Browsing by Author "Li, Tao"

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    Ultra-tightly coupled high sensitivity gps receiver for on-road vehicular applications
    (2012) Li, Tao; Lachapelle, Gérard; Petovello, Mark
    For on-road vehicular navigation applications, High Sensitivity GPS (HSGPS) receivers are usually preferable to improve signal acquisition and tracking capabilities in comparison to conventional GPS receivers that suffer degraded performance or may completely fail to operate. Vehicle sensors can provide aiding information to bridge the gaps and thus improve the continuity and reliability of the navigation system. Therefore, this thesis focuses on ultra-tightly coupling of HSGPS receivers and vehicle sensors for improved navigation performance. A block estimator based HSGPS receiver is developed with improved tracking sensitivity. The receiver uses a block of correlators for GPS signal parameter estimation and a vector based tracking strategy. Up to 100 ms coherent integration time is used in the receiver to improve the sensitivity with external data bit aiding. The performance of the receiver is analyzed in both the positioning and tracking domain, which provides the basis for the design of an innovative ultra-tightly coupled GPS receiver. To integrate vehicle sensors, improved dead reckoning (DR) based integration algorithms are proposed in this research to provide better navigation performance. Vehicle sideslips, pitch and roll dynamics, usually ignored in previous research are also taken into consideration in this work. Field test results show that the accuracy of 2.4% of travelled distance can be obtained using the proposed algorithm. The performance of the integrated system with various sensor configurations is also analyzed in different environments. Furthermore, a novel DR based in-motion alignment algorithm is proposed to initialize low cost reduced Inertial Measurement Units (IMUs). The new in-motion alignment algorithm features five-degree alignment accuracy within 20 seconds, without initial knowledge of the attitude. Finally a new ultra-tightly coupled GPS receiver based on the block estimator and DR integration algorithms is proposed and developed. The performance of the receiver is comprehensively analyzed in different environments. The field test results shows that the receiver provides within a RMS positioning accuracy within five metres even in deep urban canyon environments, which meets the requirement for most vehicular navigation applications.
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    Use of wheel speed sensors to enhance a reduced imu ultra-tight gnss receiver
    (2009) Li, Tao; Lachapelle, Gérard; Petovello, Mark