Читать книгу Global Navigation Satellite Systems, Inertial Navigation, and Integration - Mohinder S. Grewal - Страница 149

Unaided inertial navigators are essentially integrators, integrating sensed accelerations (including sensor noise) to get velocity and integrating velocity to get position. Unfortunately, integration does bad things to zero‐mean random noise. The integral of zero‐mean additive uncorrelated random noise on an accelerometer output is a random walk process, the variance of which grows linearly over time. Integrated twice to get position, we might expect variance to grow quadratically with time, in which case its standard deviation would grow linearly with time. As a consequence, one might expect INS performance to be characterized by how fast an error distance statistic grows linearly with time.