An Image-Quality-Constrained Approach to Initial Estimation and Compensation of Motion Errors in SAR Simultaneous Localization and Imaging Optimization Framework

Airborne Synthetic Aperture Radar (SAR) can be deployed at an elevated altitude to sense remotely and image intricate scenes on the ground. However, due to the influence of complex factors such as artificial and physical factors, flying platforms are often unable to detect in accordance with the preset flight trajectory, which requires the positioning of the moving platform itself. Existing radars typically employ satellite navigation and inertial guidance equipment for positioning purposes. However, the precision of the motion measurement equipment and the quality of the satellite navigation signal impose constraints on the cumulative positioning error and the absence of positioning information, respectively. The radar echo inherently encodes positional information between the platform and the scene. Taking into account the close relationship between the radar image quality and the radar's own positioning accuracy, this paper proposes an image-quality-driven simultaneous positioning and imaging method for SAR. Firstly, a generic airborne platform motion model and a radar measurement model are established, and the optimization is performed in two steps. The initial stage of the process entails the estimation of a coarse trajectory based on the echo history. The subsequent stage is driven by the image quality on the basis of the aforementioned trajectory. Ultimately, the trajectory information pertaining to the radar itself is estimated. Simultaneously, the imaging results of the scene can be obtained based on the estimated trajectory. The efficacy and reliability of the proposed method have been validated through simulations and real data experiments.