基于Hammerstein模型的GMAW-P焊接熔深自适应预测控制

针对脉冲熔化极气体保护焊(Pulsed gas metal arc welding,GMAW-P)过程中焊接熔深的实时控制，使用脉冲峰值期间的电压变化幅值(ΔU)来表征焊接熔深变化，并且通过测量和控制ΔU的大小来间接达到熔深控制的目的。建立了以ΔU为输出和脉冲基值电流为输入的单输入单输出熔深控制系统。系统输入输出之间的静态关系模型显示该熔深控制系统具有一定非线性，因此，采用加入干扰的Hammerstein模型描述该非线性系统。在基于该Hammerstein模型的经典预测控制算法基础上，在控制过程中加入递推最小二乘法在线辨识模型参数，从而实现焊接熔深自适应控制。控制算法仿真和实时焊接试验表明该熔深控制算法能够较好地实现GMAW-P焊接过程中的熔深控制。变散热试验结果验证了该控制算法的有效性和适应性。

Adaptive Predictive Control of Weld Penetration Depth Based on Hammerstein Model in Pulsed Gas Metal Arc Welding

To control weld penetration depth in real time in pulsed gas mental arc welding (GMAW-P) process, the voltage variation amplitude during a peak current period (ΔU) is proposed to characterize the change in weld penetration depth, and ΔU is measured and controlled to control weld penetration depth in GMAW-P process. A single input and single output system is established with ΔU as system output and base current as system input for the weld penetration depth control. The static model between the input and output of the system shows that the weld penetration depth control system has nonlinearity, which can be described by the Hammerstein model with the interference. The recursive least square method is added in classical predictive control algorithm, which is established based on the Hammerstein model, to identify the system model parameters online and to achieve adaptive control of the weld penetration depth. The control algorithm simulation results and the real time welding experiments prove that the adaptive predictive control algorithm can well control the weld penetration depth in GMAW-P process. The effectiveness and adaptability of the control algorithm are verified by variable heat dissipation experiments.