RELAY-BASED ONLINE MONITORING PROCEDURES FOR 2X2 AND 3X3 MULTILOOP CONTROL-SYSTEMS

A monitoring procedure is proposed to identify on-line the maximum clo sed-loop log modulus, L-c/max, for multiloop control systems. L-c,L-ma x is considered because it measures the robustness of the control syst ems and thereby can indicate the appropriateness of controller design with respect to the current operating conditions. The proposed method identifies L-c,L-max via relay feedback experiments without requiring a priori information of process conditions. This procedure is applied to both linear systems and nonlinear systems. The results show that th e proposed method is efficient and accurate in on-line identification of L-c/max.