EGI/IMU integration using multiple IMUs and error damping loop for SAR motion compensation

We propose an EGI/IMU integrated smoothing algorithm based on extended Kalman filter (EKF) for synthetic aperture radar (SAR) motion compensation. Conventional navigation algorithms have discontinuities intrinsically which are caused by the measurement update done by the Kalman filter. The discontinuities are as harmful to the SAR image quality significantly as the relative position error. In order to eliminate discontinuities and to reduce relative position error, an additional inertial measurement unit (IMU) is used with master embedded GNSS inertial navigation system (EGI). The additional IMU contributes to smoother output and navigation accuracy. The error correction by EKF is performed gradually between measurement updates, which significantly improves the smoothing performance. Through Monte-Carlo simulation, the performance improvements in relative accuracy and continuity are confirmed.