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Design and Control of a Single-Leg Exoskeleton with Gravity Compensation for Children with Unilateral Cerebral Palsy

Sarajchi, Mohammadhadi, Sirlantzis, Konstantinos (2023) Design and Control of a Single-Leg Exoskeleton with Gravity Compensation for Children with Unilateral Cerebral Palsy. Sensors, 23 (13). pp. 1-35. ISSN 1424-8220. (doi:10.3390/s23136103) (KAR id:101956)

Abstract

Children with cerebral palsy (CP) experience reduced quality of life due to limited mobility and independence. Recent studies have shown that lower-limb exoskeletons (LLEs) have significant potential to improve the walking ability of children with CP. However, the number of prototyped LLEs for children with CP is very limited, while no single-leg exoskeleton (SLE) has been developed specifically for children with CP. This study aims to fill this gap by designing the first size-adjustable SLE for children with CP aged 8 to 12, covering Gross Motor Function Classification System (GMFCS) levels I to IV. The exoskeleton incorporates three active joints at the hip, knee, and ankle, actuated by brushless DC motors and harmonic drive gears. Individuals with CP have higher metabolic consumption than their typically developed (TD) peers, with gravity being a significant contributing factor. To address this, the study designed a model-based gravity-compensator impedance controller for the SLE. A dynamic model of user and exoskeleton interaction based on the Euler–Lagrange formulation and following Denavit–Hartenberg rules was derived and validated in Simscape™ and Simulink® with remarkable precision. Additionally, a novel systematic simplification method was developed to facilitate dynamic modelling. The simulation results demonstrate that the controlled SLE can improve the walking functionality of children with CP, enabling them to follow predefined target trajectories with high accuracy.

Item Type: Article
DOI/Identification number: 10.3390/s23136103
Uncontrolled keywords: assistive robot; cerebral palsy; dynamic systems and control; gravity compensator; impedance control; kinematic analysis; lower-limb exoskeleton; unilateral exoskeleton; wearable robot
Subjects: T Technology > TJ Mechanical engineering and machinery > Control engineering
Divisions: Divisions > Division of Computing, Engineering and Mathematical Sciences > School of Engineering and Digital Arts
Depositing User: Mohammadhadi Sarajchi
Date Deposited: 05 Jul 2023 23:54 UTC
Last Modified: 05 Nov 2024 13:08 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/101956 (The current URI for this page, for reference purposes)

University of Kent Author Information

Sarajchi, Mohammadhadi.

Creator's ORCID: https://orcid.org/0000-0001-5185-6165
CReDIT Contributor Roles:

Sirlantzis, Konstantinos.

Creator's ORCID: https://orcid.org/0000-0002-0847-8880
CReDIT Contributor Roles:
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