Trajectory Optimization for Maneuvering Platform Bistatic SAR With Geosynchronous Illuminator

Geosynchronous synthetic aperture radar (GEO-SAR) can provide long-duration and wide beam coverage over the interested target scene, which is an ideal illuminator for bistatic SAR acquisitions. As a particular system configuration, the GEO bistatic SAR with a maneuvering platform as the receiver (GEO-MP-BiSAR) can achieve continuous observation of the interested target during the flight. The target recognition and tracking information can be generated from the updating images for enhanced guidance performance. However, the bistatic SAR imaging performance is dependent on the observation geometry, which, in turn, is determined by the trajectory of the receiver. Therefore, in this article, the trajectory optimization for GEO-MP-BiSAR is first investigated. The goal of the method is to generate a set of feasible trajectories to guide the maneuvering platform toward the target, and meanwhile obtain the optimized imaging performance during the whole flight. The trajectory optimization is then modeled as a multiobjective optimization problem with multiple constraints, where the trajectory control and SAR imaging performance are comprehensively considered. Then, a knee-guided multiobjective evolutionary algorithm (KG-MOEA) is put forward to effectively solve the problem, where the knee solutions are utilized to guide the search process and improves convergence and diversity of the method. The proposed algorithm can generate the prescribed number of solutions with significant trade-offs between the performance metrics. The mission designer can then choose a solution from only a few optimized candidates for implementation, which greatly improves the efficiency of decision making. Experimental studies demonstrate the effectiveness of the proposed method.