为此,构建了高超声速飞行器惯性/卫星/天文紧组合导航系统方案,通过分析载体系下星光仰角、方位角与惯导误差之间的转换关系,建立了载体系下惯性/天文角度组合模型。理论分析表明,该系统在只有一颗导航星时仍能辅助惯导工作,且可使观测噪声特性保持稳定,从而提高了天文对惯导辅助的连续性和组合滤波估计精度。仿真结果表明,在高超声速飞行器导航系统采用天文角度辅助后,姿态误差较无天文辅助情况的降低60%~70%。

  1. Burnham's celestial handbook

    CERN Document Server

    Burnham, Robert

    1978-01-01

    Volume II of a comprehensive three-part guide to celestial objects outside our solar system ranges from Chamaeleon to Orion. Features coordinates, classifications, physical descriptions, hundreds of visual aids. 1977 edition.

  2. Burnham's celestial handbook

    CERN Document Server

    Burnham, Robert

    1978-01-01

    Volume I of this comprehensive three-part guide to the thousands of celestial objects outside our solar system ranges from Andromeda through Cetus. Objects are grouped according to constellation, and their definitions feature names, coordinates, classifications, and physical descriptions. Additional notes offer fascinating historical information. Hundreds of visual aids. 1977 edition.

  3. Burnham's celestial handbook

    CERN Document Server

    Burnham, Robert

    1978-01-01

    Volume III of this three-part comprehensive guide to the thousands of celestial objects outside our solar system concludes with listings from Pavo through Vulpecula. Objects are grouped according to constellation, and their definitions feature names, coordinates, classifications, and physical descriptions. Additional notes offer fascinating historical information. Hundreds of visual aids. 1977 edition.

  4. 基于非开普勒轨道的高超声速临近空间飞行器自主天文导航研究%Study on the Autonomous Celestial Navigation of Near Space Vehicles With Hypersonic Speed Based on Non-Keplerian Orbits

    Institute of Scientific and Technical Information of China (English)

    李海林; 吴德伟

    2012-01-01

    针对航天器自主导航方法不适合高超声速临近空间飞行器的问题,研究了基于非开普勒轨道的高超声速临近空间飞行器自主天文导航方案.论述了基于非开普勒轨道的自主天文导航机理,通过对高超声速临近空间飞行器受力分析,建立了动力学方程;利用矢量倒数法则推导出空间运动方程;设计了基于非开普勒轨道的状态模型和基于星光折射间接敏感地平的观测模型,采用卡尔曼滤波进行了仿真验证.仿真结果表明,基于非开普勒轨道的高超声速临近空间飞行器自主天文导航可达到较高的位置和速度精度.%In allusion to the problem that the aircraft autonomous celestial navigation is not suitable for the near space vehicles with hypersonic speed, an approach of the autonomous celestial navigation of near space vehicles with hypersonic speed based on non-Keplerian orbits is studied. Mechanism of the autonomous celestial navigation based on non-Keplerian is analyzed, and the dynamic equations are developed by analyzing the strength of near space vehicles with hypersonic speed. The space motion equation is educed using the vector derivatives rules. States model based on non-Keplerian orbits and measurement model using the concept of stellar horizon atmospheric refraction are de- signed, and the Kalman filter simulation is adopted. Results show that the autonomous celestial navigation of near space vehicles with hypersonic speed based on non-Keplerian orbits can meet the requirement of high precision for position and velocity, which is important for further research on the near space vehicles with hypersonic speed.

  5. Frontiers in relativistic celestial mechanics

    CERN Document Server

    2014-01-01

    Relativistic celestial mechanics – investigating the motion celestial bodies under the influence of general relativity – is a major tool of modern experimental gravitational physics. With a wide range of prominent authors from the field, this two-volume series consists of reviews on a multitude of advanced topics in the area of relativistic celestial mechanics – starting from more classical topics such as the regime of asymptotically-flat spacetime, light propagation and celestial ephemerides, but also including its role in cosmology and alternative theories of gravity as well as modern experiments in this area.

  6. Pulsar/CNS integrated navigation based on federated UKF

    Institute of Scientific and Technical Information of China (English)

    Jin Liu; Jie Ma; Jinwen Tian

    2010-01-01

    In order to improve the autonomous navigation capability of satellite,a pulsar/CNS(celestial navigation system)integrated navigation method based on federated unscented Kalman filter(UKF)is proposed.The celestial navigation is a mature and stable navigation method.However,its position determination performance is not satisfied due to the low accuracy of horizon sensor.Single pulsar navigation is a new navigation method,which can provide highly accurate range measurements.The major drawback of single pulsar navigation is that the system is completely unobservabie.As two methods are complementary to each other,the federated UKF is used here for fusing the navigation data from single pulsar navigation and CNS.Compared to the traditional celestial navigation method and single pulsar navigation,the integrated navigation method can provide better navigation performance.The simulation results demonstrate the feasibility and effectiveness of the navigation method.

  7. A Celestial Assisted INS Initialization Method for Lunar Explorers

    Directory of Open Access Journals (Sweden)

    Jiancheng Fang

    2011-07-01

    Full Text Available The second and third phases of the Chinese Lunar Exploration Program (CLEP are planning to achieve Moon landing, surface exploration and automated sample return. In these missions, the inertial navigation system (INS and celestial navigation system (CNS are two indispensable autonomous navigation systems which can compensate for limitations in the ground based navigation system. The accurate initialization of the INS and the precise calibration of the CNS are needed in order to achieve high navigation accuracy. Neither the INS nor the CNS can solve the above problems using the ground controllers or by themselves on the lunar surface. However, since they are complementary to each other, these problems can be solved by combining them together. A new celestial assisted INS initialization method is presented, in which the initial position and attitude of the explorer as well as the inertial sensors’ biases are estimated by aiding the INS with celestial measurements. Furthermore, the systematic error of the CNS is also corrected by the help of INS measurements. Simulations show that the maximum error in position is 300 m and in attitude 40″, which demonstrates this method is a promising and attractive scheme for explorers on the lunar surface.

  8. The geometry of celestial mechanics

    CERN Document Server

    Geiges, Hansjörg

    2016-01-01

    Celestial mechanics is the branch of mathematical astronomy devoted to studying the motions of celestial bodies subject to the Newtonian law of gravitation. This mathematical introductory textbook reveals that even the most basic question in celestial mechanics, the Kepler problem, leads to a cornucopia of geometric concepts: conformal and projective transformations, spherical and hyperbolic geometry, notions of curvature, and the topology of geodesic flows. For advanced undergraduate and beginning graduate students, this book explores the geometric concepts underlying celestial mechanics and is an ideal companion for introductory courses. The focus on the history of geometric ideas makes it perfect supplementary reading for students in elementary geometry and topology. Numerous exercises, historical notes and an extensive bibliography provide all the contextual information required to gain a solid grounding in celestial mechanics.

  9. An introduction to celestial mechanics

    CERN Document Server

    Moulton, Forest Ray

    1984-01-01

    An unrivaled text in the field of celestial mechanics, Moulton's theoretical work on the prediction and interpretation of celestial phenomena has not been superseded. By providing a general account of all parts of celestial mechanics without an over-full treatment of any single aspect, by stating all the problems in advance, and, where the transformations are long, giving an outline of the steps which must be made, and by noting all the places where assumptions have been introduced or unjustified methods employed, Moulton has insured that his work will be valuable to all who are interested in

  10. Celestial data routing network

    Science.gov (United States)

    Bordetsky, Alex

    2000-11-01

    Imagine that information processing human-machine network is threatened in a particular part of the world. Suppose that an anticipated threat of physical attacks could lead to disruption of telecommunications network management infrastructure and access capabilities for small geographically distributed groups engaged in collaborative operations. Suppose that small group of astronauts are exploring the solar planet and need to quickly configure orbital information network to support their collaborative work and local communications. The critical need in both scenarios would be a set of low-cost means of small team celestial networking. To the geographically distributed mobile collaborating groups such means would allow to maintain collaborative multipoint work, set up orbital local area network, and provide orbital intranet communications. This would be accomplished by dynamically assembling the network enabling infrastructure of the small satellite based router, satellite based Codec, and set of satellite based intelligent management agents. Cooperating single function pico satellites, acting as agents and personal switching devices together would represent self-organizing intelligent orbital network of cooperating mobile management nodes. Cooperative behavior of the pico satellite based agents would be achieved by comprising a small orbital artificial neural network capable of learning and restructing the networking resources in response to the anticipated threat.

  11. The Celestial Basis of Civilization

    Science.gov (United States)

    Masse, W. B.

    Scholars have long puzzled over the reasons for the ubiquity of celestial images in the residue of the world's earliest civilizations: in art, myth, religious cosmology, iconography, cosmogony, eschatological beliefs, and as portents for the conduct of royal and chiefly power. The general consensus is that these images represented a need by early societies to use the fixed celestial heavens in order to regulate ritual and agricultural cycles, and to satisfy a psychological need by people to relate themselves to their surrounding Universe. Such explanations are facile and miss an important aspect of the celestial heavens. The fixed celestial heavens served as the back-drop for a large number of often spectacular temporary naked-eye visible celestial events which animated the night and sometimes the daytime sky, and which created an 'otherworld' for virtually all cultural groups. In this paper I present a model derived from the detailed analysis of Hawaiian oral traditions and culture history in relation to historic astronomical records of temporary celestial events, and then apply this model to cultural traditions from Mesoamerica and other geographic regions in order to demonstrate that novae, supernovae, variable stars, comets, great meteor showers, aurorae, solar and lunar eclipses, and impacting Solar System debris, together played a critical role in the artistic, intellectual, and political development of early civilizations. These data not only provide important insights into the development of civilization, but also provide important details and longitudinal records of astronomical events and phenomena which are otherwise not readily available for scientific scrutiny.

  12. Combining sky and earth: desert ants (Melophorus bagoti) show weighted integration of celestial and terrestrial cues.

    Science.gov (United States)

    Legge, Eric L G; Wystrach, Antoine; Spetch, Marcia L; Cheng, Ken

    2014-12-01

    Insects typically use celestial sources of directional information for path integration, and terrestrial panoramic information for view-based navigation. Here we set celestial and terrestrial sources of directional information in conflict for homing desert ants (Melophorus bagoti). In the first experiment, ants learned to navigate out of a round experimental arena with a distinctive artificial panorama. On crucial tests, we rotated the arena to create a conflict between the artificial panorama and celestial information. In a second experiment, ants at a feeder in their natural visually-cluttered habitat were displaced prior to their homing journey so that the dictates of path integration (feeder to nest direction) based on a celestial compass conflicted with the dictates of view-based navigation (release point to nest direction) based on the natural terrestrial panorama. In both experiments, ants generally headed in a direction intermediate to the dictates of celestial and terrestrial information. In the second experiment, the ants put more weight on the terrestrial cues when they provided better directional information. We conclude that desert ants weight and integrate the dictates of celestial and terrestrial information in determining their initial heading, even when the two directional cues are highly discrepant.

  13. PulsarPlane: a feasibility study for millisecond radio pulsar navigation

    NARCIS (Netherlands)

    Buist, Peter; Hesselink, Henk; Gibbs, Alex; Keuning, Michel; Gaubitch, Nikolay; Noroozi, Arash; Verhoeven, Chris; Heusdens, Richard; Fernandes, Jorge; Kabakchiev, Hristo; Bentum, Mark; Kestilä, Antti

    2014-01-01

    Stars have been used -in what is called celestial navigation- since thousands of years by mankind. Celestial navigation was used extensively in aviation until the 1960s, and in marine navigation until recently. It has been investigated for agriculture applications, utilized for military aircraft and

  14. Observation of Celestial Phenomena in Ancient China

    Science.gov (United States)

    Sun, Xiaochun

    Because of the need for calendar-making and portent astrology, the Chinese were diligent and meticulous observers of celestial phenomena. China has maintained the longest continuous historical records of celestial phenomena in the world. Extraordinary or abnormal celestial events were particularly noted because of their astrological significance. The historical records cover various types of celestial phenomena, which include solar and lunar eclipses, sunspots, "guest stars" (novae or supernovae as we understand today), comets and meteors, and all kinds of planetary phenomena. These records provide valuable historical data for astronomical studies today.

  15. An elementary survey of celestial mechanics

    CERN Document Server

    Ryabov, Y

    2006-01-01

    An accessible exposition of gravitation theory and celestial mechanics, this classic, oft-cited work was written by a distinguished Soviet astronomer. It explains with exceptional clarity the methods used by physicists in studying celestial phenomena.A historical introduction explains the Ptolemaic view of planetary motion and its displacement by the studies of Copernicus, Kepler, and Newton. Succeeding chapters examine the making of celestial observations and measurements and explain such central concepts as the ecliptic, the orbital plane, the two- and three-body problems, and perturbed moti

  16. The Inner Meaning of Outer Space: Human Nature and the Celestial Realm

    Directory of Open Access Journals (Sweden)

    Timothy L. Hubbard

    2008-06-01

    Full Text Available Kant argued that humans possess a priori knowledge of space; although his argument focused on a physics of bodies, it also has implications for a psychology of beings. Many human cultures organize stars in the night sky into constellations (i.e., impose structure; attribute properties, behaviors, and abilities to objects in the celestial realm (i.e., impose meaning; and use perceived regularity in the celestial realms in development of calendars, long-range navigation, agriculture, and astrology (i.e., seek predictability and control. The physical inaccessibility of the celestial realm allows a potent source of metaphor, and also allows projection of myths regarding origin and ascension, places of power, and dwelling places of gods, immortals, and other souls. Developments in astronomy and cosmology infl uenced views of human nature and the place of humanity in the universe, and these changes parallel declines in egocentrism with human development. Views regarding alleged beings (e.g., angels, extraterrestrials from the celestial realm (and to how communicate with such beings are anthropocentric and ignore evolutionary factors in physical and cognitive development. It is suggested that in considering views and uses of the celestial realm, we learn not just about the universe, but also about ourselves. *

  17. Connecting VLBI and Gaia celestial reference frames

    CERN Document Server

    Malkin, Zinovy

    2016-01-01

    The current state of the link problem between radio and optical celestial reference frames is considered. The main objectives of the investigations in this direction during the next few years are the preparation of a comparison and the mutual orientation and rotation between the optical {\\it Gaia} Celestial Reference Frame (GCRF) and the 3rd generation radio International Celestial Reference Frame (ICRF3), obtained from VLBI observations. Both systems, ideally, should be a realization of the ICRS (International Celestial Reference System) at micro-arcsecond level accuracy. Therefore, the link accuracy between the ICRF and GCRF should be obtained with similar error level, which is not a trivial task due to relatively large systematic and random errors in source positions at different frequency bands. In this paper, a brief overview of recent work on the GCRF--ICRF link is presented. Additional possibilities to improve the GCRF--ICRF link accuracy are discussed. The suggestion is made to use astrometric radio s...

  18. Celestial mechanics and astrodynamics theory and practice

    CERN Document Server

    Gurfil, Pini

    2016-01-01

    This volume is designed as an introductory text and reference book for graduate students, researchers and practitioners in the fields of astronomy, astrodynamics, satellite systems, space sciences and astrophysics. The purpose of the book is to emphasize the similarities between celestial mechanics and astrodynamics, and to present recent advances in these two fields so that the reader can understand the inter-relations and mutual influences. The juxtaposition of celestial mechanics and astrodynamics is a unique approach that is expected to be a refreshing attempt to discuss both the mechanics of space flight and the dynamics of celestial objects. “Celestial Mechanics and Astrodynamics: Theory and Practice” also presents the main challenges and future prospects for the two fields in an elaborate, comprehensive and rigorous manner. The book presents homogenous and fluent discussions of the key problems, rendering a portrayal of recent advances in the field together with some basic concepts and essential in...

  19. Relativistic Celestial Mechanics of the Solar System

    Science.gov (United States)

    Kopeikin, Sergei; Efroimsky, Michael; Kaplan, George

    2011-09-01

    The general theory of relativity was developed by Einstein a century ago. Since then, it has become the standard theory of gravity, especially important to the fields of fundamental astronomy, astrophysics, cosmology, and experimental gravitational physics. Today, the application of general relativity is also essential for many practical purposes involving astrometry, navigation, geodesy, and time synchronization. Numerous experiments have successfully tested general relativity to a remarkable level of precision. Exploring relativistic gravity in the solar system now involves a variety of high-accuracy techniques, for example, very long baseline radio interferometry, pulsar timing, spacecraft Doppler tracking, planetary radio ranging, lunar laser ranging, the global positioning system (GPS), torsion balances and atomic clocks. Over the last few decades, various groups within the International Astronomical Union have been active in exploring the application of the general theory of relativity to the modeling and interpretation of high-accuracy astronomical observations in the solar system and beyond. A Working Group on Relativity in Celestial Mechanics and Astrometry was formed in 1994 to define and implement a relativistic theory of reference frames and time scales. This task was successfully completed with the adoption of a series of resolutions on astronomical reference systems, time scales, and Earth rotation models by the 24th General Assembly of the IAU, held in Manchester, UK, in 2000. However, these resolutions only form a framework for the practical application of relativity theory, and there have been continuing questions on the details of the proper application of relativity theory to many common astronomical problems. To ensure that these questions are properly addressed, the 26th General Assembly of the IAU, held in Prague in August 2006, established the IAU Commission 52, "Relativity in Fundamental Astronomy". The general scientific goals of the new

  20. A new method of single celestial-body sun positioning based on theory of mechanisms

    Institute of Scientific and Technical Information of China (English)

    Zhang Wei; Xu Xiaofeng; Wu Yuanzhe

    2016-01-01

    Considering defects of current single celestial-body positioning methods such as discon-tinuity and long period, a new sun positioning algorithm is herein put forward. Instead of tradi-tional astronomical spherical trigonometry and celestial coordinate system, the proposed new positioning algorithm is built by theory of mechanisms. Based on previously derived solar vector equations (from a C1R2P2 series mechanism), a further global positioning method is developed by inverse kinematics. The longitude and latitude coordinates expressed by Greenwich mean time (GMT) and solar vector in local coordinate system are formulated. Meanwhile, elimination method of multiple solutions, errors of longitude and latitude calculation are given. In addition, this algo-rithm has been integrated successfully into a mobile phone application to visualize sun positioning process. Results of theoretical verification and smart phone’s test demonstrate the validity of pre-sented coordinate’s expressions. Precision is shown as equivalent to current works and is acceptable to civil aviation requirement. This new method solves long-period problem in sun sight running fix-ing and improves applicability of sun positioning. Its methodology can inspire development of new sun positioning device. It would be more applicable to be combined with inertial navigation systems for overcoming discontinuity of celestial navigation systems and accumulative errors of inertial nav-igation systems.

  1. Relativistic Celestial Mechanics of the Solar System

    CERN Document Server

    Kopeikin, Sergei; Kaplan, George

    2011-01-01

    This authoritative book presents the theoretical development of gravitational physics as it applies to the dynamics of celestial bodies and the analysis of precise astronomical observations. In so doing, it fills the need for a textbook that teaches modern dynamical astronomy with a strong emphasis on the relativistic aspects of the subject produced by the curved geometry of four-dimensional spacetime. The first three chapters review the fundamental principles of celestial mechanics and of special and general relativity. This background material forms the basis for understanding relativistic r

  2. Connecting VLBI and Gaia celestial reference frames

    Directory of Open Access Journals (Sweden)

    Zinovy Malkin

    2016-09-01

    Full Text Available The current state of the link problem between radio and optical celestial reference frames is considered.The main objectives of the investigations in this direction during the next few years are the preparation of a comparisonand the mutual orientation and rotation between the optical it Gaia Celestial Reference Frame (GCRFand the 3rd generation radio International Celestial Reference Frame (ICRF3, obtained from VLBI observations.Both systems, ideally, should be a realization of the ICRS (International Celestial Reference System at micro-arcsecond level accuracy.Therefore, the link accuracy between the ICRF and GCRF should be obtained with similar error level, which is not a trivial taskdue to relatively large systematic and random errors in source positions at different frequency bands.In this paper, a brief overview of recent work on the GCRF--ICRF link is presented.Additional possibilities to improve the GCRF--ICRF link accuracy are discussed.The suggestion is made to use astrometric radio sources with optical magnitude to 20$^m$ rather than to 18$^m$ as currently plannedfor the GCRF--ICRF link.In addition, the use of radio stars is also a prospective method to obtain independent and accurate orientation between the Gaia frame and the ICRF.

  3. Orientation and navigation in birds

    Directory of Open Access Journals (Sweden)

    H. Bouwman

    1998-07-01

    Full Text Available How birds orientate and navigate over long distances, remains one of the subjects of ornithology eliciting much interest. Birds use combinations of different sources of information to find direction and position. Some of these are the geomagnetic field, celestial bodies, mosaic and gradient maps, sound, smell, idiotetic information and others. Different species use different combinations of sources. This ability is partially inherent and partially learned.

  4. Deep Space CubeSat Gamma-ray Navigation Technology Demonstration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed novel program will use measurements of high-energy photon output from celestial gamma-ray sources to design a new, unique navigation system for a deep...

  5. Orbital behavior around a nonuniform celestial body

    Science.gov (United States)

    Rosson, Z.; Hall, F.; Vogel, T.

    2016-09-01

    To effectively model the orbit around a nonuniform celestial body, detailed information needs to be determined of the perturbations. This research looked at one of the most crucial perturbations: the nonuniform gravitational field of a celestial body. Given an orbiting particle (a satellite), we utilized numerical methods to calculate its orbit in two dimensions around a discretized center mass structure. The gravitational acceleration imposed on the particle due to each mass point sums vectorally as the particle completes each infinitesimal time step of one orbit. There are noticeable effects on the orbit as the conditions of the center mass change. The development of a simulation code allows for the modelling of the orbit about an irregular body with satisfactory accuracy.

  6. Recent advances in celestial and space mechanics

    CERN Document Server

    Chyba, Monique

    2016-01-01

    This book presents recent advances in space and celestial mechanics, with a focus on the N-body problem and astrodynamics, and explores the development and application of computational techniques in both areas. It highlights the design of space transfers with various modes of propulsion, like solar sailing and low-thrust transfers between libration point orbits, as well as a broad range of targets and applications, like rendezvous with near Earth objects. Additionally, it includes contributions on the non-integrability properties of the collinear three- and four-body problem, and on general conditions for the existence of stable, minimum energy configurations in the full N-body problem. A valuable resource for physicists and mathematicians with research interests in celestial mechanics, astrodynamics and optimal control as applied to space transfers, as well as for professionals and companies in the industry.

  7. Beacons for supporting lunar landing navigation

    Science.gov (United States)

    Theil, Stephan; Bora, Leonardo

    2017-03-01

    Current and future planetary exploration missions involve a landing on the target celestial body. Almost all of these landing missions are currently relying on a combination of inertial and optical sensor measurements to determine the current flight state with respect to the target body and the desired landing site. As soon as an infrastructure at the landing site exists, the requirements as well as conditions change for vehicles landing close to this existing infrastructure. This paper investigates the options for ground-based infrastructure supporting the onboard navigation system and analyzes the impact on the achievable navigation accuracy. For that purpose, the paper starts with an existing navigation architecture based on optical navigation and extends it with measurements to support navigation with ground infrastructure. A scenario of lunar landing is simulated and the provided functions of the ground infrastructure as well as the location with respect to the landing site are evaluated. The results are analyzed and discussed.

  8. UPF based autonomous navigation scheme for deep space probe

    Institute of Scientific and Technical Information of China (English)

    Li Peng; Cui Hutao; Cui Pingyuan

    2008-01-01

    The autonomous "celestial navigation scheme" for deep space probe departing from the earth and the autonomous "optical navigation scheme" for encountering object celestial body are presented. Then, aiming at the conditions that large initial estimation errors and non-Gaussian distribution of state or measurement errors may exist in orbit determination process of the two phases, UPF (unscented particle filter) is introduced into the navigation schemes. By tackling nonlinear and non-Gaussian problems, UPF overcomes the accuracy influence brought by the traditional EKF (extended Kalman filter), UKF (unscented Kalman filter), and PF (particle filter) schemes in approximate treatment to nonlinear and non-Gaussian state model and measurement model. The numerical simulations demonstrate the feasibility and higher accuracy of the UPF navigation scheme.

  9. Modern Celestial Mechanics: From Theory to Applications

    Science.gov (United States)

    Celletti, A.; Ferraz-Mello, S.; Henrard, J.

    2002-10-01

    This book is intended to diffuse original research results interesting to people working in Celestial Mechanics in both theory and applications. Theoretical investigators will find several results on Hamiltonian Dynamics, Periodic Orbits, Chaos Diagnostic and Perturbations Theory. Applications cover several directions of research starting with those related to space exploration (mission design and space research) to those related to astronomy (extrasolar planets, asteroids, Near Earth asteroids). Since this book carries original results, it is unique and complements similar books and journals. Some of the subjects have great media appeal: the risk of impact of space debris on the Space Station, the possibility of fly-by missions to asteroids approaching dangerously to our planet, the study of the orbits of these objects, etc. Appealing for a large audience among scientists are the subjects related to Chaos and Order as well as those centered on the study of the dynamics of exoplanets (extrasolar planets). The appeal of the more theoretical papers lies in the fact that they make a tour on the state-of-the-art of several classical problems. Link: http://www.wkap.nl/prod/b/1-4020-0762-0

  10. Magnetic information calibrates celestial cues during migration.

    Science.gov (United States)

    Sandberg; Bäckman; Moore; Lõhmus

    2000-10-01

    Migratory birds use celestial and geomagnetic directional information to orient on their way between breeding and wintering areas. Cue-conflict experiments involving these two orientation cue systems have shown that directional information can be transferred from one system to the other by calibration. We designed experiments with four species of North American songbirds to: (1) examine whether these species calibrate orientation information from one system to the other; and (2) determine whether there are species-specific differences in calibration. Migratory orientation was recorded with two different techniques, cage tests and free-flight release tests, during autumn migration. Cage tests at dusk in the local geomagnetic field revealed species-specific differences: red-eyed vireo, Vireo olivaceus, and northern waterthrush, Seiurus noveboracensis, selected seasonally appropriate southerly directions whereas indigo bunting, Passerina cyanea, and grey catbird, Dumetella carolinensis, oriented towards the sunset direction. When tested in deflected magnetic fields, vireos and waterthrushes responded by shifting their orientation according to the deflection of the magnetic field, but buntings and catbirds failed to show any response to the treatment. In release tests, all four species showed that they had recalibrated their star compass on the basis of the magnetic field they had just experienced in the cage tests. Since release tests were done in the local geomagnetic field it seems clear that once the migratory direction is determined, most likely during the twilight period, the birds use their recalibrated star compass for orientation at departure. Copyright 2000 The Association for the Study of Animal Behaviour.

  11. Celestial shadows eclipses, transits, and occultations

    CERN Document Server

    Westfall, John

    2015-01-01

    Much of what is known about the universe comes from the study of celestial shadows—eclipses, transits, and occultations.  The most dramatic are total eclipses of the Sun, which constitute one of the most dramatic and awe-inspiring events of nature.  Though once a source of consternation or dread, solar eclipses now lead thousands of amateur astronomers and eclipse-chasers to travel to remote points on the globe to savor their beauty and the adrenaline-rush of experiencing totality, and were long the only source of information about the hauntingly beautiful chromosphere and corona of the Sun.   Long before Columbus, the curved shadow of the Earth on the Moon during a lunar eclipse revealed that we inhabit a round world. The rare and wonderful transits of Venus, which occur as it passes between the Earth and the Sun, inspired eighteenth century expeditions to measure the distance from the Earth to the Sun, while the recent transits of 2004 and 2012 were the most widely observed ever--and still produced re...

  12. The stratification of regolith on celestial objects

    CERN Document Server

    Schräpler, Rainer; von Borstel, Ingo; Güttler, Carsten

    2015-01-01

    All atmosphere-less planetary bodies are covered with a dust layer, the so-called regolith, which determines the optical, mechanical and thermal properties of their surface. These properties depend on the regolith material, the size distribution of the particles it consists of, and the porosity to which these particles are packed. We performed experiments in parabolic flights to determine the gravity dependency of the packing density of regolith for solid-particle sizes of 60 $\\mu$m and 1 mm as well as for 100-250 $\\mu$m-sized agglomerates of 1.5 $\\mu$m-sized solid grains. We utilized g-levels between 0.7 m s$^{-2}$ and 18 m s$^{-2}$ and completed our measurements with experiments under normal gravity conditions. Based on previous experimental and theoretical literature and supported by our new experiments, we developed an analytical model to calculate the regolith stratification of celestial rocky and icy bodies and estimated the mechanical yields of the regolith under the weight of an astronaut and a spacec...

  13. Industrial Scale Production of Celestial Body Simulants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The technical objectives of this program are to develop a cost-effective process to deliver Celestial body simulants for the foreseeable future. Specifically, the...

  14. A Review of Celestial Burying Ground in Tibet

    Institute of Scientific and Technical Information of China (English)

    YUQIAN

    2005-01-01

    Celestial burying ground ,also called “Mandala”,is where life leaves and comes.A huge piece of stone hidden in high mountains is surrounded by burning plants that give up smoke going up into the air.

  15. Frontiers in Relativistic Celestial Mechanics, Vol. 2, Applications and Experiments

    Science.gov (United States)

    Kopeikin, Sergei

    2014-08-01

    Relativistic celestial mechanics - investigating the motion celestial bodies under the influence of general relativity - is a major tool of modern experimental gravitational physics. With a wide range of prominent authors from the field, this two-volume series consists of reviews on a multitude of advanced topics in the area of relativistic celestial mechanics - starting from more classical topics such as the regime of asymptotically-flat spacetime, light propagation and celestial ephemerides, but also including its role in cosmology and alternative theories of gravity as well as modern experiments in this area. This second volume of a two-volume series covers applications of the theory as well as experimental verifications. From tools to determine light travel times in curved space-time to laser ranging between earth and moon and between satellites, and impacts on the definition of time scales and clock comparison techniques, a variety of effects is discussed. On the occasion of his 80-th birthday, these two volumes honor V. A. Brumberg - one of the pioneers in modern relativistic celestial mechanics. Contributions include: J. Simon, A. Fienga: Victor Brumberg and the French school of analytical celestial mechanics T. Fukushima: Elliptic functions and elliptic integrals for celestial mechanics and dynamical astronomy P. Teyssandier: New tools for determining the light travel time in static, spherically symmetric spacetimes beyond the order G2 J. Müller, L. Biskupek, F. Hofmann and E. Mai: Lunar laser ranging and relativity N. Wex: Testing relativistic celestial mechanics with radio pulsars I. Ciufolini et al.: Dragging of inertial frames, fundamental physics, and satellite laser ranging G. Petit, P. Wolf, P. Delva: Atomic time, clocks, and clock comparisons in relativistic spacetime: a review

  16. AUTOMATIC NAVIGATION.

    Science.gov (United States)

    NAVIGATION, REPORTS), (*CONTROL SYSTEMS, *INFORMATION THEORY), ABSTRACTS, OPTIMIZATION, DYNAMIC PROGRAMMING, GAME THEORY, NONLINEAR SYSTEMS, CORRELATION TECHNIQUES, FOURIER ANALYSIS, INTEGRAL TRANSFORMS, DEMODULATION, NAVIGATION CHARTS, PATTERN RECOGNITION, DISTRIBUTION THEORY , TIME SHARING, GRAPHICS, DIGITAL COMPUTERS, FEEDBACK, STABILITY

  17. Frontiers in Relativistic Celestial Mechanics, Vol. 1. Theory

    Science.gov (United States)

    Kopeikin, Sergei

    2014-10-01

    Relativistic celestial mechanics - investigating the motion celestial bodies under the influence of general relativity - is a major tool of modern experimental gravitational physics. With a wide range of prominent authors from the field, this two-volume series consists of reviews on a multitude of advanced topics in the area of relativistic celestial mechanics - starting from more classical topics such as the regime of asymptotically-flat spacetime, light propagation and celestial ephemerides, but also including its role in cosmology and alternative theories of gravity as well as modern experiments in this area. This first volume of a two-volume series is concerned with theoretical foundations such as post-Newtonian solutions to the two-body problem, light propagation through time-dependent gravitational fields, as well as cosmological effects on the movement of bodies in the solar systems. On the occasion of his 80-th birthday, these two volumes honor V. A. Brumberg - one of the pioneers in modern relativistic celestial mechanics. Contributions include: M. Soffel: On the DSX-framework T. Damour: The general relativistic two body problem G. Schaefer: Hamiltonian dynamics of spinning compact binaries through high post-Newtonian approximations A. Petrov and S. Kopeikin: Post-Newtonian approximations in cosmology T. Futamase: On the backreaction problem in cosmology Y. Xie and S. Kopeikin: Covariant theory of the post-Newtonian equations of motion of extended bodies S. Kopeikin and P. Korobkov: General relativistic theory of light propagation in multipolar gravitational fields

  18. Dynamical Configurations of Celestial Systems Comprised of Multiple Irregular Bodies

    CERN Document Server

    Jiang, Yu; Baoyin, Hexi; Li, Junfeng

    2016-01-01

    This manuscript considers the main features of the nonlinear dynamics of multiple irregular celestial body systems. The gravitational potential, static electric potential, and magnetic potential are considered. Based on the three established potentials, we show that three conservative values exist for this system, including a Jacobi integral. The equilibrium conditions for the system are derived and their stability analyzed. The equilibrium conditions of a celestial system comprised of n irregular bodies are reduced to 12n minus 9 equations. The dynamical results are applied to simulate the motion of multiple-asteroid systems. The simulation is useful for the study of the stability of multiple irregular celestial body systems and for the design of spacecraft orbits to triple asteroid systems discovered in the solar system. The dynamical configurations of the five triple-asteroid systems 45 Eugenia, 87 Sylvia, 93 Minerva, 216 Kleopatra, and 136617 1994CC, and the six-body system 134340 Pluto are calculated and...

  19. Pulsar Navigation in the Solar System

    CERN Document Server

    Dong, Jiang

    2008-01-01

    The X-ray Pulsar-based Autonomous Navigation(XNAV) were recently tested which use the Crab pulsar (PSR B0531+21) in the USA Experiment on flown by the Navy on the Air Force Advanced Research and Global Observation Satellite (ARGOS) under the Space Test Program. It provide the way that the spacecraft could autonomously determine its position with respect to an inertial origin. Now I analysis the sensitivity of the exist instrument and the signal process to use radio pulsar navigation and discuss the integrated navigation use pulsar,then give the different navigation mission analysis and design process basically which include the space, the airborne, the ship and the land of the planet or the lunar.So the pulsar navigation can give the continuous position in deep spaces, that means we can freedom fly successfully in the solar system use celestial navigation that include pulsar and traditional star sensor.It also can less or abolish the depend of Global Navigation Satellite System which include GPS, GRONSS, Gali...

  20. Project Vesta: A Laboratory Exercise on the Measurement of Celestial Coordinates

    Science.gov (United States)

    Laird, David E.

    1974-01-01

    Described is an activity that was developed to measure celestial coordinates. Pictures were taken of the asteroid Vesta, coordinates for reference stars determined, and then celestial coordinates of Vesta were determined with assistance of a computer. (RH)

  1. Stereotaxy, navigation and the temporal concatenation.

    Science.gov (United States)

    Apuzzo, M L; Chen, J C

    1999-01-01

    Nautical and cerebral navigation share similar elements of functional need and similar developmental pathways. The need for orientation necessitates the development of appropriate concepts, and such concepts are dependent on technology for practical realization. Occasionally, a concept precedes technology in time and requires periods of delay for appropriate development. A temporal concatenation exists where time allows the additive as need, concept and technology ultimately provide an endpoint of elegant solution. Nautical navigation has proceeded through periods of dead reckoning and celestial navigation to satellite orientation with associated refinements of instrumentation and charts for guidance. Cerebral navigation has progressed from craniometric orientation and burr hole mounted guidance systems to simple rectolinear and arc-centered devices based on radiographs to guidance by complex anatomical and functional maps provided as an amalgam of modern imaging modes. These maps are now augmented by complex frame and frameless systems which allow not only precise orientation, but also point and volumetric action. These complex technical modalities required and developed in part from elements of maritime navigation that have been translated to cerebral navigation in a temporal concatenation.

  2. Ecodesign Navigator

    DEFF Research Database (Denmark)

    Simon, M; Evans, S.; McAloone, Timothy Charles;

    The Ecodesign Navigator is the product of a three-year research project called DEEDS - DEsign for Environment Decision Support. The initial partners were Manchester Metropolitan University, Cranfield University, Engineering 6 Physical Sciences Resaech Council, Electrolux, ICL, and the Industry...

  3. Schroedinger Equation and the Quantization of Celestial Systems

    Directory of Open Access Journals (Sweden)

    Smarandache F.

    2006-04-01

    Full Text Available In the present article, we argue that it is possible to generalize Schroedinger equation to describe quantization of celestial systems. While this hypothesis has been described by some authors, including Nottale, here we argue that such a macroquantization was formed by topological superfluid vortice. We also provide derivation of Schroedinger equation from Gross-Pitaevskii-Ginzburg equation, which supports this superfluid dynamics interpretation.

  4. The IAA Cosmic Study 'Protecting the Environment of Celestial Bodies'

    Science.gov (United States)

    Rettberg, Petra; Hofmann, Mahulena; Williamson, Mark

    The study group tasked with producing this International Academy of Astronautics (IAA) `Cosmic Study' on Protecting the Environment of Celestial Bodies was formed under the aus-pices of IAA Commission V (Space Policy, Law Economy). The members of the international, multidisciplinary team assembled to undertake the Study accept, as a premise, the Planetary Protection Policy guidelines developed by COSPAR, which differentiate the degree of protec-tion according to the type of space activity and the celestial body under investigation (such that fly-by missions have less stringent requirements than lander missions, while Mars is `better protected' than the Moon). However, this Study goes deliberately beyond the interpretation of `Planetary Protection' as a set of methods for protecting the planets from biological con-tamination and extends consideration to the geophysical, industrial and cultural realms. The Study concludes that, from the perspective of current and future activities in outer space, present measures aimed at protecting the space environment are insufficient. Deficiencies in-clude a lack of suitable in-situ methods of chemical and biological detection and the absence of a systematic record of radioactive contaminants. Other issues identified by the Study include an insufficient legal framework, a shortage of effective economic tools and a lack of political will to address these concerns. It is expected that new detection methods under development, and the resultant increase in microbiological knowledge of the planetary surfaces, will lead to changes in the COSPAR planetary protection guidelines and bioburden limits. It is important, however, that any new approaches should not hamper future exploration and exploitation of celestial bodies more than absolutely necessary. The Study addresses the need to find a balance between protection and freedom of action. From a legal perspective, the Study concludes that a general consensus on protection of the

  5. Autonomous Spacecraft Navigation Based on Pulsar Timing Information

    CERN Document Server

    Bernhardt, Mike Georg; Prinz, Tobias; Breithuth, Ferdinand Maximilian; Walter, Ulrich

    2011-01-01

    We discuss the possibility of an autonomous navigation system for spacecraft that is based on pulsar timing data. Pulsars are rapidly rotating neutron stars that are observable as variable celestial sources of electromagnetic radiation. Their periodic signals have timing stabilities comparable to atomic clocks and provide characteristic temporal signatures that can be used as natural navigation beacons, quite similar to the use of GPS satellites for navigation on Earth. By comparing pulse arrival times measured on-board the spacecraft with predicted pulse arrivals at some reference location, the spacecraft position can be determined autonomously with accuracies on the order of 5 kilometres. For a spacecraft at a distance of 10 astronomical units from Earth (e.g., Earth-Saturn), this means an improvement by a factor of 8 compared to conventional methods. Therefore this new technology is an alternative to standard navigation based on radio tracking by ground stations, without the disadvantages of uncertainty in...

  6. 5th Austrian Hungarian workshop on celestial mechanics

    Science.gov (United States)

    Süli, Áron

    2011-06-01

    The 5th Hungarian-Austrian Workshop on Celestial Mechanics took place from 9th until the 10th of April 2010 in Vienna, Austria. The workshop was held in the Institute for Astronomy of Vienna University. From the Eötvös University and from the host institute experts and PhD students gathered together to discuss the challenges and new results of the actual problems of celestial mechanics. The workshop was held in the meeting room at the Sternwarte of the Vienna University located in a magnificent park in the heart of Vienna. Following the themes of the four previous events the focus for this workshop ranged from the Trojan problem, dynamics in binary star systems and exoplanetray systems. We were pleased to acknowledge the support of the host university. The talks were characterized by a large spectrum, which is typical of the workshops on celestial mechanics. Several talks discussed different aspects of the trojan problem, such as the three Trojan Problem, dynamics of trojan-like planets in binary stars, the frequencies of their motion around the triangular lagrangian points, etc. Several speakers focused on the formation of planetary systems and on the field of exoplanetary systems, like exoplanetary systems in higher order mean motion resonances, formation of planets in binary systems, stability of exomoons etc. Some of the presentation used sophisticated mathematical tools in order to understand mean motion resonances, the Sitnikov problem applying the KAM and the Nekhoroshev theorem. The theme of a number of talks was the motion of Solar System bodies: dynamics of the newly discovered moons of Pluto and of near-Earth asteroids. General problems were also addressed, among others chaos in Hamiltonian systems, adaptive Lie-integration method and iterative solution approximation to the generalised Sitnikov problem.

  7. TRIP: General computer algebra system for celestial mechanics

    Science.gov (United States)

    Laskar, J.; Gastineau, M.

    2012-10-01

    TRIP is an interactive computer algebra system that is devoted to perturbation series computations, and specially adapted to celestial mechanics. Its development started in 1988, as an upgrade of the special purpose FORTRAN routines elaborated by J. Laskar for the demonstration of the chaotic behavior of the Solar System. TRIP is a mature and efficient tool for handling multivariate generalized power series, and embeds two kernels, a symbolic and a numerical kernel. This numerical kernel communicates with Gnuplot or Grace to plot the graphics and allows one to plot the numerical evaluation of symbolic objects.

  8. Kepler-16 Circumbinary System Validates Quantum Celestial Mechanics

    Directory of Open Access Journals (Sweden)

    Potter F.

    2012-01-01

    Full Text Available We report the application of quantum celestial mechanics (QCM to the Kepler-16 cir- cumbinary system which has a single planet orbiting binary stars with the important system parameters known to within one percent. Other gravitationally bound systems such as the Solar System of planets and the Jovian satellite systems have large uncertain- ties in their total angular momentum. Therefore, Kepler-16 allows us for the first time to determine whether the QCM predicted angular momentum per mass quantization is valid.

  9. The Power of Stars How Celestial Observations Have Shaped Civilization

    CERN Document Server

    Penprase, Bryan E

    2011-01-01

    What are some of the connections that bind us to the stars? How have these connections been established? And how have people all around the world and throughout time reacted to the night sky, the sun and moon, in their poetry, mythology, rituals, and temples? This book explores the influence of the sky on both ancient and modern civilization, by providing a clear overview of the many ways in which humans have used the stars as an ordering principle in their cultures, and which today still inspire us intellectually, emotionally, and spiritually. The book explores constellation lore from around the world, celestial alignments of monuments and temples, both from ancient and modern civilizations, and the role the sky has played in the cultures of the Greek, Egyptian, Babylonian, Native American, Chinese, Mayan, Aztec, and Inca. Models of the universe from each of these cultures are described clearly, and each culture’s explanation of the stars, planets, and other celestial objects are described. The roots of as...

  10. On the abundance of deuterium in celestial objects

    Science.gov (United States)

    Lundin, Rickard; Kero, Johan; Liszka, Ludwik

    2016-04-01

    The deuterium hydrogen ratio (D/H) is the subject of conflicting ideas about the origin of water on the Earth. The present D/H ratio in the Earth oceans (≈1.5x10-4) is substantially lower than most, if not all potential cosmic sources. Furthermore, other celestial bodies, including interstellar space, display a fairly wide range of D/H ratios superseding the terrestrial one. Escape processes may in part explain higher D/H ratios on Mars and Venus, but cannot explain the Earth's low ratio compared to that of the potential sources (e.g. comets and meteors), unless a deuterium "removal" process can be inferred that reduces the D/H ratio. Alternatively, the D/H ratio in the Earth's ocean represents a time capsule of a yet to be identified cosmic source. It is here hypothesized that the former is the cause, a "removal" of deuterium in matter (carbohydrates, water etc.) having high (pristine) D/H ratios. By "removal" is here meant an isotope transmutation, i.e. deuterium is transmuted to hydrogen plus a thermal neutron, a process requiring >2.25 MeV (≈3.6·10-13 J). However, once released a thermal neutron will eventually fuse with another heavier element by thermal neutron capture, a process that may lead to energy in excess of the spallation energy. The energy gain differs for different isotopes, but if exceeding unity it will induce more heat/power than the input power, maintaining power production over time. A gain less than unity will still result in deuterium removal, but also isotope transmutation, and/or element transmutation via β± decay. This report gives a theoretical background for the plasma forcing that can lead to thermal neutron spallation, a process that changes/decrease the D/H ratio in celestial objects. The applicability of the theory will be tested on celestial objects subjected to strong dynamic, and electromagnetic forcing, by the Sun or during the entry of high-speed objects into the Earth's atmosphere.

  11. The ancient Armenian calendars' connection with the celestial bodies

    Science.gov (United States)

    Broutian, G. H.

    2015-07-01

    The two oldest Armenian calendars - the Haykian and Protohaykian calendars were connected with observations of celestial bodies. Particularly since 2341 B.C. the heliacal rising of the first star of Orion was used to determine the day of the main holiday - Nawasard. Before that the observations of the same star were used in Protohaykian calendar to determine both the beginning and the end of the year. The year was determined as the duration of visibility of the star Betelgeuse. The year started with the heliacal rising of this star and ended with its heliacal setting. The remaining duration was considered to be out of the year. There are also evidences in Armenian medieval literary sources concerning the observations of heliacal rising and setting of Pleiades. An attempt was made to substantiate that the large symbol carved on the rock platform of the small hill in Metzamor also concerns to the Pleiades and shows the direction of heliacal rising of Pleiades.

  12. Incontri celesti, vita del padre Clavio in cinque atti

    CERN Document Server

    Sigismondi, Costantino

    2011-01-01

    The year 2012 will be the fourth centennial year of the Jesuit Christopher Clavius (1535-1612), known as the Euclid of XVI century and the collaborator of the Pope Gregory XIII for the calendar reformation. In the occasion of the year of astronomy I wrote a short theatre pi\\`ece "Celestial encounters" dedicated to the life of Ft. Clavius. He observed two total eclipses from centreline in 1560 in Coimbra and in 1567 in Rome, a fact which is remarkable even for contemporary astronomers. The story is developed around those trips: scientific and religious motivations are put in evidence with historical and fantasy, but realistic, facts. An interregional project between Switzerland and Italy, dedicated to the development of high resolution CMOS camera for astronomy and medical sciences has been entitled to Clavius and will produce high resolution measurements of solar diameter.

  13. An approach to Mel'nikov theory in celestial mechanics

    CERN Document Server

    Cicogna, G

    1999-01-01

    Using a completely analytic procedure - based on a suitable extension of a classical method - we discuss an approach to the Poincaré-Mel'nikov theory, which can be conveniently applied also to the case of non-hyperbolic critical points, and even if the critical point is located at the infinity. In this paper, we concentrate our attention on the latter case, and precisely on problems described by Kepler-like potentials in one or two degrees of freedom, in the presence of general time-dependent perturbations. We show that the appearance of chaos (possibly including Arnol'd diffusion) can be proved quite easily and in a direct way, without resorting to singular coordinate transformations, such as the McGehee or blowing-up transformations. Natural examples are provided by the classical Gyldén problem, originally proposed in celestial mechanics, but also of interest in different fields, and by the general 3-body problem in classical mechanics.

  14. Navigation Lights - USACE IENC

    Data.gov (United States)

    Department of Homeland Security — These inland electronic Navigational charts (IENCs) were developed from available data used in maintenance of Navigation channels. Users of these IENCs should be...

  15. Vision and visual navigation in nocturnal insects.

    Science.gov (United States)

    Warrant, Eric; Dacke, Marie

    2011-01-01

    With their highly sensitive visual systems, nocturnal insects have evolved a remarkable capacity to discriminate colors, orient themselves using faint celestial cues, fly unimpeded through a complicated habitat, and navigate to and from a nest using learned visual landmarks. Even though the compound eyes of nocturnal insects are significantly more sensitive to light than those of their closely related diurnal relatives, their photoreceptors absorb photons at very low rates in dim light, even during demanding nocturnal visual tasks. To explain this apparent paradox, it is hypothesized that the necessary bridge between retinal signaling and visual behavior is a neural strategy of spatial and temporal summation at a higher level in the visual system. Exactly where in the visual system this summation takes place, and the nature of the neural circuitry that is involved, is currently unknown but provides a promising avenue for future research.

