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Linkage-based Orthoses Designed for Individualized Motion Requirements


This dissertation presents and demonstrates a new design procedure for customized wearable devices that provide joint guidance, support, and increased mobility for individuals with hand or lower-leg impairments. This new procedure uses motion capture data to guide kinematic synthesis of closed-loop linkages that match the specific movement of an individual and is demonstrated in the design and evaluation of a mechanical thumb, a hands-free crutch and a knee-ankle-foot orthosis.

The mechanical thumb was designed using motion capture data of a thumb curling task. A geometric model of the resulting four-bar linkage moved smoothly between the task positions and matched the desired thumb tip physiological movement. Then, a hands-free crutch was designed with a four-bar linkage synthesized to match motion capture data defining the movement of an individual's knee joint during walking. Tests of a prototype demonstrated reduced hip-hiking and increased stride length compared to a fixed-knee hands-free crutch.

A six-bar knee-ankle-foot orthosis was designed to match both the angular movements at the knee and ankle joints and the metatarsal trajectory obtained from motion capture data of a natural walking gait in the sagittal plane. Tests of a prototype showed normal knee

function and stride lengths during walking. Optimization was combined with the kinematic synthesis procedure to match the metatarsal trajectory.

The result is a new design procedure to obtain simple and robust wearable devices for application as hand, knee, and knee-ankle-foot orthoses that match natural human movement kinematics.

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