A Loop-Shaping Method for Frequency-Based Design of Layer-To-Layer Control for Laser Metal Deposition

Author

Michelle L. Gegel
Douglas A. Bristow, Missouri University of Science and TechnologyFollow
Robert G. Landers, Missouri University of Science and TechnologyFollow

Abstract

Additive manufacturing processes fabricate parts in a layer-by-layer fashion, depositing material along a predefined path before incrementing to the next layer. Although the thickness of any given layer is bounded, in-layer dynamics can couple with layer-to-layer dynamics such that height defects amplify from one layer to the next. This is considered instability in the layer domain. By considering each layer as an iteration, additive processes can be categorized as repetitive processes. Although Repetitive Process Control (RPC) algorithms exist that can stabilize the process and converge to desired reference, it is typically assumed that the reference and disturbance are constant from layer to layer. In this paper, the problem of tracking references (layer thicknesses) that change from layer to layer is considered. The bandwidth of the changing references is considered bounded in both the spatial and layer domains. A loop-shaping design process is then considered, in which the bounds are mapped to a bound on the two-dimensional sensitivity function and projected onto weighting filters in an LQR control formulation. The layer-to-layer controller is then constructed from traditional LQR methods. The controller is demonstrated on a simulation of laser metal deposition for a wavy wall build having frequency content in both the spatial and layer domains.

Recommended Citation

M. L. Gegel et al., "A Loop-Shaping Method for Frequency-Based Design of Layer-To-Layer Control for Laser Metal Deposition," Proceedings of the American Control Conference, pp. 487 - 491, Institute of Electrical and Electronics Engineers (IEEE), Jul 2020.

The definitive version is available at https://doi.org/10.23919/ACC45564.2020.9147878

Meeting Name

American Control Conference, ACC 2020 (2020: Jul. 1-3 Denver, CO)

Department(s)

Mechanical and Aerospace Engineering

Comments

Missouri University of Science and Technology, Grant P200A180061

International Standard Book Number (ISBN)

978-153868266-1

International Standard Serial Number (ISSN)

0743-1619

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2020 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

03 Jul 2020