Kyaro Assistive Tech
Learning Goals
Working on a tight budget
Mechanical Design
Using analysis to inform design decisions
Skills Developed
Iterative and Team Design
CAD/FEA
Working Under a Contractor
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Year
2024
My Role
Project Manager/ Designer/Fabricator
The goal for this project was to develop a tilt in space wheel chair that could be used and built in Tanzania by Kyaro Assistive Technologies for under $70.
A tilt in space wheel chair is one that allows the user to recline, in our case up to 45 degrees, without moving the center of gravity enough to make the chair unstable. The tilting function is important for users where spinal compression needs to be limited or actions like swallowing are difficult.
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Most available tilt in space wheelchairs are easily over $1000 dollars and require lots of high end machinery to fabricate. In our case we we're limited to $70, hand tools, a drill press, and stick and mig welders.
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For our prototype we choose to use a four bar slider linkage. This allowed us to keep the movement of our center of gravity minimal without the complex geometries typically used in tilt and space wheelchairs.
The translation of the center of gravity with a pivot at the back of the seat.
The translation of the center of gravity with a pivot at the back of the seat and our slider mechanism acting to counteract the displacement of the center of gravity in the x direction.
When deciding on the lengths of our linkages we used MATLAB to simulate the sliding motion and then parameter swept through our possible linkage lengths to determine the lengths that minimized the movement of our center of gravity. Visual representations of the movement of our center of gravity are to the left.
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Using Tanzanian stock pricing we were able to build our wheel chair for $44.84. The chair worked as intended with a few tweaks needed to base in order to increase stability. More details about the project can be found on the project website here.
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Working under a tight budget and with limited tooling was a fun challenge and created lots of areas for problem solving. For this project I focused on using analysis to reinforce my design designs and find redundancies in our design in order to lower cost and weight. I was also focusing on designing for manufacturability, specifically minimizing the importance of tolerancing as the the stock in Tanzania has much more variance than it does in the US.
An exploded isometric view of all the parts we designed to integrate our tilt in space mechanism to Kyaro's existing wheel chair base.