共查询到19条相似文献,搜索用时 233 毫秒
1.
齿轮箱是复杂的动力学系统,其故障信号通常呈现出非平稳和非线性特征,因此齿轮箱故障信号的特征提取是一个难题。去趋势波动分析(Detrended Fluctuation Analysis,DFA)可以用来分析非平稳非线性数据,得到的标度曲线可以用来刻画复杂系统的动力学行为。然而原始序列的标度曲线通常具有复杂的形状,所以从原始序列的标度曲线提取故障特征具有一定的困难。为了解决这个问题,对齿轮箱故障数据增量序列的动力学特性进行了研究,结果证明增量序列的幅值分量主要携带数据的非线性特征,然后提出了基于时间序列幅值分量标度特性的齿轮箱故障特征提取方法。该方法首先计算原始序列的增量序列,获得增量序列的幅值分量,然后利用DFA方法计算幅值分量的标度曲线,最后提取标度曲线的左端点和转折点的波动参数作为故障特征进行故障诊断。利用实测数据对所提出方法的性能进行了验证,结果表明,该方法对噪声干扰具有较好的鲁棒性,可以有效地对齿轮箱故障进行诊断,与传统的时域参数方法相比具有明显的优势。 相似文献
2.
《中国工程机械学报》2015,(3)
为克服混凝土泵送系统参数时变和不确定性因素以及负载的突变性,提出了发动机转速和液压泵排量双参数控制策略,提高了控制系统响应的快速性和稳定性.通过现场试验总结出混凝土泵车泵送系统的负载具有周期性和突变性的特点,通过油耗试验发现发动机转速波动对燃油消耗的影响严重.基于系统的动力学方程设计了压差感应换向双参数控制系统,实现了对混凝土泵车发动机转速和液压泵排量的双闭环控制,提高了系统的动态响应速度和稳态控制精度.改进前后的对比试验表明:双参数控制策略相比于传统的单参数分段控制策略具有较优的控制性能和燃油经济性,发动机的转速波动可降低50r·min-1,换向的响应时间和整机效率可提高7%,平均油耗降低5%. 相似文献
3.
提高子系统激励源的区分度对准确识别出主振动源有重要意义,而去趋势波动分析法(DFA)被认为是一种有效的方法。为更准确地提高子系统激励源的区分度,本文将DFA法与极值增量序列结合,提出了超阶分析新方法。首先建立了两相关子系统输入单输出系统模型,然后介绍了DFA法和超阶分析法的相关理论,接着分别用这两个方法分析了实验所得的相关信号的区分度,最后将所得的差异指数进行比较。结果表明,对于完全相关信号,超阶分析方法所得的差异指数远远小于DFA得到的,准确识别出信号差异仅为0.08%;对于部分相关信号,超阶分析法所得的差异指数比DFA得到的大了36.5%,更能提高相关信号的区分度,从而验证了超阶分析方法是一种区分相关子系统激励源的优秀方法。 相似文献
4.
基于非平稳时间序列双标度指数特征的齿轮箱故障诊断 总被引:8,自引:0,他引:8
齿轮箱振动信号是含噪的多分量非平稳信号,故障模式相近的复杂齿轮箱振动信号的分类是齿轮箱故障诊断的难点。采用去趋势波动分析(Detrended fluctuation analysis,DFA)方法分析齿轮箱振动信号的标度行为,随着时间尺度的增大,标度指数会突然发生改变,形成双标度指数特征,由双标度指数构成的二维矢量具有明确的物理意义,可以作为表征时间序列内部动力学机制的特征参数。提出一种基于非平稳时间序列双标度指数特征的齿轮箱故障诊断方法,对正常状态和含有轻度磨损、中度磨损和断齿故障的齿轮箱故障诊断的结果表明,提出的方法成功地解决了故障模式相近的复杂齿轮箱振动信号的分类问题,很好地克服了傅里叶变换、小波变换和基于单标度指数的方法存在的缺陷,为齿轮箱的故障诊断提供了一种新的方法。 相似文献
5.
提出了一种新的嵌入式时栅角位移传感器的自标定方法,以提高这类传感器在没有高精度母仪标定以及参数和工作环境发生变化时的测量精度。介绍了嵌入式时栅的特点,提出了利用两个间隔一定角度离散测头之间的误差规律变换来实现自标定的方法。设计了动态自标定系统,采用卡尔曼动态滤波算法来降低动态标定过程中传感器自身稳定性波动和环境干扰的影响。为了寻求最优参数以保证标定精度,提出了残差的控制算法。最后,运用设计的自标定系统对传感器进行了标定实验,并与以往母仪标定方法进行了对比。实验结果表明,传感器的误差从标定前±20″降低到±2.4″,标定参数与实际传感器误差成分相吻合,标定精度与以往母仪标定的精度基本相同,满足时栅传感器的标定要求。 相似文献
6.
针对工作任务复杂或环境多变,且对机械臂精度要求较高的工业生产需求等问题,基于运动学参数标定方法进行了机械臂的误差分析与Matlab仿真。介绍了定位精度以及定位误差的来源,针对机械臂运动学标定的方法步骤,采用矩阵法对运动学参数标定误差模型进行了建模分析,推导出了运动学参数误差模型的通用形式,并添加一个微小的增量进行了误差补偿;采用Matlab对机械臂运动学参数误差模型进行了仿真分析,验证了所建立的误差模型的正确性。研究结果表明:基于运动学参数标定方法的机械臂误差分析能很好地提高机械臂的精度,使机械臂能够准确完成预期的位姿要求,对于进一步提高机械臂的精度有较好的指导作用。 相似文献
7.
8.
9.
