流程图转变成箭线图的基本规则

本文详细地论述了由流程图演变成箭线网络图的整个过程。指出,通过添加虚箭线的方法可使流程图转变成箭线网络图,但它含有许多多余的虚箭线,因而不是最优箭线图。本文在理论研究及大量实践的基础上,确定了活动之间相互关系的4种形式,并针对这4种形式指出了4条去掉多余虚线的法则及一条添补必要虚线的法则.可以证明,用这些法则设计的网络图是最优网络图。 最后,文中简要介绍了从流程图转变成最优箭线图的计算机算法。编制的软件可在微机上实现网络图的自动设计及绘制、时间参数的计算等项工作。软件功能齐全,具有很大的实用价值。     

自由曲面构件的纤维铺放路径规划

针对复合材料纤维铺放工艺及其设备控制的特点,提出了复合材料构件CAE/CAM一体化纤维铺放路径优化设计方法。通过对构件模型的有限元分析,获得构件的内部应力分布,根据主应力的大小和方向合理规划出若干基准纤维铺放路径;提出了基于等距线、等分点原理的两种算法,对基准铺放路径进行均匀密化,实现整个构件曲面的纤维铺放路径规划;讨论了铺丝宽度和铺放精度的控制策略,并给出了铺放头压辊中心控制轨迹,以满足纤维铺放机械手的控制需求。     

电弧熔丝增材制造复合填充路径规划算法

合理的路径规划可以提高电弧熔丝增材制造成形零件的表面质量和强度。针对电弧熔丝增材制造的特点,将多种增材制造路径规划算法相结合,提出了一种复合路径规划算法,实现了单空洞截面的填充,并进一步讨论了其他类型截面的路径规划方法。在填充截面过程中,内外表面采用轮廓偏置路径填充,保证了零件的表面质量;零件内部采用改进的扫描线算法进行填充,减少了空行程,提高了成形效率。实验验证了本文算法填充复杂截面轮廓的可行性。     

飞机大尺寸自动化柔性测量技术研究进展

飞机大尺寸零部件具有结构复杂、外形尺寸大等特点。传统的单一测量手段如激光跟踪仪,因测量效率低等问题,越来越难以满足飞机智能制造的高精度、高效率的测量需求。大尺寸自动化柔性测量技术作为一种新兴的组合式测量方法,突破了单一测量设备测量效率低的难题,以其高精度、高效率测量的优势,在航空测量领域展现了极强的发展应用前景。针对飞机制造过程中大尺寸自动化柔性测量技术的研究,本文首先综述了飞机大尺寸测量场构建的相关进展。其次,介绍了自动化柔性扫描路径规划的研究进展。然后,列举了柔性化测量在飞机蒙皮间隙测量、整机水平测量和数字化预装配等方面的应用现状。最终总结得出,飞机自动化柔性大尺寸测量技术的研究对提高飞机制造过程中的质量控制具有重要的实际意义。     

Online feedback motion planning for spacecraft obstacle avoidance using positively invariant sets

This paper investigates a novel reliable feedback motion planning algorithm for steering a spacecraft to the desired position while satisfying dynamics and environmental constraints, such as actuator constraints, unexpected state constraints, bounded disturbances, etc. The proposed algorithm, termed safeRRT1, applies positively invariant (PI) set transitions to an online sampling approach based on the asymptotically optimal rapidly-exploring random tree (RRT1). A time-varying safe corridor is generated which consists of a sequence of PI sets under the instantaneous constraints. A spacecraft is guaranteed to remain within the corridor when the feedback controllers corresponding to the PI set transitions are executed. Simulations of the spacecraft avoiding obstacles validate the feasibility and effectiveness of the proposed safeRRT1 algorithm.     