  16. Numeric calculation of celestial bodies with spreadsheet analysis

    Science.gov (United States)

    Koch, Alexander

    2016-04-01

    The motion of the planets and moons in our solar system can easily be calculated for any time by the Kepler laws of planetary motion. The Kepler laws are a special case of the gravitational law of Newton, especially if you consider more than two celestial bodies. Therefore it is more basic to calculate the motion by using the gravitational law. But the problem is, that by gravitational law it is not possible to calculate the state of motion with only one step of calculation. The motion has to be numerical calculated for many time intervalls. For this reason, spreadsheet analysis is helpful for students. Skills in programmes like Excel, Calc or Gnumeric are important in professional life and can easily be learnt by students. These programmes can help to calculate the complex motions with many intervalls. The more intervalls are used, the more exact are the calculated orbits. The sutdents will first get a quick course in Excel. After that they calculate with instructions the 2-D-coordinates of the orbits of Moon and Mars. Step by step the students are coding the formulae for calculating physical parameters like coordinates, force, acceleration and velocity. The project is limited to 4 weeks or 8 lessons. So the calcualtion will only include the calculation of one body around the central mass like Earth or Sun. The three-body problem can only be shortly discussed at the end of the project.

  17. Celestial delights the best astronomical events through 2020

    CERN Document Server

    Reddy, Francis

    2012-01-01

    Celestial Delights is the essential 'TV Guide' for the sky. Through extensive graphics integrated with an eight-year-long calendar of sky events, it provides a look at "don't miss" sky events, mostly for naked-eye and binocular observing. It is organized by ease of observation – lunar phases and the brighter planets come first, with solar eclipses, the aurora, and comets coming later. This third edition also includes a hefty dose of sky lore, astronomical history, and clear overviews of current science. It provides a handy reference to upcoming naked-eye events, with information broken out in clear and simple diagrams and tables that are cross-referenced against a detailed almanac for each year covered. This book puts a variety of information all in one place, presents it in a friendly way that does not require prior in-depth astronomical knowledge, and provides the context and historical background for understanding events that astronomy software or web sites lack.

  18. The periodic dynamics of the irregular heterogeneous celestial bodies

    Science.gov (United States)

    Lan, Lei; Yang, Mo; Baoyin, Hexi; Li, Junfeng

    2017-02-01

    In this paper, we develop a methodology to study the periodic dynamics of irregular heterogeneous celestial bodies. Heterogeneous bodies are not scarce in space. It has been found that bodies, such as 4 Vesta, 624 Hektor, 87 Sylvia, 16 Psyche and 25143 Itokawa, may all have varied internal structures. They can be divided into large-scale and small-scale cases. The varied internal structures of large-scale bodies always result from gradient pressure inside, which leads to compactness differences of the inner material. However, the heterogeneity of a small-scale body is always reflected by the different densities of different areas, which may originate from collision formation from multiple objects. We propose a modeling procedure for the heterogeneous bodies derived from the conventional polyhedral method and then compare its dynamical characteristics with those of the homogeneous case. It is found that zero-velocity curves, positions of equilibrium points, types of bifurcations in the continuation of the orbital family and the stabilities of periodic orbits near the heterogeneous body are different from those in the homogeneous case. The suborbicular orbits near the equatorial plane are potential parking orbits for a future mission, so we discuss the switching of the orbital stability of the family because it has fundamental significance to orbit maintenance and operations around actual asteroids.

  19. Inertial Navigation Sensors

    Science.gov (United States)

    2010-03-01

    Capteurs de navigation a faible cout et technologie d’integration) RTO-EN-SET-116(2010) 14. ABSTRACT For many navigation applications , improved...ABSTRACT For many navigation applications , improved accuracy/performance is not necessarily the most important issue, but meeting performance at...reduced cost and size is. In particular, small navigation sensor size allows the introduction of guidance, navigation, and control into applications

  20. Apollo Onboard Navigation Techniques

    Science.gov (United States)

    Interbartolo, Michael

    2009-01-01

    This viewgraph presentation reviews basic navigation concepts, describes coordinate systems and identifies attitude determination techniques including Primary Guidance, Navigation and Control System (PGNCS) IMU management and Command and Service Module Stabilization and Control System/Lunar Module (LM) Abort Guidance System (AGS) attitude management. The presentation also identifies state vector determination techniques, including PGNCS coasting flight navigation, PGNCS powered flight navigation and LM AGS navigation.

  1. Kilohoku Ho`okele Wa`a : Astronomy of the Hawaiian Navigators

    Science.gov (United States)

    Slater, Stephanie; Slater, Timothy F.; Baybayan, Kalepa C.

    2016-01-01

    This poster provides an introduction to the astronomy of the Hawaiian wayfinders, Kilohoku Ho`okele Wa`a. Rooted in a legacy of navigation across the Polynesian triangle, wayfinding astronomy has been part of a suite of skills that allows navigators to deliberately hop between the small islands of the Pacific, for thousands of years. Forty years ago, in one manifestation of the Hawaiian Renaissance, our teachers demonstrated that ancient Hawaiians were capable of traversing the wide Pacific to settle and trade on islands separated by thousands of miles. Today those same mentors train a new generation of navigators, making Hawaiian voyaging a living, evolving, sustainable endeavor. This poster presents two components of astronomical knowledge that all crewmen, but particularly those in training to become navigators, learn early in their training. Na Ohana Hoku, the Hawaiian Star Families constitute the basic units of the Hawaiian sky. In contrast to the Western system of 88 constellations, Na Ohana Hoku divides the sky into four sections that each run from the northern to the southern poles. This configuration reduces cognitive load, allowing the navigator to preserve working memory for other complex tasks. In addition, these configurations of stars support the navigator in finding and generatively using hundreds of individual, and navigationally important pairs of stars. The Hawaiian Star Compass divides the celestial sphere into a directional system that uses 32 rather than 8 cardinal points. Within the tropics, the rising and setting of celestial objects are consistent within the Hawaiian Star Compass, providing for extremely reliable direction finding. Together, Na Ohana Hoku and the Hawaiian Star Compass provide the tropical navigator with astronomical assistance that is not available to, and would have been unknown to Western navigators trained at higher latitudes.

  2. SINS/CNS Nonlinear Integrated Navigation Algorithm for Hypersonic Vehicle

    Directory of Open Access Journals (Sweden)

    Yong-jun Yu

    2015-01-01

    Full Text Available Celestial Navigation System (CNS has characteristics of accurate orientation and strong autonomy and has been widely used in Hypersonic Vehicle. Since the CNS location and orientation mainly depend upon the inertial reference that contains errors caused by gyro drifts and other error factors, traditional Strap-down Inertial Navigation System (SINS/CNS positioning algorithm setting the position error between SINS and CNS as measurement is not effective. The model of altitude azimuth, platform error angles, and horizontal position is designed, and the SINS/CNS tightly integrated algorithm is designed, in which CNS altitude azimuth is set as measurement information. GPF (Gaussian particle filter is introduced to solve the problem of nonlinear filtering. The results of simulation show that the precision of SINS/CNS algorithm which reaches 130 m using three stars is improved effectively.

  3. Dawes Review 5: Australian Aboriginal Astronomy and Navigation

    CERN Document Server

    Norris, Ray P

    2016-01-01

    The traditional cultures of Aboriginal Australians include a significant astronomical component, perpetuated through oral tradition, ceremony, and art. This astronomical knowledge includes a deep understanding of the motion of objects in the sky, which was used for practical purposes such as constructing calendars and for navigation. There is also evidence that traditional Aboriginal Australians made careful records and measurements of cyclical phenomena, recorded unexpected phenomena such as eclipses and meteorite impacts, and could determine the cardinal points to an accuracy of a few degrees. Putative explanations of celestial phenomena appear throughout the oral record, suggesting traditional Aborig- inal Australians sought to understand the natural world around them, in the same way as modern scientists, but within their own cultural context. There is also a growing body of evidence for sophisticated navigational skills, including the use of astronomically based songlines. Songlines are effectively oral ...

  4. Optical Navigation System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for a flexible navigation system for deep space operations that does not require GPS measurements. The navigation solution is computed using an...

  5. A novel interplanetary optical navigation algorithm based on Earth-Moon group photos by Chang'e-5T1 probe

    Science.gov (United States)

    Bu, Yanlong; Zhang, Qiang; Ding, Chibiao; Tang, Geshi; Wang, Hang; Qiu, Rujin; Liang, Libo; Yin, Hejun

    2017-02-01

    This paper presents an interplanetary optical navigation algorithm based on two spherical celestial bodies. The remarkable characteristic of the method is that key navigation parameters can be estimated depending entirely on known sizes and ephemerides of two celestial bodies, especially positioning is realized through a single image and does not rely on traditional terrestrial radio tracking any more. Actual Earth-Moon group photos captured by China's Chang'e-5T1 probe were used to verify the effectiveness of the algorithm. From 430,000 km away from the Earth, the camera pointing accuracy reaches 0.01° (one sigma) and the inertial positioning error is less than 200 km, respectively; meanwhile, the cost of the ground control and human resources are greatly reduced. The algorithm is flexible, easy to implement, and can provide reference to interplanetary autonomous navigation in the solar system.

  6. Radar and electronic navigation

    CERN Document Server

    Sonnenberg, G J

    2013-01-01

    Radar and Electronic Navigation, Sixth Edition discusses radar in marine navigation, underwater navigational aids, direction finding, the Decca navigator system, and the Omega system. The book also describes the Loran system for position fixing, the navy navigation satellite system, and the global positioning system (GPS). It reviews the principles, operation, presentations, specifications, and uses of radar. It also describes GPS, a real time position-fixing system in three dimensions (longitude, latitude, altitude), plus velocity information with Universal Time Coordinated (UTC). It is accur

  7. Space Shuttle navigation validation

    Science.gov (United States)

    Ragsdale, A.

    The validation of the guidance, navigation, and control system of the Space Shuttle is explained. The functions of the ascent, on-board, and entry mission phases software of the navigation system are described. The common facility testing, which evaluates the simulations to be used in the navigation validation, is examined. The standard preflight analysis of the operational modes of the navigation software and the post-flight navigation analysis are explained. The conversion of the data into a useful reference frame and the use of orbit parameters in the analysis of the data are discussed. Upon entry the data received are converted to flags, ratios, and residuals in order to evaluate performance and detect errors. Various programs developed to support navigation validation are explained. A number of events that occurred with the Space Shuttle's navigation system are described.

  8. Forecasting scenarios of collision catastrophes produced by celestial body falls

    Science.gov (United States)

    Shor, V.; Kochetova, O.; Chernetenko, Y.; Zheleznov, N.; Deryugin, V.; Zaitsev, A.

    2014-07-01

    The subject under discussion arose in the course of developing a computer program, which gives the possibility for numerical and graphical modeling of the scenarios of catastrophes caused by collisions of cosmic bodies with the Earth. It is expected that this program can be used for computer-assisted training of the personnel of units of the Ministry for Emergency Situations in the case of a situation caused by the fall of a celestial body on the Earth. Also, it is anticipated that the program can be used in real situations when a dangerous body is discovered on an orbit leading to an imminent collision with the Earth. From the scientific point of view, both variants of use require solving of analogous tasks. In what follows, we discuss both variants. 1. The computation of the circumstances for a fall on the Earth (or approach within short distance) of a real body begins with the determination of its orbit from the observations available using the least-squares method. The mean square error of the representation of the observations on the base of the initial values of the coordinates and the velocities is computed, as well as their covariance matrix. Then, the trajectory of the body's motion is followed by numerical integration starting from the osculating epoch to the collision with the Earth or to its flyby. The computer program takes into account the various cases: at the initial moment, the body can move away from or approach the Earth, it can be outside the sphere of action or inside it. At the moment, when the body enters the sphere of action, the coordinates of the center of the dispersion ellipse on the target plane are computed as well as the dimensions of its axes. Using these data, the probability of collision with the Earth is calculated. Then, the point of penetration of the body into the Earth's atmosphere at a given height above the level of the Earth geoid is determined. In case the body is passing by the Earth, the minimum distance of the body from

  9. Indoor wayfinding and navigation

    CERN Document Server

    2015-01-01

    Due to the widespread use of navigation systems for wayfinding and navigation in the outdoors, researchers have devoted their efforts in recent years to designing navigation systems that can be used indoors. This book is a comprehensive guide to designing and building indoor wayfinding and navigation systems. It covers all types of feasible sensors (for example, Wi-Fi, A-GPS), discussing the level of accuracy, the types of map data needed, the data sources, and the techniques for providing routes and directions within structures.

  10. Illustrating the phaenomena celestial cartography in antiquity and the Middle Ages

    CERN Document Server

    Dekker, Elly

    2013-01-01

    In this volume all extant celestial maps and globes made before 1500 are described and analysed. It also discusses the astronomical sources involved in making these artefacts in antiquity, the Middle Ages, the Islamic world and the European Renaissance before 1500.

  11. The Gravitational Effects of a Celestial Body with Magnetic Charge and Moment

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The gravitational effects (precession of charge-less particles and deflection of light) in the gravitational field of a celestial body with magnetic charge and moment (CM)are investigated. We found that the magnetic charge always weakens the pure Schwarzschild effects, while the magnetic dipole moment deforms the effects in a more complicated way.

  12. Restricted Navigation Areas - USACE IENC

    Data.gov (United States)

    Department of Homeland Security — These inland electronic Navigational charts (IENCs) were developed from available data used in maintenance of Navigation channels. Users of these IENCs should be...

  13. Processing Images of Craters for Spacecraft Navigation

    Science.gov (United States)

    Cheng, Yang; Johnson, Andrew E.; Matthies, Larry H.

    2009-01-01

    A crater-detection algorithm has been conceived to enable automation of what, heretofore, have been manual processes for utilizing images of craters on a celestial body as landmarks for navigating a spacecraft flying near or landing on that body. The images are acquired by an electronic camera aboard the spacecraft, then digitized, then processed by the algorithm, which consists mainly of the following steps: 1. Edges in an image detected and placed in a database. 2. Crater rim edges are selected from the edge database. 3. Edges that belong to the same crater are grouped together. 4. An ellipse is fitted to each group of crater edges. 5. Ellipses are refined directly in the image domain to reduce errors introduced in the detection of edges and fitting of ellipses. 6. The quality of each detected crater is evaluated. It is planned to utilize this algorithm as the basis of a computer program for automated, real-time, onboard processing of crater-image data. Experimental studies have led to the conclusion that this algorithm is capable of a detection rate >93 percent, a false-alarm rate <5 percent, a geometric error <0.5 pixel, and a position error <0.3 pixel.

  14. Dawes Review 5: Australian Aboriginal Astronomy and Navigation

    Science.gov (United States)

    Norris, Ray P.

    2016-08-01

    The traditional cultures of Aboriginal Australians include a significant astronomical component, perpetuated through oral tradition, ceremony, and art. This astronomical knowledge includes a deep understanding of the motion of objects in the sky, which was used for practical purposes such as constructing calendars and for navigation. There is also evidence that traditional Aboriginal Australians made careful records and measurements of cyclical phenomena, recorded unexpected phenomena such as eclipses and meteorite impacts, and could determine the cardinal points to an accuracy of a few degrees. Putative explanations of celestial phenomena appear throughout the oral record, suggesting traditional Aboriginal Australians sought to understand the natural world around them, in the same way as modern scientists, but within their own cultural context. There is also a growing body of evidence for sophisticated navigational skills, including the use of astronomically based songlines. Songlines are effectively oral maps of the landscape, and are an efficient way of transmitting oral navigational skills in cultures that do not have a written language. The study of Aboriginal astronomy has had an impact extending beyond mere academic curiosity, facilitating cross-cultural understanding, demonstrating the intimate links between science and culture, and helping students to engage with science.

  15. 78 FR 68861 - Certain Navigation Products, Including GPS Devices, Navigation and Display Systems, Radar Systems...

    Science.gov (United States)

    2013-11-15

    ... COMMISSION Certain Navigation Products, Including GPS Devices, Navigation and Display Systems, Radar Systems... the United States after importation of certain navigation products, including GPS devices, navigation... products, including GPS devices, navigation and display systems, radar systems, navigational aids,...

  16. The attack navigator

    DEFF Research Database (Denmark)

    Probst, Christian W.; Willemson, Jan; Pieters, Wolter

    2016-01-01

    -technical system, the attack navigator identifies routes to an attacker goal. Specific attacker properties such as skill or resources can be included through attacker profiles. This enables defenders to explore attack scenarios and the effectiveness of defense alternatives under different threat conditions....... that are caused by the strategic behaviour of adversaries. Therefore, technology-supported methods are needed to help us identify and manage these risks. In this paper, we describe the attack navigator: a graph-based approach to security risk assessment inspired by navigation systems. Based on maps of a socio...

  17. Algorithms for vehicle navigation

    OpenAIRE

    Storandt, Sabine

    2012-01-01

    Nowadays, navigation systems are integral parts of most cars. They allow the user to drive to a preselected destination on the shortest or quickest path by giving turn-by-turn directions. To fulfil this task the navigation system must be aware of the current position of the vehicle at any time, and has to compute the optimal route to the destination on that basis. Both of these subproblems have to be solved frequently, because the navigation system must react immediately if the vehicle leaves...

  18. Mobile Robot Navigation

    DEFF Research Database (Denmark)

    Andersen, Jens Christian

    2007-01-01

    Abstract Robots will soon take part in everyone’s daily life. In industrial production this has been the case for many years, but up to now the use of mobile robots has been limited to a few and isolated applications like lawn mowing, surveillance, agricultural production and military applications....... The research is now progressing towards autonomous robots which will be able to assist us in our daily life. One of the enabling technologies is navigation, and navigation is the subject of this thesis. Navigation of an autonomous robot is concerned with the ability of the robot to direct itself from...

  19. Heavenly Networks. Celestial Maps and Globes in Circulation between Artisans, Mathematicians, and Noblemen in Renaissance Europe.

    Science.gov (United States)

    Gessner, Samuel

    2015-01-01

    The aim of this paper is to examine the iconography on a set of star charts by Albrecht Dürer (1515), and celestial globes by Caspar Vopel (1536) and Christoph Schissler (1575). The iconography on these instruments is conditioned by strong traditions which include not only the imagery on globes and planispheres (star charts), but also ancient literature about the constellations. Where this iconography departs from those traditions, the change had to do with humanism in the sixteenth century. This "humanistic" dimension is interwoven with other concerns that involve both "social" and "technical" motivations. The interplay of these three dimensions illustrates how the iconography on celestial charts and globes expresses some features of the shared knowledge and shared culture between artisans, mathematicians, and nobles in Renaissance Europe.

  20. UBVRI Photometric Standard Stars Around the Celestial Equator: Updates and Additions

    CERN Document Server

    Landolt, Arlo U

    2009-01-01

    New broadband UBVRI photoelectric observations on the Johnson-Kron-Cousins photometric system have been made of 202 stars around the sky, and centered at the celestial equator. These stars constitute both an update of and additions to a previously published list of equatorial photometric standard stars. The list is capable of providing, for both celestial hemispheres, an internally consistent homogeneous broadband standard photometric system around the sky. When these new measurements are included with those previously published by Landolt (1992), the entire list of standard stars in this paper encompasses the magnitude range 8.90 < V < 16.30, and the color index range -0.35 < (B - V) < +2.30.

  1. The impact of celestial pole offset modelling on VLBI UT1 Intensive results

    CERN Document Server

    Malkin, Zinovy

    2011-01-01

    Very Long Baseline Interferometry (VLBI) Intensive sessions are scheduled to provide operational Universal Time (UT1) determinations with low latency. UT1 estimates obtained from these observations heavily depend on the model of the celestial pole motion used during data processing. However, even the most accurate precession-nutation model, IAU 2000/2006, is not accurate enough to realize the full potential of VLBI observations. To achieve the highest possible accuracy in UT1 estimates, a celestial pole offset (CPO), which is the difference between the actual and modelled precession-nutation angles, should be applied. Three CPO models are currently available for users. In this paper, these models have been tested and the differences between UT1 estimates obtained with those models are investigated. It has been shown that neglecting CPO modelling during VLBI UT1 Intensive processing causes systematic errors in UT1 series of up to 20 microarcseconds. It has been also found that using different CPO models causes...

  2. USACE Navigation Channels 2012

    Data.gov (United States)

    California Department of Resources — This dataset represents both San Francisco and Los Angeles District navigation channel lines. All San Francisco District channel lines were digitized from CAD files...

  3. OPTICAL SPECTRA OF CANDIDATE INTERNATIONAL CELESTIAL REFERENCE FRAME (ICRF) FLAT-SPECTRUM RADIO SOURCES

    Energy Technology Data Exchange (ETDEWEB)

    Titov, O.; Stanford, Laura M. [Geoscience Australia, P.O. Box 378, Canberra, ACT 2601 (Australia); Johnston, Helen M.; Hunstead, Richard W. [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Pursimo, T. [Nordic Optical Telescope, Nordic Optical Telescope Apartado 474E-38700 Santa Cruz de La Palma, Santa Cruz de Tenerife (Spain); Jauncey, David L. [CSIRO Astronomy and Space Science, ATNF and Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Maslennikov, K. [Central Astronomical Observatory at Pulkovo, Pulkovskoye Shosse, 65/1, 196140, St. Petersburg (Russian Federation); Boldycheva, A., E-mail: oleg.titov@ga.gov.au [Ioffe Physical Technical Institute, 26 Polytekhnicheskaya, St. Petersburg, 194021 (Russian Federation)

    2013-07-01

    Continuing our program of spectroscopic observations of International Celestial Reference Frame (ICRF) sources, we present redshifts for 120 quasars and radio galaxies. Data were obtained with five telescopes: the 3.58 m European Southern Observatory New Technology Telescope, the two 8.2 m Gemini telescopes, the 2.5 m Nordic Optical Telescope (NOT), and the 6.0 m Big Azimuthal Telescope of the Special Astrophysical Observatory in Russia. The targets were selected from the International VLBI Service for Geodesy and Astrometry candidate International Celestial Reference Catalog which forms part of an observational very long baseline interferometry (VLBI) program to strengthen the celestial reference frame. We obtained spectra of the potential optical counterparts of more than 150 compact flat-spectrum radio sources, and measured redshifts of 120 emission-line objects, together with 19 BL Lac objects. These identifications add significantly to the precise radio-optical frame tie to be undertaken by Gaia, due to be launched in 2013, and to the existing data available for analyzing source proper motions over the celestial sphere. We show that the distribution of redshifts for ICRF sources is consistent with the much larger sample drawn from Faint Images of the Radio Sky at Twenty cm (FIRST) and Sloan Digital Sky Survey, implying that the ultra-compact VLBI sources are not distinguished from the overall radio-loud quasar population. In addition, we obtained NOT spectra for five radio sources from the FIRST and NRAO VLA Sky Survey catalogs, selected on the basis of their red colors, which yielded three quasars with z > 4.

  4. An Overview of Major Terrestrial, Celestial, and Temporal Coordinate Systems for Target Tracking

    Science.gov (United States)

    2016-08-10

    quadrant inverse tangent in (B2) is not uniquely defined at the poles (when x “ 0 and y “ 0). However, many implementations of the four-quadrant inverse ...Harmonic Coordinates .................................... 105 APPENDIX E—Principal Axes, Precession, Nutation, and the Pole Tide...on the Celestial Sphere z ` Pole of the Ecliptic ˘ x ˆ IERS Reference Meridian « Dynamical Equinox at Epoch ˙ , P z ` IERS Reference Pole

  5. Coastal Navigation Portfolio Management

    Science.gov (United States)

    2015-02-19

    the entire navigation portfolio of projects , both inland and coastal. The Coastal Structures Management , Analysis, and Ranking Tool (CSMART) is a...FEB 2015 2. REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE Coastal Navigatoin Portfolio Management 5a. CONTRACT...CIRP.aspx Coastal Inlets Research Program Coastal Navigation Portfolio Management The Coastal Navigatoin Portfolio Management work unit

  6. 33 CFR 209.325 - Navigation lights, aids to navigation, navigation charts, and related data policy, practices and...

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Navigation lights, aids to navigation, navigation charts, and related data policy, practices and procedure. 209.325 Section 209.325 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF...

  7. Risk of Adverse Health and Performance Effects of Celestial Dust Exposure

    Science.gov (United States)

    Scully, Robert R.; Meyers, Valerie E.

    2015-01-01

    Crew members can be directly exposed to celestial dust in several ways. After crew members perform extravehicular activities (EVAs), they may introduce into the habitat dust that will have collected on spacesuits and boots. Cleaning of the suits between EVAs and changing of the Environmental Control Life Support System filters are other operations that could result in direct exposure to celestial dusts. In addition, if the spacesuits used in exploration missions abrade the skin, as current EVA suits have, then contact with these wounds would provide a source of exposure. Further, if celestial dusts gain access to a suit's interior, as was the case during the Apollo missions, the dust could serve as an additional source of abrasions or enhance suit-induced injuries. When a crew leaves the surface of a celestial body and returns to microgravity, the dust that is introduced into the return vehicle will "float," thus increasing the opportunity for ocular and respiratory injury. Because the features of the respirable fraction of lunar dusts indicate they could be toxic to humans, NASA conducted several studies utilizing lunar dust simulants and authentic lunar dust to determine the unique properties of lunar dust that affect physiology, assess the dermal and ocular irritancy of the dust, and establish a permissible exposure limit for episodic exposure to airborne lunar dust during missions that would involve no more than 6 months stay on the lunar surface. Studies, with authentic lunar soils from both highland (Apollo 16) and mare (Apollo17) regions demonstrated that the lunar soil is highly abrasive to a high fidelity model of human skin. Studies of lunar dust returned during the Apollo 14 mission from an area of the moon in which the soils were comprised of mineral constituents from both major geological regions (highlands and mares regions) demonstrated only minimal ocular irritancy, and pulmonary toxicity that was less than the highly toxic terrestrial crystalline

  8. Integrated Navigation System Design for Micro Planetary Rovers: Comparison of Absolute Heading Estimation Algorithms and Nonlinear Filtering

    Science.gov (United States)

    Ilyas, Muhammad; Hong, Beomjin; Cho, Kuk; Baeg, Seung-Ho; Park, Sangdeok

    2016-01-01

    This paper provides algorithms to fuse relative and absolute microelectromechanical systems (MEMS) navigation sensors, suitable for micro planetary rovers, to provide a more accurate estimation of navigation information, specifically, attitude and position. Planetary rovers have extremely slow speed (~1 cm/s) and lack conventional navigation sensors/systems, hence the general methods of terrestrial navigation may not be applicable to these applications. While relative attitude and position can be tracked in a way similar to those for ground robots, absolute navigation information is hard to achieve on a remote celestial body, like Moon or Mars, in contrast to terrestrial applications. In this study, two absolute attitude estimation algorithms were developed and compared for accuracy and robustness. The estimated absolute attitude was fused with the relative attitude sensors in a framework of nonlinear filters. The nonlinear Extended Kalman filter (EKF) and Unscented Kalman filter (UKF) were compared in pursuit of better accuracy and reliability in this nonlinear estimation problem, using only on-board low cost MEMS sensors. Experimental results confirmed the viability of the proposed algorithms and the sensor suite, for low cost and low weight micro planetary rovers. It is demonstrated that integrating the relative and absolute navigation MEMS sensors reduces the navigation errors to the desired level. PMID:27223293

  9. Integrated Navigation System Design for Micro Planetary Rovers: Comparison of Absolute Heading Estimation Algorithms and Nonlinear Filtering.

    Science.gov (United States)

    Ilyas, Muhammad; Hong, Beomjin; Cho, Kuk; Baeg, Seung-Ho; Park, Sangdeok

    2016-05-23

    This paper provides algorithms to fuse relative and absolute microelectromechanical systems (MEMS) navigation sensors, suitable for micro planetary rovers, to provide a more accurate estimation of navigation information, specifically, attitude and position. Planetary rovers have extremely slow speed (~1 cm/s) and lack conventional navigation sensors/systems, hence the general methods of terrestrial navigation may not be applicable to these applications. While relative attitude and position can be tracked in a way similar to those for ground robots, absolute navigation information is hard to achieve on a remote celestial body, like Moon or Mars, in contrast to terrestrial applications. In this study, two absolute attitude estimation algorithms were developed and compared for accuracy and robustness. The estimated absolute attitude was fused with the relative attitude sensors in a framework of nonlinear filters. The nonlinear Extended Kalman filter (EKF) and Unscented Kalman filter (UKF) were compared in pursuit of better accuracy and reliability in this nonlinear estimation problem, using only on-board low cost MEMS sensors. Experimental results confirmed the viability of the proposed algorithms and the sensor suite, for low cost and low weight micro planetary rovers. It is demonstrated that integrating the relative and absolute navigation MEMS sensors reduces the navigation errors to the desired level.

  10. Beginnings of Satellite Navigation

    Directory of Open Access Journals (Sweden)

    Miljenko Solarić

    2008-05-01

    Full Text Available The first satellite navigation system called the Navy Navigation Satellite System (NNSS or TRANSIT was planned in the USA in 1958. It consisted of 5-6 artificial Earth satellites, was set in motion for the USA military in 1964, and in 1967 for civilian purposes. The frequency shift of received radio waves emitted from the satellite and caused by the Doppler effect was measured. The TRANSIT satellite speed of approaching or moving away was derived from that; the TRANSIT satellites emmited also their own coordinates. Then the ship's position was determined by an intersection of three hyperboloids, which were determined from differences of distances in three time intervals. Maintenance of this navigation system was stopped in 1996, but it is still being used in the USA Navy for exploring the ionosphere. Furthermore, results of Doppler measurements in international projects at the Hvar Observatory from 1982 and 1983. This was the first time in Croatia and the former country that the coordinates of the Hvar Observatory were determined in the unique world coordinate system WGS'72. The paper ends with a brief representation of the Tsiklon Doppler navigation system produced in the former Soviet Union, and there is a list of some of numerous produced and designed satellite navigation systems.Ključne riječi

  11. Navigating Distributed Services

    DEFF Research Database (Denmark)

    Beute, Berco

    2002-01-01

    , to a situation where they are distributedacross the Internet. The second trend is the shift from a virtual environment that solelyconsists of distributed documents to a virtual environment that consists of bothdistributed documents and distributed services. The third and final trend is theincreasing diversity...... of devices used to access information on the Internet.The focal point of the thesis is an initial exploration of the effects of the trends onusers as they navigate the virtual environment of distributed documents and services.To begin the thesis uses scenarios as a heuristic device to identify and analyse...... themain effects of the trends. This is followed by an exploration of theory of navigationInformation Spaces, which is in turn followed by an overview of theories, and the stateof the art in navigating distributed services. These explorations of both theory andpractice resulted in a large number of topics...

  12. Navigational Planning in Orienteering

    Science.gov (United States)

    Murakoshi, Shin

    Navigation is a human activity with the aim being to arrive at a predetermined destination. In order to find the way to the destination, the use of current input from the actual environment while travelling is needed as well as stored and organized knowledge of the local geography. Although the knowledge requirement has been studied extensively in the form of cognitive maps or other spatial representation, few studies deal with how the knowledge is used together with the input from the actual environment while navigating.

  13. Nautical Navigation Aids (NAVAID) Locations

    Data.gov (United States)

    Department of Homeland Security — Structures intended to assist a navigator to determine position or safe course, or to warn of dangers or obstructions to navigation. This dataset includes lights,...

  14. Inland Electronic Navigational Charts (IENC)

    Data.gov (United States)

    Army Corps of Engineers, Department of the Army, Department of Defense — These Inland Electronic Navigational Charts (IENCs) were developed from available data used in maintenance of Navigation channels. Users of these IENCs should be...

  15. Micro-arcsecond Celestial Reference Frames: definition and realization - Impact of the recent IAU Resolutions

    Institute of Scientific and Technical Information of China (English)

    Nicole Capitaine

    2012-01-01

    The adoption of the International Celestial Reference System (ICRS),based on Very Long Baseline Interferometry (VLBI) observations of extragalactic radiosources by the International Astronomical Union (IAU) since 1998 January 1,opened a new era for astronomy.The ICRS and the corresponding frame,the International Celestial Reference Frame (ICRF),replaced the Fundamental Catalog (FK5) based on positions and proper motions of bright stars,with the Hipparcos catalog being adopted as the primary realization of the ICRS in optical wavelengths.According to its definition,the ICRS is such that the barycentric directions of distant extragalactic objects show no global rotation with respect to these objects; this provides a quasi-inertial reference for measuring the positions and angular motions of the celestial objects.Other resolutions on reference systems were passed by the IAU in 2000 and 2006 and endorsed by the International Union of Geodesy and Geophysics (IUGG) in 2003 and 2007,respectively.These especially concern the definition and realization of the astronomical reference systems in the framework of general relativity and transformations between them.First,the IAU 2000 resolutions refined the concepts and definition of the astronomical reference systems and parameters for Earth's rotation,and adopted the IAU 2000 precession-nutation.Then,the IAU 2006 resolutions adopted a new precession model that is consistent with dynamical theories; they also addressed definition,terminology or orientation issues relative to reference systems and time scales that needed to be specified after the adoption of the IAU 2000 resolutions.An additional IUGG 2007 resolution defined the International Terrestrial Reference System (ITRS) so that it strictly complies with the IAU recommendations.Finally,the IAU 2009 resolutions adopted a new system of astronomical constants and an improved realization of the ICRF.These fundamental changes have led to significant improvements in the fields

  16. Spectrum of the Anomalous Microwave Emission in the North Celestial Pole with WMAP 7-Year data

    CERN Document Server

    Bonaldi, Anna; 10.1155/2012/853927

    2013-01-01

    We estimate the frequency spectrum of the diffuse anomalous microwave emission (AME) on the North Celestial Pole (NCP) region of the sky with the Correlated Component Analysis (CCA) component separation method applied to WMAP 7-yr data. The NCP is a suitable region for this analysis because the AME is weakly contaminated by synchrotron and free-free emission. By modeling the AME component as a peaked spectrum we estimate the peak frequency to be $21.7\\pm0.8$\\,GHz, in agreement with previous analyses which favored $\

  17. Brightness and color of the integrated starlight at celestial, ecliptic and galactic poles

    CERN Document Server

    Nawar, S; Mikhail, J S; Morcos, A B

    2010-01-01

    From photoelectric observations of night sky brightness carried out at Abu-Simbel, Asaad et al. (1979) have obtained values of integrated starlight brightness at different Galactic latitudes. These data have been used in the present work to obtain the brightness and color of the integrated starlight at North and South Celestial, Ecliptic and Galactic Poles. The present values of the brightness are expressed in S10 units and mag/arcsec2. Our results have been compared with that obtained by other investigators using photometric and star counts techniques. The B-V and B-R have been calculated and the results are compared with that obtained by other investigators.

  18. Method of separation of celestial gamma-ray bursts from solar flares

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, K.W.; White, R.S. (Institute of Geophysics and Planetary Physics, UC Riverside, California 92521 (United States)); Klebesadel, R.W.; Laros, J.G. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))

    1991-09-01

    We recently discovered 217 new'' celestial gamma-ray burst candidates from the new'' burst search of the PVO real time data base.[sup 1] The burst search covered the time period from September 1978 to July 1988. Sixty were confirmed by at lest on other spacecraft, e.g., ISEE-3, V-11, V-12, etc. None triggered the PVO high time resolution memory. In this paper we describe a new algorithm based ont eh relationship between time width [ital T][sub [ital w

  19. The ICRF-3: Status, plans, and progress on the next generation International Celestial Reference Frame

    CERN Document Server

    Malkin, Z; Arias, F; Boboltz, D; Boehm, J; Bolotin, S; Bourda, G; Charlot, P; De Witt, A; Fey, A; Gaume, R; Heinkelmann, R; Lambert, S; Ma, C; Nothnagel, A; Seitz, M; Gordon, D; Skurikhina, E; Souchay, J; Titov, O

    2015-01-01

    The goal of this presentation is to report the latest progress in creation of the next generation of VLBI-based International Celestial Reference Frame, ICRF3. Two main directions of ICRF3 development are improvement of the S/X-band frame and extension of the ICRF to higher frequencies. Another important task of this work is the preparation for comparison of ICRF3 with the new generation optical frame GCRF expected by the end of the decade as a result of the Gaia mission.

  20. Celestial harvest 300-plus showpieces of the heavens for telescope viewing and contemplation

    CERN Document Server

    Mullaney, James

    2012-01-01

    This book describes over 300 celestial wonders that can be viewed with common binoculars and low-power ""backyard"" telescopes incorporating refractors and reflectors.In addition to such showpieces as the Andromeda Galaxy, the largest and brightest of all galaxies after the Milky Way, and the Blue Snowball, one of the autumn sky's outstanding planetary nebulas, over 20 other special objects are listed and characterized, many of which are visible to the unaided eye on a dark, clear night.The sun, moon, Venus, Mars, Jupiter, Saturn, and other members of the earth's solar system are also describ

  1. Personal Navigation System

    Science.gov (United States)

    2005-10-31

    GPS Satellite Simulator PC I B us PC I B us Embedded C language software TMS320VC33 DSP • Sensor I/O • Navigation Equations • Deep Integration...Simulator Test Display Simulation Controller 22 Figure 12. PNS Prototype Software System Integration Environment Embedded C language

  2. Navigating Hypermasculine Terrains

    DEFF Research Database (Denmark)

    Henriksen, Ann-Karina Eske

    2015-01-01

    The study addresses how young women navigate urban terrains that are characterized by high levels of interpersonal aggression and crime. It is argued that young women apply a range of gendered tactics to establish safety and social mastery, and that these are framed by the limits and possibilitie...

  3. The attack navigator

    DEFF Research Database (Denmark)

    Probst, Christian W.; Willemson, Jan; Pieters, Wolter

    2016-01-01

    -technical system, the attack navigator identifies routes to an attacker goal. Specific attacker properties such as skill or resources can be included through attacker profiles. This enables defenders to explore attack scenarios and the effectiveness of defense alternatives under different threat conditions....

  4. Navigating in higher education

    DEFF Research Database (Denmark)

    Thingholm, Hanne Balsby; Reimer, David; Keiding, Tina Bering

    Denne rapport er skrevet på baggrund af spørgeskemaundersøgelsen – Navigating in Higher Education (NiHE) – der rummer besvarelser fra 1410 bachelorstuderende og 283 undervisere fordelt på ni uddannelser fra Aarhus Universitet: Uddannelsesvidenskab, Historie, Nordisk sprog og litteratur...

  5. 33 CFR 401.53 - Obstructing navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Obstructing navigation. 401.53 Section 401.53 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.53...

  6. Control algorithms for autonomous robot navigation

    Energy Technology Data Exchange (ETDEWEB)

    Jorgensen, C.C.

    1985-09-20

    This paper examines control algorithm requirements for autonomous robot navigation outside laboratory environments. Three aspects of navigation are considered: navigation control in explored terrain, environment interactions with robot sensors, and navigation control in unanticipated situations. Major navigation methods are presented and relevance of traditional human learning theory is discussed. A new navigation technique linking graph theory and incidental learning is introduced.

  7. On one-way Doppler measurements of space craft and celestial objects

    Science.gov (United States)

    Jochim, E. F. M.

    2010-01-01

    The orbital velocity of a spacecraft and other celestial objects is monitored by observing the Doppler frequency shift of the signals received at the ground station. This is possible one-way in case the transmitted frequency is stable enough. In most spacecraft a calibrated transponder allows two-way Doppler frequency registrations. In general, the factor 2 is expected as the quotient between two- and one-way frequencies. However, this is no longer the case when the motion of the observed object deviates from the orbit as predicted. Frequency differences appear. Porsche (1999) has published a formula to describe these differences based on the assumption of a double projection of the true velocity vector. In the present paper a more sophisticated analysis of the influence of state errors on the track-ing results is deduced. This theory has been tested by the Doppler measurements during flybys of the comet space probe GIOTTO penetrating through the comae of the comets P/Halley and P/Grigg-Skjellerup. One-way Doppler measurements of the low Earth satellites CHAMP and TERRASAR-X show a tendency for the applicability of this approach. Finally, some conse-quences for the observation of other celestial objects are discussed.

  8. Integrated navigation method based on inertial navigation system and Lidar

    Science.gov (United States)

    Zhang, Xiaoyue; Shi, Haitao; Pan, Jianye; Zhang, Chunxi

    2016-04-01

    An integrated navigation method based on the inertial navigational system (INS) and Lidar was proposed for land navigation. Compared with the traditional integrated navigational method and dead reckoning (DR) method, the influence of the inertial measurement unit (IMU) scale factor and misalignment was considered in the new method. First, the influence of the IMU scale factor and misalignment on navigation accuracy was analyzed. Based on the analysis, the integrated system error model of INS and Lidar was established, in which the IMU scale factor and misalignment error states were included. Then the observability of IMU error states was analyzed. According to the results of the observability analysis, the integrated system was optimized. Finally, numerical simulation and a vehicle test were carried out to validate the availability and utility of the proposed INS/Lidar integrated navigational method. Compared with the test result of a traditional integrated navigation method and DR method, the proposed integrated navigational method could result in a higher navigation precision. Consequently, the IMU scale factor and misalignment error were effectively compensated by the proposed method and the new integrated navigational method is valid.

  9. Invisible Navigation (or Impossible?).

    OpenAIRE

    Özcan, Oğuzhan; O'Neil, Mary Lou

    2013-01-01

    Abstract: This article introduces an experimental artwork on moving mobile interfaces. It aims to answer the question: Is it possible to navigate a part of a large image composition, moving a smaller interface of a mobile device in a certain direction such as left and right, back and forth or up and down? The article then outlines the new concept of “Invisible (or impossible) Navigation” and discusses the output of artistic practices which address the “Labyrinth of Art”.

  10. Self-navigating robot

    Science.gov (United States)

    Thompson, A. M.

    1978-01-01

    Rangefinding equipment and onboard navigation system determine best route from point to point. Research robot has two TV cameras and laser for scanning and mapping its environment. Path planner finds most direct, unobstructed route that requires minimum expenditure of energy. Distance is used as measure of energy expense, although other measures such as time or power consumption (which would depend on the topography of the path) may be used.

  11. Waves at Navigation Structures

    Science.gov (United States)

    2014-10-27

    ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as Report (SAR) 18. NUMBER OF PAGES 2 19a. NAME...upgrades the Coastal Modeling System’s ( CMS ) wave model CMS -Wave, a phase-averaged spectral wave model, and BOUSS-2D, a Boussinesq-type nonlinear wave...provided by this work unit address these critical needs of the Corps’ navigation mission. Description Issue Addressed CMS -Wave application at Braddock

  12. Multisensor robot navigation system

    Science.gov (United States)

    Persa, Stelian; Jonker, Pieter P.

    2002-02-01

    Almost all robot navigation systems work indoors. Outdoor robot navigation systems offer the potential for new application areas. The biggest single obstacle to building effective robot navigation systems is the lack of accurate wide-area sensors for trackers that report the locations and orientations of objects in an environment. Active (sensor-emitter) tracking technologies require powered-device installation, limiting their use to prepared areas that are relative free of natural or man-made interference sources. The hybrid tracker combines rate gyros and accelerometers with compass and tilt orientation sensor and DGPS system. Sensor distortions, delays and drift required compensation to achieve good results. The measurements from sensors are fused together to compensate for each other's limitations. Analysis and experimental results demonstrate the system effectiveness. The paper presents a field experiment for a low-cost strapdown-IMU (Inertial Measurement Unit)/DGPS combination, with data processing for the determination of 2-D components of position (trajectory), velocity and heading. In the present approach we have neglected earth rotation and gravity variations, because of the poor gyroscope sensitivities of our low-cost ISA (Inertial Sensor Assembly) and because of the relatively small area of the trajectory. The scope of this experiment was to test the feasibility of an integrated DGPS/IMU system of this type and to develop a field evaluation procedure for such a combination.

  13. Research on CNS/SINS Integrated Navigation by Simulation%基于星敏感器的天文/惯导组合导航仿真研究

    Institute of Scientific and Technical Information of China (English)

    罗宁; 周磊; 张锐; 樊建文

    2014-01-01

    本文通过仿真实验,研究了基于星敏感器的天文/惯导组合导航系统的导航性能和特点。首先分析了天文导航的基本原理,并给出了天文/惯导组合导航算法的理论模型。在此基础上,建立了天文导航和捷联惯性导航的仿真模型,实现了天文/惯导组合导航系统仿真。仿真结果表明:基于星敏感器的天文/惯导组合导航能够有效抑制惯导的长时漂移累积误差,有利于实现机载远程长航时的高精度导航。%According to the simulation experiments, the performance and characteristic of CNS/INS integrated navigation are analyzed in this paper. Firstly, the basic theory of celestial navigation is discussed, and the algorithm of CNS/INS integrated navigation is presented. Then, the celestial navigation and inertial navigation simulation models are set up. What’s more, the CNS/INS integrated navigation simulation system is realized. The simulation results show that the accumulative errors of inertial navigation are checked effectively by the CNS/INS integrated navigation, which is benefit to realize the high precision airborne navigation with long-distance and long-endurance.

  14. Is the aether entrained by the motion of celestial bodies? What do the experiments tell us?

    CERN Document Server

    Levy, Joseph

    2012-01-01

    Even though the concept has evolved and if the designation as aether is improperly regarded as outdated, nobody today considers that the vacuum is empty. However, the nature and the properties of the substratum, which permeates the entire universe, remain for the most part unspecified. For example, divergent opinions are put forward by physicists about a possible dragging of the aether by the translational motion of celestial bodies due to gravitation. We show in this text that such a hypothesis is inconsistent with well established experimental data which, on the contrary, lend support to non-entrained aether theory based on Lorentz contraction. A revaluation of the aether drift to which the Earth is subjected is carried out.

  15. A STUDY ON LOWER SECONDARY SCHOOL PUPILS’ PERCEPTIONS OF CERTAIN ASTRONOMICAL PHENOMENA AND CELESTIAL BODIES

    Directory of Open Access Journals (Sweden)

    VIRGINIA SASU

    2014-01-01

    Full Text Available The main purpose of this paper is to reveal certain misconceptions of astronomical phenomena and of celestial bodies that lower secondary school pupils have and which might represent an obstacle in the process of acquiring knowledge of astronomy, geography, and physics. We applied a questionnaire to a group of 26 pupils in the 6th grade at Colegiul Naţional Pedagogic „Gh. Lazăr” (“Gh. Lazăr National Pedagogical College in Cluj-Napoca, in the school year 2010 – 2011. The questionnaire consisted of six independent topics: the alternation of day and night, the seasons, the Moon, the solar system, the constellations and the speed of light. Pupils’ answers to these questions emphasize the importance of the study of astronomy as a school subject in order to facilitate building up appropriate mind constructs of the highest degree of objectivity about the world, about the environment we live in.

  16. Signature of the celestial spheres discovering order in the solar system

    CERN Document Server

    Warm, Harmut

    2010-01-01

    "A milestone in modern research on the the harmony of the spheres." - Novalis magazine "This book reignites the debate on the harmony of the spheres." - Das Goetheanum Is the solar system ordered, or is it simply the result of random and chaotic accidents? This book takes us on a powerful and compelling journey of discovery, revealing the celestial spheres' astonishingly complex patterns. The movements of the planets are found to correspond accurately with simple geometric figures and musical intervals, pointing to an exciting new perspective on the ancient idea of a "harmony of the spheres". Hartmut Warm's detailed presentation incorporates the distances, velocities and periods of conjunction of the planets, as well as the rotations of the Sun, Moon and Venus. Numerous graphics - including colour plates - illustrate the extraordinary beauty of the geometrical forms that result when the movements of several planets are viewed in relation to one another. In addition, the author describes and analyses the conce...

  17. SAS-2 observations of celestial diffuse gamma radiation above 30 MeV

    Science.gov (United States)

    Thompson, D. J.; Fichtel, C. E.; Kniffen, D. A.; Hartman, R. C.

    1974-01-01

    The small astronomy satellite, SAS-2, used a 32-deck magnetic core digitized spark chamber to study gamma rays with energies above 30 MeV. Data for four regions of the sky away from the galactic plane were analyzed. These regions show a finite, diffuse flux of gamma rays with a steep energy spectrum, and the flux is uniform over all the regions. Represented by a power law, the differential energy spectrum shows an index of 2.5 + or - 0.4. The steep SAS-2 spectrum and the lower energy data are reasonably consistent with a neutral pion gamma-ray spectrum which was red-shifted (such as that proposed by some cosmological theories). It is concluded that the diffuse celestial gamma ray spectrum observed presents the possibility of cosmological studies and possible evidence for a residual cosmic ray density, and supports the galactic superclusters of matter and antimatter remaining from baryon-symmetric big bang.

