Even though it feels kind of weird for me to describe Amber in a purely medical context in this post, it's probably the best way to do it so that others can understand fully how to make a harness like this if they have the same issues.
Due to the combination of spastic cerebral palsy, untreated scoliosis and just normal body mechanics, when Amber is driving in her powerchair, her upper torso begins to tilt toward her right side. Within a minute or so, she is tilted so far that it is painful. She has to make frequent stops to sit back up straight.
Her wheelchair seating specialists delivered a special seat with a built-in leg abductor wedge and harness. The leg abductor lifts the knees slightly and spreads the legs a few extra degrees. This adds a little extra seating comfort and gives some added stability. The problem though, is the harness. It's crap and I figured I could make a better one.
The current harness, which is shaped like an X, goes across the shoulders and waist. The idea looks sound but the problem with it is that it's made of a very springy fabric coated rubber which means there is a lot of give to it. Also, the buckles and straps are far too complicated for untrained personal aides to connect and adjust properly. The end result is that everything soon becomes loose on the bottom, which means the top starts to constrict her throat while she starts to lean. Do you see the problem here? Even when it is adjusted properly, she is unable to sit forward to reach train and elevator buttons or use her key card get in her apartment.
If I recall correctly, the bill for this contraption was near $5000.
The custom harness that I made for her completely stops her from leaning to the right while still allowing her to intentionally lean forward and to the left. All it took was a quick visit to REI and the Wal-Mart crafts department and an hour of time to put all the assorted tidbits together. Total cost was around $8.
In short, it is a simple strap and buckle system that wraps completely around her upper torso, under the armpits and above the breast line, It is attached to the chair in one place only, behind the left side of the chair. This allows much more movement in all directions except to the undesired right. The strap that goes under the right armpit is cloth padded for comfort. There is a single quick-release buckle in the front. Unlike the professionally made harness that needs to be adjusted each use, my harness is adjusted only once and never needs adjustment again (unless the person gains or loses a lot of weight.) For those who are also conserned about looks, the strap looks professionally made, no matter who puts it together.
If you are interesting in specific instructions for how to put it all together, drop me an email and I'll forward them to you.