Adaptive Control of Weld Penetration by Detecting Oscillation and Shape of the Weld Molten Pool

本年度建立了薄板对接焊焊缝熔深的鲁棒识别与控制系统。该系统实现了熔池形状的识别和熔池振荡频率的检测。此外，为了在不改变焊接条件（如坡口形状、坡口间隙等）的情况下获得良好的焊缝，构建了焊接过程中的焊接现象诊断和焊接条件控制系统。(1)构建了一个智能焊接机器人系统，该系统具有视觉传感器，可观察焊接熔池的形状和尺寸，包括长度、宽度和面积。(2)建立了一种通过控制焊接熔池尺寸来实现焊缝熔深最优控制的自适应控制系统。(3)提出了一种基于人工神经网络的自适应控制系统。该系统的输入层为焊缝长度、宽度、面积、焊接速度、焊接电流和根部间隙等六个单位，输出层为焊接电流变化的七个单位，隐层为八个单位。(4)采用脉冲电流作为焊接电流，在基值电流时间内检测电弧电压的振荡，可以检测到熔池振荡的频率。(5)利用熔池特征频率检测原理，建立了一套熔透焊接控制系统。(6)采用TIG电弧焊方法进行了低碳钢板的焊接试验。所构建的焊接控制系统的有效性得到了证实。

In this year, a robust control system for recognizing and controlling the penetration of the weld in butt welding of thin steel plates was constructed. In this system, the recognition of the molten pool shape and detection of peculier frequency of molten pool oscillation were performed. Furthermore, in order to obtain sound weld regardless change of welding conditions, such as groove shape, gap of groove and so on, system to diagnose the welding phenomena during welding and to control welding conditions were constructed.Main results obtained are summarized as follows.(1) An intelligent welding robot system with vision sensors that observe the shape and dimensions of the weld molten pool, including length, width and area was constructed.(2) An adaptive control system to optimumly control the penetration of weld by controlling the dimensions of the weld molten pool was constructed.(3) An adaptive control system using Artificial Neural Network was proposed. lt has an input layer of six units for length, width, area, welding speed, welding current and root gap of welding line, an output layer of seven units that indicates change of welding current, and an hidden layer of eight units.(4) Applying pulse current as welding current and detecting oscillation of arc voltage during base current time, the frequency of the oscillation of molten pool can be detected.(5) A system to control penetration welding using the principle to detect the peculiar frequency of molten pool was constructed.(6) Mild steel plate welding experiments using TIG arc welding method were performed. The effectiveness of the constructed welding control systems was confirmed.