Sliding mode disturbance observer-based the port-controlled Hamiltonian control for a four-tank liquid level system subject to external disturbances

In this paper, a new port-controlled Hamiltonian(PCH) method based on disturbance observer is proposed considering the presence of disturbance in a four-tank liquid level system. Firstly, the PCH model of the four-tank the liquid level system is established by using PCH principle. secondly, the basic feedback controller is designed by configuring the interconnection structure and damping injection. Thirdly, a nonlinear disturbance observer is designed to suppress the disturbance in the four-tank liquid level system. Finally, the simulation results show that the proposed control strategy has better steady-state performance and robustness than the terminal sliding mode control method.