Precise GPS Position and Attitude
Authors
Petrovskyy, Volodymyr ; Tretyak, Vyacheslav
Term
10. term
Publication year
2007
Pages
74
Abstract
This project addresses the increasing need for precise GPS positioning by developing and evaluating software for post-processed determination of both position and attitude (roll, pitch, yaw) for a moving tractor. The report reviews key GPS error sources (ephemerides, satellite and receiver clocks, ionosphere, troposphere, multipath) and signal structure and components, and implements a software receiver with acquisition, tracking, and data decoding for C/A and carrier-phase observations. Positioning algorithms include point and differential methods with single and double differences, ambiguity resolution, cycle slip detection and repair, and Kalman filtering; attitude is estimated within defined coordinate frames. Field data from the tractor were processed, yielding position accuracy of about one centimeter and attitude accuracy around 0.5°. A practical limitation was that phase-locked loop (PLL) carrier frequency accuracy in the tracking channels reduced the carrier-phase–based positioning accuracy relative to code-phase observations within the implemented software receiver.
Dette projekt adresserer det stigende behov for præcis GPS-positionering ved at udvikle og evaluere software til postprocesseret bestemmelse af både position og attitude (roll, pitch, yaw) for en kørende traktor. Rapporten gennemgår centrale fejlkilder i GPS (efemerider, satellit- og modtagerure, ionosfære, troposfære, multipath) samt signalstruktur og komponenter, og implementerer en softwaremodtager med acquisition, tracking og datadekodning for C/A- og carrier-fase observationer. Positionsberegningen omfatter punkt- og differentialmetoder med enkelt- og dobbeltforskelle, ambiguitetsløsning, detektion og reparation af cykelspring samt Kalman-filtrering; attitude estimeres i definerede koordinatrammer. Feltdata fra traktoren er efterbehandlet og gav en positionsnøjagtighed omkring én centimeter og en attitudenøjagtighed på cirka 0,5°. En praktisk begrænsning var, at fase-låst loop (PLL) carrier-frekvensnøjagtighed i trackingkanalerne reducerede præcisionen af carrier-fasebaseret positionering i forhold til kode-fase observationer i den implementerede softwaremodtager.
[This apstract has been generated with the help of AI directly from the project full text]