Vol. 1, Issue 3 -- December-January, 1996

PDS, A Tool for Creativity and Compromise

by Jane Fee

In the last issue of The Innovator, we talked about the research process. This article will carry the "research process" a step beyond conceptual design. The physically challenged consumers on the design teams have very definite and creative ideas about the design of devices and so do the rehabilitation engineers. However there are instances when two or more of these creative ideas are in conflict. One approach to resolving such conflicts is the development of a list of Product Design Specifications (or PDS) which is used to prioritize ideas and eliminate incompatabilities. Discussion and agreement on a PDS list by all members of the design team is very important.

The Producd Design Specifications list defines what a device must be able to do. The specifications start with a "wish" list and a "need" or demand list. The demands on the list are what the device absolutely must do, while the wish part of the list is just that, what you would like the device to do. In order to produce a PDS list that has realistic "wishes" and demands compromises must take place. This is necessary because wishes and demands may conflict with one another, such as keeping the product inexpensive verses using a particular high quailty construction material. Compromises in designing any device must be well thought out and possible to build with current day technology. Lets use the compromises that came up on the design of the Auto- Vac as an example.

On the PDS list one demand was dry cleaning coupled with a wish that the device could vacuum both dry and wet cleaning. For the Auto Vac to be able to accomplice both dry and wet cleaning, the weight of the over all vacuum would have to be double of what the weight turned out to be.

Another demand was to have the standard feature of the vacuum adjusting to different types of floor surfaces and the wish was that the attachments must be completely accessible so that the vacuum could clean furniture for example. This wish was compromised when the expense of the technology required for each attachment to be intergrated into the interface system became prohibited.

On the other hand, sometimes wishes on the PDS list become demands through research of available technology and practical testing of the vacuum prototype by the consumers on the design team. Originally, this wish was "provide separate switching for drive motors and vacuum motor to save battery life when driving to location of use." In researching available batteries on the market today and juggling the problems of battery life, weight, and cost it became apparent that separate switching was necessary. So this wish was changed to a demand on the PDS list by the group. Another example of a wish becoming a demand came directly from the consumers on the team. The consumers after trying out various methods of handling regular vacuums decided that a remote controlled system was the best way to make the vacuum accessible While experimenting with different types of interfacing, it was discovered that it was a relatively easy engineering matter to get the desired direction of movement by the vacuum of forward, backward, rotate left, and rotate using a standard joystick in this case. This part of the operation of the vacuum was thus changed on the PDS list from a wish to a demand.

Sometimes the wishes of the disabled consumers on the team, for the product that is being designed is not viable or practical from an engineering point of view. The engineers on the team help the consumers keep the design of the product, in this case, the Auto-Vac realistic. One demand on the PDS list was "no adaptations of home required", while one wish was "perform some autonomous cleaning". The engineers pointed out that in order to have the Auto-Vac "perform some autonomous cleaning" each home would have to be adapted to some type of sensors that the Auto-Vac could "read" in order to perform its required task. This was in conflict with the afore mentioned demand, so this wish was given a low priority.

All of the above examples show how compromises can be made while preserving the creativity of the ideas generated in each design team through the give and take of the consumers and the rehabilitation engineers. This bodes well for the creation of new designs and new devices for the physically challenged consumer.