Gain Scheduled Adaptive PI Controller for a Hybrid Three Tank System

In this research work, a three tank process was taken for consideration in which two case studies has been discussed. In Case Study 1, two tanks are linked in cascade that allows them to communicate and the combination is connected in non interacting mode to the third tank. In case study 2, One tank is connected in non interacting fashion with the series connected tanks. This set up is practically applicable in all real time industries involving refineries; water treatment etc., hence controlling the plant with the disturbances being controlled is an enormous task. From the practical set up considered in the paper, the liquid level of the third tank is adjusted by varying the flow of liquid poured in the first tank that is treated as manipulated variable. Two control strategies are applied direct synthesis method and Gain scheduled Adaptive control. These are employed to monitor the performance parameters like settling point, Integral square error and Integral Absolute error. A new adaptive technique wherein the amplitude gains of Kp and Ki of the PI controller are adjusted so as to discard the consequence of disturbance at the load side or any adaptation in the set point and the planned system as per the desired closed loop trajectory.