Nonlinear Observer for Tightly Integrated Inertial Navigation Aided by Pseudo-Range Measurements

A modular nonlinear observer for inertial navigation aided by pseudo-range measurements is designed and analyzed. The attitude observer is based on a recent nonlinear complementary filter that uses magnetometer and accelerometer vector measurements to correct the quaternion attitude estimate driven by gyro measurements, including gyro bias estimation. A tightly integrated translational motion observer is driven by accelerometer measurements, employs the attitude estimates, and makes corrections using the pseudo-range and range-rate measurements. It estimates position, range bias errors, velocity and specific force in an earth-fixed Cartesian coordinate frame, where the specific force estimate is used as a reference vector for the accelerometer measurements in the attitude observer. The exponential stability of the feedback interconnection of the two observers is analyzed and found to have a semiglobal region of attraction with respect to the attitude observer initialization and local region of attraction with respect to translational motion observer initialization. The latter is due to linearization of the range measurement equations that is underlying the selection of injection gains by solving a Riccati equation. In typical applications, the pseudo-range equations admit an explicit algebraic solution that can be easily computed and used to accurately initialize the position and velocity estimates. Hence, the limited region of attraction is not seen as a practical limitation of the approach for many applications. Advantages of the proposed nonlinear observer are low computational complexity and a solid theoretical foundation

SOWFIA Project - Work Package 3 Interim Report

The Streamlining of Ocean Wave Farms Impact Assessment (SOWFIA) Project (IEE/09/809/ SI2.558291) is an EU Intelligent Energy Europe (IEE) funded project that draws together ten partners, across eight European countries, who are actively involved with planned wave farm test centres. The SOWFIA project aims to achieve the sharing and consolidation of pan-European experience of consenting processes and environmental and socio-economic impact assessment (IA) best practices for offshore wave energy conversion developments. Studies of wave farm demonstration projects in each of the collaborating EU nations are contributing to the findings. The study sites comprise a wide range of device technologies, environmental settings and stakeholder interests. Through project workshops, meetings, on-going communication and networking amongst project partners, ideas and experiences relating to IA and policy are being shared, and co-ordinated studies addressing key questions for wave energy development are being carried out. The overall goal of the SOWFIA project is to provide recommendations for approval process streamlining and European-wide streamlining of IA processes, thereby helping to remove legal, environmental and socio-economic barriers to the development of offshore power generation from waves. By utilising the findings from technology-specific monitoring at multiple sites, SOWFIA will accelerate knowledge transfer and promote European-wide expertise on environmental and socio-economic impact assessments of wave energy projects. In this way, the development of the future, commercial phase of offshore wave energy installations will benefit from the lessons learned from existing smaller-scale developments

Space Transportation System and associated payloads: Glossary, acronyms, and abbreviations

A collection of acronyms in everyday use concerning shuttle activities is presented. A glossary of terms pertaining to the Space Transportation System is included

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

Space transportation system and associated payloads: Glossary, acronyms, and abbreviations

A collection of some of the acronyms and abbreviations now in everyday use in the shuttle world is presented. It is a combination of lists that were prepared at Marshall Space Flight Center and Kennedy and Johnson Space Centers, places where intensive shuttle activities are being carried out. This list is intended as a guide or reference and should not be considered to have the status and sanction of a dictionary

Beyond key velocity: Continuous sensing for expressive control on the Hammond Organ and Digital keyboards

In this thesis we seek to explore the potential for continuous key position to be used as an expressive control in keyboard musical instruments, and how preexisting skills can be adapted to leverage this additional control. Interaction between performer and sound generation on a keyboard instrument is often restricted to a number of discrete events on the keys themselves (notes onsets and offsets), while complementary continuous control is provided via additional interfaces, such as pedals, modulation wheels and knobs. The rich vocabulary of gestures that skilled performers can achieve on the keyboard is therefore often simplified to a single, discrete velocity measurement. A limited number of acoustical and electromechanical keyboard instruments do, however, present affordances of continuous key control, so that the role of the key is not limited to delivering discrete events, but its instantaneous position is, to a certain extent, an element of expressive control. Recent evolutions in sensing technologies allow to leverage continuous key position as an expressive element in the sound generation of digital keyboard musical instruments. We start by exploring the expression available on the keys of the Hammond organ, where nine contacts are closed at different points of the key throw for each key onset and we find that the velocity and the percussiveness of the touch affect the way the contacts close and bounce, producing audible differences in the onset transient of each note. We develop an embedded hardware and software environment for low-latency sound generation controlled by continuous key position, which we use to create two digital keyboard instruments. The first of these emulates the sound of a Hammond and can be controlled with continuous key position, so that it allows for arbitrary mapping between the key position and the nine virtual contacts of the digital sound generator. A study with 10 musicians shows that, when exploring the instrument on their own, the players can appreciate the differences between different settings and tend to develop a personal preference for one of them. In the second instrument, continuous key position is the fundamental means of expression: percussiveness, key position and multi-key gestures control the parameters of a physical model of a flute. In a study with 6 professional musicians playing this instrument we gather insights on the adaptation process, the limitations of the interface and the transferability of traditional keyboard playing techniques

JPL basic research review

Current status, projected goals, and results of 49 research and advanced development programs at the Jet Propulsion Laboratory are reported in abstract form. Areas of investigation include: aerodynamics and fluid mechanics, applied mathematics and computer sciences, environment protection, materials science, propulsion, electric and solar power, guidance and navigation, communication and information sciences, general physics, and chemistry

Aeronautical Engineering: A continuing bibliography with indexes, supplement 104

This bibliography lists 532 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System in December 1978