Assisting Stroke Gait with Cable Driven Lower Limb Rehabilitation Exoskeleton (C-LREX): Simulation Study

Abstract

Cable driven exoskeletons have demonstrated promising results in the rehabilitation of stroke survivors. Usually, the performance of an exoskeleton is tested via multiple experimental trials to allow iterative adjustment and optimization, which can be costly and time-consuming. Preliminary numerical model studies which quantify the effects of various design parameters on the exoskeleton's behavior and compare the responses of the impaired limb with and without the exoskeleton are valuable as they provide time and cost-effective means to fine-tune key design parameters while minimizing unnecessary testing. This study employed a generalized framework of cable driven exoskeleton analysis to investigate the ability of a cable driven lower limb rehabilitation exoskeleton (C-LREX) to correct stroke impaired gait and track reference healthy trajectories. Five different impaired gait patterns were studied. The simulation results demonstrated that the C-LREX model was able to assist the impaired limb to track the reference trajectory successfully in all impaired gait patterns except in the case of high deviation in the range of motion, which required a cable tension that exceed the allowable limit implemented in the model. This study confirmed that our developed simulation framework was able to test the C-LREX model ability to assist various impaired lower limb patterns in the sagittal plane during gait and determine the cable tension requirements. Future work includes expanding the framework to incorporate the frontal plane motion toward testing the performance of C-LREX in assisting three-dimensional impaired motion.

Keywords: Cable-driven exoskeleton, Lower-limb rehabilitation, Stroke gait impairment, Gait assistance, Numerical simulation