Research On Target Location Method Of Four-quadrant Laser Detector In Smoke And Dust Environmenton

Precision strikes has become the main form of local warfare and the massive application of guided munitions has directly changed the status and progress of the battlefield.The four-quadrant laser detector has become widely used in the field of intelligent ammunition due to its outstanding anti-electromagnetic interference ability and precise positioning ability.As the main passive jamming method of photoelectric detectors,smoke and dust causes reflection,refraction and absorption of laser signals,leading to laser energy attenuation,backscattering and spatial distribution changes,which seriously affect the hit accuracy of laser-guided munitions.To address these issues,this thesis explores the target positioning method of the four-quadrant laser detector in the smoke and dust environment.The main contribution is shown as follows:（1）The accurate mathematical model of spot position detection based on the Gaussian incident spot model is established according to the simulation and analysis of influence factors such as signal-to-noise ratio,spot center,spot beam waist radius and dark zone width.The interference characteristics of the soot particles on the output signal of the four-quadrant detector is explored to establish the backscatter model of the pulsed laser in the soot environment based on the soot particle laser radiation transmission theory,which provides a theoretical basis for the follow-up research.（2）Aiming at the problem of echo interference caused by the backscattering of soot and aerosol particles,the signal processing method of the four-quadrant detector in the soot environment is studied.After threshold processing and real-time wave gate gating,a target echo signal separation method based on wavelet analysis is developed.The wavelet threshold denoising method is used to eliminate the noise of the digitized laser echo signal firstly.Then it adopts the peak sharpening algorithm to improve the peak resolution of the echo signal and solve the problem of excessive peak overlap.Finally,obtain the peak position parameters by doing the continuous wavelet transformation on the sharpened echo signal,find the best Gaussian fitting waveform according to the peak position value and obtain the backscattered echo of soot aerosol particles and the target echo.（3）We analyse the typical spot position detection algorithm.Aiming at its current shortcomings such as low positioning accuracy,incomplete model and poor real-time performance,we use the circular spot with Gaussian distribution as the incident model and develop a spot location section algorithm called G-Infinite integral（GII）.Based on the traditional infinite integral fitting method,our algorithm takes into account the influence of the detector diameter and the width of the dark zone on the detection accuracy of the spot position.Besides,our algorithm applies the least square method to obtain the best-fitting solution expression which is used to expresses some solutions of the formula that perform piecewise polynomial fitting.In order to make the proposed algorithm more applicable in the smoke and dust environment,the smoke compensation coefficient is introduced to further correct the solution and get expression of the spot position of the GII algorithm in the smoke and dust environment.Finally,we have built an experimental platform for the laser detection system in the smoke and dust environment,analyze and process the output data of the laser detection system through MATLAB.It has been verified that when the mass concentration of smoke and dust is less than 7g/m~3,the four-quadrant detector target positioning method based on the GII algorithm in the smoke environment can achieve a detection accuracy of 10^-2mm in a larger detection range,which has improved by 58.3%compared with no processing algorithms.