BULETINUL INSTITUTULUI POLITEHNIC DIN IAŞI - Universitatea ...

Bul. Inst. Polit. Iaşi, t. LVI (LX), f. 2, 2010 3
the decoupled and the coupled conditions are impossible to attain in any singlerequirement
design because there is no different FRs to couple.
The present work contains an analysis of the pattern of the design matrix of
redundant designs with more than one requirement (m > 1), a matter to which
the researchers have not paid sufficient attention so far.
2. The Key Characteristics of Redundant Designs
Fig. 2 depicts the design of a simple clamping device with one only
customer need: the clamping action, which can be attained by adjusting one
only FR — the distance d.
Fig. 2 – Example of a simple redundant design.
The adjustment of d can be achieved by suitably setting the values of two
design parameters: the position of the cam in the end of the hand lever (see Fig.
1), which is denoted by angle α, and the angular position of the threaded rod,
which is represented by angle β. Thus, the design equation for this redundant
design with one requirement and two parameters is:
(2) d
⎡
⎣
{}= A 11 A 12
⎧
⎤
⎪ α ⎫⎪
⎦ ⎨ ⎬ .
β
⎩⎪ ⎭⎪
A more general case is the Eq. (3) that represents a design with arbitrary
numbers of requirements m and parameters n, with m < n. The equation relates
to a redundant design, and its quality depends on the pattern of the design
matrix, as per Theorem 3.
To better understand how the pattern of the design matrix of Eq. (3) could
characterize a good or a poor design, let us consider the three coexisting designs