Control algorithms for a two tank liquid level system: An experimental study

The liquid level control in the coupled tank system (CTS) is a classical benchmark control problem. The dynamics of CTS resembles with that of many real systems such as distillation column, boiler process, oil refineries in petrochemical industries and many more. It is a most challenging benchmark control problem owing to its non linear and non-minimum phase characteristics. Furthermore, its physical constraints are also pose complexity in its control design. The thesis provides the description of a CTS along with its hardware setup used for carrying out research work. Usually, system identification is a procedure to obtain the mathematical model of a physical system from the experimental input-output data of the system. The entire process of identifying a system from input and output data broadly consists of six steps. It begins with an experimental design followed by data collection and data preprocessing, next a suitable model structure is selected, then the parameters of the model are estimated and finally the model is validated using the experimental data. The present work is aimed at utilizing the existing as well as developing new tools of system identification for obtaining a suitable model for the studied coupled tank apparatus. Based on the identified model, control algorithms are developed in order to maintain constant liquid levels in the presence of disturbances which is arising due to sudden opening of the valve in the tanks. A lot of research works have been directed in the past several years to develop the control strategies for a CTS. But, few works have been reported for validating the developed control strategies through the experimental setup. Thus, there lies a good opportunity to develop some advanced controllers and to implement them in real-time on the experimental set-up of a CTS in the laboratory.