Research On The Influence Of The Assembly Joint Interface On The Dynamic Characteristics Of The Seeker Servo Mechanism

The seeker servo is an actuator that achieves target tracking and visual axis stabilization.Its performance directly affects the guidance accuracy of the seeker.Assembly is the end link of the seeker servo mechanism manufacturing,which has a very important impact on the performance.The contact characteristics between the assembly joint interface of the seeker servo mechanism are determined by the assembly process parameters and its own structural properties during assembly.According to the different materials constituting the joint interface structure and the different pressures applied between the joint interface,the dynamic characteristics of the servo mechanism are greatly affected.Therefore,the joint interface of the seeker servo mechanism is used as a research starting point.Study the influence mechanism of assembly joint interface on the dynamic characteristics of seeker servo mechanism,and reveal the influence relationship between assembly process parameters of seeker servo mechanism and its dynamic characteristics.The main research contents of this paper are as follows:(1)Establishing stiffness model of assembly joint interface based on the contact theory.Persson contact theory and M-B fractal contact theory were used to model the stiffness of the joint interface.Persson contact theory was used to calculate the stiffness of the joint interface by calculating the compression deformation energy between the joint interface.The M-B fractal contact theory is a theoretical formula that deals with the contact of a single asperity combined with the Hertz contact theory.Calculate the overall contact stiffness of the joint surface when several asperities are in contact by integral sum.(2)Calculate the fractal parameters of real rough surface based on the roughness method.The fractal rough surface is constructed by the W-M function,which is known for the fractal dimension.The fractal dimension is obtained by different methods.By comparing the calculated fractal dimension values with known value,a method with smaller error is selected.This method is used to calculate the fractal dimension of the point cloud of the real rough surface obtained by the scanning microscope.This parameter is brought into the stiffness model of the assembly joint interface.(3)Establishing the equivalent model of joint interface based on Persson contact theory.Select the appropriate equivalent method of joint interface.The modeling software is used to construct the three-dimensional model of the three methods.Then the physical properties of the three-dimensional model are assigned according to the stiffness model of the joint interface.Finally,the modal analysis is carried out by using finite element software,and the modal experiment is carried out at the same time.Through the comparison of the modal shapes and frequencies obtained by modal simulation and modal experiment,the optimal equivalent method of joint interface is obtained,which is the virtual material method based on Persson contact theory.(4)Through the dynamic simulation and physical experiment verification,the influence of the assembly interface on the dynamic characteristics of the seeker servo mechanism is explored.Based on the theoretical method of the equivalent joint interface,each assembly joint surface can be equivalently characterized.The simulation model of the seeker servo mechanism is built,and the dynamics simulation of the servo mechanism is carried out,so as to study the influence of the assembly on the dynamic characteristics of the servo mechanism.The experimental prototype of the seeker servo mechanism is built.Finally,the resonance frequency experiment of the servo mechanism is performed to verify simulation data.In the end a large number of measured data and simulation data are used to fit the regression and excavate the knowledge of the assembly.