Online Extraction of Pose Information of 3D Zigzag-Line Welding Seams for Welding Seam Tracking

Three-dimensional (3D) zigzag-line welding seams are found extensively in the manufacturing of marine engineering equipment, heavy lifting equipment, and logistics transportation equipment. Currently, due to the large amount of calculation and poor real-time performance of 3D welding seam detection algorithms, real-time tracking of 3D zigzag-line welding seams is still a challenge especially in high-speed welding. For the abovementioned problems, we proposed a method for the extraction of the pose information of 3D zigzag-line welding seams based on laser displacement sensing and density-based clustering point cloud segmentation during robotic welding. after thee point cloud data of the 3D zigzag-line welding seams was obtained online by the laser displacement sensor, it was segmented using theρ-Approximate DBSCAN (Density-Based Spatial Clustering of Applications with Noise) algorithm. In the experiment, high-speed welding was performed on typical low-carbon steel 3D zigzag-line welding seams using gas metal arc welding. The results showed that when the welding velocity was 1000 mm/min, the proposed method obtained a welding seam position detection error of less than 0.35 mm, a welding seam attitude estimation error of less than two degrees, and the running time of the main algorithm was within 120 ms. Thus, the online extraction of the pose information of 3D zigzag-line welding seams was achieved and the requirements of welding seam tracking were met.

Ram cult of funnel beaker culture tribes

Among the variety of clay products of the Funnel beaker culture, there is almost no zoomorphic plastic. Such items include the handle of the vessels in the form of realistically shaped heads of the ram. And it is the only animal in the Funnel beaker culture, which is somehow expressed. Vessels with handles in a shape of rams and their fragments were found in a small amount. On the large territory, occupied by southeastern group of Funnel beaker culture and where hundreds of settlements are known, most of which were excavated only 60-70 figures were found in twenty sites. On some settlements many of such items were collected. For example, in Gródek (about 30), Zymno (18), Ćmielów (over 10) and on the others – only single finds. Also, on the many capitally examined sites such artifacts are absent. The rams decorated only the handles of jugs and pots. These vessels are usually ornamented. The ornament is constructed according to a clear scheme of world tree: rims are decorated with zigzag line, characteristic for ritual zoomorphic vessels of several agricultural cultures and interpreted as symbol of water. Side walls of the body are ornamented by a vertical ladder, which can be interpreted as grain ear. Paired handles in shape of rams, joined by sacred yoke which embodied sacral content of fertility. Most of the products, usually jars, were found in the storage pits, and some of the pots were found in women's graves. On the settlement of Zymno all figures were found in cultural layers and situated in separate concentrations. Such vessels were sacred – intended for the storage and sowing of grain, as well as for the ritual of praying for rain. Among ancient agricultural tribes, some animals, including ram, embodied the fertility cult and identified with certain forces of nature. The origins of the ram cult in the southeastern group of tribes of Funnel beaker culture are obviously can be found among its nearest neighbors, perhaps Trypillians, where such practices were more advanced. Key words: Funnel Beaker culture, ram cult, ritual, ornament, grain, water.