Research On Estimation Method For Key Geometric Features Of Tooling Positioner In Aircraft Assembly

With the development of modern aviation technology,large aircraft plays an increasingly important role in the field of public transportation and national defense security,and the requirements for aircraft manufacturing level are also more stringent.Aircraft assembly is an important stage of aircraft manufacturing,and its precise execution is an important guarantee for aircraft service performance and structural safety.Aircraft tooling is used as the positioning datum in the assembly process,and the high precision measurement of the key axis and shape position of each positioner is very important to improve the assembly quality of aircraft.Due to improper assembly operation,the key geometric features of the tooling positioner are deviated,which seriously affects the precision of the tooling,causes assembly out of tolerance,and then affects the manufacturing precision and quality of the aircraft.At the same time,the shaded measuring environment at the assembly site leads to the inability to directly detect the key geometric features of the tooling positioner.Therefore,it is of great significance to study the estimation for the key geometric features of the tooling positioner in the process of aircraft assembly to improve the quality of aircraft manufacturing.In this paper,the estimation method for the key geometric features of the tooling positioner in the process of aircraft assembly is studied.The main research contents are as follows:(1)Aiming at the problem that the key geometric features of the tooling positioner cannot be measured directly,a key geometric feature estimation method based on finite monitoring point information under rigid hypothesis was proposed.Firstly,the off-line relational model calibration method between the monitoring points of the tooling positioner and the key geometric features is proposed,and the fitting algorithms of the two key geometric features are deduced.Finally,the offline relationship model between the monitoring points and the key geometric features is obtained through calibration experiments,which provides data support for the subsequent in-situ estimation of the key geometric features of the tooling positioner.(2)To meet the requirement of online measurement of key geometric features of tooling positioner in assembly process,an in-situ estimation method of key geometric features of tooling positioner was proposed.Firstly,the principle of binocular photogrammetry is expounded.Secondly the advantages and disadvantages of the four transformation matrix solving algorithms are analyzed and the experimental verification is carried out to obtain the optimal algorithm.Aiming at the key geometric features of the tooling positioner,the precision evaluation method suitable for in-situ estimation of the key geometric features of the tooling positioner was determined.(3)A deformation prediction model based on sample clustering weighted support vector machine(WSVM)was proposed to compensate the elastic deformation of the tooling positioner.The real-time deformation information acquisition program of tooling positioner was developed to obtain the deformation information of positioner monitoring points and key geometric features,and the input and output sample data required by the model were constructed.The influence of kernel function and model parameters on the deformation prediction model was analyzed,and the efficiency and performance of various parameter optimization methods were compared.The optimal parameter optimization method was selected to obtain the optimal parameter combination,and then the model was trained.(4)Based on the above research,the estimation accuracy of the front girder positioner,the front girder auxiliary positioner,the actuator positioner and the hinge hole positioner under the rigid hypothesis and elastic deformation compensation is experimentally studied.The results show that the coaxiality of the positioning axis(less than Φ0.15mm)and the plane position of the positioning plane(less than 0.1mm)are both satisfied in the two cases.The effectiveness of the proposed method for estimating the key geometric features of the tooling positioner in the aircraft assembly process is verified.