Design and Implementation of a Nonlinear Axial Force Controller for Friction Stir Welding Processes
Design and Implementation of a Nonlinear Axial Force Controller for Friction Stir Welding Processes
复制标题
搅拌摩擦焊过程非线性轴向力控制器的设计与实现
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
K. Krishnamurthy
中科院分区：
文献类型：
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作者：
Xin Zhao;Prabhanjana Kalya;R. Landers;K. Krishnamurthy
在搅拌摩擦焊接(FSW)过程中，轴向力提供了锻造作用，影响了零件的微观结构，从而影响了零件的机械性能。控制此力可提供良好、一致的焊接质量。本文的目的是为设计和实现搅拌摩擦焊过程的轴向力控制器提供一种系统的方法。轴向力被建模为所测量的FSW工艺参数(即沉入深度、横移速度和转速)的非线性函数，设备被建模为从命令到所测量的工艺参数的纯延迟。基于这些动力学模型，采用多项式极点配置方法设计了轴向力的非线性反馈控制器。该控制器以Smith预估器-校正器结构实现，以补偿固有的设备延迟，并在给定设备限制的情况下调整控制器参数以获得最佳的闭环系统响应。实验证明，即使在焊接过程中遇到间隙，控制器也能够保持恒定的轴向力。
In Friction Stir Welding (FSW) processes the axial force provides a forging action that affects the part's micro structure and, hence, its mechanical properties. Controlling this force provides good, consistent welding quality. The aim of this paper is to provide a systematic method to design and implement axial force controllers for FSW processes. The axial force is modeled as a nonlinear function of the measured FSW process parameters (i.e., plunge depth, traverse rate, and rotation speed) and the equipment is modeled as a pure delay from the commanded to the measured process parameters. Based on these dynamic models, a nonlinear feedback controller for the axial force is designed using Polynomial Pole Placement. This controller is implemented in a Smith Predictor-Corrector structure to compensate for the inherent equipment delay and the controller parameters are tuned to achieve the best closed-loop response given the equipment limitations. Experimental implementations verify the controller is able to maintain a constant axial force, even when gaps are encountered during the welding process.