Multifunction Toilet Wheelchair
The problem
Currently, in order to user the restroom, wheelchair users must leave their seats in order to use the toilet. This requires either using transfer techniques (shown on left), which comes with risk of injury, or a helper, which reduces personal freedom
Research
The two main health risks to consider in this design are pressure sores and hemorrhoids. The Reswick-Rogers pressure-time curve gives a model which works well except in short (2) and long (1) time frames. The second study evaluated the sitting habits of wheelchair users, and found most commonly there is a 2 hour period without weight shifts. This means we have an allowable pressure of 150 mmHg for 2 hours without weight shifting
Testing
In order to compare the support of the designed prototypes, a force sensing mat was used to create pressure maps for each design. I created a testing process, which compared support of 7 different seat designs. ANOVA and statistical analysis was used to arrive at a final design
Prototyping
For the selected design to work, I made a prototype using 3D printing, power tools, and sewing out of wood, nylon fabric, PVC, and PLA. The fastening system (on left) was designed in Solidworks and prototyped in real life, then it's functionality was tested using static loading FEA.
FEA
Applied torque was determined using hand calculations, and the assembly was mated to replicate the real life fastening system. Most of the stress was focused on the lower attachment, which was iterated upon until a design was created which could handle the applied stress
Conclusion and future work
I was able to create a prototype which was below our target pressure, and improved support compared to the past solution by 36%. The fastening system prototype was proven to be viable using FEA and in person prototype tests. A machined prototype would decrease mechanical interferences present in the initial prototype. This solution was also found to be the easiest to use, and most sanitary option out of the 7 designs. I am currently working on a paper to detail my findings.