Accessible PlaySeat

We built a play seat for a three-year-old who loves Formula 1. The first time he sat in it, we learned the wheels were in the wrong place.

Role: Seating structure, fabrication
When: September – December 2024
Team: Team P-Play, 4 people · EGR 101
Advisor: Dr. George Delagrammatikas

6 / 6

requirements verified, 1 by proxy

15.72 lb

against a 20 lb target

weeks, concept to delivery

4 ft

highest drop test survived

10 ft / 20 s

mobility target, met on every surface

0.6 in

largest gap allowed

The finished PlaySeat outdoors: a padded seat with a five-point harness on a white base, a clamp-on tray, a large three-spoke side wheel, and a black faux carbon-fiber front wing over the leg padding. — **Fig. 1**The finished chair, with its clamp-on tray.

Timeline: 11 weeks, concept to delivery
Verification: Fit test with client and caregivers; six pass/fail tests against target values, one by proxy
Change from testing: Drive wheels moved forward, rear casters added
Weight: 15.72 lb (target 20 lb or less)
Materials: Polycarbonate base, acrylic spoilers with carbon-fiber vinyl, 3D-printed PLA cane mount
Processes: Laser cutting, acrylic bending, manual machining

01Who it was for

A three-year-old with spinal conditions needed more upper-body support than any wheelchair on the market gave him, and without it he couldn't play with the other kids in his classroom. We had eleven weeks to find out what he and his caregivers actually needed, turn that into requirements we could measure, build to them, and test every one.

The chair had to let him reach the ground to play with toys on the floor, right himself after leaning, move on his own and get over obstacles, keep up with his peers, and be something he actually enjoyed sitting in.

02What was mine

I designed and fabricated the seating structure, and shared requirements elicitation and verification testing with my teammates Anna Karius, Ethan Liao, and Julia Morgan.

03From sketch to fit test

We brainstormed about twenty concepts, cut them down to six, and scored those in a weighted Pugh matrix where mobility counted the most. Solution 8 won with 4.65, against 3.7 for the next best: a race-car seat whose bottom snaps in, with an adjustable headrest, a folding cane, and a lap tray.

Hand sketch of Solution 8: a race-car style seat with a spoiler, an adjustable headrest, a foldable cane, and a seat that snaps in. — **Fig. 2**Solution 8, the one we picked.

Hand sketch of Solution 12: an upright chair with two support straps, a removable leather seat, and large wheels. — **Fig. 3**Solution 12, the runner-up.

Pugh matrix scoring six solutions on mobility, weight, durability, adjustability, aesthetics, and ease of cleaning; Solution 8 scores highest at 4.65. — **Fig. 4**Our Pugh matrix. Mobility carried the most weight, at 0.3.

Prototype #1 was cardboard, and #2 was the first real chair. Between them they showed us a weak wheel connection, a spoiler that was too long, wheels that were too small, a seat base that was hard to get out, exposed metal, and missing casters.

Cardboard mock-up of the seat with a tall back, cardboard side wheels, and a flat base. — **Fig. 5**Prototype #1, in cardboard.

The second prototype: a white booster highchair with a patterned seat cover, a tray, and a large side wheel, on a lab bench. — **Fig. 6**Prototype #2, the first real chair.

We started from a booster highchair with a removable base and built around it: a five-point harness and foam padding for support, side wheels he can push himself, front casters so it turns in place, a cane attachment so caregivers can push him, and a clamp-on tray. He loves Formula 1, so we also gave it a faux carbon-fiber spoiler and front wing. Not looking like medical equipment became one of our requirements.

A prototype fit test, our first validation against the real user, showed he couldn't reach the push rims. We'd written that requirement down and still gotten it wrong. We moved the drive wheels forward, which fixed the reach but shifted the center of gravity, so we added rear casters to balance it. That's why the final chair has casters front and back.

Close-up side view of the final chair's large three-spoke wheel, footrest, and small front caster. — **Fig. 7**Three-spoke side wheel he propels himself, and a front caster for turning in place.

Rear view of the chair: a black faux carbon-fiber spoiler bolted across the seat back, and a grey mount holding a black cane. — **Fig. 8**Rear view: the faux carbon-fiber spoiler and the cane mount.

04Testing every requirement

We verified the finished chair against every requirement with a target value. All six passed: five directly, and durability by proxy, since two years of service can't be tested in eleven weeks. We delivered the chair to the client at the end of the build.

The finished chair parked next to Duke Motorsports' Formula SAE car, number 63, with a helmeted driver in the car, outside Duke's engineering buildings. — **Fig. 9**The finished chair next to Duke Motorsports' car 63. He loves Formula 1, hence the wings and the spoiler.

Criterion	Target	Test	Result
Safety	No reachable gaps of 0.6 in (15 mm) or more	Measured every gap he could reach	Pass None 0.6 in or larger
Support	Holds his head 80–100° from the ground	He leaned away from vertical and tried to return upright	Pass Stayed upright
Mobility	10 ft or more in 20 s	Pushed across carpet, tile, concrete, and over toys	Pass All surfaces
Aesthetics	A rating of 4 or more from him	He rated it on a scale he set himself	Pass 4, and visibly enjoyed it
Durability	2 or more years of service	Verified by proxy: drop tests up to 4 ft, the most severe case we could run in 11 weeks	Proxy Survived every drop. Service life itself was not tested.
Weight	20 lb or less	Crane scale	Pass 15.72 lb

A black cane clamped into a grey 3D-printed mount on the back of the chair. — **Fig. 10**The cane attachment lets a caregiver push the seat…

The same mount with the cane lifted out, showing its two metal clamps. — **Fig. 11**…and lifts out of its printed mount.

Team poster titled Creating an Accessible Seating Solution, with sections for motivation, project goals, design blocks, the final design with labeled features, the design criteria and testing table, conclusions, and acknowledgements. — **Fig. 12**Our final poster. Click to read it full size.

05Looking back

It's the smallest project here, but it taught me the most about requirements. Until we put him in the chair, ours were really just educated guesses. It also taught me to be upfront about what a test shows: a drop test can stand in for two years of use, but it doesn't prove it, so the table says "proxy" instead of "pass."

The next change would be foam inserts that come out more easily, so the seat can be resized as he grows.

06Skills

Requirements elicitation
Requirements decomposition
Verification testing
User testing
Ergonomics
Laser cutting
Acrylic bending
Manual machining
Teamwork

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