| 11. |
- Sikström, Fredrik, 1971-, et al.
(författare)
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3D-Scanning for Weld Distortion Measuring
- 2006
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Ingår i: Instrumentation and Measurement Technology Conference, 2006. IMTC 2006. Proceedings of the IEEE. - : IEEE conference proceedings. - 0780393600 - 0780393597 ; , s. 2132-2137
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Konferensbidrag (refereegranskat)abstract
- Optical three dimensional scanning for weld distortion measurements have been performed for validation, inspection, general visualization and documentation of a robotized welding process. The planning, preparing and processing of the weld is done in a simulation-based concept where computer aided robotics software simulations are integrated with finite element analysis simulations with the objective to reduce global geometrical deformation during welding. The off-line programmed robot paths were used as an input for finite element calculations of temperature fields and distortion in the work piece. In order to validate the finite element model 3D-scannings have been performed before and after every single welding sequence. This paper describes a validation experiment with non-contact measurements of weld distortion and discusses limitations in optical 3D-scanning techniques used for this purpose
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| 12. |
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| 13. |
- Sikström, Fredrik, 1971-, et al.
(författare)
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Simulated Feedback Control of Metal Fusion Welding
- 2007
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Ingår i: Proceedings of the ninth IASTED International Conference on Control and Applications. - : ACTA Press. - 9780889866652 ; , s. 2263-2270
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Konferensbidrag (refereegranskat)
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| 14. |
- Sikström, Fredrik, 1971-, et al.
(författare)
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Simulation for Design of Automated Welding
- 2007
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Ingår i: EUROCON, 2007. The International Conference on "Computer as a Tool". - : IEEE Explore. - 142440813X - 9781424408139 ; , s. 2263-2270
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Konferensbidrag (refereegranskat)abstract
- This paper describes a promising approach where simulations were used in the design of real-time control for automated welding. A finite element method has been used for thermal modelling of gas tungsten arc welding on a simplified test object. Measurement data for model calibration and validation was acquired through thermal imaging during weld experiments on test objects of the alloy Fe-316. An optimisation scheme for inverse modelling was employed in the calibration of the distributed weld process model. Frequency weighted model reduction and parametric system identification were applied and evaluated to get a low order model of the single-input single-output dynamics between a simulated weld heat source (actuator) and a sensor. This low order model was then successfully used for controller design where the control signal was weld current and the measured output was a moving spot temperature. Finally, the closed-loop performance was evaluated by simulation of the weld process model showing improved temperature stability relative to open loop.
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| 15. |
- Sikström, Fredrik, 1971-, et al.
(författare)
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Tools for simulation based fixture design to reduce deformation in advanced fusion welding
- 2008
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Ingår i: Intelligent Robotics and ApplicationsLecture Notes in Computer Science Volume 5315, 2008. - Berlin, Heidelberg : Springer. ; , s. 398-407
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Konferensbidrag (refereegranskat)abstract
- The traditional fusion welding and fixture simulations are performed using advanced finite element simulation tools, commonly used are e.g. MSC.Marc, ANSYS, ABACUS and COMSOL Multiphysics. These simulations are made one at a time and separately due to heavy calculation load for each case. Such an approach does not give a full description of the integrated work piece and fixture behaviour. We propose a strategy to decrease the computational time and solve the problem accurately enough for industrial needs. Focus of the simulation result is on residual deformation. The work piece is a simplified component composed by metal sheets, and rigid and loose clamping was investigated. Simulation results give the size of forces and deformations in the clamped edge. Deformation measurements are performed using 3D-scanning of the work piece after cooling and released from fixture, same situation as in the FE-simulations. The proposed strategy has shown to be useful and is industrially competitive due to reduced engineering manpower, computation time, and need for practical experiments. The strategy is to use full off-line programming where computer aided robotics for weld sequencies is integrated with finite element modelling in order to obtain weld parameters and fixture design.
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| 16. |
- Yücel, Baris, et al.
(författare)
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Automatic Generation of Multivariable Sampled-data Controllers for Jet-engines
- 2006
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Ingår i: Proceedings of Reglermöte 2006.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this contribution, it is shown how multivariable sampled-data controllers can be generated for a set of linearized models. The size of this set makes an automatic generation of controllers more practical and less time consuming. The control strategy is robust loopshaping according to Glover/McFarlane. The generated controllers are to be used for the military turbofan engine F404-RM12 which is currently used in the Swedish air fighter JAS39 Gripen.
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