Abstract: The generation mechanism of lever-arm effect, which is an important factor that contributes to the last precision of transfer alignment, is analyzed. In mechanics compensation method, in order to construct lever arm effect, the lever-arm size must be accurately measured. But in practical application, especially under the condition of long lever-arm size, the lever-arm size becomes a momentarily parameter for the added flexibility of the carrier, and so it is difficult to measure the lever-arm size in advance. In view of the difficulty to get the accurate lever-arm size, an online estimation method is proposed and also the corresponding filter is designed, in this method the error of lever-arm size is added as state vector. The observable degree and estimation effect of lever-arm size error in three different moving conditions are compared, and the results indicate that high frequency and big amplitude of angular motion of carrier can improve the estimation accuracy of lever-arm size error, increase the observable degree and cut the estimation time. The simulation result based on the transfer alignment between the master and slave inertial navigations on board shows that the estimation accuracy of lever-arm size can be up to centimeter grade.

Key words: Inertial navigation, Lever-arm effect, Lever-arm size, Observable degree, Transfer alignment