Abstract: The trackless crawling welding robot moves freely and flexibly,which leads to the low seam tracking accuracy of the active visual sensing method with advanced monitoring errors.The passive vision sensing method has no advanced monitoring error,but requires the use of an expensive molten pool camera,resulting in increased equipment costs.Aiming at these problems,a visual acquisition system composed of dual cameras was designed,and a method for measuring the welding deviation of the simultaneous collection of droplets and welds was proposed.The image of the droplet and weld were calibrated separately,and then the image information of the droplet and weld were merged into the same image coordinate system.Then,the method of pit area detection was used to locate the tip of the welding wire in the droplet image.In addition,the straight line of the weld edge was fitted using the least square method.The positional relationship between the tip of the welding wire and straight line of the weld edge was employed to calculate the current welding deviation in the established welding deviation measurement model.The experimental results showed that welding error could be controlled within 0.2mmapplying the droplet-weld synchronous vision method,which had a higher weld tracking accuracy and important application prospects.

Key words: trackless crawling welding robot, synchronous vision, molten drop, weld tracking, pit detection

摘要： 由于无轨爬行式焊接机器人运动方式自由灵活,导致存在超前监测误差的主动视觉传感方法焊缝跟踪精度不高。被动视觉传感方法无超前监测误差,但需采用昂贵的熔池相机,从而导致设备成本增加。针对以上问题,设计了一种由双摄像机组成的视觉采集系统,并提出一种熔滴—焊缝同步采集焊接偏差测定方法。首先,通过标定分别校正熔滴和焊缝图像,然后将熔滴、焊缝图像信息融合到同一图像坐标系中。进一步,采用凹点区域检测方法定位熔滴图像中的焊丝尖端,并采用最小二乘法拟合焊缝边缘直线。最后,利用焊丝尖端与焊缝边缘直线的位置关系,在已建立的焊接偏差量测定模型中计算出当前时刻焊接偏差量。实验结果表明,在实验室环境下,采用熔滴—焊缝同步视觉方法,焊接误差可以控制在0-2 mm以内,具有较高焊缝跟踪精度和重要应用前景。

关键词: 无轨爬行式焊接机器人, 同步视觉, 熔滴, 焊缝跟踪, 凹点检测