Maximal admissible mode decision delay in terminal guidance

Mode decision-maker is a critical component in the logic-based Integrated Estimation and Guidance(IEG) system. For the best possible estimation and guidance performance, the mode decision delay of the mode decision-maker should be limited to a range as small as possible. This paper presents a numerical method for computing the maximal admissible mode decision delay that varies with time-to-go. Particular attention has been paid to highly maneuvering target interception in terminal guidance. The results of this research offer useful guidelines for the design of the mode decision-maker in IEG systems.     

Modeling novel methodologies for unmanned aerial systems–Applications to the UAS-S4 Ehecatl and the UAS-S45 Bálaam

The rising demand for Unmanned Aerial Systems(UASs) to perform tasks in hostile environments has emphasized the need for their simulation models for the preliminary evaluations of their missions. The efficiency of the UAS model is directly related to its capacity to estimate its flight dynamics with minimum computational resources. The literature describes several techniques to estimate accurate aircraft flight dynamics. Most of them are based on system identification. This paper presents an alternative methodology to obtain complete model of the S4 and S45 unmanned aerial systems. The UAS-S4 and the UAS-S45 models were divided into four sub-models, each corresponding to a specific discipline: aerodynamics, propulsion, mass and inertia, and actuator. The‘‘aerodynamic" sub-model was built using the Fderivatives in-house code, which is an improvement of the classical DATCOM procedure. The ‘‘propulsion" sub-model was obtained by coupling a two-stroke engine model based on the ideal Otto cycle and a Blade Element Theory(BET) analysis of the propeller. The ‘‘mass and the inertia" sub-model was designed utilizing the Raymer and DATCOM methodologies. A sub-model of an actuator using servomotor characteristics was employed to complete the model. The total model was then checked by validation of each submodel with numerical and experimental data. The results indicate that the obtained model was accurate and could be used to design a flight simulator.     

地球同步轨道薄膜太阳帆的姿态轨道控制方法

薄膜太阳帆（FSS）是集推进、发电和姿轨控功能于一体化的超大型挠性太阳帆式航天器，通过调整薄膜反射率产生可变推力和力矩，实现其姿态和轨道运动控制。结合薄膜太阳帆在地球同步轨道运行时的受力特性进行了轨道漂移分析。通过建立薄膜太阳帆动力学模型及受力模型，提出了调整帆面角度轨道修正方法以及基于薄膜光压力矩角动量卸载的长期在轨对日定向面内双轴动量轮稳定控制方法。通过系统仿真验证表明所提的轨道修正和对日定向控制方法是合理有效的，可使薄膜太阳帆长期在定点位置维持对日定向。     

Topology optimization in lightweight design of a 3D-printed flapping-wing micro aerial vehicle

Topology optimization is an effective method to obtain a lightweight structure that meets the requirements of structural strength. Whether the optimization results meet the actual needs mainly depends on the accuracy of the material properties and the boundary conditions, especially for a tiny Flapping-wing Micro Aerial Vehicle (FMAV) transmission system manufactured by 3D printing. In this paper, experimental and numerical computation efforts were undertaken to gain a reliable topology optimization method for the bottom of the transmission system. First, the constitutive behavior of the ultraviolet (UV) curable resin used in fabrication was evaluated. Second, a numerical computation model describing further verified via experiments. Topology optimization modeling considering nonlinear factors, e.g. contact, friction and collision, was presented, and the optimization results were verified by both dynamic simulation and experiments. Finally, detailed discussions on different load cases and constraints were presented to clarify their effect on the optimization. Our methods and results presented in this paper may shed light on the lightweight design of a FMAV.     

类IXV飞行器初期再入制导与姿态控制方法研究

摘要： 针对类IXV飞行器无翼式升力体构型及采用RCS/尾襟翼组合控制特点，研究其初期再入段的高精度制导与姿态控制方法.设计带过程约束的数值预测 校正制导律以提高制导系统的鲁棒性及精确性；根据其执行机构配置特点，设计基于RCS的航向控制律及基于RCS/气动舵的纵、横向复合控制律，并采用鲁棒伺服LQR技术进行控制参数快速设计.通过蒙特卡洛打靶仿真来验证算法的精度及鲁棒性.     

