International cooperation and technology transfer

Fras, Mojca Kosmatin

Bibliographic data

Monograph

Persistent identifier:: 856490555

Author:: Fras, Mojca Kosmatin

Title:: International cooperation and technology transfer

Sub title:: Ljubljana, Slovenia, February 2 - 5, 2000 : proceedings of the workshop

Scope:: VI, 163 Seiten

Year of publication:: 2000

Place of publication:: London

Publisher of the original:: RICS Books

Identifier (digital):: 856490555

Illustration:: Illustrationen, Diagramme

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: HIGHWAY SURVEYING WITH DGPS BASED ON RTCM SATELLITE CORRECTIONS. S. COSSI, M. MARSELLA, C. NARDINOCCHI, L. TOMBOLINI

Document type:: Monograph

Structure type:: Chapter

36 Figure 9 Observed linear trend in the difference of mile chaînage values Figure 10 Comparison of the mile chainage measured by the odometer in moving and Stop&Go mode. 4.3 Comparison between GPS and odometer From the GPS co-ordinates a mile chainage was computed in correspondence of every reference point. Different procedures for extracting the mile chainage from the 3D co-ordinates were carefully evaluated. The results achievable with different approaches strongly depend on GPS data acquisition interval, the speed of the vehicle, the regularity of the trajectory and of course, the accuracy of the GPS co-ordinates. In particular, the procedure for computing the mile chainage by accumulating the length of the differential vectors between two subsequent instantaneous positions of the vehicle was firstly applied. The results show that only with accurate data (dual frequency Post- Processed) the mile chainage estimates can be considered reliable for positioning also along very irregular paths. In general, when dealing with meter accuracy data the cumulative procedure results in the accumulation of the errors, too. A simple approach to reduce the accumulated error is to use the minimum number of GPS positions necessary to describe the variation of trajectory from a straight line. To satisfy more stringent requirements accurate and dense data can be adopted in a smoothing procedure with the aim of limiting the errors in the mile chainage. In this work in consideration of the regularity of the speed of the vehicle and the highway path, a simple approach, based on selecting no more than ten GPS positions every kilometre was adopted for mile chainage extracting. In the following the mile chainage measured by the odometer working in Stop&Go mode are taken as reference values. Figure 11 shows the results obtained from the comparison of the Stop&Go GPS mile chainages and the reference values. Figure 11 Comparison between the mile chainage measured in Stop&Go mode by GPS receivers and the reference values. The systematic effect of about 3 meters can be explained by an overestimation of the GPS mile chainage due to residual cumulative errors. In order to obtain better results from the dual frequency GPS data, a dedicated fitting procedure has to be implemented, eventually including also the integration of data from other sensors. In order to analyse the quality of positioning in a normal operational environment the results from data collected in dynamic mode are compared. The comparison between the mile chainage measured in RTCM and Post-Processed mode by Pro XR/XRS GPS receiver and the odometric mile chainage (Figure 12) shows the same situation discussed before. Figure 12 Comparison between the mile chainage measured in Stop&Go mode by GPS Pro XR/XRS receiver and the odometric mile chainage. 4.5 A configuration of a GPS based Positioning system for road survey The experience gained during the field tests has been utilised for designing an optimal hardware and software configuration for a GPS-based positioning system, shown in Figure 13. The proposed configuration refers to the receivers and softwares adopted in the experiments (Trimble) and includes both Real- Time and Post-Processing positional capabilities.

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