Technical developments of functional electrical stimulation to correct drop foot: Sensing, actuation and control strategies

Abstract

This work presents a review on the technological advancements over the last decades of functional electrical stimulation based neuroprostheses to correct drop foot. Functional electrical stimulation is a technique that has been put into practice for several years now, and has been shown to functionally restore and rehabilitate individuals with movement disorders, such as stroke, multiple sclerosis and traumatic brain injury, among others. The purpose of this technical review is to bring together information from a variety of sources and shed light on the field's most important challenges, to help in identifying new research directions. The review covers the main causes of drop foot and its associated gait implications, along with several functional electrical stimulation-based neuroprostheses used to correct it, developed within academia and currently available in the market. These systems are thoroughly analyzed and discussed with particular emphasis on actuation, sensing and control of open- and closed-loop architectures. In the last part of this work, recommendations on future research directions are suggested.

Changes in center of pressure displacement with the use of a foot drop stimulator in individuals with stroke

“…The WalkAide® is a battery operated, single-channel, asymmetrical biphasic stimulator with programmable pulse width and frequency that is utilized during walking as a functional electrical stimulation (FES) orthotic device (Melo et al, 2015). This small device (87.9 g, 8.2 cm(H) × 6.1 cm(W) × 2.1 cm(T)) attaches to a molded cuff located just below the knee (Fig.…”

Intensity- and Duration-Adaptive Functional Electrical Stimulation Using Fuzzy Logic Control and a Linear Model for Dropfoot Correction

“…Closed-loop control was an effective way to adjust the stimulation parameters automatically, and several control techniques have been proposed (17, 18). Negård et al applied a PI controller to regulate the stimulation intensity and obtain the optimal ankle dorsiflexion angle during the swing phase (19).…”

FES-Drop-Foot Correction: From Pre-programmed Patterns to Online Modulation

“…Events are the localized on a reference representative pattern and associated to stimulation triggering. Some closed-loop control approaches have been considered [2] but real-time control of stimulation parameters is still not available in existing devices. The modulation of FES intensity to provide a more optimized delivery of stimulation and also to regulate dorsiflexion in the presence of disturbances, such as fatigue, may increase the number of potential users of the technology [3].…”