Compensating for fatigue-induced time-varying delayed muscle response in neuromuscular electrical stimulation control

Abstract

Neuromuscular electrical stimulation (NMES), often called functional electrical stimulation (FES), is a prescribed treatment for various neuromuscular disorders. When applied to articulate a person's limb, the respective skeletal muscle groups are known to rapidly fatigue compared to muscles activated by the nervous system. Recent results have shown that muscles have a delayed response to electrical stimulation, and more recent results indicate that this delayed response increases as the muscle fatigues. A NMES control method is developed in this chapter as a means to compensate for the varying input delay for the uncertain nonlinear dynamics for the lower limb. Experimental results are provided to demonstrate the performance of the developed controller.