Recalibration of myoelectric control with active learning

Katarzyna Szymaniak, Agamemnon Krasoulis, Kianoush Nazarpour

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Introduction: Improving the robustness of myoelectric control to work over many months without the need for recalibration could reduce prosthesis abandonment. Current approaches rely on post-hoc error detection to verify the certainty of a decoder's prediction using predefined threshold value. Since the decoder is fixed, the performance decline over time is inevitable. Other approaches such as supervised recalibration and unsupervised self-recalibration entail limitations in scaling up and computational resources. The objective of this paper is to study active learning as a scalable, human-in-the-loop framework, to improve the robustness of myoelectric control.

Method: Active learning and linear discriminate analysis methods were used to create an iterative learning process, to modify decision boundaries based on changes in the data. We simulated a real-time scenario. We exploited least confidence, smallest margin and entropy reduction sampling strategies in single and batch-mode sample selection. Optimal batch-mode sampling was considered using ranked batch-mode active learning.

Results: With only 3.2 min of data carefully selected by the active learner, the decoder outperforms random sampling by 4–5 and ~2% for able-bodied and people with limb difference, respectively. We observed active learning strategies to systematically and significantly enhance the decoders adaptation while optimizing the amount of training data on a class-specific basis. Smallest margin and least confidence uncertainty were shown to be the most supreme.

Discussion: We introduce for the first time active learning framework for long term adaptation in myoelectric control. This study simulates closed-loop environment in an offline manner and proposes a pipeline for future real-time deployment.
Original languageEnglish
Pages (from-to)1-11
Number of pages11
JournalFrontiers in Neurorobotics
Volume16
DOIs
Publication statusPublished - 15 Dec 2022

Keywords / Materials (for Non-textual outputs)

  • myoelectric control
  • active learning
  • machine learning
  • prosthetics
  • adaptation

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