  18. International Celestial Reference Frame (ICRF): mantenimiento y extensión

    Science.gov (United States)

    Ma, C.; Arias, E. F.; Eubanks, T.; Fey, A. L.; Gontier, A.-M.; Jacobs, C. S.; Sovers, O. J.; Archinal, B. A.; Charlot, P.

    A partir de enero de 1998 el sistema de referencia celeste convencional está representado por el International Celestial Reference System (ICRS) y materializado a través de las coordenadas VLBI del conjunto de radiofuentes extragalácticas que conforman el International Celestial Reference Frame (ICRF). La primera realización del ICRF, fue elaborada en 1995 por un grupo de expertos designado por la IAU, la que encomendó al International Earth Rotation Service el mantenimiento del ICRS, del ICRF y del vínculo con marcos de referencia en otras frecuencias. Una primera extensión del ICRF se realizó entre abril y junio de 1999, con el objetivo primario de proveer posiciones de radiofuentes extragalácticas observadas a partir de julio de 1995 y de mejorar las posiciones de las fuentes ``candidatas" con la inclusión de observaciones adicionales. Objetivos secundarios fueron monitorear a las radiofuentes para verificar que siguen siendo adecuadas para realizar al ICRF y mejorar las técnicas de análisis de datos. Como resultado del nuevo análisis se obtuvo una solución a partir de la cual se construyó la primera extensión del ICRF, denominada ICRF - Ext.1. Ella representa al ICRS, sus fuentes de definición se mantienen con las mismas posiciones y errores que en la primera realización del ICRF; las demás radiofuentes tienen coordenadas mejor determinadas que en ICRF; el marco de referencia se densificó con el agregado de 59 nuevas radiofuentes.

  19. Understanding satellite navigation

    CERN Document Server

    Acharya, Rajat

    2014-01-01

    This book explains the basic principles of satellite navigation technology with the bare minimum of mathematics and without complex equations. It helps you to conceptualize the underlying theory from first principles, building up your knowledge gradually using practical demonstrations and worked examples. A full range of MATLAB simulations is used to visualize concepts and solve problems, allowing you to see what happens to signals and systems with different configurations. Implementation and applications are discussed, along with some special topics such as Kalman Filter and Ionosphere. W

  20. China Satellite Navigation Conference

    CERN Document Server

    Liu, Jingnan; Fan, Shiwei; Wang, Feixue

    2016-01-01

    These Proceedings present selected research papers from CSNC2016, held during 18th-20th May in Changsha, China. The theme of CSNC2016 is Smart Sensing, Smart Perception. These papers discuss the technologies and applications of the Global Navigation Satellite System (GNSS), and the latest progress made in the China BeiDou System (BDS) especially. They are divided into 12 topics to match the corresponding sessions in CSNC2016, which broadly covered key topics in GNSS. Readers can learn about the BDS and keep abreast of the latest advances in GNSS techniques and applications.

  1. Underwater Navigation using Pseudolite

    Directory of Open Access Journals (Sweden)

    Krishneshwar Tiwary

    2011-07-01

    Full Text Available Using pseudolite or pseudo satellite, a proven technology for ground and space applications for the augmentation of GPS, is proposed for underwater navigation. Global positioning systems (GPS like positioning for underwater system, needs minimum of four pseudolite-ranging signals for pseudo-range and accumulated delta range measurements. Using four such measurements and using the models of underwater attenuation and delays, the navigation solution can be found. However, for application where the one-way ranging does not give good accuracy, alternative algorithms based upon the bi-directional and self-difference ranging is proposed using selfcalibrated pseudolite array algorithm. The hardware configuration is proposed for pseudolite transceiver for making the self-calibrated array. The pseudolite array, fixed or moored under the sea, can give position fixing similar to GPS for underwater applications.Defence Science Journal, 2011, 61(4, pp.331-336, DOI:http://dx.doi.org/10.14429/dsj.61.1087

  2. Learning for Autonomous Navigation

    Science.gov (United States)

    Angelova, Anelia; Howard, Andrew; Matthies, Larry; Tang, Benyang; Turmon, Michael; Mjolsness, Eric

    2005-01-01

    Robotic ground vehicles for outdoor applications have achieved some remarkable successes, notably in autonomous highway following (Dickmanns, 1987), planetary exploration (1), and off-road navigation on Earth (1). Nevertheless, major challenges remain to enable reliable, high-speed, autonomous navigation in a wide variety of complex, off-road terrain. 3-D perception of terrain geometry with imaging range sensors is the mainstay of off-road driving systems. However, the stopping distance at high speed exceeds the effective lookahead distance of existing range sensors. Prospects for extending the range of 3-D sensors is strongly limited by sensor physics, eye safety of lasers, and related issues. Range sensor limitations also allow vehicles to enter large cul-de-sacs even at low speed, leading to long detours. Moreover, sensing only terrain geometry fails to reveal mechanical properties of terrain that are critical to assessing its traversability, such as potential for slippage, sinkage, and the degree of compliance of potential obstacles. Rovers in the Mars Exploration Rover (MER) mission have got stuck in sand dunes and experienced significant downhill slippage in the vicinity of large rock hazards. Earth-based off-road robots today have very limited ability to discriminate traversable vegetation from non-traversable vegetation or rough ground. It is impossible today to preprogram a system with knowledge of these properties for all types of terrain and weather conditions that might be encountered.

  3. 33 CFR 207.185 - Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation. 207.185 Section 207.185 Navigation and... § 207.185 Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and...

  4. Introductory Course on Satellite Navigation

    Science.gov (United States)

    Giger, Kaspar; Knogl, J. Sebastian

    2012-01-01

    Satellite navigation is widely used for personal navigation and more and more in precise and safety-critical applications. Thus, the subject is suited for attracting the interest of young people in science and engineering. The practical applications allow catching the students' attention for the theoretical background. Educational material on the…

  5. Autonomous Spacecraft Navigation With Pulsars

    CERN Document Server

    Becker, Werner; Jessner, Axel

    2013-01-01

    An external reference system suitable for deep space navigation can be defined by fast spinning and strongly magnetized neutron stars, called pulsars. Their beamed periodic signals have timing stabilities comparable to atomic clocks and provide characteristic temporal signatures that can be used as natural navigation beacons, quite similar to the use of GPS satellites for navigation on Earth. By comparing pulse arrival times measured on-board a spacecraft with predicted pulse arrivals at a reference location, the spacecraft position can be determined autonomously and with high accuracy everywhere in the solar system and beyond. The unique properties of pulsars make clear already today that such a navigation system will have its application in future astronautics. In this paper we describe the basic principle of spacecraft navigation using pulsars and report on the current development status of this novel technology.

  6. Long-term Dynamical Behavior of Highly Perturbed Natural and Artificial Celestial Bodies

    Science.gov (United States)

    Rosengren, Aaron J.

    This thesis explores the dynamical evolution of celestial bodies, both natural and artificial, which are strongly perturbed by solar radiation pressure---a non-gravitational force that has played an increasingly important role in celestial mechanics since the early 1900s. The particular focus is on the high area-to-mass ratio (HAMR) space debris discovered in near geosynchronous Earth orbit (GEO) through optical observations in 2004, and on micron-sized circumplanetary dust particles in the outer Saturnian system. The formalism developed can also be applied to---and, indeed, was unquestionably influenced by---the orbital motion of spacecraft about small bodies (asteroids and comets). The chief difficulties which arise in getting an accurate understanding of the motion of such bodies in highly perturbed dynamical environments come, in part, from the nonlinearity of the dynamical system, but more so from the inadequacy of the classical approaches and methods. While modern formulations based on numerical integrations can give "precise" solutions for specific initial conditions, these afford little insight into the nature of the problem or the essential dependence of the perturbed motion on the system parameters. The predominant perturbations acting on HAMR objects and circumplanetary dust grains are solar radiation pressure, planetary oblateness, and third-body gravitational interactions induced by the Sun and nearby natural satellites. We developed first-order averaged models, based on the Milankovitch formulation of perturbation theory, which govern the long-term evolution of orbits subject to these perturbing forces. The unexpectedly rich results obtained by the use of this vector formalism are due to certain important circumstances in celestial and quantum mechanics which gave rise to its origin and development. An attempt has been made to trace these historical developments and to put them into the perspective of the present. The averaged equations of motion hold

  7. Navigation System of Marks Areas - USACE IENC

    Data.gov (United States)

    Department of Homeland Security — These inland electronic Navigational charts (IENCs) were developed from available data used in maintenance of Navigation channels. Users of these IENCs should be...

  8. Dynamic Transportation Navigation

    Science.gov (United States)

    Meng, Xiaofeng; Chen, Jidong

    Miniaturization of computing devices, and advances in wireless communication and sensor technology are some of the forces that are propagating computing from the stationary desktop to the mobile outdoors. Some important classes of new applications that will be enabled by this revolutionary development include intelligent traffic management, location-based services, tourist services, mobile electronic commerce, and digital battlefield. Some existing application classes that will benefit from the development include transportation and air traffic control, weather forecasting, emergency response, mobile resource management, and mobile workforce. Location management, i.e., the management of transient location information, is an enabling technology for all these applications. In this chapter, we present the applications of moving objects management and their functionalities, in particular, the application of dynamic traffic navigation, which is a challenge due to the highly variable traffic state and the requirement of fast, on-line computations.

  9. Application of X-Ray Pulsar Navigation: A Characterization of the Earth Orbit Trade Space

    Science.gov (United States)

    Yu, Wayne Hong

    2016-01-01

    The potential for pulsars as a navigation source has been studied since their discovery in 1967. X-ray pulsar navigation (XNAV) is a celestial navigation system that uses the consistent timing nature of x-ray photons from millisecond pulsars (MSP) to perform space navigation. By comparing the detected arrival of x-ray photons to a reference database of expected pulsar light-curve timing models, one can infer a range and range rate measurement based on light time delay. Much of the challenge of XNAV comes from the faint signal, availability, and distant nature of pulsars. This is a study of potential pulsar XNAV measurements to measure extended Kalman filter (EKF) tracking performance with a wide trade space of bounded Earth orbits, using a simulation of existing x-ray detector space hardware. An example of an x-ray detector for XNAV is the NASA Station Explorer for X-ray Timing and Navigation (SEXTANT) mission, a technology demonstration of XNAV set to perform on the International Space Station (ISS) in late 2016early 2017. XNAV hardware implementation is driven by trajectory and environmental influences which add noise to the x-ray pulse signal. In a closed Earth orbit, the radiation environment can exponentially increase the signal noise from x-ray pulsar sources, decreasing the quality and frequency of measurements. The SEXTANT mission in particular improves on the signal to noise ratio by focusing an array of 56 x-ray silicon drift detectors at one pulsar target at a time. This reduces timing glitches and other timing noise contributions from ambient x-ray sources to within a 100 nanosecond resolution. This study also considers the SEXTANT scheduling challenges inherent in a single target observation. Finally, as the navigation sources are now relatively inertial targets, XNAV measurements are also subject to periods of occultation from various celestial bodies. This study focuses on the characterization of these drivers in closed Earth orbits and is not a

  10. Status of GRAIL Gravity Field Determination Using the Celestial Mechanics Approach

    Science.gov (United States)

    Arnold, Daniel; Beutler, Gerhard; Jäggi, Adrian; Bock, Heike; Mervart, Leos; Meyer, Ulrich; Bertone, Stefano

    To determine the gravity field of the Moon, the NASA mission GRAIL (Gravity Recovery And Interior Laboratory) inherits its concept from the Earth orbiting GRACE (Gravity Recovery and Climate Experiment) mission. The use of ultra-precise inter-satellite Ka-band ranging observations enables data acquisition even when the spacecraft are not tracked from the Earth. The data allows for a highly accurate estimation of the lunar gravity field with unprecedented resolution on both sides of the Moon, which is crucial to improve the understanding of its internal structure and thermal evolution. In this presentation we discuss GRAIL-based lunar gravity fields generated with the Celestial Mechanics Approach. Ka-band range-rate (KBRR) observations and position data (GNI1B products) are used to solve for the lunar gravity field parameters in a generalized orbit determination problem. Apart from normalized spherical harmonic coefficients up to degrees n≤ 200, also arc- and satellite-specific parameters, like initial state vectors and pseudo-stochastic pulses, are set up as common parameters for all measurement types. The latter shall compensate for imperfect models of non-gravitational accelerations, e.g., caused by solar radiation pressure. In addition, especially for the data of the primary mission phase, it is essential to estimate time bias parameters for the KBRR observations. We compare our results from the nominal mission phase with the official Level 2 gravity field models first released in October 2013. Our results demonstrate that the lunar gravity field can be recovered with a high quality by adapting the Celestial Mechanics Approach, even when using pre-GRAIL or pre-SELENE gravity field models as a priori fields and when replacing sophisticated models of non-gravitational accelerations by appropriately spaced and constrained pseudo-stochastic pulses. Yet, the usage of preprocessed position data as pseudo observations is not fully satisfying and is potentially

  11. Periodic, Quasi-Periodic and Chaotic Motions in Celestial Mechanics: Theory and Applications Selected papers from the Fourth Meeting on Celestial Mechanics, CELMEC IV San Martino al Cimino (Italy), 11–16 September 2005

    CERN Document Server

    Celletti, A

    2006-01-01

    The book provides the most recent advances of Celestial Mechanics, as provided by high-level scientists working in this field. It covers theoretical investigations as well as applications to concrete problems. Outstanding review papers are included in the book and they introduce the reader to leading subjects, like the variational approaches to find periodic orbits, the stability theory of the N-body problem, the spin-orbit resonances and chaotic dynamics, the space debris polluting the circumterrestrial space.

  12. 33 CFR 66.10-15 - Aids to navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Aids to navigation. 66.10-15 Section 66.10-15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Uniform State Waterway Marking System § 66.10-15 Aids to navigation....

  13. Lunar Navigation Architecture Design Considerations

    Science.gov (United States)

    D'Souza, Christopher; Getchius, Joel; Holt, Greg; Moreau, Michael

    2009-01-01

    The NASA Constellation Program is aiming to establish a long-term presence on the lunar surface. The Constellation elements (Orion, Altair, Earth Departure Stage, and Ares launch vehicles) will require a lunar navigation architecture for navigation state updates during lunar-class missions. Orion in particular has baselined earth-based ground direct tracking as the primary source for much of its absolute navigation needs. However, due to the uncertainty in the lunar navigation architecture, the Orion program has had to make certain assumptions on the capabilities of such architectures in order to adequately scale the vehicle design trade space. The following paper outlines lunar navigation requirements, the Orion program assumptions, and the impacts of these assumptions to the lunar navigation architecture design. The selection of potential sites was based upon geometric baselines, logistical feasibility, redundancy, and abort support capability. Simulated navigation covariances mapped to entry interface flightpath- angle uncertainties were used to evaluate knowledge errors. A minimum ground station architecture was identified consisting of Goldstone, Madrid, Canberra, Santiago, Hartebeeshoek, Dongora, Hawaii, Guam, and Ascension Island (or the geometric equivalent).

  14. Conference on Hamiltonian Systems and Celestial Mechanics 2014 & Workshop on Virus Dynamics and Evolution : Extended Abstracts Spring 2014

    CERN Document Server

    Cors, Josep; Llibre, Jaume; Korobeinikov, Andrei

    2015-01-01

    The two parts of the present volume contain extended conference abstracts corresponding to selected talks given by participants at the "Conference on Hamiltonian Systems and Celestial Mechanics 2014" (HAMSYS2014) (15 abstracts) and at the "Workshop on Virus Dynamics and Evolution" (12 abstracts), both held at the Centre de Recerca Matemàtica (CRM) in Barcelona from June 2nd to 6th, 2014, and from June 23th to 27th, 2014, respectively. Most of them are brief articles, containing preliminary presentations of new results not yet published in regular research journals. The articles are the result of a direct collaboration between active researchers in the area after working in a dynamic and productive atmosphere. The first part is about Central Configurations, Periodic Orbits and Hamiltonian Systems with applications to Celestial Mechanics – a very modern and active field of research. The second part is dedicated to mathematical methods applied to viral dynamics and evolution. Mathematical modelling of biologi...

  15. Non-linear VLBI station motions and their impact on the celestial reference frame and Earth orientation parameters.

    Science.gov (United States)

    Krásná, Hana; Malkin, Zinovy; Böhm, Johannes

    The increasing accuracy and growing time span of Very Long Baseline Interferometry (VLBI) observations allow the determination of seasonal signals in station positions which still remain unmodelled in conventional analysis approaches. In this study we focus on the impact of the neglected seasonal signals in the station displacement on the celestial reference frame and Earth orientation parameters. We estimate empirical harmonic models for selected stations within a global solution of all suitable VLBI sessions and create mean annual models by stacking yearly time series of station positions which are then entered a priori in the analysis of VLBI observations. Our results reveal that there is no systematic propagation of the seasonal signal into the orientation of celestial reference frame but position changes occur for radio sources observed non-evenly over the year. On the other hand, the omitted seasonal harmonic signal in horizontal station coordinates propagates directly into the Earth rotation parameters causing differences of several tens of microarcseconds.

  16. Chaos in navigation satellite orbits caused by the perturbed motion of the Moon

    CERN Document Server

    Rosengren, Aaron J; Rossi, Alessandro; Valsecchi, Giovanni B

    2015-01-01

    Numerical simulations carried out over the past decade suggest that the orbits of the Global Navigation Satellite Systems are unstable, resulting in an apparent chaotic growth of the eccentricity. Here we show that the irregular and haphazard character of these orbits reflects a similar irregularity in the orbits of many celestial bodies in our Solar System. We find that secular resonances, involving linear combinations of the frequencies of nodal and apsidal precession and the rate of regression of lunar nodes, occur in profusion so that the phase space is threaded by a devious stochastic web. As in all cases in the Solar System, chaos ensues where resonances overlap. These results may be significant for the analysis of disposal strategies for the four constellations in this precarious region of space.

  17. Edward Burne-Jones’ The Days of Creation: A Celestial Utopia

    Directory of Open Access Journals (Sweden)

    Liana De Girolami Cheney

    2014-09-01

    Full Text Available Edward Burne-Jones’ cycle of The Days of Creation of 1870-66(Fogg Art Museum, Harvard University Museums, Cambridge, MA was highly praised and elegantly described by Oscar Wilde: “The picture is divided into six compartments, each representing a day in the Creation of the World, under the symbol of an angel holding a crystal globe, within which is shown the work of a day.” This essay examines how Burne-Jones visualized an unusual celestial creation where angels holding magical spheres unveil the divine manifestation for the creation of a terrestrial realm. His The Days of Creation is an aesthetic culmination of the artistic power of invention, imitation and creation of beauty. Burne-Jones borrows the divine concept of world creation to formulate his own artist creation. Selecting God’s week of creation, he empowers a daily angel to manifest the beauty and power of divine creation. Ultimately, Burne-Jones creates a cosmic utopia, a mythical heavenly and natural realm, where angels design a world of beauty to be emulated not only by the artist, but also by most of all by the viewer.

  18. ASTEP South: An Antarctic Search for Transiting ExoPlanets around the celestial South pole

    CERN Document Server

    Crouzet, Nicolas; Agabi, Karim; Rivet, Jean-Pierre; Bondoux, Erick; Challita, Zalpha; Fanteï-Caujolle, Yan; Fressin, François; Mékarnia, Djamel; Schmider, François-Xavier; Valbousquet, Franck; Blazit, Alain; Bonhomme, Serge; Abe, Lyu; Daban, Jean-Baptiste; Gouvret, Carole; Fruth, Thomas; Rauer, Heike; Erikson, Anders; Barbieri, Mauro; Aigrain, Suzanne; Pont, Frédéric

    2009-01-01

    ASTEP South is the first phase of the ASTEP project (Antarctic Search for Transiting ExoPlanets). The instrument is a fixed 10 cm refractor with a 4kx4k CCD camera in a thermalized box, pointing continuously a 3.88 degree x 3.88 degree field of view centered on the celestial South pole. ASTEP South became fully functional in June 2008 and obtained 1592 hours of data during the 2008 Antarctic winter. The data are of good quality but the analysis has to account for changes in the point spread function due to rapid ground seeing variations and instrumental effects. The pointing direction is stable within 10 arcseconds on a daily timescale and drifts by only 34 arcseconds in 50 days. A truly continuous photometry of bright stars is possible in June (the noon sky background peaks at a magnitude R=15 arcsec-2 on June 22), but becomes challenging in July (the noon sky background magnitude is R=12.5 arcsec?2 on July 20). The weather conditions are estimated from the number of stars detected in the field. For the 2008...

  19. Spectrum of the Anomalous Microwave Emission in the North Celestial Pole with WMAP 7-Year Data

    Directory of Open Access Journals (Sweden)

    Anna Bonaldi

    2012-01-01

    Full Text Available We estimate the frequency spectrum of the diffuse anomalous microwave emission (AME on the North Celestial Pole (NCP region of the sky with the Correlated Component Analysis (CCA component separation method applied to WMAP 7-yr data. The NCP is a suitable region for this analysis because the AME is weakly contaminated by synchrotron and free-free emission. By modeling the AME component as a peaked spectrum we estimate the peak frequency to be 21.7±0.8 GHz, in agreement with previous analyses which favored νp < 23 GHz. The ability of our method to correctly recover the position of the peak is verified through simulations. We compare the estimated AME spectrum with theoretical spinning dust models to constrain the hydrogen density nH. The best results are obtained with densities around 0.2–0.3 cm−3, typical of warm ionised medium (WIM to warm neutral medium (WNM conditions. The degeneracy with the gas temperature prevents an accurate determination of nH, especially for low hydrogen ionization fractions, where densities of a few cm−3 are also allowed.

  20. The effects of frequency-dependent quasar evolution on the celestial reference frame

    CERN Document Server

    Shabala, Stanislav; McCallum, Jamie; Titov, Oleg; Blanchard, Jay; Lovell, Jim; Watson, Christopher

    2013-01-01

    We examine the relationship between source position stability and astrophysical properties of radio-loud quasars making up the International Celestial Reference Frame. We construct light curves for 95 most frequently observed ICRF2 quasars at both the geodetic VLBI observing bands. Because the appearance of new quasar components corresponds to an increase in quasar flux density, these light curves allow us to probe source structure on sub-100 microarcsecond scales, much smaller than conventional VLBI imaging. Flux density monitoring also allows us to trace the evolution of quasar structure. We test how source position stability depends on three astrophysical parameters: (1) Flux density variability at X-band; (2) Time lag between S and X-band light curves; (3) Spectral index rms, defined as the variability in the ratio between S and X-band flux densities. We find that small (<0.15 years) time lags between S and X-band light curves and low (<0.10) spectral index variability are excellent indicators of po...

  1. Asymptotic theory of the motion of celestial bodies in the atmosphere

    Science.gov (United States)

    Stulov, V. P.

    2004-04-01

    At a large entry velocity of celestial bodies into the atmosphere, a mass-loss parameter β= σVe2/2 ( σ is the ablation coefficient) is very large. So, for some versions of the 1908 Tunguska event parameters, one has β=5-25. In the case of comet Shoemaker-Levy 9 fragments entry into Jupiter, the parameter β is 75-100. Some stations of European Fireball Network have observed at May, June 1997 two bolides, for which β was estimated as 150 and 40. Therefore, the limiting theory for meteoroid motion in the atmosphere is developed. The solution of meteoric physics equations depends on two (single body) or three parameters (splitting body), and β is among them as argument of some special functions. The asymptotic limit of the solution at β≫1 looks like changing meteoroid mass from entry value to zero at constant velocity. This limit for a single body was compared with observations in May, June 1997 in Czech Republic, and good agreement was achieved. Ultimate models with fragmentation are necessary to understand some real features of large-scale events. So, results of this work show that for large bodies such as Tunguska space body and comet Shoemaker-Levy 9 fragments, we should discuss a motion of gaseous volume after finishing ablation at almost entry velocity. Probably, the big forest fall in 1908 in Siberia and plumes in 1994 on Jupiter are results of such gas jets.

  2. Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Planets and Celestial Calibration Sources

    CERN Document Server

    Weiland, J L; Hill, R S; Wollack, E; Hinshaw, G; Greason, M R; Jarosik, N; Page, L; Bennett, C L; Dunkley, J; Gold, B; Halpern, M; Kogut, A; Komatsu, E; Larson, D; Limon, M; Meyer, S S; Nolta, M R; Smith, K M; Spergel, D N; Tucker, G S; Wright, E L

    2010-01-01

    We present WMAP seven-year observations of bright sources which are often used as calibrators at microwave frequencies. Ten objects are studied in five frequency bands (23 - 94 GHz): the outer planets (Mars, Jupiter, Saturn, Uranus and Neptune) and five fixed celestial sources (Cas A, Tau A, Cyg A, 3C274 and 3C58). The seven-year analysis of Jupiter provides temperatures which are within 1-sigma of the previously published WMAP five-year values, with slightly tighter constraints on variability with orbital phase, and limits (but no detections) on linear polarization. Scaling factors are provided which, when multiplied by the Wright Mars thermal model predictions at 350 micron, reproduce WMAP seasonally averaged observations of Mars within ~2%. An empirical model is described which fits brightness variations of Saturn due to geometrical effects and can be used to predict the WMAP observations to within 3%. Seven-year mean temperatures for Uranus and Neptune are also tabulated. Uncertainties in Uranus temperatu...

  3. Non-parametric PSF estimation from celestial transit solar images using blind deconvolution

    CERN Document Server

    Gonzalez, Adriana; Jacques, Laurent

    2016-01-01

    Context: Characterization of instrumental effects in astronomical imaging is important in order to extract accurate physical information from the observations. Optics are never perfect and the non-ideal path through the telescope is usually represented by the convolution of an ideal image with a Point Spread Function (PSF). Other sources of noise (read-out, Photon) also contaminate the image acquisition process. The problem of estimating both the PSF filter and a denoised image is called blind deconvolution and is ill-posed. Aims: We propose a blind deconvolution scheme that relies on image regularization. Contrarily to most methods presented in the literature, it does not assume a parametric model of the PSF and can thus be applied to any telescope. Methods: Our scheme uses a wavelet analysis image prior model and weak assumptions on the PSF filter's response. We use the observations from a celestial body transit where such object can be assumed to be a black disk. Such constraints limits the interchangeabil...

  4. Initial deep LOFAR observations of Epoch of Reionization windows: I. The North Celestial Pole

    CERN Document Server

    Yatawatta, S; Brentjens, M A; Labropoulos, P; Pandey, V N; Kazemi, S; Zaroubi, S; Koopmans, L V E; Offringa, A R; Jelic, V; Rubi, O Martinez; Veligatla, V; Wijnholds, S J; Brouw, W N; Bernardi, G; Ciardi, B; Daiboo, S; Harker, G; Mellema, G; Schaye, J; Thomas, R; Vedantham, H; Chapman, E; Abdalla, F B; Alexov, A; Anderson, J; Avruch, I M; Batejat, F; Bell, M E; Bell, M R; Bentum, M; Best, P; Bonafede, A; Bregman, J; Breitling, F; van de Brink, R H; Broderick, J W; Bruggen, M; Conway, J; de Gasperin, F; de Geus, E; Duscha, S; Falcke, H; Fallows, R A; Ferrari, C; Frieswijk, W; Garrett, M A; Griessmeier, J M; Gunst, A W; Hassall, T E; Hessels, J W T; Hoeft, M; Iacobelli, M; Juette, E; Karastergiou, A; Kondratiev, V I; Kramer, M; Kuniyoshi, M; Kuper, G; van Leeuwen, J; Maat, P; Mann, G; McKean, J P; Mevius, M; Mol, J D; Munk, H; Nijboer, R; Noordam, J E; Norden, M J; Orru, E; Paas, H; Pandey-Pommier, M; Pizzo, R; Polatidis, A G; Reich, W; Rottgering, H J A; Sluman, J; Smirnov, O; Stappers, B; Tagger, M; Tang, Y; Tasse, C; ter Veen, S; Vermeulen, R; van Weeren, R J; Wise, M; Wucknitz, O; Zarka, P

    2013-01-01

    The aim of the LOFAR Epoch of Reionization (EoR) project is to detect the spectral fluctuations of the redshifted HI 21cm signal. This signal is weaker by several orders of magnitude than the astrophysical foreground signals and hence, in order to achieve this, very long integrations, accurate calibration for stations and ionosphere and reliable foreground removal are essential. One of the prospective observing windows for the LOFAR EoR project will be centered at the North Celestial Pole (NCP). We present results from observations of the NCP window using the LOFAR highband antenna (HBA) array in the frequency range 115 MHz to 163 MHz. The data were obtained in April 2011 during the commissioning phase of LOFAR. We used baselines up to about 30 km. With about 3 nights, of 6 hours each, effective integration we have achieved a noise level of about 100 microJy/PSF in the NCP window. Close to the NCP, the noise level increases to about 180 microJy/PSF, mainly due to additional contamination from unsubtracted nea...

  5. A greedy-navigator approach to navigable city plans

    CERN Document Server

    Lee, Sang Hoon

    2012-01-01

    We use a set of four theoretical navigability indices for street maps to investigate the shape of the resulting street networks, if they are grown by optimizing these indices. The indices compare the performance of simulated navigators (having a partial information about the surroundings, like humans in many real situations) to the performance of optimally navigating individuals. We show that our simple greedy shortcut construction strategy generates the emerging structures that are different from real road network, but not inconceivable. The resulting city plans, for all navigation indices, share common qualitative properties such as the tendency for triangular blocks to appear, while the more quantitative features, such as degree distributions and clustering, are characteristically different depending on the type of metrics and routing strategies. We show that it is the type of metrics used which determines the overall shapes characterized by structural heterogeneity, but the routing schemes contribute to m...

  6. Navigable networks as Nash equilibria of navigation games

    Science.gov (United States)

    Gulyás, András; Bíró, József J.; Kőrösi, Attila; Rétvári, Gábor; Krioukov, Dmitri

    2015-07-01

    Common sense suggests that networks are not random mazes of purposeless connections, but that these connections are organized so that networks can perform their functions well. One function common to many networks is targeted transport or navigation. Here, using game theory, we show that minimalistic networks designed to maximize the navigation efficiency at minimal cost share basic structural properties with real networks. These idealistic networks are Nash equilibria of a network construction game whose purpose is to find an optimal trade-off between the network cost and navigability. We show that these skeletons are present in the Internet, metabolic, English word, US airport, Hungarian road networks, and in a structural network of the human brain. The knowledge of these skeletons allows one to identify the minimal number of edges, by altering which one can efficiently improve or paralyse navigation in the network.

  7. Kepler-47 Circumbinary Planets obey Quantization of Angular Momentum per Unit Mass predicted by Quantum Celestial Mechanics (QCM

    Directory of Open Access Journals (Sweden)

    Potter F.

    2014-01-01

    Full Text Available The Kepler-47 circumbinary system has three known planets orbiting its binary star barycenter and therefore can provide a precision test of the Quantum Celestial Mechan- ics (QCM prediction of the quantization of angular momentum per unit mass in all gravitationally bound systems. Two of the planets are in the Habitable Zone (HZ, so system stability can be a primary concern. QCM may be a major contributor to the stability of this system.

  8. Navigation in Augmented Reality, Navigation i Augmented Reality

    OpenAIRE

    Bernelind, Sarah

    2015-01-01

    The concept of augmented reality has existed since the 60’s. In this thesis it has been investigated if navigation using a mobile device would benefit, from a usability perspective, if the navigational data were presented using augmented reality instead of a standardized map. The usability principles from which the applications were evaluated are learnability, user satisfaction, efficiency and effectivity. An AR prototype was developed and tested against a standard map, in the form of Google ...

  9. Radio Navigation Waveform Experiment Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA is installing the Communications, Navigation, and Networking reConfigurable Testbed (CoNNeCT) onto the truss of the International Space Station to demonstrate...

  10. NOAA Electronic Navigational Charts (ENC)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of Coast Survey (OCS) has been involved in the development of a NOAA Electronic Navigational Chart (NOAA ENC) suite to support the marine transportation...

  11. 天文导航中的星敏感器技术%Key techniques of star sensors for celestial navigation

    Institute of Scientific and Technical Information of China (English)

    李葆华; 刘国良; 刘睿; 王常虹

    2009-01-01

    由于星敏感器仅仅工作在全天球的识别模式下远不能满足当前飞行器任务的需要,提出了当星敏感器有足够的先验信息情况下,可在星跟踪模式或者预测星像模式下工作,来提高星敏感器的数据更新率,降低由全天球识别带来误匹配的可能性.本文提出了一种新的星跟踪算法来克服飞行器在大角速度飞行情况下传统星跟踪算法处理时间过长等不足;为了消除由于系统噪声带来的误差,还提出了星图滤波和星像滤波的方法.实验结果表明,当飞行器在2.25°/s的角速度下飞行时,星敏感器能在10 pixel×10 pixel的范围内从星图中正确提取星像,星图经去噪后,星敏感器输出精度提高了近5″,从而使星敏器可在飞行器高动态飞行情况下实现高精度、高更新率的姿态输出.文中描述的所有方法已在2007年和2008年进行了地面观星测试,并于2009年即将应用于某些卫星的姿控系统中.%Star sensors may work in star tracking cases and predictive centroiding algorithm cases when it has sufficient attitude knowledge, which not only can increase the update rates of star sensors, but also can improve recognition performance. A novel star tracking algorithm for a star sensor with a large angle manoeuver is presented to avoid disadvantages of classic star tracking algorithms. In order to decrease noise errors of the star sensor, the filtering algorithms for star images and star locations are presented. The experimental results show that the star locations are obtained in the threshold scan window 10 pixel×10 pixel in the star image and the attitude accuracy of the star sensor is improved by 5″ in the star image filtered by C-L wavelet, when the spacecrafts are rolled with a angle velocity of 2.25°/s. These algorithms are tested at night sky experiments in 2007 and in 2008 and will be used in the attitude control system of a satellite in 2009.

  12. The lizard celestial compass detects linearly polarized light in the blue.

    Science.gov (United States)

    Beltrami, Giulia; Parretta, Antonio; Petrucci, Ferruccio; Buttini, Paola; Bertolucci, Cristiano; Foà, Augusto

    2012-09-15

    The present study first examined whether ruin lizards, Podarcis sicula, are able to orientate using plane-polarized light produced by an LCD screen. Ruin lizards were trained and tested indoors, inside a hexagonal Morris water maze positioned under an LCD screen producing white polarized light with a single E-vector, which provided an axial cue. White polarized light did not include wavelengths in the UV. Lizards orientated correctly either when tested with E-vector parallel to the training axis or after 90 deg rotation of the E-vector direction, thus validating the apparatus. Further experiments examined whether there is a preferential region of the light spectrum to perceive the E-vector direction of polarized light. For this purpose, lizards reaching learning criteria under white polarized light were subdivided into four experimental groups. Each group was tested for orientation under a different spectrum of plane-polarized light (red, green, cyan and blue) with equalized photon flux density. Lizards tested under blue polarized light orientated correctly, whereas lizards tested under red polarized light were completely disoriented. Green polarized light was barely discernible by lizards, and thus insufficient for a correct functioning of their compass. When exposed to cyan polarized light, lizard orientation performances were optimal, indistinguishable from lizards detecting blue polarized light. Overall, the present results demonstrate that perception of linear polarization in the blue is necessary - and sufficient - for a proper functioning of the sky polarization compass of ruin lizards. This may be adaptively important, as detection of polarized light in the blue improves functioning of the polarization compass under cloudy skies, i.e. when the alternative celestial compass based on detection of the sun disk is rendered useless because the sun is obscured by clouds.

  13. On the consistency of the current conventional EOP series and the celestial and terrestrial reference frames

    Science.gov (United States)

    Belda, Santiago; Heinkelmann, Robert; Ferrándiz, José M.; Nilsson, Tobias; Schuh, Harald

    2017-02-01

    Precise transformation between the celestial reference frames (CRF) and terrestrial reference frames (TRF) is needed for many purposes in Earth and space sciences. According to the Global Geodetic Observing System (GGOS) recommendations, the accuracy of positions and stability of reference frames should reach 1 mm and 0.1 mm year^{-1}, and thus, the Earth Orientation Parameters (EOP) should be estimated with similar accuracy. Different realizations of TRFs, based on the combination of solutions from four different space geodetic techniques, and CRFs, based on a single technique only (VLBI, Very Long Baseline Interferometry), might cause a slow degradation of the consistency among EOP, CRFs, and TRFs (e.g., because of differences in geometry, orientation and scale) and a misalignment of the current conventional EOP series, IERS 08 C04. We empirically assess the consistency among the conventional reference frames and EOP by analyzing the record of VLBI sessions since 1990 with varied settings to reflect the impact of changing frames or other processing strategies on the EOP estimates. Our tests show that the EOP estimates are insensitive to CRF changes, but sensitive to TRF variations and unmodeled geophysical signals at the GGOS level. The differences between the conventional IERS 08 C04 and other EOP series computed with distinct TRF settings exhibit biases and even non-negligible trends in the cases where no differential rotations should appear, e.g., a drift of about 20 μ as year^{-1 }in y_{pol } when the VLBI-only frame VTRF2008 is used. Likewise, different strategies on station position modeling originate scatters larger than 150 μ as in the terrestrial pole coordinates.

  14. Non-parametric PSF estimation from celestial transit solar images using blind deconvolution

    Science.gov (United States)

    González, Adriana; Delouille, Véronique; Jacques, Laurent

    2016-01-01

    Context: Characterization of instrumental effects in astronomical imaging is important in order to extract accurate physical information from the observations. The measured image in a real optical instrument is usually represented by the convolution of an ideal image with a Point Spread Function (PSF). Additionally, the image acquisition process is also contaminated by other sources of noise (read-out, photon-counting). The problem of estimating both the PSF and a denoised image is called blind deconvolution and is ill-posed. Aims: We propose a blind deconvolution scheme that relies on image regularization. Contrarily to most methods presented in the literature, our method does not assume a parametric model of the PSF and can thus be applied to any telescope. Methods: Our scheme uses a wavelet analysis prior model on the image and weak assumptions on the PSF. We use observations from a celestial transit, where the occulting body can be assumed to be a black disk. These constraints allow us to retain meaningful solutions for the filter and the image, eliminating trivial, translated, and interchanged solutions. Under an additive Gaussian noise assumption, they also enforce noise canceling and avoid reconstruction artifacts by promoting the whiteness of the residual between the blurred observations and the cleaned data. Results: Our method is applied to synthetic and experimental data. The PSF is estimated for the SECCHI/EUVI instrument using the 2007 Lunar transit, and for SDO/AIA using the 2012 Venus transit. Results show that the proposed non-parametric blind deconvolution method is able to estimate the core of the PSF with a similar quality to parametric methods proposed in the literature. We also show that, if these parametric estimations are incorporated in the acquisition model, the resulting PSF outperforms both the parametric and non-parametric methods.

  15. On the Analysis of Multistep-Out-of-Grid Method for Celestial Mechanics Tasks

    Science.gov (United States)

    Olifer, L.; Choliy, V.

    2016-09-01

    Occasionally, there is a necessity in high-accurate prediction of celestial body trajectory. The most common way to do that is to solve Kepler's equation analytically or to use Runge-Kutta or Adams integrators to solve equation of motion numerically. For low-orbit satellites, there is a critical need in accounting geopotential and another forces which influence motion. As the result, the right side of equation of motion becomes much bigger, and classical integrators will not be quite effective. On the other hand, there is a multistep-out-of-grid (MOG) method which combines Runge-Kutta and Adams methods. The MOG method is based on using m on-grid values of the solution and n × m off-grid derivative estimations. Such method could provide stable integrators of maximum possible order, O (hm+mn+n-1). The main subject of this research was to implement and analyze the MOG method for solving satellite equation of motion with taking into account Earth geopotential model (ex. EGM2008 (Pavlis at al., 2008)) and with possibility to add other perturbations such as atmospheric drag or solar radiation pressure. Simulations were made for satellites on low orbit and with various eccentricities (from 0.1 to 0.9). Results of the MOG integrator were compared with results of Runge-Kutta and Adams integrators. It was shown that the MOG method has better accuracy than classical ones of the same order and less right-hand value estimations when is working on high orders. That gives it some advantage over "classical" methods.

  16. Joint analysis of celestial pole offset and free core nutation series

    Science.gov (United States)

    Malkin, Zinovy

    2016-10-01

    Three combined celestial pole offset (CPO) series computed at the Paris Observatory (C04), the United States Naval Observatory (USNO), and the International VLBI Service for Geodesy and Astrometry (IVS), as well as six free core nutation (FCN) models, were compared from different perspectives, such as stochastic and systematic differences, and FCN amplitude and phase variations. The differences between the C04 and IVS CPO series were mostly stochastic, whereas a low-frequency bias at the level of several tens of μ as was found between the C04 and USNO CPO series. The stochastic differences between the C04 and USNO series became considerably smaller when computed at the IVS epochs, which can indicate possible problems with the interpolation of the IVS data at the midnight epochs during the computation of the C04 and USNO series. The comparison of the FCN series showed that the series computed with similar window widths of 1.1-1.2 years were close to one another at a level of 10-20 μ as, whereas the differences between these series and the series computed with a larger window width of 4 and 7 years reached 100 μ as. The dependence of the FCN model on the underlying CPO series was investigated. The RMS differences between the FCN models derived from the C04, USNO, and IVS CPO series were at a level of approximately 15 μ as, which was considerably smaller than the differences among the CPO series. The analysis of the differences between the IVS, C04, and USNO CPO series suggested that the IVS series would be preferable for both precession-nutation and FCN-related studies.

  17. On the consistency of the current conventional EOP series and the celestial and terrestrial reference frames

    Science.gov (United States)

    Belda, Santiago; Heinkelmann, Robert; Ferrándiz, José M.; Nilsson, Tobias; Schuh, Harald

    2016-08-01

    Precise transformation between the celestial reference frames (CRF) and terrestrial reference frames (TRF) is needed for many purposes in Earth and space sciences. According to the Global Geodetic Observing System (GGOS) recommendations, the accuracy of positions and stability of reference frames should reach 1 mm and 0.1 mm year^{-1} , and thus, the Earth Orientation Parameters (EOP) should be estimated with similar accuracy. Different realizations of TRFs, based on the combination of solutions from four different space geodetic techniques, and CRFs, based on a single technique only (VLBI, Very Long Baseline Interferometry), might cause a slow degradation of the consistency among EOP, CRFs, and TRFs (e.g., because of differences in geometry, orientation and scale) and a misalignment of the current conventional EOP series, IERS 08 C04. We empirically assess the consistency among the conventional reference frames and EOP by analyzing the record of VLBI sessions since 1990 with varied settings to reflect the impact of changing frames or other processing strategies on the EOP estimates. Our tests show that the EOP estimates are insensitive to CRF changes, but sensitive to TRF variations and unmodeled geophysical signals at the GGOS level. The differences between the conventional IERS 08 C04 and other EOP series computed with distinct TRF settings exhibit biases and even non-negligible trends in the cases where no differential rotations should appear, e.g., a drift of about 20 μ as year^{-1 } in y_{pol } when the VLBI-only frame VTRF2008 is used. Likewise, different strategies on station position modeling originate scatters larger than 150 μ as in the terrestrial pole coordinates.

  18. 33 CFR 401.54 - Interference with navigation aids.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Interference with navigation aids. 401.54 Section 401.54 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION... with navigation aids. (a) Aids to navigation shall not be interfered with or used as moorings. (b)...

  19. 33 CFR 100.45 - Establishment of aids to navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Establishment of aids to navigation. 100.45 Section 100.45 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND... navigation. The District Commander will establish and maintain only those aids to navigation necessary...

  20. 33 CFR 67.35-10 - Private aids to navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Private aids to navigation. 67.35-10 Section 67.35-10 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Applications §...

  1. 33 CFR 207.275 - McClellan-Kerr Arkansas River navigation system: use, administration, and navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false McClellan-Kerr Arkansas River navigation system: use, administration, and navigation. 207.275 Section 207.275 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS §...

  2. Global navigation satellite systems, inertial navigation, and integration

    CERN Document Server

    Grewal, Mohinder S; Bartone, Chris G

    2013-01-01

    An updated guide to GNSS, and INS, and solutions to real-world GNSS/INS problems with Kalman filtering Written by recognized authorities in the field, this third edition of a landmark work provides engineers, computer scientists, and others with a working familiarity of the theory and contemporary applications of Global Navigation Satellite Systems (GNSS), Inertial Navigational Systems, and Kalman filters. Throughout, the focus is on solving real-world problems, with an emphasis on the effective use of state-of-the-art integration techniques for those systems, especially the application of Kal

  3. 空天飞行器SINS/CNS深组合导航算法%SINS/CNS tightly integrated navigation algorithm for aerospace vehicles

    Institute of Scientific and Technical Information of China (English)

    杨淑洁; 杨功流; 单友东; 王艳永; 朱占龙

    2013-01-01

    空天飞行器往返于大气层内外,持续工作时间长。捷联惯性/天文组合导航自主性强、隐蔽性好,是最适合空天飞行器的导航方式之一。为提高传统天文定位的导航精度和可靠性,解决其在机载应用中水平基准制约的问题,分析了平台误差角和位置误差对高度角量测的影响,提出了一种以天体高度角为量测信息的捷联惯性/天文深组合导航算法。该算法采用卡尔曼滤波器进行最优估计,可有效估计并补偿系统的姿态误差,减少天文导航定位对水平基准的依赖。仿真表明,单星观测条件下,导航系统姿态误差快速收敛,定位的均方根误差在200 m以内,且系统导航性能随导航星数量的增加而提高。%Aerospace vehicles usually work both inside and outside the Earth’s atmosphere for long-range missions, and strap-down inertial navigation system (SINS) / celestial navigation system (CNS) integrated navigation method has been considered as an appropriate navigation solution for aerospace vehicles due to its autonomous and concealment capabilities. In order to overcome the limitation of horizontal reference in CNS and improve its accuracy and reliability, this paper analyzes the influence of platform error angles and positioning errors on altitude angle measurement, and proposes a novel algorithm for SINS/CNS tightly integrated navigation based on measured altitudes of celestial bodies. Kalman filter is utilized in this approach in order to effectively compensate attitude errors of SINS and reduce the dependence on horizon reference in CNS. Simulation result demonstrates that the convergence of attitude errors is rapid when single navigational star is observed, and the estimated root mean square positioning error (RMSE) is within 200 m. It also shows that more navigational stars will improve system navigation performance.

  4. Søgning og navigation

    DEFF Research Database (Denmark)

    Grauballe, Henning; Strunck, Kirsten Marie

    6 udvalgte testposter undersøges i 97 danske folkebibliotekers webkataloger med henblik på at afdække, hvordan disse testposters kontrollerede data udnyttes som hyperlinks til navigation og til videresøgning på ”Noget der ligner”. Undersøgelsen viser, at webkatalogerne især fokuserer på at udnytte...... opstillingsdata og udvalgte emnedata til navigation. Dermed udnyttes det samlede potentiale i de kontrollerede data ikke til at imødekomme brugernes forventninger til navigation ved hjælp af hyperlinks på Web’en. Undersøgelsen indikerer desuden, at der er en tæt sammenhæng mellem det konkrete bibliotekssystem...

  5. Mechanisms of Earth activity forsed by external celestial bodies:energy budjet and nature of cyclicity

    Science.gov (United States)

    Barkin, Yu. V.; Ferrandiz, J. M.

    2003-04-01

    In given report we discuss tidal and non-tidal mechanisms of forced tectonic (endogenous) activity of the Earth caused by gravitational attraction of the Moon, Sun and the planets. On the base of the classical solution of the problem of elasticity for model of the Earth with concentric mass distribution the evaluations of the tidal energy and power of Earth lunar-solar deformations, including their joint effect, were obtained. Important role of the joint energetic effect of rotational deformation of the Earth with lunar and solar tides was illustrated. Gravitational interaction of the Moon and Sun with non-spherical, non-homogeneous shells of the Earth generates big additional mechanical forces and moments of the interaction of the neighboring shells (rigid core, liquid core, mantle, lithosphere and separate plates). Acting of these forces and moments in the different time scales on the corresponding sells generates cyclic perturbations of the tensional state of the shells, their deformations, small relative translational displacements and small relative rotational oscillations of the shells. In geological period of time it leads to a fundamental tectonic reconstruction of the Earth. These additional forces and moments of the cyclic celestial-mechanical nature produce cyclic deformations of the all layers of the body and organize and control practically all natural processes. The additional force between mantle and core is cyclic and characterized by the wide basis of frequencies typical for orbital motions (of the Sun, Moon and planets), for rotational motion of the Earth, Moon and Sun and for many from observed natural processes. The problem about small relative translatory-rotary motion of the two shells separated by the thin viscous-elastic layer is studied. The differential equations of motion were obtained and have been studied in particular cases (plane motion of system; case of two axisymmetrical interacting shells and oth.) by approximate methods of small

  6. Gaia, Helios, Selene and Ouranos: the three principal celestial bodies and the sky in the ancient Greek cosmogony

    Science.gov (United States)

    Theodossiou, Efstratios; Manimanis, Vassilios N.; Dimitrijević, Milan S.; Mantarakis, Petros

    In this article we consider the role of the three principal celestial bodies, the Earth (Gaia), the Sun (Helios) and the Moon (Selene), as well as the Sky (Ouranos) in the ancient Greek cosmogony. This is done by the analysis of antique Greek texts like Orphic Hymns and the literary remains of the writers and philosophers like Aeschylus, (Pseudo) Apollodorus, Apollonius Rhodius, Aristotle, Euripides, Hesiod, Homer, Hyginus, Nonnus, Pausanias, Pindar and Sophocles, as well as by the analysis of texts of Roman writers like Cicero, Ovid and Pliny.

