University of California Transportation Center

To operate, guide and control vehicles in low visibility conditions, it is critical that the states of the vehicle are accurately estimated, which includes the three dimensional position, velocity, and attitude. This can be accomplished by GPS (Global Positioning System) aided encoder or GPS aided inertial approaches. The overall positioning accuracy of either approach will be determined by the GPS performance. Real-time centimeter accuracy GPS positioning can be achieved using carrier phase measurements. This requires fast and reliable on-the-°y integer ambiguity resolution.

In this dissertation, we focus on resolving GPS ambiguity problem, including both integer ambiguity estimation and integer ambiguity validation. For integer ambiguity estimation, a brief overview of previous work on integer ambiguity resolution is first presented. Then, an improved integer ambiguity resolution method is proposed. Subsequently, simulations and real-world data are presented to demonstrate the effectiveness of the method. We also present integer ambiguity algorithms with auxiliary measurements and algorithms with multiple epoch measurements, both of which are useful in GPS challenging areas. For integer ambiguity validation, a brief overview is first presented, and then analytic discussion and test results on several popular validations methods are studied. Finally we discuss GPS modernization and its effect on integer estimation and validation.