Design of a self-tuning fuzzy logic controller for system with variable time delay

One of major obstacle to compensate varying time delay on dynamic system is that there is not an adequate method to handle the system time delay variation. Most of the existing time delay compensators required prior knowledge about the plants dynamics such as their order and time delay, which maybe not be available. In this research, a performance based fuzzy gain tuner is designed to compensate for variable time delay. This adaptation mechanism is added to PI and PID fuzzy controller. Two design and tuning methods are also developed for PIDFC. The advantages of the proposed adaptive method are that it doesn't requires any prior knowledge about the plants that will be controlled. These proposed design and adaptive methods have been applied to processes with variable gain and time delay to examined their robustness.; A stability analysis is also provided for all the proposed fuzzy logic controllers. This analysis uses the Popov method to determine the stability condition on the nonlinearity of FLCs. So that the closed-loop system is globally stable.