  7. Quantum and Post-Newtonian Effects in the Anomalistic Period and the Mean Motion of Celestial Bodies

    CERN Document Server

    Haranas, Ioannis; Gkigkitzis, Ioannis; Kotsireas, Ilias

    2015-01-01

    We study the motion of a secondary celestial body under the influence of the corrected gravitational force of a primary. We study the effect of quantum and relativistic corrections to the gravitational potential of a primary body acting on the orbiting body. More specifically, two equations are derived to approximate the perigee/perihelion/periastron time rate of change and its total variation over one revolution (i.e., the difference between the anomalistic period and the Keplerian period) under the influence of the quantum as well as post- Newtonian accelerations. Numerical results have been obtained for the artificial Earth satellite Molnya, Mercury, and, finally, the for the HW Vir c, planetary companion.

  8. Observability of Inertial Navigation System

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    To improve the observability of strapdown inertial navigation system and the effectiveness of Kalman filter in the navigation system, the method of estimating the observability is analyzed based on eigenvalues and eigenvectors which are proved to be availabe, on this basis two-position alignment technigue is applied. The simulation shows that two-position alignment really makes the system's observability change from being incomplete to being complete, and the test method based on eigenvalues and eigenvectors is available to determine the observability of every state vector.

  9. 27.3-day and Average 13.6-day Periodic Oscillations in the Earth's Rotation Rate and Atmospheric Pressure Fields Due to Celestial Gravitation Forcing

    Institute of Scientific and Technical Information of China (English)

    LI Guoqing; ZONG Haifeng; ZHANG Qingyun

    2011-01-01

    Variation in length of day of the Earth (LOD equivalent to the Earth's rotation rate) versus change in atmospheric geopotential height fields and astronomical parameters were analyzed for the years 1962-2006.This revealed that there is a 27.3-day and an average 13.6-day periodic oscillation in LOD and atmospheric pressure fields following lunar revolution around the Earth. Accompanying the alternating change in celestial gravitation forcing on the Earth and its atmosphere, the Earth's LOD changes from minimum to maximum,then to minimum. and the atmospheric geopotential height fields in the tropics oscillate from low to high,then to low. The 27.3-day and average 13.6-day periodic atmospheric oscillation in the tropics is proposed to be a type of strong atmospheric tide, excited by celestial gravitation forcing. A formula for a Tidal Index was derived to estimate the strength of the celestial gravitation forcing, and a high degree of correlation was found between the Tidal Index determined by astronomical parameters, LOD, and atmospheric geopotential height. The reason for the atmospheric tide is periodic departure of the lunar orbit from the celestial equator during lunar revolution around the Earth. The alternating asymmetric change in celestial gravitation forcing on the Earth and its atmosphere produces a "modulation" to the change in the Earth's LOD and atmospheric pressure fields.

  10. Navigation in Cross-cultural business relationships

    DEFF Research Database (Denmark)

    Andersen, Poul Houman

    2001-01-01

    Cross-cultural business navigation concerns the process of handling the complexity of several interacting cultural spheres of influence......Cross-cultural business navigation concerns the process of handling the complexity of several interacting cultural spheres of influence...

  11. Improved navigation for image-guided bronchoscopy

    Science.gov (United States)

    Khare, Rahul; Yu, Kun-Chang; Higgins, William E.

    2009-02-01

    Past work has shown that guidance systems help improve both the navigation through airways and final biopsy of regions of interest via bronchoscopy. We have previously proposed an image-based bronchoscopic guidance system. The system, however, has three issues that arise during navigation: 1) sudden disorienting changes can occur in endoluminal views; 2) more feedback could be afforded during navigation; and 3) the system's graphical user interface (GUI) lacks a convenient interface for smooth navigation between bifurcations. In order to alleviate these issues, we present an improved navigation system. The improvements offer the following: 1) an enhanced visual presentation; 2) smooth navigation; 3) an interface for handling registration errors; and 4) improved bifurcation-point identification. The improved navigation system thus provides significant ergonomic and navigational advantages over the previous system.

  12. Generating navigation models from existing building data

    NARCIS (Netherlands)

    Liu, L.; Zlatanova, S.

    2013-01-01

    Research on indoor navigation models mainly focuses on geometric and logical models .The models are enriched with specific semantic information which supports localisation, navigation and guidance. Geometric models provide information about the structural (physical) distribution of spaces in a build

  13. Honeybees as a model for the study of visually guided flight, navigation, and biologically inspired robotics.

    Science.gov (United States)

    Srinivasan, Mandyam V

    2011-04-01

    Research over the past century has revealed the impressive capacities of the honeybee, Apis mellifera, in relation to visual perception, flight guidance, navigation, and learning and memory. These observations, coupled with the relative ease with which these creatures can be trained, and the relative simplicity of their nervous systems, have made honeybees an attractive model in which to pursue general principles of sensorimotor function in a variety of contexts, many of which pertain not just to honeybees, but several other animal species, including humans. This review begins by describing the principles of visual guidance that underlie perception of the world in three dimensions, obstacle avoidance, control of flight speed, and orchestrating smooth landings. We then consider how navigation over long distances is accomplished, with particular reference to how bees use information from the celestial compass to determine their flight bearing, and information from the movement of the environment in their eyes to gauge how far they have flown. Finally, we illustrate how some of the principles gleaned from these studies are now being used to design novel, biologically inspired algorithms for the guidance of unmanned aerial vehicles.

  14. Mobile Robot Navigation Support in Living Environments

    Science.gov (United States)

    Armbrust, Christopher; Koch, Jan; Stocker, Ulf; Berns, Karsten

    Navigation and application functionality of mobile robots rely on their collision-avoiding capabilities, also known as local navigation. We present the mobile robot ARTOS (Autonomous Robot for Transport and Service) that is particularly designed to operate in living environments and therefore faces the problem of fuzzy and unstructured obstacles. The local navigation architecture is motivated regarding decisions on sensor hardware setup as well as the software layers that support and influence navigation control.

  15. Navigation Issues in the South China Sea

    OpenAIRE

    2005-01-01

    The South China Sea is one of the most important sea lanes with numerous competing sovereignty disputes. The freedom of navigation in this region is critical to all major trading States in the world. After an introduction to the navigational regimes of UNCLOS, this article describes the whole navigation situation in this region, by separately introducing the navigation issues in the territorial sea, straits, archipelagic waters and the Spratly area. Meanwhile, since the legal status of the ma...

  16. Surgical navigation with QR codes

    Directory of Open Access Journals (Sweden)

    Katanacho Manuel

    2016-09-01

    Full Text Available The presented work is an alternative to established measurement systems in surgical navigation. The system is based on camera based tracking of QR code markers. The application uses a single video camera, integrated in a surgical lamp, that captures the QR markers attached to surgical instruments and to the patient.

  17. Safety effects of navigation systems.

    NARCIS (Netherlands)

    2009-01-01

    Increasing numbers of drivers are using navigation systems in their cars. The advantages to the user are obvious: you can get to your destination via the fastest and shortest route. This reduces stress and exposure to other traffic. However, there are also some (unintended) negative effects. For exa

  18. Designing automated handheld navigation support

    NARCIS (Netherlands)

    Uluca, D.; Streefkerk, J.W.; Sciacchitano, B.; McCrickard, D.S.

    2008-01-01

    Map usage on handheld devices suffers from limited screen size and the minimal attention that users can dedicate to them in mobile situations. This work examines effects of automating navigation features like zooming and panning as well as other features such as rotation, path finding and artifact r

  19. 19 CFR 4.98 - Navigation fees.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Navigation fees. 4.98 Section 4.98 Customs Duties... VESSELS IN FOREIGN AND DOMESTIC TRADES General § 4.98 Navigation fees. (a)(1) The Customs Service shall... revised schedule of navigation fees for the following services: Fee No. and description of services...

  20. Lunar roving vehicle navigation system performance review

    Science.gov (United States)

    Smith, E. C.; Mastin, W. C.

    1973-01-01

    The design and operation of the lunar roving vehicle (LRV) navigation system are briefly described. The basis for the premission LRV navigation error analysis is explained and an example included. The real time mission support operations philosophy is presented. The LRV navigation system operation and accuracy during the lunar missions are evaluated.

  1. An analytical model for the celestial distribution of polarized light, accounting for polarization singularities, wavelength and atmospheric turbidity

    Science.gov (United States)

    Wang, Xin; Gao, Jun; Fan, Zhiguo; Roberts, Nicholas W.

    2016-06-01

    We present a computationally inexpensive analytical model for simulating celestial polarization patterns in variable conditions. We combine both the singularity theory of Berry et al (2004 New J. Phys. 6 162) and the intensity model of Perez et al (1993 Sol. Energy 50 235-245) such that our single model describes three key sets of data: (1) the overhead distribution of the degree of polarization as well as the existence of neutral points in the sky; (2) the change in sky polarization as a function of the turbidity of the atmosphere; and (3) sky polarization patterns as a function of wavelength, calculated in this work from the ultra-violet to the near infra-red. To verify the performance of our model we generate accurate reference data using a numerical radiative transfer model and statistical comparisons between these two methods demonstrate no significant difference in almost all situations. The development of our analytical model provides a novel method for efficiently calculating the overhead skylight polarization pattern. This provides a new tool of particular relevance for our understanding of animals that use the celestial polarization pattern as a source of visual information.

  2. Actual Problems in Celestial Mechanics and Dynamical Astronomy, International Conference Cluj/Napoca, Romania, May 25-27, 2006

    Science.gov (United States)

    Érdi, B.; Szenkovits, F.

    2007-05-01

    In 25--27 May 2006 an International Conference on Actual Problems in Celestial Mechanics and Dynamical Astronomy was organized at Cluj-Napoca. The Faculty of Mathematics and Computer Science of the Babeş-Bolyai University, the host of this conference, organized this scientific meeting in collaboration with the Loránd Eötvös University (Budapest, Hungary), Sapientia University (Miercuria Ciuc, Romania), Astronomical Institute of the Romanian Academy (Bucharest, Romania) and Institute for Space Science (Bucharest, Romania). The main topics covered by the meeting were: - Solar-System dynamics, stability, resonances, chaos; - Dynamics of populations in the Solar System: NEAs, MBAs, Centaurs, KBOs, TNOs: observations, orbits, theoretical models; - Galactic and extragalactic dynamics; - Problems, models, methods and techniques in contemporary celestial mechanics and dynamical astronomy. The conference was structured into seven sessions of oral presentations, a poster session and a round table discussion. Each of the seven main sessions began with an invited lecture. These lectures reviewed the following fields: the Sitnikov problem (R. Dvorak, Austria); the age of the asteroid families (Z. Knezevic, Serbia and Montenegro); stability of exoplanetary systems (B. Érdi, Hungary); Saari's conjecture (Diacu, Canada); integrability from direct and inverse standpoints (G. Bozis, Greece); stability of exact solutions in restricted many-body problems (E. Grebenicov, Russia); actual Romanian research in post-Newtonian dynamics (V. Mioc, Romania). Beside the invited lectures, the 21 oral presentations covered the most various domains of celestial mechanics and dynamical astronomy. Chaotic behaviour was a premier topic. It was approached and studied by analytical, geometrical and numerical methods in many astronomical problems: the restricted three-body problem (with examples in the Solar System), the Gylden's model and its generalizations, capture domain, resonances, etc

  3. 33 CFR 117.455 - Houma Navigation Canal.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Houma Navigation Canal. 117.455 Section 117.455 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Louisiana § 117.455 Houma Navigation Canal. The draw of SR 661 (Houma Nav Canal) bridge,...

  4. 33 CFR 401.97 - Closing procedures and ice navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Closing procedures and ice navigation. 401.97 Section 401.97 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Navigation...

  5. 33 CFR 207.306 - Missouri River; administration and navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Missouri River; administration and navigation. 207.306 Section 207.306 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS § 207.306 Missouri River;...

  6. 33 CFR 64.31 - Determination of hazard to navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Determination of hazard to navigation. 64.31 Section 64.31 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION MARKING OF STRUCTURES, SUNKEN VESSELS AND OTHER OBSTRUCTIONS...

  7. 33 CFR 162.240 - Tongass Narrows, Alaska; navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Tongass Narrows, Alaska; navigation. 162.240 Section 162.240 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY INLAND WATERWAYS NAVIGATION REGULATIONS § 162.240...

  8. Introduction on background medium theory about celestial body motion orbit and foundation of fractional-dimension calculus about self-similar fractal measure calculation

    Science.gov (United States)

    Yan, Kun

    2007-04-01

    In this paper, by discussing the basic hypotheses about the continuous orbit and discrete orbit in two research directions of the background medium theory for celestial body motion, the concrete equation forms and their summary of the theoretic frame of celestial body motion are introduced. Future more, by discussing the general form of Binet's equation of celestial body motion orbit and it's solution of the advance of the perihelion of planets, the relations and differences between the continuous orbit theory and Newton's gravitation theory and Einstein's general relativity are given. And by discussing the fractional-dimension expanded equation for the celestial body motion orbits, the concrete equations and the prophesy data of discrete orbit or stable orbits of celestial bodies which included the planets in the Solar system, satellites in the Uranian system, satellites in the Earth system and satellites obtaining the Moon obtaining from discrete orbit theory are given too. Especially, as the preliminary exploration and inference to the gravitation curve of celestial bodies in broadly range, the concept for the ideal black hole with trend to infinite in mass density difficult to be formed by gravitation only is explored. By discussing the position hypothesis of fractional-dimension derivative about general function and the formula form the hypothesis of fractional-dimension derivative about power function, the concrete equation formulas of fractional-dimension derivative, differential and integral are described distinctly further, and the difference between the fractional-dimension derivative and the fractional-order derivative are given too. Subsequently, the concrete forms of measure calculation equations of self-similar fractal obtaining by based on the definition of form in fractional-dimension calculus about general fractal measure are discussed again, and the differences with Hausdorff measure method or the covering method at present are given. By applying

  9. A robust data fusion scheme for integrated navigation systems employing fault detection methodology augmented with fuzzy adaptive filtering

    Science.gov (United States)

    Ushaq, Muhammad; Fang, Jiancheng

    2013-10-01

    Integrated navigation systems for various applications, generally employs the centralized Kalman filter (CKF) wherein all measured sensor data are communicated to a single central Kalman filter. The advantage of CKF is that there is a minimal loss of information and high precision under benign conditions. But CKF may suffer computational overloading, and poor fault tolerance. The alternative is the federated Kalman filter (FKF) wherein the local estimates can deliver optimal or suboptimal state estimate as per certain information fusion criterion. FKF has enhanced throughput and multiple level fault detection capability. The Standard CKF or FKF require that the system noise and the measurement noise are zero-mean and Gaussian. Moreover it is assumed that covariance of system and measurement noises remain constant. But if the theoretical and actual statistical features employed in Kalman filter are not compatible, the Kalman filter does not render satisfactory solutions and divergence problems also occur. To resolve such problems, in this paper, an adaptive Kalman filter scheme strengthened with fuzzy inference system (FIS) is employed to adapt the statistical features of contributing sensors, online, in the light of real system dynamics and varying measurement noises. The excessive faults are detected and isolated by employing Chi Square test method. As a case study, the presented scheme has been implemented on Strapdown Inertial Navigation System (SINS) integrated with the Celestial Navigation System (CNS), GPS and Doppler radar using FKF. Collectively the overall system can be termed as SINS/CNS/GPS/Doppler integrated navigation system. The simulation results have validated the effectiveness of the presented scheme with significantly enhanced precision, reliability and fault tolerance. Effectiveness of the scheme has been tested against simulated abnormal errors/noises during different time segments of flight. It is believed that the presented scheme can be

  10. 33 CFR 207.169 - Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Oklawaha River, navigation lock and dam at Moss Bluff, Fla.; use, administration, and navigation. 207.169 Section 207.169 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE...

  11. Spatial navigation in young versus older adults

    Directory of Open Access Journals (Sweden)

    Ivana eGazova

    2013-12-01

    Full Text Available Older age is associated with changes in the brain, including the medial temporal lobe, which may result in mild spatial navigation deficits, especially in allocentric navigation. The aim of the study was to characterize the profile of real-space allocentric (world-centered, hippocampus dependent and egocentric (body-centered, parietal lobe dependent navigation and learning in young vs. older adults, and to assess a possible influence of gender. We recruited healthy participants without cognitive deficits on standard neuropsychological testing, white matter lesions or pronounced hippocampal atrophy: 24 young participants (18-26 years old and 44 older participants stratified as participants 60-70 years old (n=24 and participants 71-84 years old (n=20. All underwent spatial navigation testing in the real-space human analog of the Morris Water Maze, which has the advantage of assessing separately allocentric and egocentric navigation and learning. Of the 8 consecutive trials, trials 2-8 were used to reduce bias by a rebound effect (more dramatic changes in performance between trials 1 and 2 relative to subsequent trials. The participants who were 71-84 years old (p< .001, but not those 60-70 years old, showed deficit in allocentric navigation compared to the young participants. There were no differences in egocentric navigation. All three groups showed spatial learning effect (p´s ≤.01. There were no gender differences in spatial navigation and learning. The linear regression limited to older participants showed linear (β=0.30, p=.045 and quadratic (β=0.30, p=.046 effect of age on allocentric navigation. There was no effect of age on egocentric navigation. These results demonstrate that navigation deficits in older age may be limited to allocentric navigation, whereas egocentric navigation and learning may remain preserved. This specific pattern of spatial navigation impairment may help differentiate normal aging from prodromal Alzheimer

  12. Autonomous Guidance, Navigation and Control

    Science.gov (United States)

    Bordano, A. J.; Mcswain, G. G.; Fernandes, S. T.

    1991-01-01

    The NASA Autonomous Guidance, Navigation and Control (GN&C) Bridging program is reviewed to demonstrate the program plan and GN&C systems for the Space Shuttle. The ascent CN&C system is described in terms of elements such as the general-purpose digital computers, sensors for the navigation subsystem, the guidance-system software, and the flight-control subsystem. Balloon-based and lidar wind soundings are used for operations assessment on the day of launch, and the guidance software is based on dedicated units for atmospheric powered flight, vacuum powered flight, and abort-specific situations. Optimization of the flight trajectories is discussed, and flight-control responses are illustrated for wavelengths of 500-6000 m. Alternate sensors are used for load relief, and adaptive GN&C systems based on alternate gain synthesis are used for systems failures.

  13. 06421 Executive Summary -- Robot Navigation

    OpenAIRE

    Fekete, Sándor; Fleischer, Rudolf; Klein, Rolf; Lopez-Ortiz, Alejandro

    2007-01-01

    For quite a number of years, researchers from various fields have studied problems motivated by Robot Navigation. People in Online Algorithms have developed strategies that can deal with the inherent lack of information an autonomous robot encounters, as it sets out to perform a task in an unknown environment. Computational Geometers have obtained many results on the efficient planning of collision-free motions, and on visibility problems. Scientists and engineers in Robotics have perfected r...

  14. Orientation in birds. Olfactory navigation.

    Science.gov (United States)

    Papi, F

    1991-01-01

    Research work on the olfactory navigation of birds, which has only recently attracted attention, has shown that many wild species rely on an osmotactic mechanism to find food sources, even at a considerable distance. The homing pigeon, the only bird to have been thoroughly investigated with respect to olfactory navigation, has been found to rely on local odours for homeward orientation, and to integrate olfactory cues perceived during passive transportation with those picked up at the release site. It is possible to design experiments in which birds are given false olfactory information, and predictions about the effects of this can be made and tested. Pigeons are able to home from unfamiliar sites because they acquire an olfactory map extending beyond the area they have flown over. The olfactory map is built up by associating wind-borne odours with the direction from which they come; this was shown by experiments which aimed to prevent, limit or alter this association. One aim of the research work has been to test whether pigeons flying over unfamiliar areas also rely or can learn to rely on non-olfactory cues, depending on their local availability, and/or on the methods of rearing and training applied to them. Various evaluations have been made of the results; the most recent experiments, however, confirm that pigeons do derive directional information from atmospheric odours. A neurobiological approach is also in progress; its results show that some telencephalic areas are involved in orientation and olfactory navigation. The lack of any knowledge about the distribution and chemical nature of the odorants which allow pigeons to navigate hinders progress in this area of research.

  15. On the trail of Vikings with polarized skylight: experimental study of the atmospheric optical prerequisites allowing polarimetric navigation by Viking seafarers.

    Science.gov (United States)

    Horváth, Gábor; Barta, András; Pomozi, István; Suhai, Bence; Hegedüs, Ramón; Akesson, Susanne; Meyer-Rochow, Benno; Wehner, Rüdiger

    2011-03-12

    Between AD 900 and AD 1200 Vikings, being able to navigate skillfully across the open sea, were the dominant seafarers of the North Atlantic. When the Sun was shining, geographical north could be determined with a special sundial. However, how the Vikings could have navigated in cloudy or foggy situations, when the Sun's disc was unusable, is still not fully known. A hypothesis was formulated in 1967, which suggested that under foggy or cloudy conditions, Vikings might have been able to determine the azimuth direction of the Sun with the help of skylight polarization, just like some insects. This hypothesis has been widely accepted and is regularly cited by researchers, even though an experimental basis, so far, has not been forthcoming. According to this theory, the Vikings could have determined the direction of the skylight polarization with the help of an enigmatic birefringent crystal, functioning as a linearly polarizing filter. Such a crystal is referred to as 'sunstone' in one of the Viking's sagas, but its exact nature is unknown. Although accepted by many, the hypothesis of polarimetric navigation by Vikings also has numerous sceptics. In this paper, we summarize the results of our own celestial polarization measurements and psychophysical laboratory experiments, in which we studied the atmospheric optical prerequisites of possible sky-polarimetric navigation in Tunisia, Finland, Hungary and the high Arctic.

  16. Performance Enhancement of a USV INS/CNS/DVL Integration Navigation System Based on an Adaptive Information Sharing Factor Federated Filter.

    Science.gov (United States)

    Wang, Qiuying; Cui, Xufei; Li, Yibing; Ye, Fang

    2017-02-03

    To improve the ability of autonomous navigation for Unmanned Surface Vehicles (USVs), multi-sensor integrated navigation based on Inertial Navigation System (INS), Celestial Navigation System (CNS) and Doppler Velocity Log (DVL) is proposed. The CNS position and the DVL velocity are introduced as the reference information to correct the INS divergence error. The autonomy of the integrated system based on INS/CNS/DVL is much better compared with the integration based on INS/GNSS alone. However, the accuracy of DVL velocity and CNS position are decreased by the measurement noise of DVL and bad weather, respectively. Hence, the INS divergence error cannot be estimated and corrected by the reference information. To resolve the problem, the Adaptive Information Sharing Factor Federated Filter (AISFF) is introduced to fuse data. The information sharing factor of the Federated Filter is adaptively adjusted to maintaining multiple component solutions usable as back-ups, which can improve the reliability of overall system. The effectiveness of this approach is demonstrated by simulation and experiment, the results show that for the INS/CNS/DVL integrated system, when the DVL velocity accuracy is decreased and the CNS cannot work under bad weather conditions, the INS/CNS/DVL integrated system can operate stably based on the AISFF method.

  17. Universal tectonic dichotomy of small celestial bodies expressed in their common convexo-concave shapes

    Science.gov (United States)

    Kochemasov, G. G.

    2008-09-01

    The wave planetology [1, 2, 3 & others] declares in its first theorem that all celestial bodies are dichotomous. This is a result of a warping action of the fundamental wave (wave 1 long 2πR where R is a body radius) that appears in any body due to its movement in non-round (elliptical, parabolic) keplerian orbits with periodically changing accelerations. Having a standing character and four crossing directions in rotating bodies (but all bodies rotate!) these waves inevitably press in one hemisphere and bulge out the opposite one tending to impose on a body convexo-concave shape. This shape is leveled out in larger bodies due to enhanced gravity but is clearly observed in smaller ones with diminished gravity. Still, in the larger bodies as, for an example, in Earth the tectonic dichotomy is expressed as an opposition of the subsided western Pacific hemisphere and the uplifted eastern continental hemisphere. At Mars even sharper dichotomy is in the north-south direction. Small bodies (normally less than 400-500 km across) notwithstanding their type (asteroids, comets, satellites), size and composition (stones, metals, ices) are flattened and bended by the fundamental wave. That is why all asteroids in the main asteroid belt have an oblong shape what was established rather long ago but never was properly explained. Now a number of small satellites is observed by Cassini spacecraft in the saturnian system that makes together with jovian and martian small satellites a representative group for comparisons. In the figures below are shown asteroids, satellites and a comet arranged in a row of increasing sizes. They all are flattened except the largest in the row Enceladus (505 km) and bended tending to acquire a convexo-concave shape. Asteroids: Itokawa (0.5 km long), Eros (33 km, PIA03111). Satellites: Calypso (22 km, PIA07633), Atlas (32 km, PIA08233), Prometheus (102 km, PIA08192), Hyperion (350 km, PIA06645), Enceladus (505 km, PIA08258, comet-like behaviour). Comet

  18. Navigation Operations for the Magnetospheric Multiscale Mission

    Science.gov (United States)

    Long, Anne; Farahmand, Mitra; Carpenter, Russell

    2015-01-01

    The Magnetospheric Multiscale (MMS) mission employs four identical spinning spacecraft flying in highly elliptical Earth orbits. These spacecraft will fly in a series of tetrahedral formations with separations of less than 10 km. MMS navigation operations use onboard navigation to satisfy the mission definitive orbit and time determination requirements and in addition to minimize operations cost and complexity. The onboard navigation subsystem consists of the Navigator GPS receiver with Goddard Enhanced Onboard Navigation System (GEONS) software, and an Ultra-Stable Oscillator. The four MMS spacecraft are operated from a single Mission Operations Center, which includes a Flight Dynamics Operations Area (FDOA) that supports MMS navigation operations, as well as maneuver planning, conjunction assessment and attitude ground operations. The System Manager component of the FDOA automates routine operations processes. The GEONS Ground Support System component of the FDOA provides the tools needed to support MMS navigation operations. This paper provides an overview of the MMS mission and associated navigation requirements and constraints and discusses MMS navigation operations and the associated MMS ground system components built to support navigation-related operations.

  19. The Discovery of the Regular Movements of Celestial Bodies and the Development of Monotheism in the Ancient Near East

    Science.gov (United States)

    Lanfranchi, G. B.

    2011-06-01

    For Ancient Mesopotamians, astronomical phenomena were signs signifying the gods' judgment on human behaviour. Mesopotamian scholars studied celestial phenomena for understanding the gods' will, and strongly developed astrology. From the 8th to the 6th century BC Assyrian and Babylonian astronomers achieved the ability to predict solar and lunar eclipses, and the planets' movements through mathematical calculations. Predictability of astral phenomena solicited the awareness that they are all regular, and that the universe is governed by an eternal, immutable order fixed at its very beginning. This finally favoured the idea that the cosmic order depended on the will of one god only, displacing polytheism in favour of monotheism; and astrology lost its religious importance as a mean to know the divine will.

  20. Zero initial partial derivatives of satellite orbits with respect to force parameters violate the physics of motion of celestial bodies

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Satellite orbits have been routinely used to produce models of the Earth’s gravity field. In connection with such productions, the partial derivatives of a satellite orbit with respect to the force parameters to be determined, namely, the unknown harmonic coefficients of the gravitational model, have been first computed by setting the initial values of partial derivatives to zero. In this note, we first design some simple mathematical examples to show that setting the initial values of partial derivatives to zero is generally erroneous mathematically. We then prove that it is prohibited physically. In other words, set-ting the initial values of partial derivatives to zero violates the physics of motion of celestial bodies.

  1. Zero initial partial derivatives of satellite orbits with respect to force parameters violate the physics of motion of celestial bodies

    Institute of Scientific and Technical Information of China (English)

    XU PeiLiang

    2009-01-01

    Satellite orbits have been routinely used to produce models of the Earth's gravity field. In connection with such productions, the partial derivatives of a satellite orbit with respect to the force parameters to be determined, namely, the unknown harmonic coefficients of the gravitational model, have been first computed by setting the initial values of partial derivatives to zero. In this note, we first design some simple mathematical examples to show that setting the initial values of partial derivatives to zero is generally erroneous mathematically. We then prove that it is prohibited physically. In other words, set-ting the initial values of partial derivatives to zero violates the physics of motion of celestial bodies.

  2. The limit passage of space curvature in problems of celestial mechanics with the generalized Kepler and Hooke potentials

    Science.gov (United States)

    Vozmishcheva, Tatiana

    2016-09-01

    The connection between the problems of celestial mechanics: the Kepler problem, the two-center problem and the two body problem in spaces of constant curvature with the generalized Kepler and Hooke potentials is investigated. The limit passage in the two-center and two body problems in the Lobachevsky space and on a sphere is carried out as λto0 (λ is the curvature of the corresponding space) for the two potentials. The potentials and metrics in spaces under study are written in the gnomonic coordinates. It is shown that as the curvature radius tends to infinity, the generalized gravitational and elastic potentials transform to the Kepler and Hooke forms in the Euclidean space.

  3. Center of Mass of Two or More Celestial Bodies as a Basis of Comets and «Black Holes» Mechanism

    OpenAIRE

    Eugeny F. Orlov

    2012-01-01

    The article considers the questions, arising during rendezvous of two celestial bodies with equal mass, one of which is the Earth and the consequences of such rendezvous to modern civilization, suggests the idea of centers of galaxies mass with anomalously large values of the gravitational fields, which allows to divide them into two types – material filled and hollow.

  4. Center of Mass of Two or More Celestial Bodies as a Basis of Comets and «Black Holes» Mechanism

    Directory of Open Access Journals (Sweden)

    Eugeny F. Orlov

    2012-04-01

    Full Text Available The article considers the questions, arising during rendezvous of two celestial bodies with equal mass, one of which is the Earth and the consequences of such rendezvous to modern civilization, suggests the idea of centers of galaxies mass with anomalously large values of the gravitational fields, which allows to divide them into two types – material filled and hollow.

  5. Station Explorer X-Ray Timing and Navigation (SEXTANT) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Because of their predictable pulsations, pulsars are highly reliable celestial clocks that can provide the same high-precision timing as the atomic clock signals...

  6. Quantum Navigation and Ranking in Complex Networks

    Science.gov (United States)

    Sánchez-Burillo, Eduardo; Duch, Jordi; Gómez-Gardeñes, Jesús; Zueco, David

    2012-08-01

    Complex networks are formal frameworks capturing the interdependencies between the elements of large systems and databases. This formalism allows to use network navigation methods to rank the importance that each constituent has on the global organization of the system. A key example is Pagerank navigation which is at the core of the most used search engine of the World Wide Web. Inspired in this classical algorithm, we define a quantum navigation method providing a unique ranking of the elements of a network. We analyze the convergence of quantum navigation to the stationary rank of networks and show that quantumness decreases the number of navigation steps before convergence. In addition, we show that quantum navigation allows to solve degeneracies found in classical ranks. By implementing the quantum algorithm in real networks, we confirm these improvements and show that quantum coherence unveils new hierarchical features about the global organization of complex systems.

  7. Fusion of Onboard Sensors for Better Navigation

    Directory of Open Access Journals (Sweden)

    Ravi Shankar

    2013-03-01

    Full Text Available This paper presents simulation results of navigation sensors such as integrated navigation system (INS, global navigation satellite system (GNSS and TACAN sensors onboard an aircraft to find the navigation solutions. Mathematical models for INS, GNSS (GPS satellite trajectories, GPS receiver and TACAN characteristics are simulated in Matlab. The INS simulation generates the output for position, velocity and attitude based on aerosond dynamic model. The GPS constellation is generated based on the YUMA almanac data. The GPS dilution of precession (DOP parameters are calculated and the best combination of four satellites (minimum PDOP is used for calculating the user position and velocity. The INS, GNSS, and TACAN solutions are integrated through loosely coupled extended Kalman filter for calculating the optimum navigation solution. The work is starting stone for providing aircraft based augmentation system for required navigation performance in terms of availability, accuracy, continuity and integrity.

  8. INS/CNS/GNSS integrated navigation technology

    CERN Document Server

    Quan, Wei; Gong, Xiaolin; Fang, Jiancheng

    2015-01-01

    This book not only introduces the principles of INS, CNS and GNSS, the related filters and semi-physical simulation, but also systematically discusses the key technologies needed for integrated navigations of INS/GNSS, INS/CNS, and INS/CNS/GNSS, respectively. INS/CNS/GNSS integrated navigation technology has established itself as an effective tool for precise positioning navigation, which can make full use of the complementary characteristics of different navigation sub-systems and greatly improve the accuracy and reliability of the integrated navigation system. The book offers a valuable reference guide for graduate students, engineers and researchers in the fields of navigation and its control. Dr. Wei Quan, Dr. Jianli Li, Dr. Xiaolin Gong and Dr. Jiancheng Fang are all researchers at the Beijing University of Aeronautics and Astronautics.

  9. Research on integrated navigation method for AUV

    Institute of Scientific and Technical Information of China (English)

    GUO Zhen; SUN Feng

    2005-01-01

    The principles of the SINS/DVL integrated navigation system are introduced, and the compass status accuracy is compared. When the heading is changed, the dead reckoning algorithm using the heading information of the SINS (Strapdown inertial navigation systems) and DVL (doppler velocity log) is adopted to substitute the SINS/DVL integrated system. The simulation results show that the method can improve the accuracy of integrated navigation system when AUV (autonomous underwater vehicle) is in motion.

  10. Reliable dynamic in-vehicle navigation

    OpenAIRE

    Kaparias, I.

    2008-01-01

    Having started off from luxury makes and models, in-vehicle navigation systems are now gradually spreading through the entire vehicle fleet, as drivers appreciate their usefulness. Increasingly sophisticated systems are being developed, having much more advanced functions than simple driving directions. This thesis presents a new approach for in-vehicle navigation, in which travel time reliability is incorporated in the route finding component of the navigation system. Based on historical tra...

  11. Vector database for vehicle road navigation

    OpenAIRE

    Kenda, Lian

    2007-01-01

    Vehicle navigation devices use vector cartographic view, which is designed as a vector database. Database creation begins by setting up a landscape model which includes all the graphical and descriptive data required for accurate vehicle navigation. This paper presents the creation of a database part called StreetConnect, which is used for road navigation. Data obtained using distinct specifications have been transformed into the format compatible with Garmin GPS devices. Data have been obtai...

  12. Global navigation satellite systems and their applications

    CERN Document Server

    Madry, Scott

    2015-01-01

    Dr. Madry, one of the world's leading experts in the field, provides in a condensed form a quick yet comprehensive overview of satellite navigation. This book concisely addresses the latest technology, the applications, the regulatory issues, and the strategic implications of satellite navigation systems. This assesses the strengths and weaknesses of satellite navigation networks and review of all the various national systems now being deployed and the motivation behind the proliferation of these systems.

  13. 75 FR 39632 - Regulated Navigation Area; Gulf Intracoastal Waterway, Inner Harbor Navigation Canal, Harvey...

    Science.gov (United States)

    2010-07-12

    ..., Inner Harbor Navigation Canal, Harvey Canal, Algiers Canal, New Orleans, LA; Correction ACTION: Interim... Navigation Canal, Harvey Canal, Algiers Canal, New Orleans, LA into the Code of Federal Regulations....

  14. Neural encoding of objects relevant for navigation and resting state correlations with navigational ability

    NARCIS (Netherlands)

    Wegman, J.B.T.; Janzen, G.

    2011-01-01

    Objects along a route can help us to successfully navigate through our surroundings. Previous neuroimaging research has shown that the parahippocampal gyrus (PHG) distinguishes between objects that were previously encountered at navigationally relevant locations (decision points) and irrelevant loca

  15. Emergency Navigation without an Infrastructure

    Directory of Open Access Journals (Sweden)

    Erol Gelenbe

    2014-08-01

    Full Text Available Emergency navigation systems for buildings and other built environments, such as sport arenas or shopping centres, typically rely on simple sensor networks to detect emergencies and, then, provide automatic signs to direct the evacuees. The major drawbacks of such static wireless sensor network (WSN-based emergency navigation systems are the very limited computing capacity, which makes adaptivity very difficult, and the restricted battery power, due to the low cost of sensor nodes for unattended operation. If static wireless sensor networks and cloud-computing can be integrated, then intensive computations that are needed to determine optimal evacuation routes in the presence of time-varying hazards can be offloaded to the cloud, but the disadvantages of limited battery life-time at the client side, as well as the high likelihood of system malfunction during an emergency still remain. By making use of the powerful sensing ability of smart phones, which are increasingly ubiquitous, this paper presents a cloud-enabled indoor emergency navigation framework to direct evacuees in a coordinated fashion and to improve the reliability and resilience for both communication and localization. By combining social potential fields (SPF and a cognitive packet network (CPN-based algorithm, evacuees are guided to exits in dynamic loose clusters. Rather than relying on a conventional telecommunications infrastructure, we suggest an ad hoc cognitive packet network (AHCPN-based protocol to adaptively search optimal communication routes between portable devices and the network egress nodes that provide access to cloud servers, in a manner that spares the remaining battery power of smart phones and minimizes the time latency. Experimental results through detailed simulations indicate that smart human motion and smart network management can increase the survival rate of evacuees and reduce the number of drained smart phones in an evacuation process.

  16. Youth Mobilisation as Social Navigation

    DEFF Research Database (Denmark)

    Vigh, Henrik Erdman

    2010-01-01

    This article sheds light on the mobilisation of young people into conflict. It argues that warfare constitutes a terrain of possibility for urban youth in Guinea‑Bissau, and shows how they navigate war as an event by tactically manoeuvring within the social ties and options that arise in such situations. Building on the Guinean Creole term of dubriagem, the article proposes the concept of social navigation...... as an analytical optic able to shed light on praxis in unstable environments. The concept of social navigation makes it possible to focus on the way we move within changing social environments. It is processuality squared, illuminating motion within motion. The article thus advocates an analysis of praxis that takes its point of departure in a Batesonian and intermorphological understanding of action in order to further our understanding of the acts of youth in conflict....

  17. Crew-Aided Autonomous Navigation

    Science.gov (United States)

    Holt, Greg N.

    2015-01-01

    A sextant provides manual capability to perform star/planet-limb sightings and offers a cheap, simple, robust backup navigation source for exploration missions independent from the ground. Sextant sightings from spacecraft were first exercised in Gemini and flew as the lost-communication backup for all Apollo missions. This study characterized error sources of navigation-grade sextants for feasibility of taking star and planetary limb sightings from inside a spacecraft. A series of similar studies was performed in the early/mid-1960s in preparation for Apollo missions. This study modernized and updated those findings in addition to showing feasibility using Linear Covariance analysis techniques. The human eyeball is a remarkable piece of optical equipment and provides many advantages over camera-based systems, including dynamic range and detail resolution. This technique utilizes those advantages and provides important autonomy to the crew in the event of lost communication with the ground. It can also provide confidence and verification of low-TRL automated onboard systems. The technique is extremely flexible and is not dependent on any particular vehicle type. The investigation involved procuring navigation-grade sextants and characterizing their performance under a variety of conditions encountered in exploration missions. The JSC optical sensor lab and Orion mockup were the primary testing locations. For the accuracy assessment, a group of test subjects took sextant readings on calibrated targets while instrument/operator precision was measured. The study demonstrated repeatability of star/planet-limb sightings with bias and standard deviation around 10 arcseconds, then used high-fidelity simulations to verify those accuracy levels met the needs for targeting mid-course maneuvers in preparation for Earth reen.

  18. Emergency navigation without an infrastructure.

    Science.gov (United States)

    Gelenbe, Erol; Bi, Huibo

    2014-08-18

    Emergency navigation systems for buildings and other built environments, such as sport arenas or shopping centres, typically rely on simple sensor networks to detect emergencies and, then, provide automatic signs to direct the evacuees. The major drawbacks of such static wireless sensor network (WSN)-based emergency navigation systems are the very limited computing capacity, which makes adaptivity very difficult, and the restricted battery power, due to the low cost of sensor nodes for unattended operation. If static wireless sensor networks and cloud-computing can be integrated, then intensive computations that are needed to determine optimal evacuation routes in the presence of time-varying hazards can be offloaded to the cloud, but the disadvantages of limited battery life-time at the client side, as well as the high likelihood of system malfunction during an emergency still remain. By making use of the powerful sensing ability of smart phones, which are increasingly ubiquitous, this paper presents a cloud-enabled indoor emergency navigation framework to direct evacuees in a coordinated fashion and to improve the reliability and resilience for both communication and localization. By combining social potential fields (SPF) and a cognitive packet network (CPN)-based algorithm, evacuees are guided to exits in dynamic loose clusters. Rather than relying on a conventional telecommunications infrastructure, we suggest an ad hoc cognitive packet network (AHCPN)-based protocol to adaptively search optimal communication routes between portable devices and the network egress nodes that provide access to cloud servers, in a manner that spares the remaining battery power of smart phones and minimizes the time latency. Experimental results through detailed simulations indicate that smart human motion and smart network management can increase the survival rate of evacuees and reduce the number of drained smart phones in an evacuation process.

  19. Robotics_MobileRobot Navigation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Robots and rovers exploring planets need to autonomously navigate to specified locations. Advanced Scientific Concepts, Inc. (ASC) and the University of Minnesota...

  20. Lunar Autonomous Automatic Surface Navigation System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To address the NASA GRC Laboratory need for navigation capabilities to provide location awareness, precision position fixing, best heading, and traverse path...

  1. Airports and Navigation Aids Database System -

    Data.gov (United States)

    Department of Transportation — Airport and Navigation Aids Database System is the repository of aeronautical data related to airports, runways, lighting, NAVAID and their components, obstacles, no...

  2. Limitations of navigation through Nubaria canal, Egypt.

    Science.gov (United States)

    Samuel, Magdy G

    2014-03-01

    Alexandria port is the main Egyptian port at the Mediterranean Sea. It is connected to the Nile River through Nubaria canal, which is a main irrigation canal. The canal was designed to irrigate eight hundred thousand acres of agricultural lands, along its course which extends 100 km. The canal has three barrages and four locks to control the flow and allow light navigation by some small barges. Recently, it was decided to improve the locks located on the canal. More than 40 million US$ was invested in these projects. This decision was taken to allow larger barges and increase the transported capacity through the canal. On the other hand, navigation through canals and restricted shallow waterways is affected by several parameters related to both the channel and the vessel. Navigation lane width as well as vessel speed and maneuverability are affected by both the channel and vessel dimensions. Moreover, vessel dimensions and speed will affect the canal stability. In Egypt, there are no guide rules for navigation through narrow and shallow canals such Nubaria. This situation threatens the canal stability and safety of navigation through it. This paper discussed the characteristics of Nubaria canal and the guide rules for navigation in shallow restricted water ways. Dimensions limitation for barges navigating through Nubaria canal is presented. New safe operation rules for navigation in Nubaria canal are also presented. Moreover, the implication of navigation through locks on canal discharge is estimated.

  3. Limitations of navigation through Nubaria canal, Egypt

    Directory of Open Access Journals (Sweden)

    Magdy G. Samuel

    2014-03-01

    Full Text Available Alexandria port is the main Egyptian port at the Mediterranean Sea. It is connected to the Nile River through Nubaria canal, which is a main irrigation canal. The canal was designed to irrigate eight hundred thousand acres of agricultural lands, along its course which extends 100 km. The canal has three barrages and four locks to control the flow and allow light navigation by some small barges. Recently, it was decided to improve the locks located on the canal. More than 40 million US$ was invested in these projects. This decision was taken to allow larger barges and increase the transported capacity through the canal. On the other hand, navigation through canals and restricted shallow waterways is affected by several parameters related to both the channel and the vessel. Navigation lane width as well as vessel speed and maneuverability are affected by both the channel and vessel dimensions. Moreover, vessel dimensions and speed will affect the canal stability. In Egypt, there are no guide rules for navigation through narrow and shallow canals such Nubaria. This situation threatens the canal stability and safety of navigation through it. This paper discussed the characteristics of Nubaria canal and the guide rules for navigation in shallow restricted water ways. Dimensions limitation for barges navigating through Nubaria canal is presented. New safe operation rules for navigation in Nubaria canal are also presented. Moreover, the implication of navigation through locks on canal discharge is estimated.

  4. Ground Vehicle Navigation Using Magnetic Field Variation

    Science.gov (United States)

    Shockley, Jeremiah A.

    The Earth's magnetic field has been the bedrock of navigation for centuries. The latest research highlights the uniqueness of magnetic field measurements based on position due to large scale variations as well as localized perturbations. These observable changes in the Earth's magnetic field as a function of position provide distinct information which can be used for navigation. This dissertation describes ground vehicle navigation exploiting variation in Earth's magnetic field using a self-contained navigation system consisting of only a magnetometer and magnetic field maps. In order to achieve navigation, effective calibration enables repeatable magnetic field measurements from different vehicles and facilitates mapping of the observable magnetic field as a function of position. A new modified ellipsoid calibration technique for strapdown magnetometers in large vehicles is described, as well as analysis of position measurement generation comparing a multitude of measurement compositions using existing and newly developed likelihood techniques. Finally, navigation solutions are presented using both a position measurement and direct incorporation of the magnetometer measurements via a particle filter to demonstrate road navigation in three different environments. Emphatically, the results affirm that navigation using magnetic field variation in ground vehicles is viable and achieves adequate performance for road level navigation.

  5. Hybrid Guidance System for Relative Navigation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Future NASA architectures and missions will involve many distributed platforms that must work together. This in turn requires guidance, navigation and control...

  6. Applications of navigation for orthognathic surgery.

    Science.gov (United States)

    Bobek, Samuel L

    2014-11-01

    Stereotactic surgical navigation has been used in oral and maxillofacial surgery for orbital reconstruction, reduction of facial fractures, localization of foreign bodies, placement of implants, skull base surgery, tumor removal, temporomandibular joint surgery, and orthognathic surgery. The primary goals in adopting intraoperative navigation into these different surgeries were to define and localize operative anatomy, to localize implant position, and to orient the surgical wound. Navigation can optimize the functional and esthetic outcomes in patients with dentofacial deformities by identifying pertinent anatomic structures, transferring the surgical plan to the patient, and verifying the surgical result. This article discusses the principles of navigation-guided orthognathic surgery.

  7. Precision optical navigation guidance system

    Science.gov (United States)

    Starodubov, D.; McCormick, K.; Nolan, P.; Johnson, D.; Dellosa, M.; Volfson, L.; Fallahpour, A.; Willner, A.

    2016-05-01

    We present the new precision optical navigation guidance system approach that provides continuous, high quality range and bearing data to fixed wing aircraft during landing approach to an aircraft carrier. The system uses infrared optical communications to measure range between ship and aircraft with accuracy and precision better than 1 meter at ranges more than 7.5 km. The innovative receiver design measures bearing from aircraft to ship with accuracy and precision better than 0.5 mRad. The system provides real-time range and bearing updates to multiple aircraft at rates up to several kHz, and duplex data transmission between ship and aircraft.

  8. Interplanetary spacecraft navigation using pulsars

    CERN Document Server

    Deng, X P; You, X P; Li, M T; Keith, M J; Shannon, R M; Coles, W; Manchester, R N; Zheng, J H; Yu, X Z; Gao, D; Wu, X; Chen, D

    2013-01-01

    We demonstrate how observations of pulsars can be used to help navigate a spacecraft travelling in the solar system. We make use of archival observations of millisecond pulsars from the Parkes radio telescope in order to demonstrate the effectiveness of the method and highlight issues, such as pulsar spin irregularities, which need to be accounted for. We show that observations of four millisecond pulsars every seven days using a realistic X-ray telescope on the spacecraft throughout a journey from Earth to Mars can lead to position determinations better than approx. 20km and velocity measurements with a precision of approx. 0.1m/s.

  9. Fuzzy sets and autonomous navigation

    Science.gov (United States)

    Lea, Robert N.

