Myoelectric Control for Upper-Limb Exoskeletons: A Decoder-Shaper-Controller Framework, Design Guidelines, and Future Directions

This review introduces a functional decoder-shaper-controller framework for continuous myoelectric control of upper-limb exoskeletons. The framework decomposes the system into intention estimation (decoder), assistance policy mapping (shaper), and actuator realization (controller). It critically examines representative approaches, highlights that shaper design lacks established methodologies, and identifies key open issues including inconsistent reporting of assistance levels and insufficient validation across degrees of freedom, users, and tasks. The paper provides design guidelines for systematic module-wise tuning and outlines future research priorities to bridge the gap between accurate intention decoding and safe, effective, generalizable assistance under real-world conditions.