Research On Dynamic Alignment Based On FOG SINS/DVL Integrated Navigation System

Inertial navigation system is widely used in the military,aerospace,maritime and civil aviation navigation because of its autonomous quality,concealment.The initial alignment technology of navigation system has been one of the key technologies of inertial navigation systems,and the precision of inertial navigation system has a direct relationship with the alignment accuracy.The initial alignment error is the main error sources of inertial navigation systems.Considering the complexity of the actual ship work environment,it is significant to research on dynamic alignment techniques for shipboard high-precision SINS initial alignment.The paper make a detailed study of the SINS initial alignment and semi-physical simulation and verification,aiming at system in different methods of state static carrier,swing,mooring and uniform direct environmental.The paper beginning with the principle of inertial navigation systems,the system error equation that is derived can be used for later fine initial alignment process' state equation establishment.Second,analysis the speed measurement principle of Doppler Velocity Log(DVL),and then establish the Doppler Log speed error equation.As the output noise of inertial devices has direct effects on the accuracy of the initial alignments and considering noise characteristics,the paper designs the IIR filter and a Hidden Markov Model Kalman Filter(HMM-KF).And to improve the accuracy of the initial alignments,it pre-filters output noise of inertial devices.Thereafter,the systematic study of the SINS alignment methods from static base initial alignment,mooring alignment to the uniform direct alignment.The alignment on the stationary base uses analytic coarse alignments and Kalman filter fine alignments.The mooring alignment utilizes inertial frame coarse alignment and Kalman filter fine alignments.The uniform direct alignment requires velocity measurements from DVL and it also inertial frame coarse alignment and Kalman filter fine alignments.Finally,the article elaborates the alignment of SINS compass methods and maintains the principle diagram of road alignments.And by comparing it with the Kalman filter under the mentioned environment,the paper can achieve that SINS compass methods and Kalman filter fine alignments are effective and both of them can complete the higher accuracy initial alignments.In this paper,a comprehensive analysis of SINS initial alignment in different states is made.The paper extends the coarse alignment of inertial frame,whose mainly task is to estimate direction cosine matrix between the solidification inertial frame and the inertial frame.In addition to calculating using the matrix inversion multiplying,it can use the Wahba's problem based on attitude determination to achieve inertial frame coarse alignment.The alignment methods,such as TRIAD,singular value decomposition(SVD)and Q-method are demonstrated in details and emulator-validated in this paper.And it can be further found that singular value decomposition(SVD)and Q-method can also achieve precision alignment.