    1987-01-01

    The use of fuzzy sets in modeling the human expert for certain Space Shuttle navigation problems is discussed with particular reference to onboard and ground console data monitoring tasks traditionally performed by astronauts and engineers. Specific problems include determining the quality of sensor data and of the filter state. The results obtained in this study indicate that fuzzy sets can be successfully used in modeling human reaction to rules in decision-making processes. They can also be used within software systems where guidelines have traditionally been used to set strict tolerances.

  10. Chemical compass for bird navigation

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Hore, Peter J.; Ritz, Thorsten

    2014-01-01

    Migratory birds travel spectacular distances each year, navigating and orienting by a variety of means, most of which are poorly understood. Among them is a remarkable ability to perceive the intensity and direction of the Earth's magnetic field. Biologically credible mechanisms for the detection...... increased interest following the proposal in 2000 that free radical chemistry could occur in the bird's retina initiated by photoexcitation of cryptochrome, a specialized photoreceptor protein. In the present paper we review the important physical and chemical constraints on a possible radical...

  11. 33 CFR 245.20 - Determination of hazard to navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Determination of hazard to navigation. 245.20 Section 245.20 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE REMOVAL OF WRECKS AND OTHER OBSTRUCTIONS § 245.20 Determination of hazard to...

  12. Off the Beaten tracks: Exploring Three Aspects of Web Navigation

    NARCIS (Netherlands)

    Weinreich, H.; Obendorf, H.; Herder, E.; Mayer, M.; Edmonds, H.; Hawkey, K.; Kellar, M.; Turnbull, D.

    2006-01-01

    This paper presents results of a long-term client-side Web usage study, updating previous studies that range in age from five to ten years. We focus on three aspects of Web navigation: changes in the distribution of navigation actions, speed of navigation and within-page navigation. “Navigation acti

  13. Optic flow and autonomous navigation.

    Science.gov (United States)

    Campani, M; Giachetti, A; Torre, V

    1995-01-01

    Many animals, especially insects, compute and use optic flow to control their motion direction and to avoid obstacles. Recent advances in computer vision have shown that an adequate optic flow can be computed from image sequences. Therefore studying whether artificial systems, such as robots, can use optic flow for similar purposes is of particular interest. Experiments are reviewed that suggest the possible use of optic flow for the navigation of a robot moving in indoor and outdoor environments. The optic flow is used to detect and localise obstacles in indoor scenes, such as corridors, offices, and laboratories. These routines are based on the computation of a reduced optic flow. The robot is usually able to avoid large obstacles such as a chair or a person. The avoidance performances of the proposed algorithm critically depend on the optomotor reaction of the robot. The optic flow can be used to understand the ego-motion in outdoor scenes, that is, to obtain information on the absolute velocity of the moving vehicle and to detect the presence of other moving objects. A critical step is the correction of the optic flow for shocks and vibrations present during image acquisition. The results obtained suggest that optic flow can be successfully used by biological and artificial systems to control their navigation. Moreover, both systems require fast and accurate optomotor reactions and need to compensate for the instability of the viewed world.

  14. New bionic navigation algorithm based on the visual navigation mechanism of bees

    Science.gov (United States)

    Huang, Yufeng; Liu, Yi; Liu, Jianguo

    2015-04-01

    Through some research on visual navigation mechanisms of flying insects especially honeybees, a novel navigation algorithm integrating entropy flow with Kalman filter has been introduced in this paper. Concepts of entropy image and entropy flow are also introduced, which can characterize topographic features and measure changes of the image respectively. To characterize texture feature and spatial distribution of an image, a new concept of contrast entropy image has been presented in this paper. Applying the contrast entropy image to the navigation algorithm to test its' performance of navigation and comparing with simulation results of intensity entropy image, a conclusion that contrast entropy image performs better and more robust in navigation has been made.

  15. The Navigational Power of Web Browsers

    NARCIS (Netherlands)

    Bielecki, M.; Hidders, J.; Paredaens, J.; Spielmann, M.; Tyszkiewicz, J.; Van den Bussche, J.

    2010-01-01

    We investigate the computational capabilities of Web browsers, when equipped with a standard finite automaton. We observe that Web browsers are Turingcomplete. We introduce the notion of a navigational problem, and investigate the complexity of solving Web queries and navigational problems by Web br

  16. Evolved Navigation Theory and Horizontal Visual Illusions

    Science.gov (United States)

    Jackson, Russell E.; Willey, Chela R.

    2011-01-01

    Environmental perception is prerequisite to most vertebrate behavior and its modern investigation initiated the founding of experimental psychology. Navigation costs may affect environmental perception, such as overestimating distances while encumbered (Solomon, 1949). However, little is known about how this occurs in real-world navigation or how…

  17. Disputing Viking navigation by polarized skylight.

    Science.gov (United States)

    Roslund, C; Beckman, C

    1994-07-20

    The widely held notion that the Vikings utilized polarization of skylight on overcast days for navigational purposes is demonstrated to have no scientific basis. The use of polarized skylight for navigation under partly cloudfree skies should be treated with caution and skepticism.

  18. A Semantic Navigation Model for Video Games

    Science.gov (United States)

    van Driel, Leonard; Bidarra, Rafael

    Navigational performance of artificial intelligence (AI) characters in computer games is gaining an increasingly important role in the perception of their behavior. While recent games successfully solve some complex navigation problems, there is little known or documented on the underlying approaches, often resembling a primitive conglomerate of ad-hoc algorithms for specific situations.

  19. Blavigator: a navigation aid for blind persons

    OpenAIRE

    José,João; Moreno, M.; Pinilla-Dutoit, J.; Rodrigues, J. M. F.; du Buf, J. M. H.

    2012-01-01

    Blavigator (blind navigator) is a vision aid for blind and visuaIIy impaired persons. It supports local navigation by detecting waIkable paths in the immediate vicinity of the user. It guides the user for centering on the path.

  20. Vibrotactile in-vehicle navigation system

    NARCIS (Netherlands)

    Erp, J.B.F. van; Veen, H.J. van

    2004-01-01

    A vibrotactile display, consisting ofeight vibrating elements or tactors mounted in a driver's seat, was tested in a driving simulator. Participants drove with visual, tactile and multimodal navigation displays through a built-up area. Workload and the reaction time to navigation messages were measu

  1. Traffic safety effects of navigation systems

    NARCIS (Netherlands)

    Feenstra, P.J.; Hogema, J.H.; Vonk, T.

    2007-01-01

    Abstract— To investigate effects of navigation systems on traffic safety, a literature search, a damages database analysis, a user survey and an instrumented car study were conducted. This paper presents the instrumented car study to investigate the effects of a navigation system on driving behavior

  2. On credibility improvements for automotive navigation systems

    NARCIS (Netherlands)

    Schaub, Florian; Hipp, Markus; Kargl, Frank; Weber, Michael

    2012-01-01

    Automotive navigation systems are becoming ubiquitous as driver assistance systems. Vendors continuously aim to enhance route guidance by adding new features to their systems. However, we found in an analysis of current navigation systems that many share interaction weaknesses, which can damage the

  3. Validation of principles for tactile navigation displays

    NARCIS (Netherlands)

    Erp, J.B.F. van; Werkhoven, P.J.

    2006-01-01

    Access to navigation information rapidly becomes standard in many situations, for example through GPS receivers and collision avoidance systems in cars. However, perceiving and processing the information may result in overloading the userÆs visual sense and cognitive resources. Intuitive navigation

  4. Waypoint navigation with a vibrotactile waist belt

    NARCIS (Netherlands)

    Erp, J.B.F. van; Veen, H.A.H.C. van; Jansen, C.; Dobbins, T.

    2005-01-01

    Presenting waypoint navigation on a visual display is not suited for all situations. The present experiments investigate if it is feasible to present the navigation information on a tactile display. Important design issue of the display is how direction and distance information must be coded. Import

  5. Understanding the Social Navigation User Experience

    Science.gov (United States)

    Goecks, Jeremy

    2009-01-01

    A social navigation system collects data from its users--its community--about what they are doing, their opinions, and their decisions, aggregates this data, and provides the aggregated data--community data--back to individuals so that they can use it to guide behavior and decisions. Social navigation systems empower users with the ability to…

  6. Rosetta Star Tracker and Navigation Camera

    DEFF Research Database (Denmark)

    Thuesen, Gøsta

    1998-01-01

    Proposal in response to the Invitation to Tender (ITT) issued by Matra Marconi Space (MSS) for the procurement of the ROSETTA Star Tracker and Navigation Camera.......Proposal in response to the Invitation to Tender (ITT) issued by Matra Marconi Space (MSS) for the procurement of the ROSETTA Star Tracker and Navigation Camera....

  7. Parsimonious Ways to Use Vision for Navigation

    Directory of Open Access Journals (Sweden)

    Paul Graham

    2012-05-01

    Full Text Available The use of visual information for navigation appears to be a universal strategy for sighted animals, amongst which, one particular group of expert navigators are the ants. The broad interest in studies of ant navigation is in part due to their small brains, thus biomimetic engineers expect to be impressed by elegant control solutions, and psychologists might hope for a description of the minimal cognitive requirements for complex spatial behaviours. In this spirit, we have been taking an interdisciplinary approach to the visual guided navigation of ants in their natural habitat. Behavioural experiments and natural image statistics show that visual navigation need not depend on the remembering or recognition of objects. Further modelling work suggests how simple behavioural routines might enable navigation using familiarity detection rather than explicit recall, and we present a proof of concept that visual navigation using familiarity can be achieved without specifying when or what to learn, nor separating routes into sequences of waypoints. We suggest that our current model represents the only detailed and complete model of insect route guidance to date. What's more, we believe the suggested mechanisms represent useful parsimonious hypotheses for the visually guided navigation in larger-brain animals.

  8. The Navigation Metaphor in Security Economics

    DEFF Research Database (Denmark)

    Pieters, Wolter; Barendse, Jeroen; Ford, Margaret

    2016-01-01

    The navigation metaphor for cybersecurity merges security architecture models and security economics. By identifying the most efficient routes for gaining access to assets from an attacker's viewpoint, an organization can optimize its defenses along these routes. The well-understood concept...... of navigation makes it easier to motivate and explain security investment to a wide audience, encouraging strategic security decisions....

  9. The ICRF-3: Status, Plans, and Multi-wavelength Progress on the next generation Celestial Reference Frame.

    Science.gov (United States)

    Jacobs, Christopher

    2015-08-01

    ICRF-3 seeks to improve upon the highly successful ICRF-2. Our goals are to improve the precision, spatial and frequency coverage relative to the ICRF-2 by 2018. This date is driven by the desire to create radio frames that are ready for comparison with the Gaia optical frame.Several specific actions are underway. A collaboration to improve at S/X-band precision of the Very Long Baseline Array (VLBA) Calibrator Survey's ~2200 sources, which are typically 5 times less precise than the rest of the ICRF-2, is bearing fruit and is projected to yield a factor of 3 improvement in precision. S/X-band southern hemisphere precision improvements are underway with observations using southern antennas such as the AuScope, Warkworth, and HartRAO, South Africa.We also seek to improve radio frequency coverage with X/Ka-band and K-band work. An X/Ka frame of 660 sources now has full sky coverage from the addition of a 2nd southern station in Argentina which is strengthening the southern hemisphere in general. The X/Ka-band frame's precision is now comparable to the ICRF-2 for the 530 sources in common. A K-band collaboration has formed with similar coverage and southern precision goals. By the time of this meeting, we expect K-band to complete full sky coverage with south polar cap observations and to improve spatial density north of -30 deg declination with VLBA observations.On the analysis front, special attention is being given to combination techniques both of Very Long Baseline Interferometry (VLBI) frames and of multiple data types. Consistency of the Celestial Reference Frame (CRF) with the Terrestrial Reference Frame (TRF) and Earth Oreintation Parameters (EOP) is another area of concern. Comparison of celestial frame solutions from various groups is underway in order to identify and correct systematic errors. We will discuss evidence emerging for 100 µas zonal errors in the ICRF2 in the declination range from 0 to -30 deg.Finally, work is underway to identify and

  10. Real-time precision pedestrian navigation solution using Inertial Navigation System and Global Positioning System

    Directory of Open Access Journals (Sweden)

    Yong-Jin Yoon

    2015-03-01

    Full Text Available Global Positioning System and Inertial Navigation System can be used to determine position and velocity. A Global Positioning System module is able to accurately determine position without sensor drift, but its usage is limited in heavily urbanized environments and heavy vegetation. While high-cost tactical-grade Inertial Navigation System can determine position accurately, low-cost micro-electro-mechanical system Inertial Navigation System sensors are plagued by significant errors. Global Positioning System is coupled with Inertial Navigation System to correct the errors, while Inertial Navigation System itself can be used to provide navigation solution during a Global Positioning System outage. Data from Global Positioning System and Inertial Navigation System can be integrated by extensive Kalman filtering, using loosely coupled integration architecture to provide navigation solutions. In this study, real-time low-cost loosely coupled micro-electro-mechanical system Inertial Navigation System/Global Positioning System sensors have been used for pedestrian navigation. Trial runs of Global Positioning System outages have been conducted to determine the accuracy of the system described. The micro-electro-mechanical system Inertial Navigation System/Global Positioning System can successfully project a trajectory during a Global Positioning System outage and produces a root mean square error of 9.35 m in latitude direction and 10.8 m in longitude direction. This technology is very suitable for visually impaired pedestrians.

  11. Autonomous Deep-Space Optical Navigation Project

    Science.gov (United States)

    D'Souza, Christopher

    2014-01-01

    This project will advance the Autonomous Deep-space navigation capability applied to Autonomous Rendezvous and Docking (AR&D) Guidance, Navigation and Control (GNC) system by testing it on hardware, particularly in a flight processor, with a goal of limited testing in the Integrated Power, Avionics and Software (IPAS) with the ARCM (Asteroid Retrieval Crewed Mission) DRO (Distant Retrograde Orbit) Autonomous Rendezvous and Docking (AR&D) scenario. The technology, which will be harnessed, is called 'optical flow', also known as 'visual odometry'. It is being matured in the automotive and SLAM (Simultaneous Localization and Mapping) applications but has yet to be applied to spacecraft navigation. In light of the tremendous potential of this technique, we believe that NASA needs to design a optical navigation architecture that will use this technique. It is flexible enough to be applicable to navigating around planetary bodies, such as asteroids.

  12. Navigation in spatial networks: A survey

    Science.gov (United States)

    Huang, Wei; Chen, Shengyong; Wang, Wanliang

    2014-01-01

    The study on the navigation process in spatial networks has attracted much attention in recent years due to the universal applications in real communication networks. This article surveys recent advances of the navigation problem in spatial networks. Due to the ability to overcome scaling limitations in utilizing geometric information for designing navigation algorithms in spatial networks, we summarize here several important navigation algorithms based on geometric information on both homogeneous and heterogeneous spatial networks. Due to the geometric distance employed, the cost associated with the lengths of additional long-range connections is also taken into account in this survey. Therefore, some contributions reporting how the distribution of long-range links’ lengths affects the average navigation time are summarized. We also briefly discuss two other related processes, i.e. the random walk process and the transportation process. Finally, a few open discussions are included at the end of this survey.

  13. Enhancing Navigation on Wikipedia with Social Tags

    CERN Document Server

    Zubiaga, Arkaitz

    2012-01-01

    Social tagging has become an interesting approach to improve search and navigation over the actual Web, since it aggregates the tags added by different users to the same resource in a collaborative way. This way, it results in a list of weighted tags describing its resource. Combined to a classical taxonomic classification system such as that by Wikipedia, social tags can enhance document navigation and search. On the one hand, social tags suggest alternative navigation ways, including pivot-browsing, popularity-driven navigation, and filtering. On the other hand, it provides new metadata, sometimes uncovered by documents' content, that can substantially improve document search. In this work, the inclusion of an interface to add user-defined tags describing Wikipedia articles is proposed, as a way to improve article navigation and retrieval. As a result, a prototype on applying tags over Wikipedia is proposed in order to evaluate its effectiveness.

  14. Autonomous navigation system and method

    Science.gov (United States)

    Bruemmer, David J [Idaho Falls, ID; Few, Douglas A [Idaho Falls, ID

    2009-09-08

    A robot platform includes perceptors, locomotors, and a system controller, which executes instructions for autonomously navigating a robot. The instructions repeat, on each iteration through an event timing loop, the acts of defining an event horizon based on the robot's current velocity, detecting a range to obstacles around the robot, testing for an event horizon intrusion by determining if any range to the obstacles is within the event horizon, and adjusting rotational and translational velocity of the robot accordingly. If the event horizon intrusion occurs, rotational velocity is modified by a proportion of the current rotational velocity reduced by a proportion of the range to the nearest obstacle and translational velocity is modified by a proportion of the range to the nearest obstacle. If no event horizon intrusion occurs, translational velocity is set as a ratio of a speed factor relative to a maximum speed.

  15. Autonomous navigation system and method

    Energy Technology Data Exchange (ETDEWEB)

    Bruemmer, David J [Idaho Falls, ID; Few, Douglas A [Idaho Falls, ID

    2009-09-08

    A robot platform includes perceptors, locomotors, and a system controller, which executes instructions for autonomously navigating a robot. The instructions repeat, on each iteration through an event timing loop, the acts of defining an event horizon based on the robot's current velocity, detecting a range to obstacles around the robot, testing for an event horizon intrusion by determining if any range to the obstacles is within the event horizon, and adjusting rotational and translational velocity of the robot accordingly. If the event horizon intrusion occurs, rotational velocity is modified by a proportion of the current rotational velocity reduced by a proportion of the range to the nearest obstacle and translational velocity is modified by a proportion of the range to the nearest obstacle. If no event horizon intrusion occurs, translational velocity is set as a ratio of a speed factor relative to a maximum speed.

  16. Ethical Navigation in Leadership Training

    Directory of Open Access Journals (Sweden)

    Øyvind Kvalnes

    2012-05-01

    Full Text Available Business leaders frequently face dilemmas, circumstances where whatever course of action they choose, something of important value will be offended. How can an organisation prepare its decision makers for such situations? This article presents a pedagogical approach to dilemma training for business leaders and managers. It has evolved through ten years of experience with human resource development, where ethics has been an integral part of programs designed to help individuals to become excellent in their professional roles. The core element in our approach is The Navigation Wheel, a figure used to keep track of relevant decision factors. Feedback from participants indicates that dilemma training has helped them to recognise the ethical dimension of leadership. They respond that the tools and concepts are highly relevant in relation to the challenges that occur in the working environment they return to after leadership training.http://dx.doi.org/10.5324/eip.v6i1.1778

  17. The Atacama Cosmology Telescope: Physical Properties of Sunyaev-Zel'dovich Effect Clusters on the Celestial Equator

    CERN Document Server

    Menanteau, Felipe; Barrientos, L Felipe; Battaglia, Nicholas; Bond, J Richard; Crichton, Devin; Das, Sudeep; Devlin, Mark J; Dünner, Rolando; Gralla, Megan; Hajian, Amir; Hasselfield, Matthew; Hilton, Matt; Hincks, Adam D; Hughes, John P; Infante, Leopoldo; Kosowsky, Arthur; Marriage, Tobias A; Marsden, Danica; Moodley, Kavilan; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Partridge, Bruce; Reese, Erik D; Schmitt, Benjamin L; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Switzer, Eric; Wollack, Edward J

    2012-01-01

    We present the optical and X-ray properties of 68 galaxy clusters selected via the Sunyaev-Zel'dovich Effect at 148 GHz by the Atacama Cosmology Telescope (ACT). Our sample, from an area of 504 square degrees centered on the celestial equator, is divided into two regions. The main region uses 270 square degrees of the ACT survey that overlaps with the co-added ugriz imaging from the Sloan Digital Sky Survey (SDSS) over Stripe 82 plus additional near-infrared pointed observations with the Apache Point Observatory 3.5-meter telescope. We confirm a total of 49 clusters to z~1.3, of which 22 (all at z>0.55) are new discoveries. For the second region the regular-depth SDSS imaging allows us to confirm 19 more clusters up to z~0.7, of which 10 systems are new. We present the optical richness, photometric redshifts, and separation between the SZ position and the brightest cluster galaxy (BCG). We find no significant offset between the cluster SZ centroid and BCG location and a weak correlation between optical richne...

  18. LOFAR MSSS: Detection of a low-frequency radio transient in 400 hrs of monitoring of the North Celestial Pole

    CERN Document Server

    Stewart, A J; Broderick, J W; Hassall, T E; Muñoz-Darias, T; Rowlinson, A; Swinbank, J D; Staley, T D; Molenaar, G J; Scheers, B; Grobler, T L; Pietka, M; Heald, G; McKean, J P; Bell, M E; Bonafede, A; Breton, R P; Carbone, D; Cendes, Y; Clarke, A O; Corbel, S; de Gasperin, F; Eislöffel, J; Falcke, H; Ferrari, C; Grießmeier, J -M; Hardcastle, M J; Heesen, V; Hessels, J W T; Horneffer, A; Iacobelli, M; Jonker, P; Karastergiou, A; Kokotanekov, G; Kondratiev, V I; Kuniyoshi, M; Law, C J; van Leeuwen, J; Markoff, S; Miller-Jones, J C A; Mulcahy, D; Orru, E; Pandey-Pommier, M; Pratley, L; Rol, E; Röttgering, H J A; Scaife, A M M; Shulevski, A; Sobey, C A; Stappers, B W; Tasse, C; van der Horst, A J; van Velzen, S; van Weeren, R J; Wijers, R A M J; Wijnands, R; Wise, M; Zarka, P; Alexov, A; Anderson, J; Asgekar, A; Avruch, I M; Bentum, M J; Bernardi, G; Best, P; Breitling, F; Brüggen, M; Butcher, H R; Ciardi, B; Conway, J E; Corstanje, A; de Geus, E; Deller, A; Duscha, S; Frieswijk, W; Garrett, M A; Gunst, A W; van Haarlem, M P; Hoeft, M; Hörandel, J; Juette, E; Kuper, G; Loose, M; Maat, P; McFadden, R; McKay-Bukowski, D; Moldon, J; Munk, H; Norden, M J; Paas, H; Polatidis, A G; Schwarz, D; Sluman, J; Smirnov, O; Steinmetz, M; Thoudam, S; Toribio, M C; Vermeulen, R; Vocks, C; Wijnholds, S J; Wucknitz, O; Yatawatta, S

    2015-01-01

    We present the results of a four-month campaign searching for low-frequency radio transients near the North Celestial Pole with the Low-Frequency Array (LOFAR), as part of the Multifrequency Snapshot Sky Survey (MSSS). The data were recorded between 2011 December and 2012 April and comprised 2149 11-minute snapshots, each covering 175 deg^2. We have found one convincing candidate astrophysical transient, with a duration of a few minutes and a flux density at 60 MHz of 15-25 Jy. The transient does not repeat and has no obvious optical or high-energy counterpart, as a result of which its nature is unclear. The detection of this event implies a transient rate at 60 MHz of 3.9 (+14.7, -3.7) x 10^-4 day^-1 deg^-2, and a transient surface density of 1.5 x 10^-5 deg^-2, at a 7.9-Jy limiting flux density and ~10-minute time-scale. The campaign data were also searched for transients at a range of other time-scales, from 0.5 to 297 min, which allowed us to place a range of limits on transient rates at 60 MHz as a funct...

  19. Celestial orientation with the sun not in view: lizards use a time-compensated sky polarization compass.

    Science.gov (United States)

    Maoret, Francesco; Beltrami, Giulia; Bertolucci, Cristiano; Foà, Augusto

    2014-04-01

    The present investigation was aimed at testing whether the lizard sky polarization compass is time compensated. For this purpose, ruin lizards, Podarcis sicula, were both trained and tested for orientation inside a Morris water maze under clear skies with the sun not in view. During training, lizards showed a striking bimodal orientation along the training axis, demonstrating their capability of determining the symmetry plane of the sky polarization pattern and thus the use of polarization information in orientation. After reaching criteria, lizards were kept 7 days in a 6-h fast clock-shift treatment and then released with the sun not in view. Six-hour clock-shifted lizards showed a bimodal distribution of directional choices, which was oriented perpendicularly to the training axis, as it was expected on the basis of the clock-shift. The results show that the only celestial diurnal compass mechanism that does not need a direct vision of the sun disk (i.e., the sky polarization compass) is a time-compensated compass.

  20. A high-accuracy two-position alignment inertial navigation system for lunar rovers aided by a star sensor with a calibration and positioning function

    Science.gov (United States)

    Lu, Jiazhen; Lei, Chaohua; Yang, Yanqiang; Liu, Ming

    2016-12-01

    An integrated inertial/celestial navigation system (INS/CNS) has wide applicability in lunar rovers as it provides accurate and autonomous navigational information. Initialization is particularly vital for a INS. This paper proposes a two-position initialization method based on a standard Kalman filter. The difference between the computed star vector and the measured star vector is measured. With the aid of a star sensor and the two positions, the attitudinal and positional errors can be greatly reduced, and the biases of three gyros and accelerometers can also be estimated. The semi-physical simulation results show that the positional and attitudinal errors converge within 0.07″ and 0.1 m, respectively, when the given initial positional error is 1 km and the attitudinal error is 10°. These good results show that the proposed method can accomplish alignment, positioning and calibration functions simultaneously. Thus the proposed two-position initialization method has the potential for application in lunar rover navigation.

  1. Computer navigation versus fluoroscopy-guided navigation for thoracic pedicle screw placement: a meta-analysis.

    Science.gov (United States)

    Meng, Xiao-Tong; Guan, Xiao-Fei; Zhang, Hai-Long; He, Shi-Sheng

    2016-07-01

    Although application of intraoperative computer navigation technique had been integrated into placement of pedicle screws (PSs) in thoracic fusion for years, its security and practicability remain controversial. The aim of this study is to evaluate the accuracy, the operative time consumption, the amount of intraoperative blood loss, time of pedicle insertion and the incidence of complications of thoracic pedicle screw placement in patients with thoracic diseases such as scoliosis and kyphosis. Pubmed, Web of Knowledge, and Google scholar were searched to identify comparative studies of thoracic pedicle screw placement between intraoperative computer navigation and fluoroscopy-guided navigation. Outcomes of malposition rate, operative time consumption, insertion time, intraoperative blood loss, and the incidence of complications are evaluated. Fourteen articles including 1723 patients and 9019 PSs were identified matching inclusion criteria. The malposition rate was lower (RR: 0.33, 95 % CI: 0.28-0.38, P navigation group than that in fluoroscopy-guided navigation group; the operative time was significantly longer [weighted mean difference (WMD) = 23.66, 95 % CI: 14.74-32.57, P navigation group than that in fluoroscopy-guided navigation group. The time of insertion was shorter (WMD = -1.88, 95 % CI: -2.25- -1.52, P navigation group than that in fluoroscopy-guided navigation group. The incidence of complications was lower (RR = 0. 23, 95 % CI: 0.12-0.46, P navigation group than that in the other group. The intraoperative blood loss was fewer (WMD = -167.49, 95 % CI: -266.39- -68.58, P navigation group than that in the other. In conclusion, the meta-analysis of thoracic pedicle screw placement studies clearly demonstrated lower malposition rate, less intraoperative blood loss, and fewer complications when using computer navigation. This result provides strong evidence that computer technology could be safer and more reliable than

  2. Testing the Preliminary X-33 Navigation System

    Science.gov (United States)

    Lomas, James J.; Mitchell, Daniel W.; Freestone, Todd M.; Lee, Charles; Lessman, Craig; Foster, Lee D. (Technical Monitor)

    2001-01-01

    The X-33 Reusable Launch Vehicle (RLV) must meet the demanding requirements of landing autonomously on a narrow landing strip following a flight that reaches an altitude of up to 200,000 feet and a speed in excess of Mach 9 with significant in-flight energy bleed-off maneuvers. To execute this flight regimen a highly reliable avionics system has been designed that includes three LN-100G Inertial Navigation System/Global Positioning System (INS/GPS) units as the primary navigation system for the X-33. NASA's Marshall Space Flight Center (MSFC) tested an INS/GPS system in real-time simulations to determine the ability of this navigation suite to meet the in flight and autonomous landing requirements of the X-33 RLV. A total of sixty-one open loop tests were performed to characterize the navigation accuracy of the LN-100G. Twenty-seven closed-loop tests were also performed to evaluate the performance of the X-33 Guidance, Navigation and Control (GN&C) algorithms with the real navigation hardware. These closed-loop tests were also designed to expose any integration or operational issues with the real-time X-33 vehicle simulation. Dynamic road tests of the INS/GPS were conducted by Litton to assess the performance of differential and nondifferential INS/GPS hybrid navigation solutions. The results of the simulations and road testing demonstrate that this novel solution is capable of meeting the demanding requirements of take-off, in-flight navigation, and autonomous landing of the X-33 RLV. This paper describes the test environment developed to stimulate the LN-100G and discusses the results of this test effort. This paper also presents recommendations for a navigation system suitable to an operational RLV system.

  3. Inner Harbor Navigation Canal Basin Velocity Analysis

    Science.gov (United States)

    2014-10-01

    ER D C/ CH L TR -1 4- 12 Inner Harbor Navigation Canal Basin Velocity Analysis Co as ta l a nd H yd ra ul ic s La bo ra to ry...library at http://acwc.sdp.sirsi.net/client/default. ERDC/CHL TR-14-12 October 2014 Inner Harbor Navigation Canal Basin Velocity Analysis...system of levees, gates, and drainage structures in the Inner Harbor Navigation Canal (IHNC) basin and the greater New Orleans, Louisiana, area. Two

  4. Geomagnetic Navigation in Sea Turtles

    Science.gov (United States)

    Lohmann, K.; Putman, N.; Lohmann, C.

    2011-12-01

    Young loggerhead sea turtles (Caretta caretta) from eastern Florida undertake a transoceanic migration in which they gradually circle the north Atlantic Ocean before returning to the North American coast. Newly hatched turtles (hatchlings) begin the migration with a 'magnetic map' in which regional magnetic fields function as navigational markers and elicit changes in swimming direction at crucial geographic boundaries. In laboratory experiments, young turtles that had never before been in the ocean were exposed to fields like those that exist at various, widely separated locations along their transoceanic migratory route. Turtles responded by swimming in directions that would, in each case, help them remain within the North Atlantic gyre currents and advance along the migratory pathway. The results demonstrate that turtles can derive both longitudinal and latitudinal information from the Earth's field, and provide strong evidence that hatchling loggerheads inherit a remarkably elaborate set of responses that function in guiding them along their open-sea migratory route. For young sea turtles, couplings of oriented swimming to regional magnetic fields appear to provide the fundamental building blocks from which natural selection can sculpt a sequence of responses capable of guiding first-time ocean migrants along complex migratory routes. The results imply that hatchlings from different populations in different parts of the world are likely to have magnetic navigational responses uniquely suited for the migratory routes that each group follows. Thus, from a conservation perspective, turtles from different populations are not interchangeable. From an evolutionary perspective, the responses are not incompatible with either secular variation or magnetic polarity reversals. As Earth's field gradually changes, strong selective pressure presumably acts to maintain an approximate match between the responses of hatchlings and the fields that exist at critical points along

  5. INS/CNS integrated navigation method for lunar rover%月球车的惯性/天文组合导航新方法

    Institute of Scientific and Technical Information of China (English)

    宁晓琳; 蔡洪炜; 吴伟仁; 房建成; 张学亮

    2011-01-01

    In the second phase of China's lunar exploration program, a lunar rover will be used to survey the lunar surface. Effective navigation and control of lunar rover guarantees the success of the mission. Autonomous navigation is a critical technology which compensates for the limitations of ground tracking and control. Inertial navigation system (INS) and celestial navigation system (CNS) are two kinds of important autonomous navigation systems. However, the error of INS accumulates with time and precision of CNS is low in a short period of time. In order to solve these problems, a new INS/CNS integrated navigation method for lunar rovers is presented. This method acquires a high navigation precision by periodically fusing estimates of INS and CNS. Simulation results show that a position estimation error within 25 m is obtained, which demonstrates that the method is a promising choice for long period, long distance and high precision navigation of lunar rover.%我国月球探测二期工程将进行月面巡视探测任务,而月球车的导航和控制是任务完成的重要保障.月球车实现自主导航可以弥补地面测控的局限性,是目前亟待解决的关键技术.惯性导航和天文导航都是适用于月球车的自主导航方法,但惯性导航误差随时间积累,天文导航短时精度较低.为此,提出一种月球车自主惯性/天文组合导航新方法,通过天文导航不断对惯性导航进行校正,提高了导航的精度和可靠性.仿真结果表明,该惯性/天文组合导航方法的位置精度在25 m以内,可满足月球车长时间、长距离的高精度导航要求.

  6. 14 CFR 63.61 - Flight navigator courses.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Flight navigator courses. 63.61 Section 63...) AIRMEN CERTIFICATION: FLIGHT CREWMEMBERS OTHER THAN PILOTS Flight Navigators § 63.61 Flight navigator courses. An applicant for approval of a flight navigator course must submit a letter to the...

  7. 33 CFR 207.800 - Collection of navigation statistics.

    Science.gov (United States)

    2010-07-01

    ... statistics. 207.800 Section 207.800 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS § 207.800 Collection of navigation statistics. (a... received by the Waterborne Commerce Statistics Center within 30 days after the close of the month in...

  8. Plenoptic Imager for Automated Surface Navigation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Autonomous and semi-autonomous robotic systems require information about their surroundings in order to navigate properly. A video camera machine vision system can...

  9. Navigation with a passive brain based interface

    NARCIS (Netherlands)

    Erp, J.B.F. van; Werkhoven, P.J.; Thurlings, M.E.; Brouwer, A.-M.

    2009-01-01

    In this paper, we describe a Brain Computer Interface (BCI) for navigation. The system is based on detecting brain signals that are elicited by tactile stimulation on the torso indicating the desired direction.

  10. 5th China Satellite Navigation Conference

    CERN Document Server

    Jiao, Wenhai; Wu, Haitao; Lu, Mingquan

    2014-01-01

    China Satellite Navigation Conference (CSNC) 2014 Proceedings presents selected research papers from CSNC2014, held on 21-23 May in Nanjing, China. The theme of CSNC2014 is 'BDS Application: Innovation, Integration and Sharing'. These papers discuss the technologies and applications of the Global Navigation Satellite System (GNSS), and the latest progress made in the China BeiDou System (BDS) especially. They are divided into 9 topics to match the corresponding sessions in CSNC2014, which broadly covered key topics in GNSS. Readers can learn about the BDS and keep abreast of the latest advances in GNSS techniques and applications.  SUN Jiadong is the Chief Designer of the Compass/ BDS, and the Academician of Chinese Academy of Sciences (CAS); JIAO Wenhai is a researcher at China Satellite Navigation Office; WU Haitao is a professor at Navigation Headquarters, CAS; LU Mingquan is a professor at Department of Electronic Engineering of Tsinghua University.

  11. Autonomous Robot Navigation based on Visual Landmarks

    DEFF Research Database (Denmark)

    Livatino, Salvatore

    2005-01-01

    autonomous navigation and self-localization using automatically selected landmarks. The thesis investigates autonomous robot navigation and proposes a new method which benefits from the potential of the visual sensor to provide accuracy and reliability to the navigation process while relying on naturally...... update of the estimated robot position while the robot is moving. In order to make the system autonomous, both acquisition and observation of landmarks have to be carried out automatically. The thesis consequently proposes a method for learning and navigation of a working environment and it explores...... of the proposed method is based on a system with a simple setup. The novelty and potentiality, are in combining algorithms for panoramic view-synthesis, attention selection, stereo reconstruction, triangulation, optimal triplet selection, and image-based rendering. Experiments demonstrate that the system can...

  12. NOAA Seamless Raster Navigational Charts (RNC)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Seamless Raster Chart Server provides a seamless collarless mosaic of the NOAA Raster Navigational Charts (RNC). The RNC are a collection of approximately...

  13. Venous catheterization with ultrasound navigation

    Science.gov (United States)

    Kasatkin, A. A.; Urakov, A. L.; Nigmatullina, A. R.

    2015-11-01

    By ultrasound scanning it was determined that respiratory movements made by chest of healthy and sick person are accompanied by respiratory chest rise of internal jugular veins. During the exhalation of an individual diameter of his veins increases and during the breath it decreases down to the complete disappearing if their lumen. Change of the diameter of internal jugular veins in different phases can influence significantly the results of vein puncture and cauterization in patients. The purpose of this research is development of the method increasing the efficiency and safety of cannulation of internal jugular veins by the ultrasound visualization. We suggested the method of catheterization of internal jugular veins by the ultrasound navigation during the execution of which the puncture of venous wall by puncture needle and the following conduction of J-guide is carried out at the moment of patient's exhalation. This method decreases the risk of complications development during catheterization of internal jugular vein due to exclusion of perforating wound of vein and subjacent tissues and anatomical structures.

  14. Venous catheterization with ultrasound navigation

    Energy Technology Data Exchange (ETDEWEB)

    Kasatkin, A. A., E-mail: ant-kasatkin@yandex.ru; Nigmatullina, A. R. [Izhevsk State Medical Academy, Kommunarov street, 281, Izhevsk, Russia, 426034 (Russian Federation); Urakov, A. L., E-mail: ant-kasatkin@yandex.ru [Institute of Mechanics Ural Branch of Russian Academy of Sciences, T.Baramzinoy street 34, Izhevsk, Russia, 426067, Izhevsk (Russian Federation); Izhevsk State Medical Academy, Kommunarov street, 281, Izhevsk, Russia, 426034 (Russian Federation)

    2015-11-17

    By ultrasound scanning it was determined that respiratory movements made by chest of healthy and sick person are accompanied by respiratory chest rise of internal jugular veins. During the exhalation of an individual diameter of his veins increases and during the breath it decreases down to the complete disappearing if their lumen. Change of the diameter of internal jugular veins in different phases can influence significantly the results of vein puncture and cauterization in patients. The purpose of this research is development of the method increasing the efficiency and safety of cannulation of internal jugular veins by the ultrasound visualization. We suggested the method of catheterization of internal jugular veins by the ultrasound navigation during the execution of which the puncture of venous wall by puncture needle and the following conduction of J-guide is carried out at the moment of patient’s exhalation. This method decreases the risk of complications development during catheterization of internal jugular vein due to exclusion of perforating wound of vein and subjacent tissues and anatomical structures.

  15. Inertial sensors for smartphones navigation.

    Science.gov (United States)

    Dabove, P; Ghinamo, G; Lingua, A M

    2015-01-01

    The advent of smartphones and tablets, means that we can constantly get information on our current geographical location. These devices include not only GPS/GNSS chipsets but also mass-market inertial platforms that can be used to plan activities, share locations on social networks, and also to perform positioning in indoor and outdoor scenarios. This paper shows the performance of smartphones and their inertial sensors in terms of gaining information about the user's current geographical locatio n considering an indoor navigation scenario. Tests were carried out to determine the accuracy and precision obtainable with internal and external sensors. In terms of the attitude and drift estimation with an updating interval equal to 1 s, 2D accuracies of about 15 cm were obtained with the images. Residual benefits were also obtained, however, for large intervals, e.g. 2 and 5 s, where the accuracies decreased to 50 cm and 2.2 m, respectively.

  16. Shape Perception and Navigation in Blind Adults

    Science.gov (United States)

    Gori, Monica; Cappagli, Giulia; Baud-Bovy, Gabriel; Finocchietti, Sara

    2017-01-01

    Different sensory systems interact to generate a representation of space and to navigate. Vision plays a critical role in the representation of space development. During navigation, vision is integrated with auditory and mobility cues. In blind individuals, visual experience is not available and navigation therefore lacks this important sensory signal. In blind individuals, compensatory mechanisms can be adopted to improve spatial and navigation skills. On the other hand, the limitations of these compensatory mechanisms are not completely clear. Both enhanced and impaired reliance on auditory cues in blind individuals have been reported. Here, we develop a new paradigm to test both auditory perception and navigation skills in blind and sighted individuals and to investigate the effect that visual experience has on the ability to reproduce simple and complex paths. During the navigation task, early blind, late blind and sighted individuals were required first to listen to an audio shape and then to recognize and reproduce it by walking. After each audio shape was presented, a static sound was played and the participants were asked to reach it. Movements were recorded with a motion tracking system. Our results show three main impairments specific to early blind individuals. The first is the tendency to compress the shapes reproduced during navigation. The second is the difficulty to recognize complex audio stimuli, and finally, the third is the difficulty in reproducing the desired shape: early blind participants occasionally reported perceiving a square but they actually reproduced a circle during the navigation task. We discuss these results in terms of compromised spatial reference frames due to lack of visual input during the early period of development. PMID:28144226

  17. Precise laser gyroscope for autonomous inertial navigation

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, A G; Molchanov, A V; Izmailov, E A [Joint Stock Company ' Moscow Institute of Electromechanics and Automatics' , Moscow (Russian Federation); Chirkin, M V [Ryazan State Radio Engineering University (Russian Federation)

    2015-01-31

    Requirements to gyroscopes of strapdown inertial navigation systems for aircraft application are formulated. The construction of a ring helium – neon laser designed for autonomous navigation is described. The processes that determine the laser service life and the relation between the random error of the angular velocity measurement and the surface relief features of the cavity mirrors are analysed. The results of modelling one of the promising approaches to processing the laser gyroscope signals are presented. (laser gyroscopes)

  18. Navigation System for Reusable Launch Vehicle

    OpenAIRE

    Schlotterer, Markus

    2008-01-01

    PHOENIX is a downscaled experimental vehicle to demonstrate automatic landing capabilities of future Reusable Launch Vehicles (RLVs). PHOENIX has flown in May 2004 at NEAT (North European Aerospace Test range) in Vidsel, Sweden. As the shape of the vehicle has been designed for re-entry, the dynamics are very high and almost unstable. This requires a fast and precise GNC system. This paper describes the navigation system and the navigation filter of PHOENIX. The system is introduced and the h...

  19. Navigation and Control of an Autonomous Vehicle

    OpenAIRE

    Schworer, Ian Josef

    2005-01-01

    The navigation and control of an autonomous vehicle is a highly complex task. Making a vehicle intelligent and able to operate â unmannedâ requires extensive theoretical as well as practical knowledge. An autonomous vehicle must be able to make decisions and respond to situations completely on its own. Navigation and control serves as the major limitation of the overall performance, accuracy and robustness of an autonomous vehicle. This thesis will address this problem and propose a uni...

  20. Visual navigation for an autonomous mobile vehicle

    OpenAIRE

    Peterson, Kevin Robert

    1992-01-01

    Approved for public release; distribution is unlimited Image understanding for a mobile robotic vehicle is an important and complex task for ensuring safe navigation and extended autonomous operations. The goal of this work is to implement a working vision-based navigation control mechanism within a known environment onboard the autonomous mobile vehicle Yamabico-II. Although installing a working hardware system was not accomplished, the image processing, model description, pattern match...

  1. Navigation domain representation for interactive multiview imaging.

    Science.gov (United States)

    Maugey, Thomas; Daribo, Ismael; Cheung, Gene; Frossard, Pascal

    2013-09-01

    Enabling users to interactively navigate through different viewpoints of a static scene is a new interesting functionality in 3D streaming systems. While it opens exciting perspectives toward rich multimedia applications, it requires the design of novel representations and coding techniques to solve the new challenges imposed by the interactive navigation. In particular, the encoder must prepare a priori a compressed media stream that is flexible enough to enable the free selection of multiview navigation paths by different streaming media clients. Interactivity clearly brings new design constraints: the encoder is unaware of the exact decoding process, while the decoder has to reconstruct information from incomplete subsets of data since the server generally cannot transmit images for all possible viewpoints due to resource constrains. In this paper, we propose a novel multiview data representation that permits us to satisfy bandwidth and storage constraints in an interactive multiview streaming system. In particular, we partition the multiview navigation domain into segments, each of which is described by a reference image (color and depth data) and some auxiliary information. The auxiliary information enables the client to recreate any viewpoint in the navigation segment via view synthesis. The decoder is then able to navigate freely in the segment without further data request to the server; it requests additional data only when it moves to a different segment. We discuss the benefits of this novel representation in interactive navigation systems and further propose a method to optimize the partitioning of the navigation domain into independent segments, under bandwidth and storage constraints. Experimental results confirm the potential of the proposed representation; namely, our system leads to similar compression performance as classical inter-view coding, while it provides the high level of flexibility that is required for interactive streaming. Because of

  2. An integrated platform for inertial navigation systems

    Science.gov (United States)

    Dumitrascu, Ana; Tamas, Razvan D.; Caruntu, George; Bobirca, Daniel

    2015-02-01

    In this paper we propose a new configuration for an inertial navigation system (INS), type strap down, designed to be used onboard a ship. The system consists of an inertial navigation unit (IMU), using a 9-axis inertial sensor and pressure and temperature sensors, a GPS module, various interfaces for optimal communication and command, a microcontroller for data processing and computing and a power supply.

  3. Neurobiologically inspired mobile robot navigation and planning

    Directory of Open Access Journals (Sweden)

    Mathias Quoy

    2007-11-01

    Full Text Available After a short review of biologically inspired navigation architectures, mainly relying on modeling the hippocampal anatomy, or at least some of its functions, we present a navigation and planning model for mobile robots. This architecture is based on a model of the hippocampal and prefrontal interactions. In particular, the system relies on the definition of a new cell type “transition cells” that encompasses traditional “place cells”.

  4. Speech Recognition Technology Applied to Intelligent Mobile Navigation System

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The capability of human-computer interaction reflects the intelligent degree of mobile navigation system.The navigation data and functions of mobile navigation system are divided into system commands and non-system commands in this paper.And then a group of speech commands are Abstracted.This paper applies speech recognition technology to intelligent mobile navigation system to process speech commands and does some deep research on the integration of speech recognition technology with mobile navigation system.The navigation operation can be performed by speech commands,which makes human-computer interaction easy during navigation.Speech command interface of navigation system is implemented by Dutty ++ Software,which is based on speech recognition system -Via Voice of IBM.Through navigation experiments,navigation can be done almost without keyboard,which proved that human-computer interaction is very convenient by speech commands and the reliability is also higher.

  5. Unmanned vehicle mobility: Limits of autonomous navigation

    Science.gov (United States)

    McCormac, A. W.; Hanna, D. M.; McFee, J.

    Considerable research is being conducted on the development of unmanned vehicles for military and civilian applications, particularly for hostile environments. It is desirable to produce a vehicle which can select its own route, not requiring remote navigation, but then it would be required to sense its surroundings. Although imaging systems and modern computers make this possible, the extreme data processing demands usually make it impractical. It is suggested that an inverse relationship exists between vehicle mobility and the complexity of the autonomous navigation system required for an unmanned vehicle. An overview of vehicle navigation is presented which shows the degree to which navigation is affected by increasing inherent mobility. If the inherent mobility of a vehicle is greatly enhanced, the scene image processing requirements and navigational computations are greatly simplified. This means the vehicle path selection and speed and steering adjustments may be made more quickly, resulting in higher vehicle speeds whenever possible. Combined with reduced deviation from the intended path, this would greatly increase the speed of the vehicle from one given point to another, suggesting that high speed autonomous navigation may be feasible.

  6. Fusion of Onboard Sensors for Better Navigation

    Directory of Open Access Journals (Sweden)

    Ravi Shankar

    2013-03-01

    Full Text Available This paper presents simulation results of navigation sensors such as integrated navigation system (INS, global navigation satellite system (GNSS and TACAN sensors onboard an aircraft to find the navigation solutions. Mathematical models for INS, GNSS (GPS satellite trajectories, GPS receiver and TACAN characteristics are simulated in Matlab. The INS simulation generates the output for position, velocity and attitude based on aerosond dynamic model. The GPS constellation is generated based on the YUMA almanac data. The GPS dilution of precession (DOP parameters are calculated and the best combination of four satellites (minimum PDOP is used for calculating the user position and velocity. The INS, GNSS, and TACAN solutions are integrated through loosely coupled extended Kalman filter for calculating the optimum navigation solution. The work is starting stone for providing aircraft based augmentation system for required navigation performance in terms of availability, accuracy, continuity and integrity.Defence Science Journal, 2013, 63(2, pp.145-152, DOI:http://dx.doi.org/10.14429/dsj.63.4256

  7. NFC internal: an indoor navigation system.

    Science.gov (United States)

    Ozdenizci, Busra; Coskun, Vedat; Ok, Kerem

    2015-03-27

    Indoor navigation systems have recently become a popular research field due to the lack of GPS signals indoors. Several indoors navigation systems have already been proposed in order to eliminate deficiencies; however each of them has several technical and usability limitations. In this study, we propose NFC Internal, a Near Field Communication (NFC)-based indoor navigation system, which enables users to navigate through a building or a complex by enabling a simple location update, simply by touching NFC tags those are spread around and orient users to the destination. In this paper, we initially present the system requirements, give the design details and study the viability of NFC Internal with a prototype application and a case study. Moreover, we evaluate the performance of the system and compare it with existing indoor navigation systems. It is seen that NFC Internal has considerable advantages and significant contributions to existing indoor navigation systems in terms of security and privacy, cost, performance, robustness, complexity, user preference and commercial availability.

