Modified Wheelchair
with height adjusting mechanism
with height adjusting mechanism
As per WHO, around 11% of the world's population have motor disabilities and most of them depend on a wheelchair for mobility. Transferring wheelchair-bound people into cars is a problem that is faced globally and the accessories available to assist in the process are very expensive. So, we came up with a cost-effective solution - a height-adjustable wheelchair with a scissor link mechanism that uses a mechanical actuator.
Final Fabricated Wheelchair
I noticed this issue in my school days where the school superintendent who was wheelchair-bound had to struggle a lot to get into his car. So I knew that this was a problem faced by people. But to understand the criticality and convince my teammates and mentor, I went ahead and performed some foundational research by going through several articles, quora posts, and blogs.
Some of my findings
I came to understand that this was a widespread issue. Getting patients out of wheelchairs to cars is a big hassle and the wheelchairs which have such mechanisms were insanely expensive. There are dedicated training sessions for caregivers to transfer patients from wheelchairs to chairs.
In addition, I went ahead and interviewed 4 patients and a caretaker who were wheelchair bound with varying severities to understand their pain points better.
1) How do you get into cars and other vehicles?
2) What difficulties do you face?
3) What type of wheelchair do you have?
1) Users find it extremely difficult to get into a car even with a caretaker.
2) The handle of the wheelchair blocks them and makes the process difficult.
3) As the existing wheelchairs with height adjusting mechanisms are very expensive, they resort to normal wheelchairs and managing with them. Some look for buying pre-used wheelchairs as well.
Now that we figured out the problem, we went ahead and researched existing wheelchairs with a similar mechanism. After research, we found that none of the existing models were made using mechanical actuators. Though operating this would be difficult as it requires a lot of physical effort (as compared to pneumatic and hydraulic actuators), this was much more cost-effective and fit right with our motivations.
Some research papers we referred >The folding frame and the rigid frame wheelchairs are the widely used types of wheelchairs for the transportation of patients or those with walking disability. The rigid type wheelchair is chosen as it is easy, cost efficient and provides support for attaching the scissor mechanism to the wheelchair.
Fixed Vs Foldable wheelchair
Now that we figured out the problem, we went ahead and researched existing wheelchairs with a similar mechanism. After research, we found that none of the existing models were made using mechanical actuators. Though operating this would be difficult as it requires a lot of physical effort (as compared to pneumatic and hydraulic actuators), this was much more cost-effective and fit right with our motivations.
Here are the components that we designed on Solidworks.
1) Base and Upper plate
2) Lead Screw
3) Nut
4) Link
5) Connecting Pin
We then assembled them to get the complete mechanism as shown in the image which was later exported to ANSYS where we simulated different loading conditions.
Assembled Mechanism
The whole point of this project is to create a height-adjustable, detachable handle wheelchair which is affordable to most people. We decided to just work on the mechanism and links and attach it to an existing wheelchair. So our focus here is to choose a material for the lift mechanism that is strong so as to withstand the load and is considerably cheap. Primarily, the connecting rods and links must be made of really strong material as most of the load is directed on them. Considering our requirements and tradeoffs, we decided to use mild steel. Sheets of coated steel and mild steel were cut into the required shape using a cutting machine. These were then folded to the designed shape using the hand press machine. We have used Arc Welding to connect the scissor links and MIG welding (CO2 gas) which is essentially a welding process that uses a continuous solid wire electrode heated and fed into the weld pool from a welding gun. We attached the scissor lift mechanism to the wheelchair by using MIG welding. After that, we placed the seat cushions on the top frame. We also cut down the handles on the right side and made them detachable.
1) Learned how to manage stuff with the limited time and resources available.
2) I was able to integrate my UX skills with my mechanical knowledge and create a feasible, patentable product.
3) I learned effective management skills where I split the project into parts and allotted work equally to teammates to finish it on time.
4) Presenting a full-blown project report was something new to me and I had the chance to do it in front of the review board.
Right now as the wheelchair is rigid and unfoldable, it is very difficult to carry it along in a car. But the mechanism itself (both the scissor lift and removable handle) is feasible. We have also applied for a patent for the mechanism. In the future, we may work on how to apply this to foldable chairs.
Other Works
