【作者】 李勃；

【导师】 谢求成；

【作者基本信息】 南京航空航天大学 ， 信号与信息处理， 2009， 博士

【摘要】 由于无人机对机载设备体积、重量、功耗的限制,使许多电磁兼容性设计方案都无法实施,而且并没有现存的标准和设计规范可以参考。在此背景下,承担了某“十五”科学技术预先研究项目,其中一部分就是无人机电磁兼容专家系统软件平台的研究。根据无人机电磁兼容性的特点,对该专家系统中几个具有重要意义的关键问题进行了分析。首先,分析了国军标GJB151A、GJB152A所提出的理论依据,这也是一切无人机电磁兼容设计的出发点。充分理解国军标中各项指标的意义和极限值的合理性,有利于对国军标进行合理的剪裁和应用。其次,提出了一种新的设备级电磁兼容测试法――六基组测试法。这一新的测试法方法可以极大地节省设备级电磁兼容测试的时间和费用。分析了实际电磁环境对无人机的影响,通过在实际飞行环境中对各地面发射机的辐射和场地电磁环境的测试,得到对无人机造成伤害的电磁环境场强极限值在0.1～8×10~3MHz频段中为60～200V/m。将不同频段下传导干扰与辐射干扰进行结合分析,并根据无人机中存在的辐射干扰和传导干扰的共性特征,得到无人机系统级电磁辐射极限场强在0.1～2×10~3MHz频段中为60dBμV/m~100dBμV/m。该指标的制定为无人机系统的电磁兼容设计提供了一个有效的评估准则。并由此提出了无人机系统级电磁兼容测试法。基于偶极子的相关性运算法则,计算得出了在不同测试场地中辐射发射测试结果的相关系数,该系数对于提高无人机电磁兼容测试的精度有极大的帮助。根据各种电磁兼容设计手册和多位无人机设计专家的经验,总结出了各种有效的无人机电磁兼容设计方法。在设计初期就采用这些方法,可以有效地降低电磁干扰,提高系统的电磁兼容性,明显的缩短设计周期和减少设计经费。然后,根据无人机电磁兼容专家系统的要求,提出了几种新颖有效的计算方法,可以对无人机电磁兼容设计的各个方面进行准确的分析和预测。⑴提出了机载天线——天线之间电磁干扰分析的数学模型,该模型的计算误差在通常使用的范围内小于2%。⑵提出了对复杂电路结构的布线间距的计算方法,该方法的误差在取值很大的情况下也不会超过9%。⑶采用分布元素法的原理,提出了一种新的预测电路板辐射的方法,它的计算结果和实际测试结果十分相近,证明了该计算方法是比较准确的。⑷提出了一种基于非标准曲线算子的三维高阶FDTD算法,用于解决复杂介质结构的电磁兼容性问题。通过计算结果可以看出,高阶非标准FDTD算法的准确度极高,而且没有任何色散情况出现,并且高阶非标准FDTD算法还可以节省大约85%的CPU和内存使用。最后,提出了无人机系统级电磁兼容专家系统的设想,它力图模拟电磁兼容专家的思考过程而且不需要使用者具有丰富的设计经验。由于专家系统的复杂性,只是给出了该专家系统的基本结构及一些关键问题的解决方法和主要的计算方法。更多还原

【Abstract】 Many electromagnetic compatibility (EMC) design methods cannot be applied on unmanned aerial vehicle (UAV) for volume, weight and power restrictions of airborne equipments. And there is no existing standard or design criterion of UAV to follow. Therefore, the EMC pre-research task of UAV was advanced, which included research on EMC expert system of UAV. Based on characteristics of EMC of UAV, author analyses several important problems in EMC expert system of UAV.Firstly,the theory foundation of national military standard is analyzed, which is the basis of whole EMC design of UAV. It is propitious to national military standard tailoring and application by fully understanding the meaning and rationality of each item and limit in national military standard.Then, a novel sub-system EMC test method-rule of six test method was raised. This new method can save a lot of testing time and expenses.The real electromagnetic (EM) environment effects on unmanned aerial vehicle is analyzed. And the max harmful outside word EM environment level to UAV is gained after many electromagnetic compatibility tests in darkroom and in actual flying field, which is 60-200V/m in 0.1-8×103MHz bandwidth. The EMC standard at the system level of UAV is advanced as 160dBμV/m-100dBμV/m in 0.1-2×103MHz bandwidth after analyzing the combined effects of conducted and radiated interferences based on the common EM radiated and conducted characteristics of UAV. The standard can provide an effective evacuating rule for EMC of UAV.According to the dipole model, the correlation coefficients of different testing conditions were calculated. The coefficients will help to improve the precision of EMC test.Based on EMC design manual and experiences from UAV experts, many effective EMC design method of UAV were summarized. Adopting these methods at the beginning of design can reduce radiation, enhance EMC of system, shorten design period and cut down design outlays. Subsequently, based on the requirement of EMC expert system of UAV, several novel and effective algorithmic methods were proposed. These methods can help designers to analyze and prognosticate various aspects of EMC design of UAV.(1)The mathematics model of EM interference between airborne antennas was established. The error of this model is normally less than 2%.(2)A calculation method of distance between lines of complicated circuit structure was put forward. The error of this method will not exceed 9% even at large values.(3)Based on distribution method, a novel method to predict the radiation of printed circuit board(PCB) was present. The calculation result is very close to the real test result, which proves the accuracy of this method.(4)A higher order finite-difference time-domain (FDTD) algorithm based on which based on non-standard curvilinear operator was introduce to resolve EMC problems in complex material structure. It can be seen from the calculation results this higher order FDTD method highly improves accuracy and significantly suppresses the artificial dispersion errors. And this method can also save 85% consumption of central processing unit (CPU) and memories approximately.Finally, the perspective of EMC expert system of UAV is proposed. The expert system is trying to simulate the thinking process of real EMC experts without requirements for abundant experiences of designers. Only the basic structure and resolvents of some key problems are mentioned, along with several main algorithmic methods.更多还原