快速原型制造技术及其发展前景

概述了快速原型技术的工作原理及特点,并对几种典的商品化ＲＰＭ工艺技术作了简要介绍了,对ＰＲＭ发展现状进行了综述,提出将ＰＲＭ技术用于纤维复合材料的制造是其发展的重要趋势。     

航空制造系统的设计、评价及其仿真

主要论述了系统仿真技术在航空制造领域中的应用。通过利用系统仿真软件模拟飞机引擎涡轮叶片制造工厂的现有及未来的生产过程,并比较两个系统的生产绩效,如年产量及生产过程库存水平、机器使用率、劳动力利用率,来评价这一未来的生产系统。     

企业投入产出方法与制造资源计划方法的结合研究

提出以企业基础信息平台为基础数据，在企业工序产品生产计划、外购品采购计划、成本计划、物料清单、成本核算等方面，实现企业投入产出方法与制造资源计划方法的结合。     

Influence and experiment of cable-net manufacturing errors on surface accuracy of mesh reflector antennas

Cable-net structures are of substantial importance in the construction of large mesh reflector antennas. Owing to the inevitable errors in their manufacturing process, the reflector surface accuracy deteriorates. This study makes a comprehensive investigation of random manufacturing errors during constructing the mesh reflector antennas, and analyze its influence on reflector surface accuracy. Firstly, the sensitivity of reflector surface accuracy with respect to the random errors of the unstressed cable length is mathematically deducted. Secondly, a non-button connecting method is proposed and analyzed to reduce manufacturing errors. Thirdly, two physical experiment models based on 2.62-meter mesh reflector antenna are made. Finally, numerical examples and experimental tests are given to demonstrate the effectiveness of the proposed method. Compared with the traditional method, the proposed method can effectively reduce the influence of the manufacturing errors on the reflector surface accuracy. Moreover, the reduction in the sizes of the nodes also reduces the risk of entanglement of the mesh reflector antenna during the deployment process, and thereby improves the deployment reliability.     

HLA/RTI下周期与非周期任务调度的实时性改进

为了把高层体系结构的标准应用到实时系统中,必须确保运行时支撑环境的实时性.联邦成员间相关的任务之间有优先顺序约束关系,在联邦成员内调度运行时较难提供可预测的响应,因而难以保证所有任务尤其是非周期任务的实时性.以任务调度理论的角度在联邦成员内部综合调度周期与非周期任务运行的D-EDF（Double-Earliest Deadline First）策略,既能舍弃部分冗余数据使周期性任务在截止时间前高效完成,又能调度非周期性任务规则的运行提高实时响应速度,使得联邦成员可以高效地处理有优先顺序约束关系的任务,进而改进了运行时支撑环境的实时性.最后证明了D-EDF调度策略的可行性.      

A triangle voting algorithm based on double feature constraints for star sensors

A novel autonomous star identification algorithm is presented in this study. In the proposed algorithm, each sensor star constructs multi-triangle with its bright neighbor stars and obtains its candidates by triangle voting process, in which the triangle is considered as the basic voting element. In order to accelerate the speed of this algorithm and reduce the required memory for star database, feature extraction is carried out to reduce the dimension of triangles and each triangle is described by its base and height. During the identification period, the voting scheme based on double feature constraints is proposed to implement triangle voting. This scheme guarantees that only the catalog star satisfying two features can vote for the sensor star, which improves the robustness towards false stars. The simulation and real star image test demonstrate that compared with the other two algorithms, the proposed algorithm is more robust towards position noise, magnitude noise and false stars.     

满足多终端约束的二次曲线迭代制导方法研究

某些空间载荷会对入轨精度和入轨姿态同时提出很高的要求,应用于运载火箭控制系统的摄动制导方法的入轨精度无法满足要求,而传统的迭代制导方法无法约束终端的入轨姿态。为此提出了一种满足多终端约束的二次曲线迭代制导方法,该方法通过二次曲线形式规划整个真空段的飞行制导程序角,实时满足位置、速度与终端姿态约束,从而可以使得火箭以期望姿态角实现高精度入轨。算例结果表明,该方法能同时保证高精度的入轨指标和入轨姿态,并能适应偏差状态、约束姿态角变化与轨道根数小幅变化,具有较高的工程应用价值。     

面向空间抓取任务的目标轮廓跟踪方法

在空间抓取任务中,视场背景复杂,光照条件变化剧烈,而且存在相对运动。文章提出了一种新的动态轮廓特征检测跟踪方法。首先在灰度梯度法基础上,引入形状匹配、面积筛选和自适应灰度阈值调整方法,提高了轮廓提取的鲁棒性。随后,基于该提取结果,利用图像序列的时域相关约束辅助GVFSnake算法进行轮廓跟踪,提升了动态检测速度。最后,考虑到空间抓取任务的实时性需求,采用CUDA运算架构对算法进行并行化处理,并对一组序贯图像序列进行了轮廓跟踪实验。实验结果表明,此方法在CUDA平台下轮廓跟踪速率达到了10帧/s,在保证轮廓检测的准确性的基础上,明显改善了检测速度。     

侵彻制导武器终端多约束最优制导律

针对侵彻型制导武器终端多约束制导问题,建立包含一阶弹体动力学的多约束制导模型,采用最优控制方法推导终端多约束制导问题的通解。根据终端约束与罚函数的关系,求解了实际工程中关心的3种最优制导律,并结合当前主流制导控制体制,在小角假设下,将其表述为便于工程实现的形式,即包含弹体动力学的最优比例导引制导律、弹道成型最优制导律和终端多约束最优制导律。理论分析和典型末制导条件仿真表明,后2种制导律可为侵彻制导武器终端位置与角度双约束以及位置、角度与加速度多约束制导问题提供理论基础和工程应用参考。     

具有碰撞角约束的三维圆轨迹制导律

 针对再入飞行器带碰撞角约束的导引问题,设计了一种新型三维(3D)制导律。改进并扩展了圆轨迹导引算法,定义了2个圆轨迹跟踪误差变量。通过对导引任务的分析,提出闭环修正导引方法。在此基础上,对再入飞行器制导过程的动力学方程进行解析推导,设计出能适应再入飞行器速度大小变化的三维闭环圆轨迹制导律(3CCGL)。数学仿真结果表明:此制导律能导引再入飞行器沿终端约束方向精确命中目标;同已有算法相比,该制导算法优势明显,其导引的飞行路径短,终端碰撞速度大,并能实现大角度转向攻击,大幅提高再入飞行器的末段机动能力。