Modelling and L<inf>1</inf> adaptive control of pH in bioethanol enzymatic process

Abstract

The enzymatic process is a key step in second generation bioethanol production. Pretreated biomass fibers are liquefied with the help of enzymes to facilitate fermentation. Enzymes are very sensitive to pH and temperature and the main control challenge in the nonlinear process is to ensure minimum deviations from the optimal pH level.This article develops a mathematical model for the pH, which has not been reported earlier for this particular process. The new model embeds flow dynamics and pH calculations and serves both for simulation and control design. Two control strategies are then formulated for pH level regulation: one is a classical PI controller; the other an L1 adaptive output feedback controller. Model-based feed-forward terms are added to the controllers to enhance their performances. A new tuning method of the L1 adaptive controller is also proposed. Further, a new performance function is formulated and tailored to this type of processes and is used to monitor the performances of the process in closed loop. The L1 design is found to outperform the PI controller in all tests.

Dynamic modeling and validation of a biomass hydrothermal pretreatment process—a demonstration scale study

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Modelling and &#x2112;<inf>1</inf> adaptive control of temperature in biomass pretreatment

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L1adaptive pitch control of an autonomous underwater vehicle

“…Since the L 1 -norm is equivalent to an L induced-norm of system input-output signal, it is gained for the stability and the performance assessment of the controller. Several implementations of this controller in various systems such different aircrafts (Hovakimyan and Cao, 2010;Hovakimyan et al, 2011;Capello et al, 2013), missile guidance and control (Erdos et al, 2012), remotely operated vehicles (Maalouf et al, 2013a, b), satellite control (Lee and Singh, 2012b), piezoelectricity actuator (Lee and Singh, 2012a) and control of PH at industrial processes (Prunescu et al, 2013) are successfully reported. Major application of L 1 adaptive controller similar to other adaptive controllers, is in the autonomous vehicles.…”