ICS T9431 Input signals and transfer functions for the system

Mathematical techniques for analyzing and designing control systems fall into two categories:

Frequency range – In this type the state variables, the mathematical variables representing the input, output, and feedback of the system are expressed as function frequencies of the following items. The input signal and the transfer function of the system are converted from a function of time to a function of frequency such as the Fourier transform, the Laplace transform, or the z transform. The advantage of this technique is that it leads to mathematical simplification; The differential equation representing the code of the system is replaced by an algebraic equation that is much easier to solve in the frequency domain. However, as noted above, frequency-domain techniques can only be used with linear systems.

Time domain state space representation – In this type state variables are functions of time. In this model, the system being analyzed consists of one or more differential equations. Because frequency domain techniques are limited to linear systems, time domain is widely used to analyze nonlinear systems in the real world. Although these problems are more difficult to solve, modern computer simulation techniques such as analog languages make their analysis routine.