Control of Fermentation Process by An On-Line Adaptive Technique

Abstract Control of a fermentation process is a complex problem due to inherent nonlinearities and time varying characteristics of the process. The application of conventional analogue controllers provides poor control due to problems in tuning individual loops. The application of standard optimal tecniques is complicated both by the complexity of the process and the lack of adequate models as a result of poorly understood dynamics. The problem is further complicated by the lack of important transducers for product measurement. Hence, the process provides a natural test for adaptive control techniques. The paper includes details of the multivariable parameter estimation, by recursive least squares as part of an adaptive control technique. A description of the operation of the adaptive controller is given in relation to its real-time application to a fermentation plant. Details of the pilot-plant, instrumentation and computer system are described highlighting the practical problems in these areas and the means hy which these problems have been overcome. Results are presented to show the successful performance of the adaptivetechnique on the pilot-plant. The work indicates that the application of the adaptive technique could provide great opportunities for enhancement of conventional control of fermentation processes.