Abstract
This paper presents a simulation of bipedal locomotion to generate stimulation pulses for activating muscles for paraplegic walking with wheel walker using functional electrical stimulation (FES) with spring brake orthosis (SBO). A new methodology for paraplegic gait, based on exploiting natural dynamics of human gait, is introduced. The work is a first effort towards restoring natural like swing phase in paraplegic gait through a new hybrid orthosis, referred to as spring brake orthosis (SBO). This mechanism simplifies the control task and results in smooth motion and more-natural like trajectory produced by the flexion reflex for gait in spinal cord injured subjects. SBO can eliminate reliance on the withdrawal reflex and foot-ground clearance without extra upper body effort. The stored energy in the spring of SBO is used to replace stimulation pulses in knee flexion and reduce total required torque for the paraplegic walking with wheel walker. The study is carried out with a model of humanoid with wheel walker using the Visual Nastran (Vn4D) dynamic simulation software. Stimulated muscle model of quadriceps is developed for knee extension. Fuzzy logic control (FLC) is developed in Matlab/Simulink to regulate the muscle stimulation pulse-width required to drive FES-assisted walking gait and the computed motion is visualised in graphic animation from Vn4D. The simulation results show that SBO can be successfully used with FES for paraplegic walking with wheel walker with all the advantages discussed over the current hybrid orthoses available.
Highlights
Paraplegia is impairment in motor and/or sensory function of the lower extremities
Simulations were carried out using Matlab/Simulink with incorporation of humanoid with wheel walker model in Vn4D to illustrate the effectiveness of spring brake orthosis (SBO) in functional electrical stimulation (FES)-assisted walking with wheel walker
The reference trajectory is obtained from Winter [36] referring to the normal human gait based on anthropometric data of one paraplegic subject used in this paper
Summary
Paraplegia is impairment in motor and/or sensory function of the lower extremities. It is usually the result of spinal cord injury (SCI) which affects the neural elements of the spinal canal. A hybrid FES gait system concept called Spring-Brake-Orthosis (SBO) which combines mechanical braces (with coordinated joint locking mechanism) with an energy storage element mounted on it and FES to generate the swing phase of paraplegic gait is presented [8]. The new concept in hybrid orthotics provides solutions to the problems that affect current hybrid orthosis, including knee and hip flexion without relying on the withdrawal reflex or a powered actuator and foot-ground clearance without extra upper body effort. The use of SBO to overcome the problem associated with withdrawal reflex is presented by using spring for knee flexion to achieve minimum stimulation pulses for knee extension
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