Research On Laser Ranging Technology For Flying Targets

With the development of laser technology and photodetectors,laser ranging technology is widely used in space debris detection,satellite laser ranging,space rendezvous and docking,spacecraft autonomous landing,and target field photoelectric measurement.Due to its outstanding characteristics such as high range accuracy,range distance,flexible layout and good real-time data processing,laser ranging technology has gradually become an important measure for target measurement in the shooting range.Laser ranging technology has been relatively mature at domestic and overseas.However,there are still many problems to be solved in the application and system design of laser ranging for flying targets.(1)Causes and correction methods of laser ranging errors in flight targets;2)Influence of change of target shape and attitude on ranging accuracy(3)Factors affecting the stability of light return data and system optimization methods(4)Optimization of pulse laser ranging system for middle-distance flight targets.Therefore,this dissertation focuses on theoretical and experimental researches on the problems of laser ranging technology in the current single-station flight target trajectory measurement system,laying the foundation for further engineering development and application.The main research content is as follows:This thesis firstly analyzes the design method of each unit of ranging system from the perspective of system principle and composition,and analyzes the main parameters and performance of the ranging system.Theoretically,various error sources of laser range measurement for flying targets and their effects on ranging accuracy are studied.The error distribution of the main parameters of the flight target laser ranging system was calculated.It lays a theoretical foundation for system optimization design and error correction.Aiming at the influence of surface and posture changes of flying targets on the accuracy of range measurement,the pulse laser range echo process of flying targets was analyzed in depth.A theoretical model for calculating time domain distribution of the echo pulses by using the reflection characteristics,surface shape and attitude information of the flying targets was established.The concept of "differential projection cross-section distribution" for three-dimensional target pulsed laser ranging is proposed,which simplifies the convolution calculation of the time domain power distribution of the target echo,and solves the complexity of the target shape and variability of the attitude in the pulsed laser echoes,which is difficult to quantitatively analyze this problem in modeling.The law of pulse broadening and distance measurement errors which changed with the attitude angle has been found by the range echo simulation of a typical flight target.It provides a theoretical basis for the analysis and correction of the range error caused by echo distortion of the flying target.Aiming at the problem of poor stability of the light return data of the flying target laser ranging,a theoretical calculation model of the quasi-measurement probability of the laser target of the flying target was established.The effects of laser divergence angle,aiming accuracy,system receiving aperture,target scale and target distance alignment probability were analyzed.According to the analysis results,it was found that appropriately increasing the laser divergence angle in a reasonable range can suppress the impact of the aiming error alignment measurement probability,and The range of the best divergence angle for the ranging system with different aiming accuracy is given.Aiming at the system index parameters required by the laser ranging system,the flight target pulse laser ranging system scheme was designed.The detailed design and analysis were carried out from several aspects including the launch laser light source,launch and receive optical system,target detection optical system,multi-optical axis consistency calibration and detection circuit.Finally,the fixed-target distance-measuring echo characteristic experiment and the target tracking and ranging experiment of unmanned aerial vehicle target are designed.The experimental results show that the three-dimensional target pulse laser range echo calculation model and the target laser distance measurement are established.The effectiveness of the probability calculation model within a certain error range.Through the analysis of experimental distance measurement data of high-speed flight targets in the shooting range,combined with GPS ground calibration experiments,the performance of the ranging system was verified in terms of ranging capability,ranging accuracy and pre-test probability.