低速重载机械早期故障稀疏特征提取的研究

发布时间：2019-01-18 19:30

【摘要】：本课题的研究来源于国家自然科学基金《低速重载机械早期故障稀疏特征识别的研究》。低速重载机械是冶金企业的重要设备（如转炉耳轴、高炉布料器、钢包回转台等），低速重载机械早期故障诊断技术是目前机械故障诊断领域的研究热点和难点，探索低速重载机械早期故障诊断的关键技术，对于保障设备的安全稳定运行、避免突发的重大设备事故和人身安全事故具有重要的理论意义和应用价值。论文针对低速重载机械的振动信号特点，深入研究了低速重载机械早期故障信号的提取难题和设备安全运行时间预测的难题。针对低速重载机械单一故障特征下的微弱冲击信号提取问题，论文首先提出了一种自适应形态梯度提升方法。通过形态提升，将微弱脉冲信号放大，再利用形态梯度滤波滤掉信号中的低频成份，保留信号中的脉冲信号。该方法具有计算效率高的优点，并且对于一定信噪比下的微弱故障冲击信号，具有较高的精度。同时，针对低速重载机械单一故障特征下的微弱冲击信号提取问题，论文提出了一种基于包络的正交匹配追踪方法。通过原子包络和振动信号包络的匹配搜索，确定原子的位移因子和尺度因子，进一步搜索确定频率因子和相位因子，最终达到提取微弱冲击信号的目的。原子时频因子的分开搜索，使得卷积和FFT能有效应用在搜索过程中，提高了原子搜索效率。该方法能提取低信噪比下的微弱故障冲击信号，并且具有高精度的优势，但是在计算效率上不具有自适应形态梯度提升方法快捷的优势。针对低速重载机械多源故障特征下的微弱冲击信号提取问题，论文提出了一种基于相干累积量的分段正交匹配追踪方法。采用框架思想的分段正交匹配追踪方法具有提取混叠信号的优势，弥补了正交匹配追踪方法在提取多源故障混叠信号中的不足。通过深入探讨多源早期故障信号过完备原子库中内置相干累积量和外置相干累积量的关系，可以快速确定原子的位移因子和频率因子，，为分段正交匹配追踪方法提供最优的原子选取策略。该方法缩小了分段正交匹配追踪方法中子框架的原子规模，可以快捷、稀疏、精确地表示多源故障的混叠冲击信号。针对裂纹故障中裂纹宽度估算的问题，论文提出了一种邻域正交匹配追踪方法。讨论了裂纹、点蚀等早期故障时信号特有的双冲击信号特征，并根据双冲击信号合理构建原子的邻域集合，将双冲击信号在其邻域中进行表示，可以准确提取出裂纹故障的双冲击信号。再根据当前的采样频率、转速，以及获取的双冲击信号时间间隔等信息估算出裂纹的宽度。该方法可以有效识别裂纹故障的程度，对设备安全运行时间预测具有重要的指导意义。
[Abstract]:The research of this topic comes from the National Natural Science Foundation of China, Research on early Fault sparse feature recognition of low Speed heavy load Machinery. Low speed heavy duty machinery is an important equipment in metallurgical enterprises (such as converter ear shaft, blast furnace feeder, ladle rotary table, etc.). The early fault diagnosis technology of low speed heavy load machinery is a hot and difficult point in the field of machinery fault diagnosis at present. It is of great theoretical significance and practical value to explore the key techniques of early fault diagnosis for low speed heavy duty machinery to ensure the safe and stable operation of equipment and to avoid sudden major equipment accidents and personal safety accidents. According to the characteristics of vibration signal of low speed and heavy load machinery, the problem of early fault signal extraction and safe operation time prediction of low speed and heavy load machinery are studied in this paper. Aiming at the problem of weak impulse signal extraction under the single fault feature of low-speed and heavy-duty machinery, an adaptive morphological gradient lifting method is proposed in this paper. The weak pulse signal is amplified and the low frequency component of the signal is filtered by morphological gradient filter to retain the pulse signal. This method has the advantages of high computational efficiency and high accuracy for weak fault impulse signals with a certain SNR. At the same time, aiming at the weak impulse signal extraction problem under the single fault feature of low-speed and heavy-duty machinery, an envelope based orthogonal matching tracking method is proposed in this paper. By matching the envelope of atomic envelope and vibration signal, the displacement factor and scale factor of atom are determined, the frequency factor and phase factor are further searched and the weak impulse signal is extracted. With the separation of atomic time-frequency factors, convolution and FFT can be effectively applied in the search process, and the efficiency of atomic search is improved. This method can extract weak fault impulse signals with low signal-to-noise ratio (SNR), and has the advantage of high accuracy, but it does not have the advantage of fast adaptive morphological gradient lifting method in computational efficiency. A piecewise orthogonal matching tracking method based on coherent cumulants is proposed to extract weak impulse signals from low speed and heavy load machinery with multi-source fault characteristics. The frame based piecewise orthogonal matching tracking method has the advantage of extracting aliasing signals, which makes up for the deficiency of orthogonal matching tracing method in extracting multi-source fault aliasing signals. By deeply discussing the relationship between the built-in coherent cumulant and the external coherent cumulant in the over-complete atomic library of multi-source early fault signals, the displacement factor and frequency factor of the atom can be determined quickly. It provides an optimal atomic selection strategy for piecewise orthogonal matching tracing. This method reduces the atomic size of the neutron frame in the piecewise orthogonal matching tracing method and can quickly, sparsely and accurately represent the aliasing shock signals of multi-source faults. Aiming at the problem of crack width estimation in crack fault, a neighborhood orthogonal matching tracing method is proposed in this paper. In this paper, we discuss the characteristic of double impulse signal in the early faults such as crack and pitting. According to the double impulse signal, we construct the neighborhood set of atoms reasonably, and express the double impulse signal in its neighborhood. The double impulse signal of crack fault can be accurately extracted. The width of the crack is estimated according to the current sampling frequency, rotational speed and the time interval of the obtained double impulse signals. This method can effectively identify the degree of crack failure, and has important guiding significance for predicting the safe operation time of equipment.
【学位授予单位】：武汉科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN911.7

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