Implementation of fuzzy-PID controller to liquid level system using LabVIEW

Abstract

The paper describes about the liquid level control system which is commonly used in many process control applications. The output of the level process is non-linear and it is converted into the linear form by using Taylor Series method. The aim of the process is to keep the liquid level in the tank at the desired value. The conventional proportional-integral-derivative (PID) controller is simple, reliable and eliminates the steady state error. Fuzzy logic controllers are rule based systems which are logical model of the human behavior of the process. The fuzzy controller is combined with the PID controller and then applied to the tank level control system. This paper compares the transient response as well as error indices of PID, fuzzy, fuzzy- PID controllers. The responses of the fuzzy-PID controller are verified through simulation. From the simulation results, it is observed that fuzzy-PID controller gives the superior performance than the other controllers. The absolute error of fuzzy-PID controller is 56.6% less than PID controller and 55.6% less than the fuzzy controller. The LabVIEW software is used to simulate the system. The simulated results validate the method implemented here.