A self-calibration method of inner lever arms for dual-axis rotation inertial navigation systems

In an inertial navigation system (INS), it is generally assumed that three accelerometers in an inertial measurement unit measure the acceleration input at the same point in space. However, there are error vectors between the respective sensitive point of the three accelerometers and the theoretical measurement point, typically termed as inner lever arms (ILAs). In strapdown INS, the ILAs coupled with the carrier's angular motion lead to a decline in navigation accuracy, while for dual-axis rotational INS (RINS), the ILAs coupled with the gimbals' angular motion further introduce new navigation errors. Therefore, the calibration and compensation for the ILAs are important for enhancing the systemic reliability. In this paper, an ILA self-calibration method is proposed by leveraging the rotation gimbals of the RINS. To be able to obtain all the ILA parameters, we establish an error model by considering the ILAs, and design a reasonable rotation scheme to ensure all parameters observable. The simulations and experiments show that the proposed self-calibration method is able to accomplish the rapid and accurate estimation of all the ILAs and the velocity stage and slope errors are greatly corrected after compensation by the calibration results.