Research On Techniques Of Aircraft Large Component Alignment For Coordination States Optimization

Aircraft assembly plays a great role in the aircraft manufacture,and it is the key and core technology of the aircraft manufacture.The large component joining is one of the main tasks in arcraft assembly.During the posture alignment of large component,it is not only necessary to ensure the relative posture accuracy of the large components,but also to ensure the coordination accuracy of the matching features,thereby maximizing the connection life and safety.Through the research of key problems in recent ten years,at present,China has a certain foundation of automatic alignment technology for large components,but there is less research on automatic alignment technology for the optimization of coordination states.Taking the coordination of intersection holes as an example,the large-scale measurement system such as the commonly used laser tracker has relatively large measurement uncertainty and tend to be blocked by the structures.Currently,the optimization of the coordination states still depends on the high-precision cylindrical plug gauge,and the posture of large component is fine-tuned by repeated trial and error.This process is less efficient,and easy to cause scratches on the hole wall.In order to comprehensively guarantee the posture and coordination accuracy of large components,and further improve the alignment efficiency and automation degree,this paper takes the wing to body joining with intersection holes as the research object,and makes an in-depth and systematic study on the evaluation and optimization of the uncertainty of large-scale measurement field,assemblyability evaluation and pre-alignment,vision based accurately measurement of hole poses,and fine-tuning of large component posture for coordination optimazaiton.The main contributions in this thesis are as follows:(1)A new ellipsoid model of measurement uncertainty is proposed for the spherical coordinate measuring systems(laser tracker,laser lidar,etc.).Compared with the existing models,it can more accurately express the spatial distribution of measurement uncertainty.A multi-station coordinate transformation algorithm considering both the layout and measurement uncertainty of the reference points is established,the least square adjustment solution along with variance-covariance matrix are derived.Aiming at the problem that the coordinate transformation uncertainty is large due to complex conditions such as the occlusion of reference points,a coordinate transformation uncertainty reduction method based on hybrid reference system is proposed.(2)The spatial anisotropy distributions of the tolerance domain and measurement uncertainty ellipsoid domain of key points are considered,the robustness evaluation functions of tolerance biases of position and symmetry of key points are established.On this basis,the robust evaluation model of component assemblyability driven by the uncertainty data is constructed,and simplex particle swarm optimization algorithm is introduced to determine the maximum confidence of assemblyability.(3)An on-line calibration algorithm of joint center coordinates is deduced,and the effects of the number of calibration adjustments and rotation angles on the calibration accuracy are analyzed,the large component posture is pre-aligned based on large-scale measurement.(4)Proposed a precise measurement method of intersection hole posture using monocular vision.The detailed image processing and ellipse fitting method based on the characteristics of intersection hole imaging is given.A rough estimation algorithm of posture based on the depth of hole and axis angle error is established.A posture optimization model based on forward mapping geometric distance error is constructed,and the M-estimation principle is introduced to optimize the solution,which reduces the influence of hole edge wear on the accuracy of pose measurement.(5)The metric of deviation between hole axles is established,and the distance between joint coordination faces is safetly evaluated.An optimization model of fine-tuning posture aiming for the coordination states optimization is developed while considering the attitude requrement of the component and the non-interference constraint between joint coordination faces.The solution process and constraint processing mechanism are given.In order to improve the accuracy of the solution,an analytical estimation algorithm for the initial value of fine-tuning posture based on Plück coordinate is derived.(6)On the basis of the above research,the system structure of the large component coordination states optimization system is proposed,and the functional planning of each parts of the system is carried out.Aiming at the application of coordination optimization on a certain type of wing-body joining with intersection holes,the engineering data set and process flow for wing-body coordination states optimization are established,the integrated control software for coordination states optimization is developed,and the alignment test platform is finally built to verify the coordination optimization accuracy.The optimization results of the actual alignment application are given,which proves that the proposed method can achieve a better balance of the pose accuracy and the coordination accuracy of the large components.