A Digital Twin of Evaporative Thermo-Fluidic Process in Fixation Unit of DoD Inkjet Printers

TL;DR

This paper develops a modular digital twin for the evaporative thermo-fluidic process in inkjet printer fixation units, enabling real-time monitoring and robust state estimation using a novel PIE-based framework.

Contribution

It introduces a graph-theoretic, infinite-dimensional state estimator for the fixation process, integrating nonlinear evaporation modeling with stability and simulation analysis.

Findings

Validated with operational printer data

Achieved real-time thermal state estimation

Demonstrated robustness to disturbances

Abstract

In inkjet printing, optimal paper moisture is crucial for print quality, achieved through hot-air impingement in the fixation unit. This paper presents a modular digital twin of the fixation unit, modeling the thermo-fluidic drying process and monitoring its spatio-temporal performance. The novel approach formulates the digital twin as an infinite-dimensional state estimator that infers fixation states from limited sensor data, while remaining robust to disturbances. Modularity is achieved through a graph-theoretic model, where each node represents thermo-fluidic dynamics in different sections of the fixation unit. Evaporation is modeled as a nonlinear boundary effect coupled with node dynamics via Linear Fractional Representation. Using the Partial Integral Equation (PIE) framework, we develop a unified approach for stability, input-output analysis, simulation, and rapid prototyping, validated with operational data from a commercial printer. An $\mathcal{H}_{\infty}$-optimal Luenberger state estimator is then synthesized to estimate thermal states from available sensor data, enabling real-time monitoring of spatio-temporal thermal effects on paper sheets.