Model reference adaptive control scheme for enhancing bead width and depth of penetration during cold metal transfer process
01 Dec 2017-
TL;DR: The simulation results indicate that the designed MRAC for CMT process successfully maintained the welding current at the set point when subjected to short circuit and arcing phases whereas the conventional PID controller is unable to retrieve the weldingCurrent at set point.
Abstract: This paper presents an adaptive welding control scheme for the Cold Metal Transfer process (CMT) deployed for joining Aluminium 6061 alloy sheets. The mathematical model of the CMT welding control system is derived and the plant model is estimated using system identification technique. A Model Reference Adaptive Controller (MRAC) is designed to maintain the desired welding current during the occurrence of electrode wire short circuiting and melting during the joining process. The proposed adaptive control method is compared with that of the conventional PID controller for the performance analysis. The simulation results indicate that the designed MRAC for CMT process successfully maintained the welding current at the set point when subjected to short circuit and arcing phases whereas the conventional PID controller is unable to retrieve the welding current at set point. The experimental validation using the designed MRAC is carried out in the CMT welding set up. The experimental results agree with the simulation results and emphasizes that the MRAC improves the welding performance by yielding good weld joints at requisite time and quality.
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TL;DR: In this paper, the porosity of AA2219-T851 high strength aluminum alloy welds with ER2319 wire produced by different cold metal transfer (CMT) processes and heat inputs were investigated.
71 citations
"Model reference adaptive control sc..." refers methods in this paper
...analysis is on weld bead geometry, porosity and heat inputs of aluminum alloys joining using CMT welding process [14]....
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TL;DR: In this paper, the effect of welding current and welding speed on heat input, depth of penetration, weld pool width, reinforcement height, dilution, weld bead contact angle parameters during cold metal transfer (CMT) process is investigated.
60 citations
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...00 ©2017 IEEE which melts the electrode wire [3]....
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TL;DR: In this article, the use of adaptive schemes for on-line control of backbead width in the Gas Tungsten Arc (GTA) welding process has been investigated and two adaptive controllers, model-referenced adaptive control (MRAC/NL) and self-tuning control with pole placement (STC/PP), were evaluated.
Abstract: This study addresses the uses of adaptive schemes for on-line control of backbead width in the Gas Tungsten Arc (GTA) welding process. Open-loop tests using a step input current confirm the validity of a nominal first order process model. However, the time constant and gain prove highly dependent upon welding conditions including torch speed, arc length, material thickness, and other material properties. Accordingly, a need exists for adaptive controllers that can compensate for these process nonlinearities. The performance of two adaptive controllers is evaluated: Narendra and Lin’s Model-Referenced Adaptive Control (MRAC/NL), and Self-Tuning Control with Pole Placement (STC/PP). The addition of a quadratic term to the adaption mechanisms of MRAC/NL is proposed and preliminary simulations and experiments clearly demonstrate the stabilizing effect of this added term. The main experiments compare the performance of the modified MRAC/NL controller and the STC/PP controller with each other and with linear PI controller and the STC/PP controller with each other and with linear PI controller under four experimental conditions: first, where welding conditions are nominal; second, when conditions are disturbed by a step-wise increase in the torch velocity, and third, when conditions are disturbed by a step-wise increase in material thickness. In each case the experimental demonstrates the superiority of the adaptive controllers over the linear PI controller. However, the STC/PP controller exhibits high frequency control action in response to severe disturbances of material thickness and the parameter estimates it generates drift during steady-state operations. The MRAC/NL controller proves more robust under these circumstances. Analysis demonstrates that the superior performance of the MRAC/NL is due both to the inherent normalizing effect of the quadratic feedback terms and to the noise filtering properties of the adaptive mechanism.
43 citations
"Model reference adaptive control sc..." refers methods in this paper
...The performance of the MRAC is compared with conventional PI controller at various conditions and resulted that MRAC is robust in all circumstances [11]....
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TL;DR: Experimental results presented include characterization of plant uncertainty and of the effect in control performance of various available knobs, in particular in the presence of plates with variable geometry.
Abstract: This application paper addresses the use of adaptive predictive control on arc welding trailing centerline temperature control. For tackling the high level of uncertainty in the process the multivariable multipredictive adaptive regulator (MUSMAR) adaptive algorithm, relying on separate estimation of predictive models is used. Experimental results presented include characterization of plant uncertainty and of the effect in control performance of various available knobs, in particular in the presence of plates with variable geometry.
37 citations
"Model reference adaptive control sc..." refers background in this paper
...paper addresses the use of adaptive predictive control on arc welding trailing centerline temperature control, for tackling high level uncertainties in arc welding processes [12]....
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TL;DR: An explanation of the toolbox's design and use is provided together with an overview of the underlying supported models and algorithms to streamline comparisons.
31 citations