对地聚束成像SAR卫星姿态控制技术研究

Research on Attitude Control Technology for SAR Satellite on Plotlight Mode

根据合成孔径雷达(SAR)卫星对地聚束成像模式下的任务特点,对其成像覆盖区域进行分析,推导出对地聚束成像的期望姿态跟踪规律。为了尽快跟踪地面目标,需要多轴同时进行大角度姿态机动控制;为了实现SAR天线对地聚束成像,跟踪上目标后还需要进行连续跟踪姿态机动。本文采用测速反馈的反作用飞轮控制技术,设计了基于时间最优bang-bang控制的PD控制器,实现了地面目标的快速跟踪指向;针对系统存在的扰动,在PD控制器中设计了系统的前馈输入补偿器,从而保证了姿态跟踪指向的精度。姿态控制系统数学仿真结果表明该控制技术有效。

SAR satellite has to embark on attitude maneuvers to make its SAR track and point at ground targets within a specitied span time in the spotlight mode. The large angle attitude maneuvers and tracking in the spotlight mode was studied in this paper. When the satellite relative attitude to the target is obtained,in order to track the groud target as soon as possible,SAR satellite must make large angle attitude tracking maneuver in two or three axes. The coverage area of plotlight SAR satellite was analyzed. According to the requirement of the assignment,the desired satellite reference attitude in the plotlight mode,angular velocity and angular acceleration strategy to track the groud target were designed. A PD control law based on bang-bang time optimal control was also designed. A front back compensater was imported to assure the precision of the control system. At last,a numerial example was provided to demonstrate the effectiveness of the proposed theoretical results.