Adaptive NURBS-based trajectory optimization for robotic fiber placement on pressure vessels

Purpose The purpose of this study is to address roller-mandrel interference, abrupt orientation changes, and trajectory discontinuities during fiber placement on complex pressure-vessel surfaces. To this end, a trajectory optimization method based on Non-Uniform Rational B-Splines (NURBS) interpolation and S-curve velocity planning is proposed to improve trajectory continuity, pose synchronization, and execution accuracy. Design/methodology/approach First, by integrating pressure-vessel geometric modeling with the constraints of the polar-hole region, a roller–interference optimization strategy is developed to correct both the position and orientation of key path points. Second, an adaptive step-size NURBS interpolation method is introduced in the coupled position–orientation space. Under the constraints of chord error and centripetal acceleration, closed-loop accuracy feedback effectively reduces data volume and improves computational efficiency. Finally, a seven-segment S-curve-based velocity planning model is constructed to ensure smooth transitions of segmented trajectories in terms of velocity, acceleration and jerk, thereby guaranteeing pose synchronization and stable trajectory execution. Findings Simulation and experimental results demonstrate that, while maintaining interpolation accuracy, the proposed method reduces the data volume by an average of 67.73% and shortens the iteration cycle by 73.64%, significantly enhancing path continuity and pose synchronization. In complex pressure-vessel fiber placement experiments, it achieves interference-free operation, smooth transitions and high-precision trajectory execution. Research limitations/implications The proposed method is developed and validated based on specific geometric models and controlled experimental conditions. Its performance may be influenced by variations in surface complexity, material properties, and real-world manufacturing disturbances. Further research is required to extend the method to more complex geometries and to evaluate its robustness under practical industrial conditions. Originality/value The proposed method satisfies the pose-accuracy requirements of automatic fiber placement on complex curved surfaces, providing reliable and precise technical support for the efficient manufacturing of composite pressure vessels, and thereby delivering significant engineering application value.