Tracking Control of Linear Systems

Chapter 1 Introduction

1.1 Time, physical variables and systems

Time is not only the basic constituent of the existence, but it is also the crucial physical variable for every process, every motion, for the work of every dynamic system, hence for every control system. The behavior of every plant, of its controller and of its control system occurs in time. The physical reality, the human experience with it, the human understanding, the accumulated human knowledge lead to the following definition of time [170], [171]:

Definition 2 [148] Time

Time (i.e., the temporal variable) t (or τ):

• – is an independent scalar physical variable,
• – its value called instant or moment determines uniquely when somebody or something started/ceased to exist,
• –  ...