Page 585 - Design for Six Sigma a Roadmap for Product Development

542 Chapter Fifteen

Ideal function
y=
Braking
torque Actual
relationship

M=Foot
force

(a)

Ideal function
y=
Braking
torque
Actual
relationship

M=Foot Figure 15.6 Actual relationships
force between foot force and braking
torque. (a) Not robust, (b) robust.
(b)

1. To make sure that the main transformation (in the car brake case,
it is an energy transformation process) process of the high-level
function (stopping or slowing down the car) can perform robustly at
different magnitudes of transformation.
2. To make sure that the brake system has excellent controllability for
this transformation process; this is illustrated by pursuing the per-
fect linear relationship between the signal (M foot force) and the
magnitudes of transformation (measured by brake torque) with a
high degree of robustness.
In summary, the “robustness at different magnitudes of transforma-
tion” and the “robustness at controllability” are the real focuses of
Example 15.1.
Let’s examine a few more examples of ideal functions.

Example 15.2 Example of Ideal Functions
1. Semiconductor oxidation process
a. Main function. To oxidize a thin layer of material
b. Main transformation. Material transformation (changing material
with a chemical reaction)
c. Ideal function