摘要:

ABSTRACTThe tragic loss of an Air India jetliner off the coast of Ireland on June 21, 1985 resulted in an operation that illustrated the state‐of‐the‐art systems and techniques used in deep ocean integrated positioning and navigation. The aircraft debris was spread over a 30 mi2stretch of ocean, in depths of over 6,700 ft. The search and recovery effort required the use of both subsea and surface‐based navigation equipment for accurately logging the positions of hundreds of pieces of debris.A microcomputer‐based integrated navigation system (called ALLNAV), engineered, built, and operated by Eastport International, was used as the primary navigation system. ALLNAV was used for positioning the SCARAB Remotely Operated Vehicle, working on the seafloor, and the support ship, JOHN CABOT, above. With the integrated navigation system processing both acoustic positioning data and radio positioning data, the lat/long locations of all located debris were determined.This paper will address the requirements of, and equipment and techniques used for, subsea integrated navigation. The application of integrated navigation equipment on the Air India operation will be used as a cas

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1988.tb00936.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTEvolution of the inertial sensor element for aircraft navigation applications over the last three decades has happened in many areas. Volume/weight has decreased, performance/reliability has increased, and support electronics capability has increased by an order of magnitude. A rotating wheel iron gyro‐based sensor element now weighs 8 lb and performs to an accuracy of 0.1 to 0.8 nmi/h. The Ring Laser Gyro‐based sensor element has been introduced over the last decade. The first generation Ring Laser Gyro sensor element weighs 20 lb and performs better than 0.8 nmi/h. Significant reliability improvements are projected for this technology.This paper describes a second generation Ring Laser Gyro that will reduce weight to that of the iron gyro‐based system. A brief description of the instrument is provided along with flight test data accumulated on the unit. Use of an advanced digital signal processor electronics architecture is discussed as a companion development to reduce system weight/volume and to further increase reliab

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1988.tb00937.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTAn Integrity Working Group was formed on April 22, 1986 by RTCA Special Committee‐159 to investigate and report on civil integrity problems relating to the use of the Global Positioning System by civil aviation. Although the self‐checking and warning features built into GPS are adequate to meet military integrity requirements and to allow safe operation of DoD aircraft, more stringent safety requirements must be met for GPS to receive FAA approval for use by civil aviation in the National Airspace System.To establish integrity alarm limits and time‐to‐alarm requirements for GPS, the Integrity Working Group examined existing requirements already established for other navigation systems. A variety of GPS integrity monitoring techniques were then studied to determine for which phases of flight they would provide sufficient integrity to allow use of GPS by civil aviation. This paper summarizes the conclusions and recommendations of the Integrity Workin

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1988.tb00938.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTPrevious approaches to the self‐contained GPS integrity problem have been in a hypothesis testing setting where the two hypotheses are: (1) a single satellite has failed, or (2) there is no failure. In this setting, selective availability is the major source of noise that impedes the detection scheme's ability to detect failures and, at the same time, have a low false alarm rate. This paper poses the problem in a different setting where the basic questions posed are: (1) is the radial position error less than some preset bound? or (2) is it greater than that bound? This is a more fundamental approach, because the pilot does not really care where the error comes from; rather, he is only concerned that the radial position error does not exceed a certain specified level. Results of simulations using a 24‐satellite constellation and maximum separation of redundant solutions as the test statistic are presented. These results indicate that this scheme could provide radial error protection of about 250 m with acceptably low alarm and miss ra

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1988.tb00939.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTThe U.S. Coast Guard has a research program to investigate the capability of C/A‐code GPS and methods to improve its accuracy and integrity. A differential GPS demonstration system is being assembled and tested at the U.S. Coast Guard Research and Development Center in Groton, Connecticut. Analysis of static and dynamic testing is discussed. Details of instrumentation supporting the test program are also presente

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1988.tb00940.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTThe objectives of the Canadian Hydrographic Service with respect to GPS utilization are reviewed. A shipborne experiment undertaken in November 1986 and designed to test techniques developed to fulfill some of these objectives is described. The primary purpose of the experiment was to assess the performance of differential GPS positioning on a 10 m survey launch. The techniques utilized and results obtained on the launch are described. Additional tests conducted on a 38 m vessel are summarized. TI4100 GPS receivers were used in various combinations of P code, C/A code, and different user dynamics modes. Carrier phase measurements were combined with pseudoranges to improve the accuracy. The reference positions were provided by two Atlas Polarfix systems and a Mini‐Ranger Falcon 484 system. The external horizontal position accuracy of differential GPS was estimated to be 4.5 m at the 95 percent confidence level. Initial results obtained with a low cost attitude sensor are compared with GPS for both the launch and the 38 m vessel. The use of GPS to estimate heave motion is also discussed. Prospects of further improving GPS accuracy for shipborne positioning are mentioned in the conclusion

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1988.tb00941.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTA closed‐form solution of the GPS pseudorange equations, an unaided Kalman filter, and an inertially‐aided Kalman filter are used with differential GPS postprocessing to produce reference trajectories for evaluation of GPS user‐equipment, for evaluation of integrated host vehicle navigation, and for accurate Time Space Position Information over large operating areas.The closed‐form solution was developed in a derivation of existence conditions for solutions to GPS pseudorange equations. The derivation is included here as an Appendix. Positions calculated from the closed‐form solution are used for starting and monitoring the Kalman filters, and for responding to uploads and constellation changes. Custom interface modules adapt common core modules of the aided Kalman filter to various inertial n

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1988.tb00942.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTMany inertial navigation systems of both platform and ring laser strapdown types are currently in service. This paper discusses the possibility and desirability of incorporating a small GPS receiver in these systems. Advances in technology such as microprocessors, gate arrays, and surface mount devices allow the existing INS electronics to be replaced in a reduced volume. The remaining space in many cases is sufficient to permit the insertion of a small GPS receiver.Locating the GPS receiver in an inertial navigation system (INS) solves many of the usual system integration problems. Tight coupling between the GPS and INS can be achieved since data latency is minimized and well controlled. In such a configuration, rate aiding of the GPS is easily achieved. This approach also leads to greater flexibility and enhanced overall performance since all GPS and INS data are simultaneously available.While not providing the ultimate in redundancy, the integrated INS/GPS approach does offer greater simplicity with enhanced performance. This discussion primarily focuses on military systems. Nevertheless, the proposed techniques also are applicable to commercial units.

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1988.tb00943.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTDevelopment and testing of a prototype GPS receiver housed in a commercial inertial reference system has recently been completed. A flight test program in 1986 demonstrated dynamic performance in maneuvering flight, operation in low signal/noise environments, and operation at zero degree satellite elevation angles with 20–30 m typical accuracies using the Block I GPS satellites. The effects of altitude and clock aiding were also demonstrated.Many of the recognized limitations of an inertial system (including unbounded position error and pilot initialization as well as stand‐alone GPS limitations such as poor satellite geometry, dynamic noise and satellite masking) are overcome with this integrated design approach. This paper describes the advantages of GPS/IRS integration as well as a design approach that utilizes them. The paper also summarizes some test results of the prototype GPS recei

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1988.tb00944.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Book reviewed in this article:THE SEXTANT HANDBOOK Bruce Bauer, International Marine PublishersELECTRONIC AIDS TO NAVIGATION L. Tetley and D. Calcutt

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1988.tb00945.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY