Session: 15-01-01: ASME International Undergraduate Research and Design Exposition

Paper Number: 148641

148641 - User-Optimized Variable Joint Stiffness Design for Ankle Foot Motion Control in Orthoses and Exoskeletons 

Foot drop, also known as drop foot, is a condition when individuals are unable to lift the front part of the foot due to neurological or muscular weaknesses, which leads to the dragging of the foot and toe on the ground during walking. This gait abnormality significantly impairs mobility and often results in an increased risk of falls. This condition affects millions of people, severely limiting independence and reducing the quality of an individual's life. 

To address this problem, we developed a novel, biomimetic, and variable stiffness and compliant ankle joint that mimics the natural biomechanics of the human ankle to improve both the comfort and functionality of the orthosis. To address the need for a personalized fit and dynamic adaptability, we utilized advanced manufacturing techniques. The variable stiffness ankle joint is manufactured using a dual extruder 3D printer, employing both PLA and TPU filaments. This method allows for precise control over the material properties and structural integrity of the joint, facilitating the development of the ankle joint that can be finely adjusted to meet custom user joint stiffness.

The innovations include the design and development of various links that enable the analysis of stiffness properties through changes in design and material selection. This approach allows us to explore different configurations and their effects on the performance of the joint in real-world applications.

An automated measurement system was also designed to collect clinical data from human subjects. This system employs reaction torque sensors and a DC motor to measure the actual stiffness of the ankle joint. Additionally, the developed compliant variable ankle joints were characterized using an MTS machine and load sensors, providing comprehensive data on their behavior under various load conditions.

The optimization of the joint design was conducted using Ansys for structural analysis and MATLAB Simscape for motion analysis, focusing on the flexible link material properties. This enabled us to refine the joint for optimal performance and durability.

Finally, the developed compliant ankle joints were first tested on the automated measurement system and then with human subjects to assess their performance. This testing confirmed the effectiveness of the joint in improving mobility and safety for individuals suffering from foot drop.

Our research marks a significant advancement in orthotic technology, promising to enhance mobility and quality of life for those affected by foot drop. By integrating biomimetic design with an automated testing method, this work sets a new standard for personalized, effective orthotic solutions.

Presenting Author: Vanessa Young kennesaw state university

Presenting Author Biography: Vanessa Young is an undergraduate research assistant in the mechanical engineering department at Kennesaw State University.

Authors:

Vanessa Young kennesaw state university
Lucas Schwenck Kennesaw State University
Connor Talley Kennesaw State University
Gwenevere Wrye kennesaw state university
Coskun Tekes Kennesaw State University
Geza Kogler Kennesaw State University
Ayse Tekes Kennesaw State University