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Robotic Friction Stir Welding—Seam-Tracking Control, Force Control and Process Supervision

Karlsson, Martin LU ; Bagge Carlson, Fredrik LU ; Holmstrand, Martin ; Robertsson, Anders LU ; De Backer, Jeroen ; Quintino, Luisa ; Assunçao, Eurico and Johansson, Rolf LU orcid (2023) In Industrial Robot 50(5). p.722-730
Abstract
Purpose – This study aims to enable robotic friction stir welding (FSW) in practice. The use of robots has hitherto been limited, because of the large contact forces necessary for FSW. These forces are detrimental for the position accuracy of the robot. In this context, it is not sufficient to rely on the robot’s internal sensors for positioning. This paper describes and evaluates a new method for overcoming this issue.

Design/methodology/approach – A closed-loop robot control system for seam-tracking control and force control, running and recording data in real-time operation, was developed. The complete system was experimentally verified. External position measurements were obtained from a laser seam tracker and deviations from... (More)
Purpose – This study aims to enable robotic friction stir welding (FSW) in practice. The use of robots has hitherto been limited, because of the large contact forces necessary for FSW. These forces are detrimental for the position accuracy of the robot. In this context, it is not sufficient to rely on the robot’s internal sensors for positioning. This paper describes and evaluates a new method for overcoming this issue.

Design/methodology/approach – A closed-loop robot control system for seam-tracking control and force control, running and recording data in real-time operation, was developed. The complete system was experimentally verified. External position measurements were obtained from a laser seam tracker and deviations from the seam were compensated for, using feedback of the measurements to a position controller.

Findings – The proposed system was shown to be working well in overcoming position error. The system is flexible and reconfigurable for batch and short production runs. The welds were free of defects and had beneficial mechanical properties.
Research limitations/implications – In the experiments, the laser seam tracker was used both for control feedback and for performance evaluation. For evaluation, it would be better to use yet another external sensor for position measurements, providing ground truth.

Practical implications – These results imply that robotic FSW is practically realizable, with the accuracy requirements fulfilled.

Originality/value – The method proposed in this research yields very accurate seam tracking as compared to previous research. This accuracy, in turn, is crucial for the quality of the resulting material.

Keywords Friction stir welding, Robotics, Force control, Seam-tracking control, Control, Sensors, Robot welding (Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Friction stir welding, Robotics, Force control, Seam-tracking control, Control, Sensors, Robot welding
in
Industrial Robot
volume
50
issue
5
pages
9 pages
publisher
Emerald Group Publishing Limited
external identifiers
  • scopus:85147562890
ISSN
0143-991X
DOI
10.1108/IR-06-2022-0153
project
Flexifab
RobotLab LTH
language
English
LU publication?
yes
id
f68583ac-4172-47a4-bc57-fbfbe9f31adb
date added to LUP
2023-02-16 09:02:01
date last changed
2025-03-04 10:38:27
@article{f68583ac-4172-47a4-bc57-fbfbe9f31adb,
  abstract     = {{Purpose – This study aims to enable robotic friction stir welding (FSW) in practice. The use of robots has hitherto been limited, because of the large contact forces necessary for FSW. These forces are detrimental for the position accuracy of the robot. In this context, it is not sufficient to rely on the robot’s internal sensors for positioning. This paper describes and evaluates a new method for overcoming this issue.<br/><br/>Design/methodology/approach – A closed-loop robot control system for seam-tracking control and force control, running and recording data in real-time operation, was developed. The complete system was experimentally verified. External position measurements were obtained from a laser seam tracker and deviations from the seam were compensated for, using feedback of the measurements to a position controller.<br/><br/>Findings – The proposed system was shown to be working well in overcoming position error. The system is flexible and reconfigurable for batch and short production runs. The welds were free of defects and had beneficial mechanical properties.<br/>Research limitations/implications – In the experiments, the laser seam tracker was used both for control feedback and for performance evaluation. For evaluation, it would be better to use yet another external sensor for position measurements, providing ground truth.<br/><br/>Practical implications – These results imply that robotic FSW is practically realizable, with the accuracy requirements fulfilled.<br/><br/>Originality/value – The method proposed in this research yields very accurate seam tracking as compared to previous research. This accuracy, in turn, is crucial for the quality of the resulting material.<br/><br/>Keywords Friction stir welding, Robotics, Force control, Seam-tracking control, Control, Sensors, Robot welding}},
  author       = {{Karlsson, Martin and Bagge Carlson, Fredrik and Holmstrand, Martin and Robertsson, Anders and De Backer, Jeroen and Quintino, Luisa and Assunçao, Eurico and Johansson, Rolf}},
  issn         = {{0143-991X}},
  keywords     = {{Friction stir welding; Robotics; Force control; Seam-tracking control; Control; Sensors; Robot welding}},
  language     = {{eng}},
  month        = {{02}},
  number       = {{5}},
  pages        = {{722--730}},
  publisher    = {{Emerald Group Publishing Limited}},
  series       = {{Industrial Robot}},
  title        = {{Robotic Friction Stir Welding—Seam-Tracking Control, Force Control and Process Supervision}},
  url          = {{https://lup.lub.lu.se/search/files/138023718/karlsson2023robotic_fsw.pdf}},
  doi          = {{10.1108/IR-06-2022-0153}},
  volume       = {{50}},
  year         = {{2023}},
}