SKEDSOFT

Determination of static position error constants

Fig: 1 Unity-feedback control system

Consider the unity feedback control system shown in Figure 1. Assume that the open-loop transfer function is given by

Fig: 2 Log-magnitude curve of a type 0 system

Figure 2 shows an example of the log-magnitude plot of a type 0 system. In such a system, the magnitude of G(jω) equals K_p at low frequencies, or

It follows that the low-frequency asymptote is a horizontal line at 20 log K_p dB.