Research On The Docking Pose Measurement Method Of Large Aircraft Components Based On Draw-wire Displacement Sensor

Digital measurement technology is one of the core technologies for the automatic assembly and docking of large aircraft components,and it guarantees the accuracy of assembly and docking.Commonly used non-contact digital measurement devices such as laser trackers and i GPS are susceptible to environmental factors such as light path obstruction.In order to improve the efficiency and reliability and reduce the cost of assembly docking,a method for measuring the position and attitude of large aircraft parts docking based on the draw-wire displacement sensor is proposed,and the position and attitude of large parts are solved by using BP neural network and Newton’s method.The main research content of this article is as follows:Firstly,a novel method for measuring the docking position of large aircraft components based on a draw-wire displacement sensor is proposed.The large aircraft parts attitude measurement field is constructed with six sets of draw-wire displacement sensors,and the principle of attitude measurement is studied.The large aircraft component docking attitude measurement scheme based on the draw-wire displacement sensors and the layout of the sensor is designed,and the theoretical model of the aircraft large component attitude and rope length value of the draw-wire displacement sensors is established.Secondly,a hybrid algorithm based on BP neural networks and Newton’s iterative method is used to solve for the docking position of large aircraft components.The BP neural network structure with a different number of nodes and hidden layers is designed.The theoretical model of the large aircraft component position and the rope length value of the draw-wire displacement sensor is used to establish the sample data of the BP neural network,the training test of the designed BP neural network structure is completed and the optimal network structure model is analyzed.A theoretical model is established to solve aircraft large component poses by Newton’s iterative method.Based on the optimal BP neural network structure model to predict the aircraft’s large component attitude,the predicted attitude is used as the initial value of Newton’s iterative method to solve the attitude,and the error of the hybrid algorithm based on BP neural network and Newton’s iterative method to solve the attitude is analyzed.The numerical simulation results show that the maximum absolute value of position error is 7.0616×10^-7mm,the maximum absolute value of attitude angle error is 1.9959×10^-9°,the maximum iteration time is 0.589453s,the maximum number of iteration steps is 10,in the 20 sets of large part positional solutions.The effectiveness of the hybrid algorithm for solving the docking attitude of large aircraft components is verified.Finally,the aircraft large component docking attitude measurement experimental platform is designed and constructed.The design of the aircraft’s large component docking attitude measurement experimental process is completed,and experiments of attitude measurement based on the draw-wire displacement sensor are completed.The experimental results show that the maximum position error is 0.6031mm and the maximum error in attitude angle is 0.0882°.The main errors of the aircraft’s large component docking attitude measurement method and system based on the draw-wire displacement sensor are analyzed.An error model of the aircraft’s large component docking attitude measurement system is developed and the theoretical error of the attitude measurement experiment is calculated.Based on the theoretical study and experimental results,the feasibility of the aircraft’s large component docking attitude measurement method based on the draw-wire displacement sensor is verified.