Читать книгу Global Navigation Satellite Systems, Inertial Navigation, and Integration - Mohinder S. Grewal - Страница 119

This is only possible with gimbaled systems and it adds to the start‐up time, but it can improve performance. Navigation accuracy is very sensitive to accelerometer biases, which can shift due to thermal transients in turn‐on/turn‐off cycles, and can also drift randomly over time for some accelerometer design. Fortunately, gimbals can be used to calibrate accelerometer biases in a stationary 1g environment. Bias and scale factors can both be determined by using the gimbals to point each accelerometer input axes straight up and then straight down (by nulling the horizontal accelerometer outputs). Then each accelerometer's bias is the average of the up and down outputs and scale factor is half the difference divided by the local gravitational acceleration.