Control structure selection and plantwide control

Consider the generalized control design problem in Figure 1. Here, the objective is to design the controller K, which, based on the measurements y, computes the inputs (MVs) u such that the controlled outputs (CVs) z are kept close to their desired setpoints, in spite of unknown disturbances, varying setpoints and measurement noise(w). However, note that it assumed that we know what to measure (y), manipulate (u), and, most importantly, what variables we would like to control (z), that is, we assume a given control structure. The term ”constrol structure selection” (CSS) and its synonym ”control structure deign” (CSD) is associated with the overall control philosophy for the system with emphasis on the structural decisions: