A novel alignment accuracy evaluation approach for shipborne slave INS

Transfer alignment is a moving base alignment method which has been widely used in shipborne low-accuracy inertial navigation system (INS). The accuracy of transfer alignment has mainly determined the entire navigation performance of low-accuracy INS and should be obtained. In this paper, transfer alignment accuracy evaluation methods for shipborne salve INS are analyzed. Observability analysis of evaluation system is implemented, and its validity on the illustration and prediction for the potential smoothing results are verified. The relationships between accelerated motion, rotation observation variable and the performance of evaluation approaches are obtained. Then, a novel transfer alignment accuracy evaluation approach is presented. The azimuth information provided by differential GPS (DGPS) is introduced together with the velocity and position provided by DPGS as the observation variables. Kalman filter and RTS smoother are applied to process these data. Simulations are conducted and the results show that this method exhibits excellent performance, and all the errors of smoothed estimations are less than 1 percent, especially with a better estimation result of the azimuth misalignment angle.