Closed Loop Reference Optimization for Extrusion Additive Manufacturing

TL;DR

This paper introduces a closed-loop control method using LQR with force feedback and preemptive reference optimization to improve filament width accuracy and response time in extrusion additive manufacturing.

Contribution

It presents a novel combination of LQR control with preemptive reference force optimization for enhanced extrusion process accuracy.

Findings

39.57% reduction in RMS error

83.7% shorter settling time

improved filament width tracking performance

Abstract

Various defects occur during material extrusion additive manufacturing processes that degrade the quality of the 3D printed parts and lead to significant material waste. This motivates feedback control of the extrusion process to mitigate defects and prevent print failure. We propose a linear quadratic regulator (LQR) for closed-loop control with force feedback to provide accurate width tracking of the extruded filament. Furthermore, we propose preemptive optimization of the reference force given to the LQR that accounts for the performance of the LQR and generates the optimal reference for the closed loop extrusion dynamics and machine constraints. Simulation results demonstrate the improved tracking performance and response time. Experiments on a Fused Filament Fabrication 3D printer showcase a root mean square error improvement of 39.57% compared to tracking the unmodified reference as well as an 83.7% shorter settling time.