LAUSR

A rotational inertial navigation system (RINS) can enhance the navigation accuracy by modulating the constant inertial device biases with gimbals rotation. To further improve the navigation performance in marine applications, two or more RINSs are usually equipped in the same vessel to achieve the information fusion. However, the lever-arm effect caused by the outer and inner lever-arm errors of two RINSs would decrease the fusion accuracy of velocity and position information. To solve this problem, the asynchronous gimbal-rotation-based calibration method for the outer and inner lever-arm errors of two RINSs is proposed in this paper. The lever-arm error and navigation error models were seriously deduced. Based on system models, the design principles of rotation schemes of two RINSs were analyzed and summarized. The calibration filter with the velocity difference of two RINSs as the mere measurement was constructed. The multiple asynchronous rotation schemes according to the design principles were tested and compared as well as optimized by simulations and experiments. The results indicated that the outer and inner lever-arm errors could be well calibrated and the calibration accuracy could be improved with the optimal rotation schemes. The velocity differences of two RINSs could be significantly restrained, and the fusion accuracy of linear motion information could be obviously improved after the compensation of lever-arm errors, which demonstrated the effectiveness of the proposed calibration method.