Manipal Journal of Science and Technology


Consider a coupled tank system at its level to be controlled which is an example of an uncertain system and it is also a Multiple-Input Multiple-Output (MIMO) system. This paper is to investigate the performance of the I-PD controller used to control the level of the coupled tank system. The variable to be controlled is the liquid level in tank2 and the manipulated variable is an inflow of tank1. Therefore, any control algorithm developed for the process should consider the interaction between loops. A control mechanism is required which provides a good deal between interaction and performance even in the presence of uncertainty due to model mismatches or environmental conditions specifically, when moderate interaction exists among the process variables. The characteristics of an I-PD controller compared with a PID controller designed based on the Small-gain theorem that will guarantee the closed-loop stability. The performance of the controllers is evaluated using various parameters such as ISE, settling time and percentage overshoot and simulation is carried out with the help of MATLAB - Simulink environment.