An Improved Initial Alignment Method for SINS/GPS Integration With Vectors Subtraction

SINS/GPS integrated navigation system has been used widely in many application situations. In the SINS/GPS integrated navigation system, the initial alignment process is carried out to determine the initial attitude of the vehicle. Based on the previous works, the position loci method is a robust initial alignment method. The outliers, which are contained in the GPS measurements, can be suppressed by the position loci. However, the initial velocity is used to construct the observation vectors in the previous works. When the errors are contained in the initial velocity measurements, the initial alignment results are bad. To address this problem, the vector subtraction operation is adopted in this paper. Then, the initial velocity is offset by this operation. Thus, the interferences, which are caused by the initial velocity errors, are suppressed. The simulation and field tests are designed to verify the performance of the proposed method. It can be found that the alignment results are similar with the methods, which contains small or no initial velocity error.