A Type-2 PI Controller with Adjustable Type-Reduced Output

Type-2 fuzzy logic theory is a framework designed to better accommodate the uncertainties that is ubiquitous in real-world applications. This paper aims at handling uncertainties by introducing a type-2 fuzzy controller that is equivalent to a PI controller with bounded gains. The range of equivalent proportional and integral gains may be selected using empirical PI tuning algorithm such as the Ziegler-Nichols and the ITAE setpoint tuning method. In order to maintain consistent performances regardless of the actual value of the process parameters, an algorithm is proposed for adjusting the centroids of the consequent type-2 sets, and therefore the controller output. Simulation results are presented to demonstrate the feasibility of the proposed type-2 fuzzy PI controller