基于复合传感的GTAW三维焊缝位姿跟踪

发布时间：2018-03-06 21:26

本文选题：薄板对接　切入点：复合传感　出处：《南昌航空大学》2015年硕士论文　论文类型：学位论文

【摘要】：在实际焊接过程中,存在着各种不确定的干扰因素,例如加工和装配误差及焊接过程的热应力引起的变形等,往往造成焊缝的位置和尺寸发生变化,导致焊接轨迹与焊缝产生偏差,从而影响焊接质量。焊接条件的这种变化要求焊接设备能够实时检测轨迹偏差并调节焊接路径,因此研究焊缝跟踪技术对提高焊接自动化水平具有重要意义。本文针对薄板对接接头,研究了基于复合传感的GTAW焊缝位姿跟踪技术。设计了被动视觉传感器,通过试验和分析,选用了合适的复合滤光系统,并获取了特征清晰、稳定的焊接图像。针对采集到的图像,提出了一套完整的新型图像处理算法,能够准确地提取钨极中心投影位置及焊缝中心线方程。利用电弧传感器,有效地采集GTAW弧压信号,通过防脉冲干扰滑动均值法消除了焊接过程中干扰噪声对弧压信号的影响。在此基础上,建立了弧压与弧长的关系模型。采用上述复合传感系统获取了更可靠、更全面的薄板对接焊缝的形貌信息,能够有效地提取焊枪与焊缝的横向和纵向位置偏差,为实现焊缝三维位置跟踪奠定了基础。此外,研究了焊枪行走角的姿态跟踪,利用复合传感系统获取了焊缝路径点的位置及焊枪的姿态信息,提出了一种局部焊缝模型的建立方法,从而提取了焊枪姿态的偏差特征。在提取位姿偏差的基础上,设计了Fuzzy-P复合控制器对焊缝跟踪进行控制。在大偏差范围内,采用比例控制提高系统的响应速度;在小偏差范围内,选用模糊控制器进行跟踪控制。通过MATLAB仿真试验表明,所设计的控制器具有可靠性好的优点,满足GTAW焊缝跟踪的控制要求。在Windows XP系统平台下采用Visual C++多线程技术开发了焊缝跟踪系统软件。该系统包括一个主线程和三个子线程,主线程主要负责系统硬件的初始化,子线程分别负责焊缝图像的采集和处理、电信号的采集和处理及焊枪行走角偏差的提取。为了验证系统的实用性,利用所设计的GTAW焊缝跟踪系统进行薄板对接跟踪试验。试验结果表明,三维位置跟踪偏差能够控制在±0.4mm以内,而焊枪行走角的姿态跟踪处于探索阶段,跟踪的精度还有待进一步的研究和改善。
[Abstract]:In the actual welding process, there are various uncertain interference factors, such as machining and assembly error and deformation caused by thermal stress in welding process, which often result in the change of welding seam position and size. The variation of welding conditions requires that the welding equipment can detect the trajectory deviation and adjust the welding path in real time. Therefore, it is very important to study the welding seam tracking technology to improve the level of welding automation. In this paper, the GTAW welding seam position and attitude tracking technology based on composite sensing is studied, and the passive vision sensor is designed, which is tested and analyzed. The suitable composite filter system is selected, and the welding image with clear and stable characteristics is obtained. A new image processing algorithm is proposed for the collected image. The center projection position of tungsten electrode and the equation of weld centerline can be accurately extracted. The arc voltage signal of GTAW can be effectively collected by using arc sensor. The influence of interference noise on arc voltage signal in welding process is eliminated by means of anti-pulse interference sliding mean method. On this basis, a relationship model between arc voltage and arc length is established. More comprehensive profile information of butt welding seam of thin plate can effectively extract the transverse and longitudinal position deviation between welding torch and weld seam, which lays a foundation for realizing 3D position tracking of welding seam. In addition, the attitude tracking of walking angle of welding torch is studied. The position of weld path point and the attitude information of welding torch are obtained by using the compound sensing system, and a method of establishing local welding seam model is proposed to extract the deviation feature of welding torch attitude. The Fuzzy-P composite controller is designed to control the seam tracking. In the large deviation range, the proportional control is used to improve the response speed of the system. In the small deviation range, the fuzzy controller is used to control the seam tracking. The MATLAB simulation results show that, The designed controller has the advantages of good reliability and meets the control requirements of GTAW weld seam tracking. The software of the weld seam tracking system is developed by using Visual C multithreading technology under the Windows XP system platform. The system includes one main thread and three sub-threads. The main thread is mainly responsible for the initialization of the system hardware, the sub-thread is responsible for the collection and processing of the weld image, the acquisition and processing of the electric signal and the extraction of the walking angle deviation of the welding torch respectively. The thin plate butt tracking test is carried out by using the designed GTAW welding seam tracking system. The experimental results show that the 3D position tracking deviation can be controlled within 卤0.4 mm, while the attitude tracking of the walking angle of the welding torch is in the exploratory stage. The precision of tracking needs further research and improvement.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG409

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