Evaluation of Closed-Loop Poles of Feedback Control Systems

Abstract

Of all the closed-loop poles of feedback control systems, the three or sometimes two closed-loop poles in the neighbourhood of the cross-over frequency ω_c at which the open-loop transfer function, G(s) reduces to unity in magnitude plays the decisive role in shaping the major form of the transient response of the system. However, the evaluation of the closed-loop real poles of higher-order feedback systems in the vicinity of the cross-over frequency ω_c (without use of a digital computer) is highly time-consuming and tedious. This paper presents a procedure entitled “Iterative deviation averaging method” for the rapid evaluation of the real-closed loop poles in the neighbourhood of ω_c, The procedure is illustrated with a simple example.

Indexing Terms:

• Feedback Control Systems
• Evaluation of Closed-Loop Poles of Control Systems