基于网络的无人机实时仿真系统软件

提出一种基于C/S结构的UDP网络便携式无人机半实物实时仿真系统,设计了嵌入式实时仿真软件、仿真控制与显示软件、网络通信软件.在由飞行控制计算机实物、电动舵回路实物和实时仿真设备组成的无人机半实物实时仿真试验环境下,对所设计的仿真系统软件进行全过程实时飞行仿真试验验证.验证结果表明,所设计软件功能正确,性能满足设计指标.     

Boost-Flyback单级PFC变换器

设计Boost-Flyback单级功率因数校正(Power factor correction,PFC)变换器主要应着眼于两点:一是功率因数(Power factor,PF)值要求;二是直流母线电压.为了给设计提供依据,本文详细推导了其功率因数及储能电容电压表达式,分析了它们与电路参数的关系,定量地给出变换器达到所需PF值的条件,指出当后IFlyback工作在电流断续模式(Discontinuous current mode.DCM)时,储能电容电压不随负载变轻而上升,避免了功率器件电压应力过高的问题.最后设计了PF>0.9的原理样机,通过实验验证了分析的正确性.     

麦秸纤维/聚丙烯复合材料

为了充分利用农业剩余物资源、降低材料的成本,本文将麦秸纤维与聚丙烯复合制备绿色环保型材料,研究了硅烷偶联剂种类、麦秸纤维含量以及相容剂MAPP含量对材料力学性能的影响,采用扫描电镜、体视显微镜观察麦秸纤维的分散性以及材料的冲击断口形貌.结果表明:KH550或A151表面处理明显降低了麦秸纤维的极性,改善其与聚丙烯的相容性,提高了材料的力学性能;当麦秸纤维质量分数为25%左右时,在聚丙烯基体保持均匀分散,增强效果最佳;当MAPP质量分数为8%左右时,材料的拉伸、弯曲以及冲击强度均达到最大值.     

基于实时SSR数据的LEO卫星精密单点定位研究

对目前低轨卫星实时定位的方法进行了研究,现在通常采用GPS定位,使用广播星历和普通晶振,实时定位精度一般在10m以内,不能满足高精度实时定位的需求。IGS组织在全球范围内对GPS跟踪分析,生成精密星历、精密钟差产品、按SSR格式的广播星历和钟差修正产品并在网上发布。对这些IGS产品进行了调查,提出在现有测控支持情况下,可以通过高密度上注SSR信息流实现在轨高精度定位。以某型号低轨微小卫星在轨导航增强载荷为应用背景,用IGS03产品中的1057和1058数据对双频GPS接收机的星历和钟差进行修正,采用递推最小二乘估计和LAMDA模糊度固定过对载波相位和伪距信息进行处理,在短时间内获得亚米级定位结果。     

亚轨道飞行器航程控制的末端能量管理方法

提出一种针对小能量亚轨道飞行器在无动力返回末端区域的多参数耦合、能量航向分离控制、动势能匹配衰减的精确控制的末端能量管理方法。以动能、势能作为约束条件,以航程作为优化指标,采用能量控制方法实时生成能量剖面,根据飞行器名义能量/航程在能量剖面中的位置确定迎角,最终生成三个姿态角。仿真结果表明用这种方法得到了良好的制导结果。     

平流层飞艇太阳能源系统研究

以平流层太阳能飞艇平台为背景,对平流层太阳能飞艇能源系统展开了分析和研究。文中建立了飞艇表面太阳能电池接收太阳直接辐射、散射辐射、反射辐射的模型。利用该模型对某飞艇太阳能电池进行计算,结果显示飞艇接收的太阳辐射能量与飞艇的工作纬度、季节、太阳能电池阵列表面面积、飞行姿态密切相关。当飞艇的脊背从日出到日落时刻正对太阳光线时,太阳能电池接收到的太阳辐射能量将是最大的。     

