基于编队控制的自适应HELLO更新算法

在无人机(UAVs)编队自组织网络中,针对无人机之间位置信息更新周期不合理,从而导致编队控制不稳定和控制开销过大的问题,提出一种基于无人机编队控制的自适应HELLO更新算法。该算法应用编队控制稳定性理论推导出无人机组成期望编队的控制延时上限,结合该延时上限和编队运动状态自适应地设定HELLO更新周期。仿真结果表明,本文提出的算法与固定HELLO更新周期算法相比,既能保证在组编控制过程的稳定性,又能实时维护稳定阶段的链路,并且显著减少网络中不必要的控制开销。      

GNSS single frequency ionospheric range delay corrections: NeQuick data ingestion technique

A study of the performance of the NeQuick model and the Klobuchar model for GNSS single frequency range delay correction on a global scale was done using data for moderate solar activity. In this study NeQuick was used in the way intended for Galileo. This study is to assess the performance of the two models at each ionospheric geographic region during moderate solar activity as previously published studies were concentrated only on high solar activity. The results obtained showed that NeQuick outperformed Klobuchar for the whole year at the three geographical regions of the ionosphere. In terms of monthly root mean square of mismodeling, NeQuick outperformed Klobuchar by 15 TECU or more at low-latitudes, 5 TEC or more at mid-latitudes, and 1 TECU or more at high-latitudes.     

脉冲激光测距误差标定及不确定度分析CSCD

以脉冲激光测距机的测距误差标定为背景,通过对测距误差解析表达式的推导,给出了系统各不确定度分量对测距误差的影响,计算了信号延迟时间、探测器和激光二极管响应时间、晶振频率、大气折射率等不确定度分量。通过对某已标定激光测距机实验验证表明:该装置在500m^20 000m测距范围内,测量重复性引入的相对标准不确定度最大值为0.67m,满足该类激光测距机测量不确定度5m(k=2)的校准测试需求。因此,利用该解析表达式可以实现对脉冲激光测距误差的有效评估,这对于脉冲激光测距测试系统、脉冲激光测距机的设计具有重要的指导意义。     

时隙分配算法在CDM GDP 程序中的应用

机场容量由于恶劣天气等突发原因受到限制导致大面积航班的延误,带来了巨大的经济损失.CDM(Collaborative Decision Making) GDP(Ground Delay Procedure)就是解决这类突发情况的空中交通流量管理程序.就其核心问题——时隙分配,在现有的时隙分配算法基础上,引入航班延误损失系数,使得算法以延误损失替代延误时间,提出了2种基于该系数的时隙分配算法.最后,用java语言进行了仿真实验,引入了评判函数来选择在总延误损失和延误损失分配的公平性上最佳满足决策者要求的分配结果.      

一种新型双轴太阳帆板驱动线路盒设计

针对双轴太阳帆板驱动装置2个电机的控制要求,提出一种新型双轴帆板驱动线路盒（BSADE,biaxial solar array drive electronics）设计.该线路盒基于现有帆板驱动线路设计,通过在电机驱动线路中设计一种电流方向转换延时线路,解决了电流方向转换瞬间功率管容易对穿的问题,确保了驱动线路工作的安全性,使得原先大功率管才能实现的线路选用小功率管实现,达到了小型化目标.通过对电机驱动线路和负载绕组进行交叉重组设计,解决了主备份线路间磁耦合问题,实现了严格冷备份目标,大大提高了可靠性.     

Tropospheric wet refractivity tomography using multiplicative algebraic reconstruction technique

Algebraic reconstruction techniques (ART) have been successfully used to reconstruct the total electron content (TEC) of the ionosphere and in recent years be tentatively used in tropospheric wet refractivity and water vapor tomography in the ground-based GNSS technology. The previous research on ART used in tropospheric water vapor tomography focused on the convergence and relaxation parameters for various algebraic reconstruction techniques and rarely discussed the impact of Gaussian constraints and initial field on the iteration results. The existing accuracy evaluation parameters calculated from slant wet delay can only evaluate the resultant precision of the voxels penetrated by slant paths and cannot evaluate that of the voxels not penetrated by any slant path. The paper proposes two new statistical parameters Bias and RMS, calculated from wet refractivity of the total voxels, to improve the deficiencies of existing evaluation parameters and then discusses the effect of the Gaussian constraints and initial field on the convergence and tomography results in multiplicative algebraic reconstruction technique (MART) to reconstruct the 4D tropospheric wet refractivity field using simulation method.     