Improvement of the GRACE star camera data based on the revision of the combination method

The new release of the sensor and instrument data (Level-1B release 02) of the Gravity Recovery and Climate Experiment (GRACE) had a substantial impact on the improvement of the overall accuracy of the gravity field models. This has implied that improvements on the sensor data level can still significantly contribute to arriving closer to the GRACE baseline accuracy. The recent analysis of the GRACE star camera data (SCA1B RL02) revealed their unexpectedly higher noise. As the star camera (SCA) data are essential for the processing of the K-band ranging data and the accelerometer data, thorough investigation of the data set was needed. We fully reexamined the SCA data processing from Level-1A to Level-1B with focus on the combination method of the data delivered by the two SCA heads. In the first step, we produced and compared our own combined attitude solution by applying two different combination methods on the SCA Level-1A data. The first method introduces the information about the anisotropic accuracy of the star camera measurement in terms of a weighing matrix. This method was applied in the official processing as well. The alternative method merges only the well determined SCA boresight directions. This method was implemented on the GRACE SCA data for the first time. Both methods were expected to provide optimal solution characteristic by the full accuracy about all three axes, which was confirmed. In the second step, we analyzed the differences between the official SCA1B RL02 data generated by the Jet Propulsion Laboratory (JPL) and our solution. SCA1B RL02 contains systematically higher noise of about a factor 3–4. The data analysis revealed that the reason is the incorrect implementation of algorithms in the JPL processing routines. After correct implementation of the combination method, significant improvement within the whole spectrum was achieved. Based on these results, the official reprocessing of the SCA data is suggested, as the SCA attitude data are one of the key observations needed for the gravity field recovery.     

网络计划技术在落锤模项目中的应用

针对某型飞机油箱壳体落锤模加工周期长的问题,采用网络计划技术,找出关键因素和关键线路；打破常规,采用数控加工方法加工落锤模,并对其关键制造过程进行计划和控制,大大缩短了模具制造时间,满足了油箱落锤模的交付要求.     

基于梯度下降法的翼伞系统最优分段航迹规划

传统最优控制航迹规划一般以逆风精确着陆、控制能量小为优化目标，但传统最优控制的操纵过程一般是一条连续变化的曲线，工程上不易实施；与之相比，传统分段航迹规划操纵简单，工程上容易实施，能实现逆风精确着陆的目标，但控制能耗大。为了兼顾逆风精确着陆、能耗低和控制操作简单等目标，提出了一种基于梯度下降法的翼伞最优分段航迹规划方法。该方法将控制变量参数化，将逆风精确着陆、控制能耗小、能实现避障等多目标优化问题转化为加权单目标优化问题，并通过梯度下降法求解得到分段常值最优归航航迹。所提算法与基于伪谱法的最优控制规划航迹和基于遗传算法的分段规划航迹进行了对比，算法仿真结果表明本文提出的最优分段航迹规划法既可以实现着陆精度高、控制能量小、逆风着陆和避障的优化目标，同时规划的航迹又由分段常值实现控制，工程上容易实施，兼顾了最优控制航迹规划和分段航迹规划的优点。     

基于改进A-Star算法的隐身无人机快速突防航路规划

针对现代战争中隐身无人机（UAV）在高严密的组网雷达防御体系下的生存及突防问题,提出了基于改进A-Star算法的隐身无人机战区突防航路规划技术。首先对隐身无人机突防过程进行了分析建模,分别建立了隐身无人机的运动学模型、动态雷达散射截面特性和组网雷达探测概率的计算模型。然后针对传统算法在解决隐身突防问题时的不足,充分考虑所规划航路时的快速性和安全性要求,设计了改进A-Star算法。在算法中引入了多层变步长搜索策略和无人机的姿态角信息,结合秩K融合准则,通过每段航迹上隐身无人机被组网雷达系统的发现概率来判断新航迹点的可行性。仿真结果表明,改进A-Star算法能够在复杂的组网雷达系统下快速生成更优的战区突防航路,具有一定的应用价值。     

基于MBSE的副翼及其操纵系统研发技术及应用

飞机的设计研发是一项涉及多学科领域、多目标、多约束的复杂系统工程过程,系统耦合紧密、参与人员众多、设计信息庞杂,以文档为中心的需求管理等传统研发方法突显出一定的困难,亟需探索新的飞机设计研发方法。以副翼及其操纵系统为研究对象,对基于模型的系统工程(Model Based System Engineering,以下简称MBSE)方法进行了探索研究:采用达索MBSE方法论-MMS(Modeling Methodology for Systems,以下简称MMS),从使命、服务、功能和组件不同视角对副翼及其操纵系统研发的各个方面进行解析,进而完整定义系统;利用达索3D Experience平台,通过RFLP系统工程架构,进行了副翼及其操纵系统的需求开发、功能分析及逻辑架构设计,完成了需求、功能、逻辑架构、系统仿真、物理设计等模型的关联追溯,实现了以达索MBSE方法论为核心的研发技术的有效应用。