共查询到19条相似文献,搜索用时 218 毫秒
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为解决汽车半主动悬架(Semi-Active Suspension,SAS)与电动助力转向(Electric Power Steering,EPS)集成系统在线故障诊断的问题,提出将小波分析方法应用到SAS与EPS集成系统传感器和ECU的故障诊断中。首先根据故障状态下传感器和ECU输出电压信号的突变特性,利用小波分析奇异性检测原理检测出突变信息。随后为能更精确地检测出突变信息,先使用小波阈值法对电压信号消噪,再对消噪后的电压信号进行检测。最后以SAS与EPS集成系统中扭矩传感器和ECU故障诊断为例进行试验研究。结果表明,小波分析方法能有效抑制信号噪声,并准确检测出故障和故障发生时刻,对集成控制系统的安全运行及故障诊断具有重要的工程应用意义。 相似文献
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介绍了一种基于线性集成霍尔传感器的铁磁材料痕迹检测方法。该方法是通过霍尔传感器测量磁化金属表面磁场大小以读取金属工件表面痕迹信息。试验结果表明,系统具有很好的成像效果。通过改进,用霍尔传感器阵列检测可以增大测量面积,提高扫描效率,具有广阔的应用前景。 相似文献
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A density-based fuzzy clustering technique for non-destructive detection of defects in materials 总被引:1,自引:1,他引:0
Hasanzadeh P.R. Reza A.H. Rezaie S.H.H. Sadeghi M.H. Moradi M. Ahmadi 《NDT & E International》2007,40(4):337-346
In non-destructive testing and evaluation of materials, defects contain visible aggregations of similar levels of brightness with large scale of correlation between them. In most cases, these brightnesses have no notable contrast relative to non-defect counterparts. However, the density and the size of the defect are visually the most notable features. In this paper, we have utilized human conception for classifying defects by the fusion of fuzzy clustering method and fuzzy logic rules based on the density and the size of the defect. The probability of detection and the probability of error are compared with the Bayes classifier. The proposed approach shows that there is less dependency between the variation of density and size of a defect and variations of noise density and distribution. Experimental images from eddy current, ultrasonic and radiography techniques are investigated. It is shown that the new approach reduces the noise and drift, leading to a better detection of defects. 相似文献
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Yuri V. Batygin Sergey F. Golovashchenko Andrey V. Gnatov 《Journal of Materials Processing Technology》2013,213(3):444-452
The paper is dedicated to the study of pulsed electromagnetic attraction processes which can deform ferromagnetic sheet metal materials such as low carbon steels using low frequency discharges. The analytical model based upon the solution of Maxwell equations explains that magnetic forces are prevailing over the Lorentz forces for low frequency discharges. For electromagnetic forming (EMF) processes employing ferromagnetic sheet metal blanks of low electrical conductivity with relatively slow electric discharges, the magnetic forces should be taken into account in order to achieve a correct representation of electromagnetic forces applied to the blank. An engineering estimate on the size of magneto-static forces and Lorentz-forces is the outcome of the analytical work. In addition to analytical work and validation of the proposed engineering estimate of attracting forces, a single turn coil is introduced which is more robust than previous designs with multiple frequencies and interrupted discharges. The simplified setup only requires a rather slow single frequency low voltage electric discharge which allows for using cheaper and longer life capacitors, substantially reduces the safety implications and also extends the life of the coil insulation. 相似文献
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Magnetic Barkhausen noise ( MBN) is a phenomenon of electromagnetic energy due to the movement of magnetic domain walls inside ferromagnetic materials when they are locally magnetized by an alternating magnetic fields. According to Faraday's law of electromagnetic induction, the noise can be received by the coil attached to the surface of the material being magnetized and the noise carries the message of the characteristics of the material such as stresses, hardness, phase content, etc. Based on the characteristic of the noise, researching about the relationship between the residual stress in the welding assembly and the noise are carried out. Furthermore, data process is performed by RMS (Root Mean Square) equation and Power Spectrum analysis. 相似文献
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Design and modelling of a passive wireless pressure sensor 总被引:2,自引:0,他引:2
J. Zhai 《CIRP Annals》2010,59(1):187-190
This investigation is concerned with the design and modelling of a passive wireless pressure sensor to detect blood pressure inside an abdominal aortic aneurysm sac after endovascular repair of the aneurysm. The sensor consists of a coil and a capacitor to form an inductor-capacitor (LC) resonant circuit which oscillates electrically at its resonant frequency. This miniature sensor has a size of 6 mm × 6 mm × 1 mm and can be fabricated by microelectromechanical system (MEMS) technology. By activating the sensor with an electromagnetic field, aneurysm sac pressure information can be acquired. The properties and behaviour of this sensor based on computer simulation are also presented in this paper. 相似文献
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针对转子不平衡振动信号非平稳性并伴随较强环境噪声的特点,提出一种基于快速独立分量分析(FastICA)和改进希尔伯特-黄变换相结合的故障特征提取方法。该方法采用FastICA法去除环境噪声等因素对于故障特征提取精度的影响,再利用自适应白噪声总体平均模态分解方法将故障信号分解为一系列固有模态函数(IMF),并采用基于相似性评估的虚假IMF选择算法将与故障信息无关的虚假IMF分量剔除,从而保证故障信息提取的准确性和有效性。通过仿真分析证明了所提方法的有效性,并且实际试验表明:该方法可有效提取转子不平衡信号的故障特征,为该类故障的诊断提供了一种切实可行的方法。 相似文献