Online Learning-Based Predictive Control of Crystallization Processes
under Batch-to-Batch Parametric Drift
Abstract
This work considers a seeded fesoterodine fumarate (FF) cooling
crystallization and presents the methodology and implementation of a
real-time machine learning modeling-based predictive controller to
handle batch-to-batch (B2B) parametric drift. Specifically, an
autoencoder recurrent neural network-based model predictive controller
(AERNN-MPC) is developed to optimize product yield, crystal size, and
energy consumption while accounting for the physical constraints on
cooling jacket temperature. Deviations in the kinetic parameters are
considered in the closed-loop simulations to account for the B2B
parametric drift, and two error-triggered online update mechanisms are
proposed to address issues pertaining to the availability of real-time
crystal property measurements and are incorporated into the AERNN-MPC to
improve the model prediction accuracy. Closed-loop simulation results
demonstrate that the proposed AERNN-MPC with online update, irrespective
of the accessibility to real-time crystal property data, achieves a
desired closed-loop performance in terms of maximizing product yield and
minimizing energy consumption.