Robust Output Feedback Control Design for Nonlinear Coupled-tank System using Linear Matrix Inequalities

In this experimental study, the Robust Output Feedback controller (ROF) is designed based on the H_∞ theory and implemented to the level control of the coupled tank system. As many chemical processes have complicated and nonlinear characteristics, this robust methodology is proposed to tackle them. Hence, the vertical coupled tank system is selected as one of the popular case study systems to simulate the large-scale chemical processes to illustrate the effectiveness of the proposed ROF controller. Linear Matrix Inequalities (LMIs) methodology is selected as the main mathematical method of the design procedure. To illustrate the best performance and robustness of the ROF controller, the simulation and experimental results are compared to the Feedforward Proportional Integrator, one of the most common controllers in the industries. Two different liquid level control scenarios are considered in this comparison and the obtained results show the expected performance of the ROF controller guaranteeing the design objectives.