In this paper, a fuzzy controller is designed based on parallel distributed compensation (PDC) method and it is implemented in an experimental tank level control system. Firstly, a mathematical model of the system is obtained experimentally. An important feature of the plant is its nonlinearity. To control the level of water in the tank over the whole range, the nonlinear model of the system is linearized around three different operating points. Then, three PI controllers are designed for the operating points, using Skogestad's method. By using the PDC method, an overall fuzzy controller is designed by the fuzzy blending of the three PI-controllers. To evaluate the practical performance of the PDC-based fuzzy controller, the control system is implemented in the experimental system. The evaluation criteria considered are step response and disturbance rejection. The comparison results showed the superiority of the PDC-controller over the classical PI-controller. 
Parallel distributed compensator design of tank level control based on fuzzy Takagi–Sugeno model