| Three important factors influence the performance of an aided inertial navigation system (INS): the integration architecture; the quality of the inertial measurement unit; the type, availability, frequency, quality and accuracy of the aiding measurements. This thesis includes a review of the Extended Kalman filter as a data fusion tool and of various aided INS integration approaches. The main contributions of this thesis are: (1) Derivation, implementation, and testing of a method to use roadway altitude to aid an INS within the EKF framework. The approach is tested in the lab. (2) Derivation, implementation, and testing of a new approach to aid the CPS carrier phase integer ambiguity process with external measurements. The algorithm is tested using roadway altitude both in the lab and on a moving vehicle. (3) Analysis of problem of aiding the CPS receiver signal acquisition and tracking processes with INS information. For various reasons, this approach could not be implemented nor tested. In the process of this research, to enhance reliability and to facilitate addition of alternative aiding measurements, the previously existing CPS aided INS software was rewritten and extensively tested. The new implementation can flexibly operate with measurements having different accuracy levels (e.g., CPS code, differential CPS code, carrier phase, roadway altitude, and magnetometer). |
