Research On The Location And Orientation For Vehicular Rotation Inertial Navigation System

The rotation modulation technique (RMT) is employed to depress the measurementerror of the inertial measurement unit (IMU), and to increase the performance of theinertial navigation system (INS). This dissertation mainly studies the RMT, in order todetermine the location and orientation accurately by applying the RMT to the vehicularINS. The following work has been completed in the thesis.1. Several rotation schemes for the depression of navigation error of vehicularrotation INS are investigated based on the RMT. The time-domain analyticalexpressions of navigation error with single-axis rotating are derived based on the errorpropagating model for the rotation INS. The principle of the RMT is analyzed comparedwith the static situation. The depression and the engineering applicability of differentrotation schemes are analyzed. Analysis and simulation results show that thesixteen-sequence scheme can completely compensate the constant errors, factor scaleerrors and misalignment errors of the inertial sensors, and this scheme can be used as apractical solution in the vehicular rotation INS.2. The effect of vehicle angular motions upon the RMT is analyzed. By analyzingthe projection of gyroscopic measurement error of rotation INS under the vehicleangular motion in navigation frame, the effect of vehicle angular motions is investigated.Analysis and simulation results show that the performance of the RMT is seriouslyaffected by the vehicle angular motions. In order to improve the navigation accuracy ofthe RMT in dynamic situation, the method of isolating the IMU from the head motion isproposed,3. The initial alignment for rotation INS is investigated. Because the IMU can berotated with the gimbals, the multi-position alignment can be processed for rotation INS.The observability of the system is analyzed and the optimal2-position alignment issimulated. The analysis results indicate that the “alignment-modification-alignment”method can be employed to guarantee the alignment precision when the accuracy ofoptimal2-position alignment cannot satisfy the navigation requirement.4. The navigation computation schemes of the vehicular rotation INS areinvestigated. The basic computation equations of different navigation computationschemes are obtained, and the error propagating models are developed. The effects ofthe angle measurement error and the rotation rate measurement error of the rotationplatform on the accuracy of the two different schemes are analyzed. The analysis resultsshow that the angle measurement error and the rotation rate measurement error affectthe navigation accuracy of the vehicle’s attitude, velocity and position, when usingdirect computation scheme. Contrastively, only the attitude accuracy is affected by theangle measurement error when using indirect scheme.