Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
University of Science and Technology of China, Hefei 230026, China.
Sensors (Basel). 2023 May 29;23(11):5182. doi: 10.3390/s23115182.
Power line interference (PLI) is a major source of noise in sEMG signals. As the bandwidth of PLI overlaps with the sEMG signals, it can easily affect the interpretation of the signal. The processing methods used in the literature are mostly notch filtering and spectral interpolation. However, it is difficult for the former to reconcile the contradiction between completely filtering and avoiding signal distortion, while the latter performs poorly in the case of a time-varying PLI. To solve these, a novel synchrosqueezed-wavelet-transform (SWT)-based PLI filter is proposed. The local SWT was developed to reduce the computation cost while maintaining the frequency resolution. A ridge location method based on an adaptive threshold is presented. In addition, two ridge extraction methods (REMs) are proposed to fit different application requirements. Parameters were optimized before further study. Notch filtering, spectral interpolation, and the proposed filter were evaluated on the simulated signals and real signals. The output signal-to-noise ratio (SNR) ranges of the proposed filter with two different REMs are 18.53-24.57 and 18.57-26.92. Both the quantitative index and the time-frequency spectrum diagram show that the performance of the proposed filter is significantly better than that of the other filters.
电力线干扰（PLI）是 sEMG 信号噪声的主要来源。由于 PLI 的带宽与 sEMG 信号重叠，因此很容易影响信号的解释。文献中使用的处理方法主要是陷波滤波和频谱插值。然而，前者很难调和完全滤波和避免信号失真之间的矛盾，而后者在时变 PLI 的情况下表现不佳。为了解决这些问题，提出了一种基于同步挤压小波变换（SWT）的 PLI 滤波器。局部 SWT 的开发降低了计算成本，同时保持了频率分辨率。提出了一种基于自适应阈值的脊线定位方法。此外，还提出了两种脊提取方法（REMs）以适应不同的应用要求。在进一步研究之前，对参数进行了优化。在模拟信号和真实信号上评估了陷波滤波、频谱插值和所提出的滤波器。两种不同 REM 下的滤波器的输出信噪比（SNR）范围分别为 18.53-24.57 和 18.57-26.92。无论是定量指标还是时频谱图都表明，所提出的滤波器的性能明显优于其他滤波器。
