Ultra-tight GPS/INS Integrated System for Land Vehicle Navigation in Challenging Environments
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The Global Navigation Satellite Systems (GNSS) have been commonly used for land vehicle positioning and navigation applications. A typical example of GNSS is the Global Positioning System (GPS). The GPS provides accurate navigation solution in open sky. However, in some circumstances, such as urban areas, underpasses, tunnels, and in the presence of signal jamming, GPS signals cannot be easily tracked since they might be harshly attenuated or entirely blocked, potentially leading to loss of signal, thereby requiring re-acquisition of the signal for the corresponding satellite. To avoid the intensive computations necessary for the signal re-lock (i.e., signal re-acquisition stage) in a GPS receiver, a robust signal-tracking mechanism that can hold and/or rapidly re-lock on the signals and keep track of their dynamics is becoming necessary. Additionally, the signal tracking process is where measurements are generated; thus, it has a direct impact on the resultant navigation solution. This makes the choice of a successful tracking method a crucial task in GPS receiver design. The significance of research in this thesis is multi-fold. First, is the design and implementation of a robust vector-based tracking system which furthermore required the realization of a complete software-defined receiver (SDR). Second, the proposed tracking system architecture was augmented with a reduced inertial navigation system (RISS) to produce a new ultra-tight GPS/INS integrated system that further enhances a receivers tracking robustness and sensitivity in challenging scenarios. Third, this research also presents a more computationally efficient inertial measurement unit (IMU) data de-noising method. Last but not the least, this thesis also presents a novel GPS/INS trajectory data simulation podium that can generate simulation data sets for all levels of GPS/INS integration systems. This tool was successfully used to verify the operation and performance of the newly implemented ultra-tight GPS/INS integrated system. Results show a good performance of the implemented method(s) against a commercial receiver and a reference solution. The software receiver approach has been adopted as a platform for implementing the proposed algorithm(s); nevertheless, the proposed methodology can be applied in conventional hardware receivers, as well.