EKF vs. UKF: Important Aspects in the Observation of Bioprocesses

In this work, a comparison between the extended Kalman filter (EKF) and the unscented Kalman filter (UKF) was made to determine the states of a lactic acid fermentation process in a bioreactor that operates continuously. The model proposed by Lombardi in 1999 was used. To compare the filters, 2 strategies were established [1]. Measure biomass concentration and estimate substrate and lactic acid; and [2]. Measure the concentration of lactic acid to estimate biomass and substrate. Both proposals satisfy the observability and the simulations carried out show similar behaviors, even; on some ranges EKF performs better than UKF. This result had already been reported. Finally, strategy (1) yielded more precise observations than strategy (2). However, acquiring a biomass probe requires a high investment. For this reason, opting for a pH meter (strategy 2) does not sound unreasonable, especially since it offers substantial savings.