分析了一类智能交通系统(intelligent transportation system,ITS)用挠性陀螺的标度因数与输入角速率和环境温度之间的非线性关系,重点研究了不同环境温度下标度因数的变化规律及其标定问题.充分考虑了输入角速率与环境温度对挠性陀螺标度因数的影响,首次提出了一种基于环境温度的挠性陀螺多速率精确标定与补偿方法,建立了高阶、高次、非线性的标度因数拟合模型.实验研究结果表明,相对现有技术,提出的模型拟合精度较高且应用简便,能够有效地降低温度对标度因数的影响,提高挠性陀螺的温度适应性. 相似文献
10.
11.
YANG Lihong LIU Chengliang ZHA Xuanfang 《机械工程学报(英文版)》2008,21(1):53-56
In order to obtain the accurate sonic conductance of solenoid valves, the polytropic exponent is used in the data processing of the discharge method for measuring the flow rate characteristics of pneumatic components. Three data processing principles are first introduced, and then the discharge pressure data obtained from the measured solenoid valve are processed to obtain the sonic conductance with three methods: the partial polytropic exponent method, the complete polytropic exponent method and the adiabatic method. By comparison of the obtained results it indicates that the complete polytropic exponent method is the most accurate. However, the partial polytropic exponent method is of a high applicable value, because it is easy and simple to measure and the obtained results are relatively accurate. 相似文献
12.
This study examined scaling properties of an increment series from rotating machinery. Moreover, two fluctuation parameters for the smallest and largest time scales of a scaling range served as a pair of fluctuation parameters to describe system conditions. Therefore, an interesting phenomenon is observed: the data points, each representing a pair of fluctuation parameters, for fault conditions almost form a straight line, while those for normal clearly depart from the straight line. To describe the phenomenon, a novel concept termed the diagnostic line was introduced. Subsequently, properties of the diagnostic line were carefully investigated theoretically and numerically. Consequently, a decisive role of noise in forming the diagnostic line was determined. Accordingly, this study develops a novel criterion for condition monitoring of rotating machinery. 相似文献
13.
14.
15.
16.
17.
E.P. de Moura A.P. Vieira M.A.S. Irmão A.A. Silva 《Mechanical Systems and Signal Processing》2009,23(3):682-689
Aiming at fault diagnosis, we study vibration signals obtained from gearboxes under various conditions. We consider normal gearboxes, gearboxes containing scratched gears, and gearboxes containing toothless gears, both unloaded and under load, with several rotation frequencies. By applying detrended-fluctuation analysis (DFA), a mathematical tool introduced to study fractal properties of time series, we are able to distinguish the signals with respect to their working conditions. For each signal, DFA involves performing a linear fit to the data inside intervals of a certain size, and evaluating the corresponding fluctuations detrended by the local fit. Repeating this procedure for many interval sizes yields a curve of the average fluctuation as a function of size. From the curves, we define vectors whose components correspond to the average fluctuation associated with suitably chosen interval sizes. We finally apply principal component analysis to the set of all vectors, obtaining very good clustering of the transformed vectors according to the different working conditions, with a performance comparable to that obtained from Fourier analysis, especially for gears working under load. 相似文献
18.
Double-suction centrifugal pumps have been applied extensively in many areas,and the significance of pressure fluctuations inside these pumps with large power is becoming increasingly important.In this study,a double-suction centrifugal pump with a high-demand for vibration and noise was redesigned by increasing the flow uniformity at the impeller discharge,implemented by combinations of more than two parameters.First,increasing the number of the impeller blades was intended to enhance the bounding effect that the blades imposed on the fluid.Subsequently,increasing the radial gap between the impeller and volute was applied to reduce the rotor-stator interaction.Finally,the staggered arrangement was optimized to weaken the efficacy of the interference superposition.Based on numerical simulation,the steady and unsteady characteristics of the pump models were calculated.From the fluctuation analysis in the frequency domain,the dimensionless pressure fluctuation amplitude at the blade passing frequency and its harmonics,located on the monitoring points in the redesigned pumps(both with larger radial gap)are reduced a lot.Further,in the volute of the model with new impellers staggered at 12°,the average value for the dimensionless pressure fluctuation amplitude decreases to 6% of that in prototype pump.The dimensionless rootmean-square pressure contour on the mid-span of the impeller tends to be more uniform in the redesigned models(both with larger radial gap);similarly,the pressure contour on the mid-section of the volute presents good uniformity in these models,which in turn demonstrating a reduction in the pressure fluctuation intensity.The results reveal the mechanism of pressure fluctuation reduction in a double-suction centrifugal pump,and the results of this study could provide a reference for pressure fluctuation reduction and vibration performance reinforcement of doublesuction centrifugal pumps and other pumps. 相似文献
19.
《流体机械》2013,(10)
介绍了某项目用泵的2个需求工况点,应用欧拉扬程公式计算单叶轮设计时的叶轮外径,并计算圆盘摩擦损失预估泵效率,初步分析表明单叶轮设计不仅效率极低,而且也无法满足2个设计目标。针对比开发了一种双叶轮双出口组合的新型结构型式,介绍了其工作原理。其中主要过流部件采用模型换算法,应用面积比法计算正导叶外接的首级叶轮蜗壳的第Ⅷ断面面积。根据模型试验数据换算得到该多目标泵的外特性曲线并用现代CFD技术进行了数值仿真。发现扬程—流量曲线的模型试验数据与仿真结果曲线一致,满足2个工况点的目标需求。与模型换算数据相比,数值仿真得到的数据最高效率点向大流量方向偏移,这是由于第一级蜗壳是以正导叶为基础采用面积比法设计、过流断面大导致的。 相似文献