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06.01.2000
Wheelchair Riders in Control
WWI's Model of Technology Transfer
by Peter Pfaelzer, Ph.D. and Marc Krizack, J.D.
(This article is a
summary of a more extensive article on technology transfer currently in
progress. (Comments and suggestions solicited; please send to: WWI Program
Director Dr. Peter Pfaelzer at pfaelzer@sfsu.edu,
or by fax at 415-338-1290.) NOTE: In this article, Whirlwind's design process is described as being "Descriptive Design." Although Whirlwind continues to design and test through multiple design prototypes, we are now heavily using CAD in our design process. For an update on our design process see Whirlwind-SolidWorks-AMD. The remainder of this article retains its relevance.
When Ralf Hotchkiss
began designing wheelchairs in Latin America in 1980, there was no one
else designing state of the art wheelchairs at a low cost for active use
in developing countries. Today, there are at least four other non-profit
organizations promoting wheelchair production around the world. Yet Hotchkiss's
model, since expanded and now institutionalized at Whirlwind Wheelchair
International, remains unique in its approach. For unlike other organizations,
WWI ascribes to the wheelchair rider -- as designer, trainer, mechanic,
tester, and even marketer -- the central role in the technology transfer
process. This model has made the Whirlwind Network of independent wheelchair
producers the highly productive source of new ideas in wheelchair design
that it is today.
Design Methodology
The most common design methodology used in modern manufacturing today
is the prescriptive design process. This methodology is characterized
by a multi-step linear process of problem formulation, idea generation,
and prototype production. It presumes that most significant relevant information
and resulting solutions can be learned prior to production, and it relies
on highly educated experts in every stage of a centralized design process.
The prescriptive process is employed to minimize the risk before large
amounts of capital are invested in the production of costly prototypes.
The process itself requires the expenditure of significant amounts of
capital.
Prescriptive Design: The time and money
spent on problem formulation and ideation prior to prototype construction
may reduce the number of prototypes necessary to produce a successful
design. |
WWI's design methodology
is based on a method more common in small business known as the descriptive
design process. This process was the primary design process utilized prior
to the turn of the century when engineers learned their craft on the shop
floor rather than at specialized technical colleges and universities.
In contrast to the modern engineering prescriptive design process which
requires a substantial amount of early work on paper or the computer,
the descriptive process is characterized by the early production of a
prototype. The design is refined through repeated prototype/evaluation/prototype
cycles. The designer learns about the problem through the generation and
evaluation of sequential prototypes.
The descriptive process relies to a large extent on the craftsperson in
a more decentralized design process and may require more prototyping cycles
than the prescriptive method. However, for a product like a wheelchair,
that can be prototyped quickly and inexpensively, the descriptive design
process is efficient and cost-effective. For WWI, use of the descriptive
design process derives naturally from the socio-economic situation in
developing countries and from the complex nature of disability itself.
Descriptive Design: Numerous prototyping
cycles are required to refine the design, but this method can be effective
when prototypes are built quickly and inexpensively. |
Unlike general product
design, which is aimed at the population at large who within a certain
range can all be accommodated by a single design, product design for people
with disabilities is difficult because it requires multiple solutions.
A wheelchair is not merely a chair with wheels. Different wheelchair riders,
even with the same nominal disability such as paraplegia, quadriplegia,
multiple sclerosis, cerebral palsy, or post polio, can have widely different
ways of sitting and pushing which need to be considered in the design
process. The mobility equipment needs of disabled kids also change as
they grow. One only has to look at the wide range of wheelchairs available
in industrialized countries to understand fully how complex designing
for disabilities really is.
What Difference Does the Setting Make?
The design problem is made even more complex for designers of mobility
equipment in the developing world. As a matter of course, wheelchair design
must also include consideration of diverse uses and geographical conditions.
Wheelchairs can be for indoor use, outdoor use, long distance travel,
urban use, rural use, and quite often must function well in dirt, in mud,
in fields, on gravel, through bomb craters, etc. WWI's wide rubber caster,
known as the "Zimbabwe Wheel," is the result of design for the
most rugged conditions.
The absence of even the most basic accessibility in the architectural
infrastructure and public transportation must be considered in the design
process. As an example, the extremely narrow bathroom and elevator doors
in Russia gave rise to the Siberian wheelchair frame which can be narrowed
by the rider while sitting in the chair.
Cultural factors can also affect wheelchair design. In many countries
in the Near East and Asia, for instance, much social activity, including
cooking and eating, occurs at floor level. Wheelchairs in these settings
must be designed to allow the rider to participate in these activities.
The newest Whirlwind allows some users to sit near the floor by incorporating
a jump seat at the level of the footrests.
Wheelchair design must also take into consideration such factors as the
type of toilet facilities available, which can often be little more than
a hole in the ground or floor. The wheelchair rider/builders in the Whirlwind
Network wish to achieve the greatest degree of independence, mobility,
and social integration possible. Thus, their wheelchair designs must be
capable of responding to these multiple needs. The prescriptive design
methodology, working as it does at some distance from the wheelchair riders
in developing countries, is unlikely to produce the range of solutions
necessary to answer these local needs.
Wheelchair design in developing countries is also limited by cost considerations.
Because most people who need a wheelchair cannot afford an imported one,
low price is a primary design criterion. The two main ways of keeping
wheelchair prices low are through low initial capitalization of wheelchair
shops and by the use of materials readily available where the wheelchair
is to be built.
