Asymptotic optimal control of neuromuscular electrical stimulation

Muscle fatigue during electrical stimulation onsets early and is comparatively more substantial than during volitional contractions, hindering successful application of functional and therapeutic neuromuscular electrical stimulation (NMES). One of the avoidable causes of muscle fatigue can be attributed to the overstimulation during NMES. In this paper, a NMES controller is developed to minimize a quadratic cost functional to balance asymptotic trajectory tracking performance and control effort, potentially reducing overstimulation of the muscle. A Lyapunov-based analysis is used to prove the asymptotic convergence of closed-loop tracking error and asymptotic minimization of the given cost functional.