Control of DE-GMAW through human–robot collaboration

Abstract

Double-electrode gas metal arc welding (DE-GMAW) modifies conventional gas metal arc welding (GMAW) by adding a second electrode, allowing part of the current to flow directly from the wire back to the power supply. This configuration reduces the current flowing to the workpiece compared to that at the wire, and this reduction is freely controllable. This unique ability to separately control mass and heat input is particularly advantageous for applications requiring flexible heat management, such as additive manufacturing. In this innovative process, the positioning of the bypass electrode relative to the wire tip is critical for maintaining a stable arc and optimal metal transfer; however, designing an effective positioning rule can be tedious and challenging. A general solution is human–robot collaboration (HRC), which enables humans to directly operate robots and serves as real-time optimizers that can quickly develop effective rules through a few trials. Additionally, HRC allows for learning from human operation data to fully automate these rules. In this work, we designed a dual-robot HRC system that enables operators to make stable, real-time adjustments to electrode positions with ease. The HRC system incorporates a virtual reality (VR) environment, providing immersive, real-time process visualization to assist operators in accurately and safely perceiving the welding state. Efficient teleoperation of DE-GMAW is achieved by integrating high-quality camera visuals and precise robotic execution into a VR environment, eliminating hazards associated with on-site manual welding, such as welding fumes, arc radiation, and electric shock, while enhancing observation and operational accuracy. Experiments were conducted to evaluate the system’s capability to support fast and precise human adjustments, demonstrating the effectiveness of the proposed system in implementing DE-GMAW. Furthermore, full automation provides a pathway for transitioning DE-GMAW into manufacturing applications.