  Liquid level control is very important in industrial field, where the liquid
level is required, and to prevent overflows. The coupled-tank is a common
system in industrial control processes. The system consists of two tanks
connected together and the liquid flows between them. Tanks contain an inlet
and outlet for each tank. The main principle of controlling this system is to
maintain a constant level of liquid in both tanks when there are an inflow and
outflow of liquid in each tank. To control liquid level in the coupled tank
system, the mathematical model of the system had been derived and evaluated as
a form of linear model. The mathematical model of coupled tank was developed to
apply to both conventional and fuzzy control systems where the dynamic behavior
of the system was considered. When the system had been designed the
corresponding model was implemented in simulation by using Matlab and Simulink
tools.
