ABSTRACT
Control is the practice of influencing the static or dynamic behavior of a process—technical, biological, social or otherwise—with respect to a desired outcome. This chapter provides the basic terminology and concepts of control, and highlights the potential and limits of the various control concepts and methodologies. All control systems are built up from the interplay of four components: process dynamics, manipulated variables, measured variables, and controlled variables. Process models are at the heart of any control design approach and formalize the operator expectations in the process response to internal and external excitations. State controllability is a property of systems or processes that allows for achieving any combination of values of state variables by the available process inputs, either directly or indirectly through interaction of process states. In terms of drying processes, these could be arbitrary precise product moisture content, arbitrary composition and content of valuable ingredients, any customer-specified product temperature, and so on.
