Topology optimization of joint load control with geometrical nonlinearity

This paper presents an extended topology optimization approach considering joint load constraints with geo-metrical nonlinearity in design of assembled structures. The geometrical nonlinearity is firstly included to reflect the structural response and the joint load distribution under large deformation. To avoid a failure of fastener joints, topology optimization is then carried out to minimize the structural end compliance in the equilibrium state while controlling joint loads intensities over fasteners. During nonlinear analysis and optimization, a novel implementation of adjoint vector sensitivity analysis along with super element condensation is introduced to address numerical instability issues. The degrees of freedom of weak regions are condensed so that their influences are excluded from the iterative Newton-Raphson (NR) solution. Numerical examples are presented to validate the efficiency and robustness of the proposed method. The effects of joint load constraints and geometrical nonlinearity are highlighted by comparing numerical optimization results.     

弹载大视场星惯组合深度融合导航技术

为了降低弹载星惯组合（Stellar-INS）飞行中段对调姿观星的要求，提高星惯组合姿态精度，提出了大视场（LFOV）星惯组合深度融合导航方法。小视场（NFOV）星敏感器输出星矢量为主，大视场星敏感器可同时输出姿态和星矢量信息，分别推导了基于星敏感器输出姿态和星矢量信息的观测方程，分析了星矢量和姿态观测方法之间的关联性。建立了包含星惯安装误差、陀螺误差以及初始平台误差角的星惯组合全误差项模型，基于线性卡尔曼滤波给出了深度融合导航方法。开展了数学仿真验证，分析了不同调姿观星路径约束下，大/小视场星惯组合性能差异。结果表明，大视场星惯组合深度融合导航方法不仅可以降低调姿观星约束要求，还可以实现组合姿态性能提升。     

Error constrained control of a pseudo-satellite with disturbance

This paper presents the control scheme of a pseudo-satellite in situations where error constraints, uncertainties, and external disturbances occur. The control scheme of a pseudo-satellite includes planar path following control scheme and altitude control scheme. In order to control the altitude of a pseudo-satellite, the backstepping technique is used to control the quality of air in the air balloon. To deal with the error constrained requirements of a pseudo-satellite’s position, a tan-type barrier Lyapunov function (TBLF) is proposed and incorporated with the guidance control schemes. Adaptive fuzzy disturbance observers are presented to estimate uncertainties and external disturbances. Rigorous stability analysis proves that the altitude error of the pseudo-satellite can be uniformly bounded, and the position error of which can be maintained within the range of constrained requirements, while all closed-loop signals are uniformly bounded regardless of uncertainties and disturbances.     

Stiffeners layout design of thin-walled structures with constraints on multi-fastener joint loads

The purpose of this paper is to present an extended topology optimization method for the stiffeners layout design of aircraft assembled structures.Multi-fastener joint loads and manufacturing constraints are considered simultaneously.On one hand,the joint loads are calculated and constrained within a limited value to avoid the failure of fasteners.On the other hand,the manufacturing constraints of the material distribution in the machining directions of stiffeners are implemented by an improved piecewise interpolation based on a beveled cut-surface.It is proven that the objective function is strictly continuous and differentiable with respect to the piecewise interpolation.The effects of the extended method with two different constraints are highlighted by typical numerical examples.Compared with the standard topology optimization,the final designs have clearly shown the layout of stiffeners and the joint loads have been perfectly constrained to a satisfying level.     

大型飞机整机涂装自动化实施探讨与展望

大型飞机整机涂装是飞机涂装领域中技术含量最高、难度最大的工艺,涉及表面整体打磨(2～3次)、表面清洗、表面处理、表面状态检测、喷涂等众多复杂工序,目前的实施过程主要依赖手工作业,但防护水平、外观质量等已经落后于实现自动化的汽车涂装.本文依据大型飞机涂装工艺程序特点,探讨各个工艺过程的自动化实施的关键研究内容,并就整机智能化涂装的可行性与重大意义进行展望.     

基于航路耦合容量的协同多航路资源分配

针对中国当前航路空域拥挤日益严重的问题,分3个步骤进行解决:第1步,对空域管制单元之间存在的交通流耦合因素进行分析,建立基于空域管制单元耦合因素的航路容量模型;第2步,为反映不同类型航班对计划到达时间变动范围的不同接受程度,定义了航班的延误成本函数和改航成本函数;第3步,在上述两步的基础上,为充分利用可行的航路空域资源...     

Impact time control guidance against maneuvering targets based on a nonlinear virtual relative model

Aiming at the problem of high-precision interception of air-maneuvering targets with impact time constraints, this paper proposes a novel guidance law based on a nonlinear virtual relative model in which the origin is attached to the target. In this way, the original maneuvering target is transformed into a stationary one. A polynomial function of the guidance command in the range domain with two unknown coefficients is introduced into the virtual model, one of the coefficients is determined to ...     

基于弹性网稀疏编码的空间目标识别

 传统的特征袋(BoF)模型在目标识别过程中假设每个局部特征点只关联特征词典中一个视觉单词。此外,l₁范数约束下的稀疏编码对于具有较强成对相关性的特征通常只选择一个特征,而不关注哪一个特征被选择。本文提出一种基于弹性网稀疏编码的特征袋模型。该模型利用尺度不变特征变换(SIFT)特征描述子构建特征字典,再通过弹性网回归模型求解每个描述子所对应的稀疏系数向量,最后将目标图像内的稀疏系数向量合并用于分类。与传统的特征袋模型和基于l₁范数稀疏编码的特征袋模型相比,该模型有较好的识别性能,并对视角变化具有较强的鲁棒性。在空间目标图像数据库上的实验验证了该模型的有效性。     

现场总线ARCNET及其应用

介绍一种新型的现场总线———ARCNET总线。ARCNET总线是一种令牌环式总线 ,具备高速性和延时可测性 ,非常适用于构成分布式的自动控制系统。文章以这种ARCNET总线应用于双足步行机器人控制系统为实例 ,分析了它的特点。     

新型双脚步推式微型进给机构的研究

相对于传统“尺蠖式”进给原理，模仿人走路的方式，提出“双脚步推式”进给原理。利用压电元件为驱动源，研制出在大范围内，具有很高分辨力，同时能够连续平稳进给的微型进给机构。该机构的优点概括为：１）不论压电元件的电致伸缩量是多么的有限，利用“双脚步推式”进给原理，可以实现连续平稳的大范围进给；２）在开环控制状态下，该机构能够得到高于０．１μｍ的位移分辨力；３）系统结构简单，控制容易，性能稳定。