STEM 1, taught by Dr. Crowthers!
Course Description
STEM 1 mostly revolves around independent research projects and writing related to it. For our projects, we can choose our own topic based on anything we are interested. Dr. C. guides us throughout the whole process and helps us turn whatever idea we want to focus on into a feasible project.
Project Description
For individuals who use wheelchairs for mobility, navigating the world can be rather inconvenient, particularly when it comes to using staircases. The weight of wheelchairs equipped with the necessary features for stair climbing is typically around a couple of hundred pounds (Wine, n.d.). This, in addition to the incline of stairs and the wheels commonly utilized, results in most current wheelchairs not being able to climb stairs. Even the ones that can climb stairs do not do so in a way that allows the user to do so at the same speed and convenience as able-bodied individuals. By improving the speed and stability of stair-climbing wheelchairs, disabled individuals can travel through society similarly to able-bodied individuals, reducing the time spent doing simple tasks such as climbing stairs, allowing users to spend more time participating in activities of their choosing. An improved stair-climbing wheelchair would enable individuals who use wheelchairs for mobility to navigate society more easily, quickly, and efficiently.
Abstract
Currently, climbing stairs is virtually impossible for those confined to wheelchairs, which reduces the number of activities they can participate in, the quality of their participation, and increases the amount of time certain tasks take. These issues are caused by the weight of wheelchairs, the stair incline, speed, and wheels utilized, and they can be tackled by improving wheelchair speed capabilities, which requires the regulation of bodily stress in order to safely reach desired speeds without putting a significant amount of excess stress on the body pounds (Freedom Mobility). This project aimed to achieve this through the use of track wheels, which provide smooth movement, 48-voltage motors, which provide the necessary power and speed, and a self-balancing module, which is the main cause of reduced stress. The self-balancing module is successful due to the minimal angle changes and the reduced number of harsh movements. Through simulating a wheelchair with the previously stated implementations on a staircase, stress levels of the lumbar spine, femur, and hip bones were measured at different speeds, stair angles, and inclines, repeating each test for ascending and descending the staircase. This was done through Fusion software, and the resulting stress distributions were consistent across different speeds, inclines, angles, and directions, which leads to the conclusion that the implementations are successful at improving the speed and safety of stair-climbing wheelchairs.
Keywords: self-balancing, stress, wheelchairs, speed
Click here to view my research proposal!
Engineering Problem
The problem this project aims to fix is the inconvenience of stair climbing for individuals confined to wheelchairs. They often have to go out of their way to climb stairs, which limits the amount they can achieve.
Engineering Goal
The project goal is to simulate a stair-climbing wheelchair that climbs stairs quickly, efficiently, and safely, which includes minimizing the amount of stress placed on the body.
Background
Current wheelchairs can rarely climb stairs, and the ones that are capable do so slowly and inefficiently.
In addition, stress is often placed on the body when using a wheelchair on stairs due to the weight of wheelchairs, the wheels utilized, and the angles stairs cause the body to be placed at when in a wheelchair. Since there is stress present, it is unsafe to increase the speed.
Procedure
In order to increase the speed, 2 48-volt motors are used so the wheelchair has enough power to work inside, outside, and on staircases. To minimize stress, track wheels will be used in addition to a self-balancing module so the user always remains in an upright position and the wheelchair moves as smooth as possible. This design is simulated through Onshape, and stress distributions are measured in a climbing, descending, and neutral positions using Fusion.
Analysis
The stress graphs, while they do not show the desired results, they do show that stress is not necessarily increased due to the angle of the wheelchair. The back-tilted distributions have slightly higher stress distributions than the neutral distribution, but the forward-tilted distribution is significantly smaller than the other distributions. With more testing and tweaking, these results could be some of the first steps in proving the importance of a self-balancing module.
Conclusion
For the forward-tilted distribution, the self-balancing module was successful at not only keeping stress consistent with that of the neutral position, but even significantly decreasing it. The neutral position stress distribution has similar levels to the forward-tilted distribtuion, which shows that stress is kept relatively consistent throughout the entire body. Future steps involving minimizing stress to the same degree the backward-tilted model did.
References
All about 48V / Mild Hybrid technology | SEG Automotive. (n.d.). Www.seg-Automotive.com. https://www.seg-automotive.com/48v/mild-hybrid-technology/
Do All Electric Wheelchairs Have Lithium Batteries? (2024, May 10). MANLY - a Leader in the Battery Field. https://manlybattery.com/do-all-electric-wheelchairs-have-lithium-batteries/
Winter, B., Buholzer, P., and Gemperle, T. (n.d.) Mobility, freedom and independence with the stair climbing wheelchair BRO. Scewo. https://www.scewo.com/en/
Hu, G. (2023, December 14). Most Powerful Wheelchair Motor and Controller (Beginner’s Guide). Jiecang.com; 浙江捷昌线性驱动科技股份有限公司. https://www.jiecang.com/article/most-powerful-wheelchair-motor-and-controller-beginner-s-guide.html
JerryRigEverything. (2022). The Worlds Most Advanced Wheelchair! - (It Climbs Stairs!?!) [Video]. Youtube. https://www.youtube.com/watch?v=hxf-fIubkMs
Review, T. R. (2023, March 28). Opening the Skies to Passengers Who Use Wheelchairs | The Regulatory Review. Www.theregreview.org. https://www.theregreview.org/2023/03/28/welch-ross-opening-the-skies-to-passengers-who-use-wheelchairs/
Nevzorov. (2020). Stair Climbing All Terrain Wheelchair Caterwil GTS 4WD. Caterwil.com. https://caterwil.com/product/stair-climbing-all-terrain-wheelchair-caterwil-gts-4wd/
(2019). Tracks vs Wheels: Advantages and Disadvantages. LiteTrax. https://litetrax.com/wheels-vs-tracks-advantages-disadvantages/
Wine, B. (n.d.). How much does an Electric Wheelchair Weigh? Freedom Mobility https://www.freedomhme.com/blog/post/how-much-does-an-electric-wheelchair-weigh-
Wong, J. Y., and Huang, W. (2006). “Wheels vs. tracks” – A fundamental evaluation from the traction perspective. Journal of Terramechanics, 43(1), 27–42. https://doi.org/10.1016/j.jterra.2004.08.003
Welch-Ross and Menzies. (2023) Opening the Skies to Passengers Who Use Wheelchairs. The Regulatory Review. https://www.theregreview.org/2023/03/28/welch-ross-opening-the-skies-to-passengers-who-use-wheelchairs/
Zhu, Y., Li, H., Lyu, S., Shan, X., Jan, Y.-K., and Ma, F. (2023). Stair-climbing wheelchair proven to maintain user’s body stability based on AnyBody musculoskeletal model and finite element analysis. PLOS ONE, 18(1), e0279478. https://doi.org/10.1371/journal.pone.0279478
(2024, July 12). 48V Electric Motor. Valeo. https://www.valeo.com/en/catalogue/pts/48v-electric-motor/
(n.d.). 48 volt: what it is and why it’s an important innovation. Dalroad. https://www.dalroad.com/resources/48-volt-what-it-is-and-why-its-important/