The paper presents the theory of performance sensitivity: distribution and
a novel robust parameter design technique. In the theory a Jacobian matrix
describes the effect of the component tolerance to the system performance,
and the performance distribution is characterized in the variation space by
a set of eigenvalues and eigenvectors. Thus, the feasible performance spac
e is depicted as an ellipsoid. The size, shape, and orientation of the elli
psoid describe the quantity las well as quality of the feasible space and t
herefore, the performance sensitivity distribution against the tolerance va
riation. The robustness of a design is evaluated by comparing the fitness b
etween the ellipsoid feasible space and the tolerance space, which is a blo
ck, through a set of quantitative and qualitative indexes. The robust desig
n can then be determined. The design approach is demonstrated in a mechanis
m design problem. Because of the generality of the analysis theory the meth
od call be used in any design situation as long as the relationship between
the performance and design variables can be expressed analytically.