Passive Pressure Modulation Mechanism for Improved Locomotion
Streng, Conor; Vander Tuin, Aidan; Ro, Jin-Sae; Brossart, Caroline; Kaufman, Benjamin
2021-04
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Abstract
Our team was tasked with designing and fabricating a passive mechanism to assist with walking. Our sponsor, Steve Schrader, suffers from pes cavus, and experiences severe pain when walking. His current solution, the Disco Shoe, adds too much height and constrains blood flow in his foot, adding to his pain. The mechanism must reduce pressure in his metatarsal region and not impede his motion/allow for normative gait. It also must be affordable, durable, easy to clean, and be 3D printable. These requirements came from the sponsor and our own research into gait and similar products. To accomplish the requirements and their associated specifications, our team, with advice from Mr. Schrader came up with the Springblade design. This design aimed to absorb energy during heel strike and release it later to assist with push off, reducing pressure on the metatarsal region. The blades of the design also collapsed into a curved shape, mimicking rocker sole footwear, which is shown to reduce pressure on the foot. This design was analyzed using FEA (Hypermesh-Optistruct), in order to determine stress distributions and deformation. This allowed us to make predictions and some design changes prior to fabricating a physical prototype. We also performed multiple kinematic analyses of regular shoes vs. the Disco Shoe, the sponsor’s current solution. Using this analysis, we were able to create a standard for normative gait that the Springblade could be compared to. Following these analyses, the Springblade prototype was made using rubber. It was then tested in the Neurobionics lab alongside regular shoes and the Disco Shoe for comparison. After analyzing the data, we found that there was a slight reduction in the push off ground reaction force. Our analysis also showed a return to normative gait relative to the regular shoes. However, the overall length of the Springblade prototype made it difficult to push off, so that could have contributed to the data we obtained. The rubber was less stiff than the material we modeled with, so the blades collapsed more than anticipated, leading to less assistance during push off. After testing, several design changes were made, including reducing the length and number of blades. Blades were also thickened to increase stiffness. The sponsor’s orthotic was also integrated into the design. Moving forward, we recommend more iteration and prototyping. This will allow for more testing on the part of the sponsor, and he can continue to iterate on the design. Investigation into other methods of manufacturing will be beneficial since 3D printing will soon become expensive if used for every iteration. Testing with force or pressure plates might also improve feedback and design refinement.Deep Blue DOI
Subjects
ME450
Description
ME450 Capstone Design and Manufacturing Experience: Winter 2021
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Project
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