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一种精确的地球同步轨道SAR成像聚焦方法 被引量:6
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作者 胡程 刘志鹏 +2 位作者 曾涛 符蓓蓓 朱宇 《兵工学报》 EI CAS CSCD 北大核心 2010年第S2期28-32,共5页
地球同步轨道合成孔径雷达(GEO SAR)轨道高度大,因此合成孔径时间内可获取几百甚至上千公里的高分辨率合成孔径雷达图像,为宽区域内的目标侦察与精确打击提供了一种有效的技术手段。大的轨道高度给GEO SAR带来了很多的优点,但也给GEO SA... 地球同步轨道合成孔径雷达(GEO SAR)轨道高度大,因此合成孔径时间内可获取几百甚至上千公里的高分辨率合成孔径雷达图像,为宽区域内的目标侦察与精确打击提供了一种有效的技术手段。大的轨道高度给GEO SAR带来了很多的优点,但也给GEO SAR成像带来了很多难点。传统基于直线轨迹模型推导的低轨合成孔径雷达二次距离压缩算法在GEO SAR中应用将产生几百弧度的高阶相位误差,并导致严重的距离向空变性,从而使目标在长合成孔径时间和大场景下难以精确聚焦。本文主要对二次距离压缩(SRC)算法在GEO SAR近地点的情况进行了修正,基于精确的曲线轨迹模型解析的推导了方位向参考函数的调频斜率,并对方位向参考函数调频斜率的变化进行了自适应补偿,克服了大场景距离向的空变性。在100 s长合成孔径时间及40 km场景下,通过仿真验证了算法有效性,实现了GEO SAR的高精度成像。 展开更多
关键词 信息处理技术 GEO SAR 二次距离压缩算法 直线轨迹模型 菲涅尔近似
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Helicopter Maneuver Trajectory Tracking Control Based on Implicit Model and LADRC
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作者 REN Binwu CUI Zhuangzhuang +2 位作者 XU Yousong DU Siliang ZHAO Qijun 《Transactions of Nanjing University of Aeronautics and Astronautics》 CSCD 2024年第6期739-749,共11页
To enhance the stability of helicopter maneuvers during task execution,a composite trajectory tracking controller design based on the implicit model(IM)and linear active disturbance rejection control(LADRC)is proposed... To enhance the stability of helicopter maneuvers during task execution,a composite trajectory tracking controller design based on the implicit model(IM)and linear active disturbance rejection control(LADRC)is proposed.Initially,aerodynamic models of the main and tail rotor are created using the blade element theory and the uniform inflow assumption.Subsequently,a comprehensive flight dynamic model of the helicopter is established through fitting aerodynamic force fitting.Subsequently,for precise helicopter maneuvering,including the spiral,spiral up,and Ranversman maneuver,a regular trim is undertaken,followed by minor perturbation linearization at the trim point.Utilizing the linearized model,controllers are created for the IM attitude inner loop and LADRC position outer loop of the helicopter.Ultimately,a comparison is made between the maneuver trajectory tracking results of the IM‑LADRC and the conventional proportional-integral-derivative(PID)control method is performed.Experimental results demonstrate that utilizing the post-trim minor perturbation linearized model in combination with the IM‑LADRC method can achieve higher precision in tracking results,thus enhancing the accuracy of helicopter maneuver execution. 展开更多
关键词 HELICOPTER trajectory tracking implicit model(IM) proportional-integral-derivative(PID) linear active disturbance rejection control small disturbance linearization spiral up Ranversman maneuver
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