Fixed Time Performance Self-Recovery Control for Dissolved Oxygen Concentration Based on Failure Effect Observation

Dissolved oxygen concentration is a crucial part of the whole activated sludge wastewater treatment process (WWTP) because aerobic environment is beneficial to the growth of multiple microbes, but its involved nonlinear fashions bring obstacles to its precise regulation. In this paper, a failure effect observation-based fixed time performance self-recovery control (FEO-based FPSrC) strategy is developed for achieving dissolved oxygen regulation. Therein, aiming at the actuator failures, an indirect failure observation scheme is proposed to reconstruct the total failure effect, and promote the active compensation control. Meanwhile, the issue on unknown control gain function is solved by estimating the bound of such function online. Then, both the fixed time convergence and the tracking performance can be guaranteed using the fixed time stability criterion. Simulation validations are implemented on a WWTP platform, and the results on dissolved oxygen regulation indicate that the proposed control strategy can reduce the failure impact and ensure both the excellent control accuracy and fixed time stabilization.