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    A test-bed simulator for gps and gis integrated navigation and positioning research: - bus positioning, using gps observations, odometer readings and map matching


    Li, Jing and Taylor, George and Brunsdon, Chris and Olden, Andrew and Steup, Dorte and Winter, Marylin (2004) A test-bed simulator for gps and gis integrated navigation and positioning research: - bus positioning, using gps observations, odometer readings and map matching. Proceedings of the 12th International Conference on Geoinformatics-Geospatial Information Research: Bridging the Pacific and Atlantic.

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    Abstract

    A test-bed application, called Map Matched GPS (MMGPS) processes raw GPS output data, from RINEX files, or GPS derived coordi nates. This developed method uses absolute GPS positioning, map matched, to locate the vehicle on a road centre-line, when GPS is known to be sufficiently accurate. MMGPS software has now been adapted to incorporate positioning based on odometer derived dist ances (OMMGPS), when GPS positions are not available. Relative GPS positions are used to calibrate the odometer observations. In OMMGPS, GPS pseudorange observations are combined with DTM height information and odometer positions to provide a vehicle position at one second epochs. Generally, odometer positioning is used much more often, to position the vehicle, than GPS. Typically the ratio is 7:3 odometer positions to GPS pos itions. In total, over 15,000 vehicle positions were computed using OMMGPS. The described experiment used GPS observations taken on a bus on a predefined route, hence the correct road is always known. Ther efore, map matching techniques are used to improve the GPS positioning accuracy, and to identify grossly inaccurate GPS positions. Calibrated odometer corrections are made using odometer count at the current epoch and relative GPS distance travelled. If a GPS position is detected to be inaccurate, it is not used for positioning the bus, or for calibrating the odometer correction factor. In general the position quality provided by GPS alone was extremely poor, due to multipath effects caused by the urban canyons of central London. In the case of one particular trip, OMMGPS provides a mean error of position of 8.8 metres compared with 53.7 metres for raw GPS alone.

    Item Type: Article
    Keywords: test-bed simulator; gps; gis; integrated navigation; positioning research; bus positionin; gps observations; odometer readings; map matching;
    Academic Unit: Faculty of Science and Engineering > Research Institutes > National Centre for Geocomputation, NCG
    Item ID: 6154
    Depositing User: Prof. Chris Brunsdon
    Date Deposited: 26 May 2015 16:26
    Journal or Publication Title: Proceedings of the 12th International Conference on Geoinformatics-Geospatial Information Research: Bridging the Pacific and Atlantic
    Publisher: Geoinfomatics
    Refereed: Yes
    URI:

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