A Bi-Directional LSTM Network for Estimating Continuous Upper Limb Movement From Surface Electromyography

Chenfei Ma, Chuang Lin, Oluwarotimi Williams Samuel, Weiyu Guo, Hang Zhang, Steve Greenwald, Lisheng Xu, Guanglin Li

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

In human-machine interaction systems, continuous movement estimation methods occupy an important position because they are more natural and intuitive than pattern-recognition methods. Essentially, arm position is decided by the shoulder and elbow joint angles. However, the various deformations of muscles around the shoulder and elbow often lead to difficulties in sensor fixation, which results in a loss of synchronization between the surface electromyography (sEMG) signals and joint angles. In order to accurately estimate movement angles using sEMG in situations where the sEMG is not synchronized with joint angles, we utilized a bi-directional long short-term memory (Bi-LSTM) network rather than other deep learning methods to estimate non-dominant arm movements, based on the sEMG signal from the dominant arm. This estimation protocol was designed to avoid a multiplicity of sensors and to simulate more complicated loss of synchronization problems). The performance of the Bi-LSTM was compared with multilayer perceptrons (MLPs), convolutional neural networks (CNNs), and a long short-term memory network (LSTM). The Pearson correlation coefficient (cc) between the estimated and target joint angle sequences was calculated to evaluate the performance of each neural network. The Wilcoxon signed-rank results showed that the Bi-LSTM model significantly outperformed the MLP, CNN, and LSTM models (tested with completely untrained newly recorded free movements).
Original languageEnglish
Pages (from-to)7217-7224
Number of pages8
JournalIEEE Robotics and Automation Letters
Issue number4
Early online date14 Jul 2021
Publication statusPublished - 29 Jul 2021

Keywords / Materials (for Non-textual outputs)

  • Machine learning for robot control
  • continuous movement estimation,
  • surface electromyography
  • free movements test


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