差动变压器式位移传感器的仿真建模研究

差动变压器式位移传感器（LVDT）具有工作可靠性高、输出电压准确度高、线性度好等优点,在伺服系统中得以广泛应用。但传统的设计周期长、成本高,短时间内难以设计出线性度好的传感器。提出使用Maxwell建立传感器模型的方法,利用Maxwell快速改变模型尺寸的优势,对影响传感器性能的补偿线圈绕法进行了仿真。经试验验证,该模型可有效地模拟真实产品,显著地提高实际工程中传感器的设计效率及产品的线性度。     

浮球平台刚性的计算与实验研究

本文从浮球平台的结构特点出发,找到了适合于该复杂结构的三维有限元网格的分法,并编制了相应的单元及节点信息生成程序。使用ADINA程序计算了该结构的位移值,分析了其刚度,并与实验值作了比较,证明了本文方法的可靠性。     

基于强度和刚度可靠度的结构优化设计

以结构系统的可靠性作为结构的优化控制参数。用改进的分枝限界法判认主要失效模式。用PNET法计算结构系统的可靠度。导出了强度、刚度可靠度的灵敏度分析表达式。提出最佳矢量型法的迭代公式，有效地求解了结构在系统可靠度约束下的最小重量设计问题，算例的结果说明了方法的有效性。     

A novel variable structure multi-model approach based on error-ambiguity decomposition

Model Set Adaptation (MSA) plays a key role in the Variable Structure Multi-Model tracking approach (VSMM). In this paper, the Error-Ambiguity Decomposition (EAD) principle is adopted to derive the EAD-MSA criterion that is optimal in the sense of minimizing the square error between the estimate and the truth. Consequently, the EAD Variable Structure first-order General Pseudo Bayesian (EAD-VSGPB1) algorithm and the EAD Variable Structure Interacting Multiple Model (EAD-VSIMM) algorithm are constructed. The proposed algorithms are tested in two groups of maneuvering target tracking scenarios under different modes and observation error conditions. The simulation results demonstrate the effectiveness of the EAD-VSMM approach and show that, compared to some existing multi-model algorithms, the proposed EAD-VSMM algorithms achieve more robust and accurate tracking results.     

大型卫星姿态机动的滑模变结构控制技术

研究了大型卫星三轴大角度姿态机动控制。建立了以控制力矩陀螺作为执行机构的大型卫星姿态动力学方程,针对快速性和鲁棒性要求,设计了一种滑模变结构控制器。控制器基于反馈四元数,避免了源自三轴大角度机动欧拉角描述的奇异性,且滑动模态能满足Lyapunov意义的渐近稳定。仿真结果验证了该控制器的有效性和优良性能。     

Attitude tracking control for variable structure near space vehicles based on switched nonlinear systems

An adaptive robust attitude tracking control law based on switched nonlinear systems is presented for a variable structure near space vehicle (VSNSV) in the presence of uncertainties and disturbances. The adaptive fuzzy systems are employed for approximating unknown functions in the flight dynamic model and their parameters are updated online. To improve the flight robust performance, robust controllers with adaptive gains are designed to compensate for the approximation errors and thus they have less design conservation. Moreover, a systematic procedure is developed for the synthesis of adaptive fuzzy dynamic surface control (DSC) approach. According to the common Lyapunov function theory, it is proved that all signals of the closed-loop system are uniformly ultimately bounded by the continuous controller. The simulation results demonstrate the effectiveness and robustness of the proposed control scheme.     

基于Kriging近似函数的变复杂度近似模型

为解决飞行器多学科不确定性设计与优化过程中多次调用计算复杂的高精度学科分析模型带来的计算复杂性问题，结合变复杂度建模思想和Kriging近似函数，建立了基于Kriging近似函数的变复杂度近似模型。该近似模型的构造基于较少的高精度模型取样点和较多的低精度模型取样点，在满足近似精度的要求下可大大减小高精度模型近似模型构造的计算成本。数学算例和某飞行器气动力变复杂度近似模型算例证明了该方法的有效性。     

挠性空间飞行器的双回路控制器设计

针对大型挠性空间结构频率低，阻尼小，铡体与各挠性模态之间互相耦合等特点，提出了一种双回路控制器的设计方法，回路的设计采用了最优滑动模态的变结构设计方法，且考虑了鲁棒稳定性问题。最后，给出了结果的数字仿真从仿真曲线可以看出，对于基于模态截断的大型挠性空间飞行器，该设计方法具有一定的鲁棒性。     

Magnetic levitation of large water droplets and mice

We report successful levitation of large water droplets and mice using a newly built variable gravity simulator. The simulator consists mainly of a superconducting magnet with a room temperature accessible experimental levitating space. The superconducting magnet generates a field and field gradient product that is large enough to levitate water and many other common liquids. The warm bore of the magnet has a diameter of 66 mm, large enough to levitate small mammals. We demonstrate that water drops up to 50 mm in diameter and young mice can be levitated in the system. The capability of levitating large water drops and biological systems offers new opportunities for conducting detailed and in-depth study of properties of fluids and biological systems in reduced gravity environments.     

A study on the quintic nonlinear beam vibrations using asymptotic approximate approaches

This paper intends to promote the application of modern analytical approaches to the governing equation of transversely vibrating quintic nonlinear beams. Four new studied methods are Stiffness analytical approximation method, Homotopy Perturbation Method with an Auxiliary Term, Max–Min Approach (MMA) and Iteration Perturbation Method (IPM). The powerful analytical approaches are used to obtain the nonlinear frequency–amplitude relationship for dynamic behavior of vibrating beams with quintic nonlinearity. It is demonstrated that the first terms in series expansions of all methods are sufficient to obtain a highly accurate solution. Finally, a numerical example is conducted to verify the integrity of the asymptotic methods.