Research On Multi-function Target With Three Degrees Of Freedom And Interior Field Simulation

In the historical development of optical precision equipment,the detection technology for its performance plays a crucial role.The optical testing target is a special type of detection device used for indoor detection of the technical performance of photoelectric tracking measurement equipment.Currently,when detecting the technical performance of photoelectric tracking measurement equipment indoors,the main prevailing optical testing target generates a simulation target with limited motion trajectory,which is quite different from the motion characteristics of real maneuvering target,resulting in the detection result not being able to reasonably evaluate technical performance of the photoelectric tracking measurement equipment.Therefore,the development of a new generation of optical testing targets is of great significance to the development of optoelectronic tracking and measuring equipment.In this paper,the newly developed multi-functional testing target with three degrees of freedom and internal field simulation was taken as the research object,and the testing target was studied from different perspectives,including the analysis of the testing target from the system level,the improvement of the structural stiffness of the horizontal linear motion system of the testing target through structural strengthening,the kinematics and dynamics of the testing mechanism were studied,the spatial static pointing error of the testing target was theoretically modeled and error compensated,and the experimental platforms were built to conduct experimental research on the key components and overall performance of the testing target.The contents were described as follows:The design scheme and technical index requirements of multi-functional testing target with three degrees of freedom and internal field simulation were proposed according to the tracking performance detection requirements of a large-scale photoelectric tracking and measuring equipment.In the design scheme,the gantry support frame and the supporting beam were used as the base,the azimuth axis system,the horizontal linear motion system and the pitch axis system were used as the main moving components,and the collimator was used as the simulation target generator.Taking the base as the root,three moving components and collimator were sequentially connected by the joints to form a multi-body system mechanism.Driven by three motors,the testing target is capable of generating a simulated target that moves in azimuth and pitch directions..For the linear module driven by synchronous belt installed in the form of long-span cantilever beam,when it was used as the main component of horizontal linear motion system,the horizontal linear motion system had the problem of insufficient structural rigidity.The theory of straight beam bending vibration was studied to find out the main factors affecting the structural stiffness of long-span cantilever beam.The solution of structural strengthening in limited space was put forward,and the optimal shape and size of the reinforcement component were determined by the integrated optimization design.The simulation analysis and the vibration test of the linear motion system were carried out by the finite element method and the experimental method,respectively.These two results showed that the fundamental frequency of the overall structure was improved by 1.86 times after the reinforcement of the linear motion system,and the coincidence between the two was well,which showed that the design method of the reinforcement component was reasonable and reliable.The kinematics and dynamics of the multi-functional testing target with three degrees of freedom and in-field simulation were studied,and the electronic control system of the new mechanism was preliminarily designed.In Cartesian coordinate system,the kinematics equation of the mechanism was established by using the principle of homogeneous coordinate change,the velocity and acceleration of the simulated target were deduced,and the relationship between the velocity and acceleration of the simulated target and the three motion parameters of the mechanism was analyzed.The dynamic equation of the mechanism was established by using Lagrangian dynamics modeling method,and the relationship between the three driving forces and the three motion parameters were analyzed.The validity of the dynamic equation was verified by simulation software.Based on the kinematics and dynamics analysis,the electronic control system of the mechanism was preliminarily designed,and the three driving motors were selected reasonably.Spatial static pointing accuracy was the main design index of multi-functional detection target with three degrees of freedom and interior field simulation.In order to evaluate the pointing accuracy,the spatial static pointing error of the new mechanism was studied.Combining with the motion form of the new mechanism,the main error sources affecting the pointing error were found out,and the mathematical model of the spatial static pointing error was established according to the error modeling theory of multi-body system and the principle of homogeneous coordinate transformation.Based on the error model,the sensitivity of each error source to the pointing error and the distribution law of the pointing error were simulated and analyzed.An experimental platform was built to calibrate the spatial static pointing error in the workspace.In order to further improve the pointing accuracy,the coefficients in the error correction model were identified by the least square surface fitting method with calibrated data as fitting samples,and then the pointing error correction model was established.After correction,the pointing accuracy of the target had been improved obviously.Two experimental platforms were built.One was to test the linear motion error of slider by using linear displacement sensor.The results showed that the linear motion error of slider meets the design criteria.The other was to test the tracking performance of a photoelectric tracking and measuring device by using the traditional optical dynamic target and the newly developed detection target respectively.Through the comparison of the two detection results,the evaluation of multi-functional testing target with three degrees of freedom and internal field simulation was given.