临近空间高超声速跳跃滑翔式目标自适应跟踪模型

针对临近空间高超声速跳跃式滑翔目标跟踪问题,在将加速度建模为具有正弦波（SW）自相关随机过程的基础上,提出一种自适应非零均值正弦波相关（ANM-SW）模型。其核心是对正弦波相关模型进行均值补偿构建ANM-SW模型,并推导了模型状态方程;为深入分析均值补偿的作用,分别从时域和频域的角度探讨了自适应非零均值模型的物理本质;此外,为进一步说明模型的适应性问题,结合Kalman滤波推导了SW及ANM-SW模型状态更新的系统动态误差,验证了ANM-SW模型在机动适应方面的优越性;最终仿真表明与SW模型相比,ANM-SW模型在跟踪精度及机动适应能力方面具有一定的优势性。     

近地卫星严格回归轨道保持控制

研究了近地卫星基于严格回归参考轨道的轨道保持控制方法：将卫星编队理论引入单星绝对轨道保持控制,提出了"虚拟卫星编队"的概念,分析了卫星轨道相对于参考空间轨迹在轨道摄动情况下的偏离状态及变化趋势,然后根据卫星编队相对运动学,推导出了偏离状态与虚拟卫星编队构形参数之间的对应关系,并设计了以轨道参数超调、偏置及阈值触发为特征的管道保持控制策略。数值仿真结果表明,使用该控制策略能够将卫星轨道保持在以空间参考轨迹为中心的轨道管道内,并且有效减少了因周期性轨道摄动波动造成的管道保持控制量和控制频次。研究成果对于有空间轨迹回归要求的卫星轨道保持控制具有指导意义。     

非接触转子振动位移采集系统测试误差

对基于叶尖定时测量原理开发的非接触转子振动位移采集系统(NRDMS)测试误差进行了研究分析。将模拟叶片振动标准信号作为采集系统测试的输入信号,研究了测试对象参数和采集系统时基信号对测试结果误差的影响,理论和测试结果分析表明:测试误差主要受采集系统时基信号和转速的影响,采集系统的最大引用误差为0.066%。      

Framework and development of data-driven physics based model with application in dimensional accuracy prediction in pocket milling

In the manufacturing of thin wall components for aerospace industry, apart from the side wall contour error, the Remaining Bottom Thickness Error (RBTE) for the thin-wall pocket component (e.g. rocket shell) is of the same importance but overlooked in current research. If the RBTE reduces by 30%, the weight reduction of the entire component will reach up to tens of kilograms while improving the dynamic balance performance of the large component. Current RBTE control requires the off-process measurement of limited discrete points on the component bottom to provide the reference value for compensation. This leads to incompleteness in the remaining bottom thickness control and redundant measurement in manufacturing. In this paper, the framework of data-driven physics based model is proposed and developed for the real-time prediction of critical quality for large components, which enables accurate prediction and compensation of RBTE value for the thin wall components. The physics based model considers the primary root cause, in terms of tool deflection and clamping stiffness induced Axial Material Removal Thickness (AMRT) variation, for the RBTE formation. And to incorporate the dynamic and inherent coupling of the complicated manufacturing system, the multi-feature fusion and machine learning algorithm, i.e. kernel Principal Component Analysis (kPCA) and kernel Support Vector Regression (kSVR), are incorporated with the physics based model. Therefore, the proposed data-driven physics based model combines both process mechanism and the system disturbance to achieve better prediction accuracy. The final verification experiment is implemented to validate the effectiveness of the proposed method for dimensional accuracy prediction in pocket milling, and the prediction accuracy of AMRT achieves 0.014 mm and 0.019 mm for straight and corner milling, respectively.     

Modeling and experiment of grinding wheel axial profiles based on gear hobs

Hobbing is one of the crucial gear manufacturing processes with high precision and high efficiency. In order to improve the accuracy of hobbing and hob relief grinding, more precise grinding wheels are demanded for relief grinding in the production of gear hobs. In this paper, a new and accurate mathematical method for calculating the axial profile of grinding wheel based on the corresponding gear hob to be ground is proposed. Considering that most researches have been conducted to focus on the optimization of hob geometric feature and only can be applied to a specific type of hand of helix and rake angle of gear hobs. The method in this paper can be served as a general algorithm for generating axial profile of grinding wheels on the basis of the spatial envelope theory, the principle of coordinate system transformation, and studies on normal profile of single-tooth. The accuracy of grinding hobs is based on applying the approach in practical manufacturing. Taking two typical different kinds of pre-grinding gear hobs as examples for calculation and experiment, the results of tooth profile errors strengthen the position that the validity and feasibility of this method, it can be employed for gear hob design and grinding processing.     

