Backstepping Sliding Mode Trajectory Tracking via Extended State Observer for Quadrotors with Wind Disturbance

To overcome nonlinear, underactuated and external wind disturbances problems for the 6-DOF (degrees of freedom) quadrotor unmanned aerial vehicle (UAV) system, a backstepping sliding mode control algorithm based on high-order extended state observer (ESO) is proposed. Based on the hierarchical control principle, the quadrotor UAV dynamic system is decomposed into position subsystem and attitude subsystem to facilitate the backstepping control design. Moreover, the EXO is used to estimate the remaining unmeasurable states and the external wind disturbances online. The advantages of the controllers are that they can not only ensure good tracking performance, but also deal with uncertain external disturbances. To imitate the real situation as much as possible, the external wind disturbances are composed of four basic wind models in this paper. The tracking error and estimate error of the design methods are shown to arbitrarily small by using Lyapunov theory. Finally, the effectiveness and superiority of the proposed control algorithm are proved by the simulation.

     

贵州省气象档案管理系统建设

贵州省气象档案管理系统的研究与开发,解决了贵州省气象信息中心在日常工作中气象档案收集至归档之间的脱节问题,减少了工作量,为档案管理员提供了完整的档案业务功能。它涵盖了档案的收、管、存、用的全过程,实现对各种档案种类进行有效的组织和管理,初步建立了贵州省气象档案的自动化管理,在一定程度上提高了贵州省气象档案管理水平。     

Optimization of uncertain acoustic metamaterial with Helmholtz resonators based on interval model

Uncertainties existing in the acoustic metamaterial may strongly affect its unusual properties. Aiming at this actuality, the interval model is introduced to treat with uncertainties existing in the acoustic metamaterial with Helmholtz resonators. Frequency intervals in which the sound intensity transmission coefficients are certainly less than the required value and the effective bulk moduli are certainly negative are defined as conservative approximations. Frequency intervals in which the sound intensity transmission coefficients may be less than the required value and the effective bulk moduli may be negative are defined as unsafe approximations. The proportion of the conservative approximation and the unsafe approximation is defined as an approximate precision. Based on the quantification of uncertainties of the sound intensity transmission coefficients and the negative effective bulk moduli, an optimization model for the interval acoustic metamaterial with Helmholtz resonators is constructed. Numerical results showed that even suffering from effects of interval parameters, unusual properties of the optimized acoustic metamaterial (such as the bandgap of the sound transmission and the negative effective bulk modulus) could be improved.     

电控柴油机分缸均衡控制算法及试验

柴油机各个气缸的进气量、喷油量、燃烧等存在差异,导致气缸间存在做功差异,直接影响柴油机转速的平稳性以及排放性能等。针对位置式电控柴油机,采用PI闭环控制,通过瞬时转速信号识别并计算各缸的工作差异,利用分缸均衡控制算法对油量进行补偿修正。试验结果显示低转速稳态工况转速波动由7 r/min降至3 r/min,各缸工作不均匀度由±5 r/min降至±2 r/min,在瞬态过程和高转速3 400 r/min时该算法仍然适用有效。     

基于模糊层次分析的动态联盟伙伴选择策略

论述了基于模糊层次分析(AHP)的动态联盟伙伴选择策略。综合运用AHP方法和模糊决策方法构建了动态联盟伙伴选择的排序模型 ,通过求解该模型来得到参考排序值 ,力求使排序的结果能够客观、公正地反映不精确决策所蕴含的客观规律 ,以保证选择策略的准确性     

Nonlocal variational image segmentation models on graphs using the Split Bregman

Variational functionals such as Mumford-Shah and Chan-Vese methods have a major impact on various areas of image processing. After over 10 years of investigation, they are still in widespread use today. These formulations optimize contours by evolution through gradient descent, which is known for its overdependence on initialization and the tendency to produce undesirable local minima. In this paper, we propose an image segmentation model in a variational nonlocal means framework based on a weighted graph. The advantages of this model are twofold. First, the convexity global minimum (optimum) information is taken into account to achieve better segmentation results. Second, the proposed global convex energy functionals combine nonlocal regularization and local intensity fitting terms. The nonlocal total variational regularization term based on the graph is able to preserve the detailed structure of target objects. At the same time, the modified local binary fitting term introduced in the model as the local fitting term can efficiently deal with intensity inhomogeneity in images. Finally, we apply the Split Bregman method to minimize the proposed energy functional efficiently. The proposed model has been applied to segmentation of real medical and remote sensing images. Compared with other methods, the proposed model is superior in terms of both accuracy and efficient.     

实矩阵两类广义逆的迭代算法

将计算实矩阵的Moore-Penrose逆和Drazin逆转化为线性矩阵方程组的求解问题,然后采用修正共轭梯度法求线性矩阵方程组的一般解,并通过简单的矩阵乘法运算或者直接得到实矩阵的Moore-Penrose逆和Drazin逆.修正共轭梯度法不同于通常的共轭梯度法,它不要求涉及的线性代数方程组的系数矩阵正定、可逆或者列满秩,因此总是可行的.数值算例表明,这种算法是有效的.     

基于快速响应湿度传感器的无线呼吸检测系统

呼吸功能的实时检测对有呼吸功能障碍的人群十分重要.基于纳米材料湿度传感器和Zig Bee无线网络技术设计了一种呼吸检测系统,该系统由四部分组成:湿度传感器探头、数据采集节点、数据接收节点、基于VC++的MFC平台开发的呼吸功能检测软件.系统实现了呼吸频率记录、呼吸暂停报警、呼吸信号波形实时显示等功能.实验对几位志愿者进行呼吸功能检测,验证了系统的有效性.呼吸检测系统具有响应和恢复快、能够检测急促呼吸、受外界干扰小、无线检测、携带性强等特点.     

灰色Verhulst 模型背景值优化及其应用

鉴于背景值是影响灰色建模精度的重要因素之一, 提出一种灰色Verhulst 模型中背景值的优化方法. 基于灰色Verhulst 模型时间响应式的Logistic 函数形式和背景值的几何意义, 利用积分中值定理研究背景值与发展系数之间的数量关系; 采用最小二乘法对新参数进行估计, 还原原始参数估计值, 使得优化的背景值模型同时具备无偏性和最小误差性. 案例分析表明, 背景值优化的模型改善了模拟精度, 验证了模型的有效性和可行性.