  8. NFC Internal: An Indoor Navigation System

    Directory of Open Access Journals (Sweden)

    Busra Ozdenizci

    2015-03-01

    Full Text Available Indoor navigation systems have recently become a popular research field due to the lack of GPS signals indoors. Several indoors navigation systems have already been proposed in order to eliminate deficiencies; however each of them has several technical and usability limitations. In this study, we propose NFC Internal, a Near Field Communication (NFC-based indoor navigation system, which enables users to navigate through a building or a complex by enabling a simple location update, simply by touching NFC tags those are spread around and orient users to the destination. In this paper, we initially present the system requirements, give the design details and study the viability of NFC Internal with a prototype application and a case study. Moreover, we evaluate the performance of the system and compare it with existing indoor navigation systems. It is seen that NFC Internal has considerable advantages and significant contributions to existing indoor navigation systems in terms of security and privacy, cost, performance, robustness, complexity, user preference and commercial availability.

  9. Advanced Navigation System for Aircraft Applications

    Directory of Open Access Journals (Sweden)

    G. Satheesh Reddy

    2013-03-01

    Full Text Available Various forms of navigation are present in today’s world, leading from satellite based navigation to several archaic forms of navigation like star gazing. Now, lots of technologies are available to achieve this but with certain limitations. For example, FOG based navigation provides accuracy with in 0.10-100 range which is not sufficient for various military applications. Therefore, there is a need to design a system which will have better accuracy and thus requires development of ring laser gyro-based inertial systems. This paper concentrates on the aided navigation system based on ring laser gyro of 0.01 deg/hr class and GPS - GLONASS to further enhance the capability of system in terms of accuracy. The usage of such systems not only provides accurate results momentarily but it also persists for longer duration with the aid of GPS - GLONASS for applications like aircraft, ship and long range missiles. The system provides accuracy of the level of 1 Nm/hr in pure navigation and 30 m with the aid of GPS - GLONASS. Apart from this, the availability of gyro-compass and baro-inertial algorithms further enhances the system capabilities and made them self dependent to the major extent.Defence Science Journal, 2013, 63(2, pp.131-137, DOI:http://dx.doi.org/10.14429/dsj.63.4254

  10. Forty years of olfactory navigation in birds.

    Science.gov (United States)

    Gagliardo, Anna

    2013-06-15

    Forty years ago, Papi and colleagues discovered that anosmic pigeons cannot find their way home when released at unfamiliar locations. They explained this phenomenon by developing the olfactory navigation hypothesis: pigeons at the home loft learn the odours carried by the winds in association with wind direction; once at the release site, they determine the direction of displacement on the basis of the odours perceived locally and orient homeward. In addition to the old classical experiments, new GPS tracking data and observations on the activation of the olfactory system in displaced pigeons have provided further evidence for the specific role of olfactory cues in pigeon navigation. Although it is not known which odours the birds might rely on for navigation, it has been shown that volatile organic compounds in the atmosphere are distributed as fairly stable gradients to allow environmental odour-based navigation. The investigation of the potential role of olfactory cues for navigation in wild birds is still at an early stage; however, the evidence collected so far suggests that olfactory navigation might be a widespread mechanism in avian species.

  11. Global navigation system with RFID tags

    Science.gov (United States)

    Tsukiyama, Toshifumi

    2002-02-01

    A new navigation system is described for a mobile robot moving around in man-made environments such as hallways in a building. The system is based on a commercial three-wheel mobile platform with the addition of a Linux-based laptop computer, a Radio Frequency Identification (RDID) tag sensor and a vision system. At critical junctions such as the intersection of two passages the navigation system must identify the robot's location on a given map. We propose a method using RFID tags as landmarks. Each RFID tag has a unique ID number corresponding to its location on the map. The navigation system can decide the next movement (left-turn, right-turn and so on) toward a given goal based on this number. The navigation system also can automatically follow walls using the vision system. Since the equipment setup is very simple and the navigation system is easily combined with general mobile robot systems, our proposed technique would be useful for real-world robotic applications such as intelligent navigation for motorized wheelchairs.

  12. Fuzzy Behavior Modulation with Threshold Activation for Autonomous Vehicle Navigation

    Science.gov (United States)

    Tunstel, Edward

    2000-01-01

    This paper describes fuzzy logic techniques used in a hierarchical behavior-based architecture for robot navigation. An architectural feature for threshold activation of fuzzy-behaviors is emphasized, which is potentially useful for tuning navigation performance in real world applications. The target application is autonomous local navigation of a small planetary rover. Threshold activation of low-level navigation behaviors is the primary focus. A preliminary assessment of its impact on local navigation performance is provided based on computer simulations.

  13. Target relative navigation results from hardware-in-the-loop tests using the sinplex navigation system

    NARCIS (Netherlands)

    Steffes, S.; Dumke, M.; Heise, D.; Sagliano, M.; Samaan, M.; Theil, S.; Boslooper, E.C.; Oosterling, J.A.J.; Schulte, J.; Skaborn, D.; Söderholm, S.; Conticello, S.; Esposito, M.; Yanson, Y.; Monna, B.; Stelwagen, F.; Visee, R.

    2014-01-01

    The goal of the SINPLEX project is to develop an innovative solution to significantly reduce the mass of the navigation subsystem for exploration missions which include landing and/or rendezvous and capture phases. The system mass is reduced while still maintaining good navigation performance as com

  14. 75 FR 50884 - Navigation and Navigable Waters; Technical, Organizational, and Conforming Amendments, Sector...

    Science.gov (United States)

    2010-08-18

    ... INFORMATION: In FR doc 2010-19754 appearing on page 48564 in the issue of Wednesday, August 11, 2010, the..., Organizational, and Conforming Amendments, Sector Columbia River; Correction AGENCY: Coast Guard, DHS. ACTION... read ``Navigation and Navigable Waters; Technical, Organizational, and Conforming Amendments,...

  15. 77 FR 42637 - Navigation and Navigable Waters; Technical, Organizational, and Conforming Amendments; Corrections

    Science.gov (United States)

    2012-07-20

    ... Register of Thursday, June 21, 2012 (77 FR 37305). The regulations related to technical, organizational and... 21, 2012 (77 FR 37305), the Coast Guard published a final rule entitled ``Navigation and Navigable..., Organizational, and Conforming Amendments; Corrections AGENCY: Coast Guard, DHS. ACTION: Correcting...

  16. Does Navigation Always Predict Performance? Effects of Navigation on Digital Reading Are Moderated by Comprehension Skills

    Science.gov (United States)

    Naumann, Johannes; Salmerón, Ladislao

    2016-01-01

    This study investigated interactive effects of navigation and offline comprehension skill on digital reading performance. As indicators of navigation, relevant page selection and irrelevant page selection were considered. In 533 Spanish high school students aged 11-17 positive effects of offline comprehension skill and relevant page selection on…

  17. Research on the airborne SINS/CNS integrated navigation system assisted by BD navigation system

    Science.gov (United States)

    Xie, Mei-lin; Yang, Xiao-xu; Han, Jun-feng; Wei, Yu; Yue, Peng; Deng, Xiao-guo; Huang, Wei

    2016-01-01

    When the star navigation system working during the day, the strong sky background radiation lead to a result that the detect target light is too weak, in the field of view, because of the limitation on the number of the navigation star, usually choose the single star navigation work mode. In order to improve the reliability of the airborne SINS/CNS integrated navigation system, meet the demand of the long-endurance and high precision navigation, use the tight combination way, single star patrol algorithm to get the position and attitude. There exists filtering divergence problem because of the model error and the system measurement noise is uncertain, put forward a new fuzzy adaptive kalman filtering algorithm. Adjust the size of measurement noise to prevent the filter divergence; the positioning accuracy of integrated navigation system can be improved through BeiDou satellite. Without the information of BeiDou satellite, based on the level of the virtual reference, the navigation precision of integrated navigation system can be ensured over a period of time.

  18. 76 FR 31831 - Navigation and Navigable Waters; Technical, Organizational, and Conforming Amendments

    Science.gov (United States)

    2011-06-02

    ..., 164, 166, 167, and 169 RIN 1625-AB69 Navigation and Navigable Waters; Technical, Organizational, and... Property G. Civil Justice Reform H. Protection of Children I. Indian Tribal Governments J. Energy Effects K.... 553(b)(B) as this rule consists only of corrections and editorial, organizational, and...

  19. 33 CFR 66.05-25 - Change and modification of State aids to navigation.

    Science.gov (United States)

    2010-07-01

    ... aids to navigation. 66.05-25 Section 66.05-25 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION State Aids to Navigation § 66.05-25 Change and modification of State aids to navigation. Wherever a State Administrator determines...

  20. 33 CFR 66.05-35 - Private aids to navigation other than State owned.

    Science.gov (United States)

    2010-07-01

    ... HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION State Aids to Navigation § 66.05-35 Private... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Private aids to navigation other... States, shall establish, erect or maintain in State waters for private aids to navigation any aid...

  1. 33 CFR 66.01-50 - Protection of private aids to navigation.

    Science.gov (United States)

    2010-07-01

    ... SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-50 Protection of private aids to navigation. Private aids to navigation lawfully maintained under... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Protection of private aids...

  2. New celestial reference system

    Science.gov (United States)

    Seidelmann, P. K.; Kaplan, G. H.; van Flandern, T. C.

    It is pointed out that the IAU (1976) System of Astronomical Constants, the FK5 and new lunar and planetary theories are being introduced in 1984. The investigation and planning for the transition have revealed the complex interdependencies between observational techniques and the reference systems and their strong link to the rotating and orbiting earth. Details for the conversion to the new system are given. The concepts for a future reference system are developed, based on separating the real motions involved in such a way that observations from various moving platforms can be related to the appropriate coordinate system without involving motions that are not intrinsically involved in the observations. As a consequence, the reference systems determined or used in space, while affected by aberration and parallax, would logically be defined with no dependence on precession, nutation, polar motion, or Universal Time, all of which are concerned with motions of the earth's surface.

  3. Terrestrial and Celestial Cartography,

    Science.gov (United States)

    1979-05-01

    Arizona, Tucson, 1972) 69. Thirteen-Color Photometry of 1380 Bright Stars. H. L. Johnson, and R. I. Mitchell, Revista Mexicana de Astronomia y Astrofisica...1. 299 (1975) 90. A New Michelson Spec trophotometer System. H. L. Johnson, Revista Mexicana de Astronomia y Astrofisica, 2, 219 (1977) 91. An Atlas...of Stellar Spectra. I. H. L. Johnson. Revista Mexicana de Astronomia y Astrofisica, 2, 71 (1977) 92. An Atlas of Stellar Spectra. II. H. L. Johnson

  4. On Celestial Wings,

    Science.gov (United States)

    1995-11-01

    and headed out into the sunshine of a bright new Monday morning. I was on the way to breakfast at the mess hall a block away. It seemed that it would...He stood on a box and addressed his weary audience through an interpreter. His message was short and to the point: "You are our eternal enemy! You may...afternoon was an eternity . The sun seemed to hang in the sky as if it would never go down. Then, when darkness came, it seemed as if everything had

  5. Global navigation satellite system; Jisedai kokoho senjo system

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, S.; Suga, S. [Toshiba Corp., Tokyo (Japan)

    2000-05-01

    The safety of civil aviation relies on ground navigation aids. In areas where there are no ground aids and on oceanic air routes, aircraft must depend on their own navigation system. The predicted increase in civil aviation traffic in the near future will make it difficult for current navigation aids to support navigation in all phases of flights. To avoid this problem, the International Civil Aviation Organization (ICAO) is directing the establishment of standards for the global navigation satellite system (GNSS). GNSS employs navigation satellites, such as those of the global positioning system (GPS), to provide navigation capability throughout the world. In Japan, the Electronic Navigation Research Institute, the Ministry of Transport, and the Japan civil Aviation Promotion Foundation are carrying out research on this navigation system. Toshiba has been providing experimental equipment for this research. (author)

  6. Intelligent navigation to improve obstetrical sonography.

    Science.gov (United States)

    Yeo, Lami; Romero, Roberto

    2016-04-01

    'Manual navigation' by the operator is the standard method used to obtain information from two-dimensional and volumetric sonography. Two-dimensional sonography is highly operator dependent and requires extensive training and expertise to assess fetal anatomy properly. Most of the sonographic examination time is devoted to acquisition of images, while 'retrieval' and display of diagnostic planes occurs rapidly (essentially instantaneously). In contrast, volumetric sonography has a rapid acquisition phase, but the retrieval and display of relevant diagnostic planes is often time-consuming, tedious and challenging. We propose the term 'intelligent navigation' to refer to a new method of interrogation of a volume dataset whereby identification and selection of key anatomical landmarks allow the system to: 1) generate a geometrical reconstruction of the organ of interest; and 2) automatically navigate, find, extract and display specific diagnostic planes. This is accomplished using operator-independent algorithms that are both predictable and adaptive. Virtual Intelligent Sonographer Assistance (VIS-Assistance®) is a tool that allows operator-independent sonographic navigation and exploration of the surrounding structures in previously identified diagnostic planes. The advantage of intelligent (over manual) navigation in volumetric sonography is the short time required for both acquisition and retrieval and display of diagnostic planes. Intelligent navigation technology automatically realigns the volume, and reorients and standardizes the anatomical position, so that the fetus and the diagnostic planes are consistently displayed in the same manner each time, regardless of the fetal position or the initial orientation. Automatic labeling of anatomical structures, subject orientation and each of the diagnostic planes is also possible. Intelligent navigation technology can operate on conventional computers, and is not dependent on specific ultrasound platforms or on the

  7. THE ATACAMA COSMOLOGY TELESCOPE: PHYSICAL PROPERTIES OF SUNYAEV-ZEL'DOVICH EFFECT CLUSTERS ON THE CELESTIAL EQUATOR {sup ,}

    Energy Technology Data Exchange (ETDEWEB)

    Menanteau, Felipe; Hughes, John P. [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Sifon, Cristobal; Barrientos, L. Felipe; Duenner, Rolando; Infante, Leopoldo [Departamento de Astronomia y Astrofisica, Facultad de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Battaglia, Nicholas [McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Bond, J. Richard; Hajian, Amir; Hincks, Adam D. [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8 (Canada); Crichton, Devin; Gralla, Megan; Marriage, Tobias A. [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218-2686 (United States); Das, Sudeep [High Energy Physics Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont, IL 60439 (United States); Devlin, Mark J.; Dicker, Simon [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Hasselfield, Matthew [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); Hilton, Matt [Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Durban (South Africa); Kosowsky, Arthur [Physics and Astronomy Department, University of Pittsburgh, 100 Allen Hall, 3941 O' Hara Street, Pittsburgh, PA 15260 (United States); Marsden, Danica [Department of Physics, University of California Santa Barbara, CA 93106 (United States); and others

    2013-03-01

    We present the optical and X-ray properties of 68 galaxy clusters selected via the Sunyaev-Zel'dovich (SZ) effect at 148 GHz by the Atacama Cosmology Telescope (ACT). Our sample, from an area of 504 deg{sup 2} centered on the celestial equator, is divided into two regions. The main region uses 270 deg{sup 2} of the ACT survey that overlaps with the co-added ugriz imaging from the Sloan Digital Sky Survey (SDSS) over Stripe 82 plus additional near-infrared pointed observations with the Apache Point Observatory 3.5 m telescope. We confirm a total of 49 clusters to z Almost-Equal-To 1.3, of which 22 (all at z > 0.55) are new discoveries. For the second region, the regular-depth SDSS imaging allows us to confirm 19 more clusters up to z Almost-Equal-To 0.7, of which 10 systems are new. We present the optical richness, photometric redshifts, and separation between the SZ position and the brightest cluster galaxy (BCG). We find no significant offset between the cluster SZ centroid and BCG location and a weak correlation between optical richness and SZ-derived mass. We also present X-ray fluxes and luminosities from the ROSAT All Sky Survey which confirm that this is a massive sample. One of the newly discovered clusters, ACT-CL J0044.4+0113 at z = 1.1 (photometric), has an integrated XMM-Newton X-ray temperature of kT{sub X} = 7.9 {+-} 1.0 keV and combined mass of M {sub 200a} = 8.2{sup +3.3} {sub -2.5} Multiplication-Sign 10{sup 14} h {sup -1} {sub 70} M {sub Sun }, placing it among the most massive and X-ray-hot clusters known at redshifts beyond z = 1. We also highlight the optically rich cluster ACT-CL J2327.4-0204 (RCS2 2327) at z = 0.705 (spectroscopic) as the most significant detection of the whole equatorial sample with a Chandra-derived mass of M {sub 200a} = 1.9{sup +0.6} {sub -0.4} Multiplication-Sign 10{sup 15} h {sup -1} {sub 70} M {sub Sun }, placing it in the ranks of the most massive known clusters like El Gordo and the Bullet Cluster.

  8. Navigation Architecture for a Space Mobile Network

    Science.gov (United States)

    Valdez, Jennifer E.; Ashman, Benjamin; Gramling, Cheryl; Heckler, Gregory W.; Carpenter, Russell

    2016-01-01

    The Tracking and Data Relay Satellite System (TDRSS) Augmentation Service for Satellites (TASS) is a proposed beacon service to provide a global, space based GPS augmentation service based on the NASA Global Differential GPS (GDGPS) System. The TASS signal will be tied to the GPS time system and usable as an additional ranging and Doppler radiometric source. Additionally, it will provide data vital to autonomous navigation in the near Earth regime, including space weather information, TDRS ephemerides, Earth Orientation Parameters (EOP), and forward commanding capability. TASS benefits include enhancing situational awareness, enabling increased autonomy, and providing near real-time command access for user platforms. As NASA Headquarters' Space Communication and Navigation Office (SCaN) begins to move away from a centralized network architecture and towards a Space Mobile Network (SMN) that allows for user initiated services, autonomous navigation will be a key part of such a system. This paper explores how a TASS beacon service enables the Space Mobile Networking paradigm, what a typical user platform would require, and provides an in-depth analysis of several navigation scenarios and operations concepts. This paper provides an overview of the TASS beacon and its role within the SMN and user community. Supporting navigation analysis is presented for two user mission scenarios: an Earth observing spacecraft in low earth orbit (LEO), and a highly elliptical spacecraft in a lunar resonance orbit. These diverse flight scenarios indicate the breadth of applicability of the TASS beacon for upcoming users within the current network architecture and in the SMN.

  9. Celestial Phenomena and Royal Glory: The Painted Ceiling in Ehrenstrahlsalongen by David Klöcker Ehrenstrahl at Drottningholm Palace in Sweden

    Science.gov (United States)

    Söderlund, I. E.

    2011-06-01

    This paper explores the relationship of astronomical phenomena and the painted ceiling The Glorious Deeds of Swedish Kings executed around 1694-1696 by the Swedish court painter David Klöcker Ehrenstrahl in the Royal manor Drottningholm, outside Stockholm. The central theme of the painting is how "Reputation" brings the renown of the valour of the Swedish kings to the stars. When Galileo dedicated the moons of Jupiter to the Medici's he used an already established tradition of likening prominent people to celestial phenomena. This paper explores why motifs related to the stars and heavens was considered to be so suitable in the court context in early modern Europe.

  10. Representing User Navigation in XML Retrieval with Structural Summaries

    DEFF Research Database (Denmark)

    Ali, M. S.; Consens, Mariano P.; Larsen, Birger

    This poster presents a novel way to represent user navigation in XML retrieval using collection statistics from XML summaries. Currently, developing user navigation models in XML retrieval is costly and the models are specific to collected user assessments. We address this problem by proposing...... summary navigation models which describe user navigation in terms of XML summaries. We develop our proposal using assessments collected in the interactive track at INEX 2006. Our preliminary results suggest that summary navigation models can represent user navigation in a way that is e ective...

  11. Airborne gravimetry, altimetry, and GPS navigation errors

    Science.gov (United States)

    Colombo, Oscar L.

    1992-01-01

    Proper interpretation of airborne gravimetry and altimetry requires good knowledge of aircraft trajectory. Recent advances in precise navigation with differential GPS have made it possible to measure gravity from the air with accuracies of a few milligals, and to obtain altimeter profiles of terrain or sea surface correct to one decimeter. These developments are opening otherwise inaccessible regions to detailed geophysical mapping. Navigation with GPS presents some problems that grow worse with increasing distance from a fixed receiver: the effect of errors in tropospheric refraction correction, GPS ephemerides, and the coordinates of the fixed receivers. Ionospheric refraction and orbit error complicate ambiguity resolution. Optimal navigation should treat all error sources as unknowns, together with the instantaneous vehicle position. To do so, fast and reliable numerical techniques are needed: efficient and stable Kalman filter-smoother algorithms, together with data compression and, sometimes, the use of simplified dynamics.

  12. Cloud Absorption Radiometer Autonomous Navigation System - CANS

    Science.gov (United States)

    Kahle, Duncan; Gatebe, Charles; McCune, Bill; Hellwig, Dustan

    2013-01-01

    CAR (cloud absorption radiometer) acquires spatial reference data from host aircraft navigation systems. This poses various problems during CAR data reduction, including navigation data format, accuracy of position data, accuracy of airframe inertial data, and navigation data rate. Incorporating its own navigation system, which included GPS (Global Positioning System), roll axis inertia and rates, and three axis acceleration, CANS expedites data reduction and increases the accuracy of the CAR end data product. CANS provides a self-contained navigation system for the CAR, using inertial reference and GPS positional information. The intent of the software application was to correct the sensor with respect to aircraft roll in real time based upon inputs from a precision navigation sensor. In addition, the navigation information (including GPS position), attitude data, and sensor position details are all streamed to a remote system for recording and later analysis. CANS comprises a commercially available inertial navigation system with integral GPS capability (Attitude Heading Reference System AHRS) integrated into the CAR support structure and data system. The unit is attached to the bottom of the tripod support structure. The related GPS antenna is located on the P-3 radome immediately above the CAR. The AHRS unit provides a RS-232 data stream containing global position and inertial attitude and velocity data to the CAR, which is recorded concurrently with the CAR data. This independence from aircraft navigation input provides for position and inertial state data that accounts for very small changes in aircraft attitude and position, sensed at the CAR location as opposed to aircraft state sensors typically installed close to the aircraft center of gravity. More accurate positional data enables quicker CAR data reduction with better resolution. The CANS software operates in two modes: initialization/calibration and operational. In the initialization/calibration mode

  13. Active-imaging-based underwater navigation

    Science.gov (United States)

    Monnin, David; Schmitt, Gwenaël.; Fischer, Colin; Laurenzis, Martin; Christnacher, Frank

    2015-10-01

    Global navigation satellite systems (GNSS) are widely used for the localization and the navigation of unmanned and remotely operated vehicles (ROV). In contrast to ground or aerial vehicles, GNSS cannot be employed for autonomous underwater vehicles (AUV) without the use of a communication link to the water surface, since satellite signals cannot be received underwater. However, underwater autonomous navigation is still possible using self-localization methods which determines the relative location of an AUV with respect to a reference location using inertial measurement units (IMU), depth sensors and even sometimes radar or sonar imaging. As an alternative or a complementary solution to common underwater reckoning techniques, we present the first results of a feasibility study of an active-imaging-based localization method which uses a range-gated active-imaging system and can yield radiometric and odometric information even in turbid water.

  14. Mobile Navigation for Sport’s Pilots

    Directory of Open Access Journals (Sweden)

    Dušan Fister

    2013-06-01

    Full Text Available Today, global object-positioning is accomplished very precisely by GPS satellite technology. Access to this information is provided globally by widespread mobile devices with integrated GPS receivers from everywhere also from airplane. This paper presents a mobile device using GPS receiver to be used by mobile navigation for sports pilots. In fact, the mobile navigation is a mobile application running on Android. Thus, the current position of the airplane is indicated on the GoogleMaps and compared with the planned direction of the flight by the pilot. In addition, this mobile application could also serve flight instructors when tracking student pilots by first independent flights. The proposed solution has shown in practice to be the cheapest substitute for expensive professional navigation devices.

  15. Website Optimization through Mining User Navigational Pattern

    CERN Document Server

    Biswal, Biswajit

    2008-01-01

    With the World Wide Web's ubiquity increase and the rapid development of various online businesses, the complexity of web sites grow. The analysis of web user's navigational pattern within a web site can provide useful information for server performance enhancements, restructuring a website and direct marketing in e-commerce etc. In this paper, an algorithm is proposed for mining such navigation patterns. The key insight is that users access information of interest and follow a certain path while navigating a web site. If they don't find it, they would backtrack and choose among the alternate paths till they reach the destination. The point they backtrack is the Intermediate Reference Location. Identifying such Intermediate locations and destinations out of the pattern will be the main endeavor in the rest of this report.

  16. Benchmark Framework for Mobile Robots Navigation Algorithms

    Directory of Open Access Journals (Sweden)

    Nelson David Muñoz-Ceballos

    2014-01-01

    Full Text Available Despite the wide variety of studies and research on mobile robot systems, performance metrics are not often examined. This makes difficult to establish an objective comparison of achievements. In this paper, the navigation of an autonomous mobile robot is evaluated. Several metrics are described. These metrics, collectively, provide an indication of navigation quality, useful for comparing and analyzing navigation algorithms of mobile robots. This method is suggested as an educational tool, which allows the student to optimize the algorithms quality, relating to important aspectsof science, technology and engineering teaching, as energy consumption, optimization and design.

  17. Indoor waypoint navigation via magnetic anomalies.

    Science.gov (United States)

    Riehle, Timothy H; Anderson, Shane M; Lichter, Patrick A; Condon, John P; Sheikh, Suneel I; Hedin, Daniel S

    2011-01-01

    A wide assortment of technologies have been proposed to construct indoor navigation services for the blind and vision impaired. Proximity-based systems and multilateration systems have been successfully demonstrated and employed. Despite the technical success of these technologies, broad adoption has been limited due to their significant infrastructure and maintenance costs. An alternative approach utilizing the indoor magnetic signatures inherent to steel-frame buildings solves the infrastructure cost problem; in effect the existing building is the location system infrastructure. Although magnetic indoor navigation does not require the installation of dedicated hardware, the dedication of resources to produce precise survey maps of magnetic anomalies represents a further barrier to adoption. In the present work an alternative leader-follower form of waypoint-navigation system has been developed that works without surveyed magnetic maps of a site. Instead the wayfarer's magnetometer readings are compared to a pre-recorded magnetic "leader" trace containing magnetic data collected along a route and annotated with waypoint information. The goal of the navigation system is to correlate the follower's magnetometer data with the leader's to trigger audio cues at precise points along the route, thus providing location-based guidance to the user. The system should also provide early indications of off-route conditions. As part of the research effort a smartphone based application was created to record and annotate leader traces with audio and numeric data at waypoints of interest, and algorithms were developed to determine (1) when the follower reaches a waypoint and (2) when the follower goes off-route. A navigation system utilizing this technology would enable a low-cost indoor navigation system capable of replaying audio annotations at precise locations along pre-recorded routes.

  18. Retrosplenial Cortical Neurons Encode Navigational Cues, Trajectories and Reward Locations During Goal Directed Navigation.

    Science.gov (United States)

    Vedder, Lindsey C; Miller, Adam M P; Harrison, Marc B; Smith, David M

    2016-07-29

    The retrosplenial cortex (RSC) plays an important role in memory and spatial navigation. It shares functional similarities with the hippocampus, including the presence of place fields and lesion-induced impairments in spatial navigation, and the RSC is an important source of visual-spatial input to the hippocampus. Recently, the RSC has been the target of intense scrutiny among investigators of human memory and navigation. fMRI and lesion data suggest an RSC role in the ability to use landmarks to navigate to goal locations. However, no direct neurophysiological evidence of encoding navigational cues has been reported so the specific RSC contribution to spatial cognition has been uncertain. To examine this, we trained rats on a T-maze task in which the reward location was explicitly cued by a flashing light and we recorded RSC neurons as the rats learned. We found that RSC neurons rapidly encoded the light cue. Additionally, RSC neurons encoded the reward and its location, and they showed distinct firing patterns along the left and right trajectories to the goal. These responses may provide key information for goal-directed navigation, and the loss of these signals may underlie navigational impairments in subjects with RSC damage.

  19. Evolutionary strategy for achieving autonomous navigation

    Science.gov (United States)

    Gage, Douglas W.

    1999-01-01

    An approach is presented for the evolutionary development of supervised autonomous navigation capabilities for small 'backpackable' ground robots, in the context of a DARPA- sponsored program to provide robotic support to small units of dismounted warfighters. This development approach relies on the implementation of a baseline visual serving navigation capability, including tools to support operator oversight and override, which is then enhanced with semantically referenced commands and a mission scripting structure. As current and future machine perception techniques are able to automatically designate visual serving goal points, this approach should provide a natural evolutionary pathway to higher levels of autonomous operation and reduced requirements for operator intervention.

  20. Navigation: Bat orientation using Earth's magnetic field

    DEFF Research Database (Denmark)

    Holland, Richard A.; Thorup, Kasper; Vonhof, Maarten J.;

    2006-01-01

    Bats famously orientate at night by echolocation 1 , but this works over only a short range, and little is known about how they navigate over longer distances 2 . Here we show that the homing behaviour of Eptesicus fuscus, known as the big brown bat, can be altered by artificially shifting the Ea...... the Earth's magnetic field, indicating that these bats rely on a magnetic compass to return to their home roost. This finding adds to the impressive array of sensory abilities possessed by this animal for navigation in the dark....

  1. Navigation: bat orientation using Earth's magnetic field.

    Science.gov (United States)

    Holland, Richard A; Thorup, Kasper; Vonhof, Maarten J; Cochran, William W; Wikelski, Martin

    2006-12-07

    Bats famously orientate at night by echolocation, but this works over only a short range, and little is known about how they navigate over longer distances. Here we show that the homing behaviour of Eptesicus fuscus, known as the big brown bat, can be altered by artificially shifting the Earth's magnetic field, indicating that these bats rely on a magnetic compass to return to their home roost. This finding adds to the impressive array of sensory abilities possessed by this animal for navigation in the dark.

  2. Navigation and control of an autonomous vehicle

    Energy Technology Data Exchange (ETDEWEB)

    Simon, A.; Soehnitz, I.; Becker, J.C.; Schumacher, W. [Technical Univ. Braunschweig (Germany). Inst. of Control Engineering

    2000-07-01

    This paper describes the fusion of sensor data for the navigation of an autonomous vehicle as well as two lateral control concepts to track the vehicle along a desired path. The fusion of navigation data is based on information provided by multiple object-detecting sensors. The object data is fused to increase the accuracy and to obtain the vehicle's state from the relative movement w.r.t. the objects. The presented lateral control methods are an LQG/H{sub 2}-design and an input-output linearizing algorithm. These control schemes were both implemented on a test vehicle. (orig.)

  3. Diffusive chaos in navigation satellites orbits

    CERN Document Server

    Daquin, J; Tsiganis, K

    2016-01-01

    The navigation satellite constellations in medium-Earth orbit exist in a background of third-body secular resonances stemming from the perturbing gravitational effects of the Moon and the Sun. The resulting chaotic motions, emanating from the overlapping of neighboring resonant harmonics, induce especially strong perturbations on the orbital eccentricity, which can be transported to large values, thereby increasing the collision risk to the constellations and possibly leading to a proliferation of space debris. We show here that this transport is of a diffusive nature and we present representative diffusion maps that are useful in obtaining a global comprehension of the dynamical structure of the navigation satellite orbits.

  4. Method based on artificial excitation of characteristic radiation by an electron beam for remote X-ray spectral elemental analysis of surface rocks on atmosphereless celestial bodies

    Science.gov (United States)

    Kolesnikov, E. K.

    2016-11-01

    This article, like our previous one [1], is devoted to advanced space technology concepts. It evaluates the potential for developing active systems to conduct a remote elemental analysis of surface rocks on an atmosphereless celestial body. The analysis is based on the spectrometry of characteristic X-rays (CXR) artificially excited in the surface soil layer. It has been proposed to use an electron beam injected from aboard a spacecraft orbiting the celestial body (or moving in a flyby trajectory) to excite the CXR elements contained in surface rocks. The focus is on specifying technical requirements to the parameters of payloads for a global mapping of the composition of lunar rocks from aboard of a low-orbiting lunar satellite. This article uses the results obtained in [2], our first study that shows the potential to develop an active system for a remote elemental analysis of lunar surface rocks using the above method. Although there has been interest in our research on the part of leading national academic institutions and space technology developers in the Soviet Union, the studies were discontinued because of the termination of the Soviet lunar program and the completion of the American Apollo program.

  5. Complementary terrain/single beacon-based AUV navigation

    Digital Repository Service at National Institute of Oceanography (India)

    Maurya, P.; Curado, T.F.; António, P.

    This paper describes work done towards the development of advanced geophysical-based navigation systems for autonomous underwater vehicles (AUVs). The specific problem that we tackle is that of combining terrain-aided navigation (TAN) with single-beacon...

  6. LiAISON: Linked, Autonomous Interplanetary Satellite Orbit Navigation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A new navigation technique known as LiAISON (Linked Autonomous Interplanetary Satellite Orbit Navigation) may be used to propel the benefits of GPS to new orbits,...

  7. Psychophysical study of the visual sun location in pictures of cloudy and twilight skies inspired by Viking navigation.

    Science.gov (United States)

    Barta, András; Horváth, Gábor; Meyer-Rochow, Victor Benno

    2005-06-01

    In the late 1960s it was hypothesized that Vikings had been able to navigate the open seas, even when the sun was occluded by clouds or below the sea horizon, by using the angle of polarization of skylight. To detect the direction of skylight polarization, they were thought to have made use of birefringent crystals, called "sun-stones," and a large part of the scientific community still firmly believe that Vikings were capable of polarimetric navigation. However, there are some critics who treat the usefulness of skylight polarization for orientation under partly cloudy or twilight conditions with extreme skepticism. One of their counterarguments has been the assumption that solar positions or solar azimuth directions could be estimated quite accurately by the naked eye, even if the sun was behind clouds or below the sea horizon. Thus under partly cloudy or twilight conditions there might have been no serious need for a polarimetric method to determine the position of the sun. The aim of our study was to test quantitatively the validity of this qualitative counterargument. In our psychophysical laboratory experiments, test subjects were confronted with numerous 180 degrees field-of-view color photographs of partly cloudy skies with the sun occluded by clouds or of twilight skies with the sun below the horizon. The task of the subjects was to guess the position or the azimuth direction of the invisible sun with the naked eye. We calculated means and standard deviations of the estimated solar positions and azimuth angles to characterize the accuracy of the visual sun location. Our data do not support the common belief that the invisible sun can be located quite accurately from the celestial brightness and/or color patterns under cloudy or twilight conditions. Although our results underestimate the accuracy of visual sun location by experienced Viking navigators, the mentioned counterargument cannot be taken seriously as a valid criticism of the theory of the alleged

  8. Spatial abstraction for autonomous robot navigation.

    Science.gov (United States)

    Epstein, Susan L; Aroor, Anoop; Evanusa, Matthew; Sklar, Elizabeth I; Parsons, Simon

    2015-09-01

    Optimal navigation for a simulated robot relies on a detailed map and explicit path planning, an approach problematic for real-world robots that are subject to noise and error. This paper reports on autonomous robots that rely on local spatial perception, learning, and commonsense rationales instead. Despite realistic actuator error, learned spatial abstractions form a model that supports effective travel.

  9. Multimedia for mobile environment: image enhanced navigation

    Science.gov (United States)

    Gautam, Shantanu; Sarkis, Gabi; Tjandranegara, Edwin; Zelkowitz, Evan; Lu, Yung-Hsiang; Delp, Edward J.

    2006-01-01

    As mobile systems (such as laptops and mobile telephones) continue growing, navigation assistance and location-based services are becoming increasingly important. Existing technology allow mobile users to access Internet services (e.g. email and web surfing), simple multimedia services (e.g. music and video clips), and make telephone calls. However, the potential of advanced multimedia services has not been fully developed, especially multimedia for navigation or location based services. At Purdue University, we are developing an image database, known as LAID, in which every image is annotated with its location, compass heading, acquisition time, and weather conditions. LAID can be used to study several types of navigation problems: A mobile user can take an image and transmit the image to the LAID sever. The server compares the image with the images stored in the database to determine where the user is located. We refer to this as the "forward" navigation problem. The second type of problem is to provide a "virtual tour on demand". A user inputs a starting and an ending addresses and LAID retrieves the images along a route that connects the two addresses. This is a generalization of route planning. Our database currently contains over 20000 images and covers approximately 25% of the city of West Lafayette, Indiana.

  10. Apparatus and method of navigating an instrument

    NARCIS (Netherlands)

    Bakker, N.H.; Den Heeten, G.J.

    2004-01-01

    An apparatus to be used with navigating an instrument in a vascular tree of a patient, comprises a patient's examination table, a C-arm, mounted to which is an X-ray source and an image recorder for registering first X-ray images of the patient, obtained by the use of the X-ray source, and a process

  11. Autonomous system for cross-country navigation

    Science.gov (United States)

    Stentz, Anthony; Brumitt, Barry L.; Coulter, R. C.; Kelly, Alonzo

    1993-05-01

    Autonomous cross-country navigation is essential for outdoor robots moving about in unstructured environments. Most existing systems use range sensors to determine the shape of the terrain, plan a trajectory that avoids obstacles, and then drive the trajectory. Performance has been limited by the range and accuracy of sensors, insufficient vehicle-terrain interaction models, and the availability of high-speed computers. As these elements improve, higher- speed navigation on rougher terrain becomes possible. We have developed a software system for autonomous navigation that provides for greater capability. The perception system supports a large braking distance by fusing multiple range images to build a map of the terrain in front of the vehicle. The system identifies range shadows and interpolates undersamples regions to account for rough terrain effects. The motion planner reduces computational complexity by investigating a minimum number of trajectories. Speeds along the trajectory are set to provide for dynamic stability. The entire system was tested in simulation, and a subset of the capability was demonstrated on a real vehicle. Results to date include a continuous 5.1 kilometer run across moderate terrain with obstacles. This paper begins with the applications, prior work, limitations, and current paradigms for autonomous cross-country navigation, and then describes our contribution to the area.

  12. Ground Vehicle Navigation Using Magnetic Field Variation

    Science.gov (United States)

    2012-09-13

    contained magnetometer-based navigation system. Indoor, urban, and canyon environments present challenges for GNSS in terms of limited or poor signal...Aztek sports utility vehicle (SUV), and a 2005 Nissan Altima car were chosen as typical vehicles. Each platform represented a different vehicle type in

  13. Orchard navigation using derivative free Kalman filtering

    DEFF Research Database (Denmark)

    Hansen, Søren; Bayramoglu, Enis; Andersen, Jens Christian

    2011-01-01

    This paper describes the use of derivative free filters for mobile robot localization and navigation in an orchard. The localization algorithm fuses odometry and gyro measurements with line features representing the surrounding fruit trees of the orchard. The line features are created on basis of 2...

  14. 'Outsmarting Traffic, Together': Driving as Social Navigation

    Directory of Open Access Journals (Sweden)

    Sam Hind

    2014-04-01

    Full Text Available The automotive world is evolving. Ten years ago Nigel Thrift (2004: 41 made the claim that the experience of driving was slipping into our 'technological unconscious'. Only recently the New York Times suggested that with the rise of automated driving, standalone navigation tools as we know them would cease to exist, instead being 'fully absorbed into the machine' (Fisher, 2013. But in order to bridge the gap between past and future driving worlds, another technological evolution is emerging. This short, critical piece charts the rise of what has been called 'social navigation' in the industry; the development of digital mapping platforms designed to foster automotive sociality. It makes two provisional points. Firstly, that 'ludic' conceptualisations can shed light on the ongoing reconfiguration of drivers, vehicles, roads and technological aids such as touch-screen satellite navigation platforms. And secondly, that as a result of this, there is a coming-into-being of a new kind of driving politics; a 'casual politicking' centred on an engagement with digital interfaces. We explicate both by turning our attention towards Waze; a social navigation application that encourages users to interact with various driving dynamics.   

  15. A GPS inspired Terrain Referenced Navigation algorithm

    NARCIS (Netherlands)

    Vaman, D.

    2014-01-01

    Terrain Referenced Navigation (TRN) refers to a form of localization in which measurements of distances to the terrain surface are matched with a digital elevation map allowing a vehicle to estimate its own position within the map. The main goal of this dissertation is to improve TRN performance thr

  16. Cameras Improve Navigation for Pilots, Drivers

    Science.gov (United States)

    2012-01-01

    Advanced Scientific Concepts Inc. (ASC), of Santa Barbara, California, received SBIR awards and other funding from the Jet Propulsion Laboratory, Johnson Space Center, and Langley Research Center to develop and refine its 3D flash LIDAR technologies for space applications. Today, ASC's NASA-derived technology is sold to assist with collision avoidance, navigation, and object tracking.

  17. The safety potential of navigation systems.

    NARCIS (Netherlands)

    Oei, H.-l.

    2002-01-01

    This study deals with the possible negative and positive effects of navigation systems on road safety. The literature shows that the human factors side is open for improvement: the design of the menu, possibility of manual programming during driving and shifting the attention of the driver from the

  18. A multimodal interaction system for navigation

    NARCIS (Netherlands)

    Hofs, Dennis; Akker, op den Rieks; Nijholt, Anton; Hondorp, Hendri; Kruijff-Korbayova, I.; Kosny, C.

    2003-01-01

    To help users find their way in a virtual theatre we developed a navigation agent. In natural language dialogue the agent assists users looking for the location of an object or room, and it shows routes between locations. The speech-based dialogue system allows users to ask questions such as “Where

  19. What We Can Learn from Navigation Exercises.

    Science.gov (United States)

    Covell, Geoff

    1992-01-01

    Navigation exercises in the outdoors involve interactive team skills; individual assessment of self-confidence, competence, and esteem; and leadership skills. Learning goals include planning, managing a team, handling information, allocating individual objectives, making decisions, and attending to accuracy. Provides facilitators with instructions…

  20. Navigation system for a smart wheelchair

    Institute of Scientific and Technical Information of China (English)

    BONCI Andrea; LONGHI Sauro; MONTERI(U) Andrea; VACCARINI Massimo

    2005-01-01

    Recent results on the development of a navigation system for a smart wheelchair are presented in this paper. In order to reduce the development cost, a modular solution is designed by using commercial and low cost devices. The functionalities of the tracking control system are described. Experimental results of the proposed assistive system are also presented and discussed.

  1. Tactual Strip Maps as Navigational Aids.

    Science.gov (United States)

    Golledge, R. G.

    1991-01-01

    This article reviews the history and use of tactual maps by blind and visually impaired travelers. It discusses textual patterns, symbols, and graphics; differences between conventional geographic-cartographic maps and strip maps used as navigational aids; and current advances, including disposable, quick-to-produce, and easy-to-update strip maps.…

  2. Mobile Screens: The Visual Regime of Navigation

    NARCIS (Netherlands)

    Verhoeff, N.

    2012-01-01

    In this book on screen media, space, and mobility I compare synchronically, as well as diachronically, diverse and variegated screen media - their technologies and practices – as sites for virtual mobility and navigation. Mobility as a central trope can be found on the multiple levels that are inves

  3. Spatial Navigation in Preclinical Alzheimer's Disease

    Science.gov (United States)

    Allison, Samantha L.; Fagan, Anne M.; Morris, John C.; Head, Denise

    2016-01-01

    Although several previous studies have demonstrated navigational deficits in early-stage symptomatic Alzheimer's disease (AD), navigational abilities in preclinical AD have not been examined. The present investigation examined the effects of preclinical AD and early-stage symptomatic AD on spatial navigation performance. Performance on tasks of wayfinding and route learning in a virtual reality environment were examined. Comparisons were made across the following three groups: Clinically normal without preclinical AD (n = 42), clinically normal with preclinical AD (n = 13), and early-stage symptomatic AD (n = 16) groups. Preclinical AD was defined based on cerebrospinal fluid Aβ42 levels below 500 pg/ml. Preclinical AD was associated with deficits in the use of a wayfinding strategy, but not a route learning strategy. Moreover, post-hoc analyses indicated that wayfinding performance had moderate sensitivity and specificity. Results also confirmed early-stage symptomatic AD-related deficits in the use of both wayfinding and route learning strategies. The results of this study suggest that aspects of spatial navigation may be particularly sensitive at detecting the earliest cognitive deficits of AD. PMID:26967209

  4. Return Velocity and Drawdown in Navigable Waterways

    Science.gov (United States)

    1996-08-01

    I2) DRIGHT -((2 * ARIGHT) /BRIGHT) -(ONAX /2) BRRAT =BRIGHT * RAT DLRAT -DLEFT * RAT I)RRAT -DRIGHT * RAT MNAT - DRAX * RAT SELECT CASE DMRAT CASE IS...M., and Chen, Y. H. (1988). "Physical impacts of navigation on the Upper Mississippi River Systems," U.S. Army Engineer District, St. Louis , St. Louis

  5. Navigating the Bio-Politics of Childhood

    Science.gov (United States)

    Lee, Nick; Motzkau, Johanna

    2011-01-01

    Childhood research has long shared a bio-political terrain with state agencies in which children figure primarily as "human futures". In the 20th century bio-social dualism helped to make that terrain navigable by researchers, but, as life processes increasingly become key sites of bio-political action, bio-social dualism is becoming…

  6. Navigation services of the Mars Network

    Science.gov (United States)

    Ely, T. A.; Guinn, J.; Quintanilla, E.

    2003-01-01

    The Mars Network provides proximity based communications and navigation services to support Mars exploration. The network will be comprised of science orbiters with a MN relay transceiver, and potentially, dedicated telecommunication orbiters. The common MN transceiver, called Electra, is currently in deployment, and is being designed for both communications and radiometric tracking.

  7. Non-Navigable Streams and Wetlands

    Science.gov (United States)

    In 2006, the US Supreme Court addressed jurisdiction of non-navigable waters and adjacent wetlands (NSW) under the Clean Water Act (CWA). The Rapanos decision resulted in two criteria for determining CWA jurisdiction of NSWs: their hydrological permanence and whether they have ...

  8. Navigated Waterways of Louisiana, Geographic NAD83, LOSCO (1999) [navigated_waterways_LOSCO_1999

    Data.gov (United States)

    Louisiana Geographic Information Center — This is a line dataset of navigated waterways fitting the LOSCO definition: it has been traveled by vessels transporting 10,000 gallons of oil or fuel as determined...

  9. Vision/INS Integrated Navigation System for Poor Vision Navigation Environments

    Directory of Open Access Journals (Sweden)

    Youngsun Kim

    2016-10-01

    Full Text Available In order to improve the performance of an inertial navigation system, many aiding sensors can be used. Among these aiding sensors, a vision sensor is of particular note due to its benefits in terms of weight, cost, and power consumption. This paper proposes an inertial and vision integrated navigation method for poor vision navigation environments. The proposed method uses focal plane measurements of landmarks in order to provide position, velocity and attitude outputs even when the number of landmarks on the focal plane is not enough for navigation. In order to verify the proposed method, computer simulations and van tests are carried out. The results show that the proposed method gives accurate and reliable position, velocity and attitude outputs when the number of landmarks is insufficient.

  10. Lunar Navigator - A Miniature, Fully Autonomous, Lunar Navigation, Surveyor, and Range Finder System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Microcosm will use existing hardware and software from related programs to create a prototype Lunar Navigation Sensor (LNS) early in Phase II, such that most of the...

  11. Wayfinding and Navigation for People with Disabilities Using Social Navigation Networks

    Directory of Open Access Journals (Sweden)

    Hassan A. Karimi

    2014-10-01

    Full Text Available To achieve safe and independent mobility, people usually depend on published information, prior experience, the knowledge of others, and/or technology to navigate unfamiliar outdoor and indoor environments. Today, due to advances in various technologies, wayfinding and navigation systems and services are commonplace and are accessible on desktop, laptop, and mobile devices. However, despite their popularity and widespread use, current wayfinding and navigation solutions often fail to address the needs of people with disabilities (PWDs. We argue that these shortcomings are primarily due to the ubiquity of the compute-centric approach adopted in these systems and services, where they do not benefit from the experience-centric approach. We propose that following a hybrid approach of combining experience-centric and compute-centric methods will overcome the shortcomings of current wayfinding and navigation solutions for PWDs.

  12. Lunar Navigator - A Miniature, Fully Autonomous, Lunar Navigation, Surveyor, and Range Finder System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Microcosm proposes to design and develop a fully autonomous Lunar Navigator based on our MicroMak miniature star sensor and a gravity gradiometer similar to one on a...

