Automatic Adaptive Weld Seam Width Control Method for Long-Distance Pipeline Ring Welds.

Area of Science:

• Robotics and Automation
• Materials Science and Engineering
• Welding Technology

Background:

• Conventional methods for welding torch control struggle with pseudo-inflection points in bevel geometry.
• Accurate real-time geometric data is crucial for controlling torch swing in all-position welding.

Purpose of the Study:

• To develop a novel algorithm for precise identification of bevel inflection points in variable-width pipe welding.
• To enhance the dynamic performance and adaptability of welding torch swing control systems.

Main Methods:

• A third-order derivative weighted average threshold algorithm was developed, incorporating image processing and cubic spline fitting.
• Dual-angle sensors were used to synchronize laser-detected geometry with real-time torch adjustments.
• The algorithm utilizes extracted second-order derivative eigenvalues to derive third-order derivative features for inflection point identification.

Main Results:

• The system achieved a steady-state error of 1.645% and a dynamic response time under 50 ms.
• Torch center trajectory tracking errors were constrained within ±0.1 mm.
• The proposed algorithm demonstrated a 20.6% improvement in dynamic performance over conventional methods and adaptability to narrow-gap V-grooves.

Conclusions:

• The developed algorithm provides real-time, accurate control for variable-width weld tracking.
• A swing-width adaptive control system was successfully established for pipeline welding.
• The method offers superior performance and adaptability compared to existing techniques.