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Journal of ZheJiang University (Engineering Science)  2024, Vol. 58 Issue (11): 2208-2218    DOI: 10.3785/j.issn.1008-973X.2024.11.002
    
Recognition method of surface electromyographic signal based on two-branch network
Wanliang WANG(),Jie PAN,Zheng WANG,Jiayu PAN
College of Computer Science and Technology, Zhejiang University of Technology, Hangzhou 310023, China
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Abstract  

An enhanced two-dimensional feature based two-branch network (ETDTBN) was proposed aiming at the problems of insufficient detailed information extraction and difficulty in distinguishing similar gestures in surface electromyogram (sEMG) gesture recognition. Discrete features were converted into two-dimensional feature maps by the proposed enhanced two-dimensional method. Then a multi-layer convolutional neural network (ML-CNN) was used to extract the spatial features, while a bidirectional gated recurrent unit (Bi-GRU) was used to extract the temporal features from the original signal. A self-adaptive feature fusion mechanism was introduced to fuse different branches, strengthen useful features and weaken useless features in order to improve the accuracy of sEMG recognition by considering that different features had different degrees of influence on the network. Experiments were used to train and test the ETDTBN in two scenarios of electrode displacement and different subjects comparing with mainstream sEMG gesture recognition models. Results showed that the overall recognition accuracy of ETDTBN were 86.95% and 84.15%, respectively. Both accuracies are optimal, proving the effectiveness of the model.



Key wordssurface electromyogram (sEMG)      gesture recognition      enhanced two-dimensional feature      two-branch network      self-adaptive feature fusion mechanism     
Received: 26 September 2023      Published: 23 October 2024
CLC:  TP 393  
Fund:  国家自然科学基金资助项目(51875524, 61873240);浙江大学CAD&CG国家重点实验室开放课题资助项目(A2210).
Cite this article:

Wanliang WANG,Jie PAN,Zheng WANG,Jiayu PAN. Recognition method of surface electromyographic signal based on two-branch network. Journal of ZheJiang University (Engineering Science), 2024, 58(11): 2208-2218.

URL:

https://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2024.11.002     OR     https://www.zjujournals.com/eng/Y2024/V58/I11/2208


基于双分支网络的表面肌电信号识别方法

针对目前表面肌电信号(sEMG)手势识别细节信息提取不充分,对相似手势区分困难的问题,提出基于加强二维化特征的双分支网络(ETDTBN)模型. 该模型通过加强二维化方法生成二维特征图,使用多层卷积神经网络(ML-CNN)提取sEMG的空间特征,利用双向门控循环单元(Bi-GRU)提取原始信号的时序特征. 考虑到不同的特征对网络的影响程度不同,引入自适应特征融合机制对不同分支进行融合,强化有用特征并弱化无用特征,提高表面肌电识别的准确率. 实验在电极偏移和不同受试者2种情况下对ETDTBN进行训练与测试,与主流的肌电手势识别模型进行对比. 可知,ETDTBN的总体识别准确率分别为86.95%和84.15%,准确率均为最优,证明了该模型的有效性.


