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Hao Yang Bin Jiang Youmin Zhang 《International Journal of Control, Automation and Systems》2014,12(1):29-36
This paper studies the fault tolerant formation keeping problem of multi-agent systems with consideration of shortest connection topology. This is motivated by the requirement of low communication cost which largely depends on the communication length. Given a formation shape, a connection topology design method and its reconfiguration strategy are proposed in the sense that the whole connection path is shortest despite of communication faults. A control framework that combines the individual formation controller of each agent and connection topology is further presented. The stability of the whole system process is analyzed by switched system theories. Simulation results of unmanned aerial vehicles (UAVs) show the effectiveness of the proposed strategy. 相似文献
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基于四旋翼飞行器悬停状态下的位置及姿态信息,提出了一种离线的风场估计方法。首先根据Dryden大气紊流模型建立了四旋翼飞行器所处的风场环境,并通过分析有风情况下旋翼升力的变化,得到旋翼升力与风场信息(风速、风向)的函数关系式;接着利用牛顿-欧拉方法推导出有风扰动下的四旋翼动力学方程,并进一步设计了用于保持飞行器悬停状态的PID控制器;最后,基于悬停状态下四旋翼飞行器的位置姿态信息,计算得到飞行器所处的风场环境信息。MATLAB仿真结果表明所提方法在有紊流干扰的情况下,能够有效地提取出风场环境里的主风信息。 相似文献
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针对带末端角度和末端速度约束的无人机空中加油自主会合问题,设计了一种3维分数阶滑模导引律,使无人机在无加油机主动配合的情况下具备自主会合能力.首先,根据无人机与加油机之间的相对运动关系,设计了3维比例导引规律,使无人机能够到达期望的加油位置.其次,利用滑模控制的强鲁棒性特点以及分数阶微积分的精细控制特性,基于变结构理论和李雅普诺夫稳定性理论设计了一种带有末端角度约束的3维分数阶滑模变结构控制律,并用所设计的分数阶滑模控制律对3维比例导引指令进行重构,使无人机能以期望的末端追踪角度到达加油位置.然后,构造了速度指令生成器,对无人机的末端速度进行约束.最后,对所设计的导引律进行了仿真验证,仿真结果表明所设计出来的导引律能满足追踪角度和速度约束的要求. 相似文献
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A novel fault diagnosis method of bearing based on improved fuzzy ARTMAP and modified distance discriminant technique 总被引:1,自引:0,他引:1
Zengbing Xu Jianping Xuan Tielin Shi Bo Wu Youmin Hu 《Expert systems with applications》2009,36(9):11801-11807
This paper presents a novel intelligent diagnosis method based on multiple domain features, modified distance discrimination technique and improved fuzzy ARTMAP (IFAM). The method consists of three steps. To begin with, time-domain, frequency-domain and wavelet grey moments are extracted from the raw vibration signals to demonstrate the fault-related information. Then through the modified distance discrimination technique some salient features are selected from the original feature set. Finally, the optimal feature set is input into the IFAM incorporated with similarity based on the Yu’s norm in the classification phase to identify the different fault categories. The proposed method is applied to the fault diagnosis of rolling element bearing, and the test results show that the IFAM identify the fault categories of rolling element bearing more accurately and has a better diagnosis performance compared to the FAM. Furthermore, by the application of the bootstrap method to the diagnosis results it can testify that the IFAM has more capacity of reliability and robustness. 相似文献
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Youmin GuoYunbo Zhou Dengjie ChenHuangang Shi Ran RanZongping Shao 《Journal of power sources》2011,196(13):5511-5519
The effects of the current collection material and method on the performance of SOFCs with Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) cathodes are investigated. Ag paste and LaCoO3 (LC) oxide are studied as current collection materials, and five different current collecting techniques are attempted. Cell performances are evaluated using a current-voltage test and electrochemical impedance spectra (EIS) based on two types of anode-supported fuel cells, i.e., NiO + SDC|SDC|BSCF and NiO + YSZ|YSZ|SDC|BSCF. The cell with diluted Ag paste as the current collector exhibits the highest peak power density, nearly 16 times that of a similar cell without current collector. The electrochemical characteristics of the BSCF cathode with different current collectors are further determined by EIS at 600 °C using symmetrical cells. The cell with diluted Ag paste as the current collector displays the lowest ohmic resistance (1.4 Ω cm2) and polarization resistance (0.1 Ω cm2). Meanwhile, the surface conductivities of various current collectors are measured by a four-probe DC conductivity technique. The surface conductivity of diluted Ag paste is 2-3 orders of magnitude higher than that of LC or BSCF. The outstanding surface conductivity of silver may reduce the contact resistance at the current collector/electrode interface and, thus, contributes to better electrode performance. 相似文献
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Xin ZHANG Tao HUANG Bo WU Youmin HU Shuai HUANG Quan ZHOU Xi ZHANG 《Frontiers of Mechanical Engineering》2021,16(2):340-352
Frontiers of Mechanical Engineering - Deep learning has achieved much success in mechanical intelligent fault diagnosis in recent years. However, many deep learning methods cannot fully extract... 相似文献
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通过浮选实验先将典型烟煤分成高、中、低3个密度段,然后对3种不同密度原煤在沉降炉内进行热解和燃烧实验,研究原煤密度对颗粒物形成机理和特性的影响。实验采用低压撞击器(LPI)把颗粒物按不同粒径大小从0.03~10.0 μm共分13级,分别采集燃烧后的可吸入颗粒物。实验结果显示:低密度原煤对颗粒物形成的贡献最大,中密度次之,高密度最小,低密度原煤所含矿物质粒度最小,形成的焦的膨胀率、总孔体积和BET表面积最大,高密度原煤所含矿物质粒度最大,形成的焦的膨胀率、总孔体积和BET表面积最小,中密度原煤介于两者之间,3种密度原煤燃烧后形成的PM10颗粒物元素构成的相同点是:对于亚微米颗粒物,元素S+碱金属元素+其他元素>难熔元素,对于超微米颗粒物,难熔元素占80%以上,远远大于其他三类元素。 相似文献