The problem: creating a wheelchair that can be adapted for its use in the beach
Thin was the final degree project of my Product Design Engineering degree. Marta de Bergua and me worked on a new concept of wheelchair for daily use that could be adapted to its use in the beach to let the users move on the sand and have a bath in the sea.
This project was the result of 12 weeks of collaboration with the Red Cross and the Municipal Institute for People with Disabilities of Barcelona.
Research and tests
During a couple of days we were testing the existing wheelchair that the Red Cross has in some the beaches of Barcelona. The main problems we found were:
- Getting into the water and leaving it.
- Traction problems.
- Corrosion.
- No possibility to access the beach with your own wheelchair.
- No daily wheelchairs that can be adapted for its use in the beach.
Common operations
Here you can see some of the videos we took when we were trying the wheelchairs. The wheels were obviously too small and it was difficult to move on the sand. In addition, getting out of the water was dangerous in case a wave hits you from the back.
Our goals
The primary goal was to design one of the lightest wheelchairs using carbon fiber and demonstrate its reliability according that carbon fiber is one of the best materials to resist corrosion in saline waters. To reach this we worked on a concept where the seat acts as the main frame: the chassis.
This main part is made of carbon fiber. In addition to this, a polyurethane foam part under the main seat surface is covered with carbon fiber creating a tubular structure that makes it really strong and lightweight.
The final wheelchair
This was the final design we made for the wheelchair. The frame was designed in carbon fiber and titanium to avoid corrosion and the final weight including wheels was 5,85 kgrs.
Adapting the wheelchair for its use in the beach
After the first stages of the project, we concluded that the best way to adapt the wheelchair for its use in the beach would be using huge wheels. We thought that a big wheel to put the wheelchair inside would give us a considerable surface in contact with the sand and would avoid getting stuck in the sand when going into the water or leaving it.
It was a crazy idea, but after all the calculations, the conclusions were:
- It would be disassembled and stored separately.
- It would displace the amount of water necessary to make it float: no need of additional pontoons.
- Tractioning the wheelchair would transmit the movement to the wheel or it would be easy to be pushed by somebody in case you need it. The calculations were done expecting the worst conditions and it had traction even in 8-10 degrees of inclination.
It was decided to continue on this but for making it possible and balance the weights, we had to remove the front weels because they were critical for the corrosion and a support was added in the back of the wheelchair to have the correct balance of weights.
Conclusions and engineering viability
We had several discussions with the Red Cross during the whole process and they thought that it would be an interesting solution for them. Actually they can store the elements necessary for its use in the beach and the wheeclhair designed for the daily use would fit with their needs without restricting its functionalities.
We also had to work on the technical drawings and calculations for the final deliverable. The floating line of the wheelchair was calculated below the neck of the user. Here you have some images of some of the calculations of reactions and the finite elements analysis.
The grade of this project was 10/10 and, as you can imagine, we were really happy after all the hours we spent on it!
Marta de Bergua and Jordi Parra / September 2005