title: Evoked electromyography-based closed-loop torque control in functional electrical stimulation.
abstract: This paper proposed a closed-loop torque control strategy of functional electrical stimulation (FES) with the aim of obtaining an accurate, safe, and robust FES system. Generally, FES control systems are faced with the challenge of how to deal with time-variant muscle dynamics due to physiological and biochemical factors (such as fatigue). The degraded muscle force needs to be compensated in order to ensure the accuracy of the motion restored by FES. Another challenge concerns the fact that implantable sensors are unavailable to feedback torque information for FES in humans. As FES-evoked electromyography (EMG) represents the activity of stimulated muscles, and also enables joint torque prediction as presented in our previous studies, here we propose an EMG-feedback predictive controller of FES to control joint torque adaptively. EMG feedback contributes to taking the activated muscle state in the FES torque control system into account. The nature of the predictive controller facilitates prediction of the muscle mechanical response and the system can therefore control joint torque from EMG feedback and also respond to time-variant muscle state changes. The control performance, fatigue compensation and aggressive control suppression capabilities of the proposed controller were evaluated and discussed through experimental and simulation studies.
authors.affiliation: DEMAR Project, INRIA Sophia-Antipolis and LIRMM, CNRS University of Montpellier, Montpellier 34095, France. qin.zhang@hust.edu.cn
authors.forename: Qin
authors.initials: Q
authors.lastname: Zhang
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Hayashibe
authors.forename: Christine
authors.initials: C
authors.lastname: Azevedo-Coste
mesh_terms: D000465:Algorithms; D001676:Biofeedback, Psychology / Q000379:methods* / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods*; D004599:Electric Stimulation Therapy / Q000379:methods; D004576:Electromyography / Q000379:methods*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000294:innervation / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019415:Torque