All plant and equipment costs must be amortized and included in a wheelchair's
retail price. When initial capital funds are borrowed, the cost of repaying
the loan must be included in the chair price as well. Low per shop capitalization
costs make it easier to raise start-up capital and establish more production
facilities. These multiple producers can form a competitive marketplace
for wheelchairs keeping quality high while forcing prices down. At the
same time these producers can act cooperatively, each becoming part of
a design network. This is how the Whirlwind Network came to be.
The use of readily available materials is necessary to keep costs low
and ensure that the chair will be locally repairable. For Third World
wheelchair design this often means that a single model will have multiple
design variations.
Even within a single country, political and economic factors can either
limit the availability of existing materials or create a situation where
previously costly materials become available and affordable. The placing
or lifting of trade barriers to the importation of bearings, for example,
has had a big impact on the design of wheelchairs. In Africa where bearings
were too expensive, WWI designed roller bearings using steel nails or
welding rod. In 1983 in Nicaragua, the price of acetylene used in welding
skyrocketed as a consequence of the Reagan administration's economic embargo.
Wheelchair rider Omar Talavera responded by designing a caster fork made
from a single piece of bent steel rod that did not need to be welded.
Although only meant as a temporary innovation, it nonetheless kept the
price of caster forks affordable until the embargo ended and the cost
of acetylene dropped. The lesson is that wheelchair designers must be
capable of producing rapid solutions as the local availability of component
materials changes.
Wheelchair Riders Integral to Design Solutions
Historically, these many needs have been best understood and dealt with
by wheelchair riders involved in every aspect of a continually evolving
design and production process. WWI at San Francisco State University nurtures
this process by acting as the hub of a network of wheelchair builders
now spanning more than 25 countries. WWI's role is to energize and extend
the network, promote and coordinate activity, serve as the communications
center, and stimulate and cross-fertilize the design process. The WWI
design teams have always included at least one wheelchair rider. Our wheelchair
rider-designers use the chairs they design during their daily activities
to understand exactly how they perform in real conditions.
Both at San Francisco State University and around the world, WWI wheelchair
building courses always include a significant number of wheelchair riders
among the training participants. These participants become active collaborators
in the design process. They ensure that WWI is kept aware of all the factors
which affect their real mobility needs and often provide the design answers
themselves. We term this process "Collaborative Design."
Phillipe Mazard (Handicap International,
France) discusses marketing schemes with David Mukwasa from Disacare
(Zambia). |
Although theoretically
there is no reason why wheelchairs can't be built exclusively by non-disabled
designer/mechanics relying on information supplied by wheelchair riders,
the reality is that very few non-disabled persons fully believe and understand
what people with disabilities say, even about matters which a disabled
person can be expected to know most.
Wheelchair designs, once translated into prototypes, must be tested. WWI
uses inexpensive shop floor strength tests and obstacle course performance
tests to simulate real conditions. But the only way wheelchairs can be
tested under the full variety of actual conditions and for every conceivable
purpose is by wheelchair riders who use the chairs every day. Over time
wheelchair riders provide the feedback which is essential for going to
the next level in the design process. They have the added benefit of a
good wheelchair during this evaluation process, and unlike the evaluation
process in the prescriptive design method, the cost of testing and evaluation
is minimal and design changes can be made rapidly.
The involvement of wheelchair riders in wheelchair design and production
also affects the technology used in wheelchair building. Many of the wheelchair
riders we train have only basic mechanical experience and little formal
schooling. Production methods and training techniques must be kept simple
to facilitate the training process. The practical strength tests and obstacle
courses, along with the use of full-size drawings, pictures, and similar
techniques facilitate the participation of people who by and large are
without formal advanced educations. We have sometimes learned this the
hard way. Ten years ago WWI abandoned a nicely compact footrest design
whose compound angles were so difficult to bend properly that even the
trainers wasted a lot of time and tubing trying to get it right.
Marketing
Advocates
A critical area in which wheelchair riders can play a decisive role is
wheelchair marketing. Because most wheelchairs in developing countries
are purchased by government and private charities rather than the end
user, the wheelchair rider/consumer has not had the ability to influence
quality and price to the same extent as purchasers of general consumer
products. But wheelchair riders can play an effective role in gaining
increased government funding for good quality, locally built wheelchairs.
In Novosibirsk, Russia, activists from the Finist (Phoenix) Disabled Sports
Club demonstrated the Whirlwind wheelchair made in Novosibirsk to government
officials in charge of wheelchair purchases. They made these officials
realize that wheelchair riders are the real experts when it comes to wheelchairs,
and they educated the officials about the Whirlwind's advantages for active
use. That effort led to a government order for 500 Whirlwind wheelchairs.
Wheelchair rider/advocates also play an important long term role in developing
the wheelchair market. The removal of architectural barriers and the increase
in accessible transportation open up new opportunities, especially for
people with more significant disabilities. This will create a need for
improved wheelchairs so that, to paraphrase Star Trek, they may go where
no wheelchair rider has gone before.
Conclusion
The most efficient use of development funds for promoting the design and
production of wheelchairs in developing countries is through a decentralized
international network of small to medium sized production shops, coordinated
through a central hub which facilitates communication and collaborative
design through newsletters, wheelchair design congresses, technical exchange
visits, web pages, and other means. Most importantly, because someone
has to be responsible for making the difficult choices involved in balancing
design features against cost, the wheelchair rider, who knows the problems
best and is most affected by the prescribed solutions, must play the leading
role in wheelchair design.
The authors wish to thank Joan Rogin for her contributions
in both the conceptual and editorial phases of this article.
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