Sliding mode control based guidance law with impact angle constraint

The terminal guidance problem for an unpowered lifting reentry vehicle against a sta- tionary target is considered. In addition to attacking the target with high accuracy, the vehicle is also expected to achieve a desired impact angle. In this paper, a sliding mode control （SMC）-based guidance law is developed to satisfy the terminal angle constraint. Firstly, a specific sliding mode function is designed, and the terminal requirements can be achieved by enforcing both the sliding mode function and its derivative to zero at the end of the flight. Then, a backstepping approach is used to ensure the finite-time reaching phase of the sliding mode and the analytic expression of the control effort can be obtained. The trajectories generated by this method only depend on the initial and terminal conditions of the terminal phase and the instantaneous states of the vehicle. In order to test the performance of the proposed guidance law in practical application, numerical simulations are carried out by taking all the aerodynamic parameters into consideration. The effec- tiveness of the proposed guidance law is verified by the simulation results in various scenarios.     

Accuracy enhancement of the spherical actuator with a two-level geometric calibration method

This paper presents a two-level geometric calibration method for the permanent magnet （PM） spherical actuator to improve its motion control accuracy. The proposed actuator is com- posed of a stator with circumferential coils and a rotor with multiple PM poles. Due to the assembly and fabrication errors, the real geometric parameters of the actuator will deviate from their design values. Hence, the identification of such errors is critical for the motion control tasks. A two-level geometric calibration approach is proposed to identify such errors. In the first level, the calibration model is formulated based on the differential form of the kinematic equation, which is to identify the geometric errors in the spherical joint. In the second level, the calibration model is formulated based on the differential form of torque formula, which is to calibrate the geometric parameters of the magnetization axes of PM poles and coils axes. To demonstrate the robustness and availability of the calibration algorithm, simulations are conducted. The results have shown that the proposed two-level calibration method can effectively compensate the geometric parameter errors and improve the positioning accuracy of the spherical actuator.     

舰载直升机金属动部件寿命控制技术研究

在分析现役老龄化舰载直升机动部件载荷特点的基础上,结合直升机所处的海洋腐蚀环境,讨论了舰载直升机的损伤类型和损伤容限寿命管理方法在其寿命分析中的应用,比较了损伤容限法应用于舰载直升机动部件与应用于固定翼飞机的不同点,重点讨论了损伤容限方法应用于工程实践亟待解决的关键技术。     

民用飞机维修目标与要求的指标体系研究

维修目标与要求(MORs)是为了能够并便于对产品进行维修而对航空器设计、维修和保障所提出的目标与要求,是设计、使用、维修、成本、效率等多种因素的综合权衡结果,也是维修工程学要实现的具体要求和指标。本文立足民用飞机,结合自身民机维修经验,从MORs指标确定的风险、过程、指标的分类等方面对MORs及其指标进行了研究。     

单天基平台测向的空间非合作目标跟踪

针对仅含角度测量信息的单个天基平台可观测性较弱的问题,提出了一种含脉冲机动检测的空间非合作目标跟踪算法,并设计了非合作目标实时跟踪数据处理流程.该算法利用抗差估计技术和UKF（Unscented Kalman Filter,无迹卡尔曼滤波）算法构造目标跟踪滤波器,并综合残差多项式拟合和新息分布特征等方法实现目标机动检测,在天基平台观测信息类型有限和观测几何较差的情况下,可以同时排除孤立野值和成片测量野值的影响,实现非合作机动目标的连续稳定跟踪.数值实验验证了算法的可行性和有效性,也表明了跟踪精度和可靠性与测量精度密切相关.     

一种基于稀疏分解的微多普勒频率估计算法

目标微动特性和微多普勒特征分析在真假目标识别方面发挥了重要作用。由于微动目标雷达同波具有非线性、多分量性等特征,需要相应的具有高分辨力、低交叉项、大的动态范围的分析工具,才能较好地揭示目标微多普勒特征。稀疏分解方法中的匹配追踪（MP）具有频域高分辨能力,对于信号细微特征提取具有很好的效果。研究了基于匹配追踪的微多普勒频率估计问题,该方法可以准确提取出目标微多普勒频率,为后续的目标识别提供了重要的依据。-     

民用飞机通用地面支援设备选型程序浅析

为了满足航空公司/维修单位高效率、低成本的要求,在飞机的设计过程中,尽量减少专用地面支援设备的种类,以通用地面支援设备取代,成为了飞机主制造商及其供应商共同努力的目标,也成为了一种发展趋势。因此,在飞机运营及维护、维修过程中,通用地面支援设备的选型及程序显得越来越重要。     

新支线103架机完成高寒试验试飞北大核心

2014年1月18日,ARJ21—700飞机103架机在内蒙古海拉尔顺利完成高寒地面试验和高寒飞行试验,并由海托尔东山机场经停呼和浩特白塔机场后,转场至西安阎良机场。     

一种基于机动辨识预测的空空导弹导引律

现有的空空导弹导引头在有噪声和干扰的环境下获得目标精确信息存在时间延迟,且新一代目标的机动能力更强,不对导弹加以补偿会造成较大脱靶量,所以需对目标状态有效预测。针对新一代目标规避空空导弹常用的大机动模式,为满足新一代空空导弹发展需求,设计了一种新型复合导引律。从目标自身出发,研究高机动目标规避导弹采用的典型机动形式,对机动轨迹进行离线建模,构建具有扩展能力的目标机动模型库。设计自适应滤波器对测量噪声进行降噪。同时,利用模型库设计了机动辨识预测器,对目标实际机动进行在线辨识。基于在线辨识的结果对目标机动进行预测,并对时间延迟进行补偿和修正,实现对高机动目标的精确打击。仿真结果表明:该方法对不同类型的机动目标均有较高的预测精度和命中精度。     

基于红外视频图像的目标跟踪技术探讨?

随着科技的不断进步，相应的目标跟踪技术也得到了快速的发展，尤其是视频目标跟踪，已经成为计算机视觉方面中比较重要的问题，社会各界对此引起了广泛的关注。论文阐述了红外成像的基本概念、视频图像的预处理、模块匹配目标跟踪技术以及算法的融合，为红外视频图像的目标跟踪技术的发展提供理论基础。