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研究旋翼无人机作为合成孔径雷达(Synthetic Aperture Radar,SAR)的移动平台,为了提高机动灵活性,但是同样也会带来剧烈的飞行扰动。通常借助于全球定位系统(Global Positioning System,GPS)实时获取雷达位置是常用的机载SAR运动补偿方法,但是GPS天线和雷达天线的安装位置在空间上并不重合,而二者之间的空间位置差被称为杠杆臂,杠杆臂的存在使得GPS测量结果并不能真实表征雷达天线位置,直接使用GPS测量结果将使得运动补偿出现偏差。提出的杠杆臂补偿方法,能够根据GPS测量结果实时解算雷达天线位置,从而使用更为准确的雷达运动参数补偿误差,获取高精度高质量的SAR图像。从旋翼无人机运动模型入手,分析了杠杆臂误差对成像的影响,并给出了依据GPS和姿态数据演算的雷达天线位置。最后,在仿真的基础上引入了实测的旋翼无人机的运动数据,验证了改进算法的有效性。
Research Rotorcraft UAVs are used as the mobile platform of Synthetic Aperture Radar (SAR). In order to improve maneuverability, however, it will also bring about severe flight disturbances. It is common practice to obtain the radar position by means of the Global Positioning System (GPS). However, the installation positions of the GPS antenna and the radar antenna do not coincide spatially, and the space between the two Position difference is called the lever arm, the presence of the lever arm makes the GPS measurement results do not truly characterize the radar antenna position, the direct use of GPS measurements will make the motion compensation bias. The proposed lever arm compensation method can calculate the position of the radar antenna in real time according to the GPS measurement results, so as to compensate the error with the more accurate radar motion parameters and obtain the SAR image with high precision and high quality. Based on the rotor UAV motion model, the influence of lever arm error on imaging is analyzed and the position of radar antenna based on GPS and attitude data is given. Finally, based on the simulation, the measured rotor UAV motion data are introduced to verify the effectiveness of the improved algorithm.