Tightly coupled GPS/INS integration for differential carrier phase navigation systems using decentralized estimation

Much research has been conducted in the area of tightly coupled GPS/INS, and this work has resulted in a vast array of navigation algorithms. A common theme of these methods is that they operate on low rate GPS ranging measurements of code and carrier phase together with high rate raw inertial measurements, such as specific force and inertial angular velocity. For stand-alone (i.e., non-differential) GPS navigation applications, high data rate INS outputs can be properly accommodated with today's computer processors. For relative (i.e., differential) GPS navigation applications, the optimal analogous solution would be for the mobile user to have access to the reference station's raw inertial measurements along with its own. However, due to communication bandwidth limitations, it is generally not possible to broadcast high data rate inertial navigation data. In response, an alternative tightly-coupled, differential GPS/INS navigation system is developed here using a decentralized Kalman filtering approach, which can operate at manageable broadcast data rates.