OPTIMAL SIZE OF CONSTRAINTS BETWEEN INNER TUBE SECTIONS

What is 2.671?

2.671 Measurement and Instrumentation is a class required for all Mechanical Engineering Undergraduates at MIT. It teaches how to design and conduct experiments, analyze results with an emphasis on uncertainty analysis, and effectively communicate and present these ideas. Along with weekly labs that teach the objective listed above, each student conducts their own experiment through the semester, called the Go Forth and Measure Project. I decided to perform an experiment that would help with the design of my low-cost wheelchair seat cushion, ultimately attempting to determine the optimal size of constraints between each air pocket in the inner tubes.

Abstract

A wheelchair seat cushion is being developed for use in developing countries to replicate the ROHO air cushion by constraining air flow between bike inner tube sections using zip ties. The circumference of zip tie constraints between inner tube sections was varied from 31 to 40 millimeters. For both the ROHO and inner tubes, video analysis was used to determine the change in three air cell sizes over time when one cell was subjected to a force. While the relative change in air cell size decreased with distance from applied force for both cushions, the time to reach the maximum area did not vary with distance for the inner tubes. An optimal circumference for zip tie constraints could not be determined from this experimental procedure.

My Contribution

The Go Forth and Measure Project is a completely self-led project, which means I designed and conducted the experiment myself. I performed video analysis through MATLAB and analyzed the data to observe the behavior of the ROHO cushion and my inner tube cushion. I gave a conference-style presentation, presented a poster, and wrote a full scientific paper for the project.