Messaoudi Noureddine, Bekka Raïs El'hadi, Ravier Philippe, Harba Rachid
Université de Boumerdès, Faculty of Sciences, Department of Physics, 35000 Boumerdès, Algeria; Université Ferhat Abbes de Sétif 1, Faculty of Technology, Department of Electronics, LIS Laboratory, 19000 Sétif, Algeria.
Université Ferhat Abbes de Sétif 1, Faculty of Technology, Department of Electronics, LIS Laboratory, 19000 Sétif, Algeria.
J Electromyogr Kinesiol. 2017 Feb;32:70-82. doi: 10.1016/j.jelekin.2016.12.006. Epub 2016 Dec 25.
The purpose of this paper was to evaluate the effects of the longitudinal single differential (LSD), the longitudinal double differential (LDD) and the normal double differential (NDD) spatial filters, the electrode shape, the inter-electrode distance (IED) on non-Gaussianity and non-linearity levels of simulated surface EMG (sEMG) signals when the maximum voluntary contraction (MVC) varied from 10% to 100% by a step of 10%. The effects of recruitment range thresholds (RR), the firing rate (FR) strategy and the peak firing rate (PFR) of motor units were also considered. A cylindrical multilayer model of the volume conductor and a model of motor unit (MU) recruitment and firing rate were used to simulate sEMG signals in a pool of 120 MUs for 5s. Firstly, the stationarity of sEMG signals was tested by the runs, the reverse arrangements (RA) and the modified reverse arrangements (MRA) tests. Then the non-Gaussianity was characterised with bicoherence and kurtosis, and non-linearity levels was evaluated with linearity test. The kurtosis analysis showed that the sEMG signals detected by the LSD filter were the most Gaussian and those detected by the NDD filter were the least Gaussian. In addition, the sEMG signals detected by the LSD filter were the most linear. For a given filter, the sEMG signals detected by using rectangular electrodes were more Gaussian and more linear than that detected with circular electrodes. Moreover, the sEMG signals are less non-Gaussian and more linear with reverse onion-skin firing rate strategy than those with onion-skin strategy. The levels of sEMG signal Gaussianity and linearity increased with the increase of the IED, RR and PFR.
本文的目的是评估纵向单差分（LSD）、纵向双差分（LDD）和常规双差分（NDD）空间滤波器、电极形状、电极间距（IED）对模拟表面肌电图（sEMG）信号非高斯性和非线性水平的影响，此时最大自主收缩（MVC）以10%的步长从10%变化到100%。还考虑了募集范围阈值（RR）、放电率（FR）策略和运动单位的峰值放电率（PFR）的影响。使用体积导体的圆柱形多层模型以及运动单位（MU）募集和放电率模型，在120个运动单位的集合中模拟5秒的sEMG信号。首先，通过游程检验、反向排列（RA）检验和改进的反向排列（MRA）检验来测试sEMG信号的平稳性。然后用双相干性和峰度来表征非高斯性，并用线性检验来评估非线性水平。峰度分析表明，由LSD滤波器检测到的sEMG信号最接近高斯分布，而由NDD滤波器检测到的信号高斯性最差。此外，由LSD滤波器检测到的sEMG信号线性度最高。对于给定的滤波器，使用矩形电极检测到的sEMG信号比使用圆形电极检测到的信号更接近高斯分布且线性度更高。此外，与采用洋葱皮放电率策略相比，采用反向洋葱皮放电率策略时，sEMG信号的非高斯性更低且线性度更高。sEMG信号的高斯性和线性水平随着电极间距、募集范围阈值和峰值放电率的增加而增加。
