Tuesday, July 29, 2008

Wheelchair Project

This is actually an older project for those I've talked to over the last year or so, but it's worth a mention nevertheless.

This job came to me from folks in Physical Medicine and Rehabilitation. They had a wheelchair-bound patient who was an expectant mother. An c-spine accident many years ago had left her with no use of her legs and only limited use of her arms and hands. She used a powered wheelchair to get around. The OT wanted us to build an attachment for her wheelchair that would position her infant front and center, facing her, and within easy tickle reach. The idea was for the mother and child to have much more frequent and intimate interaction than they otherwise would have.

We scratched our heads and, after some time, came up with something that fit the bill. We bought a second-hand infant car seat and attached it to an adjustable metal frame that attached to the side of the mother's wheelchair. The car seat was a handy shortcut, since we knew it would be reasonably comfortable, had integrated restraints, and is generally tested-to-death for safety (technical term). It also cost $35. The adjustable frame required some cleverness, if I do say so myself, to permit the different adjustments we would need, but balanced against the need for convenience, adaptability, and light weight. The caregiver would need to be able to quickly attach and detach this thing and adjust the position.

The extruded bar at the base is the only part permanently-attached to the wheelchair. The frame can slide forward and back on that extrusion; or slide all the way off, so that the device can be set aside. The parallel linkage can raise and lower from nearly horizontal to nearly vertical in 10-degree increments. The infant seat can pitch forward and back on the cross bar +/- 22 degrees from its normal position. Naturally, there are hard stops for all of these adjustments, so that nothing can fall apart.

I could delve into the finer details about laser scanning parts of the infant seat to get it into the computer, or running simulations on the strength of the frame, or making rapid prototypes of some of the parts to ensure the fit would be correct, or scrambling to meet a deadline to getting this work accepted to a conference, then scrambling to make a poster in time for that conference, but I'll not bore you.

The purple color was the patient's choice. No, they aren't Vikings fans - they just like the color. The project's worked out pretty well so far. The only hitch is that the kiddo is getting a little too rambunctious to tolerate sitting in the thing for very long, and will outgrow it before much longer. That's just as well - there is another patient, a wheelchair-bound expectant father, that will get it next.

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