Observability analysis of the INS/GPS navigation system on the measurements in land vehicle applications

In this paper, the observability of the INS/GPS navigation system for a land vehicle is analyzed on measurements and different dimension filters with respect to the measurements are designed. In the stationary case, it is shown that the horizontal accelerometer biases and vertical attitude errors and gyro biases are unobservable. An 8th filter is designed based on the observability analysis. When GPS signal is available, a 15th filter is used with position and velocity measurements. To estimate the INS errors even in the case that GPS signal is blocked a filter is designed in consideration of the non-holonomic constraints of a land vehicle. In this case, the horizontal position and velocity errors and vertical attitude error are unobservable. However, a 12th filter including the velocity states is designed to estimate the accelerometer biases. Based on the results of the observability analysis and the different dimension filters, an efficient INS/GPS filter including the filters as sub-filters can be designed.