A functional electrical stimulation system for human walking inspired by reflexive control principles

Abstract

This study presents an innovative multichannel functional electrical stimulation gait-assist system which employs a well-established purely reflexive control algorithm, previously tested in a series of bipedal walking robots. In these robots, ground contact information was used to activate motors in the legs, generating a gait cycle similar to that of humans. Rather than developing a sophisticated closed-loop functional electrical stimulation control strategy for stepping, we have instead utilised our simple reflexive model where muscle activation is induced through transfer functions which translate sensory signals, predominantly ground contact information, into motor actions. The functionality of the functional electrical stimulation system was tested by analysis of the gait function of seven healthy volunteers during functional electrical stimulation–assisted treadmill walking compared to unassisted walking. The results demonstrated that the system was successful in synchronising muscle activation throughout the gait cycle and was able to promote functional hip and ankle movements. Overall, the study demonstrates the potential of human-inspired robotic systems in the design of assistive devices for bipedal walking.

On prosthetic control: A regenerative agonist-antagonist myoneural interface

“…To close the loop, afferent feedback from the prosthesis into the peripheral nervous system is achieved through functional electrical stimulation (FES) of the antagonist mus cle (through implanted stimulation electrodes) to control the position or force applied on the mechanically linked agonist muscle (or vice versa). FES has been widely implemented in numerous therapeutic and prosthetic applications, including numerous U.S. Food and Drug Administration-approved devices for respiration, bladder control, ambulation, and restoring hand function (23)(24)(25)(26). A full review of the stimulation methodology, advantages, and limitations can be found in (23).…”

Advances in neuroprosthetic management of foot drop: a review

“…Results showed an increment in plantarflexion during pre-swing and dorsiflexion in swing. A decrease in knee extension during a stance and an increase in the knee flexion during a swing and extension during heel contact were also observed [36].…”

“…However, open-loop stimulation strategies are a simple approach that focuses on controlling the moment of stimulation. The systems that apply this type of strategies require continuous attention because they do not adapt the stimulation applied according to muscle response [36]. This has led to the development of closed-loop strategies that are more stable and robust and are able to control the position or force generated by modulating the different parameters that characterize the stimulation.…”

“…Moreover, results suggested that the combination of flexo-extensor muscle stimulation with 1 h of walking each day translates into better walking without FES-assistance in patients with a chronic hemiplegia [61]. Meng et al (2017) presented Runbot II and III, two versions of a transcutaneous FES system which use IMUs and FSRs placed under the heel and the first metatarsal for gait event detection. The stimulation was applied to the tibialis anterior, lateral gastrocnemius, biceps femoris, and rectus femoris.…”

Adaptive multichannel FES neuroprosthesis with learning control and automatic gait assessment

“…The fixed stimulation pattern was triggered with a foot switch and resampled to the current estimated step duration. Meng et al extended this approach to include four muscles, the quadriceps, hamstrings, tibialis anterior and gastrocnemius muscles [16]. In a previous study [17], the EMG muscle activity of ten healthy subjects during gait was recorded in relation to five gait events.…”