Control System Designing For Correcting Wing-fuselage Assembly Deformation Of A Large Aircraft

Ensuring aerodynamic shape and eliminating assembly stress are the constant goals of aircraft assembly. The wing-fuselage assembly of a certain type aircraft is achieved by joining the joints of both docking gap and center wing box together, with the wing and fuselage being supported and aligned by multiple positioners. The docking gap of the center fuselage reduces the overall stiffness of the fuselage. The fuselage gravity load including landing gears causes deformation of assembly area under the supports of the positioners, thereby generating huge assembly stress. This paper introduces a hybrid force position control method for alignment system, implements deformation correction measure on the assembly area by cooperation motion of the positioners, thereby correcting assembly deformation and reducing assembly stress on the premise of ensuring aerodynamic shape. The paper’s content includes:Firstly, the recent foreign and domestic developments of alignment system are presented. The theory and approach for deformation correction and research status of aircraft assembly deformation correction are summarized. And the control methods of alignment system are introduced from the point of parallel mechanism.Secondly, the alignment process and components of alignment system are introduced. The cooperation motion control system based on SynqNet field bus is designed for multiple positioners. The wing-fuselage assembly deformation problem is raised by analyzing the wing-fuselage assembly process and the special structure of docking gap, and then the deformation correction method is proposed.Thirdly, the hybrid force position control system for correcting wing-fuselage assembly deformation is designed. The structure of hybrid force position control system is proposed. Force and position control axes of six fuselage positioners are selected based on screw theory and ellipsoid method. The position-control axes align the fuselage posture according to the posture trajectory. The force-control axes exert force on the fuselage according to the contact force derived by orthogonal experiments and partial least squares regression (PLSR), thereby correcting deformation of assembly area.Fourthly, the deformation correction effect of hybrid force position control method is studied by computer simulation technology. A simplified finite element model of fuselage is established in ABAQUS to simulate the hybrid force position control method. Simulation results show that the deformations of seven measurement points have been significantly improved. It proves that hybrid force position control method can correct the deformations and improve the wing-fuselage assembly quality.Fifthly, the deformation correction effect of hybrid force position control method is verified by actual experiments. The single axis control system is designed for actual assembly. The position controller and force controller are designed separately. One-dimension deformation correction experiment is conducted to correct the one-dimension deformation of specimen by hybrid force position control method. The experiment results show that one-dimension deformation of the specimen in hybrid force position control mode is significantly smaller than that in position-control mode, which proves the effect of hybrid force position control method.Finally, the research works of this paper are summarized and the further studies are prospected.