连续小波变换在肢体表面肌电信号反射响应中的应用

中文字数:9075,中文页数:14  英文字数:6742页数:24

Abstract
Objective: This is the first reported use of the continuous wavelet transform (CWT) of the surface EMG (sEMG) to extract the reflex response to muscle stretch. We used a modulus-based method to estimate instantaneous amplitude-envelopes from ridges of the CWT (referred in this work as sEMG intensity) to extract the dynamic reflex response from sEMG. We tested the method on tendon reflexes where excellent temporal resolution is required to identify the different latency components, and on the tonic stretch reflex (tonic SR) response to an ongoing perturbation that characteristically has a low signal to noise ratio.
Methods: Eight subjects without neurological impairment were subjected to a series of archilles tendon taps and a 2 min continuous perturbation of the ankle using a pseudo-sinusoidal stretch profile containing frequencies from 0.1 to 8.0 Hz. The tendon reflexes were assessed in the soleus muscle at 10% of MVC and the tonic SR in timbales anterior while the muscle was relaxed, at 5 and 10% of maximal voluntary contraction. Root mean square (RMS) and wavelet ridge extraction was applied to the sEMG signal to extract sEMG amplitudes (RMS) and intensities for all reflexes. To obtain the tonic SR, these estimates and those from the sEMG-RMS were subsequently cross-correlated with the perturbation record to yield 2 sets of estimates of reflex gain and coherence for comparison.

摘  要
目的：本文利用连续小波变换提取肢体伸缩反射响应的肌电信号。基于模量方法，估计连续小波变换（本文涉及的肌电信号强度）提取动态反射响应的肌电信号峰值的瞬时幅度线。用这种方法测试腱的反射，通过腱瞬时分解不同的未知分量。也可以用这种方法测试，运动中特有的增强的伸缩反射微小扰动信号的噪音比率。
方法：研究神经系统未损害的8个研究对象，测试一系列主要的几个腱和一个用含有频率0.1～0.8Hz的拟典型正弦波形变化延伸变量曲线表示2分钟连续微扰的踝关节。当处于放松状态的肌肉以MVC的5%和10%最大限度自由伸缩时，增强的伸缩反射和在MVC的10%处的反射是估定值。利用求取表面肌电信号的均方根值和对小波峰值开方的方法提取表面肌电信号所有反射的幅度和强度。利用增强的伸缩反射估计值和表面肌电信号的均方根值的交互作用产生2种获取反射和对比连贯性的估计方法。
结果：肌电信号的强度与快速任意伸缩的扭转相关显著。对于少量的腱，这种方法分解了肌肉1、肌肉2和肌肉3的响应分量，这些分量是精确的潜优值，更大可能是对均方根衍生的估计值的完全重建。从静止状态和收缩状态的肌肉上提取的增强伸缩反射的小波估计值的连贯性比均方根估计值显著地高。利用肌电信号强度或肌电信号均方根获得的反射表明，微扰频率和干扰信号收缩程度有相似的特性曲线。均分不同对象的肌电信号获得的估计值显示，平均值的方差比已校正的肌电信号的估计值下降显著。
结论：小波峰值提取法提供了一种有效的方法，通过不依赖电极实测电压的离散幅度估计肌电信号的反射值。它更有利于利用不需要统一最大限度伸缩尺度的离散频率尺度对比物体间响应。

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