General Type-2 Fuzzy Logic Systems Using Shadowed Sets: A New Paradigm Towards Fault-Tolerant Control

Abstract

Fuzzy Inference Systems (FIS) are now widely employed to regulate a wide range of safety-critical engineering systems. The main reason for this is that FIS may be created using expert human knowledge. Furthermore, with the introduction of Type-2 Fuzzy Logic, the ability to handle uncertainty offers an alluring improvement for fault-tolerant abilities in fault-tolerant control methods, and, in fact, recent studies have shown that the use of Interval Type-2 Fuzzy Inference Systems (IT2 FIS) provides better results than Type-1 Fuzzy Inference Systems (T1 FIS).The current research intends to suggest a novel strategy employing Shadowed Type-2 Fuzzy Inference System (ST2 FIS) for significant features in fault-tolerant capability in the Passive Fault-Tolerant Control (PFTC) method based on the performance increase shown by IT2 FIS. The ST2 FIS is based on the ideas of Shadowed Fuzzy Sets and is an approximation of General Type-2 Fuzzy Inference Systems (GT2 FIS). The fundamental rationale for utilising ST2 FIS instead of GT2 FIS is that the computational cost of GT2 FIS is too high for this application. The simulation results for the FTC using IT2 FIS and FTC using ST2 FIS for Coupled Conical Tank Level Control (CCTLC) system with 30 % and 40% loss of effectiveness in the main actuator are presented in this study. In addition, the article compares the proposed FTC approach using ST2 FIS to FTC using IT2 FIS in terms of fault-recovery time.