ONLINE PERFORMANCE MONITORING OF 2-INPUTS-2-OUTPUTS MULTILOOP CONTROL-SYSTEMS

A monitoring procedure is proposed to on-line identify the maximum clo sed-loop log modulus, L(c,max), for two-inputs-two-outputs multiloop c ontrol system. L(c,max) is considered because it measures the robustne ss of control systems and thereby can indicate the appropriateness of controller design with respect to the current process condition. The p roposed method identifies L(c,max) via relay feedback experiments with out requiring an apriori information of process conditions. This proce dure is applied to both linear system and nonlinear system. The result s show that the proposed method is efficient and accurate in on-line i dentification of L(c,max).