An Event-Driven Closed-Loop System for Real-Time FES Control

Active functional rehabilitation procedures, exoskeleton application and prosthesis employment are essential tools for the society life reinstatement of subjects affected by neuromuscular disorders or victims of serious physical accident. In this paper we propose a closed-loop system for the control of the Functional Electrical Stimulation (FES) based on the Average Threshold Crossing (ATC) event-driven processing technique applied to the sEMG signal. It allows an energy saving, low complex, and real-time muscle activity monitoring suitable for bio-feedback lines applications. Two functional modalities are implemented: self-administered stimulation, in which a person is able to self-stimulate herself/himself, and two-subjects stimulation, that covers the standard rehabilitation flow in which both the therapist and the patient are involved. The system has been tested on 19 healthy subjects to evaluate its performance in term of reproducibility between the voluntary movement and the stimulated one, obtaining a median value of the correlation coefficient, used as similarity measurement, above 0.9 across a wide range of benchmark movements. The promising results confirm the feasibility of controlling myoelectric exoskeleton and prosthesis with the ATC processing approach.