TY - GEN A1 - Rueda-Escobedo, Juan G. A1 - Sbarciog, Mihaela A1 - Moreno, Jaime A. A1 - Van Impe, Jan A1 - Wouwer, Alain Vande T1 - Robust State and Input Estimation with Enhanced Convergence Rate for Monitoring Anaerobic Digestion T2 - Journal of Process Control N2 - In this study, an observer for estimating the state and unknown inputs is proposed for monitoring anaerobic digestion processes. This estimator is based on a dynamic model considering acidogenesis and methanogenesis, and consists of three sub-observers: (a) a gramian-based fixed-time convergent observer for the inlet chemical oxygen demand (COD) and the acidogenic bacteria population, (b) an asymptotic observer for the methanogenic bacteria population, and (c) a super-twisting observer for systems with time-varying parameters to estimate the inlet volatile fatty acid (VFA) concentration. These sub-observers can be designed independently, which greatly simplifies the tuning process. Proofs of convergence are developed and simulation tests show the performance of the estimation scheme as compared to classical extended Kalman filtering. Y1 - 2022 UR - https://www.sciencedirect.com/science/article/pii/S0959152422001421 U6 - https://doi.org/10.1016/j.jprocont.2022.07.014 SN - 0959-1524 VL - 117 IS - 4 SP - 169 EP - 180 ER -