The Design Process - Medical Device Design: Innovation from Concept to Market - page 28

measure measure

Input Output

ÒdesigningÓ

Input Output

Figure 3.1
Design as an open
loop control system.

feedback

Figure 3.2
Design as a closed loop system.

Catherwood, 2005 ). There is no reason why we should not form the same connection. That
is why I introduced the closed loop example to demonstrate the need to measure input and
output (etc.); the requirements to enable feedback; and the need to understand the process, so
that ultimately we can control our design system .

However, we are very lucky as we are able to define our system; we are able to define the
process . If we do this correctly we will be able to implement the concept of DMAIC and,
ultimately, we will control our design process.

It's not all plain sailing. Anyone who has been to a concert and heard the scream from the
speakers when a microphone is poorly placed will know the detrimental effects of feedback.
To control our system we need to understand it, understand how it responds to changes
in data, and understand what “makes it tick,” Hence, to understand the design process is
fundamental in our task to control it.

It should be apparent that I have proposed and highlighted the need to control our design
process. In order to control it we need to define it. Subsequently we must measure and
analyze the results (input and output). In this way we are able to continually improve . No
wonder Six Sigma picked the letters DMAIC out of the alphabet.

The other thing to remember is that the design process is an iceberg ( Figure 3.3 ). Most of
an iceberg lies under the water, where it is hidden from sight; so it is with design. Everyone
sees the tip of the process. Imagine a brand new, shiny Ferrari - how many people think,
when they see that lovely new Ferrari, “Ooh there was lots of work done on the calculations
for the strength of the fan belt” - not many! They will all look at the color, the upholstery,
the wheels, the engine bay, and the logo. They will not see all of the hard work that lies