Robust Linear Quadratic Optimal Control of Cementitious Material Extrusion

TL;DR

This paper introduces a robust control framework combining sliding mode and linear quadratic optimal control to improve stability and accuracy in cementitious material extrusion 3D printing, addressing disturbances and uncertainties.

Contribution

It develops a hybrid control architecture for cementitious extrusion, integrating disturbance rejection with energy-efficient tracking, a novel approach for this application.

Findings

Guarantees convergence of flow tracking errors under disturbances

Ensures robustness and optimality in simulation scenarios

Addresses flow stability and dimensional fidelity challenges

Abstract

Extrusion-based 3D printing of cementitious materials enables fabrication of complex structures, however it is highly sensitive to disturbances, material property variations, and process uncertainties that decrease flow stability and dimensional fidelity. To address these challenges, this study proposes a robust linear quadratic optimal control framework for regulating material extrusion in cementitious direct ink writing systems. The printer is modeled using two coupled subsystems: an actuation system representing nozzle flow dynamics and a printing system describing the printed strand flow on the build plate. A hybrid control architecture combining sliding mode control for disturbance rejection with linear quadratic optimal feedback for energy-efficient tracking is developed to ensure robustness and optimality. In simulation case studies, the control architecture guarantees acceptable convergence of nozzle and strand flow tracking errors under bounded disturbances.