Preliminary Evaluation of a Powered Lower Limb Orthosis to Aid Walking in Paraplegic Individuals

Abstract

This paper describes a powered lower-limb orthosis that is intended to provide gait assistance to spinal cord injured (SCI) individuals by providing assistive torques at both hip and knee joints. The orthosis has a mass of 12 kg and is capable of providing maximum joint torques of 40 Nm with hip and knee joint ranges of motion from 105° flexion to 30° extension and 105° flexion to 10° hyperextension, respectively. A custom distributed embedded system controls the orthosis with power being provided by a lithium polymer battery which provides power for one hour of continuous walking. In order to demonstrate the ability of the orthosis to assist walking, the orthosis was experimentally implemented on a paraplegic subject with a T10 complete injury. Data collected during walking indicates a high degree of step-to-step repeatability of hip and knee trajectories (as enforced by the orthosis) and an average walking speed of 0.8 km/hr. The electrical power required at each hip and knee joint during gait was approximately 25 and 27 W, respectively, contributing to the 117 W overall electrical power required by the device during walking. A video of walking corresponding to the aforementioned data is included in the supplemental material.

Design and control of a powered knee orthosis for gait assistance

“…5 shows the overall structure of fuzzy logic inference. The input force value of each FSR goes through fuzzification with membership function (1) and (2). The fuzzy logic inference rules are set according to Table II, with "L" stands for Large and "S" stands for Small.…”

“…Several powered lower limb orthoses have been developed, such as the Hybrid Assistive Limb by Sankai [1], Vanderbilt Exoskeleton by Goldfarb [2], ReWalk by Goffer [3], and eLeg by Ekso Bionics [4], to provide assistive functions at the wearer's lower limb joints in the sagittal plane. These devices were mainly designed for paraplegic gait assistance.…”

Design and Motion Control of a Lower Limb Robotic Exoskeleton

“…The user also has a remote control placed in his/her arm for Design, Control and Applications of Mechatronic Systems in Engineeringselecting different tasks, such as sit-to-stand or climbing stairs. The Vanderbilt exoskeleton [18,19] is developed to provide gait assistance to patients with spinal cord injuries. The device weights about 12 kg.…”

The influence of orthosis options on walking parameters in spinal cord-injured patients: a literature review

“…Farris et al 47 Single case study One complete SCI patient with injury in T10 2 PGO using power applied to the hip and knee joints. Walking speed was shown to be 0.20 m per second when walking with powered lower limb orthosis.…”

“…Nine studies analyzed gait parameters in SCI patients as powered orthoses and exoskeleton. [41][42][43][44][45][46][47][48][49] These studies had a low level of evidence according to the PEDro score (2/10). Powered lower limb orthoses such as the HAL-5 Type-C (hybrid assistive limb), which has five electric motors 45,50 the ReWalk powered orthosis (Argo Medical Technologies), 42,43 the wearable power assist locomotor (WPAL) 41 and the e LEGS powered orthosis (Berkeley Bionics) are all examples of commercially developed powered orthoses designed for walking by individuals with paraplegia.…”