基于DWT和DFT的动平衡机不平衡量提取原理及实现

Principle and Implementation of Unbalanced Signal Extraction from a Dynamic Balancing Machine Based on DWT & DFT

在超微型转子(质量小于10g)动平衡机中,主要干扰分为同频干扰、高频干扰和低频干扰。针对测试环境中不平衡量信号的特点,利用离散小波变换对信号进行3层分解,提取有用的低频信号、接着进行频谱分析,在频域提取不平衡量所对应的幅度和相位,有效地滤除了信号中混杂的低频及高频干扰,所测得的误差大大减小,不平衡量幅度测试精度达4μm,相角小于2°,为保证平衡机系统一次去重90％以上提供了前提。所用算法在数字信号处理器上实现。

The main interferences are co-frequency, high- frequency and low-frequency interferences. According to the characteristics of unbalance signals, useful signal is extracted by decomposing the signal to the 3rd layer using discrete wavelet transform (DWT). In frequency domain, the amplitude and phase of unbalanced signals are extracted on the basis of discrete Fourier transform (DFT), with high- frequency and low-frequency interferences filtered out effectively from the desired signal, so error is reduced greatly. With the measurement accuracy of the amplitude of unbalance less than 4 um and the phase less than 2?, the unbalance mass at the whole system of the balancing machine can be reduced by over 90% once. All the algorithms are implemented by using a digital signal processor.