Application of a robust interval observer to an anaerobic digestion process
Résumé
A new robust state estimation scheme is proposed for chemical and biochemical processes. This scheme is a nonlinear interval observer which is robust in the face of incertainties of the inputs, load disturbances and the nonlinearity of the system, while maintaining excellent stability conditions. We show that this observer yields satisfactory estimates of the unmeasured states whithin a guaranteed interval determined by the available measurements and some reasonable hypotheses about the observer inputs. For demonstrating the effectiveness and applicability of the proposed estimation scheme, we apply it in an actual anaerobic digestion pilot plant for wastewater treatment in the presence of uncertainties including measuring errors, sensor failures, time varying inputs and unmeasured disturbances. On-line implementation results reveal reveal that the proposed robust nonlinear interval observer is a practical and encouraging approach to the robust state estimation in uncertain nonlinear processes.