ZD METHOD BASED NONLINEAR AND ROBUST CONTROL OF AGITATOR TANK

To improve industrial efficiency, an agitator tank system should have not only a short response time, but also produce reagents with accurate concentration and moderate liquid level. This paper presents a new method called Zhang dynamics (ZD) to perform tracking control, that is, to make the concentration and liquid level of the agitator tank converge to the desired trajectories. Two controllers for tracking control of an agitator tank system are designed based on ZD method. In addition, the robustness of the agitator tank system equipped with ZD controllers is investigated. Theoretical analyses on the convergence performance and robustness of the agitator tank system equipped with ZD controllers are presented. To substantiate the effectiveness of the ZD method for tracking control of the agitator tank system, we perform simulations on three different groups of tracking trajectories, which reflects the corresponding application conditions in the chemical industry. To test the robustness of the agitator tank system equipped with ZD controllers, additional simulations with different disturbances added in the agitator tank system and the ZD controllers are performed. Simulation results validate the feasibility and effectiveness of the ZD method for tracking control of the agitator tank system.