A Self-Organizing Sliding-Mode Controller for Wastewater Treatment Processes

Nonlinearity, uncertainties, and disturbances exist extensively in wastewater treatment processes (WWTPs), which result in control performance degradation and critical instability. To solve this problem, an efficient self-organizing sliding-mode controller (SOSMC) is proposed to achieve acceptable and stable control performance for WWTPs. The novelties of SOSMC involve: 1) a practical control strategy, combining advantages of sliding-mode control and fuzzy-neural network, was designed to suppress the disturbances and uncertainties of WWTPs; 2) a self-organizing mechanism, based on the tracking error and structure complexity, was developed to alleviate the chattering phenomenon of SOSMC and improve the control performance; and 3) the stability analysis, including the fixed and adaptive structures, was given to ensure the successful applications of SOSMC. Finally, experimental investigations on a real WWTP are employed to validate the merits of the proposed method.