[en] In this study, the application of Lipschitz observers to the monitoring of cultures
of micro-algae in photo-bioreactors is investigated. To design the observer, the dynamic model
has to be structured into an observable linear part and a nonlinear Lipschitz part. A systematic
method is proposed for the definition of the linear part, so as to ensure that it is stable and
observable. The observer is tested in a real-life application, namely cultures of micro-algae
Scenesdesmus obliquus, where the internal quota has to be estimated from either biomass
measurements only or biomass and medium substrate concentrations. The Lipschitz observer
shows robust performance, as compared to the extended Kalman filter.
