1. Time domain analysis: the stabil

1. Time domain analysis: the stability, transient and steady-state performance of the control system are analyzed according to the expression of output in time domain under certain input.2. Frequency domain analysis: an engineering method to study control system. The signal in the control system can be expressed as a combination of sinusoidal signals with different frequencies. The mathematical model describing the relationship between the steady-state output and input signals of the control system under the action of sinusoidal functions of different frequencies is called frequency characteristic, which reflects the response performance of the system under the action of sinusoidal signals.1. Time domain analysis: when the initial value is zero, we usually use the transfer function to indirectly evaluate the performance of the system.2. Frequency domain analysis: a graphical method for studying linear systems using frequency characteristics, as shown in Figure 4-3. Like transfer functions, frequency characteristics can be used to represent the dynamic characteristics of linear systems or links. The frequency domain method based on the frequency characteristics of the analysis and control system makes up for the deficiency of the time domain method, so it has been widely used.