Model-based Predictive and Backstepping controllers for a state coupled four-tank system with bounded control inputs: A comparative study

This paper investigates the problem of global tracking control design for a state coupled four-tank liquid level system with bounded control inputs. For this MIMO system׳s dynamics, motivated by a desire to provide precise liquid level control, two radically different control approaches are presented and compared: the nonlinear generalized predictive control (NGPC) and the Backstepping control. First, an analytical solution of the NGPC is developed based on the nominal model. Then, a nonlinear Backstepping controller is designed in order to ensure globally asymptotical stabilization for this nonlinear system. To ensure a suitable basis for their comparison, the two different control methods are designed and verified with the same test setup under the control input saturation imposed by the system's actuators. To highlight the efficiency and applicability of the proposed control schemes, simulation as well as experimental results are provided and discussed.