Dimensionality Reduction for Classification of Object Weight from Electromyography

Authors

Elnaz Lashgari, Chapman UniversityFollow
Uri Maoz, Chapman UniversityFollow

Document Type

Article

Publication Date

8-16-2021

Abstract

Electromyography (EMG) is a simple, non-invasive, and cost-effective technology for measuring muscle activity. However, multi-muscle EMG is also a noisy, complex, and high-dimensional signal. It has nevertheless been widely used in a host of human-machine-interface applications (electrical wheelchairs, virtual computer mice, prosthesis, robotic fingers, etc.) and, in particular, to measure the reach-and-grasp motions of the human hand. Here, we developed an automated pipeline to predict object weight in a reach-grasp-lift task from an open dataset, relying only on EMG data. In doing so, we shifted the focus from manual feature-engineering to automated feature-extraction by using pre-processed EMG signals and thus letting the algorithms select the features. We further compared intrinsic EMG features, derived from several dimensionality-reduction methods, and then ran several classification algorithms on these low-dimensional representations. We found that the Laplacian Eigenmap algorithm generally outperformed other dimensionality-reduction methods. What is more, optimal classification accuracy was achieved using a combination of Laplacian Eigenmaps (simple-minded) and k-Nearest Neighbors (88% F1 score for 3-way classification). Our results, using EMG alone, are comparable to other researchers’, who used EMG and EEG together, in the literature. A running-window analysis further suggests that our method captures information in the EMG signal quickly and remains stable throughout the time that subjects grasp and move the object.

Comments

This article was originally published in PLoS ONE, volume 16, issue 8, in 2021. https://doi.org/10.1371/journal.pone.0255926

Recommended Citation

Lashgari E, Maoz U (2021) Dimensionality reduction for classification of object weight from electromyography. PLoS ONE 16(8): e0255926. https://doi.org/10.1371/journal.pone.0255926

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Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 License.