Bernhard Hofmann-Wellenhof

Bio: Bernhard Hofmann-Wellenhof is an academic researcher from Graz University of Technology. The author has contributed to research in topics: Global Positioning System & GNSS applications. The author has an hindex of 9, co-authored 18 publications receiving 3130 citations.

Global Positioning System: Theory and Practice

Abstract: 1 Introduction- 11 The origins of surveying- 12 Development of global surveying techniques- 121 Optical global triangulation- 122 Electromagnetic global trilateration- 13 History of the Global Positioning System- 131 Navigating with GPS- 132 Surveying with GPS- 2 Overview of GPS- 21 Basic concept- 22 Space segment- 221 Constellation- 222 Satellites- 223 Operational capabilities- 224 Denial of accuracy and access- 23 Control segment- 231 Master control station- 232 Monitor stations- 233 Ground control stations- 24 User segment- 241 User categories- 242 Receiver types- 243 Information services- 3 Reference systems- 31 Introduction- 32 Coordinate systems- 321 Definitions- 322 Transformations- 33 Time systems- 331 Definitions- 332 Conversions- 333 Calendar- 4 Satellite orbits- 41 Introduction- 42 Orbit description- 421 Keplerian motion- 422 Perturbed motion- 423 Disturbing accelerations- 43 Orbit determination- 431 Keplerian orbit- 432 Perturbed orbit- 44 Orbit dissemination- 441 Tracking networks- 442 Ephemerides- 5 Satellite signal- 51 Signal structure- 511 Physical fundamentals- 512 Components of the signal- 52 Signal processing- 521 Receiver design- 522 Processing techniques- 6 Observables- 61 Data acquisition- 611 Code pseudoranges- 612 Phase pseudoranges- 613 Doppler data- 614 Biases and noise- 62 Data combinations- 621 Linear phase combinations- 622 Code pseudorange smoothing- 63 Atmospheric effects- 631 Phase and group velocity- 632 Ionospheric refraction- 633 Tropospheric refraction- 634 Atmospheric monitoring- 64 Relativistic effects- 641 Special relativity- 642 General relativity- 643 Relevant relativistic effects for GPS- 65 Antenna phase center offset and variation- 66 Multipath- 661 General remarks- 662 Mathematical model- 663 Multipath reduction- 7 Surveying with GPS- 71 Introduction- 711 Terminology definitions- 712 Observation techniques- 713 Field equipment- 72 Planning a GPS survey- 721 General remarks- 722 Presurvey planning- 723 Field reconnaissance- 724 Monumentation- 725 Organizational design- 73 Surveying procedure- 731 Preobservation- 732 Observation- 733 Postobservation- 734 Ties to control monuments- 74 In situ data processing- 741 Data transfer- 742 Data processing- 743 Trouble shooting and quality control- 744 Datum transformations- 745 Computation of plane coordinates- 75 Survey report- 8 Mathematical models for positioning- 81 Point positioning- 811 Point positioning with code ranges- 812 Point positioning with carrier phases- 813 Point positioning with Doppler data- 82 Differential positioning- 821 Basic concept- 822 DGPS with code ranges- 823 DGPS with phase ranges- 83 Relative positioning- 831 Phase differences- 832 Correlations of the phase combinations- 833 Static relative positioning- 834 Kinematic relative positioning- 835 Pseudokinematic relative positioning- 9 Data processing- 91 Data preprocessing- 911 Data handling- 912 Cycle slip detection and repair- 92 Ambiguity resolution- 921 General aspects- 922 Basic approaches- 923 Search techniques- 924 Ambiguity validation- 93 Adjustment, filtering, and smoothing- 931 Least squares adjustment- 932 Kalman filtering- 933 Smoothing- 94 Adjustment of mathematical GPS models- 941 Linearization- 942 Linear model for point positioning with code ranges- 943 Linear model for point positioning with carrier phases- 944 Linear model for relative positioning- 95 Network adjustment- 951 Single baseline solution- 952 Multipoint solution- 953 Single baseline versus multipoint solution- 954 Least squares adjustment of baselines- 96 Dilution of precision- 97 Accuracy measures- 971 Introduction- 972 Chi-square distribution- 973 Specifications- 10 Transformation of GPS results- 101 Introduction- 102 Coordinate transformations- 1021 Cartesian coordinates and ellipsoidal coordinates- 1022 Global coordinates and local level coordinates- 1023 Ellipsoidal coordinates and plane coordinates- 1024 Height transformation- 103 Datum transformations- 1031 Three-dimensional transformation- 1032 Two-dimensional transformation- 1033 One-dimensional transformation- 104 Combining GPS and terrestrial data- 1041 Common coordinate system- 1042 Representation of measurement quantities- 11 Software modules- 111 Introduction- 112 Planning- 113 Data transfer- 114 Data processing- 115 Quality control- 116 Network computations- 117 Data base management- 118 Utilities- 119 Flexibility- 12 Applications of GPS- 121 General uses of GPS- 1211 Global uses- 1212 Regional uses- 1213 Local uses- 122 Attitude determination- 1221 Theoretical considerations- 1222 Practical considerations- 123 Airborne GPS for photo-control- 124 Interoperability of GPS- 1241 GPS and Inertial Navigation Systems- 1242 GPS and GLONASS- 1243 GPS and other sensors- 1244 GPS and the Federal Radionavigation Plan- 125 Installation of control networks- 1251 Passive control networks- 1252 Active control networks- 13 Future of GPS- 131 New application aspects- 132 GPS modernization- 1321 Future GPS satellites- 1322 Augmented signal structure- 133 GPS augmentation- 1331 Ground-based augmentation- 1332 Satellite-based augmentation- 134 GNSS- 1341 GNSS development- 1342 GNSS/Loran-C integration- 135 Hardware and software improvements- 1351 Hardware- 1352 Software- 136 Conclusion- References

