Level Control in Horizontal Tank by Fuzzy-PID Cascade Controller

The paper describes the Fuzzy–PID cascade controller to control the level of horizontal tank that has diameter 300 mm and 480 mm long. Interface card module PCI-6024E in computer and Lab View software program is used for built the cascade controller. Structure of its where the inner loop is a PID controller for regulating flow rate of system and outer loop is a Fuzzy logic controller for control the level. The response time, steady state error, load disturbance, and control valve action of cascade are tested and compared with the simple controller. The experimental shows that at the same water level 50% set-point, the rising time to set-point of cascade controller is less than the simple controller about 1750 ms, and it has steady state error less than simple controller about ±1% . The load disturbance on the plant has no affect when using the cascade controller. The control valve action of the cascade controller has operation high frequency than the simple controller so the water level in horizontal tank is smoothly constant. Overshoot affect on cascade and simple controller has not occurred. the cascade controller that consist of the PID and the fuzzy logic control to improve the dynamic characteristic of the level control in horizontal tank. The performance of it will comparing with the simple loop or fuzzy logic controller. Keywords—Fuzzy PID, level control, horizontal tank.