Article A Fully-Actuated Pose Adjustment Method for Wing-Fuselage Assembly Based on Global Gap Optimization Using Measured 3D Point Clouds

Abstract

Wing-fuselage assembly is a critical process in aircraft manufacturing, and the gap distribution of the wing-fuselage assembly frames directly determines the stress state of the connection interface and the structural load-carrying capacity after assembly. However, most existing pose adjustment methods either do not consider the global gap distribution or optimize the gap only based on theoretical CAD models, making it difficult to effectively control the actual gap distribution under real manufacturing errors. In addition, traditional positioners adopt a master-slave driving mode, in which passive axes suffer from following errors due to the lack of independent control, thereby limiting the execution accuracy of pose adjustment. To address these problems, this paper proposes a fully-actuated pose adjustment method based on global gap optimization using measured 3D point clouds. First, point cloud data of the wing-fuselage assembly frames in a unified assembly coordinate system are obtained through laser scanning combined with ERS reference point registration. Assembly gaps are then defined along the theoretical assembly-surface normals, and a multi-surface global gap evaluation model is established. Second, a two-stage optimization strategy combining coarse alignment and fine adjustment is adopted, in which assembly-depth correction is decoupled from gap-uniformity rotation optimization to solve the optimal target assembly pose. Finally, the optimized pose is converted into multi-axis synchronous motion commands for fully-actuated positioners through fifth-order polynomial trajectory planning and inverse kinematic mapping, and the force-position data of the positioners are effectively monitored throughout the pose adjustment process. The proposed method is compared with a traditional manual assembly method on a wing-fuselage assembly experimental platform. The results show that the proposed method reduces the in-plane gap standard deviations of the upper and right assembly surfaces from 2.19 mm and 1.34 mm to 1.70 mm and 1.04 mm, respectively, significantly improving gap uniformity. Meanwhile, the positioner motion remains continuous and smooth during pose adjustment, and no abnormal force fluctuations occur at the support points. The proposed method provides a reliable integrated solution for high-precision wing-fuselage assembly and gap control of aircraft components.