Section: New Results

Applications to wine fermentation

Participants : Térence Bayen, Céline Casenave, Jérôme Harmand, Alain Rapaport.

We study the problem of the control of a Multi-State Continuous Fermentor (MSCF) composed of 4 reactors connected in series (the experimental pilot plant is located at Montpellier, in the UMR SPO (INRA, Montpellier SupAgro, Univ. Montpellier 1)). The goal is to control the sugar concentration of the four reactors with, as control inputs, the input flow rates of the four reactors. The originality of the problem comes from the cascade structure of the device which leads to a constraint on the control inputs. Two control strategies have been studied.

An output stabilizing control strategy. The linearizing control law proposed in [66] , [67] (see Section 6.3.4 ) has been validated on numerical simulations, and then has been implemented (Labview-Matlab interface) on the experimental process. The obtained results are convincing; others experiments are scheduled in 2014 to refine the control law.

A minimal time state feedback strategy. The optimal state feedback studied in [62] (see Section 6.3.5 ) is of completely different nature, as it relies on bang-bang controls and singular arcs. We plan to couple this control law when far from the target with the previous stabilizing law when close from the target, in order to provide a practical sub-optimal strategy.

The first part of this work was conducted as a part of the European CAFE project (Computer-Aided Food processes for control Engineering) described in Section 8.3.1 , in collaboration with CESAME (Univ. Catholique de Louvain-la-neuve), and UMR SPO.

A new project, see Section 8.2 , in which the UMR SPO and the Unit Mistea are involved has begun in 2013. Preliminary work has been performed during the MSc thesis of S. Sekkat [74] about the modeling of the fermentation with addition of nitrogen in the MSCF.