Keywords

Variable Stiffness, Ankle foot orthosis, Variable stiffness mechanisms, VS-AFO, orthosis, orthotic

Subject Categories

Biomechanics and Biotransport | Biomedical Engineering and Bioengineering

Abstract

Conventional ankle–foot orthoses (AFOs) typically employ static stiffness profiles that do not replicate the dynamic quasi-stiffness of the human ankle during gait. Variable stiffness mechanisms (VSMs) offer a promising alternative solution for gait pathologies, such as foot drop and post-stroke hemiparesis; however, their implementation is limited by the lack of accurate mathematical models capable of predicting force and stiffness characteristics. The objective of this thesis is to develop and validate comprehensive mathematical models describing the kinematics and kinetics of a novel variable stiffness ankle–foot orthosis (VS-AFO). This study derives governing equations to characterize how mechanical adjustments influence the force transmission and effective stiffness of the VS-AFO. Specifically, investigates the effect of modifying the effective beam length through which forces are transferred from the foot plate to the shank. Euler–Bernoulli beam theory was employed to establish a predictive stiffness model for the device. The proposed model was validated experimentally using a custom-designed test bench, where theoretical stiffness predictions are compared with empirical measurements. This research provides a foundational framework for the development of a “smart” VS-AFO which allows for patient specific tuning and real-time stiffness modulation, with the potential to improve mobility outcomes for individuals with lower-limb impairments.

Completion Date

2026

Semester

Summer

Committee Chair

Choi, Hwan

Degree

Master of Science (M.S.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Format

PDF

Document Type

Thesis

Language

English

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