时间触发AFDX网络的设计和实时性分析

时间触发机制可以近一步提高航空电子全双工交换式以太网(AFDX,Avionics Full Duplex Switched Ethernet)的确定性,保障时间关键消息具有完全的时间确定性.将时间触发机制引入了AFDX网络,设计了时间触发ADFX网络(TTAFDX,Time-Triggered AFDX)的体系结构,包括协议栈、虚拟链路类型、端系统调度、交换机调度、透明通信机制和降级通信机制,并且设计了端系统和交换机的时刻调度算法.对TTAFDX网络从理论和仿真实验两方面进行了分析,验证了TTAFDX网络对时间关键消息的完全时间确定性的保障.     

北斗系统UERE及定位精度评估

用户测距误差（URE）与用户设备误差（UEE）是影响定位精度的主要因素.民航是北斗系统的高端用户,监测其对民航机场的覆盖性和服务性能十分必要.本文根据华东、华南、华北、西北地区4个民航机场观测站的北斗实测数据,分析了各机场卫星的可见性.根据URE的解算方法、电离层修正模型、对流层修正模型以及定位精度的评估方法,给出了对应的性能评估结果.研究发现：可见星数均在6～14颗,满足定位要求; 95%置信度下,电离层延迟优于7.50m,对流层延迟优于13.28m,地球静止轨道卫星（GEO）、倾斜地球同步轨道卫星（IGSO）、中圆轨道卫星（MEO）卫星的URE值分别优于2.36m,1.72m,2.59m,满足北斗规范的要求;95%置信度下,定位精度水平方向优于3.63m,垂直方向优于6.98m.结果表明北斗系统在民航机场监测站的覆盖性及服务性能良好.     

45°(N)纬度带的Klobuchar like电离层延迟季节修正模型与评估

电离层延迟是全球卫星导航系统（GNSS）的主要误差源之一。对于装配GNSS单频接收机的航空器,选择简单有效的Klobuchar广播电离层模型来改正电离层延迟误差,其修正率为50%～60%。针对45°（N）纬度带,提出了更高电离层修正需求。考虑到季节因素对中高纬度地区电离层的显著影响,利用GIMs（Global Ionospheric Maps）分析了昼夜中TEC（Total Electron Content）的峰值和谷值随季节（年积日）的变化,建立了一种适用于45°（N）纬度带的Klobuchar like电离层模型。该模型不增加广播模型系数,新模型的夜间和VTEC高峰时电离层修正率分别达到了82%和80%,表明在穿刺点集中的45°(N)纬度地区使用该模型可以更精确地描述该地区的电离层,帮助航空器实现更高精度的定位。     

Performance evaluation of IRI-2007 at equatorial latitudes and its Matlab version for GNSS applications

International Reference Ionosphere (IRI) model is the widely used empirical model for ionospheric predictions, especially TEC which is an important parameter for radio navigation and communication. The Fortran based IRI-2007 does not support real-time interactive visualization and debugging. Therefore, the source code is converted into Matlab and is validated for the purposes of this study. This facilitates easy representation of results and for near real-time implementation of IRI in the applications including spacecraft launching, now casting, pseudolite based navigation systems etc. In addition, the vertical delay results over the equatorial region derived from IRI and GPS data of three IGS stations namely Libreville (Garbon, Africa), Brasilia (Brazil, South America) and Hyderabad (India, Asia) are compared. As the IRI model does not account for plasmasphere TEC, the vertical delays are underestimated compared to vertical delays of GPS signals. Therefore, the model should be modified accordingly for precise TEC estimation.