共查询到17条相似文献,搜索用时 265 毫秒
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基于信息融合的电解加工间隙检测 总被引:2,自引:0,他引:2
目前,在电解加工中还没有有效的加工间隙在线检测方法[1]。本文通过采集真实电解加工中阴极表面上来自电解液的平行于机床主轴的力和加工电流,利用小波变换对采集的信号进行处理,提取趋势项。结果发现:随着间隙减小力和加工电流都增大,可以据此间接实现间隙的测量。用力和加工电流经过小波变换提取的趋势项进行信息融合来更好地反映间隙,将它用于方坯加工叶片时采用的全程控制。用神经网络建立数显进给位置与力和电流融合信号之间的非线性映射,使它作为标准曲线以对间隙进行自动的全程控制。 相似文献
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主要介绍了3种基于小波包分解的以不同方式进行提取刀具磨损振动信号特征向量的方法。刀具振动信号通过小波包分解后重构成不同频段的信号系数。在此基础上,首先提取各个频段能量基于总能量比值的特征向量;其次对其进行功率谱分析,提取特定频段幅值的特征向量;最后,利用奇异值分解将不同频段的信号映射到正交子空间中,从中选取信号的奇异值作为特征向量。最终将得到的特征向量组合成一个特征向量输入支持向量机中进行刀具磨损识别。 相似文献
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无刷直流电机转速的闭环控制系统中同时存在传感器噪声等高频信号和指令、干扰等低频信号,会导致匀速转动过程中发生速度波动,而同时减少这些不确定因素的影响非常困难。针对此问题,提出了一种模糊自整定的小波多分辨PID(MRPID)控制方法,用于无刷直流电机的转速控制。通过离散小波变换将速度偏差信号进行分解,得到不同频率控制分量;利用模糊控制实现各分量参数的在线整定。与模糊PID控制方法进行对比,在不同工况下进行仿真及实验,结果表明,所提方法能够更好地处理含噪信号,并且具有响应快、抗干扰能力强的优点。 相似文献
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《Mechanical Systems and Signal Processing》2007,21(2):688-705
This paper presents a novel method for fault diagnosis based on an improved wavelet package transform (IWPT), a distance evaluation technique and the support vector machines (SVMs) ensemble. The method consists of three stages. Firstly, with investigating the feature of impact fault in vibration signals, a biorthogonal wavelet with impact property is constructed via lifting scheme, and the IWPT is carried out to extract salient frequency-band features from raw vibration signals. Then, the faulty features can be detected by envelope spectrum analysis of wavelet package coefficients of the most salient frequency band. Secondly, with the distance evaluation technique, the optimal features are selected from the statistical characteristics of raw signals and wavelet package coefficients, and the energy characteristics of decomposition frequency band. Finally, the optimal features are input into the SVMs ensemble with AdaBoost algorithm to identify the different abnormal cases. The proposed method is applied to the fault diagnosis of rolling element bearings, and testing results show that the SVMs ensemble can reliably separate different fault conditions and identify the severity of incipient faults, which has a better classification performance compared to the single SVMs. 相似文献
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用Haar小波基函数生成三角形及梯形隶属函数,建立基于小波分析的模糊控制器,利用小波在时域和频域同时具有良好的局部化特性,根据系统输出误差在线调整隶属函数的形状,使模糊控制器得到优化并具有强大的自适应能力.仿真结果表明这种控制器比常规的PID或PD控制器具有更优的动、静态性能和抗干扰能力,而且有很强的跟踪能力. 相似文献
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Murali Sundaram Amy Drexelius Abishek B. Kamaraj 《Machining Science and Technology》2019,23(2):232-248
Electrochemical additive manufacturing (ECAM) is achieved by localized electrochemical deposition (LECD). The ECAM can print metal parts directly from computer models at macro-, micro- and nanoscales at room temperature without any thermal defects. This study aims to (1) simulate the effects of the interelectrode gap (IEG) on cation concentration and current density in the deposition zone during ECAM; (2) quantify the localization of the desired deposit, as well as unintended plating when using various IEGs, and (3) determine the rate of deposition for different IEGs. Current density patterns under stationary and moving anode conditions were analyzed to calculate deposition rate and the corresponding time to fill an IEG. Experiments were performed to monitor current density and time to fill IEG during deposition and compared with the simulation results. Studying the migration behavior of cations and the current density allowed deposition height to be predicted and the extent of plating to be quantified, using a distortion factor. It was found that for the ECAM conditions used in this study, smaller IEGs (<10?µm) result in lower rates of deposition due to the cation depletion, while larger IEGs (50?µm) result in an increase in plating tendency due to cation migration. 相似文献
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基于小波包变换的滚动轴承故障诊断 总被引:1,自引:0,他引:1
针对故障轴承振动信号能量集中与调制的特点,提出了一种基于小波包能量法与Hilbert变换的滚动轴承故障诊断方法。使用小波包变换对振动信号进行分解、重构及能量计算,并应用Hilbert变换对能量集中频段的重构信号进行解调和频谱分析,提取故障特征频率。同时针对诊断过程中故障特征参数依靠人工计算的问题,提出故障特征参数自动提取方法。实际的滚动轴承实验数据的处理和分析结果表明,该诊断方法能够准确、快速地识别滚动轴承表面损伤的故障模式。 相似文献