Observability Analysis of an Inertial Navigation System with Stationary Updates

Stationary measurement updates offer the possibility of containing errors in velocity, biases and attitude even during periods of GPS unavailability, given the information that the rover is not moving. Automated detection of appropriate instances of stationarity is possible, given a recently proposed frequency domain method based on IMU data. In this paper we focus on analytical and numerical evaluation of observability of error states of an INS aided with stationary updates. The null space of the continuous time observability gramian is evaluated for various motion scenarios typically occurring in a land vehicle.