Influence of leading edge with real manufacturing error on aerodynamic performance of high subsonic compressor cascades

To investigate the influence of real leading-edge manufacturing error on aerodynamic performance of high subsonic compressor blades, a family of leading-edge manufacturing error data were obtained from measured compressor cascades. Considering the limited samples, the leading-edge angle and leading-edge radius distribution forms were evaluated by Shapiro-Wilk test and quantile–quantile plot. Their statistical characteristics provided can be introduced to later related researches. The parameterization design method B-spline and Bezier are adopted to create geometry models with manufacturing error based on leading-edge angle and leading-edge radius. The influence of real manufacturing error is quantified and analyzed by self-developed non-intrusive polynomial chaos and Sobol’ indices. The mechanism of leading-edge manufacturing error on aerodynamic performance is discussed. The results show that the total pressure loss coefficient is sensitive to the leading-edge manufacturing error compared with the static pressure ratio, especially at high incidence. Specifically, manufacturing error of the leading edge will influence the local flow acceleration and subsequently cause fluctuation of the downstream flow. The aerodynamic performance is sensitive to the manufacturing error of leading-edge radius at the design and negative incidences, while it is sensitive to the manufacturing error of leading-edge angle under the operation conditions with high incidences.     

FC-AE-1553网络传输性能评价

为了提高航天航空网络传输性能,提出一种通用的FC-AE-1553网络传输效率计算方法并研制高性能FC-AE-1553节点卡.首先,对FC-AE-1553网络的消息传输过程进行详细分析,分析信息类型,给出传输帧的格式建议,通过分析FC-AE-1553协议中各类消息传输的时间参数,结合FC标准中对通信时间的要求,提出FC-AE-1553网络交换中各种消息类型的通信时间计算公式.然后, 针对无差错传输和有差错传输两种情况,给出了网络传输效率的计算方法.最后,通过仿真分析数据帧净荷长度、节点处理时间、交换中序列数量、传输误码率、丢包率等参数对FC-AE-1553网络传输效率的影响,给出了网络优化设计的建议.依托某航天工程任务,研制了基于XC5VFX100T和MPC8536E的FC-AE-1553节点卡.实验结果表明:丢包对传输效率的影响可忽略;数据帧净荷为2 048 B,数据帧数量为16时,传输效率可达到77.2%.      

等效原理算法在不同等效面下的误差分析

等效原理算法(EPA)借鉴了区域分解的思想,并基于惠更斯等效原理实现了对大规模散射问题的计算.本文对EPA中的等效原理算子(EPO)进行了误差分析,选取了立方体、球体和进行了光滑处理的立方体等作为等效面寻找误差来源,并提出了误差改进的建议.根据计算结果,等效磁流在等效面上描述的误差一般集中在等效面表面的几何不连续处,且主要受等效面上的法向向量不连续性和基函数的选取的影响.故在选取等效面时应尽量考虑使用平滑的等效面,而不是直接使用立方体等效面.      

一种星间设备系统偏差的标定方法

针对Ka波段测距体制中星间测距设备系统偏差标定困难从而影响自主导航精度的问题,提出用星地无线电双向时间比对的方法标定星间设备系统偏差。通过两条星地双向链路并在这两颗卫星间建立一条星间双向链路进行标定。结果表明：该方法能够标定星间设备系统偏差,其RMS优于1ns,从而起到提高星间时间同步精度的目的。     

姿态角幅值约束下的太阳帆Lissajous轨道保持控制

太阳帆航天器以两姿态角作为轨道控制输入时, 其轨道动力学方程具有非仿射非线性特性. 通过人工平动点处线性化获得的线性系统可完成太阳帆航天器轨道保持控制器的分析与设计. 由于线性近似模型为有误差模型, 存在近似有效范围约束, 表现为轨道高度约束和姿态角幅值约束. 本文研究了姿态角幅值约束对线性近似模型有效性的影响, 通过计算给出满足近似误差要求的姿态角幅值约束. 当控制输入存在幅值约束时, 控制器轨道修正能力受到束缚. 通过研究姿态角幅值约束下的最大允许入轨误差, 设计了最大允许入轨误差下线性二次型调节器(LQR)用于轨道保持控制, 并将控制器应用于太阳帆日地三体系统非线性模型中, 实现了日地人工L₁点Lissajous轨道最大允许入轨误差的控制收敛和良好精度下的轨道保持控制.