A Slam-Dunk Design for a Wheelchair

When they were students at the University of Illinois, Ricky Biddle, Eric Larson and Ben Shao decided to do something for the disabled athletes involved in wheelchair basketball. This sport is inherently dangerous, and injuries resulting from collisions are frequent. The other intrinsic problem is the need for participants to use hands not only to dribble the ball but to control the wheelchair. So the three chaps teamed up with Austin Cliffe, another designer, and have come up with a prototype Balance Sport Wheelchair, now Gold winner of the 2008 International Design Excellence Awardin Medical & Scientific Concepts category.
Ricky Biddle gave us the following explanation:

The design solution uses a braking system that is activated by the user’s movements in an intuitive way. To turn, the player leans in the desired direction. To stop, the player simply leans back.

Every athlete is different. Add a wheelchair to the equation and these disparities multiply exponentially. On top of size differences, personal preferences and so on, wheelchair athletes also have different injuries and unique challenges and mobility limitations associated with their injury. This meant designing a solution that would meet the needs of people with varying levels of skills and abilities.
After testing simple mechanisms and methods of braking, it became clear that the brakes and the leaning mechanism would have to be extremely flexible and be able to be tuned to accommodating the various needs and preferences of players. Disc brakes allow for adjustability that is as simple as turning a dial and for independent adjustment of the left and right wheels. The disc brake system isolates most of the contributing variables of what could be a complicated braking system into two small, easily adjustable units.
The designers spent a great deal of time and effort addressing the points of rotation to find the optimal ergonomic solution. In an attempt to aid players with mobility only from the shoulder up, the left-to-right point of rotation was placed at the middle of the back in prototypes, but it quickly became apparent that this solution was too sensitive. A very slight lean could cause the brakes to engage suddenly, and players with limited means to control their leaning would be jostled around in a jerky turn. What should have been one smooth action became several shorter brake, brake, brake motions. After many attempts to dial this in, it became apparent such a short throw was more of a detriment than an aid to players with low mobility. We observed that left-to-right leaning by athletes with greater mobility involved a shifting of weight from one buttocks cheek to the other. This resulted in a linkage type of rotation, rather than the one-point center rotation that we had considered. We placed two pivot points under the seat. The longer throw also results in a less touchy mechanism, giving players of all abilities a smoother lean/turn braking operation. Two points of left and right rotation add further to the adjustable resistance of the leaning resistance.
The leaning of the seat back to actuate the brakes also allows for adjustable resistance for athletes of different abilities. Player with little mobility can set a high resistance of their seat’s lean and adjust their brake resistance to allow very slight movement to give them the desired braking and turning response. Players with more mobility, on the other hand, may prefer a looser setting to allow their upper body to move more freely and fluidly without inadvertently braking or turning.

source: http://www.medgadget.com

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