Screening criteria for input and output selection

The selection of inputs and outputs for control design are considered in this paper. Previous work by Cao and Biss [1] introduced the input effectiveness (IE) measure as a pre-screening tool for selecting inputs. An alternative and more efficient proof of these results is presented here using the concept of projection. This new approach for the derivation also helps when extending these ideas to output selection. The relationships between IE and the output effectiveness (OE) measures and the minimum singular value of a particular process configuration are determined. These yield four new screening criteria that can be used to indicate the scheme with the largest minimum singular value of all alternative schemes of the same dimension. Three examples are given to illustrate the usage of these criteria.