超大口径环形天线包带展开过程动力学仿真

中间柔性包带是环形可展开天线的重要组成部分。中间包带拔销器解锁后，复材包带与环形桁架同步展开。因复材包带柔性较强，它会绕根部固定端进行回弹，因此展开过程存在金属接头和桁架上复材薄壁管件碰撞风险。随着天线口径增大，该风险会持续增大。基于柔性多体动力学理论对超大型口径环形可展开天线包带展开过程进行动力学建模仿真，并在此基础上分析得出包带展开过程金属接头到环形桁架最小距离主要和复材包带阻尼率以及桁架预展速度相关。通过进一步研究发现：复材包带阻尼率越高，展开过程金属接头到环形桁架最小距离越大；桁架预展速度越快，展开过程金属接头到环形桁架最小距离越小。此外，对逆止回弹机构失效这一在轨极端条件下包带展开过程进行建模仿真，分析得出包带在该条件下展开过程金属接头到环形桁架最小距离变化规律。该研究可为超大口径环形天线结构优化设计及包带在轨展开预示提供依据。     

基于时标分解的弹性高超声速飞行器智能控制

考虑弹性高超声速飞行器纵向动力学模型，提出了一种基于时标分解的智能控制方法。考虑刚体状态和弹性模态具有不同的时标特性，采用奇异摄动理论进行快慢时标分解，将模型转换为刚体慢变子系统和弹性快变子系统。针对刚体子系统考虑动力学不确定，基于平行估计模型构造表征不确定逼近效果的预测误差，结合跟踪误差给出复合学习控制策略。针对弹性子系统设计自适应滑模控制稳定弹性模态。通过李雅普诺夫稳定性分析可证系统状态一致终值有界。仿真表明所提出的控制方法能够实现刚弹模态的稳定收敛，且具有更高的跟踪精度、更好的学习性能和更快的收敛速度。     

大跨时空任务背景下的太阳能无人机任务规划技术研究进展

通过任务规划技术合理的优化太阳能无人机的飞行轨迹和动力学参数，能够有效提高太阳能无人机的能量利用率，使其胜任许多大范围跨时间跨空间飞行任务。从能量建模、续航评估和能量管理策略3个方面对大跨时空任务背景下太阳能无人机任务规划技术的研究进展进行了综述。在能量建模方面，介绍了当前主流的太阳辐射模型和能量生产基本框架；在续航评估方面，分析了目前的指标设计和应用方法；在能量管理策略方面，从能量综合应用、风力滑翔机制、轨迹优化方法和面向特定任务的应用4个角度，梳理了当前的研究现状。最后，对该领域未来可能的研究方向进行了展望。     

北斗工程IGSO/MEO/GEO发射轨道设计

随着我国航天事业的蓬勃发展，运载火箭发射要求也呈现多样化。北斗卫星导航系统是我国自行研制的全球卫星导航系统，经历三步跨越式发展，目前已经全面建成。CZ-3A系列火箭承担了北斗工程全部发射任务，该工程对火箭倾斜同步转移轨道（IGTO）、中圆转移轨道（MTO）、地球同步转移轨道（GTO）新类型轨道要求。介绍了该类轨道特点，讨论了火箭发射方案、发射轨道设计及高空风双向补偿方法。实际飞行考核充分证明了发射轨道设计的正确性，设计方法确保了北斗工程全部发射任务取得圆满成功，为北斗工程顺利实施奠定了基础。     

基于改进YOLO V5的无人机航拍图像小目标检测方法

本文针对无人机航拍目标检测技术中目标聚集、目标较小及实时性差等问题,将YOLO V5的主干架构进行改进,简化Neck网络,提出了一种提高检测速度又能准确识别的无人机航拍图像检测技术方案。经过仿真实验测试,改进后的YOLO V5网络在保持识别精度的同时,检测速率提升了31%,满足无人机在航拍作业时对于准确性与实时性的要求。