A Multifaceted Hybrid ES-Robotic Device for Gait Training in Individuals with Neurological Disorders

Abstract The integration of robotics and Electrical Stimulation (ES) in neurorehabilitation combines the precise execution of complex tasks enabled by robotics with motor learning, muscle conditioning, and cardiovascular fitness induced by ES. We propose a hybrid lower-limb exoskeleton for gait training to maximize these benefits. Two neuromuscular electrical stimulators and a 4-degrees-of-freedom motorized exoskeleton were combined with different modalities: ES-motor cooperative integration for the swinging knee, synchronized but independently operating ES and motors for the hip both in swing and in stance phases, and for the knee during stance, and ES-only for the non-actuated ankle. Two conditions - exoskeleton only and hybrid - were compared on twelve non-disabled subjects and eleven participants with neurological disorders. Electrical stimulation reduced the output motor torque at the knee by approximately 50%, while maintaining comparable movement performance (tracking errors <8° in both conditions and groups). Overall, the hybrid system was perceived as more usable by participants with neurological disorders compared to the exoskeleton alone, with an improvement of around 16%. These results are promising for developing lighter exoskeletons with potentially enhanced therapeutic benefits for motor learning.