Application of Vision Sensor to Seam Tracking of Butt Joint in Container Manufacture
Pp. 56-82 (27)
Zao Jun Fang and De Xu
This chapter designs a vision-based seam tracking system for butt joint of thin plate. Image-based
visual control method is adopted due to its many merits. A key feature of this system is that it is compact and
reliable. Smart camera is selected as the vision sensor and programmable logic controller (PLC) as the controller.
Since the seam is so narrow, the visual measurement is based on natural lighting. To effectively extract the image
features, “and” operation is proposed to eliminate the effect of splash of welding. Moreover, a new adaptive
thresholding method is presented to segment the seam from the image, and combination of Hough transform and
least square line fitting technique is used to extract the seam line. In terms of controller, a novel method is
proposed to define reference and feedback image features to form a closed loop in image space. In addition,
image error filtering and output pulse verification are added to the controller to improve the reliability. Finally, a
series of experiments were conducted to verify the performance of the proposed seam tracking system.
Vision sensor, seam tracking, butt seam, image-based visual control, PLC.
The Key Laboratory of Complex System and Intelligence Science, Institute of Automation, Chinese Academy of Sciences, Beijing, 100190, P.R. China.