Document Type : Research Articles
Authors
Faculty of Engineering, Mahallat Institute of Higher Education, Mahallat, Iran
Abstract
Advanced control of bioreactor systems is essential for enhancing efficiency and reliability in industrial bioprocesses. This paper introduces an adaptive robust dynamic surface control (DSC) approach for continuous stirred bioreactors, characterized by nonlinear microbial growth and significant model uncertainties. Unlike conventional bioreactor control formulations that treat the dilution rate as an instantaneously available input, the proposed framework considers the complete bioreactor–actuator cascade and explicitly incorporates the actuator dynamics into both controller synthesis and closed-loop stability analysis. Its distinguishing feature is the introduction of a second dynamic surface on the armature current, which couples the electrical actuator subsystem with the nonlinear bioreactor dynamics while avoiding repeated analytical differentiation of virtual control laws. The proposed DSC framework effectively addresses both parametric and non-parametric uncertainties through adaptive estimation and robust control laws. Lyapunov-based stability analysis proves that all tracking errors are uniformly ultimately bounded (UUB) within a compact set. MATLAB-based numerical simulations confirm that the substrate concentration tracks the desired trajectory with a settling time of 2.2 hours and an Integral of Absolute Error (IAE) of 9.07 (g/L).h. Moreover, the computational time per control step is only 0.0089 ms, indicating low algorithmic computational demand. Furthermore, the adaptive mechanism ensures that the adaptive estimates remain stable throughout operation, confirming the robustness and computational feasibility of the proposed framework. Experimental validation remains necessary before industrial implementation.
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