离散振动信号分形盒维数的改进算法和应用

摘要

提出了振动信号的双尺度性概念，分析了离散信号盒维数一般计算方法的不足，推导出了确定周期或准周期振动信号无标度区的经验公式，给出了盒维数的改进算法。验证结果表明：盒维数的改进算法简单可靠。对汽轮机组轴瓦松动故障的分析说明：盒维数可以作为识别振动信号复杂程度的一个新的无量纲指标。%Fractal Box Dimension(BD), which can represent self-similarity and complexity of nonstationary vibration signal, provides a new tool for fault diagnosis of mechanical equipment. In this paper, we first analyze the shortcoming of conventional method for calculating BD of discrete vibration signal. Then we propose an improved algorithm of BD which include two key technologies. First, square box is replaced with rectangle box due to the bi-scale characteristic of vibration signal. Second, an empirical formula is derived for choosing scale-invariant region of periodic or quasi-periodic signals. Experimental results show that the improved algorithm of BD is simple and effective. As a successful application, BD is used to detect looseness fault in bearing bushing of turbo-generator set.