Analysis of muscle activation patterns during walking in patients with foot drop: insights for the design of an advanced FES controller

This study focuses on the analysis of human walking after stroke for the design of a Functional Electrical Stimulation (FES) strategy for foot drop correction. Our approach is based on the analysis of muscle activation patterns from electromyography and ankle joint kinematic data. The objective of this work was to study the activation of the muscles of the lower leg during walking in three different walking speeds in patients affected by stroke with a foot drop syndrome. The purpose was to find any differences in muscle activation duration and intensity that should be taken into account in the definition of the muscle stimulation patterns of an FES foot drop controller. The results showed that plantar flexor muscles should also be included in our FES controller, especially at the end of the stance phase. The results confirmed a clear relation between walking speed and muscle activation. A novel concept design of an FES foot drop controller is proposed, with inputs as the walking speed of the subject and instantaneous gait phase extracted from inertial measurement units.