Introduction

Abstract

The main goal of control engineering is to ensure that some system of interest performs according to a given specification, often under conditions of uncertainty and with as little human intervention as possible. In general, the uncertainty arises because of insufficient knowledge about the system itself or the environment in which it operates. This could be due to a highly complex plant, components that change their characteristics because of failure or drift, and the presence of unpredictable external disturbances. The specification, which need not be constant so as to accommodate for possible changes in the control objectives, defines how the variables of interest within the system are required to behave. This goal demands the system to effect some form of self-regulation. Control theory shows that in general, the most reliable way of achieving this, is by connecting a suitably designed controller in a feedback configuration with the system.