On-the-Fly GPS ambiguity resolution with inertial aiding.

摘要

Ambiguity resolution is the key to precise positioning applications with GPS (Global Positioning System) carrier phase measurements. The objective of this research is to investigate the feasibility of integrating high quality inertial data into GPS On-the-Fly (OTF) ambiguity resolution and cycle slip detection. A key factor to an ambiguity search procedure is the accuracy of the float ambiguities. The superior navigation accuracy over the short term provided by a high quality INS (Inertial Navigation System) can improve the precision of the initial float ambiguities, and the integration of inertial data into the ambiguity filtering process can yield more accurate float ambiguities and thus facilitate the integer search procedure. In this thesis, inertial aiding in the FASF (Fast Ambiguity Search Filtering) ambiguity resolution is examined in theory under three INS/GPS integration scenarios: loose and tight coupling integration in a decentralized filter structure, and an augmented master filter integration in a centralized filter structure. The ambiguity dilution precision (ADOP), which measures the accuracy of the float ambiguities and the size of the search space, is investigated. To evaluate the performance of the algorithms proposed in the thesis two data sets are processed and results are analyzed. It is found that the ADOP is significantly reduced with INS data in all three integration schemas as long as the GPS outage period is less than 30 seconds. The time to fix integers is reduced on average 30%--70% depending on the GPS outage period and the INS/GPS integration strategy. Results also show that tightly coupling and centralized integration outperform the loose coupling approach.