基于永久散射体合成孔径雷达干涉测量技术的地面沉降监测

城市施工建设及地下水开采活动日益频繁，导致城市地面沉降问题日益严重。虽然传统地面沉降监测技术的精度较高，但成本也高。近年来，星载合成孔径雷达干涉测量(InSAR)技术发展起来，已被用于监测大范围地表形变，具有低成本、大面积、高精度等特点。首次采用永久散射体合成孔径雷达干涉测量(PSInSAR)技术，监测上海西南某区域2017—2021年间的地面沉降。结果显示:除一处楼房外，该区域大部分地区未发生沉降，最大沉降速率约-7.10 mm/a，最大沉降量约25.43 mm。采用该技术监测沉降，一方面节省了大量的人力和物力;另一方面，本研究成果对城市地表沉降的科学防治具有重要的参考意义。     

分布式飞行器测控数据实时解析系统设计研究

传统飞行器测控数据解析系统无法同时满足数据解析的实时性和完整性要求。针对此问题,研究了一种分布式飞行器测控数据实时解析系统,分布式系统由多个处理机耦合,具有资源共享、高可靠性,可进行高速并行计算等优点,满足了数据解析的实时性和完整性的要求,并通过了试验验证。     

Periodic event-triggered formation control for multi-UAV systems with collision avoidance

In this paper, periodic event-triggered formation control problems with collision avoidance are studied for leader–follower multiple Unmanned Aerial Vehicles (UAVs). Firstly, based on the Artificial Potential Field (APF) method, a novel sliding manifold is proposed for controller design, which can solve the problem of collision avoidance. Then, the event-triggered strategy is applied to the distributed formation control of multi-UAV systems, where the evaluation of the event condition is continuous. In addition, the exclusion of Zeno behavior can be guaranteed by the inter-event time between two successive trigger events have a positive lower bound. Next, a periodic event-triggered mechanism is developed for formation control based on the continuous event-triggered mechanism. The periodic trigger mechanism does not need additional hardware circuits and sophisticated sensors, which can reduce the control cost. The stability of the control system is proved by the Lyapunov function method. Finally, some numerical simulations are presented to illustrate the effectiveness of the proposed control protocol.     

星载高增益毫米波SAR相控天线阵设计

介绍了一种高增益、高效率的星载毫米波合成孔径雷达(SAR)有源相控天线阵的设计。天线单元采用了窄边开缝的波导缝隙天线，辐射缝隙与波导宽边垂直，天线具有效率高、匹配良好的特点。在方位向，波导缝隙天线组成直线阵，直线阵内采用折叠的波导功分器降低了直线阵的剖面高度。在距离向，波导缝隙直线阵紧密排布，形成一维相扫阵列。定标网络及馈电网络均采用波导形式并集成于天线阵列背面，其中，定标网络通过定向耦合器改善了定标通道的一致性及带内起伏特性，馈电网络通过魔T结构改善各有源通道间的隔离度。以距离向84个直线阵为一个子阵列，最终设计的天线全阵在方位向共包含8个子阵列，总体尺寸是595.8λ0×56λ0(λ0是中心频率在自由空间中的波长)。实测天线带内最高增益为54.37 dBi，辐射效率65.2%。天线阵列具有高增益、高效率的优点，同时结构简洁紧凑，适用于星载毫米波SAR系统。     

Experimental research on aero-propulsion coupling characteristics of a distributed electric propulsion aircraft

Distributed Electric Propulsion (DEP) aircraft use multiple electric motors to drive the propulsors, which gives potential benefits to aerodynamic-propulsion interaction. To investigate and quantify the aerodynamic-propulsion interaction effect of the wing section, we built a DEP demonstrator with 24 “high-lift” Electric Ducted Fans (EDFs) distributed along the wing’s trailing edge. This paper explores and compares the aero-propulsion coupling characteristics under various upstream speed, throttle, and EDF mounting surface deflection angles using a series of wind tunnel tests. We compare various lift-augmentation power conditions to the clean configuration without propulsion unit under the experiment condition of 15–25 m/s freestream flow and angles of attack from ?4° to 16°. The comparison of computational results to the experimental results verifies the effectiveness of the computational fluid dynamic analysis method and the modeling method for the DEP configuration. The results show that the EDFs can produce significant lift increment and drag reduction simultaneously, which is accordant with the potential benefit of Boundary Layer Ingestion (BLI) at low airspeed.     

基于自适应通信拓扑的无人机集群弱路径约束下的分布式控制器设计

针对传统无人机集群飞行控制需要规划过多飞行路径的问题，设计一种结合线性二次型调节器(LQR)与机间防撞的分布式协同控制器，不需要为集群设计相对构型，只需给定一条满足无人机动力学约束的飞行路径，集群就可沿路径飞行。该控制器通过设计自适应通信拓扑来稳定加入机间防撞机制带来的抖振效应，并使集群具有良好可扩展性。仿真结果表明，所设计的分布式控制器可以实现规划一条路径下无人机集群无机间碰撞的稳定飞行。     

Distributed fixed-time attitude coordinated control for multiple spacecraft with actuator saturation

This paper investigates the distributed fixed-time attitude coordinated control problem for multiple spacecraft subject to actuator saturation under the directed topology. First, a distributed fixed-time observer is presented for each follower spacecraft to estimate the leader spacecraft’s states. Compared with the commonly used fixed-time observer, the settling time of the proposed fixed-time observer can be easily adjusted by some free design parameters. Next, a distributed fixed-time control ...     

敏捷SAR卫星平台载荷一体化控制方法研究

面向具备波束指向捷变能力的小型化敏捷合成孔径雷达(SAR)卫星成像需求,提出了通过平台姿态敏捷机动和载荷波束捷变扫描一体化控制实现条带成像、多条带拼接成像、滑动聚束成像等传统成像模式的方法。针对配合成像过程提出的大角度机动和高精度高稳定度连续指向跟踪控制要求,采用5个单框架控制力矩陀螺(SGCMG)组成的"五面锥"构形控制力矩陀螺群作为执行机构,设计了基于姿态四元数和角速度反馈的改进型递阶饱和控制器,实现了平台的敏捷机动和对目标的稳定跟踪指向。数学仿真结果表明:该控制系统有效可行。     

一种Ka波段多通道FMCW SAR数字接收机设计与实现

调频连续波体制合成孔径雷达(FMCW SAR)因其体积小、成本低、重量轻及分辨率高的优点越来越受到关注。随着软件无线电技术的迅速发展，数字信号处理机在SAR载荷系统中扮演越来越重要的角色。提出一种多通道Ka波段毫米波SAR数字接收机的设计与实现方法，详细分析了FMCW SAR去调频接收过程，研制出一种基于FPGA的多通道数字接收机平台。以三通道为例，采用多类滤波器级联技术，设计系统软硬件，最后通过系统测试及试验验证了方案的正确性与可行性。     

Adaptive event-triggered distributed optimal guidance design via adaptive dynamic programming

In this paper, the multi-missile cooperative guidance system is formulated as a general nonlinear multi-agent system. To save the limited communication resources, an adaptive eventtriggered optimal guidance law is proposed by designing a synchronization-error-driven triggering condition, which brings together the consensus control with Adaptive Dynamic Programming(ADP) technique. Then, the developed event-triggered distributed control law can be employed by finding an approximate solution of eve...