| 1. |
- Adolfsson, Stefan, et al.
(author)
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A Sequential Probability Ratio Test Method for Quality Monitoring in Robotised GMA Welding
- 1997
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Conference paper (peer-reviewed)abstract
- This paper deals with the problem of automatic monitoring the weld quality when welding with Gas Metal Arc (GMA) in short circuiting mode. Experiments with two different types of T-joints are performed in order to provoke optimal and non-optimal welding conditions. During the experiments, voltage and current are measured from the welding process. A simple statistical change detection algorithm for the weld quality, the repeated Sequential Probability Ratio Test (SPRT), is used. The algorithm can equivalently be viewed as a cumulative sum (CUSUM) - type test. The test statistics is based upon the fluctuations of amplitude in the weld voltage. It is shown that the fluctuations of the weld voltage amplitude decreases when the welding process is not operating under optimal condition. The results obtained from the experiments indicate that it is possible to detect changes in the weld quality automatically and on-line.
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| 2. |
- Adolfsson, Stefan, et al.
(author)
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Automatic Detection of Burn-through in GMA Welding Using a Parametric Model
- 1996
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In: Mechanical Systems & Signal Processing. - London : Academic Press. - 0888-3270. ; 10:5, s. 633-651
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Journal article (peer-reviewed)abstract
- This paper addresses the problem of automatic detection of burn-through in weld joints. Gas metal are (GMA) welding with pulsed current is used, and welding voltage and current are recorded. As short-circuitings are common between the welding electrode and the work piece during burn-through, a short-circuit detector is developed to detect these events. To detect another specific characteristic of burn-through-a broadband long-lasting voltage component-this detector is combined with a square-law detector. This second detector is based on a non-linear modification of an autoregressive model with extra input (ARX-model) of the welding process. The results obtained from this compound detector indicate that it is possible to detect burn-through in the welds automatically. The work also indicates that it is possible to design an on-line monitoring system for robotic GMA welding.
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| 4. |
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| 5. |
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| 6. |
- Adolfsson, Stefan, et al.
(author)
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On-line quality monitoring in short : circuit gas metal arc welding
- 1999
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In: Welding Journal. - New York,N.Y. : American welding society. - 0043-2296. ; 78:2, s. 59S-73S
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Journal article (peer-reviewed)abstract
- This paper addresses the problems involved in the automatic monitoring of the weld quality produced by robotized short-arc welding. A simple statistical change detection algorithm for the weld quality, the repeated Sequential Probability Ratio Test (SPRT), was used. The algorithm may similarly be viewed as a cumulative sum (CUSUM) type test, and is well-suited to detecting sudden minor changes in the monitored test statistic. The test statistic is based on the variance of the weld voltage, wherein it will be shown that the variance decreases when the welding process is not operating under optimal conditions. The performance of the algorithm is assessed through the use of experimental data. The results obtained from the algorithm show that it is possible to detect changes in weld quality automatically and on-line.
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| 7. |
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| 8. |
- Adolfsson, Stefan, et al.
(author)
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Quality Monitoring in Robotised Welding using Sequential Probability Ratio test
- 1996
-
Conference paper (peer-reviewed)abstract
- This paper addresses the problem of automatic monitoring the weld quality produced by robotised short arc welding. A simple statistical change detection algorithm for the weld quality, recursive sequential probability ratio test (SPRT), is used. The algorithm may equivalently be viewed as a cumulative sum (CUSUM) type test. The test statistics is based upon the variance of the amplitude of the weld voltage. It is shown that the variance of the weld voltage amplitude decreases when the welding process is not operating under optimal condition. The performance of the algorithm is evaluated using experimental data. The results obtained from the algorithm indicate that it is possible to detect changes in the weld quality automatically and on-line
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| 9. |
- Adolfsson, Stefan
(author)
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Quility Monitoring in Robotised Short Circuiting GMA Welding
- 1997
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Reports (other academic/artistic)abstract
- This paper addresses the problem of automatic monitoring the weld quality produced by robotised short arc welding. A simple statistical change detection algorithm for the weld quality, recursive Sequential Probability Ratio Test (SPRT), is used. The algorithm may equivalently be viewed as a cumulative sum (CUSUM) - type test. The test statistics is based upon the variance of the amplitude of the weld voltage. The performance of the algorithm is evaluated using experimental data. The results obtained from the algorithm indicate that it is possible to detect changes in the weld quality automatically and on-line.
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| 10. |
- Agardh, Johannes, et al.
(author)
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Designing Future Interaction with Today's Technology
- 1999
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Other publication (other academic/artistic)abstract
- Information Technology has an increasing part of our lives. In this thesis we will discuss how technology can relate to humans and human activity. We take our standing point in concepts like Calm Technology and Tacit Interaction and examine how these visions and concepts can be used in the process of designing an artifact for a real work practice. We have done work-place studies of truck-drivers and traffic leaders regarding how they find their way to the right addresses and design a truck navigation system that aims to suit the truck drivers work practice.
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