A Quantitative Controllability Index

A controllability index, which quantifies the cost associated with dynamic controllability, is proposed. The index depends quantitatively on the process alternative and control system alternative for each process alternative, and for each of these, the process dynamics, process constraints, product variability, disturbance characteristics, and controller/control structures. Its properties are discussed and its dependence on each of these factors is illustrated for the simplest possible case of a single unit (i.e., a distillation column).