Trajectory tracking control for the fermentation of biotechnological processes

Due to the increasing demand for dairy products during the last decade, the need for startercultures is growing rapidly. In order to fullfill the high requirements in both product output and quality, modern process control tools have to be applied to achieve an optimal fermentation. This paper presents a method to keep the concentration of the substrate lactose on a desired trajectory during the whole production process. Therefore we propose the application of a pre-control, where the optimal values of the actuating variable, in our case the feed of substrate, can be determined a priori using a simple process modell. The combination of the calculated feedforward-control and the well-known LQ-controller delivers very good agreement between desired trajectory and measured output and is therefore a suitable tool for the process control of starterculture fermentations.