Research on Improving Heading and Attitudes Accuracy by Online Calibration of Errors Based on Multi-RINSs Joint Rotation Modulation

The ship usually adopts multiple sets of rotational modulation inertial navigation system (RINS) to ensure the accuracy and reliability of long endurance navigation, but the rotational modulation will excite the gyro installation error and scale factor error, which will cause periodic oscillation of navigation attitude information, moreover, due to the influence of temperature, vibration and other environments, these errors will change in the results of pre-calibration, and it is impossible to accurately model them, resulting in the further aggravation of attitudes oscillation, which is not conducive to the transfer alignment between master and slave INS. However, the ship is always swinging or maneuvering, a single RINS can not complete self-calibration independently in dynamic condition. In order to solve the above problems, in this paper, an online calibration algorithm based on joint rotation modulation of multi-RINSs is proposed for redundant configuration of multi-RINSs without extra conditions, and the error parameters are tracked and estimated every 4 minutes, the dynamic simulation results show that the calibration strategy can effectively calibrate the gyro installation error, the nonorthogonal angle between the gimbals and the scale factor error of the z-gyro of each RINS, which proves the correctness of the calibration strategy. The results of 3h navigation experiment show that the amplitude of attitudes oscillation decreases about 80% after the compensation of joint calibration error parameters, the fluctuation amplitude of heading angle decreases by 70%, the effectiveness of the calibration strategy in practical application is further verified, the relationship of ship multi-RINSs changes from backup to assistance, which is of great significance to improve the heading and attitudes accuracy of RINSs and the transfer alignment performance between master and slave INS.