Angular momentum-based control of an underactuated orthotic system for crouch-to-stand motion

Laubscher, Curt A.; Farris, Ryan J.; Sawicki, Jerzy T.

doi:10.1007/s10514-020-09938-5

Cited by 3 publications

(3 citation statements)

References 20 publications

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“…Each actuator is driven by a 70 W brushless DC motor using a 3-stage toothed-belt transmission with a total speed-reduction ratio of 40.6:1. This provides a nominal output speed of 375 deg/s, stall torque of 35.7 Nm, and a continuous torque of 5.4 Nm [21,147]. Belts are employed in the transmission system to enable compliant behavior under load while also being lightweight and quiet.…”

Section: 1) Hk Exoskeleton By Laubscher Et Almentioning

confidence: 99%

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Wearable Lower-Limb Exoskeleton for Children With Cerebral Palsy: A Systematic Review of Mechanical Design, Actuation Type, Control Strategy, and Clinical Evaluation

Sarajchi¹,

Al-Hares

Sirlantzis

2021

IEEE Trans. Neural Syst. Rehabil. Eng.

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Children with a neurological disorder such as cerebral palsy (CP) severely suffer from a reduced quality of life because of decreasing independence and mobility. Although there is no cure yet, a lower-limb exoskeleton (LLE) has considerable potential to help these children experience better mobility during overground walking. The research in wearable exoskeletons for children with CP is still at an early stage. This paper shows that the number of published papers on LLEs assisting children with CP has significantly increased in recent years; however, no research has been carried out to review these studies systematically. To fill up this research gap, a systematic review from a technical and clinical perspective has been conducted, based on the PRISMA guidelines, under three extended topics associated with "lower limb", "exoskeleton", and "cerebral palsy" in the databases Scopus and Web of Science. After applying several exclusion criteria, seventeen articles focused on fifteen LLEs were included for careful consideration. These studies address some consistent positive evidence on the efficacy of LLEs in improving gait patterns in children with CP. Statistical findings show that knee exoskeletons, brushless DC motors, the hierarchy control architecture, and CP children with spastic diplegia are, respectively, the most common mechanical design, actuator type, control strategy, and clinical characteristics for these LLEs. Clinical studies suggest ankle-foot orthosis as the primary medical solution for most CP gait patterns; nevertheless, only one motorized ankle exoskeleton has been developed. This paper shows that more research and contribution are needed to deal with open challenges in these LLEs.

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Section: 1) Hk Exoskeleton By Laubscher Et Almentioning

confidence: 99%

“…Second, no clinical study has been conducted on the exoskeleton to assess the device's effectiveness directly, to the best of authors' knowledge. Third, since the simulation model may be inaccurate, it may not exactly show the mechanical device behavior [147].…”

Section: 1) Hk Exoskeleton By Laubscher Et Almentioning

confidence: 99%

Wearable Lower-Limb Exoskeleton for Children With Cerebral Palsy: A Systematic Review of Mechanical Design, Actuation Type, Control Strategy, and Clinical Evaluation

Sarajchi¹,

Al-Hares

Sirlantzis

2021

IEEE Trans. Neural Syst. Rehabil. Eng.

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“…Previously, our group developed an original actuator design which underwent benchtop evaluation [35,36]. The actuators have also been experimentally tested for crouch-to-stand motion [37], gait guidance [38], and assistive capabilities [39]. In these experiments, various issues were encountered, and hardware limitations were revealed.…”

Section: Introductionmentioning

confidence: 99%

Design and Evaluation of a Pediatric Lower-Limb Exoskeleton Joint Actuator

et al. 2020

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Lower-limb exoskeletons have undergone significant developments for aiding in the ambulation of adults with gait impairment. However, advancements in exoskeletons for the pediatric population have comparatively been lacking. This paper presents a newly developed joint actuator designed to drive the hip and knee joints of a pediatric lower-limb exoskeleton. The performance requirements associated with the actuators were determined based on a target audience of children ages 6–11 years old. The developed actuators incorporate a hybrid belt-chain transmission driven by a frameless brushless DC motor. One actuator underwent benchtop testing to evaluate its performance with respect to their torque production, bandwidth properties, backdrivability in terms of inertia and friction characteristics, speed capabilities, and operational noise levels. As a preliminary validation, a set of actuators were placed in a prototype orthosis to move a pediatric test dummy in gait tracking via state-feedback control. The results showed that the newly developed actuators meet the design specifications and are suitable for use in the pediatric exoskeleton being developed.

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An Anthropometrically Parameterized Assistive Lower Limb Exoskeleton

Laubscher

Farris

Bogert

et al. 2021

Journal of Biomechanical Engineering

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This paper presents a newly developed lower-limb exoskeleton tested for walking assistance. The novel exoskeleton design methodology uses additive manufacturing and a parametrized model based on user anthropometrics to give a person-specific custom fit. The process is applied to average children and a healthy adult, and a prototype device is fabricated for the adult to validate the feasibility of the approach. The developed prototype actuates the hip and knee joints without restricting hip abduction-adduction motion. To test usability of the device and evaluate walking assistance, user torque, mechanical energy generated, and muscle activation are analyzed in an assisted condition where the subject walks on a level treadmill with the exoskeleton powered. This is compared to an unassisted condition with the exoskeleton unpowered and a baseline condition with the subject not wearing the exoskeleton. Comparing assisted to baseline conditions, torque magnitudes increased at the hip and knee, mechanical energy generated increased at the hip but decreased at the knee, and muscle activations decreased in the Biceps Femoris and increased in the Vastus Lateralis. The presented preliminary results are inconclusive on whether the newly developed exoskeleton can assist in walking though show promise for basic usability of the device.

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Angular momentum-based control of an underactuated orthotic system for crouch-to-stand motion

Cited by 3 publications

References 20 publications

Wearable Lower-Limb Exoskeleton for Children With Cerebral Palsy: A Systematic Review of Mechanical Design, Actuation Type, Control Strategy, and Clinical Evaluation

Wearable Lower-Limb Exoskeleton for Children With Cerebral Palsy: A Systematic Review of Mechanical Design, Actuation Type, Control Strategy, and Clinical Evaluation

Design and Evaluation of a Pediatric Lower-Limb Exoskeleton Joint Actuator

An Anthropometrically Parameterized Assistive Lower Limb Exoskeleton

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