Stefan Ericson

Mr. Stefan Ericson

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Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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18 August 2025 in Sensors
Verified
Journal Article
Open access
PDF file
ADAmena Darwish
Amena Darwish
MPManfred Persson
Manfred Persson
SEStefan Ericson
Stefan Ericson
RGRohollah Ghasemi
Rohollah Ghasemi
KSKent Salomonsson
Kent Salomonsson
Laser beam welding (LBW) involves complex and rapid interactions between the laser and material, often resulting in defects such as pore formation. Emissions collected during the process offer valuable insight but are difficult to interpret directly for defect detection. In this study, we propose a data-driven framework to interpret electromagnetic emissions in LBW using both supervised and unsupervised learning. Our framework is implemented in the post-process monitoring stage and can be used as a real-time framework. The supervised approach uses labeled data corresponding to predefined defects (in this work, pore formation is an example of a defined defect). Meanwhile, the unsupervised method is used to identify anomalies without using predefined labels. Supervised and unsupervised learning aims to find reference values in the emissions data to determine the values of signals that lead to defects in welding (enabling quantitative monitoring). A total of 81 welding experiments were conducted, recording real-time emission data across 42 spectral channels. From these signals, statistical, temporal, and shape-based features were extracted, and dimensionality was reduced using Principal Component Analysis (PCA). The LSTM model achieved an average mean squared error (MSE) of 0.0029 and mean absolute error (MAE) of 0.0288 on the testing set across five folds. The Isolation Forest achieved 80% accuracy and 85.7% precision in detecting anomalous welds on a subset with validated defect labels. The proposed framework enhances the interpretability of 4D photonic data and enables both post-process analysis and potential real-time monitoring. It provides a scalable, data-driven approach to weld quality assessment for industrial applications.

30 October 2009
Verified
Book Chapter
Closed access
PDF file
SEStefan Ericson
Stefan Ericson
BÅB. Åstrand
B. Åstrand
CLClose
Close
In this paper we have developed a mobile robot which is able to perform crop-scale operations using vision as only sensor. The system consists of a row-following system and a visual odometry system. The row following system captures images from a front looking camera on the robot and the crop rows are extracted using Hough transform. Both distance to the rows and heading angle is provided which both are used to control the steering. The visual odometry system uses two cameras in a stereo setup pointing perpendicular to the ground. This system measures the travelled distance by measuring the ground movement and compensates for height variation. Experiments are performed on an artificial field due to the season. The result shows that the visual odometry has accuracy varying between 0.7% and 2.1% of travelled distance.

16 September 2024 in Journal of Laser Applications
Verified
Journal Article
Open access
PDF file
ADAmena Darwish
Amena Darwish
SEStefan Ericson
Stefan Ericson
RGRohollah Ghasemi
Rohollah Ghasemi
TATobias Andersson
Tobias Andersson
DLDan Lönn
Dan Lönn
KSKent Salomonsson
Kent Salomonsson
To advance quality assurance in the welding process, this study presents a deep learning (DL) model that enables the prediction of two critical welds’ key performance characteristics (KPCs): welding depth and average pore volume. In the proposed approach, a wide range of laser welding key input characteristics (KICs) is utilized, including welding beam geometries, welding feed rates, path repetitions for weld beam geometries, and bright light weld ratios for all paths, all of which were obtained from hairpin welding experiments. Two DL networks are employed with multiple hidden dense layers and linear activation functions to investigate the capabilities of deep neural networks in capturing the complex nonlinear relationships between the welding input and output variables (KPCs and KICs). Applying DL networks to the small numerical experimental hairpin welding dataset has shown promising results, achieving mean absolute error values of 0.1079 for predicting welding depth and 0.0641 for average pore volume. This, in turn, promises significant advantages in controlling welding outcomes, moving beyond the current trend of relying only on defect classification in weld monitoring to capture the correlation between the weld parameters and weld geometries.