Page 491 - Biomedical Engineering and Design Handbook Volume 2, Applications

APPLIED UNIVERSAL DESIGN 469

Countertop or
Pan/Tray cabinet bottom

Human force to open Human force to open
Human force to Human force to
place food place food
Human force to close Human force to close
Human force to Human force to
Bake, broil or toast foods
adjust settings adjust settings
to proper doneness at a
customer specified
Electricity temperature without Heat
burning any food or the
Cold food risk of fire. Oven to be Hot food
accessible to all possible.
Stove at correct Stove at correct
temperature? temperature!

Food cooked? Food cooked!

No fire? No fire!

Energy flow

Legend Information flow
Material flow

FIGURE 16.7 Overall system diagram, toaster oven example.

The legend shows lines with arrowheads for energy, material, and information flow. Anything that
does not remain in the toaster oven must be shown to leave. For example, food is considered a mate-
rial flow. It enters cold and then leaves hot. The design team can then brainstorm ways to go from
cold to hot. An example of information flow is “No fire?” and “No fire!” The question mark desig-
nates that we need an answer. The exclamation point tells us that we have an answer. Once again,
the team will brainstorm, this time searching for methods of preventing fires due to grease, etc.
The overall system diagram is reduced to subfunction diagrams. Figure 16.8 shows four of the
subfunctions. These shall be further subdivided as necessary. These diagrams allow us to separate
each function of the product for individual and thorough consideration. Subfunction 3, for example,
notifies the cook when the oven is preheated. How will this be accomplished? Tone, light, speech
synthesizer, flag, or LED display? Table 16.4 is designed to heighten awareness of sample input and
output devices used by persons with disabilities. Ideally, the product should suit all cooks, including
those with disabilities. At times, appropriate jacks need to be designed into the product so that spe-
cialized input-output (I/O) devices can be used. For example, a person with a hearing impairment