  13. A New Navigation Strategy in Hypermedia Integral Ware Authoring System

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    After analyzing the general navigation mechanisms and discussing the knowledge point card linking model which is the base of the navigation mechanism used in the Hypermedia Integral ware Authoring System(HIAS), the paper presents a new navigation strategy in HIAS. And the application trend of HIAS is discussed at last.

  14. Private Graphs - Access Rights on Graphs for Seamless Navigation

    Science.gov (United States)

    Dorner, W.; Hau, F.; Pagany, R.

    2016-06-01

    After the success of GNSS (Global Navigational Satellite Systems) and navigation services for public streets, indoor seems to be the next big development in navigational services, relying on RTLS - Real Time Locating Services (e.g. WIFI) and allowing seamless navigation. In contrast to navigation and routing services on public streets, seamless navigation will cause an additional challenge: how to make routing data accessible to defined users or restrict access rights for defined areas or only to parts of the graph to a defined user group? The paper will present case studies and data from literature, where seamless and especially indoor navigation solutions are presented (hospitals, industrial complexes, building sites), but the problem of restricted access rights was only touched from a real world, but not a technical perspective. The analysis of case studies will show, that the objective of navigation and the different target groups for navigation solutions will demand well defined access rights and require solutions, how to make only parts of a graph to a user or application available to solve a navigational task. The paper will therefore introduce the concept of private graphs, which is defined as a graph for navigational purposes covering the street, road or floor network of an area behind a public street and suggest different approaches how to make graph data for navigational purposes available considering access rights and data protection, privacy and security issues as well.

  15. Time and Motion Study of a Community Patient Navigator

    Directory of Open Access Journals (Sweden)

    Sara S. Phillips

    2014-04-01

    Full Text Available Research on patient navigation has focused on validating the utility of navigators by defining their roles and analyzing their effects on patient outcomes, patient satisfaction, and cost effectiveness. Patient navigators are increasingly used outside the research context, and their roles without research responsibilities may look very different. This pilot study captured the activities of a community patient navigator for uninsured women with a positive screening test for breast cancer, using a time and motion approach over a period of three days. We followed the actions of this navigator minute by minute to assess the relative ratios of actions performed and to identify areas for time efficiency improvement to increase direct time with patients. This novel approach depicts the duties of a community patient navigator no longer fettered by navigation logs, research team meetings, surveys, and the consent process. We found that the community patient navigator was able to spend more time with patients in the clinical context relative to performing paperwork or logging communication with patients as a result of her lack of research responsibilities. By illuminating how community patient navigation functions as separate from the research setting, our results will inform future hiring and training of community patient navigators, system design and operations for improving the efficiency and efficacy of navigators, and our understanding of what community patient navigators do in the absence of research responsibilities.

  16. Adaptive Landmark-Based Navigation System Using Learning Techniques

    DEFF Research Database (Denmark)

    Zeidan, Bassel; Dasgupta, Sakyasingha; Wörgötter, Florentin

    2014-01-01

    The goal-directed navigational ability of animals is an essential prerequisite for them to survive. They can learn to navigate to a distal goal in a complex environment. During this long-distance navigation, they exploit environmental features, like landmarks, to guide them towards their goal...

  17. 14 CFR 121.305 - Flight and navigational equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Flight and navigational equipment. 121.305... Flight and navigational equipment. No person may operate an airplane unless it is equipped with the following flight and navigational instruments and equipment: (a) An airspeed indicating system with...

  18. 75 FR 8390 - St. Croix River Aids to Navigation

    Science.gov (United States)

    2010-02-24

    ... SECURITY Coast Guard St. Croix River Aids to Navigation AGENCY: Coast Guard, DHS. ACTION: Notice of public... the aids to navigation in the St. Croix River. DATES: A public meeting will be held on Tuesday, March... review the current Aids to Navigation system on the St. Croix River and discuss concerns and...

  19. Automatic land vehicle navigation using road map data

    Energy Technology Data Exchange (ETDEWEB)

    Schindwolf, R.

    1984-06-01

    A land navigation system has been developed that provides accurate navigation data while it is traveling on mapped roads. The system is autonomous and consists of a simple dead-reckoning navigator that is updated with stored road map data. Simulation and preliminary test results indicate that accuracies on the order of 50 feet can be achieved. Accuracy is independent of time.

  20. Field-based validation of a tactile navigation device

    NARCIS (Netherlands)

    Elliott, L.R.; Erp, J. van; Redden, E.S.; Duistermaat, M.

    2010-01-01

    In this paper, we present three field-based evaluations of a tactile land navigation system. In Experiment 1, we transition from a laboratory setting to rugged terrain used to train US Army soldier land navigation. Navigation in this challenging terrain requires careful attention to one's surroundin

  1. Benefits of multisensory presentation on perception, memory and navigation

    NARCIS (Netherlands)

    Philippi, T.G.

    2012-01-01

    Navigation is the process of planning and following routes to travel from the current location to a target location. In comparison with real world navigation, we have considerable difficulty with navigation in virtual environments. An important cause is that less information is presented in a virtua

  2. PRIVATE GRAPHS – ACCESS RIGHTS ON GRAPHS FOR SEAMLESS NAVIGATION

    Directory of Open Access Journals (Sweden)

    W. Dorner

    2016-06-01

    Full Text Available After the success of GNSS (Global Navigational Satellite Systems and navigation services for public streets, indoor seems to be the next big development in navigational services, relying on RTLS – Real Time Locating Services (e.g. WIFI and allowing seamless navigation. In contrast to navigation and routing services on public streets, seamless navigation will cause an additional challenge: how to make routing data accessible to defined users or restrict access rights for defined areas or only to parts of the graph to a defined user group? The paper will present case studies and data from literature, where seamless and especially indoor navigation solutions are presented (hospitals, industrial complexes, building sites, but the problem of restricted access rights was only touched from a real world, but not a technical perspective. The analysis of case studies will show, that the objective of navigation and the different target groups for navigation solutions will demand well defined access rights and require solutions, how to make only parts of a graph to a user or application available to solve a navigational task. The paper will therefore introduce the concept of private graphs, which is defined as a graph for navigational purposes covering the street, road or floor network of an area behind a public street and suggest different approaches how to make graph data for navigational purposes available considering access rights and data protection, privacy and security issues as well.

  3. 47 CFR 22.365 - Antenna structures; air navigation safety.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Antenna structures; air navigation safety. 22... Antenna structures; air navigation safety. Licensees that own their antenna structures must not allow these antenna structures to become a hazard to air navigation. In general, antenna structure owners...

  4. Evaluation of navigation interfaces in virtual environments

    Science.gov (United States)

    Mestre, Daniel R.

    2014-02-01

    When users are immersed in cave-like virtual reality systems, navigational interfaces have to be used when the size of the virtual environment becomes larger than the physical extent of the cave floor. However, using navigation interfaces, physically static users experience self-motion (visually-induced vection). As a consequence, sensorial incoherence between vision (indicating self-motion) and other proprioceptive inputs (indicating immobility) can make them feel dizzy and disoriented. We tested, in two experimental studies, different locomotion interfaces. The objective was twofold: testing spatial learning and cybersickness. In a first experiment, using first-person navigation with a flystick ®, we tested the effect of sensorial aids, a spatialized sound or guiding arrows on the ground, attracting the user toward the goal of the navigation task. Results revealed that sensorial aids tended to impact negatively spatial learning. Moreover, subjects reported significant levels of cybersickness. In a second experiment, we tested whether such negative effects could be due to poorly controlled rotational motion during simulated self-motion. Subjects used a gamepad, in which rotational and translational displacements were independently controlled by two joysticks. Furthermore, we tested first- versus third-person navigation. No significant difference was observed between these two conditions. Overall, cybersickness tended to be lower, as compared to experiment 1, but the difference was not significant. Future research should evaluate further the hypothesis of the role of passively perceived optical flow in cybersickness, but manipulating the virtual environment'sperrot structure. It also seems that video-gaming experience might be involved in the user's sensitivity to cybersickness.

  5. 33 CFR 149.505 - What are the general requirements for aids to navigation?

    Science.gov (United States)

    2010-07-01

    ... for aids to navigation? 149.505 Section 149.505 Navigation and Navigable Waters COAST GUARD... EQUIPMENT Aids to Navigation General § 149.505 What are the general requirements for aids to navigation? The following requirements apply to navigation aids under this subpart: (a) Section 66.01-5 of this chapter,...

  6. 33 CFR 207.470 - Sturgeon Bay and Lake Michigan Ship Canal, Wis.; use and navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Sturgeon Bay and Lake Michigan Ship Canal, Wis.; use and navigation. 207.470 Section 207.470 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS § 207.470 Sturgeon Bay and Lake Michigan Ship Canal, Wis.; use...

  7. 33 CFR 117.458 - Inner Harbor Navigation Canal, New Orleans.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Inner Harbor Navigation Canal, New Orleans. 117.458 Section 117.458 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Louisiana § 117.458 Inner Harbor Navigation Canal, New Orleans. (a)...

  8. 33 CFR 162.35 - Channel of Christina River, Del.; navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Channel of Christina River, Del.; navigation. 162.35 Section 162.35 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY INLAND WATERWAYS NAVIGATION REGULATIONS § 162.35 Channel...

  9. 33 CFR 209.180 - Temporary closure of waterway to navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Temporary closure of waterway to navigation. 209.180 Section 209.180 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE... navigation. (a) When an application is received for the temporary closure of a waterway for the...

  10. 33 CFR 162.30 - Channel of Tuckerton Creek, N.J.; navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Channel of Tuckerton Creek, N.J.; navigation. 162.30 Section 162.30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY INLAND WATERWAYS NAVIGATION REGULATIONS § 162.30 Channel...

  11. Science Benefits of Onboard Spacecraft Navigation

    Science.gov (United States)

    Cangahuala, Al; Bhaskaran, Shyam; Owen, Bill

    2012-01-01

    Primitive bodies (asteroids and comets), which have remained relatively unaltered since their formation, are important targets for scientific missions that seek to understand the evolution of the solar system. Often the first step is to fly by these bodies with robotic spacecraft. The key to maximizing data returns from these flybys is to determine the spacecraft trajectory relative to the target body-in short, navigate the spacecraft- with sufficient accuracy so that the target is guaranteed to be in the instruments' field of view. The most powerful navigation data in these scenarios are images taken by the spacecraft of the target against a known star field (onboard astrometry). Traditionally, the relative trajectory of the spacecraft must be estimated hours to days in advance using images collected by the spacecraft. This is because of (1)!the long round-trip light times between the spacecraft and the Earth and (2)!the time needed to downlink and process navigation data on the ground, make decisions based on the result, and build and uplink instrument pointing sequences from the results. The light time and processing time compromise navigation accuracy considerably, because there is not enough time to use more accurate data collected closer to the target-such data are more accurate because the angular capability of the onboard astrometry is essentially constant as the distance to the target decreases, resulting in better "plane-of- sky" knowledge of the target. Excellent examples of these timing limitations are high-speed comet encounters. Comets are difficult to observe up close; their orbits often limit scientists to brief, rapid flybys, and their coma further restricts viewers from seeing the nucleus in any detail, unless they can view the nucleus at close range. Comet nuclei details are typically discernable for much shorter durations than the roundtrip light time to Earth, so robotic spacecraft must be able to perform onboard navigation. This onboard

  12. Indoor inertial navigation application for smartphones with Android

    Science.gov (United States)

    Kamiński, Ł.; Tarapata, G.

    2015-09-01

    Inertial navigation is widely used by the military, in logistics and sailing. In mobile devices, inertial sensors are mostly used as a support for GPS and Wi-Fi-based navigation systems. Inertial-based navigation might prove useful on mobile devices running Android OS. At present, in spite of the accelerometer sensor's precision having been greatly improved, as well as the devices' computing power continuously rising, inertial navigation's precision still suffers. For smartphones, the key solution seems to be the usage of sensor fusion and signal smart filtering, both discussed in this paper. The paper also describes implementation of inertial navigation in Android devices, their analysis as well as test results.

  13. An integrated GPS/DR navigation system for AUV

    Institute of Scientific and Technical Information of China (English)

    PANG Yong-jie; SUN Yu-shan; GAN Yong; WAN Lei

    2006-01-01

    GPS/Dead-reckoning navigation system for autonomous underwater vehicle (AUV) is introduced, which includes navigation overall architecture, hardware and software structure.Dead-reckoning theory is presented in details. And the strong tracking Kalman filter and Singer model are applied to handle the imprecise navigation mode, which can improve the navigation system's precision and reliability. Finally, the sea experiments which include autonomous search mission in an unknown area and long distance motion are conducted to demonstrate the reliability and feasibility of the navigation system.

  14. Situation awareness and driving performance in a simulated navigation task.

    Science.gov (United States)

    Ma, R; Kaber, D B

    2007-08-01

    The objective of this study was to identify task and vehicle factors that may affect driver situation awareness (SA) and its relationship to performance, particularly in strategic (navigation) tasks. An experiment was conducted to assess the effects of in-vehicle navigation aids and reliability on driver SA and performance in a simulated navigation task. A total of 20 participants drove a virtual car and navigated a large virtual suburb. They were required to follow traffic signs and navigation directions from either a human aid via a mobile phone or an automated aid presented on a laptop. The navigation aids operated under three different levels of information reliability (100%, 80% and 60%). A control condition was used in which each aid presented a telemarketing survey and participants navigated using a map. Results revealed perfect navigation information generally improved driver SA and performance compared to unreliable navigation information and the control condition (task-irrelevant information). In-vehicle automation appears to mediate the relationship of driver SA to performance in terms of operational and strategic (navigation) behaviours. The findings of this work support consideration of driver SA in the design of future vehicle automation for navigation tasks.

  15. Design and implementation of small navigation system on land vehicle

    Science.gov (United States)

    Ma, Shuaiqi

    2013-03-01

    This paper is focused on the problem of frame loss and truncation on multi-channel universal asynchronous receiver transmitter (UART) embedded in Integrated Navigation Systems, and it contains attitude heading reference system (AHRS) and global positioning system (GPS). An advanced design based on FPGA and ARM processor is discussed in this paper, in which FPGA would be used to coordinate with each logic modules, expand UART for GPS and AHRS, resolve navigation information, and save specify data to SD card, which can reduce the delay in data receiving and resolving, while ARM is applied in the area of parameters estimation and navigation algorithms. The experiment results show that this navigation system can use UART to receive, resolve data frames and save data while ARM execute parameter estimation and navigation algorithms in real time. This integrated navigation can effectively avoid the phenomenon of data frame loss or truncation in UART receiving, and can improve the navigation precision.

  16. An excellent navigation system and experience in craniomaxillofacial navigation surgery: a double-center study.

    Science.gov (United States)

    Dai, Jiewen; Wu, Jinyang; Wang, Xudong; Yang, Xudong; Wu, Yunong; Xu, Bing; Shi, Jun; Yu, Hongbo; Cai, Min; Zhang, Wenbin; Zhang, Lei; Sun, Hao; Shen, Guofang; Zhang, Shilei

    2016-06-16

    Numerous problems regarding craniomaxillofacial navigation surgery are not well understood. In this study, we performed a double-center clinical study to quantitatively evaluate the characteristics of our navigation system and experience in craniomaxillofacial navigation surgery. Fifty-six patients with craniomaxillofacial disease were included and randomly divided into experimental (using our AccuNavi-A system) and control (using Strker system) groups to compare the surgical effects. The results revealed that the average pre-operative planning time was 32.32 mins vs 29.74 mins between the experimental and control group, respectively (p > 0.05). The average operative time was 295.61 mins vs 233.56 mins (p > 0.05). The point registration orientation accuracy was 0.83 mm vs 0.92 mm. The maximal average preoperative navigation orientation accuracy was 1.03 mm vs 1.17 mm. The maximal average persistent navigation orientation accuracy was 1.15 mm vs 0.09 mm. The maximal average navigation orientation accuracy after registration recovery was 1.15 mm vs 1.39 mm between the experimental and control group. All patients healed, and their function and profile improved. These findings demonstrate that although surgeons should consider the patients' time and monetary costs, our qualified navigation surgery system and experience could offer an accurate guide during a variety of craniomaxillofacial surgeries.

  17. Reactive navigational controller for autonomous mobile robots

    Science.gov (United States)

    Hawkins, Scott

    1993-12-01

    Autonomous mobile robots must respond to external challenges and threats in real time. One way to satisfy this requirement is to use a fast low level intelligence to react to local environment changes. A fast reactive controller has been implemented which performs the task of real time local navigation by integrating primitive elements of perception, planning, and control. Competing achievement and constraint behaviors are used to allow abstract qualitative specification of navigation goals. An interface is provided to allow a higher level deliberative intelligence with a more global perspective to set local goals for the reactive controller. The reactive controller's simplistic strategies may not always succeed, so a means to monitor and redirect the reactive controller is provided.

  18. Visual Navigation of Complex Information Spaces

    Directory of Open Access Journals (Sweden)

    Sarah North

    1995-11-01

    Full Text Available The authors lay the foundation for the introduction of visual navigation aid to assist computer users in direct manipulation of the complex information spaces. By exploring present research on scientific data visualisation and creating a case for improved information visualisation tools, they introduce the design of an improved information visualisation interface utilizing dynamic slider, called Visual-X, incorporating icons with bindable attributes (glyphs. Exploring the improvement that these data visualisations, make to a computing environment, the authors conduct an experiment to compare the performance of subjects who use traditional interfaces and Visual-X. Methodology is presented and conclusions reveal that the use of Visual-X appears to be a promising approach in providing users with a navigation tool that does not overload their cognitive processes.

  19. Automatic document navigation for digital content remastering

    Science.gov (United States)

    Lin, Xiaofan; Simske, Steven J.

    2003-12-01

    This paper presents a novel method of automatically adding navigation capabilities to re-mastered electronic books. We first analyze the need for a generic and robust system to automatically construct navigation links into re-mastered books. We then introduce the core algorithm based on text matching for building the links. The proposed method utilizes the tree-structured dictionary and directional graph of the table of contents to efficiently conduct the text matching. Information fusion further increases the robustness of the algorithm. The experimental results on the MIT Press digital library project are discussed and the key functional features of the system are illustrated. We have also investigated how the quality of the OCR engine affects the linking algorithm. In addition, the analogy between this work and Web link mining has been pointed out.

  20. Navigation simulator for the Space Tug vehicle

    Science.gov (United States)

    Colburn, B. K.; Boland, J. S., III; Peters, E. G.

    1977-01-01

    A general simulation program (GSP) for state estimation of a nonlinear space vehicle flight navigation system is developed and used as a basis for evaluating the performance of a Space Tug navigation system. An explanation of the iterative guidance mode (IGM) guidance law, derivation of the dynamics, coordinate frames and state estimation routines are given in order to clarify the assumptions and approximations made. A number of simulation and analytical studies are used to demonstrate the operation of the Tug system. Included in the simulation studies are (1) initial offset vector parameter study; (2) propagation time vs accuracy; (3) measurement noise parametric study and (4) reduction in computational burden of an on-board implementable scheme. From the results of these studies, conclusions and recommendations concerning future areas of practical and theoretical work are presented.

  1. Optical Navigation for the Orion Vehicle

    Science.gov (United States)

    Crain, Timothy; Getchius, Joel; D'Souza, Christopher

    2008-01-01

    The Orion vehicle is being designed to provide nominal crew transport to the lunar transportation stack in low Earth orbit, crew abort prior during transit to the moon, and crew return to Earth once lunar orbit is achieved. One of the design requirements levied on the Orion vehicle is the ability to return to the vehicle and crew to Earth in the case of loss of communications and command with the Mission Control Center. Central to fulfilling this requirement, is the ability of Orion to navigate autonomously. In low-Earth orbit, this may be solved with the use of GPS, but in cis-lunar and lunar orbit this requires optical navigation. This paper documents the preliminary analyses performed by members of the Orion Orbit GN&C System team.

  2. Design of Evolvable Hardware for Robotic Navigation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents an integrated on-line learning system toevolve programmabl e logic array (PLA) controllers for navigating an autonomous robot in a two-dime n sional environment. The integrated on-line learning system consists of two lear n ing modules: one is the module of reinforcement learning based on temporal-diff e rence learning based on genetic algorithms, and the other is the module of evolu tionary learning based on genetic algorithms. The control rules extracted from t he module of reinforcement learning can be used as input to the module of evolut ionary learning, and quickly implemented by the PLA through on-line evolution. T he on-line evolution has shown promise as a method of learning systems in compl e x environment. The evolved PLA controllers can successfully navigate the robot t o a target in the two-dimensional environment while avoiding collisions with ra ndomly positioned obstacles.

  3. Development of autonomous grasping and navigating robot

    Science.gov (United States)

    Kudoh, Hiroyuki; Fujimoto, Keisuke; Nakayama, Yasuichi

    2015-01-01

    The ability to find and grasp target items in an unknown environment is important for working robots. We developed an autonomous navigating and grasping robot. The operations are locating a requested item, moving to where the item is placed, finding the item on a shelf or table, and picking the item up from the shelf or the table. To achieve these operations, we designed the robot with three functions: an autonomous navigating function that generates a map and a route in an unknown environment, an item position recognizing function, and a grasping function. We tested this robot in an unknown environment. It achieved a series of operations: moving to a destination, recognizing the positions of items on a shelf, picking up an item, placing it on a cart with its hand, and returning to the starting location. The results of this experiment show the applicability of reducing the workforce with robots.

  4. Feeding, Swimming and Navigation of Colonial Microorganisms

    Science.gov (United States)

    Kirkegaard, Julius; Bouillant, Ambre; Marron, Alan; Leptos, Kyriacos; Goldstein, Raymond

    2016-11-01

    Animals are multicellular in nature, but evolved from unicellular organisms. In the closest relatives of animals, the choanoflagellates, the unicellular species Salpincgoeca rosetta has the ability to form colonies, resembling true multicellularity. In this work we use a combination of experiments, theory, and simulations to understand the physical differences that arise from feeding, swimming and navigating as colonies instead of as single cells. We show that the feeding efficiency decreases with colony size for distinct reasons in the small and large Péclet number limits, and we find that swimming as a colony changes the conventional active random walks of microorganism to stochastic helices, but that this does not hinder effective navigation towards chemoattractants.

  5. Robot navigation system using intrinsic evolvable hardware

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Recently there has been great interest in the idea that evolvable system based on the principle of ar tifcial intelligence can be used to continuously and autonomously adapt the behaviour of physically embedded systems such as autonomous mobile robots and intelligent home devices. Meanwhile, we have seen the introduc tion of evolvable hardware(EHW): new integrated electronic circuits that are able to continuously evolve to a dapt the chages in the environment implemented by evolutionary algorithms such as genetic algorithm(GA)and reinforcement learning. This paper concentrates on developing a robotic navigation system whose basic behav iours are obstacle avoidance and light source navigation. The results demonstrate that the intrinsic evolvable hardware system is able to create the stable robotiiuc behaviours as required in the real world instead of the tra ditional hardware systems.

  6. Bio-inspired odor-based navigation

    Science.gov (United States)

    Porter, Maynard J., III; Vasquez, Juan R.

    2006-05-01

    The ability of many insects, especially moths, to locate either food or a member of the opposite sex is an amazing achievement. There are numerous scenarios where having this ability embedded into ground-based or aerial vehicles would be invaluable. This paper presents results from a 3-D computer simulation of an Unmanned Aerial Vehicle (UAV) autonomously tracking a chemical plume to its source. The simulation study includes a simulated dynamic chemical plume, 6-degree of freedom, nonlinear aircraft model, and a bio-inspired navigation algorithm. The emphasis of this paper is the development and analysis of the navigation algorithm. The foundation of this algorithm is a fuzzy controller designed to categorize where in the plume the aircraft is located: coming into the plume, in the plume, exiting the plume, or out of the plume.

  7. Autonomous Rule Based Robot Navigation In Orchards

    DEFF Research Database (Denmark)

    Andersen, Jens Christian; Ravn, Ole; Andersen, Nils Axel

    2010-01-01

    Orchard navigation using sensor-based localization and exible mission management facilitates successful missions independent of the Global Positioning System (GPS). This is especially important while driving between tight tree rows where the GPS coverage is poor. This paper suggests localization ......, obstacle avoidance, path planning and drive control. The system is tested successfully using a Hako 20 kW tractor during autonomous missions in both cherry and apple orchards with mission length of up to 2.3 km including the headland turns.......Orchard navigation using sensor-based localization and exible mission management facilitates successful missions independent of the Global Positioning System (GPS). This is especially important while driving between tight tree rows where the GPS coverage is poor. This paper suggests localization...

  8. Herschel celestial calibration sources: Four large main-belt asteroids as prime flux calibrators for the far-IR/sub-mm range

    CERN Document Server

    Mueller, T G; Nielbock, M; Lim, T; Teyssier, D; Olberg, M; Klaas, U; Linz, H; Altieri, B; Pearson, C; Bendo, G; Vilenius, E

    2013-01-01

    Celestial standards play a major role in observational astrophysics. They are needed to characterise the performance of instruments and are paramount for photometric calibration. During the Herschel Calibration Asteroid Preparatory Programme approximately 50 asteroids have been established as far-IR/sub-mm/mm calibrators for Herschel. The selected asteroids fill the flux gap between the sub-mm/mm calibrators Mars, Uranus and Neptune, and the mid-IR bright calibration stars. All three Herschel instruments observed asteroids for various calibration purposes, including pointing tests, absolute flux calibration, relative spectral response function, observing mode validation, and cross-calibration aspects. Here we present newly established models for the four large and well characterized main-belt asteroids (1) Ceres, (2) Pallas, (4) Vesta, and (21) Lutetia which can be considered as new prime flux calibrators. The relevant object-specific properties (size, shape, spin-properties, albedo, thermal properties) are w...

  9. Generation of trajectories and choice of routes for a passive flyby of a group of celestial bodies moving in Keplerian orbits.

    Science.gov (United States)

    Akhlebininskij, M. Yu.; Konstantinov, M. S.

    1992-05-01

    The problem of generating trajectories for a flyby of several given celestial bodies moving in Keplerian orbits is solved in a new formulation. It is demonstrated that there exist trajectories along which one vehicle can fly by at least three bodies. A theorem asserting the existence of a trajectory for the flyby of three bodies moving in circular orbits of common radius is formulated and probed. The uniqueness of such trajectories is analyzed. An effective numerical method is proposed for generating trajectories for the flyby of three bodies moving in arbitrary elliptical orbits. The possibilities of the method are illustrated with examples. Questions regarding the insertion of the vehicle into the flyby trajectory are not discussed here.

  10. Omega Navigation System Course Book. Volume 2

    Science.gov (United States)

    1994-07-01

    GPS) - 0846 6. PCD ASSIGNMENT: None G.2.3 Hawaii 1. LETTER DESIGNATION: "C" 2. LQCATION: a. Geographic: Haiku Valley, Oahu Island, Hawaii, U.S.A. b...systems, 2-25, 12-27 inductively matching, 3-23 Haiku , 2-3, 2-11 2inertial navigation, 4-39HYDROLANT, 2-29 hard-copy coverage diagrams, 2-33 inertial

  11. Simulation Platform for Vision Aided Inertial Navigation

    Science.gov (United States)

    2014-09-18

    canyons , indoors or underground. It is also possible for a GPS signal to be jammed. This weakness motivates the development of alternate navigation...accelerometer measurements, Taccel. - Velocity random walk due to accelerometer, VRW - Standard deviation of the time-correlated bias for gyro measurements...σgyro. - Time constant of the time-correlated bias for gyro measurements, Tgyro. - Angular random walk due to gyro, ARW 1.2 Simulate different

  12. Navigational Strategies of Migrating Monarch Butterflies

    Science.gov (United States)

    2014-11-10

    plexippus) use a time- compensated sun compass to navigate from eastern North America to their overwintering grounds in central Mexico . We have described... migrants with either antenna painted black (to block light entrainment) and the other painted clear (to permit light entrainment) display...disoriented group flight. Remarkably, when the black- painted antenna is removed, re-flown migrants with a single, clear-painted antenna exhibit proper

  13. Navigation, perception et apprentissage pour la robotique

    OpenAIRE

    Filliat, David

    2011-01-01

    We conducted research mainly in the areas of navigation, perception and learning for mobile robots. These studies, oriented toward a cognitive approach to robotics have the overall goal of allowing robots to adapt to their environment, providing ba- sic primitives such as open space, position, or the presence of objects necessary to choose actions. A large part of this work is inspired by capabilities found in nature, but without trying to reproduce exactly the biological systems inner functi...

  14. Navigation of an underwater industrial autonomous vehicle

    Energy Technology Data Exchange (ETDEWEB)

    Korotchentsev, V.I.; Rozenbaum, A.N.; Deshner, A.I. [Rossijskaya Akademiya Nauk, Vladivostok (Russian Federation). Inst. Avtomatiki i Protsessov Upravleniya

    2000-07-01

    This paper suggests a new approach to solving the problem of navigation of an underwater vehicle using arbitrary seafloor relief data. The known methods of building seafloor acoustic maps are not effective for correction of coordinates in areas of smooth relief and in shallow water. The suggested algorithm allows making maps using acoustic sectional view of the seafloor layers. The sectional view is of various forms in different areas of the smooth relief. (orig.)

  15. Orbital maneuvering vehicle guidance, navigation and control

    Science.gov (United States)

    Huber, W. G.; Finnell, W., III

    1985-01-01

    This paper describes the Orbital Maneuvering Vehicle (OMV) concept and its intended role. It recaps the past activities leading up to the current concept and summarizes the present status and plans. The various types of missions and operating modes required by the OMV are described as the basis of the guidance, navigation and control (GN&C) requirements. The general GN&C problem is outlined with potential hardware solutions.

  16. The onboard control system of "Navigator" platform

    Science.gov (United States)

    Syrov, A. S.; Smirnov, V. V.; Sokolov, V. N.; Iodko, G. S.; Mischikhin, V. V.; Kosobokov, V. N.; Shatskii, M. A.; Dobrynin, D. A.

    2016-12-01

    A brief description of the design concept, structure and performance of the onboard control system (AOCS) of the "Navigator" satellite platform, on the basis of which the spacecraft "Electro-L' and "Spektr-R" are designed, is presented. The test-flight results of the AOCS attitude accuracy are given. Approaches to the further development of the onboard control equipment for advanced spacecraft are determined and presented.

  17. Outdoor autonomous navigation using monocular vision

    OpenAIRE

    Royer, Eric; Bom, Jonathan; Dhome, Michel; Thuilot, Benoît; Lhuillier, Maxime; Marmoiton, Francois

    2005-01-01

    International audience; In this paper, a complete system for outdoor robot navigation is presented. It uses only monocular vision. The robot is first guided on a path by a human. During this learning step, the robot records a video sequence. From this sequence, a three dimensional map of the trajectory and the environment is built. When this map has been computed, the robot is able to follow the same trajectory by itself. Experimental results carried out with an urban electric vehicle are sho...

  18. Multimodal cognitive interface for robot navigation.

    Science.gov (United States)

    Elmogy, Mohammed; Habel, Christopher; Zhang, Jianwei

    2011-02-01

    To build effective interactions between humans and robots, they should have common ground of understanding that creates realistic expectations and forms the basis communications. An emerging approach to doing this is to create cognitive models of human reasoning and behavior selection. We have developed a robot navigation system that uses both spatial language and graphical representation to describe route-based navigation tasks for a mobile robot. Our proposed route instruction language (RIL) is intended as a semi-formal language for instructing the robot to execute a route in an indoor environment. We implemented an instruction interpreter to process the route description and generate its equivalent symbolic and topological map representations. A topological map is generated to describe relationships among features of the environment in a more abstract form without any absolute reference system to treat the ambiguity which can occur when the robot cannot recognize the current landmark. The symbolic and topological map representations are supplied to other system components as an initial path estimation to guide the robot while it plans its navigation task. We conducted some experiments to evaluate the routes which are written by using the RIL instructions.

  19. Lunar Navigation Determination System - LaNDS

    Science.gov (United States)

    Quinn, David; Talabac, Stephen

    2012-01-01

    A portable comprehensive navigational system has been developed that both robotic and human explorers can use to determine their location, attitude, and heading anywhere on the lunar surface independent of external infrastructure (needs no Lunar satellite network, line of sight to the Sun or Earth, etc.). The system combines robust processing power with an extensive topographical database to create a real-time atlas (GIS Geospatial Information System) that is able to autonomously control and monitor both single unmanned rovers and fleets of rovers, as well as science payload stations. The system includes provisions for teleoperation and tele-presence. The system accepts (but does not require) inputs from a wide range of sensors. A means was needed to establish a location when the search is taken deep in a crater (looking for water ice) and out of view of Earth or any other references. A star camera can be employed to determine the user's attitude in menial space and stellar map in body space. A local nadir reference (e.g., an accelerometer that orients the nadir vector in body space) can be used in conjunction with a digital ephemeris and gravity model of the Moon to isolate the latitude, longitude, and azimuth of the user on the surface. That information can be used in conjunction with a Lunar GIS and advanced navigation planning algorithms to aid astronauts (or other assets) to navigate on the Lunar surface.

  20. Ideal proportional navigation for exoatmospheric interception

    Institute of Scientific and Technical Information of China (English)

    Li Kebo; Zhang Taotao; Chen Lei

    2013-01-01

    Ideal proportional navigation (IPN) is a natural choice for exoatmospheric interception for its mighty capture capability and ease of implementation.The closed-form solution of two-dimensional ideal proportional navigation was conducted in previous public literature,whereas the practical interception happens in the three-dimensional space.A novel set of relative dynamic equations is adopted in this paper,which is with the advantage of decoupling relative motion in the instantaneous rotation plane of the line of sight from the rotation of this plane.The dimension-reduced IPN is constructed in this instantaneous plane,which functions as a three-dimensional guidance law.The trajectory features of dimension-reduced IPN are explored,and the capture regions of dimension-reduced IPN with limited acceleration against nonmaneuvering and maneuvering targets are analyzed by using phase plane method.It is proved that the capture capability of IPN is much stronger than true proportional navigation (TPN),no matter the target maneuvers or not.Finally,simulation results indicate that IPN is more effective than TPN in exoatmospheric interception scenarios.

  1. Navigability of interconnected networks under random failures

    Science.gov (United States)

    De Domenico, Manlio; Solé-Ribalta, Albert; Gómez, Sergio; Arenas, Alex

    2014-01-01

    Assessing the navigability of interconnected networks (transporting information, people, or goods) under eventual random failures is of utmost importance to design and protect critical infrastructures. Random walks are a good proxy to determine this navigability, specifically the coverage time of random walks, which is a measure of the dynamical functionality of the network. Here, we introduce the theoretical tools required to describe random walks in interconnected networks accounting for structure and dynamics inherent to real systems. We develop an analytical approach for the covering time of random walks in interconnected networks and compare it with extensive Monte Carlo simulations. Generally speaking, interconnected networks are more resilient to random failures than their individual layers per se, and we are able to quantify this effect. As an application––which we illustrate by considering the public transport of London––we show how the efficiency in exploring the multiplex critically depends on layers’ topology, interconnection strengths, and walk strategy. Our findings are corroborated by data-driven simulations, where the empirical distribution of check-ins and checks-out is considered and passengers travel along fastest paths in a network affected by real disruptions. These findings are fundamental for further development of searching and navigability strategies in real interconnected systems. PMID:24912174

  2. Neurally Encoding Time for Olfactory Navigation.

    Directory of Open Access Journals (Sweden)

    In Jun Park

    2016-01-01

    Full Text Available Accurately encoding time is one of the fundamental challenges faced by the nervous system in mediating behavior. We recently reported that some animals have a specialized population of rhythmically active neurons in their olfactory organs with the potential to peripherally encode temporal information about odor encounters. If these neurons do indeed encode the timing of odor arrivals, it should be possible to demonstrate that this capacity has some functional significance. Here we show how this sensory input can profoundly influence an animal's ability to locate the source of odor cues in realistic turbulent environments-a common task faced by species that rely on olfactory cues for navigation. Using detailed data from a turbulent plume created in the laboratory, we reconstruct the spatiotemporal behavior of a real odor field. We use recurrence theory to show that information about position relative to the source of the odor plume is embedded in the timing between odor pulses. Then, using a parameterized computational model, we show how an animal can use populations of rhythmically active neurons to capture and encode this temporal information in real time, and use it to efficiently navigate to an odor source. Our results demonstrate that the capacity to accurately encode temporal information about sensory cues may be crucial for efficient olfactory navigation. More generally, our results suggest a mechanism for extracting and encoding temporal information from the sensory environment that could have broad utility for neural information processing.

  3. Navigation in Orthognathic Surgery: 3D Accuracy.

    Science.gov (United States)

    Badiali, Giovanni; Roncari, Andrea; Bianchi, Alberto; Taddei, Fulvia; Marchetti, Claudio; Schileo, Enrico

    2015-10-01

    This article aims to determine the absolute accuracy of maxillary repositioning during orthognathic surgery according to simulation-guided navigation, that is, the combination of navigation and three-dimensional (3D) virtual surgery. We retrospectively studied 15 patients treated for asymmetric dentofacial deformities at the Oral and Maxillofacial Surgery Unit of the S.Orsola-Malpighi University Hospital in Bologna, Italy, from January 2010 to January 2012. Patients were scanned with a cone-beam computed tomography before and after surgery. The virtual surgical simulation was realized with a dedicated software and loaded on a navigation system to improve intraoperative reproducibility of the preoperative planning. We analyzed the outcome following two protocols: (1) planning versus postoperative 3D surface analysis; (2) planning versus postoperative point-based analysis. For 3D surface comparison, the mean Hausdorff distance was measured, and median among cases was 0.99 mm. Median reproducibility orthognathic surgery, if compared with the surgical computer-designed project realized with a dedicated software, particularly for the vertical dimension, which is the most challenging to manage.

  4. Magnetic navigation in percutaneous coronary intervention.

    Science.gov (United States)

    Patterson, Mark S; Schotten, Jeroen; van Mieghem, Carlos; Kiemeneij, Ferdinand; Serruys, Patrick W

    2006-12-01

    Magnetic navigation is the use of adjustable magnetic fields to precisely direct wires and equipment for clinical applications. It is a recently developed option that is now available for interventional cardiology. Procedures are based on the production of a three-dimensional reconstruction of the vessel lumen from standard angiographic images. Knowledge of the positions of the table and image intensifier during angiography allows calculation of the vessel coordinates in real space within the patient's chest. The applied magnetic field can be changed at any time to redirect the wire tip in order to improve navigation through complex and tortuous anatomy. The digital information of the coronary reconstruction can be used in further novel ways. Firstly, the integration of multislice computerized tomography images adds information about the path of the previous lumen of chronic total occlusions. Secondly, the computed center-line of the reconstructed vessel can be superimposed onto the live fluoroscopy images as a three-dimensional guide. The combination of improved navigation together with the other available system features may improve time, contrast, and material usage in a range of coronary lesions. Future potential developments include improvements in equipment and software, and potential therapeutic strategies under consideration include the use of equipment to perform remote control procedures, and the integration of the system to improve bone marrow-derived stem cell delivery.

  5. Geomagnetic storm effects on GPS based navigation

    Directory of Open Access Journals (Sweden)

    P. V. S. Rama Rao

    2009-05-01

    Full Text Available The energetic events on the sun, solar wind and subsequent effects on the Earth's geomagnetic field and upper atmosphere (ionosphere comprise space weather. Modern navigation systems that use radio-wave signals, reflecting from or propagating through the ionosphere as a means of determining range or distance, are vulnerable to a variety of effects that can degrade the performance of the navigational systems. In particular, the Global Positioning System (GPS that uses a constellation of earth orbiting satellites are affected due to the space weather phenomena.

    Studies made during two successive geomagnetic storms that occurred during the period from 8 to 12 November 2004, have clearly revealed the adverse affects on the GPS range delay as inferred from the Total Electron Content (TEC measurements made from a chain of seven dual frequency GPS receivers installed in the Indian sector. Significant increases in TEC at the Equatorial Ionization anomaly crest region are observed, resulting in increased range delay during the periods of the storm activity. Further, the storm time rapid changes occurring in TEC resulted in a number of phase slips in the GPS signal compared to those on quiet days. These phase slips often result in the loss of lock of the GPS receivers, similar to those that occur during strong(>10 dB L-band scintillation events, adversely affecting the GPS based navigation.

  6. Formation of planetary systems is in sight now. ; On transformation on Initial solar system as seen from meteorites (On transformation of source celestial bodies). Wakuseikei no keisei ga mietekita. ; Inseki ni miru shoki taiyokei (Shigen botaiten no henka wo megutte)

    Energy Technology Data Exchange (ETDEWEB)

    Tomeoka, K. (The University of Tokyo, Tokyo (Japan). Faculty of Science)

    1992-02-01

    The meteoritic studies using high-resolution transmission electron microscopes are in a process of elucidating the problem as to whether the carbon-based chondrite meteorites regarded as initial chemically are the substance resulted from accumulation of solid particles which have had existed in the solar system nebulae, or whether they have had been subjected to any secondary modification after the accumulation. The initial state of the solar system was inferred through considering the latest research results on transforming actions given to these source celestial bodies. The intervention of the water quality transformation as a result of water actions at temperatures as low as associating no loss in volatile elements has been elucidated from the researches on micro-structures in a substance contained in the carbon-based chondrite. As to at what stage the water quality transformation has taken place, a view that its timing is after the formation of the base celestial bodies is predominant. A consideration was given on what the first celestial body integrated from a solar system nebula was like using a model presenting the transforming actions on the carbon-based chondrite celestial bodies. 11 refs., 4 figs.

  7. Navigation Performance of Global Navigation Satellite Systems in the Space Service Volume

    Science.gov (United States)

    Force, Dale A.

    2013-01-01

    GPS has been used for spacecraft navigation for many years center dot In support of this, the US has committed that future GPS satellites will continue to provide signals in the Space Service Volume center dot NASA is working with international agencies to obtain similar commitments from other providers center dot In support of this effort, I simulated multi-constellation navigation in the Space Service Volume In this presentation, I extend the work to examine the navigational benefits and drawbacks of the new constellations center dot A major benefit is the reduced geometric dilution of precision (GDOP). I show that there is a substantial reduction in GDOP by using all of the GNSS constellations center dot The increased number of GNSS satellites broadcasting does produce mutual interference, raising the noise floor. A near/far signal problem can also occur where a nearby satellite drowns out satellites that are far away. - In these simulations, no major effect was observed Typically, the use of multi-constellation GNSS navigation improves GDOP by a factor of two or more over GPS alone center dot In addition, at the higher altitudes, four satellite solutions can be obtained much more often center dot This show the value of having commitments to provide signals in the Space Service Volume Besides a commitment to provide a minimum signal in the Space Service Volume, detailed signal gain information is useful for mission planning center dot Knowledge of group and phase delay over the pattern would also reduce the navigational uncertainty

  8. Submarine harbor navigation using image data

    Science.gov (United States)

    Stubberud, Stephen C.; Kramer, Kathleen A.

    2017-01-01

    The process of ingress and egress of a United States Navy submarine is a human-intensive process that takes numerous individuals to monitor locations and for hazards. Sailors pass vocal information to bridge where it is processed manually. There is interest in using video imaging of the periscope view to more automatically provide navigation within harbors and other points of ingress and egress. In this paper, video-based navigation is examined as a target-tracking problem. While some image-processing methods claim to provide range information, the moving platform problem and weather concerns, such as fog, reduce the effectiveness of these range estimates. The video-navigation problem then becomes an angle-only tracking problem. Angle-only tracking is known to be fraught with difficulties, due to the fact that the unobservable space is not the null space. When using a Kalman filter estimator to perform the tracking, significant errors arise which could endanger the submarine. This work analyzes the performance of the Kalman filter when angle-only measurements are used to provide the target tracks. This paper addresses estimation unobservability and the minimal set of requirements that are needed to address it in this complex but real-world problem. Three major issues are addressed: the knowledge of navigation beacons/landmarks' locations, the minimal number of these beacons needed to maintain the course, and update rates of the angles of the landmarks as the periscope rotates and landmarks become obscured due to blockage and weather. The goal is to address the problem of navigation to and from the docks, while maintaining the traversing of the harbor channel based on maritime rules relying solely on the image-based data. The minimal number of beacons will be considered. For this effort, the image correlation from frame to frame is assumed to be achieved perfectly. Variation in the update rates and the dropping of data due to rotation and obscuration is considered

  9. A Novel Dynamic Physical Storage Model for Vehicle Navigation Maps

    Directory of Open Access Journals (Sweden)

    Shaohua Wang

    2016-04-01

    Full Text Available The physical storage model is one of the key technologies for vehicle navigation maps used in a navigation system. However, the performance of most traditional storage models is limited in dynamic navigation due to the static storage format they use. In this paper, we proposed a new physical storage model, China Navigation Data Format (CNDF, which helped access and update the navigation data. The CNDF model used the reach-based hierarchy method to build a road hierarchal network, which enhanced the efficiency of data compression. It also adopted the Linear Link Coding method, in which the start position was combined with the end position as the identification code for multi-level links, and each link traced up-level links consistently without recording the array of identifications. The navigation map of East China (including Beijing, Tianjin, Shandong, Hebei, and Jiangsu at 1:10,000, generated using the CNDF model, and the real time traffic information in Beijing were combined to test the performance of a navigation system using an embedded navigation device. Results showed that it cost less than 1 second each time to refresh the navigation map, and the accuracy of the hierarchal shortest-path algorithm was 99.9%. Our work implied that the CNDF model is efficient in vehicle navigation applications.

  10. INS/GPS Integrated Navigation Technology for Hypersonic UAV

    Directory of Open Access Journals (Sweden)

    Nana Meng

    2013-07-01

    Full Text Available INS/GPS integrated navigation system is studied in this paper for the hypersonic UAV in order to satisfy the precise guidance requirements of hypersonic UAV and in response to the defects while the inertial navigation system (INS and the global positioning system (GPS are being applied separately. The information of UAV including position, velocity and attitude can be obtained by using INS and GPS respectively after generating a reference trajectory. The corresponding errors of two navigation systems can be obtained through comparing the navigation information of the above two guidance systems. Kalman filter is designed to estimate the navigation errors and then the navigation information of INS are corrected. The non-equivalence relationship between the platform misalignment angle and attitude error angle are considered so that the navigation accuracy is further improved. The Simulink simulation results show that INS/GPS integrated navigation system can help to achieve higher accuracy and better anti-interference ability than INS navigation system and this system can also satisfy the navigation accuracy requirements of hypersonic UAV.  

  11. Multi-Flight-Phase GPS Navigation Filter Applications to Terrestrial Vehicle Navigation and Positioning

    Science.gov (United States)

    Park, Young W.; Montez, Moises N.

    1994-01-01

    A candidate onboard space navigation filter demonstrated excellent performance (less than 8 meter level RMS semi-major axis accuracy) in performing orbit determination of a low-Earth orbit Explorer satellite using single-frequency real GPS data. This performance is significantly better than predicted by other simulation studies using dual-frequency GPS data. The study results revealed the significance of two new modeling approaches evaluated in the work. One approach introduces a single-frequency ionospheric correction through pseudo-range and phase range averaging implementation. The other approach demonstrates a precise axis-dependent characterization of dynamic sample space uncertainty to compute a more accurate Kalman filter gain. Additionally, this navigation filter demonstrates a flexibility to accommodate both perturbational dynamic and observational biases required for multi-flight phase and inhomogeneous application environments. This paper reviews the potential application of these methods and the filter structure to terrestrial vehicle and positioning applications. Both the single-frequency ionospheric correction method and the axis-dependent state noise modeling approach offer valuable contributions in cost and accuracy improvements for terrestrial GPS receivers. With a modular design approach to either 'plug-in' or 'unplug' various force models, this multi-flight phase navigation filter design structure also provides a versatile GPS navigation software engine for both atmospheric and exo-atmospheric navigation or positioning use, thereby streamlining the flight phase or application-dependent software requirements. Thus, a standardized GPS navigation software engine that can reduce the development and maintenance cost of commercial GPS receivers is now possible.

  12. Collective navigation of complex networks: Participatory greedy routing

    CERN Document Server

    Kleineberg, Kaj-Kolja

    2016-01-01

    Many networks are used to transfer information or goods, in other words, they are navigated. The larger the network, the more difficult it is to navigate efficiently. Indeed, information routing in the Internet faces serious scalability problems due to its rapid growth, recently accelerated by the rise of the Internet of Things. Large networks like the Internet can be navigated efficiently if nodes, or agents, actively forward information based on hidden maps underlying these systems. However, in reality most agents will deny to forward messages, which has a cost, and navigation is impossible. Can we design appropriate incentives that lead to participation and global navigability? Here, we present an evolutionary game where agents share the value generated by successful delivery of information or goods. We show that global navigability can emerge, but its complete breakdown is possible as well. Furthermore, we show that the system tends to self-organize into local clusters of agents who participate in the nav...