Global pose estimation using multi-sensor fusion for outdoor Augmented Reality

Abstract: Outdoor Augmented Reality typically requires tracking in unprepared environments. For global registration, Global Positioning System (GPS) is currently the best sensing technology, but its precision and update rate are not sufficient for high quality tracking. We present a system that uses Kalman filtering for fusion of Differential GPS (DGPS) or Real-Time Kinematic (RTK) based GPS with barometric heights and also for an inertial measurement unit with gyroscopes, magnetometers and accelerometers to improve the transient oscillation. Typically, inertial sensors are subjected to drift and magnetometer measurements are distorted by electro-magnetic fields in the environment. For compensation, we additionally apply a visual orientation tracker which is drift-free through online mapping of the unknown environment. This tracker allows for correction of distortions of the 3-axis magnetic compass, which increases the robustness and accuracy of the pose estimates. We present results of applying this approach in an industrial application scenario.

GPS-less low-cost outdoor localization for very small devices

Abstract: Instrumenting the physical world through large networks of wireless sensor nodes, particularly for applications like environmental monitoring of water and soil, requires that these nodes be very small, lightweight, untethered, and unobtrusive. The problem of localization, that is, determining where a given node is physically located in a network, is a challenging one, and yet extremely crucial for many of these applications. Practical considerations such as the small size, form factor, cost and power constraints of nodes preclude the reliance on GPS of all nodes in these networks. We review localization techniques and evaluate the effectiveness of a very simple connectivity metric method for localization in outdoor environments that makes use of the inherent RF communications capabilities of these devices. A fixed number of reference points in the network with overlapping regions of coverage transmit periodic beacon signals. Nodes use a simple connectivity metric, which is more robust to environmental vagaries, to infer proximity to a given subset of these reference points. Nodes localize themselves to the centroid of their proximate reference points. The accuracy of localization is then dependent on the separation distance between two-adjacent reference points and the transmission range of these reference points. Initial experimental results show that the accuracy for 90 percent of our data points is within one-third of the separation distance. However, future work is needed to extend the technique to more cluttered environments.

Handbook of Marine Craft Hydrodynamics and Motion Control: Fossen/Handbook of Marine Craft Hydrodynamics and Motion Control

Abstract: The technology of hydrodynamic modeling and marine craft motion control systems has progressed greatly in recent years. This timely survey includes the latest tools for analysis and design of advanced guidance, navigation and control systems and presents new material on underwater vehicles and surface vessels. Each section presents numerous case studies and applications, providing a practical understanding of how model-based motion control systems are designed.

Principles of GNSS, Inertial, and Multi-Sensor Integrated Navigation Systems

Abstract: Navigation systems engineering is a red-hot area. More and more technical professionals are entering the field and looking for practical, up-to-date engineering know-how. This single-source reference answers the call, providing both an introduction to overall systems operation and an in-depth treatment of architecture, design, and component integration. This book explains how satellite, on-board, and other navigation technologies operate, and it gives practitioners insight into performance issues such as processing chains and error sources. Providing solutions to systems designers and engineers, the book describes and compares different integration architectures, and explains how to diagnose errors. Moreover, this hands-on book includes appendices filled with terminology and equations for quick referencing.

Localization for mobile sensor networks

Abstract: Many sensor network applications require location awareness, but it is often too expensive to include a GPS receiver in a sensor network node. Hence, localization schemes for sensor networks typically use a small number of seed nodes that know their location and protocols whereby other nodes estimate their location from the messages they receive. Several such localization techniques have been proposed, but none of them consider mobile nodes and seeds. Although mobility would appear to make localization more difficult, in this paper we introduce the sequential Monte Carlo Localization method and argue that it can exploit mobility to improve the accuracy and precision of localization. Our approach does not require additional hardware on the nodes and works even when the movement of seeds and nodes is uncontrollable. We analyze the properties of our technique and report experimental results from simulations. Our scheme outperforms the best known static localization schemes under a wide range of conditions.

Scattering of GPS signals from the ocean with wind remote sensing application

Abstract: A theoretical model that describes the power of a scattered Global Positioning System (GPS) signal as a function of geometrical and environmental parameters has been developed. This model is based on a bistatic radar equation derived using the geometric optics limit of the Kirchhoff approximation. The waveform (i.e., the time-delayed power obtained in the delay-mapping technique) depends on a wave-slope probability density function, which in turn depends on wind. Waveforms obtained for aircraft altitudes and velocities indicate that altitudes within the interval 5-15 km are the best for inferring wind speed. In some regimes, an analytical solution for the bistatic radar equation is possible. This solution allows converting trailing edges of waveforms into a set of straight lines, which could be convenient for wind retrieval. A transition to satellite altitudes, together with satellite velocities, makes the peak power reduction and the Doppler spreading effect a significant problem for wind retrieval based on the delay-mapping technique. At the same time, different time delays and different Doppler shifts of the scattered GPS signal could form relatively small spatial cells on sea surface, suggesting mapping of the wave-slope probability distribution in a synthetic-aperture-radar (SAR) fashion. This may allow more accurate measurements of wind velocity and wind direction.