ABSTRACT
This chapter introduces the concept of control in an engineering context, and examines the wide variety of control tasks in a large engineering system. It describes the three common control strategies – open loop, feedforward, and feedback. Control engineering can perhaps be summed up as the design and implementation of automatic control systems to achieve specified objectives under given constraints. No control system can be designed without a clear specification of control objectives. For a complex system, the overall objectives and constraints will need to be translated into performance specifications for the various subsystems -ultimately into control system specifications for low-level subsystems. For a chemical plant as a whole, the ultimate control objective might be to produce a final product meeting quality specifications, while minimizing costs. Control engineering as a discipline is characterized by a common approach to a great variety of control tasks, and by a set of mathematical tools which have proved to be generally applicable.
