低成本sEMG采集电路的设计及自适应EEMD降噪研究

Design of low⁃cost sEMG acquisition circuit and research onits adaptive EEMD noise reduction

表面肌电信号(sEMG)是人体肌肉在收缩过程中产生的电信号,具有独特的输出特性。由于肌电信号的振幅小,易受噪声影响,必须设计合适的电路对肌电信号进行采集和放大。为此,设计了由低成本运放组成的多通道肌电信号采集电路,并成功采集了翻腕动作下的sEMG。采用一种基于归一化指标寻优的自适应总体经验模态分解(EEMD)降噪方法,对所采集的翻腕sEMG进行降噪处理。分析了噪声所处分量,确定了信号重构的分量数,设计了归一化降噪指标,得到了最佳的降噪循环次数和降噪结果,并与经验模态分解(EMD)和小波变换降噪方法进行比较,实验结果表明,所设计的算法具有更好的降噪性能,能够配合所设计的电路实现sEMG的高精度采集。

Surface electromyography(sEMG)is the electrical signal generated by human muscle during contraction.It has unique output characteristics.The EMG signals are prone to being affected by noise because of its small amplitude,so it is necessary to design a suitable circuit to acquire and amplify the EMG signals.Therefore,a multi⁃channel EMG signal acquisition circuit composed of a low⁃cost operational amplifier is designed,and the sEMG under the roll⁃over action is successfully acquired.An adaptive ensemble empirical mode decomposition(EEMD)noise reduction method based on normalized index optimization is adopted to implement denoising for the collected sEMG signals.The noise components are analyzed,the number of signal reconstruction components is determined,and the normalized noise indexes are designed,so as to obtain the times of optimum noise reduction cycle and noise reduction result.The experimental results show that,in comparison with the empirical mode decomposition(EMD)method and wavelet transformation noise reduction method,the designed algorithm has better performance of noise reduction,and can achieve high⁃accuracy acquisition in cooperation with the designed circuit.