Fuzzy seam-tracking controller

The welding spot of an automatic laser welding system is very small, thus requiring real-time accurate control of the welding position. The author has developed a seam-tracking controller that uses fuzzy logic. This controller incorporates an operator´s seam recognition ability and uses a method for auto-tuning the fuzzy rules. The major difficulty of an optical sensing seam tracking controller is to estimate the seam location from an image which may be graded by changes in the workpiece´s surface condition. The inference rule for seam detection using fuzzy logic can incorporate ambiguous descriptions. It can be used to infer the appropriate seam location from a graded image which does not exactly match the rules