In-Motion Manual Wheelchair Braking System

Overview

Currently, manual wheelchair users must have the strength and ability to control the speed and stop them with their own hands. There is a need for a lightweight, in-motion braking system that does not get in the user’s way when using their chair. The brakes need to be easy to reach when actively pushing the chair and leaning back. The challenge with this positioning on the wheel is it could mean the brake would end up being awkward and, in the way, when the user is moving their arms to push. Additionally, if the brake has a slip differential this could aid with safety concerns when operating the brake on a slope.

Objectives

Our teams’ objectives were to develop a safe and functional wheelchair braking system that will give users the ability to gradually slow down while also not impeding the wheelchair’s usability. This means that the wheelchair will remain foldable, and the wheels will also remain detachable, so we do not interfere with the day-to-day usability of their wheelchair.

Approach

To get started, our team needed to come up with a list of customer needs and requirements that our final design needed to be met. We then communicated with our sponsor along with other people who use wheelchairs commonly and asked them what their needs were before we told them ours. We did this so we could see if we were understanding the problem correctly, then we told them about our thoughts on the needs and they agreed on what they were looking for. An AHP was used to rank the importance of our needs, which helped us with our Pugh concept scoring which led us to our design, the disc brake. We then created a custom disc for the brake by using a file that we found online for the disc that is used for our calipers. To fit our design needs, we customized it to fit the three bolt holder by using SolidWorks. The SolidWorks model of the disc was created to test its durability before adding it to the wheelchair for testing. By doing this, we were accurately able to determine the dimensions needed for our disc. Our final prototype of the disc brake system was one that we have been pursuing and building off of since the beginning of the project. Throught the design process, our prototye has constantly changed but the overall system idea stayed the same. To test our design, we used a long slope with a constant decline ratio of 1:24 height and length. Measurements were taken for every detail and ten trial runs were performed for each variable to give us data that we could average. With the incline ratio of 1:24, the acceleration of the wheelchair reached almost 1.3 ft/s2 before coming unsafe. With our brake system the acceleration decreases to –0.175 ft/s2. Based on the ten trials on this incline, these calculations show that the wheelchair could come to a complete stop or move very slowly around 28 feet.

Outcomes

As a result of our project, we have made a design for Victorias Victory Foundation to help with their need to have users able to operate in motion wheelchair breaks. There is no current in-motion braking device on the market, so we did not save our sponsor money due to our prototype. This also means that there was no reduction in the manufacturing and production times because it is a one-of-a-kind device. With the addition of our new braking system, users can still remove the wheels in under 10 seconds, the same without a brake system, and put them back on in under 20 seconds. This is something that our group stressed throughout the project as it is important not to interfere with the current process these users take to take off and put on their wheels. All in all, this project resulted in a new and unique product to help wheelchair users live safer lives.