Multirate problems in aided inertial navigation systems

The main principal of navigation systems is the determination of a vehicle´s position and velocity relative to some reference coordinate frame. An inertial navigation system (INS) utilizes inertial properties of sensors mounted aboard the vehicle to execute the navigation function. The system accomplishes this task through appropriate processing of the data obtained from acceleration and angular velocity measurements supplied by the inertial sensors. Thus, an appropriately initialized inertial navigation system is capable of continuous determination of vehicle position, velocity and attitude without using any external information. Inertial navigation systems can be unstable; for this reason they are used with some aiding systems. Multirate sampling is a natural feature of almost any aided inertial navigation system. The multirate nature of aided inertial systems is presented and it is shown that this multirate problem finds a natural solution in the framework of Kalman filtering.