On fuzzy observer for systems with both continuous and discrete measurements

This paper proposes the design of a fuzzy observer which uses both discrete and continuous measurements and updates the initial condition of the state of the system at each sampling instant to ensure the convergence of the estimation error. The proposed fuzzy observer is tested to estimate the substrate and biomass concentration of an anaerobic wastewater treatment process. The observer performance is compared via numerical simulation with two fuzzy observers which use only continuous measurements, showing a faster convergence rate. Finally, the whole estimation scheme is validated using experimental data from an anaerobic digestion process.