| Summary: | 碩士 === 國立臺灣海洋大學 === 通訊與導航工程學系 === 101 === This thesis investigates the GPS tracking loop designs using the interactive multiple model (IMM) unscented Kalman filter (UKF). The research work covers two parts: (1) the UPF-based tracking loop design with multipath parameter estimation; and (2) the vector tracking loop design based on the IMM UKF.
Most of the conventional approach for code synchronization process employs the Delay Locked Loop (DLL) structure. The conventional DLL loop uses a discriminator function constructed with a specific combination of its early, prompt, and late correlator to detect code tracking error. Multipath is one of the dominant error sources in the GPS positioning. One of the most important tasks is the interference suppression techniques. In the first part of this thesis, an interactive multiple model nonlinear filter algorithm is designed, where the code tracking loop with multipath parameter estimation is involved. The second part of this thesis is to apply the IMM nonlinear filtering on GPS vector tracking loop designs to reduce the position error under high dynamic environments. The unscented Kalman filter (UKF) employs a set of sigma points through deterministic sampling, such that the linearization process is not necessary, and therefore the error caused by linearization as in the traditional extended Kalman filter (EKF) can be avoided. The interacting multiple model (IMM) describes a set of switching models, finally provides the suitable value of process noise covariance.
The proposed IMMUKF algorithm shows remarkable improvement in navigation estimation accuracy as compared to the conventional approaches.
|
|---|
