As a part of the Human Centered Design class I took in Fall 2020, I participated in a semester long project with my team, Meals & Wheels to develop a product to address the challenges of cooking for wheelchair users.
Cooking is an activity that brings comfort, relaxation, sustenance, and fun for people of all ages and backgrounds. For wheelchair users, however, cooking can be a tedious, unsafe, and ultimately inaccessible activity.
Wheelchair users navigate the kitchen at a lower height when seated and often with diminished core strength. These factors contribute to many difficulties when moving hot and heavy pots and pans from elevated surfaces like a stove to lap-height and vice versa. With the lap serving as a makeshift staging area, wheelchair users often have to deal with additional complications like burns and spills.
Wheelchair users need a solution that allows them to easily move hot and heavy objects from lap to stove/sink height safely.
We worked with 8 wheelchair users who helped us gain insight into common pain points in and around the kitchen. Some of the most notable insights gained centered around the use of cutting boards on the lap to carry and stage items, how the lack of core strength affected how users maneuvered items, and how the height of countertops posed issues with accessibility and leverage. The pictures below represent some of these ideas presented during our virtual interviews.
"40-50% of my kitchen is inaccessible to me"
"Everyone gets burned eventually… it’s a rite of passage"
"Moving a pot of boiling water is nerve wracking for me, because I’ve had friends who’ve burned themselves without noticing"
With these research insights in mind, we converged on a specific product opportunity gap (POG) that we wanted to address. How might we help wheelchair users safely move kitchen objects filled with boiling liquids to and from countertops and user-range heights?
We performed a value opportunity analysis to determine our top product requirements:
Safety: This product can withstand high heat and remain stable enough to prevent splashes and spills
Independence: This product must not require assistance to use or to set up
Work for a range of strengths: This product can lift from different heights and does not strain mobility
To finally begin the process of conceptualizing solutions, we generated nearly 100 different concepts to address our POG. We then filtered these concepts by organizing them into similar categories and narrowed down to ~20 concepts by eliminating for redundancy and feasibility. We utilized dot voting to converge on our top four concepts which we made into low fidelity prototypes.
Four Bar Lift Counter Lift
Side Lift Trolley
These prototypes were then used to obtain feedback from users in second round interviews. From this feedback we selected the Four Bar Lift design for its compactness and versatility.
Since I was not in Berkeley but my teammates were, it was agreed that I would make the design and CAD and they would meet to assemble it as well as show it to users to obtain further feedback.
The four bar design was one of my original concepts from our concept generation phase. The four bar mechanism is nice because the platform will always remain level to the ground if the links are parallel. Additionally it only requires one degree of freedom to actuate (i.e. only one link needs to rotate to raise and lower the platform) The original design had intended for users to slide objects on and off from the front. However, the low fidenlity prototype was tested on an office chair so it failed to accoutn for how much space the foot rests occupied in front of the wheelchair. I spent a lot of time trying to think of ways to overcome that distance while still allowing the platform to return to the lap. My many sketches from this process can be seen in the image below.
Fortunately, through user interviews, I came to the realization that loading and unloading from the front was impractical because users would have to lean quite far foward to do so, which can be difficult with a lack of core strength. Typically, many wheelchair users will load and unload objects from the counter onto their lap from the side because they cannot get close enough from the front. This helped me realize that loading and unloading from the side would be easier for users and for me to design.
With this design in mind, I began on the CAD which had to be quite detailed and well thought out because we only had two weeks to complete the project and with COVID limit access to tools, it was unlikely that we would get to make a second iteration. Because of these constraints, I chose to design the part to be laser cut out of 1/4" plywood, which was cheap and would be easy to make modifications with hand tools if needed. Wood was unlikely to be stable enough for large pots, so it was decided that this prototype was meant to validate the form factor and how it would be used rather than for structural stability.
The design utilized shoulder screws at the joints with washers and laser cut spacers to ensure everything was spaced appropriately. The holes for the shoulder screws in the wood were laser cut at a smaller diameter then reamed to size to ensure the hole wasn't tapered and to attempt to reduct friction in the joints since bearings weren't used. The top platform was a separate part, meant to be screwed on separately. The platform was extenable on both sides with hinged handles that folded up and down using butler hinges. Because I did not have access to the wheelchair my team had borrowed for this project, designing the mounting system was tricky. I designed some 3D printed clamps and put slots in some of the holes to allow for variability in some of the wheelchair dimensions.
Overall there were some issues with the assembly with regards to mounting but a second iteration was not needed for this fidelity to demonstrate to users the form factor of the device.
Our top priorities in the near term are to improve the strength and stability of the platform. Our current wooden platform served as a proof of concept from a UX perspective which demonstrated that the four-bar platform can effectively allow wheelchair users to move heavy and hot objects from high-to-low and vice versa. By transitioning to a stronger material, creating more stable joints, and adding additional support across the platform, we hope to avoid any wobble during the lift and fall of the platform. We may also utilize another motor to increase the strength of the platform to allow for larger and heavier loads.
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