A rule base modification scheme in fuzzy controllers for time-delay systems

In time-delay control systems, the observed information is naturally related to a past instant and this delayed information signal will usually cause unsatisfactory results. This study deals with how the time-delay information can be used in reorganizing the rule base of the fuzzy controller so as to improve system performance. It basically proposes a new scheme of appropriate shifting of the rule base to compensate the information lag caused by time delay in the system. The parameters affecting the shifting scheme are elaborated in detail and the new shifting scheme is proposed in a tabulated form that assumes the system time constant and the value of time delay as the main parameters. The effectiveness of the proposed methodology has firstly been tried to be illustrated on different simulation examples and, secondly, a real time application has been done on a heat transfer experimental setup. (C) 2008 Elsevier Ltd. All rights reserved.