Two-position initial alignment method for redundant rotating inertial navigation system

Redundant Rotating Inertial Navigation System (RRINS) can further improve the reliability of the system on the basis of traditional rotating inertial navigation system. Aiming at the high-precision initial alignment requirements of this type of system, A two-position initial alignment method was studied by taking the regular tetrahedral redundant rotating inertial navigation system as an example. Firstly, every three gyroscopes and three accelerometers constituted a combination. The zero bias correlation and redundancy configuration of the inertial device under each combination were established. And the RRINS two-position stop scheme was designed to estimate the zero bias of the corresponding inertial device. But in some special cases, the observation position needs to be increased. Then, the results obtained by each inertial device under different combinations were averaged, and the average value was used to compensate the measurement information of the corresponding inertial device. Finally, based on the compensated inertial device output performs the initial alignment of the RRINS. Mathematical simulation and experimental verification results show that the method can effectively estimate the zero bias of the inertial device under different two-position schemes. In the simulation, the bias estimation error of the gyroscope is within 4%, and the bias estimation error of the accelerometer is basically within 2%. Compared with the case without bias compensation, the initial alignment accuracy is improved by more than 10 times. In the experiment, the initial alignment accuracy in both horizontal and azimuth directions was improved, and the heading angle alignment error was reduced by about 100 times. At the same time, the method can also be extended to redundant rotating inertial navigation systems with other configuration schemes, which has certain reference significance for improving the initial alignment accuracy of such inertial navigation systems.