  13. Fuzzy Logic Based Control for Autonomous Mobile Robot Navigation

    Science.gov (United States)

    Masmoudi, Mohamed Slim; Masmoudi, Mohamed

    2016-01-01

    This paper describes the design and the implementation of a trajectory tracking controller using fuzzy logic for mobile robot to navigate in indoor environments. Most of the previous works used two independent controllers for navigation and avoiding obstacles. The main contribution of the paper can be summarized in the fact that we use only one fuzzy controller for navigation and obstacle avoidance. The used mobile robot is equipped with DC motor, nine infrared range (IR) sensors to measure the distance to obstacles, and two optical encoders to provide the actual position and speeds. To evaluate the performances of the intelligent navigation algorithms, different trajectories are used and simulated using MATLAB software and SIMIAM navigation platform. Simulation results show the performances of the intelligent navigation algorithms in terms of simulation times and travelled path. PMID:27688748

  14. Computer-assisted navigation in knee arthroplasty: a critical appraisal.

    Science.gov (United States)

    Venkatesan, Muralidharan; Mahadevan, Devendra; Ashford, Robert U

    2013-10-01

    The purpose of this review was to appraise the use of computer-assisted navigation in total knee arthroplasty and to assess whether this technology has improved clinical outcomes. Studies were identified through searches in MEDLINE, Embase, and PubMed. Numerous studies have shown improved leg and component alignment using navigation systems. However, the better alignment achieved in navigated knee arthroplasty has not been shown to lead to better clinical outcomes. Navigated knee arthroplasty had lower calculated blood loss and lower incidence of fat embolism compared with conventional knee arthroplasty using intramedullary jigs. It may be most valued when dealing with complex knee deformities, revision surgery, or minimally invasive surgery. Navigated knee arthroplasty, however, is only cost-effective in centers with a high volume of joint replacements. Overall, computer-assisted navigated knee arthroplasty provides some advantages over conventional surgery, but its clinical benefits to date are unclear and remain to be defined on a larger scale.

  15. Fuzzy Logic Based Control for Autonomous Mobile Robot Navigation.

    Science.gov (United States)

    Omrane, Hajer; Masmoudi, Mohamed Slim; Masmoudi, Mohamed

    This paper describes the design and the implementation of a trajectory tracking controller using fuzzy logic for mobile robot to navigate in indoor environments. Most of the previous works used two independent controllers for navigation and avoiding obstacles. The main contribution of the paper can be summarized in the fact that we use only one fuzzy controller for navigation and obstacle avoidance. The used mobile robot is equipped with DC motor, nine infrared range (IR) sensors to measure the distance to obstacles, and two optical encoders to provide the actual position and speeds. To evaluate the performances of the intelligent navigation algorithms, different trajectories are used and simulated using MATLAB software and SIMIAM navigation platform. Simulation results show the performances of the intelligent navigation algorithms in terms of simulation times and travelled path.

  16. Intelligent personal navigator supported by knowledge-based systems for estimating dead reckoning navigation parameters

    Science.gov (United States)

    Moafipoor, Shahram

    Personal navigators (PN) have been studied for about a decade in different fields and applications, such as safety and rescue operations, security and emergency services, and police and military applications. The common goal of all these applications is to provide precise and reliable position, velocity, and heading information of each individual in various environments. In the PN system developed in this dissertation, the underlying assumption is that the system does not require pre-existing infrastructure to enable pedestrian navigation. To facilitate this capability, a multisensor system concept, based on the Global Positioning System (GPS), inertial navigation, barometer, magnetometer, and a human pedometry model has been developed. An important aspect of this design is to use the human body as navigation sensor to facilitate Dead Reckoning (DR) navigation in GPS-challenged environments. The system is designed predominantly for outdoor environments, where occasional loss of GPS lock may happen; however, testing and performance demonstration have been extended to indoor environments. DR navigation is based on a relative-measurement approach, with the key idea of integrating the incremental motion information in the form of step direction (SD) and step length (SL) over time. The foundation of the intelligent navigation system concept proposed here rests in exploiting the human locomotion pattern, as well as change of locomotion in varying environments. In this context, the term intelligent navigation represents the transition from the conventional point-to-point DR to dynamic navigation using the knowledge about the mechanism of the moving person. This approach increasingly relies on integrating knowledge-based systems (KBS) and artificial intelligence (AI) methodologies, including artificial neural networks (ANN) and fuzzy logic (FL). In addition, a general framework of the quality control for the real-time validation of the DR processing is proposed, based on a

  17. Software framework for off-road autonomous robot navigation system

    Institute of Scientific and Technical Information of China (English)

    WU Er-yong; ZHOU Wen-hui; ZHANG Li; DAI Guo-jun

    2009-01-01

    This paper presents a software framework for off-road autonomous robot navigation system. With the requirements of accurate terrain perception and instantaneous obstacles detection, one navigation software framework was advanced based on the principles of "three layer architecture" of intelligence system. Utilized the technologies of distributed system, machine learning and multiple sensor fusion, individual functional module was discussed. This paper aims to provide a framework reference for autonomous robot navigation system design.

  18. Adaptive Human aware Navigation based on Motion Pattern Analysis

    DEFF Research Database (Denmark)

    Tranberg, Søren; Svenstrup, Mikael; Andersen, Hans Jørgen

    2009-01-01

    Respecting people’s social spaces is an important prerequisite for acceptable and natural robot navigation in human environments. In this paper, we describe an adaptive system for mobile robot navigation based on estimates of whether a person seeks to interact with the robot or not. The estimates...... in a real world setting. The results demonstrate that the system is able to learn to navigate based on past interaction experiences, and to adapt to different behaviors over time....

  19. The sex specificity of navigational strategies in Alzheimer disease.

    Science.gov (United States)

    Cushman, Laura A; Duffy, Charles J

    2007-01-01

    Alzheimer disease (AD) is associated with navigational impairments that limit functional independence. We have now examined the role of cognitive and perceptual mechanisms in the navigational impairment of AD to test the hypothesis that men and women with AD may focus on different navigational cues. We conducted navigational, neuropsychologic, and psychophysical testing in men and women from 3 groups: older normal controls, patients with mild cognitive impairment, and patients with AD. Men and women showed parallel declines in navigational capacities from the older normal control, to the mild cognitive impairment, to the AD groups with men and women making similar numbers of errors but different types of errors. There were small sex differences in neuropsychologic and psychophysical performance but large sex differences in how those measures related to navigational capacity: men showed strong links between visual motion processing and navigation. Women showed strong links between verbal capacities and navigation. The findings of these cross-sectional comparisons suggest that there may be sex differences in the progressive navigational decline of AD: men and women who are impaired to the same degree may suffer somewhat different patterns of decline with men relying more on visuospatial processing and women relying more on verbal mediation.

  20. GPS-Aided Gyroscope-Free Inertial Navigation Systems

    OpenAIRE

    Park, Sungsu; Tan, Chin-Woo

    2002-01-01

    A gyroscope-free inertial navigation system uses only accelerometers to compute navigation trajectories. It is a low-cost navigation system, but its output error diverges at a rate that is an order faster than that of a conventional gyroscope-based system. So integration with an external reference system, such as the Global Positioning System, is necessary for long-term navigation applications. In this pa-per, an integrated GPS and gyroscope-free INS system is designed to achieve stable long-...

  1. Fault-tolerant and Diagnostic Methods for Navigation

    DEFF Research Database (Denmark)

    Blanke, Mogens

    2003-01-01

    Precise and reliable navigation is crucial, and for reasons of safety, essential navigation instruments are often duplicated. Hardware redundancy is mostly used to manually switch between instruments should faults occur. In contrast, diagnostic methods are available that can use analytic redundancy...... to diagnose faults and autonomously provide valid navigation data, disregarding any faulty sensor data and use sensor fusion to obtain a best estimate for users. This paper discusses how diagnostic and fault-tolerant methods are applicable in marine systems. An example chosen is sensor fusion for navigation...

  2. A Novel Navigation Algorithm for Hexagonal Hexapod Robot

    Directory of Open Access Journals (Sweden)

    Mohiuddin Ahmed

    2010-01-01

    Full Text Available Problem statement: Wheeled robots are not very well suited for navigation over uneven terrains. Hexapod robots have some advantages over wheeled robots when negotiating and navigating on rugged terrain. Approach: Different gaits of hexapods can be developed for different kinds of locomotion and obstacle avoidance. Results: In this research a novel algorithm has been developed for hexapod robots navigation. Conclusion: Implementation of the developed algorithm on a hexapod prototype showed desirable performance in terms of stable navigation with simultaneous gait transition over different terrains.

  3. X-Ray Pulsar Based Navigation and Time Determination Project

    Data.gov (United States)

    National Aeronautics and Space Administration — DARPA recently initiated the XNAV program to undertake development of GPS independent, precision navigation and time determination based on observations of certain...

  4. Navigation Support for Learners in Informal Learning Networks

    NARCIS (Netherlands)

    Drachsler, Hendrik

    2009-01-01

    Drachsler, H. (2009). Navigation Support for Learners in Informal Learning Networks. Unpublished doctoral thesis. Oktober, 16, 2009, Heerlen, The Netherlands: Open University of the Netherlands/CELSTEC.

  5. Navigation Method for Autonomous Robots in a Dynamic Indoor Environment

    Directory of Open Access Journals (Sweden)

    Stanislav Věchet

    2013-11-01

    Full Text Available The present paper considers issues related to navigation by autonomous mobile robots in overcrowded dynamic indoor environments (e.g., shopping malls, exhibition halls or convention centers. For robots moving among potentially unaware bystanders, safety is a key issue. A navigation method based on mixed potential field path planning is proposed, in cooperation with active artificial landmarks-based localization, in particular the bearing of infrared beacons placed in known coordinates processed via particle filters. Simulation experiments and tests in unmodified real-world environments with the actual robot show the proposed navigation system allows the robot to successfully navigate safely among bystanders.

  6. Training in Patient Navigation: A Review of the Research Literature.

    Science.gov (United States)

    Ustjanauskas, Amy E; Bredice, Marissa; Nuhaily, Sumayah; Kath, Lisa; Wells, Kristen J

    2016-05-01

    Despite the proliferation of patient navigation programs designed to increase timely receipt of health care, little is known about the content and delivery of patient navigation training, or best practices in this arena. The current study begins to address these gaps in understanding, as it is the first study to comprehensively review descriptions of patient navigation training in the peer-reviewed research literature. Seventy-five patient navigation efficacy studies published since 1995, identified through PubMed and by the authors, were included in this narrative review. Fifty-nine of the included studies (79%) mentioned patient navigation training, and 55 of these studies additionally provided a description of training. Most studies did not thoroughly document patient navigation training practices. Additionally, several topics integral to the role of patient navigators, as well as components of training central to successful adult learning, were not commonly described in the research literature. Descriptions of training also varied widely across studies in terms of duration, location, format, learning strategies employed, occupation of trainer, and content. These findings demonstrate the need for established standards of navigator training as well as for future research on the optimal delivery and content of patient navigation training.

  7. Image matching navigation based on fuzzy information

    Institute of Scientific and Technical Information of China (English)

    田玉龙; 吴伟仁; 田金文; 柳健

    2003-01-01

    In conventional image matching methods, the image matching process is mostly based on image statistic information. One aspect neglected by all these methods is that there is much fuzzy information contained in these images. A new fuzzy matching algorithm based on fuzzy similarity for navigation is presented in this paper. Because the fuzzy theory is of the ability of making good description of the fuzzy information contained in images, the image matching method based on fuzzy similarity would look forward to producing good performance results. Experimental results using matching algorithm based on fuzzy information also demonstrate its reliability and practicability.

  8. Dual RF Astrodynamic GPS Orbital Navigator Satellite

    Science.gov (United States)

    Kanipe, David B.; Provence, Robert Steve; Straube, Timothy M.; Reed, Helen; Bishop, Robert; Lightsey, Glenn

    2009-01-01

    Dual RF Astrodynamic GPS Orbital Navigator Satellite (DRAGONSat) will demonstrate autonomous rendezvous and docking (ARD) in low Earth orbit (LEO) and gather flight data with a global positioning system (GPS) receiver strictly designed for space applications. ARD is the capability of two independent spacecraft to rendezvous in orbit and dock without crew intervention. DRAGONSat consists of two picosatellites (one built by the University of Texas and one built by Texas A and M University) and the Space Shuttle Payload Launcher (SSPL); this project will ultimately demonstrate ARD in LEO.

  9. Local Navigation for Unmanned Group Vehicles

    Science.gov (United States)

    2005-12-01

    processing power may allow the development of one all- encompassing navigation algorithm, but more likely, autonomous systems will switch between algorithms... planifier précisément les séquences des mouvements du robot. La portée des résultats : L’évitement des obstacles à deux dimensions est plus ou moins un...and interacts with the terrain. This process is much more difficult for robotic vehicles. In addition to the limitations of sensing equipment, it has

  10. A relativistic and autonomous navigation satellite system

    CERN Document Server

    Delva, Pacôme; Kostić, Uros; Carloni, Sante

    2011-01-01

    A relativistic positioning system has been proposed by Bartolom\\'e Coll in 2002. Since then, several group developed this topic with different approaches. I will present a work done in collaboration with Ljubljana University and the ESA Advanced Concepts Team. We developed a concept, Autonomous Basis of Coordinates, in order to take advantage of the full autonomy of a satellite constellation for navigation and positioning, by means of satellite inter-links. I will present the advantages of this new paradigm and a number of potential application for reference systems, geophysics and relativistic gravitation.

  11. Fiber optic gyroscopes for vehicle navigation systems

    Science.gov (United States)

    Kumagai, Tatsuya; Soekawa, Hirokazu; Yuhara, Toshiya; Kajioka, Hiroshi; Oho, Shigeru; Sonobe, Hisao

    1994-03-01

    Fiber optic gyroscopes (FOGs) have been developed for vehicle navigation systems and are used in Toyota Motor Corporation models Mark II, Chaser and Cresta in Japan. Use of FOGs in these systems requires high reliability under a wide range of conditions, especially in a temperature range between -40 and 85 degree(s)C. In addition, a high cost-performance ratio is needed. We have developed optical and electrical systems that are inexpensive and can perform well. They are ready to be mass-produced. FOGs have already been installed in luxury automobiles, and will soon be included in more basic vehicles. We have developed more inexpensive FOGs for this purpose.

  12. Optimum Route Selection for Vehicle Navigation

    Directory of Open Access Journals (Sweden)

    Dalip

    2016-02-01

    Full Text Available The objective of Optimum Route Selection for Vehicle Navigation System (ORSVNS article is to develop a system, which provides information about real time alternate routes to the drivers and also helps in selecting the optimal route among all the alternate routes from an origin to destination. Two types of query systems, special and general, are designed for drivers. Here, the criterion for route selection is introduced using primary and secondary road attributes. The presented methodology helps the drivers in better decision making to choose optimal route using fuzzy logic. For experimental results ORSVNS is tested over 220 km portion of Haryana state in India.

  13. SCANNING VISION SYSTEM FOR VEHICLE NAVIGATION

    Directory of Open Access Journals (Sweden)

    O. Sergiyenko

    2012-01-01

    Full Text Available The new model of the scanning vision system for vehicles is offered. The questions of creation, functioning and interaction of the system units and elements are considered. The mathematical apparatus for processing digital information inside the system and for determining distances and an-gle standard in the offered system is worked out. Expected accuracy, functioning speed, range of ac-tion, energy consumption when using the system are determined. The possible areas of the developed automatic navigation system use are offered.

  14. Road boundary detection for autonomous vehicle navigation

    Energy Technology Data Exchange (ETDEWEB)

    Davis, L.S.; Kushner, T.R.; LeMoigne, J.J.; Waxman, A.M.

    1986-03-01

    The Computer Vision Laboratory at the University Maryland for the past year has been developing a computer vision system for autonomous ground navigation of roads and road networks for the Defense Advanced Research Projects Agency's Strategic Computing Program. The complete system runs on a VAX 11/785, but certain parts of it have been reimplemented on a VICOM image processing sysem for experimentation on an autonomous vehicle built for the Martin Marietta Corp., Aerospace Division, in Denver, Colorado. A brief overview is given of the principal software components of the system and the VICOM implementation in detail.

  15. Route selection for vehicle navigation and control

    OpenAIRE

    G. Pang; Chu, MH

    2007-01-01

    This paper presents an application of neural-fuzzy methodology for the problem of route selection in a typical vehicle navigation and control system. The idea of the primary attributes of a route is discussed, and a neural-fuzzy system is developed to help a user to select a route out of the many possible routes from an origin to the destination. The user may not adopt the recommendation provided by the system and choose an alternate route. One novel feature of the system is that the neural-f...

  16. Semantic Visualization and Navigation in Textual Corpus

    CERN Document Server

    Kboubi, Férihane; BenAhmed, Mohamed

    2012-01-01

    This paper gives a survey of related work on the information visualization domain and study the real integration of the cartography paradigms in actual information search systems. Based on this study, we propose a semantic visualization and navigation approach which offer to users three search modes: precise search, connotative search and thematic search. The objective is to propose to the users of an information search system, new interaction paradigms which support the semantic aspect of the considered information space and guide users in their searches by assisting them to locate their interest center and to improve serendipity.

  17. Fault tolerant highly reliable inertial navigation system

    Science.gov (United States)

    Jeerage, Mahesh; Boettcher, Kevin

    This paper describes a development of failure detection and isolation (FDI) strategies for highly reliable inertial navigation systems. FDI strategies are developed based on the generalized likelihood ratio test (GLRT). A relationship between detection threshold and false alarm rate is developed in terms of the sensor parameters. A new method for correct isolation of failed sensors is presented. Evaluation of FDI performance parameters, such as false alarm rate, wrong isolation probability, and correct isolation probability, are presented. Finally a fault recovery scheme capable of correcting false isolation of good sensors is presented.

  18. Navigating in Higher Education (NiHE)

    DEFF Research Database (Denmark)

    Thingholm, Hanne Balsby

    and students experience during their teaching and studying. The purpose of the survey is to explore differences and similarities in how teachers and students navigate in higher education. The study will provide data for qualifying teaching by developing a Meta- cognitive Oriented Learning Environment (MOLE......). MOLE is characterized by teaching High Order Thinking and thereby achieving Deep Understanding (HOT-DUG). Qualifying education in this way results in deeper understanding for the students regarding not only what to study but also why and how to study, the teachers become more explicit about objectives...

  19. Capsules with external navigation and triggered release.

    Science.gov (United States)

    Shchukin, Dmitry G; Shchukina, Elena

    2014-10-01

    Encapsulation is an important technology for pharmaceutical industry, food production, et cetera. Its current level of development requires capsule functionalization. One of the interesting ideas to provide new functionality to the microcapsule and nanocapsule is layer-by-layer deposition of functional species. This technique provides step-by-step adsorption of various species (polyelectrolytes, nanoparticles, proteins) when the layer growth is controlled by electrostatic, hydrogen bonding, hydrophobic forces and forming multilayer shells with nanometer precision. This review article introduces recent achievements of layer-by-layer technique attaining external navigation ability and release properties the capsule shell.

  20. 75 FR 32275 - Regulated Navigation Area; Gulf Intracoastal Waterway, Inner Harbor Navigation Canal, Harvey...

    Science.gov (United States)

    2010-06-08

    ..., Inner Harbor Navigation Canal, Harvey Canal, Algiers Canal, New Orleans, LA AGENCY: Coast Guard, DHS...), Harvey Canal, and Algiers Canal during severe hurricane conditions. Vessels will not be permitted to stay... communities within the IHNC, Harvey, and Algiers Canals from potential hazards associated with vessels...

  1. Short-range navigation: does it contribute to understanding navigation over longer distances?

    Science.gov (United States)

    Collett

    1996-01-01

    A major reason for analysing short-range navigation is that it is relatively easy to record on video tape the details of an animal's behaviour over an area of about a square metre. Frequently, the orientation of the animal's body is revealed in addition to its trajectory through space. This is particularly useful in the study of insect navigation, the subject of the four contributions to this section. An insect's eyes are fixed in its head, and there are often no significant head movements during flight. Consequently, reasonable assumptions can be made about where the insect looks while it navigates and how the image of its surroundings moves over its retina. All four contributions depend to a large degree upon being able to freeze behaviour on video tape and to infer what the animal sees. To what extent do the conclusions using the abundant information that can be collected in this way extrapolate to navigation on a larger scale? Clearly, the coded information that instructs the monarch butterfly on its migrations from wide areas of North America to northern Michoacan in Mexico contains elements unique to long-distance travel. But there may be many similarities in the mechanisms available to an orchid bee as it travels over its 20 km foraging route from orchid to orchid and a wasp negotiating the last few metres through a complex environment to reach its nest.

  2. Optical flow and inertial navigation system fusion in the UAV navigation

    Science.gov (United States)

    Popov, A.; Miller, A.; Miller, B.; Stepanyan, K.

    2016-10-01

    In recent years navigation on the basis of computation of the camera path and the distance to obstacles with the aid of field of image motion velocities (i.e. optical flow, OF) became highly demanded particularly in the area of relatively small and even micro unmanned aerial vehicles (UAV). Video sequences captured by onboard camera gives the possibility of the OF calculation with the aid of relatively simple algorithms like Lucas-Kanade. The complete OF is the linear function of linear and angular velocities of the UAV which provides an additional means for the navigation parameters estimation. Such UAV navigation approach presumes that on-board camera gives the video sequence of the underlying surface images providing the information about the UAV evolutions. Navigation parameters are extracted on the basis of exact OF formulas which gives the observation process description for estimation based on Kalman filtering. One can expect the high accuracy of the estimated parameters (linear and angular velocities) because their number is substantially less than the number of measurements (practically the number of the camera pixels).

  3. Navigational Support in Lifelong Learning: Enhancing Effectiveness through Indirect Social Navigation

    Science.gov (United States)

    Janssen, Jose; van den Berg, Bert; Tattersall, Colin; Hummel, Hans; Koper, Rob

    2007-01-01

    Efficient and effective lifelong learning requires that learners can make well informed choices from a vast amount of learning opportunities. This article proposes to support learners by drawing on principles of self-organization and indirect social navigation; by analysing choices made by learners who went before and feeding this information back…

  4. 33 CFR 150.715 - What are the requirements for lights used as aids to navigation?

    Science.gov (United States)

    2010-07-01

    ... lights used as aids to navigation? 150.715 Section 150.715 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) DEEPWATER PORTS DEEPWATER PORTS: OPERATIONS Aids to Navigation § 150.715 What are the requirements for lights used as aids to navigation? (a) Each light under part...

  5. 33 CFR 150.710 - What are the requirements for supplying power to aids to navigation?

    Science.gov (United States)

    2010-07-01

    ... supplying power to aids to navigation? 150.710 Section 150.710 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) DEEPWATER PORTS DEEPWATER PORTS: OPERATIONS Aids to Navigation § 150.710 What are the requirements for supplying power to aids to navigation? The power of...

  6. Social Navigation in Web Lectures: A Study of VirtPresenter

    Science.gov (United States)

    Mertens, Robert; Ketterl, Markus; Brusilovsky, Peter

    2010-01-01

    Purpose: Social navigation is an emerging trend for navigation in hypermedia. With social navigation, users can be guided through large volumes of learning content by cues which integrate the browsing history of past users. Earlier papers have shown that social navigation is suitable for navigation not only in classic hypermedia but also in…

  7. 33 CFR 150.705 - What are the requirements for maintaining and inspecting aids to navigation?

    Science.gov (United States)

    2010-07-01

    ... maintaining and inspecting aids to navigation? 150.705 Section 150.705 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) DEEPWATER PORTS DEEPWATER PORTS: OPERATIONS Aids to Navigation § 150.705 What are the requirements for maintaining and inspecting aids to navigation? (a)...

  8. Low-Cost Navigation Sensors and Integration Technology (Capteurs de navigation a faible cout et technologie d’integration)

    Science.gov (United States)

    2010-03-01

    auditeurs soient informés sur les pratiques actuelles mais aussi sur les capteurs et leurs applications . Des orientations technologiques ont été...Mar 2010 Low-Cost Navigation Sensors and Integration Technology ( Capteurs de navigation à faible coût et technologie d’intégration) Research and...to-date with current practices, as well as, information on sensors, algorithms, and applications . Applications were described for navigating in

  9. Urban, Indoor and Subterranean Navigation Sensors and Systems (Capteurs et systemes de navigation urbains, interieurs et souterrains)

    Science.gov (United States)

    2010-11-01

    SET-114 Urban, Indoor and Subterranean Navigation Sensors and Systems ( Capteurs et systèmes de navigation urbains, intérieurs et souterrains...SET-114 Urban, Indoor and Subterranean Navigation Sensors and Systems ( Capteurs et systèmes de navigation urbains, intérieurs et souterrains...1 2.1.3 Session 4: Simulation and Testing 2-2 2.1.4 Session 5: Military Systems and Applications 2-2 2.1.5 Session 6: Robust GNSS Integration

  10. Structure and navigation for electronic publishing

    Science.gov (United States)

    Tillinghast, John; Beretta, Giordano B.

    1998-01-01

    The sudden explosion of the World Wide Web as a new publication medium has given a dramatic boost to the electronic publishing industry, which previously was a limited market centered around CD-ROMs and on-line databases. While the phenomenon has parallels to the advent of the tabloid press in the middle of last century, the electronic nature of the medium brings with it the typical characteristic of 4th wave media, namely the acceleration in its propagation speed and the volume of information. Consequently, e-publications are even flatter than print media; Shakespeare's Romeo and Juliet share the same computer screen with a home-made plagiarized copy of Deep Throat. The most touted tool for locating useful information on the World Wide Web is the search engine. However, due to the medium's flatness, sought information is drowned in a sea of useless information. A better solution is to build tools that allow authors to structure information so that it can easily be navigated. We experimented with the use of ontologies as a tool to formulate structures for information about a specific topic, so that related concepts are placed in adjacent locations and can easily be navigated using simple and ergonomic user models. We describe our effort in building a World Wide Web based photo album that is shared among a small network of people.

  11. Navigation system for neurosurgery with PC platform.

    Science.gov (United States)

    Akatsuka, Y; Shibasaki, T; Saito, A; Kosaka, A; Matsuzaki, H; Asano, T; Furuhashi, Y

    2000-01-01

    This paper presents a navigation system for a surgical microscope and an endoscope which can be used for neurosurgery. In this system, a wireframe model of a target tumor and other significant anatomical landmarks are superimposed in real-time onto live video images taken from the microscope and the endoscope. The wireframe model is generated from a CT/MRI slice images. Overlaid images are simultaneously displayed in the same monitor using the picture-in-picture function so that the surgeon can concentrate on the single monitor during the surgery. The system measures the position and orientation of the patient using specially designed non-contact sensing devices mounted on the microscope and the endoscope. Based on this real-time measurement, the system displays other useful information about the navigation as well as the rendered wireframe. The accuracy of registration between the wireframe model and the actual live view is less than 2 mm. We tested this system in actual surgery several times, and verified its performance and effectiveness.

  12. Olfaction, navigation, and the origin of isocortex

    Science.gov (United States)

    Aboitiz, Francisco; Montiel, Juan F.

    2015-01-01

    There are remarkable similarities between the brains of mammals and birds in terms of microcircuit architecture, despite obvious differences in gross morphology and development. While in reptiles and birds the most expanding component (the dorsal ventricular ridge) displays an overall nuclear shape and derives from the lateral and ventral pallium, in mammals a dorsal pallial, six-layered isocortex shows the most remarkable elaboration. Regardless of discussions about possible homologies between mammalian and avian brains, a main question remains in explaining the emergence of the mammalian isocortex, because it represents a unique phenotype across amniotes. In this article, we propose that the origin of the isocortex was driven by behavioral adaptations involving olfactory driven goal-directed and navigating behaviors. These adaptations were linked with increasing sensory development, which provided selective pressure for the expansion of the dorsal pallium. The latter appeared as an interface in olfactory-hippocampal networks, contributing somatosensory information for navigating behavior. Sensory input from other modalities like vision and audition were subsequently recruited into this expanding region, contributing to multimodal associative networks. PMID:26578863

  13. Olfaction, navigation, and the origin of isocortex.

    Science.gov (United States)

    Aboitiz, Francisco; Montiel, Juan F

    2015-01-01

    There are remarkable similarities between the brains of mammals and birds in terms of microcircuit architecture, despite obvious differences in gross morphology and development. While in reptiles and birds the most expanding component (the dorsal ventricular ridge) displays an overall nuclear shape and derives from the lateral and ventral pallium, in mammals a dorsal pallial, six-layered isocortex shows the most remarkable elaboration. Regardless of discussions about possible homologies between mammalian and avian brains, a main question remains in explaining the emergence of the mammalian isocortex, because it represents a unique phenotype across amniotes. In this article, we propose that the origin of the isocortex was driven by behavioral adaptations involving olfactory driven goal-directed and navigating behaviors. These adaptations were linked with increasing sensory development, which provided selective pressure for the expansion of the dorsal pallium. The latter appeared as an interface in olfactory-hippocampal networks, contributing somatosensory information for navigating behavior. Sensory input from other modalities like vision and audition were subsequently recruited into this expanding region, contributing to multimodal associative networks.

  14. Navigating actions through the rodent parietal cortex

    Directory of Open Access Journals (Sweden)

    Jonathan R. Whitlock

    2014-05-01

    Full Text Available The posterior parietal cortex (PPC participates in a manifold of cognitive functions, including visual attention, working memory, spatial processing and movement planning. Given the vast interconnectivity of PPC with sensory and motor areas, it is not surprising that neuronal recordings show that PPC often encodes mixtures of spatial information as well as the movements required to reach a goal. Recent work sought to discern the relative strength of spatial versus motor signaling in PPC by recording single unit activity in PPC of freely behaving rats during selective changes in either the spatial layout of the local environment or in the pattern of locomotor behaviors executed during navigational tasks. The results revealed unequivocally a predominant sensitivity of PPC neurons to locomotor action structure, with subsets of cells even encoding upcoming movements more than 1 second in advance. In light of these and other recent findings in the field, I propose that one of the key contributions of PPC to navigation is the synthesis of goal-directed behavioral sequences, and that the rodent PPC may serve as an apt system to investigate cellular mechanisms for spatial motor planning as traditionally studied in humans and monkeys.

  15. Development of cue integration in human navigation.

    Science.gov (United States)

    Nardini, Marko; Jones, Peter; Bedford, Rachael; Braddick, Oliver

    2008-05-06

    Mammalian navigation depends both on visual landmarks and on self-generated (e.g., vestibular and proprioceptive) cues that signal the organism's own movement [1-5]. When these conflict, landmarks can either reset estimates of self-motion or be integrated with them [6-9]. We asked how humans combine these information sources and whether children, who use both from a young age [10-12], combine them as adults do. Participants attempted to return an object to its original place in an arena when given either visual landmarks only, nonvisual self-motion information only, or both. Adults, but not 4- to 5-year-olds or 7- to 8-year-olds, reduced their response variance when both information sources were available. In an additional "conflict" condition that measured relative reliance on landmarks and self-motion, we predicted behavior under two models: integration (weighted averaging) of the cues and alternation between them. Adults' behavior was predicted by integration, in which the cues were weighted nearly optimally to reduce variance, whereas children's behavior was predicted by alternation. These results suggest that development of individual spatial-representational systems precedes development of the capacity to combine these within a common reference frame. Humans can integrate spatial cues nearly optimally to navigate, but this ability depends on an extended developmental process.

  16. Spacecraft formation flying: Dynamics, control and navigation

    Science.gov (United States)

    Alfriend, Kyle Terry; Vadali, Srinivas Rao; Gurfil, Pini; How, Jonathan; Breger, Louis S.

    2009-12-01

    Space agencies are now realizing that much of what has previously been achieved using hugely complex and costly single platform projects - large unmanned and manned satellites (including the present International Space Station) - can be replaced by a number of smaller satellites networked together. The key challenge of this approach, namely ensuring the proper formation flying of multiple craft, is the topic of this second volume in Elsevier's Astrodynamics Series, Spacecraft Formation Flying: Dynamics, control and navigation. In this unique text, authors Alfriend et al. provide a coherent discussion of spacecraft relative motion, both in the unperturbed and perturbed settings, explain the main control approaches for regulating relative satellite dynamics, using both impulsive and continuous maneuvers, and present the main constituents required for relative navigation. The early chapters provide a foundation upon which later discussions are built, making this a complete, standalone offering. Intended for graduate students, professors and academic researchers in the fields of aerospace and mechanical engineering, mathematics, astronomy and astrophysics, Spacecraft Formation Flying is a technical yet accessible, forward-thinking guide to this critical area of astrodynamics.

  17. The European Satellite Navigation System Galileo

    Institute of Scientific and Technical Information of China (English)

    G.W. Hein; T. Pany

    2003-01-01

    This paper starts with a brief discussion of the Galileo project status and with a description of the present Galileo architecture (space segment, ground segment, user segment). It focuses on explaining special features compared to the American GPS system. The presentation of the user segment comprises a discussion of the actual Galileo signal structure. The Galileo carrier frequency, modulation scheme and data rate of all 10 navigation signals are described as well as parameters of the search and rescue service. The navigation signals are used to realize three types of open services, the safety of life service, two types of commercial services and the public regulated service. The signal performance in terms of the pseudorange code error due to thermal noise and multipath is discussed as well as interference to and from other radionavigation services broadcasting in the E5 and E6 frequency band. The interoperability and compatibility of Galileo and GPS is realized by a properly chosen signal structures in E5a/L5 and E2-L1-E1 and compatible geodetic and time reference frames. Some new results on reciprocal GPS/Galileo signal degradation due to signal overlay are presented as well as basic requirements on the Galileo code sequences.

  18. Navigational Challenges for a Europa Flyby Mission

    Science.gov (United States)

    Martin-Mur, Tomas J.; Ionasescu, Rodica; Valerino, Powtawche; Criddle, Kevin; Roncoli, Ralph

    2014-01-01

    Jupiter's moon Europa is a prime candidate in the search for present-day habitable environments outside of the Earth. A number of missions have provided increasingly detailed images of the complex surface of Europa, including the Galileo mission, which also carried instruments that allowed for a limited investigation of the environment of Europa. A new mission to Europa is needed to pursue these exciting discoveries using close-up observations with modern instrumentation designed to address the habitability of Europa. In all likelihood the most cost effective way of doing this would be with a spacecraft carrying a comprehensive suite of instruments and performing multiple flybys of Europa. A number of notional trajectory designs have been investigated, utilizing gravity assists from other Galilean moons to decrease the period of the orbit and shape it in order to provide a globally distributed coverage of different regions of Europa. Navigation analyses are being performed on these candidate trajectories to assess the total Delta V that would be needed to complete the mission, to study how accurately the flybys could be executed, and to determine which assumptions most significantly affect the performance of the navigation system.

  19. Design of a Reconfigurable Platform for Navigation Signal Simulation

    Directory of Open Access Journals (Sweden)

    Ming Dexiang

    2013-05-01

    Full Text Available Navigation signal simulator can generate signals consistent with real GNSS (Global Navigation Satellite System signals, which can be processed by GNSS receivers in the same manner as it processes satellite signals in a real testing environment. The simulator can offer a high-fidelity means of testing GNSS receivers and other related systems. Such tests can be carried out in laboratories due to control of the GNSS constellation and global atmospheric environment by a single device. The navigation signal simulator, which can provide a real-like environment for the research and testing of navigation receivers, has been the key instrument for developing navigation systems and receiving devices, particularly for high-dynamic receivers. Therefore it has increasingly received widespread attentions in military and industrial sectors. With the development of a variety of new navigation systems and signal standards, there is a higher demand for the compatibility and renewal speed of the navigation signal simulators; specifically, it should be multi-mode and reconfigurable in order to realize the flexible design of navigation systems. Although a lot of GNSS simulators have been developed and used, the reconfigurable technologies have not yet appeared in the literature and applied to practices. This means that the existing simulators cannot achieve simulation of multiple GNSS signals by reconfiguration of the software and hardware on the same platform. In this paper, a new reconfigurable platform for navigation signal simulation is proposed and studied, aiming to simulate multi-mode and multi-frequency navigation signals. The performance of the proposed platform is validated from three perspectives: mathematic simulation software, output signals and receiver operation. The result shows that the platform can generate multi-mode and multi-frequency navigation signals through reconfiguration of the software and hardware on the same platform, hence supporting

  20. Bayesian statistics and information fusion for GPS-denied navigation

    Science.gov (United States)

    Copp, Brian Lee

    It is well known that satellite navigation systems are vulnerable to disruption due to jamming, spoofing, or obstruction of the signal. The desire for robust navigation of aircraft in GPS-denied environments has motivated the development of feature-aided navigation systems, in which measurements of environmental features are used to complement the dead reckoning solution produced by an inertial navigation system. Examples of environmental features which can be exploited for navigation include star positions, terrain elevation, terrestrial wireless signals, and features extracted from photographic data. Feature-aided navigation represents a particularly challenging estimation problem because the measurements are often strongly nonlinear, and the quality of the navigation solution is limited by the knowledge of nuisance parameters which may be difficult to model accurately. As a result, integration approaches based on the Kalman filter and its variants may fail to give adequate performance. This project develops a framework for the integration of feature-aided navigation techniques using Bayesian statistics. In this approach, the probability density function for aircraft horizontal position (latitude and longitude) is approximated by a two-dimensional point mass function defined on a rectangular grid. Nuisance parameters are estimated using a hypothesis based approach (Multiple Model Adaptive Estimation) which continuously maintains an accurate probability density even in the presence of strong nonlinearities. The effectiveness of the proposed approach is illustrated by the simulated use of terrain referenced navigation and wireless time-of-arrival positioning to estimate a reference aircraft trajectory. Monte Carlo simulations have shown that accurate position estimates can be obtained in terrain referenced navigation even with a strongly nonlinear altitude bias. The integration of terrain referenced and wireless time-of-arrival measurements is described along with

  1. A dialogue agent for navigation support in virtual reality

    NARCIS (Netherlands)

    Luin, van J.; Akker, op den H.J.A.; Nijholt, A.; Jacko, J.; Sears, A.

    2001-01-01

    We describe our work on designing a natural language accessible navigation agent for a virtual reality (VR) environment. The agent is part of an agent framework, which means that it can communicate with other agents. Its navigation task consists of guiding the visitors in the environment and to answ

  2. Information content in reflected global navigation satellite system signals

    DEFF Research Database (Denmark)

    Høeg, Per; Carlstrom, Anders

    2011-01-01

    The direct signals from satellites in global satellite navigation satellites systems (GNSS) as, GPS, GLONASS and GALILEO, constitute the primary source for positioning, navigation and timing from space. But also the reflected GNSS signals contain an important information content of signal travel...

  3. Mapping, Navigation, and Learning for Off-Road Traversal

    DEFF Research Database (Denmark)

    Konolige, Kurt; Agrawal, Motilal; Blas, Morten Rufus

    2009-01-01

    The challenge in the DARPA Learning Applied to Ground Robots (LAGR) project is to autonomously navigate a small robot using stereo vision as the main sensor. During this project, we demonstrated a complete autonomous system for off-road navigation in unstructured environments, using stereo vision...

  4. 14 CFR 121.121 - En route navigation facilities.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false En route navigation facilities. 121.121 Section 121.121 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Operations § 121.121 En route navigation facilities. (a) Except as provided in paragraph (b) of this...

  5. 14 CFR 121.103 - En route navigation facilities.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false En route navigation facilities. 121.103 Section 121.103 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... § 121.103 En route navigation facilities. (a) Except as provided in paragraph (b) of this section,...

  6. 14 CFR 125.51 - En route navigation facilities.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false En route navigation facilities. 125.51 Section 125.51 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... and Miscellaneous Requirements § 125.51 En route navigation facilities. (a) Except as provided...

  7. Evaluating the Performance of an Integrated Navigation System.

    NARCIS (Netherlands)

    Lorga, J.F.M.; Chu, Q.P.; Mulder, J.A.; Halsema, D. van

    2005-01-01

    In this paper, the authors propose to introduce and describe a newly developed precise tightly-coupled integrated navigation system. The performed experiments with the purpose of evaluating the system performance are shown. A complete description of the integrated navigation system hardware, includi

  8. Ultrasound-Aided Pedestrian Dead Reckoning for Indoor Navigation

    NARCIS (Netherlands)

    Fischer, C.; Muthukrishnan, K.; Hazas, M.; Gellersen, H.

    2008-01-01

    Ad hoc solutions for tracking and providing navigation support to emergency response teams is an important and safety-critical challenge. We propose a navigation system based on a combination of foot-mounted inertial sensors and ultrasound beacons. We evaluate experimentally the performance of our

  9. Admiral Zheng He——Legendary Chinese Navigator

    Institute of Scientific and Technical Information of China (English)

    R.Jinith de Silva

    2009-01-01

    <正>In the school curricula of the recent past, we were taught of seafaring nations such as the Spanish, the Portuguese, the Dutch, the English and the French and of the feats of their navigators such as Columbus, Vascode Gama, Bartholomes Dias, Magellan, etc., but never of a Chinese navigator called Zheng He, who crisscrossed the

  10. Comparative advantage between traditional and smart navigation systems

    Science.gov (United States)

    Shin, Jeongkyu; Kim, Pan-Jun; Kim, Seunghwan

    2013-03-01

    The smart navigation system that refers to real-time traffic data is believed to be superior to traditional navigation systems. To verify this belief, we created an agent-based traffic model and examined the effect of changing market share of the traditional shortest-travel-time algorithm based navigation and the smart navigation system. We tested our model on the grid and actual metropolitan road network structures. The result reveals that the traditional navigation system have better performance than the smart one as the market share of the smart navigation system exceeds a critical value, which is contrary to conventional expectation. We suggest that the superiority inversion between agent groups is strongly related to the traffic weight function form, and is general. We also found that the relationship of market share, traffic flow density and travel time is determined by the combination of congestion avoidance behavior of the smartly navigated agents and the inefficiency of shortest-travel-time based navigated agents. Our results can be interpreted with the minority game and extended to the diverse topics of opinion dynamics. This work was supported by the Original Technology Research Program for Brain Science through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology(No. 2010-0018847).

  11. Fault-tolerant Sensor Fusion for Marine Navigation

    DEFF Research Database (Denmark)

    Blanke, Mogens

    2006-01-01

    where essential navigation information is provided even with multiple faults in instrumentation. The paper proposes a provable correct implementation through auto-generated state-event logics in a supervisory part of the algorithms. Test results from naval vessels document the performance and shows...... events where the fault-tolerant sensor fusion provided uninterrupted navigation data despite temporal instrument defects...

  12. Remarks on the observability of single beacon underwater navigation

    DEFF Research Database (Denmark)

    Jouffroy, Jerome; Ross, Andrew

    This paper contributes a simple and intuitive result in the analysis of underwater navigation using a single ranging beacon. This analysis should help with the design of small and lightweight underwater vehicles by reducing the amount of instrumentation required for accurate navigation. The concept...

  13. Navigation message designing with high accuracy for NAV

    Institute of Scientific and Technical Information of China (English)

    Wang Luxiao; Huang Zhigang; Zhao Yun

    2014-01-01

    Navigation message designing with high accuracy guarantee is the key to efficient navi-gation message distribution in the global navigation satellite system (GNSS). Developing high accu-racy-aware navigation message designing algorithms is an important topic. This paper investigates the high-accuracy navigation message designing problem with the message structure unchanged. The contributions made in this paper include a heuristic that employs the concept of the estimated range deviation (ERD) to improve the existing well-known navigation message on L1 frequency (NAV) of global positioning system (GPS) for good accuracy service; a numerical analysis approximation method (NAAM) to evaluate the range error due to truncation (RET) of different navigation messages; and a basic positioning parameters designing algorithm in the limited space allocation. Based on the predicted ultra-rapid data from the ultra-rapid data from the international GPS service for geodynamic (IGU), ERDs are generated in real time for error correction. Simulations show that the algorithms developed in this paper are general and flexible, and thus are applicable to NAV improvement and other navigation message designs.

  14. Animal Navigation in the Classroom: Lessons from a Pilot Experience

    Science.gov (United States)

    Fanini, Lucia

    2011-01-01

    In response to a direct request from science teachers, researchers initiated a pilot experience on animal orientation and navigation, which was delivered to 61 13-year-old students in Florence, Italy. The aim was to explain the approach to ethology and to link animal navigation with geography, focusing on species crossing the Italian territory.…

  15. Dead-reckoning/vision integrated navigation for mobile robot

    Institute of Scientific and Technical Information of China (English)

    孙德波

    2003-01-01

    A dead reckoning system and a vision navigation system are proposed for use in a new integrated sys-tem for robot navigation. Since the dead reckoning system uses a recurrence algorithm to determine the position,the position will be divergent in two horizontal directions with time increasing. In order to overcome this defect,a vision navigation system is used to periodically correct the dead reckoning system, and a kalman filter is usedto estimate the errors of navigation and the unknown biases of sensors, and precise position and heading estima-tions are obtained by updating navigation errors and sensors' biases. It is concluded from the simulation resultsthat all the navigation parameters can be obtained through kalman filtering, and the integrated navigation systemproposed for robot navigation can be used in an actual robot working in a laboratory. The measurement noise a-nalysis shows that with the distance between beacon and robot increasing, the measurement noise will increase,and in order to achieve a proper estimation accuracy, the distance should not be too great.

  16. Autonomous Navigation of Small Uavs Based on Vehicle Dynamic Model

    Science.gov (United States)

    Khaghani, M.; Skaloud, J.

    2016-03-01

    This paper presents a novel approach to autonomous navigation for small UAVs, in which the vehicle dynamic model (VDM) serves as the main process model within the navigation filter. The proposed method significantly increases the accuracy and reliability of autonomous navigation, especially for small UAVs with low-cost IMUs on-board. This is achieved with no extra sensor added to the conventional INS/GNSS setup. This improvement is of special interest in case of GNSS outages, where inertial coasting drifts very quickly. In the proposed architecture, the solution to VDM equations provides the estimate of position, velocity, and attitude, which is updated within the navigation filter based on available observations, such as IMU data or GNSS measurements. The VDM is also fed with the control input to the UAV, which is available within the control/autopilot system. The filter is capable of estimating wind velocity and dynamic model parameters, in addition to navigation states and IMU sensor errors. Monte Carlo simulations reveal major improvements in navigation accuracy compared to conventional INS/GNSS navigation system during the autonomous phase, when satellite signals are not available due to physical obstruction or electromagnetic interference for example. In case of GNSS outages of a few minutes, position and attitude accuracy experiences improvements of orders of magnitude compared to inertial coasting. It means that during such scenario, the position-velocity-attitude (PVA) determination is sufficiently accurate to navigate the UAV to a home position without any signal that depends on vehicle environment.

  17. The use of navigation systems in naturalistic driving.

    NARCIS (Netherlands)

    Knapper, A. Nes, C.N. van Christoph, M.W.T. Hagenzieker, M.P. & Brookhuis, K.A.

    2015-01-01

    In this study we assessed the use of portable navigation systems in everyday driving by applying in-vehicle naturalistic driving. Experienced users of navigation systems, seven female and fourteen male, were provided with a specially equipped vehicle for approximately one month. Their trips were rec

  18. The use of navigation systems in naturalistic driving

    NARCIS (Netherlands)

    Knapper, Allert; Van Nes, Nicole; Christoph, Michiel; Hagenzieker, Marjan; Brookhuis, Karel

    2016-01-01

    Objective: In this study, we assessed the use of portable navigation systems in everyday driving by applying in-vehicle naturalistic driving. Method: Experienced users of navigation systems, 7 females and 14 males, were provided with a specially equipped vehicle for approximately 1 month. Their trip

  19. High Speed Lunar Navigation for Crewed and Remotely Piloted Vehicles

    Science.gov (United States)

    Pedersen, L.; Allan, M.; To, V.; Utz, H.; Wojcikiewicz, W.; Chautems, C.

    2010-01-01

    Increased navigation speed is desirable for lunar rovers, whether autonomous, crewed or remotely operated, but is hampered by the low gravity, high contrast lighting and rough terrain. We describe lidar based navigation system deployed on NASA's K10 autonomous rover and to increase the terrain hazard situational awareness of the Lunar Electric Rover crew.

  20. The impact of navigation systems on traffic safety

    NARCIS (Netherlands)

    Rooijen, T. van; Vonk, T.

    2007-01-01

    This paper studies the impact of navigation systems on traffic safety in the Netherlands. This study consists of four analyses: a literature survey, a database analysis, a user survey and an instrumented vehicle study. The results of the four sections show that navigation systems have a positive eff