Adaptive Nonlinear Optimal Compensation Control for Electro-hydraulic Load Simulator

 Directing to the strong position coupling problem of electro-hydraulic load simulator (EHLS), this article presents an adap-tive nonlinear optimal compensation control strategy based on two estimated nonlinear parameters, viz. the flow gain coeffi-cient of servo valve and total factors of flow-pressure coefficient. Taking trace error of torque control system to zero as control object, this article designs the adaptive nonlinear optimal compensation control strategy, which regards torque control output of closed-loop controller converging to zero as the control target, to optimize torque tracking performance. Electro-hydraulic load simulator is a typical case of the torque system which is strongly coupled with a hydraulic positioning system. This article firstly builds and analyzes the mathematical models of hydraulic torque and positioning system, then designs an adaptive nonlinear optimal compensation controller, proves the validity of parameters estimation, and shows the comparison data among three control structures with various typical operating conditions, including proportion-integral-derivative (PID) controller only, the velocity synchronizing controller plus PID controller and the proposed adaptive nonlinear optimal compensation controller plus PID controller. Experimental results show that systems’ nonlinear parameters are estimated exactly using the proposed method, and the trace accuracy of the torque system is greatly enhanced by adaptive nonlinear optimal compensation control, and the torque servo system capability against sudden disturbance can be greatly improved.     

激光焊接ZL114A/5A06 异种铝合金接头组织及性能

采用激光焊接ZL114A/5A06异种铝合金,通过参数优化以获得性能优良的焊接接头,利用光学显微镜(OM)、拉力试验机、高温疲劳试验机、SEM和EDS对接头的显微组织、力学性能和拉伸断口进行了研究。结果表明:焊缝中心区的金相组织为等轴晶;接头焊后不经热处理,抗拉强度可达到265 MPa,为母材强度的80%以上,并有很好的抗疲劳性能;断口分析显示断裂位置在ZL114A母材一侧的熔合线附近;在保证焊透的前提下,激光功率越小,晶粒越细小,接头强度越高。对框架蒙皮结构铝合金贮箱产品试验件进行了焊接,试验件达到了产品各项性能指标要求。     

TLE数据误差与基于TLE数据的交会预报分析

目前普遍使用TLE数据进行在轨物体的危险交会预报. TLE数据误差不仅会影响交会预报的准确性, 还是计算碰撞概率的必要参数, 因此, 只有准确估计TLE数据误差, 才能得到可信的碰撞概率数值. 本文采用两种方法, 即TLE数据自比和与高精度轨道预报数据相比较的方法, 计算TLE数据误差, 并分别利用TLE数据和高精度数据计算同一交会, 比较两种数据预报的交会结果差异. 结果表明, 采用TLE根数自比方法的计算误差偏小, 而使用精轨数据作为校准数据所得到的TLE误差更接近真实误差, 计算碰撞概率更为合理, 有利于减少虚警.      

Design of an innovative multi-stage forming process for a complex aeronautical thin-walled part with very small radii

In this paper, an aeronautical thin-walled part with a complex geometry which has several sharp bends and curvatures in different directions was investigated. This kind of part is difficult to be manufactured only in one stage. Therefore, an innovative multi-stage active hydroforming process assisted by the rigid forming method was designed. In addition, an optimized blank geometry is obtained. In fact, the main focused point of this paper is to propose a new small radius rounded corner forming technique and analyze the mechanism. Two kinds of forming modes of changing a big rounded corner into a small one, which are related to different tangential positions of the die in the process of calibration, are analyzed theoretically. Meanwhile, the stress and strain states of the deformation region are compared. The relationships between the minimum relative radii of rounded corners I and II in the first stage and the hydraulic pressure are calculated by the bending theory. Finally, the influences of the tensile-bulging effect and the interface condition of the double-layer sheet on the forming quality of the specimen are investigated. The achieved results can make a foundation for utilizing the proposed method in forming of thin-walled parts with very small radii.