MONITORING PROCEDURE FOR INTELLIGENT CONTROL - ONLINE IDENTIFICATION OF MAXIMUM CLOSED-LOOP LOG MODULUS

A monitoring procedure is proposed to decide whether a retuning of the controller is necessary. The well-known robustness measure, maximum closed-loop log modulus (L(c,max)), is used to indicate the appropriateness of the controller parameters. The monitoring procedure identifies the maximum closed-loop log modulus in two to three relay feedback experiments, a frequency domain approach. This procedure is tested against linear and nonlinear systems as well as systems with and without noise. The results show that the proposed method is very accurate in finding L(c,max) in an efficient manner.