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.
Highlights
Functional electrical stimulation (FES) has been widely used in rehabilitation strategies for neurologically impaired individuals.[1,2,3,4,5,6] The purpose of an FES intervention is to enable functional movement by replacing or assisting with a person’s voluntary muscle activation
An example of the stimulation sequences and real-time processed signals from the force sensitive resistors (FSRs) and motion sensor are provided in Figure 4, for one participant walking with stimulation at his or her self-comfortable speed
All participants achieved a gait pattern with FES similar to their voluntary treadmill gait, as shown in Figure 5, which indicates the FES does not have a negative effect on the gait pattern
Summary
Functional electrical stimulation (FES) has been widely used in rehabilitation strategies for neurologically impaired individuals.[1,2,3,4,5,6] The purpose of an FES intervention is to enable functional movement by replacing or assisting with a person’s voluntary muscle activation. Crucial to the functional effectiveness of an FES system for gait is the correct timing of the applied stimulation within the gait cycle.[8] The simplest method to control the timing of the stimulation is by manual button press or foot switch and is used in the majority of commercial products. In the 1960s, Liberson et al.[9] proposed the first portable device for correcting drop foot by stimulating the peroneal nerve in the swing phase, detected via a foot switch. The open-loop system applies surface stimulation to the quadriceps, gluteal muscles and common peroneal nerve and is controlled through a hand switch integrated into a walking frame. Open-loop control is a simple and reliable approach to controlling the stimulation, it requires the continuous attention of the operator, and any mistiming of stimulation can result in abnormal muscle synchronisation within gait cycle
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Schedule a callMore From: Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine
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