ABSTRACT
Aim of this chapter is to provide a few main results related to time-delay systems. The concepts explored in this chapter have a fundamental importance in robust control theory due to the implications of time-delay in practical implementations of control systems. Indeed, time-delay systems are accurate models of real systems. Control engineers tend to neglect the presence of time-delay in feedback loops assuming that the control input is presented in the proper time to observe the desired response. However, many systems are based on the existence of a time-delay, such as radars and sonars whose working principle relies on the time-delay between the emitted wave and the reception of the echo. Moreover, the presence of a human operator in a control loop is modeled as a time-delay, an aspect of crucial importance in the theory of human-machine interaction.
