The Active Visual Sensing Methods for Robotic Welding: Review, Tutorial, and Prospect

The visual sensing system is one of the most important parts of the welding robots to realize intelligent and autonomous welding. The active visual sensing methods have been widely adopted in robotic welding because of their higher accuracies compared to the passive visual sensing methods. In this article, a comprehensive review of the active visual sensing methods for robotic welding is given. According to their uses, the state-of-the-art active visual sensing methods are divided into four categories: seam tracking, weld bead defect detection, 3-D weld pool geometry measurement, and welding path planning. First, the principles of these active visual sensing methods are reviewed. Then, a tutorial on the 3-D calibration methods for the active visual sensing systems used in intelligent welding robots is given to fill the gaps in the related fields. At last, the reviewed active visual sensing methods are compared and the prospects are given based on their advantages and disadvantages.