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摘要: 表面肌电信号随着时间的变化而改变,这将影响运动模式的分类精度.传统人体下肢假肢运动模式的识别算法不能保证在整个肌电控制时间内达到对运动模式的有效识别.为了解决这些问题,本文提取步态初期200ms的信号的特征值,将无监督和有监督的Kohonen神经网络算法应用到大腿截肢者残肢侧的步态识别中,并与传统BP神经网络进行了对比.结果表明,有监督的Kohonen神经网络算法将五种路况下步态的平均识别率提高到88.4%,优于无监督的Kohonen神经网络算法和BP神经网络.
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关键词:
- 表面肌电信号 /
- 智能假肢 /
- 特征提取 /
- 有监督Kohonen神经网络 /
- 步态识别
Abstract: Surface electromyography (sEMG) is changeable with time, which will affect the classification accuracy. The traditional recognition method cannot guarantee its effectiveness within whole control cycle for lower limb movement. This paper extracts the feature from initial 200ms EMG, applies Kohonen and supervised Kohonen neural networks, and compares the result with BP neural network. Experimental results show that supervised Kohonen neural network is superior to the other two algorithms. The average recognition rate can be increased to 88.4% for five kinds of terrains. -
表 1 大腿截肢者5种步态的功率谱比值
Table 1 Power spectrum ratio of five gaits
平地 上楼梯 下楼梯 上斜坡 下斜坡 股直肌 6.7530 5.2074 4.2859 3.7062 2.0640 股外侧肌 2.6390 3.0697 2.8058 3.5630 3.0875 股二头肌 1.5962 2.4860 3.5804 2.2074 3.6307 半腱肌 4.8403 5.2830 4.7083 5.0642 4.0974 阔筋膜张肌 2.3746 3.4390 5.0261 5.9803 6.7549 臀大肌 3.9827 3.7650 3.0548 3.2769 2.9067 表 2 大腿截肢者股外侧肌的4阶模型参数
Table 2 The 4th order model parameters of vastus
${\boldsymbol A\boldsymbol R}_1$ ${\boldsymbol A\boldsymbol R}_2$ ${\boldsymbol A\boldsymbol R}_3$ ${\boldsymbol {AR}}_4$ 平地 4.3927 4.2654 4.3761 4.1862 上楼梯 -2.9846 -2.7062 -2.6873 -2.8306 下楼梯 4.6834 4.7635 4.5980 2.2074 上斜坡 3.1370 3.2537 3.3207 3.1752 下斜坡 -0.8349 -0.7859 -0.8263 -0.7952 表 3 步态识别结果
Table 3 The results of gait recognition
平地 上楼梯 下楼梯 上斜坡 下斜坡 训练样本数 100 100 100 100 100 测试样本数 50 50 50 50 50 识别样本数 47 45 42 43 44 识别率 (%) 94 90 84 86 88 平均识别率 (%) 88.4 -
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