A Study on Force/Position Hybrid Control Strategy for Eight-Axis Robotic Friction Stir Welding
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In aerospace and new-energy vehicle manufacturing, there is a growing need for high-quality joining of large, curved aluminum alloy structures. This study proposes a robotic friction stir welding (RFSW) system employing force/position hybrid control. An eight-axis linkage platform integrates an electric spindle, multi-dimensional force sensors, and a laser displacement sensor, ensuring precise robot–positioner trajectory coordination. By combining large-range constant displacement with small-range constant pressure—supplemented by an adaptive transition algorithm—the system regulates axial stirring depth and downward force. Experiments confirmed that this approach effectively compensates for robotic flexibility, keeping weld depth and pressure deviations within 5% and significantly improving seam quality. Further welding verification was conducted on typical curved panels for aerospace applications, results demonstrated strong adaptability under high-load, multi-DOF conditions with no observed cracks. This research could support advance the field toward more robust, automated, and adaptive RFSW solutions for aerospace, automotive, and other high-end manufacturing applications.