Relative Attitude Initial Alignment of Array POS Based on Relative Inertial Solving

Array position and orientation system (POS) is the key equipment to measure multipoint motion and relative motion for array synthetic aperture radar (SAR) high-precision 3-D imaging. Relative attitude initial alignment plays a great role in the motion measurement accuracy of the array POS. The existing alignment methods are very difficult to achieve high precision without prior latitude information. To solve this problem, a relative attitude initial alignment method of array POS based on relative inertial solving is proposed. First, the fast coarse alignment approach based on three orthogonal vectors is presented to obtain the initial relative attitude rapidly by only using gyroscope and accelerometer data. Second, the fine alignment model based on relative inertial solving is established to gain the high-precision relative attitude on the basis of the coarse alignment results. Finally, the experimental results show that the proposed two-stage alignment method, compared with the traditional method without latitude information, not only has a fast convergence speed and higher relative attitude estimation accuracy in the coarse alignment stage, but also further improves the performance in the fine alignment stage with the attitude accuracy increasing by more than 29.4%.