Journal of Zhejiang University SCIENCE
(ISSN 1009-3095, Monthly)

2005   Vol. 6B   No. 6   p.530-534

On-line estimation of concentration parameters in fermentation processes

XIONG Zhi-hua^†, HUANG Guo-hong, SHAO Hui-he

(Institute of Automation, Shanghai Jiaotong University, Shanghai 200030, China)
^†E-mail: zhxiong@sjtu.edu.cn
Received June 7, 2004; revision accepted Sept. 6, 2004

Abstract: It has long been thought that bioprocess, with their inherent measurement difficulties and complex dynamics, posed almost insurmountable problems to engineers. A novel software sensor is proposed to make more effective use of those measurements that are already available, which enable improvement in fermentation process control. The proposed method is based on mixtures of Gaussian processes (GP) with expectation maximization (EM) algorithm employed for parameter estimation of mixture of models. The mixture model can alleviate computational complexity of GP and also accord with changes of operating condition in fermentation processes, i.e., it would certainly be able to examine what types of process-knowledge would be most relevant for local models’ specific operating points of the process and then combine them into a global one. Demonstrated by on-line estimate of yeast concentration in fermentation industry as an example, it is shown that soft sensor based state estimation is a powerful technique for both enhancing automatic control performance of biological systems and implementing on-line monitoring and optimization.

Key words: Gaussian processes (GP), Expectation maximization (EM), Multiple models, Soft sensor, Yeast concentration, Fermentation processes
doi:10.1631/jzus.2005.B0530             CLC number: Q815