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Resistance based iterative learning control of additive manufacturing with wire

P. Hagqvist ; A. Heralić ; A.K. Christiansson ; Bengt Lennartson (Institutionen för signaler och system, Automation)
Mechatronics (0957-4158). Vol. 31 (2014), p. 116-123.
[Artikel, refereegranskad vetenskaplig]

This paper presents successful feed forward control of additive manufacturing of fully dense metallic components. The study is a refinement of former control solutions of the process, providing more robust and industrially acceptable measurement techniques. The system uses a solid state laser that melts metal wire, which in turn is deposited and solidified to build the desired solid feature on a substrate. The process is inherently subjected to disturbances that might hinder consecutive layers to be deposited appropriately. The control action is a modified wire feed rate depending on the surface of the deposited former layer, in this case measured as a resistance. The resistance of the wire stick-out and the weld pool has shown to give an accurate measure of the process stability, and a solution is proposed on how to measure it. By controlling the wire feed rate based on the resistance measure, the next layer surface can be made more even. A second order iterative learning control algorithm is used for determining the wire feed rate, and the solution is implemented and validated in an industrial setting for building a single bead wall in titanium alloy. A comparison is made between a controlled and an uncontrolled situation when a relevant disturbance is introduced throughout all layers. The controller proves to successfully mitigate these disturbances and maintain stable deposition while the uncontrolled deposition fails.

Nyckelord: Additive manufacturing , Automatic control , Iterative learning control , Metal deposition , Process measurement , Resistance



Denna post skapades 2016-05-09.
CPL Pubid: 236108

 

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Institutioner (Chalmers)

Institutionen för signaler och system, Automation

Ämnesområden

Reglerteknik

Chalmers infrastruktur