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Substrate Control of Biotechnical Fedbatch Processes. Robustness and the Role of Adaptivity

Axelsson, Jan Peter; Holst, Olle LU and Hagander, Per LU (1990) 11th IFAC World Congress
Abstract
Results from experiments on laboratory scale fedbatch processes are presented as well as analysis and design of the control system. The main reason for control is to track the drastic growth in feed demand during a cultivation. Variations in the amount and quality of the inocculum makes precalculated dosage schemes of limited value to obtain reproducible cultivation conditions. Two processes have been studied on a laboratory scale, production of bakers' yeast, and production of the enzyme salicylate hydroxylase using a strain of bacteria. Direct measurement was used to monitor the feed demand. A regulator structure is proposed based on an observer for the exponentially growing feed demand. It can be viewed as a modified PID regulator... (More)
Results from experiments on laboratory scale fedbatch processes are presented as well as analysis and design of the control system. The main reason for control is to track the drastic growth in feed demand during a cultivation. Variations in the amount and quality of the inocculum makes precalculated dosage schemes of limited value to obtain reproducible cultivation conditions. Two processes have been studied on a laboratory scale, production of bakers' yeast, and production of the enzyme salicylate hydroxylase using a strain of bacteria. Direct measurement was used to monitor the feed demand. A regulator structure is proposed based on an observer for the exponentially growing feed demand. It can be viewed as a modified PID regulator around a dosage scheme, but it is less sensitive to errors in the dosage scheme than conventional PID control. The a priori knowledge of the feed profile is further relaxed by introduction of adaptation of the growth rate parameter. The obtained non-linear control system has a simple structure and stability is garanteed for a wide range of initial values using the technique of Liapunov function. The linearized system is analysed in the frequency domain and the adaptation is shown to have negligible influence on the loop phase margin. The adaptive regulator is tested in simulation against real feed profiles and shows good results. (Less)
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organization
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Contribution to conference
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published
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keywords
Fedbatch process, PID-regulator, structured uncertainity, internal disturbance model, extended Kalman filter, robustness
conference name
11th IFAC World Congress
language
English
LU publication?
yes
id
dbf8c872-12ab-489b-adf3-edbec7c290a0 (old id 8517463)
date added to LUP
2016-01-19 11:04:45
date last changed
2016-04-16 12:18:57
@misc{dbf8c872-12ab-489b-adf3-edbec7c290a0,
  abstract     = {Results from experiments on laboratory scale fedbatch processes are presented as well as analysis and design of the control system. The main reason for control is to track the drastic growth in feed demand during a cultivation. Variations in the amount and quality of the inocculum makes precalculated dosage schemes of limited value to obtain reproducible cultivation conditions. Two processes have been studied on a laboratory scale, production of bakers' yeast, and production of the enzyme salicylate hydroxylase using a strain of bacteria. Direct measurement was used to monitor the feed demand. A regulator structure is proposed based on an observer for the exponentially growing feed demand. It can be viewed as a modified PID regulator around a dosage scheme, but it is less sensitive to errors in the dosage scheme than conventional PID control. The a priori knowledge of the feed profile is further relaxed by introduction of adaptation of the growth rate parameter. The obtained non-linear control system has a simple structure and stability is garanteed for a wide range of initial values using the technique of Liapunov function. The linearized system is analysed in the frequency domain and the adaptation is shown to have negligible influence on the loop phase margin. The adaptive regulator is tested in simulation against real feed profiles and shows good results.},
  author       = {Axelsson, Jan Peter and Holst, Olle and Hagander, Per},
  keyword      = {Fedbatch process,PID-regulator,structured uncertainity,internal disturbance model,extended Kalman filter,robustness},
  language     = {eng},
  title        = {Substrate Control of Biotechnical Fedbatch Processes. Robustness and the Role of Adaptivity},
  year         = {1990},
}