2.4 Control Structure Design (The mathematically oriented
approach)
In this section we look at the mathematically oriented approach to plantwide control.
Structural methods
There are some methods that use structural information about the plant as a basis for control
structure design. For a recent review of these methods we refer to the coming monograph
of Ng and Stephanopoulos (1998a). Central concepts are structural state controllability, observability and accessibility. Based on this, sets of inputs and measurements are classified as viable or non-viable. Although the structural methods are interesting, they are not quantitative and usually provide little information other than confirming insights about the structure of the process that most engineers already have.
In the reminder of this section we discuss the five tasks of the control structure design
problem, listed in the introduction.
2.4.1 Selection of controlled outputs (c()
By “controlled outputs” we here refer to the controlled variables