关键词: 表面肌电信号(sEMG),  手势识别,  加强二维化特征,  双分支网络,  自适应特征融合机制 
Fig.1 Overall framework of ETDTBN
Fig.2 Detail of two-branch structure
Fig.3 Unfolded structure of Bi-GRU
Fig.4 Structure of self-adaptive feature fusion
Fig.5 Diagram of hand gesture movement
Fig.6 Window analysis method
Fig.7 Structure of ETDTBN network
网络层操作卷积核/步长输出/通道零补
Input—/—300/16
ML-CNNConv2d5*5/1*115*15/64
MaxPool2*2/2*28*8/64
Conv2d3*3/1*14*4/128
MaxPool2*2/2*24*4/128
FC—/—512/—
FC—/—128/—
Bi-GRUBi-GRU—/—256/16
Conv1d3/2128/32
Conv1d1/1128/32
Conv1d3/264/64
Conv1d1/164/64
FC—/—512/—
FC—/—128/—
ClassSAFF—/—128/—
FC—/—64/—
FC—/—5/—
Tab.1 Structural parameters of ETDTBN
方法Pc/%Po/%
HCHORFWEWF
KNN+FE[30]28.21±0.009.23±0.0094.90±0.00100±0.00100±0.0066.67±0.00
SVM+FE[31]42.64±0.0018.97±0.0087.82±0.00100±0.00100±0.0070.49±0.00
CNN[8]90.72±6.9713.42±7.8223.21±10.1596.79±2.5896.75±5.2964.18±2.73
CNN+FE29.89±4.2433.91±16.2695.01±3.6098.90±1.3191.58±10.6670.87±2.74
CNN+FE+ETD85.56±4.4440.33±13.5075.20±8.0598.85±1.1886.18±5.2478.24±2.26
RESNET+FE[32]31.09±3.9435.17±10.9690.78±4.8898.92±1.2992.22±3.2670.78±2.66
Bi-GRU[33]84.10±8.195.41±5.0972.67±10.26100±0.0099.34±1.0972.04±2.35
LSTM[34]73.64±11.844.33±1.9971.13±18.33100±0.0099.40±1.0270.88±3.55
TRANSFORMER[35]80.64±5.8420.15±3.5366.17±8.6298.55±1.3889.14±2.1966.14±3.25
LCNN[36]93.13±2.9812.51±3.5381.03±6.5498.26±0.5291.08±4.9076.38±0.94
TDACAPS[14]97.59±2.6274.87±15.7195.18±4.4298.56±1.8255.39±16.8784.77±0.82
ETDTBN99.80±0.4166.36±6.9069.85±7.44100±0.0099.85±0.3686.95±1.64
Tab.2 Recognition effect of each method under electrode displacement
Fig.8 Classification accuracy of different model in case of electrode displacement
Fig.9 Comparison of confusion matrix of different method under electrode displacement
方法Pc/%Po/%
HCHORFWEWF
KNN+FE[30]97.18±0.0072.99±0.0047.95±0.0093.50±0.0042.14±0.0070.75±0.00
SVM+FE[31]64.27±0.0086.24±0.0051.71±0.00100.00±0.0052.99±0.0071.04±0.00
CNN[8]87.35±3.4566.63±0.5858.44±2.0998.94±0.6540.85±1.0570.49±0.86
CNN+FE71.99±4.1690.51±1.8580.87±7.5999.82±0.4931.39±7.5175.06±0.18
CNN+FE+ETD82.63±2.3780.13±3.8882.22±6.9799.25±0.7833.68±8.5577.57±0.78
RESNET+FE[32]73.79±3.9685.22±2.7881.17±6.1999.22±0.6532.11±6.9574.96±0.26
Bi-GRU[33]82.06±6.7166.26±7.4237.35±3.8494.65±2.5263.98±5.0268.93±0.38
LSTM[34]78.79±6.8160.85±5.5640.32±3.9699.27±0.7254.03±6.7767.08±1.11
TRANSFORMER[35]83.09±2.8159.05±6.5633.22±3.8897.57±0.9255.13±6.4465.33±1.08
LCNN[36]95.95±2.1180.78±3.4662.25±5.3399.69±0.1546.95±3.1677.26±0.53
TDACAPS[14]98.25±3.8984.98±7.1282.48±5.9698.24±0.6244.75±5.5081.90±1.09
ETDTBN99.75±0.1575.51±1.8595.27±2.5499.93±0.0550.21±0.4584.15±0.41
Tab.3 Recognition accuracy of each method under different subject
Fig.10 Change of classification accuracy of different model in case of different subject
Fig.11 Comparison of confusion matrix of different method under different subject
方法Po/%
电极偏移情况下不同受试者情况下
ETDTBN +Sum84.28±1.5383.17±0.82
ETDTBN +Concat82.06±2.0781.21±0.97
ETDTBN+SAFF86.95±1.6484.15±0.41
Tab.4 Effect of fusion strategies on classification accuracy of sEMG signals
方法Np/106C/MBte/stp/str/ms
KNN+FE[30]0.78±0.0186.86±1.220.020±0.001
SVM+FE[31]0.48±0.0177.06±1.620.030±0.001
CNN[8]4.98162.7322.65±0.98148.61±3.380.078±0.003
CNN+FE0.76117.3014.13±0.46101.32±2.110.066±0.002
CNN+FE+ETD1.15184.4820.19±0.65153.51±3.650.086±0.002
RESNET+FE[32]0.55336.8821.96±0.52147.53±4.060.071±0.002
Bi-GRU[33]1.41118.1016.76±0.50160.49±2.980.078±0.002
LSTM[34]1.52146.3517.14±0.59168.25±3.160.082±0.002
TRANSFORMER[35]2.49335.6824.16±0.66187.23±4.560.079±0.002
LCNN[36]1.77533.5021.06±0.62180.85±4.290.082±0.003
TDACAPS[14]0.87741.38216.45±6.161978.12±14.181.047±0.030
ETDTBN3.73321.4117.85±0.48156.28±3.990.076±0.002
Tab.5 Computational resource analysis for all methods
方法Po/%
ChenNet[8]68.23±2.0771.74±3.6767.25±4.49
HuNet[10]81.18±5.6982.21±5.6969.52±3.94
WeiNet[37]82.06±3.4780.72±4.9753.27±5.77
ETDTBN82.59±4.4683.01±3.4277.16±3.98
Tab.6 Recognition effectiveness of each method on public dataset
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